//! Application session operations for prepared client changes and saved state.
//!
//! This module owns the boundary between a byte-preserving configuration draft,
//! encrypted vault data, backups, the recoverable saved-file adapter, and the
//! explicit runtime-restart confirmation boundary.

mod backups;
mod commit;
mod draft;
mod restore;

use draft::DraftChanges;

use std::collections::{BTreeMap, BTreeSet};
use std::ffi::OsStr;
use std::fmt;
use std::net::IpAddr;
use std::time::{Duration, Instant};

use thiserror::Error;
use time::OffsetDateTime;
use time::format_description::well_known::Rfc3339;

use crate::backup::{self, BackupError, BackupReason, HistoricalApplyStatus, SavedBytes};
use crate::delivery::files::{self, FileOutputError, PreparedDestination};
use crate::delivery::qr;
use crate::delivery::{self, ClientConfigPayload, DeliverySettings, QrCodeOutput, QrError};
use crate::domain::{
    AddressAvailability, ApplyStatus, Client, ClientAddresses, ClientStates, DomainError,
    PublicKey, Snapshot, allocate_ipv4, allocate_ipv6, validate_manual_ipv4, validate_manual_ipv6,
};
use crate::persistence::{BackupComplete, PersistedState, PersistenceError, SavedStore};
use crate::runtime::transport::TransportError;
use crate::runtime::{self, RuntimeObservation, SavedPeerProjection, TechnicalMatch};
use crate::service::{self, RestartDeadline, RestartExecution, RestartOutcome};
use crate::vault::source::{
    PreparedImportSetup, SelectedFileImportReport, SourceImportError, SourceImportReport,
};
use crate::vault::{VaultBundle, VaultError, WireGuardPrivateKey};
use crate::wireguard::SectionKind;
use crate::wireguard::{ConfigDocument, DocumentError, EditError};

/// Secret-free row for displaying every authoritative peer section.
/// `mutable_identity` is present only when the peer has an unambiguous,
/// supported projection into the client domain model.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct ClientDisplay {
    pub peer_index: usize,
    pub line: usize,
    pub identity: Option<PublicKey>,
    pub label: String,
    pub allowed_ips: Vec<String>,
    pub has_subnet_routes: bool,
    pub issues: Vec<crate::wireguard::PeerIssue>,
    pub mutable_identity: Option<PublicKey>,
}

impl ClientDisplay {
    /// Whether a retained parser issue describes a valid address shape the
    /// client model cannot manage, rather than a malformed configuration.
    pub fn is_capability_limitation_issue(&self, issue: &crate::wireguard::PeerIssue) -> bool {
        matches!(
            issue,
            crate::wireguard::PeerIssue::UnsupportedAllowedIpShape { .. }
                | crate::wireguard::PeerIssue::MissingIpv4HostRoute
        )
    }

    pub fn presented_issues(&self) -> impl Iterator<Item = &crate::wireguard::PeerIssue> {
        self.issues
            .iter()
            .filter(|issue| !self.is_capability_limitation_issue(issue))
    }
}

/// Secret-free display projection of the current document and client state.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SessionDisplay {
    pub clients: Vec<ClientDisplay>,
    pub document_issues: Vec<crate::wireguard::DocumentIssue>,
}

/// An open, in-memory management session. The configuration and state drafts
/// change independently of installed bytes until [`Self::commit`] succeeds.
pub struct Application {
    store: SavedStore,
    saved: SavedBytes,
    draft: DraftChanges,
    historical_apply: HistoricalApplyStatus,
    verified_saved_projection: Option<SavedPeerProjection>,
    active_restart_attempt: Option<u64>,
    next_restart_attempt: u64,
    next_issue_authorization: u64,
    initial_issues: BTreeMap<PublicKey, InitialIssue>,
}

#[allow(dead_code)] // M6.3 consumes the capability and its session-held key.
struct InitialIssue {
    private_key: WireGuardPrivateKey,
    context: IssueContext,
    stage: IssueStage,
}

#[derive(Clone, Copy, Eq, PartialEq)]
enum IssueStage {
    PendingDraft,
    AwaitingFirstFile,
    RetryAvailable,
    Authorizing(u64),
    RetryNeedsOverwriteConfirmation,
    RetryNeedsManualCleanup,
}

#[derive(Clone, Eq, PartialEq)]
struct IssueContext {
    peer_directives: String,
    encrypted_record: String,
}

/// Private, operation-local authorization for a single first-file publication.
/// Plaintext is never returned to a caller outside `deliver_first_issue`.
struct FirstIssueAuthorization {
    identity: PublicKey,
    context: IssueContext,
    token: u64,
    payload: ClientConfigPayload,
}

/// How a failed file operation affected publication. The caller must report
/// uncertainty honestly and request overwrite confirmation before retrying it.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
#[allow(dead_code)] // M6.3 constructs the delivery outcomes in production.
pub(crate) enum FirstIssueDeliveryFailure {
    BeforePublication,
    PublicationUncertain,
    CleanupRequired,
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum FirstIssueRetry {
    Available,
    OverwriteConfirmationRequired,
    /// Inspect and remove any retained private temporary file before retrying.
    ManualCleanupRequired,
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
/// Confirmation flags acknowledge the specific recovery action reported by the
/// preceding attempt; they do not authorize deleting any file automatically.
pub enum FirstIssueAttempt {
    Initial,
    Retry {
        confirm_possible_overwrite: bool,
        confirm_manual_cleanup: bool,
    },
}

/// Result of one bounded publication closure. The returned value can carry
/// operation-local material (for example a QR derived from the same payload).
#[allow(dead_code)] // M6.3 consumes the result of the publication boundary.
pub enum FirstIssueDeliveryOutcome<T, E> {
    Delivered(T),
    /// Publication completed, but the saved-state check that consumes the
    /// first-issue capability failed. The file exists; reissue now requires a
    /// fresh password authorization.
    PublishedButBookkeepingUncertain {
        value: T,
        error: AppError,
    },
    Failed {
        error: E,
        retry: FirstIssueRetry,
        /// The committed client is not verified as applied to the live
        /// interface. Keep this warning available even when publication is
        /// uncertain and the caller must ask before retrying.
        activation_warning: bool,
    },
}

/// Result of one mandatory file publication with an optional QR request.
/// The outer first-issue outcome reports file/bookkeeping status; this value
/// reports QR status independently so encoding failure cannot undo publication.
pub struct FirstIssueFileAndQr {
    pub activation_warning: bool,
    pub qr: Result<QrCodeOutput, QrError>,
}

/// Result metadata for a successful first-issue file publication.
pub struct FirstIssueFileDelivery {
    pub activation_warning: bool,
}

/// Stage at which a password-authorized reissue stopped.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum ReissueStage {
    SavedState,
    Authorization,
    Rendering,
    FilePublication,
}

/// Fixed, secret-free reissue failure categories.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum ReissueFailureKind {
    SavedStateUnavailable,
    VaultUnavailable,
    PasswordOrRecordRejected,
    ConfigurationRejected,
    FileOutput(FileOutputError),
}

/// A reissue failure identifies its stage without retaining password or payload data.
#[derive(Clone, Copy, Debug, Eq, PartialEq, Error)]
#[error("client reissue failed during {stage:?}: {kind:?}")]
pub struct ReissueError {
    pub stage: ReissueStage,
    pub kind: ReissueFailureKind,
}

/// Result of mandatory file delivery and optional QR encoding from the same bytes.
pub struct ReissueDelivery {
    pub activation_warning: bool,
    pub qr: Option<Result<QrCodeOutput, QrError>>,
}

impl fmt::Debug for ReissueDelivery {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        formatter
            .debug_struct("ReissueDelivery")
            .field("activation_warning", &self.activation_warning)
            .field("qr_requested", &self.qr.is_some())
            .field(
                "qr",
                &self
                    .qr
                    .as_ref()
                    .map(|result| result.as_ref().map(|_| "[REDACTED]")),
            )
            .finish()
    }
}

/// Read-only, saved-generation-bound restart preview for a future confirmation UI.
pub struct RestartPreview {
    saved: SavedBytes,
    interface: String,
    unit: String,
    timeout: Duration,
    projection: SavedPeerProjection,
    expected_clients: Option<Snapshot>,
    has_draft: bool,
}

impl RestartPreview {
    pub fn interface(&self) -> &str {
        &self.interface
    }

    pub fn systemd_unit(&self) -> &str {
        &self.unit
    }

    pub const fn has_draft(&self) -> bool {
        self.has_draft
    }
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum RestartChoice {
    Cancel,
    RestartSavedState,
    DiscardDraftAndRestart,
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum RestartStage {
    Cancelled,
    Preparation,
    Backup,
    Service,
    RuntimeRead,
    Verification,
    Persistence,
    Complete,
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum RestartFailureKind {
    InvalidOrStaleSavedGeneration,
    UnsafeSaveConfig,
    UnsupportedSavedShape,
    BackupFailed,
    DraftDiscardFailed,
    ServiceFailed,
    RuntimeReadFailed,
    RuntimeNoDevice,
    RuntimePermissionDenied,
    RuntimeMalformed,
    RuntimeTransport,
    RuntimeTimeout,
    RuntimeLimitExceeded,
    RuntimeMismatch,
    VerificationPersistenceFailed,
}

/// Secret-free explanation for saved configuration that cannot be used as a
/// restart verification target. The identity is a public WireGuard key.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct RestartDiagnostic {
    pub identity: Option<PublicKey>,
    pub section_line: Option<usize>,
    pub reason: &'static str,
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct RestartReport {
    pub stage: RestartStage,
    pub failure: Option<RestartFailureKind>,
    pub service_failure: Option<service::RestartFailure>,
    pub service_phase: Option<service::RestartPhase>,
    pub systemd_unit: Option<String>,
    pub backup_path: Option<std::path::PathBuf>,
    pub restart_submitted: bool,
    pub restart_may_still_complete: bool,
    pub manual_recovery_required: bool,
}

struct RestartAttempt {
    id: u64,
    saved: SavedBytes,
}

/// Read-only restore details and an opaque, byte-bound confirmation value.
/// The value contains the validated archive payload; confirmation never rereads
/// a path whose contents may have changed since preview.
pub struct RestorePreview {
    created_at_utc: String,
    reason: BackupReason,
    historical_apply: HistoricalApplyStatus,
    installed_generation: SavedBytes,
    saved_bytes: SavedBytes,
}

impl RestorePreview {
    pub fn created_at_utc(&self) -> &str {
        &self.created_at_utc
    }

    pub const fn reason(&self) -> BackupReason {
        self.reason
    }

    pub fn historical_apply(&self) -> &HistoricalApplyStatus {
        &self.historical_apply
    }

    /// Safe comparison against current saved bytes for a restore confirmation screen.
    pub fn change_summary(&self, current: &SavedBytes) -> RestoreChangeSummary {
        let peer_map = |bytes: &[u8]| {
            ConfigDocument::parse(bytes)
                .map(|document| {
                    document
                        .peers()
                        .iter()
                        .filter_map(|peer| {
                            peer.identity.map(|key| {
                                (
                                    key,
                                    peer.allowed_ips
                                        .iter()
                                        .map(ToString::to_string)
                                        .collect::<Vec<_>>(),
                                )
                            })
                        })
                        .collect::<BTreeMap<_, _>>()
                })
                .unwrap_or_default()
        };
        let current_peer_map = peer_map(&current.server_config);
        let proposed_peer_map = peer_map(&self.saved_bytes.server_config);
        let current_peers = current_peer_map.keys().copied().collect::<BTreeSet<_>>();
        let proposed_peers = proposed_peer_map.keys().copied().collect::<BTreeSet<_>>();
        let changed_clients = current_peers
            .intersection(&proposed_peers)
            .filter(|key| current_peer_map.get(key) != proposed_peer_map.get(key))
            .copied()
            .collect();
        RestoreChangeSummary {
            settings_changed: current.settings != self.saved_bytes.settings,
            settings_fields_changed: settings_fields_changed(
                &current.settings,
                &self.saved_bytes.settings,
            ),
            added_clients: proposed_peers.difference(&current_peers).copied().collect(),
            removed_clients: current_peers.difference(&proposed_peers).copied().collect(),
            changed_clients,
            server_config_changed: current.server_config != self.saved_bytes.server_config,
            vault_changed: current.vault != self.saved_bytes.vault,
        }
    }
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct RestoreChangeSummary {
    pub settings_changed: bool,
    pub settings_fields_changed: Vec<&'static str>,
    pub server_config_changed: bool,
    pub vault_changed: bool,
    pub added_clients: Vec<PublicKey>,
    pub removed_clients: Vec<PublicKey>,
    pub changed_clients: Vec<PublicKey>,
}

fn settings_fields_changed(current: &[u8], proposed: &[u8]) -> Vec<&'static str> {
    let parse = |bytes: &[u8]| {
        std::str::from_utf8(bytes)
            .ok()
            .and_then(|text| crate::config::SettingsFile::parse_toml(text).ok())
    };
    let (Some(current), Some(proposed)) = (parse(current), parse(proposed)) else {
        return vec!["settings file"];
    };
    let mut fields = Vec::new();
    if current.interface_name != proposed.interface_name {
        fields.push("interface name");
    }
    if current.server_config_path != proposed.server_config_path {
        fields.push("server configuration path");
    }
    if current.client_source_directory != proposed.client_source_directory {
        fields.push("client source directory");
    }
    if current.server_endpoint != proposed.server_endpoint {
        fields.push("server endpoint");
    }
    if current.ipv4_allocation_range != proposed.ipv4_allocation_range {
        fields.push("IPv4 allocation range");
    }
    if current.ipv6_allocation_range != proposed.ipv6_allocation_range {
        fields.push("IPv6 allocation range");
    }
    if current.dns_addresses != proposed.dns_addresses {
        fields.push("DNS addresses");
    }
    if current.systemd_unit != proposed.systemd_unit {
        fields.push("systemd unit");
    }
    if current.restart_timeout_seconds != proposed.restart_timeout_seconds {
        fields.push("restart timeout");
    }
    if current.data_root != proposed.data_root {
        fields.push("data directory");
    }
    fields
}

impl fmt::Debug for RestorePreview {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        formatter
            .debug_struct("RestorePreview")
            .field("created_at_utc", &self.created_at_utc)
            .field("reason", &self.reason)
            .field("historical_apply", &self.historical_apply)
            .field("saved_bytes", &self.saved_bytes)
            .finish()
    }
}

impl fmt::Debug for Application {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        formatter
            .debug_struct("Application")
            .field("saved", &self.saved)
            .field("document", &self.draft.document)
            .field("states", &self.draft.states)
            .field("vault_present", &self.draft.vault.is_some())
            .field("historical_apply", &self.historical_apply)
            .field(
                "restart_attempt_active",
                &self.active_restart_attempt.is_some(),
            )
            .field(
                "pending_reservation_count",
                &self
                    .draft
                    .states
                    .address_reservations()
                    .pending_host_routes()
                    .count(),
            )
            .field("initial_issue_count", &self.initial_issues.len())
            .finish()
    }
}

impl Application {
    /// Open validated installed bytes and apply conservative persisted address
    /// reservations to the caller's narrower client-state model.
    pub fn open(store: SavedStore, states: ClientStates) -> Result<Self, AppError> {
        let saved = store.read_saved()?;
        Self::open_saved(store, saved, states)
    }

    /// Open a session by deriving its supported state from the authoritative
    /// saved server document. Unsupported peers remain available through
    /// [`Self::display_projection`] but never gain a guessed mutation identity.
    pub fn open_from_saved_store(store: SavedStore) -> Result<Self, AppError> {
        let saved = store.read_saved()?;
        let document = ConfigDocument::parse(&saved.server_config)?;
        let states = ClientStates::new(
            snapshot_from_document(&document),
            None,
            ApplyStatus::Unknown,
        )?;
        Self::open_saved(store, saved, states)
    }

    fn open_saved(
        store: SavedStore,
        saved: SavedBytes,
        mut states: ClientStates,
    ) -> Result<Self, AppError> {
        states.begin_runtime_session();
        let document = ConfigDocument::parse(&saved.server_config)?;
        let vault = saved
            .vault
            .as_deref()
            .map(std::str::from_utf8)
            .transpose()
            .map_err(|_| AppError::InvalidSavedState)?
            .map(VaultBundle::from_toml)
            .transpose()?;
        if let Some(bytes) = &saved.internal_state {
            PersistedState::from_toml(bytes)?.apply_to(&mut states)?;
        }
        let historical_apply = historical_apply_from_saved(&saved)?;
        Ok(Self {
            store,
            saved,
            draft: DraftChanges::new(document, states, vault),
            historical_apply,
            verified_saved_projection: None,
            active_restart_attempt: None,
            next_restart_attempt: 1,
            next_issue_authorization: 1,
            initial_issues: BTreeMap::new(),
        })
    }

    pub fn saved_bytes(&self) -> &SavedBytes {
        &self.saved
    }

    pub fn document(&self) -> &ConfigDocument {
        &self.draft.document
    }

    pub fn states(&self) -> &ClientStates {
        &self.draft.states
    }

    /// Return a secret-free projection that includes unsupported and
    /// ambiguous peers instead of silently omitting them from the client list.
    pub fn display_projection(&self) -> SessionDisplay {
        let clients = self
            .draft
            .document
            .peers()
            .iter()
            .map(|peer| {
                let projected = peer
                    .identity
                    .and_then(|identity| self.draft.document.project_client(&identity).ok());
                let metadata_label = match &peer.metadata {
                    crate::wireguard::MetadataAttachment::Valid { metadata, .. } => {
                        Some(metadata.alias.clone())
                    }
                    _ => None,
                };
                let identity = peer.identity;
                let label = metadata_label.unwrap_or_else(|| {
                    identity.map_or_else(
                        || format!("Peer at line {}", peer.section_line),
                        |key| format!("{}…", key.to_string().chars().take(8).collect::<String>()),
                    )
                });
                ClientDisplay {
                    peer_index: peer.index,
                    line: peer.section_line,
                    identity,
                    label,
                    allowed_ips: peer.allowed_ips.iter().map(ToString::to_string).collect(),
                    has_subnet_routes: peer.has_subnet_routes,
                    issues: peer.issues.clone(),
                    mutable_identity: projected
                        .filter(|client| self.draft.states.draft().get(&client.identity).is_some())
                        .map(|client| client.identity),
                }
            })
            .collect();
        SessionDisplay {
            clients,
            document_issues: self.draft.document.issues().to_vec(),
        }
    }

    /// Add one prepared public-key client to the byte-preserving server draft
    /// and the narrower in-memory client draft.
    pub fn add_client(
        &mut self,
        client: Client,
        created_utc: Option<&str>,
    ) -> Result<(), AppError> {
        let edited = ConfigDocument::parse(
            self.draft
                .document
                .add_client(&client, created_utc)?
                .render(),
        )?;
        ensure_document_client(&edited, &client)?;
        let mut next_states = self.draft.states.clone();
        next_states.stage_client(client)?;
        let replacement = DraftChanges::stage_clients(edited, next_states);
        self.draft.publish_replacement(replacement);
        self.invalidate_active_issue_authorizations();
        Ok(())
    }

    /// Prepare a new dual-stack client and its encrypted key as one in-memory
    /// operation. `manual_addresses == None` selects the lowest available host
    /// in each configured range. No file is written and no output is authorized
    /// until a later successful Commit.
    pub fn prepare_new_client(
        &mut self,
        alias: &str,
        manual_addresses: Option<ClientAddresses>,
        created_utc: Option<&str>,
    ) -> Result<PublicKey, AppError> {
        let installed = self.store.read_saved()?;
        let settings = self.store.resolved_settings_for(&installed)?;
        let key = WireGuardPrivateKey::generate().map_err(|_| AppError::KeyGenerationFailed)?;
        let identity = key.public_key();

        let server_addresses = server_interface_addresses(&self.draft.document)?;
        let mut occupied = self
            .draft
            .states
            .addresses_in_use()
            .into_iter()
            .collect::<Vec<_>>();
        occupied.extend(document_host_addresses(&self.draft.document));
        let reserved = self
            .draft
            .states
            .address_reservations()
            .all()
            .collect::<Vec<_>>();
        let availability = AddressAvailability {
            server: &server_addresses,
            occupied: &occupied,
            reserved: &reserved,
        };
        let addresses = match manual_addresses {
            Some(addresses) => {
                let ipv6 = addresses.ipv6.ok_or(AppError::NewClientMustBeDualStack)?;
                validate_manual_ipv4(
                    addresses.ipv4,
                    settings.ipv4_allocation_range,
                    &availability,
                )?;
                validate_manual_ipv6(ipv6, settings.ipv6_allocation_range, &availability)?;
                ClientAddresses {
                    ipv4: addresses.ipv4,
                    ipv6: Some(ipv6),
                }
            }
            None => ClientAddresses {
                ipv4: allocate_ipv4(settings.ipv4_allocation_range, &availability)?,
                ipv6: Some(allocate_ipv6(
                    settings.ipv6_allocation_range,
                    &availability,
                )?),
            },
        };
        let client = Client::new(identity, alias, addresses)?;

        // Prepare every fallible replacement off to the side. The live app is
        // mutated only after document editing, state insertion, and encryption
        // have all succeeded.
        let next_document = self.draft.document.add_client(&client, created_utc)?;
        let mut next_states = self.draft.states.clone();
        next_states.stage_client(client.clone())?;
        let existing_vault = self
            .draft
            .vault
            .as_ref()
            .ok_or(AppError::VaultMissingForCreation)?;
        let encoded = existing_vault.to_toml()?;
        let mut next_vault = VaultBundle::from_toml(&encoded)?;
        next_vault.encrypt_record(identity, &key)?;
        // Parse once before publication so a malformed editor result cannot
        // leave the three in-memory drafts out of sync.
        let next_document = ConfigDocument::parse(next_document.render())?;
        ensure_document_client(&next_document, &client)?;
        next_vault.to_toml()?;
        let context = issue_context(&next_document, &next_vault, identity)?;
        let replacement =
            DraftChanges::stage_clients_and_vault(next_document, next_states, Some(next_vault));
        self.invalidate_active_issue_authorizations();
        self.draft.publish_replacement(replacement);
        self.initial_issues.insert(
            identity,
            InitialIssue {
                private_key: key,
                context,
                stage: IssueStage::PendingDraft,
            },
        );
        Ok(identity)
    }

    /// Publish a password-free first issue while the committed peer, encrypted
    /// record, and one-use token are valid. The mutable app borrow remains held
    /// across `publish`, so no application mutation can interleave after the
    /// final saved-state validation and before the file adapter runs.
    #[allow(dead_code)] // M6.3 invokes this for its initial-file action.
    pub(crate) fn deliver_first_issue<T, E>(
        &mut self,
        identity: PublicKey,
        attempt: FirstIssueAttempt,
        publish: impl FnOnce(&ClientConfigPayload) -> Result<T, (E, FirstIssueDeliveryFailure)>,
    ) -> Result<FirstIssueDeliveryOutcome<T, E>, AppError> {
        self.deliver_first_issue_with_warning(identity, attempt, |payload, _| publish(payload))
    }

    fn deliver_first_issue_with_warning<T, E>(
        &mut self,
        identity: PublicKey,
        attempt: FirstIssueAttempt,
        publish: impl FnOnce(&ClientConfigPayload, bool) -> Result<T, (E, FirstIssueDeliveryFailure)>,
    ) -> Result<FirstIssueDeliveryOutcome<T, E>, AppError> {
        let (is_retry, confirm_possible_overwrite, confirm_manual_cleanup) = match attempt {
            FirstIssueAttempt::Initial => (false, false, false),
            FirstIssueAttempt::Retry {
                confirm_possible_overwrite,
                confirm_manual_cleanup,
            } => (true, confirm_possible_overwrite, confirm_manual_cleanup),
        };
        let authorization = self.authorize_first_issue_inner(
            identity,
            is_retry,
            confirm_possible_overwrite,
            confirm_manual_cleanup,
        )?;
        let activation_warning = match self.validate_first_issue_authorization(&authorization) {
            Ok(warning) => warning,
            Err(error) => {
                self.require_overwrite_confirmation(identity);
                return Err(error);
            }
        };
        match publish(&authorization.payload, activation_warning) {
            Ok(value) => {
                if let Err(error) = self.mark_first_issue_delivered(authorization) {
                    // Publication is definite. Drop the session-held key even
                    // when saved-state bookkeeping cannot be completed.
                    self.initial_issues.remove(&identity);
                    return Ok(
                        FirstIssueDeliveryOutcome::PublishedButBookkeepingUncertain {
                            value,
                            error,
                        },
                    );
                }
                Ok(FirstIssueDeliveryOutcome::Delivered(value))
            }
            Err((error, failure)) => {
                let retry = match self.mark_first_issue_delivery_failed(authorization, failure) {
                    Ok(retry) => retry,
                    Err(error) => {
                        self.require_overwrite_confirmation(identity);
                        return Err(error);
                    }
                };
                Ok(FirstIssueDeliveryOutcome::Failed {
                    error,
                    retry,
                    activation_warning,
                })
            }
        }
    }

    /// Prepare a caller-selected plaintext destination without writing it. The
    /// returned destination records any existing regular file so a later
    /// overwrite confirmation is bound to this exact selection.
    pub fn prepare_first_issue_destination(
        &self,
        path: impl AsRef<std::path::Path>,
    ) -> Result<PreparedDestination, FileOutputError> {
        let protection = self.store.delivery_output_protection()?;
        files::prepare_destination(path, &protection)
    }

    /// Deliver the committed new-client configuration through the app-owned
    /// one-use authorization closure. A failed write retains retry eligibility;
    /// a post-publication sync failure requires an explicit overwrite retry.
    pub fn deliver_first_issue_file(
        &mut self,
        identity: PublicKey,
        attempt: FirstIssueAttempt,
        destination: PreparedDestination,
    ) -> Result<FirstIssueDeliveryOutcome<FirstIssueFileDelivery, FileOutputError>, AppError> {
        self.deliver_first_issue_file_with(identity, attempt, destination, files::publish)
    }

    fn deliver_first_issue_file_with(
        &mut self,
        identity: PublicKey,
        attempt: FirstIssueAttempt,
        destination: PreparedDestination,
        publish_file: impl FnOnce(
            PreparedDestination,
            &ClientConfigPayload,
        ) -> Result<(), FileOutputError>,
    ) -> Result<FirstIssueDeliveryOutcome<FirstIssueFileDelivery, FileOutputError>, AppError> {
        self.deliver_first_issue_with_warning(identity, attempt, |payload, activation_warning| {
            publish_file(destination, payload).map_err(|error| {
                let failure = match error {
                    FileOutputError::PublicationUncertain => {
                        FirstIssueDeliveryFailure::PublicationUncertain
                    }
                    FileOutputError::ManualCleanupRequired => {
                        FirstIssueDeliveryFailure::CleanupRequired
                    }
                    _ => FirstIssueDeliveryFailure::BeforePublication,
                };
                (error, failure)
            })?;
            Ok(FirstIssueFileDelivery { activation_warning })
        })
    }

    /// Publish the mandatory plaintext file, then optionally encode a QR from
    /// that same authorized payload. QR failure is returned separately and the
    /// successful file publication still consumes first-issue eligibility.
    pub fn deliver_first_issue_file_and_qr(
        &mut self,
        identity: PublicKey,
        attempt: FirstIssueAttempt,
        destination: PreparedDestination,
    ) -> Result<FirstIssueDeliveryOutcome<FirstIssueFileAndQr, FileOutputError>, AppError> {
        self.deliver_first_issue_file_and_qr_with(identity, attempt, destination, |payload| {
            qr::encode_payload(payload)
        })
    }

    fn deliver_first_issue_file_and_qr_with(
        &mut self,
        identity: PublicKey,
        attempt: FirstIssueAttempt,
        destination: PreparedDestination,
        encode: impl FnOnce(&ClientConfigPayload) -> Result<QrCodeOutput, QrError>,
    ) -> Result<FirstIssueDeliveryOutcome<FirstIssueFileAndQr, FileOutputError>, AppError> {
        self.deliver_first_issue_file_and_qr_with_publisher(
            identity,
            attempt,
            destination,
            files::publish,
            encode,
        )
    }

    fn deliver_first_issue_file_and_qr_with_publisher(
        &mut self,
        identity: PublicKey,
        attempt: FirstIssueAttempt,
        destination: PreparedDestination,
        publish_file: impl FnOnce(
            PreparedDestination,
            &ClientConfigPayload,
        ) -> Result<(), FileOutputError>,
        encode: impl FnOnce(&ClientConfigPayload) -> Result<QrCodeOutput, QrError>,
    ) -> Result<FirstIssueDeliveryOutcome<FirstIssueFileAndQr, FileOutputError>, AppError> {
        self.deliver_first_issue_with_warning(identity, attempt, |payload, activation_warning| {
            publish_file(destination, payload).map_err(|error| {
                let failure = match error {
                    FileOutputError::PublicationUncertain => {
                        FirstIssueDeliveryFailure::PublicationUncertain
                    }
                    FileOutputError::ManualCleanupRequired => {
                        FirstIssueDeliveryFailure::CleanupRequired
                    }
                    _ => FirstIssueDeliveryFailure::BeforePublication,
                };
                (error, failure)
            })?;
            Ok(FirstIssueFileAndQr {
                activation_warning,
                qr: encode(payload),
            })
        })
    }

    /// Reissue a saved client's configuration after freshly unlocking its
    /// installed vault record with this action's password. This operation reads
    /// only installed saved bytes, never uses a draft or retained source file,
    /// and publishes the required file before attempting optional QR encoding.
    pub fn reissue_client_file(
        &self,
        identity: PublicKey,
        password: &str,
        destination: PreparedDestination,
        include_qr: bool,
    ) -> Result<ReissueDelivery, ReissueError> {
        let installed = self.store.read_saved().map_err(|_| ReissueError {
            stage: ReissueStage::SavedState,
            kind: ReissueFailureKind::SavedStateUnavailable,
        })?;
        let document =
            ConfigDocument::parse(&installed.server_config).map_err(|_| ReissueError {
                stage: ReissueStage::SavedState,
                kind: ReissueFailureKind::SavedStateUnavailable,
            })?;
        let encoded_vault = installed.vault.as_deref().ok_or(ReissueError {
            stage: ReissueStage::Authorization,
            kind: ReissueFailureKind::VaultUnavailable,
        })?;
        let vault_text = std::str::from_utf8(encoded_vault).map_err(|_| ReissueError {
            stage: ReissueStage::Authorization,
            kind: ReissueFailureKind::VaultUnavailable,
        })?;
        let vault = VaultBundle::from_toml(vault_text).map_err(|_| ReissueError {
            stage: ReissueStage::Authorization,
            kind: ReissueFailureKind::VaultUnavailable,
        })?;
        // Retrieval performs the password unlock and authenticated conflict
        // check on every invocation. The short-lived owner is dropped when
        // this method returns and is never kept in Application state.
        let record = vault
            .retrieve_client_record(identity, password)
            .map_err(|_| ReissueError {
                stage: ReissueStage::Authorization,
                kind: ReissueFailureKind::PasswordOrRecordRejected,
            })?;
        let resolved = self
            .store
            .resolved_settings_for(&installed)
            .map_err(|_| ReissueError {
                stage: ReissueStage::SavedState,
                kind: ReissueFailureKind::SavedStateUnavailable,
            })?;
        let delivery_settings = DeliverySettings {
            server_endpoint: &resolved.server_endpoint,
            dns_addresses: &resolved.dns_addresses,
        };
        let payload = if record.is_new_template() {
            delivery::render_new_client(
                identity,
                record.private_key().ok_or(ReissueError {
                    stage: ReissueStage::Authorization,
                    kind: ReissueFailureKind::PasswordOrRecordRejected,
                })?,
                &document,
                &delivery_settings,
            )
        } else {
            delivery::render_imported_client(identity, &record, &document, &delivery_settings)
        }
        .map_err(|_| ReissueError {
            stage: ReissueStage::Rendering,
            kind: ReissueFailureKind::ConfigurationRejected,
        })?;

        files::publish(destination, &payload).map_err(|error| ReissueError {
            stage: ReissueStage::FilePublication,
            kind: ReissueFailureKind::FileOutput(error),
        })?;

        // A historical timestamp is deliberately insufficient: after reopen,
        // the runtime observation is unknown. Warn unless this live session
        // has verified the exact saved peer snapshot currently on disk.
        let activation_warning = !self.saved_generation_is_verified_applied(&installed, &document);
        let qr = include_qr.then(|| qr::encode_payload(&payload));
        Ok(ReissueDelivery {
            activation_warning,
            qr,
        })
    }

    fn saved_generation_is_verified_applied(
        &self,
        installed: &SavedBytes,
        document: &ConfigDocument,
    ) -> bool {
        if !same_saved_bytes(&self.saved, installed) || self.verified_saved_projection.is_none() {
            return false;
        }
        let Ok((projection, _)) = restart_projection_from_document(document) else {
            return false;
        };
        self.draft.states.applied() == &ApplyStatus::Verified
            && self.verified_saved_projection.as_ref() == Some(&projection)
    }

    /// Recheck both the one-use token and installed saved generation as the
    /// final step before handing plaintext to the bounded writer closure.
    fn validate_first_issue_authorization(
        &mut self,
        authorization: &FirstIssueAuthorization,
    ) -> Result<bool, AppError> {
        let installed = match self.store.read_saved() {
            Ok(saved) => saved,
            Err(error) => {
                self.initial_issues.clear();
                return Err(error.into());
            }
        };
        let document = ConfigDocument::parse(&installed.server_config)?;
        let vault = installed
            .vault
            .as_deref()
            .map(std::str::from_utf8)
            .transpose()
            .map_err(|_| AppError::InvalidSavedState)?
            .map(VaultBundle::from_toml)
            .transpose()?;
        self.retain_matching_issues(&document, vault.as_ref());
        let current = issue_context(
            &document,
            vault.as_ref().ok_or(AppError::FirstIssueUnavailable)?,
            authorization.identity,
        )?;
        if current != authorization.context
            || !matches!(
                self.initial_issues.get(&authorization.identity),
                Some(issue)
                    if issue.stage == IssueStage::Authorizing(authorization.token)
                        && issue.context == authorization.context
            )
        {
            return Err(AppError::FirstIssueUnavailable);
        }
        Ok(!self.saved_generation_is_verified_applied(&installed, &document))
    }

    fn require_overwrite_confirmation(&mut self, identity: PublicKey) {
        if let Some(issue) = self.initial_issues.get_mut(&identity)
            && matches!(issue.stage, IssueStage::Authorizing(_))
        {
            issue.stage = IssueStage::RetryNeedsOverwriteConfirmation;
        }
    }

    fn authorize_first_issue_inner(
        &mut self,
        identity: PublicKey,
        is_retry: bool,
        confirm_possible_overwrite: bool,
        confirm_manual_cleanup: bool,
    ) -> Result<FirstIssueAuthorization, AppError> {
        let installed = match self.store.read_saved() {
            Ok(saved) => saved,
            Err(error) => {
                self.initial_issues.clear();
                return Err(error.into());
            }
        };
        let document = ConfigDocument::parse(&installed.server_config)?;
        let vault = installed
            .vault
            .as_deref()
            .map(std::str::from_utf8)
            .transpose()
            .map_err(|_| AppError::InvalidSavedState)?
            .map(VaultBundle::from_toml)
            .transpose()?;
        self.retain_matching_issues(&document, vault.as_ref());
        let Some(issue) = self.initial_issues.get(&identity) else {
            return Err(AppError::FirstIssueUnavailable);
        };
        let allowed = match issue.stage {
            IssueStage::AwaitingFirstFile => !is_retry,
            IssueStage::RetryAvailable => is_retry,
            IssueStage::RetryNeedsOverwriteConfirmation => is_retry && confirm_possible_overwrite,
            IssueStage::RetryNeedsManualCleanup => is_retry && confirm_manual_cleanup,
            IssueStage::PendingDraft | IssueStage::Authorizing(_) => false,
        };
        if !allowed {
            return Err(AppError::FirstIssueUnavailable);
        }
        let private_key = &issue.private_key;
        let context = issue.context.clone();
        let current_context = issue_context(
            &document,
            vault.as_ref().ok_or(AppError::FirstIssueUnavailable)?,
            identity,
        )?;
        if current_context != context {
            self.initial_issues.remove(&identity);
            return Err(AppError::FirstIssueUnavailable);
        }
        let resolved = self.store.resolved_settings_for(&installed)?;
        let delivery_settings = DeliverySettings {
            server_endpoint: &resolved.server_endpoint,
            dns_addresses: &resolved.dns_addresses,
        };
        let payload =
            delivery::render_new_client(identity, private_key, &document, &delivery_settings)?;
        let token = self.next_issue_authorization;
        let next_token = token
            .checked_add(1)
            .ok_or(AppError::IssueAuthorizationExhausted)?;
        self.next_issue_authorization = next_token;
        let issue = self
            .initial_issues
            .get_mut(&identity)
            .ok_or(AppError::FirstIssueUnavailable)?;
        issue.stage = IssueStage::Authorizing(token);
        Ok(FirstIssueAuthorization {
            identity,
            context,
            token,
            payload,
        })
    }

    /// Consume first-issue eligibility after complete file publication.
    fn mark_first_issue_delivered(
        &mut self,
        authorization: FirstIssueAuthorization,
    ) -> Result<(), AppError> {
        let installed = match self.store.read_saved() {
            Ok(saved) => saved,
            Err(error) => {
                self.initial_issues.clear();
                return Err(error.into());
            }
        };
        let document = ConfigDocument::parse(&installed.server_config)?;
        let vault = installed
            .vault
            .as_deref()
            .map(std::str::from_utf8)
            .transpose()
            .map_err(|_| AppError::InvalidSavedState)?
            .map(VaultBundle::from_toml)
            .transpose()?;
        self.retain_matching_issues(&document, vault.as_ref());
        let current = issue_context(
            &document,
            vault.as_ref().ok_or(AppError::FirstIssueUnavailable)?,
            authorization.identity,
        )?;
        let matches_authorization = matches!(
            self.initial_issues.get(&authorization.identity),
            Some(issue)
                if issue.stage == IssueStage::Authorizing(authorization.token)
                    && issue.context == authorization.context
                    && issue.context == current
        );
        if !matches_authorization {
            return Err(AppError::FirstIssueUnavailable);
        }
        self.initial_issues.remove(&authorization.identity);
        Ok(())
    }

    /// Record failed publication and explicitly return the session to a retry
    /// state. Uncertain publication requires confirmed overwrite on the retry.
    fn mark_first_issue_delivery_failed(
        &mut self,
        authorization: FirstIssueAuthorization,
        failure: FirstIssueDeliveryFailure,
    ) -> Result<FirstIssueRetry, AppError> {
        let installed = match self.store.read_saved() {
            Ok(saved) => saved,
            Err(error) => {
                self.initial_issues.clear();
                return Err(error.into());
            }
        };
        let document = ConfigDocument::parse(&installed.server_config)?;
        let vault = installed
            .vault
            .as_deref()
            .map(std::str::from_utf8)
            .transpose()
            .map_err(|_| AppError::InvalidSavedState)?
            .map(VaultBundle::from_toml)
            .transpose()?;
        self.retain_matching_issues(&document, vault.as_ref());
        let current = issue_context(
            &document,
            vault.as_ref().ok_or(AppError::FirstIssueUnavailable)?,
            authorization.identity,
        )?;
        let Some(issue) = self.initial_issues.get_mut(&authorization.identity) else {
            return Err(AppError::FirstIssueUnavailable);
        };
        if issue.stage != IssueStage::Authorizing(authorization.token)
            || issue.context != authorization.context
            || issue.context != current
        {
            return Err(AppError::FirstIssueUnavailable);
        }
        let retry = match failure {
            FirstIssueDeliveryFailure::BeforePublication => {
                issue.stage = IssueStage::RetryAvailable;
                FirstIssueRetry::Available
            }
            FirstIssueDeliveryFailure::PublicationUncertain => {
                issue.stage = IssueStage::RetryNeedsOverwriteConfirmation;
                FirstIssueRetry::OverwriteConfirmationRequired
            }
            FirstIssueDeliveryFailure::CleanupRequired => {
                issue.stage = IssueStage::RetryNeedsManualCleanup;
                FirstIssueRetry::ManualCleanupRequired
            }
        };
        Ok(retry)
    }

    #[allow(dead_code)] // Used by the gated M6.3 capability methods.
    fn retain_matching_issues(&mut self, document: &ConfigDocument, vault: Option<&VaultBundle>) {
        retain_matching_issue_map(&mut self.initial_issues, document, vault);
    }

    fn invalidate_active_issue_authorizations(&mut self) {
        for issue in self.initial_issues.values_mut() {
            if matches!(issue.stage, IssueStage::Authorizing(_)) {
                issue.stage = IssueStage::RetryNeedsOverwriteConfirmation;
            }
        }
    }

    pub fn vault(&self) -> Option<&VaultBundle> {
        self.draft.vault.as_ref()
    }

    /// Whether a vault is present in either saved state or the current draft.
    /// This reveals only setup availability, never vault contents.
    pub fn vault_initialized(&self) -> bool {
        self.draft.vault.is_some()
    }

    /// Whether the in-memory client/document/vault draft differs from saved.
    pub fn has_draft_changes(&self) -> bool {
        self.has_draft()
    }

    /// Import one explicitly selected configured-directory entry into the
    /// in-memory vault draft. The result contains only redacted reconciliation
    /// data; saved files are changed only by a later Commit.
    pub fn import_selected_file(
        &mut self,
        selected_name: &OsStr,
    ) -> Result<SelectedFileImportReport, AppError> {
        let settings = self.store.resolved_settings_for(&self.saved)?;
        let existing_vault = self
            .draft
            .vault
            .as_ref()
            .ok_or(AppError::VaultMissingForCreation)?;
        let encoded = existing_vault.to_toml()?;
        let mut next_vault = VaultBundle::from_toml(&encoded)?;
        let report = crate::vault::source::import_selected_file(
            &mut next_vault,
            &settings,
            &self.draft.document,
            selected_name,
        )
        .map_err(AppError::SourceImport)?;
        next_vault.to_toml()?;
        let replacement = DraftChanges::stage_vault(Some(next_vault));
        self.draft.publish_replacement(replacement);
        Ok(report)
    }

    /// Replace a client's alias through the span-preserving config editor.
    /// A peer outside the narrower M1 state projection remains editable.
    pub fn rename_client(&mut self, identity: PublicKey, alias: &str) -> Result<(), AppError> {
        let edited = ConfigDocument::parse(
            self.draft
                .document
                .rename_client(&identity, alias)?
                .render(),
        )?;
        let mut next_states = self.draft.states.clone();
        if let Some(client) = next_states.draft().get(&identity).cloned() {
            let replacement = Client::new(identity, alias, client.addresses)?;
            next_states.stage_client(replacement.clone())?;
            ensure_document_client(&edited, &replacement)?;
        }
        let replacement = DraftChanges::stage_clients(edited, next_states);
        self.draft.publish_replacement(replacement);
        self.invalidate_active_issue_authorizations();
        Ok(())
    }

    /// Delete one explicitly selected peer and its current encrypted record, if
    /// present. File-only vault records and unrelated records are retained.
    pub fn delete_client(&mut self, identity: PublicKey) -> Result<bool, AppError> {
        let saved_document = ConfigDocument::parse(&self.saved.server_config)?;
        let saved_peer_exists = saved_document
            .peers()
            .iter()
            .any(|peer| peer.identity == Some(identity));
        let mut next_states = self.draft.states.clone();
        if saved_peer_exists && self.draft.states.saved().get(&identity).is_none() {
            let peer = saved_document
                .peers()
                .iter()
                .find(|peer| peer.identity == Some(identity))
                .ok_or(AppError::DeletedPeerAddressUnknown)?;
            next_states
                .stage_exact_host_routes(peer.allowed_ips.iter().copied())
                .map_err(|_| AppError::DeletedPeerAddressUnknown)?;
        }
        let edited = ConfigDocument::parse(self.draft.document.delete_client(&identity)?.render())?;
        if edited
            .peers()
            .iter()
            .any(|peer| peer.identity == Some(identity))
        {
            return Err(AppError::InvalidSavedState);
        }
        let mut next_vault = match self.draft.vault.as_ref() {
            Some(vault) => Some(VaultBundle::from_toml(&vault.to_toml()?)?),
            None => None,
        };
        let removed_record = match next_vault.as_mut() {
            Some(vault) => vault.remove_record(identity)?,
            None => false,
        };
        if let Some(vault) = &next_vault {
            vault.to_toml()?;
        }
        next_states.remove_draft_client(&identity);
        let replacement = DraftChanges::stage_clients_and_vault(edited, next_states, next_vault);
        self.draft.publish_replacement(replacement);
        self.invalidate_active_issue_authorizations();
        self.initial_issues.remove(&identity);
        Ok(removed_record)
    }

    /// Stage an initial vault from a prepared read-only source import. It cannot
    /// replace an installed vault and does not change files until Commit.
    pub fn prepare_initial_vault(&mut self, bundle: VaultBundle) -> Result<(), AppError> {
        if self.draft.vault.is_some() || self.saved.vault.is_some() {
            return Err(AppError::VaultAlreadyInstalled);
        }
        bundle.to_toml()?;
        let replacement = DraftChanges::stage_vault(Some(bundle));
        self.draft.publish_replacement(replacement);
        Ok(())
    }

    /// Stage the bundle from M3's read-only initial import result and return
    /// its anomaly report unchanged for the caller to present to the operator.
    pub fn prepare_initial_setup(
        &mut self,
        prepared: PreparedImportSetup,
    ) -> Result<SourceImportReport, AppError> {
        let PreparedImportSetup { bundle, report } = prepared;
        self.prepare_initial_vault(bundle)?;
        Ok(report)
    }

    /// Prepare a password-protected vault and import configured source files
    /// against this session's authoritative document. All results remain in
    /// the in-memory draft until Commit.
    pub fn prepare_initial_setup_from_sources(
        &mut self,
        vault_password: &str,
    ) -> Result<SourceImportReport, AppError> {
        let settings = self.store.resolved_settings_for(&self.saved)?;
        let prepared = crate::vault::source::prepare_initial_setup(
            &settings,
            &self.draft.document,
            vault_password,
        )
        .map_err(AppError::SourceImport)?;
        self.prepare_initial_setup(prepared)
    }

    /// Drop all uncommitted edits and restore the in-memory drafts from the last
    /// successfully installed session snapshot. No files are written.
    pub fn discard_draft(&mut self) -> Result<(), AppError> {
        let installed = self.store.read_saved()?;
        let next_document = ConfigDocument::parse(&installed.server_config)?;
        let next_vault = installed
            .vault
            .as_deref()
            .map(std::str::from_utf8)
            .transpose()
            .map_err(|_| AppError::InvalidSavedState)?
            .map(VaultBundle::from_toml)
            .transpose()?;
        let mut next_states = self.draft.states.clone();
        next_states.discard_draft();
        if let Some(bytes) = &installed.internal_state {
            PersistedState::from_toml(bytes)?.apply_to(&mut next_states)?;
        } else {
            next_states.runtime_knowledge_unknown();
        }
        let next_historical_apply = historical_apply_from_saved(&installed)?;
        let replacement =
            DraftChanges::stage_clients_and_vault(next_document, next_states, next_vault);
        let saved_changed = !same_saved_bytes(&self.saved, &installed);
        self.saved = installed;
        self.draft.publish_replacement(replacement);
        if saved_changed {
            self.verified_saved_projection = None;
        }
        self.historical_apply = next_historical_apply;
        self.initial_issues
            .retain(|_, issue| issue.stage == IssueStage::AwaitingFirstFile);
        retain_matching_issue_map(
            &mut self.initial_issues,
            &self.draft.document,
            self.draft.vault.as_ref(),
        );
        Ok(())
    }

    /// Create the mandatory archive from current installed bytes without
    /// changing the current session or saved files.
    pub fn create_backup(&self, reason: BackupReason) -> Result<std::path::PathBuf, AppError> {
        backups::create_backup(self, reason)
    }

    pub fn create_manual_backup(&self) -> Result<std::path::PathBuf, AppError> {
        self.create_backup(BackupReason::Manual)
    }

    pub fn list_backups(&self) -> Result<Vec<backup::ArchiveSummary>, AppError> {
        backups::list_backups(self)
    }

    /// Reusable mandatory backup boundary for M5 before it invokes restart.
    /// This method only archives saved bytes; it never calls a runtime adapter.
    pub fn create_pre_restart_backup(&mut self) -> Result<std::path::PathBuf, AppError> {
        backups::create_pre_restart_backup(self)
    }

    /// Prepare a read-only preview bound to the exact currently installed generation.
    pub fn preview_restart(&self) -> Result<RestartPreview, AppError> {
        let installed = self.store.read_saved()?;
        if !same_saved_bytes(&installed, &self.saved) {
            return Err(AppError::SavedGenerationChanged);
        }
        let settings = self.store.resolved_settings_for(&installed)?;
        let document = ConfigDocument::parse(&installed.server_config)?;
        if document
            .sections()
            .iter()
            .filter(|section| section.kind == SectionKind::Interface)
            .count()
            != 1
        {
            return Err(AppError::InvalidSavedState);
        }
        if document.has_unsafe_save_config() {
            return Err(AppError::UnsafeSaveConfig);
        }
        let (projection, expected_clients) =
            restart_projection_from_document(&document).map_err(AppError::UnsafeSavedPeers)?;
        let expected_clients =
            expected_clients.filter(|snapshot| snapshot == self.draft.states.saved());
        Ok(RestartPreview {
            saved: clone_saved(&installed),
            interface: settings.interface_name,
            unit: settings.systemd_unit,
            timeout: settings.restart_timeout,
            projection,
            expected_clients,
            has_draft: self.has_draft(),
        })
    }

    fn has_draft(&self) -> bool {
        let vault_differs = match &self.draft.vault {
            Some(vault) => vault.to_toml().map(String::into_bytes).ok() != self.saved.vault,
            None => self.saved.vault.is_some(),
        };
        self.draft.states.draft() != self.draft.states.saved()
            || self.draft.document.render() != self.saved.server_config
            || self
                .draft
                .states
                .address_reservations()
                .pending_host_routes()
                .next()
                .is_some()
            || vault_differs
    }

    /// Confirm or cancel an explicit restart preview. The adapters use only the
    /// saved generation and share one monotonic deadline after backup completion.
    pub fn restart(&mut self, preview: RestartPreview, choice: RestartChoice) -> RestartReport {
        self.restart_with_adapters(
            preview,
            choice,
            service::restart_systemd_unit_report,
            |interface, timeout| {
                runtime::transport::observe_interface(
                    interface,
                    timeout,
                    runtime::netlink::DecodeLimits::default(),
                )
            },
            |store, saved, backup| store.install(saved, backup),
        )
    }

    fn restart_with_adapters(
        &mut self,
        preview: RestartPreview,
        choice: RestartChoice,
        service: impl FnOnce(&str, RestartDeadline) -> RestartExecution,
        runtime_read: impl FnOnce(&str, Duration) -> Result<RuntimeObservation, TransportError>,
        install: impl FnOnce(&SavedStore, &SavedBytes, BackupComplete) -> Result<(), PersistenceError>,
    ) -> RestartReport {
        self.restart_with_adapters_and_clock(
            preview,
            choice,
            service,
            runtime_read,
            install,
            Instant::now,
        )
    }

    /// Test-only adapter boundary for Alpine fixture apply. The supplied
    /// callback must report a completed fixture operation; observation and
    /// verification still use the real Rustix reader and normal persistence
    /// path. This method is not present in production builds.
    #[cfg(test)]
    #[allow(dead_code)] // Consumed by the M8.5 in-container scenario driver.
    pub(crate) fn restart_with_fixture_apply(
        &mut self,
        preview: RestartPreview,
        choice: RestartChoice,
        fixture_apply: impl FnOnce(&str, RestartDeadline) -> RestartExecution,
    ) -> RestartReport {
        self.restart_with_adapters(
            preview,
            choice,
            fixture_apply,
            |interface, timeout| {
                runtime::transport::observe_interface(
                    interface,
                    timeout,
                    runtime::netlink::DecodeLimits::default(),
                )
            },
            |store, saved, backup| store.install(saved, backup),
        )
    }

    fn restart_with_adapters_and_clock(
        &mut self,
        preview: RestartPreview,
        choice: RestartChoice,
        service: impl FnOnce(&str, RestartDeadline) -> RestartExecution,
        runtime_read: impl FnOnce(&str, Duration) -> Result<RuntimeObservation, TransportError>,
        install: impl FnOnce(&SavedStore, &SavedBytes, BackupComplete) -> Result<(), PersistenceError>,
        now: impl Fn() -> Instant,
    ) -> RestartReport {
        if choice == RestartChoice::Cancel {
            return restart_report(RestartStage::Cancelled, None, None, false, false, false);
        }
        self.active_restart_attempt = None;
        if self.has_draft() != preview.has_draft
            || (preview.has_draft && choice != RestartChoice::DiscardDraftAndRestart)
            || (!preview.has_draft && choice == RestartChoice::DiscardDraftAndRestart)
        {
            return restart_report(
                RestartStage::Preparation,
                Some(RestartFailureKind::InvalidOrStaleSavedGeneration),
                None,
                false,
                false,
                false,
            );
        }
        let installed = match self.store.read_saved() {
            Ok(saved)
                if same_saved_bytes(&saved, &preview.saved)
                    && same_saved_bytes(&saved, &self.saved) =>
            {
                saved
            }
            _ => {
                self.active_restart_attempt = None;
                return restart_report(
                    RestartStage::Preparation,
                    Some(RestartFailureKind::InvalidOrStaleSavedGeneration),
                    None,
                    false,
                    false,
                    false,
                );
            }
        };
        let settings = match self.store.resolved_settings_for(&installed) {
            Ok(settings) => settings,
            Err(_) => {
                return restart_report(
                    RestartStage::Preparation,
                    Some(RestartFailureKind::InvalidOrStaleSavedGeneration),
                    None,
                    false,
                    false,
                    false,
                );
            }
        };
        let document = match ConfigDocument::parse(&installed.server_config) {
            Ok(document) => document,
            Err(_) => {
                return restart_report(
                    RestartStage::Preparation,
                    Some(RestartFailureKind::InvalidOrStaleSavedGeneration),
                    None,
                    false,
                    false,
                    false,
                );
            }
        };
        if document
            .sections()
            .iter()
            .filter(|section| section.kind == SectionKind::Interface)
            .count()
            != 1
        {
            return restart_report(
                RestartStage::Preparation,
                Some(RestartFailureKind::InvalidOrStaleSavedGeneration),
                None,
                false,
                false,
                false,
            );
        }
        if document.has_unsafe_save_config() {
            return restart_report(
                RestartStage::Preparation,
                Some(RestartFailureKind::UnsafeSaveConfig),
                None,
                false,
                false,
                false,
            );
        }
        let (projection, expected_clients) = match restart_projection_from_document(&document) {
            Ok(projection) => projection,
            Err(_) => {
                return restart_report(
                    RestartStage::Preparation,
                    Some(RestartFailureKind::UnsupportedSavedShape),
                    None,
                    false,
                    false,
                    false,
                );
            }
        };
        let expected_clients =
            expected_clients.filter(|snapshot| snapshot == self.draft.states.saved());
        if settings.interface_name != preview.interface
            || settings.systemd_unit != preview.unit
            || settings.restart_timeout != preview.timeout
            || projection != preview.projection
            || expected_clients != preview.expected_clients
        {
            return restart_report(
                RestartStage::Preparation,
                Some(RestartFailureKind::InvalidOrStaleSavedGeneration),
                None,
                false,
                false,
                false,
            );
        }
        let historical_apply = match historical_apply_from_saved(&installed) {
            Ok(status) => status,
            Err(_) => {
                return restart_report(
                    RestartStage::Preparation,
                    Some(RestartFailureKind::InvalidOrStaleSavedGeneration),
                    None,
                    false,
                    false,
                    false,
                );
            }
        };
        let backup_path = match backup::create_archive(
            self.store.archives_directory(),
            BackupReason::PreRestart,
            historical_apply,
            &installed,
        ) {
            Ok(path) => path,
            Err(_) => {
                self.active_restart_attempt = None;
                return restart_report(
                    RestartStage::Backup,
                    Some(RestartFailureKind::BackupFailed),
                    None,
                    false,
                    false,
                    false,
                );
            }
        };

        let id = self.next_restart_attempt;
        let Some(next_id) = id.checked_add(1) else {
            return restart_report(
                RestartStage::Preparation,
                Some(RestartFailureKind::InvalidOrStaleSavedGeneration),
                Some(backup_path),
                false,
                false,
                false,
            );
        };
        self.next_restart_attempt = next_id;
        self.active_restart_attempt = Some(id);
        if choice == RestartChoice::DiscardDraftAndRestart && self.discard_draft().is_err() {
            self.active_restart_attempt = None;
            return restart_report(
                RestartStage::Preparation,
                Some(RestartFailureKind::DraftDiscardFailed),
                Some(backup_path),
                false,
                false,
                false,
            );
        }

        self.draft.states.runtime_knowledge_unknown();
        let deadline = RestartDeadline::new(now(), settings.restart_timeout);
        let execution = service(&settings.systemd_unit, deadline);
        let job = execution.outcome;
        let submitted = execution.submitted;
        let service_phase = execution.phase;
        if job != RestartOutcome::Succeeded {
            self.active_restart_attempt = None;
            let may_complete = submitted
                && !matches!(
                    job,
                    RestartOutcome::Failed(
                        service::RestartFailure::JobFailed
                            | service::RestartFailure::JobDependency
                            | service::RestartFailure::JobTimedOut
                            | service::RestartFailure::JobCanceled
                            | service::RestartFailure::JobSkipped
                            | service::RestartFailure::JobResultUnknown
                    )
                );
            let mut report = restart_report(
                RestartStage::Service,
                Some(RestartFailureKind::ServiceFailed),
                Some(backup_path),
                submitted,
                may_complete,
                submitted,
            );
            report.service_failure = match job {
                RestartOutcome::Failed(failure) => Some(failure),
                RestartOutcome::Waiting | RestartOutcome::Succeeded => None,
            };
            report.service_phase = Some(service_phase);
            report.systemd_unit = Some(settings.systemd_unit);
            return report;
        }
        let remaining = deadline.remaining_at(now());
        if remaining.is_zero() {
            self.active_restart_attempt = None;
            return restart_report(
                RestartStage::RuntimeRead,
                Some(RestartFailureKind::RuntimeTimeout),
                Some(backup_path),
                true,
                false,
                true,
            );
        }
        let observation = match runtime_read(&settings.interface_name, remaining) {
            Ok(observation) => observation,
            Err(error) => {
                self.active_restart_attempt = None;
                return restart_report(
                    RestartStage::RuntimeRead,
                    Some(match error {
                        TransportError::NoDevice => RestartFailureKind::RuntimeNoDevice,
                        TransportError::PermissionDenied => {
                            RestartFailureKind::RuntimePermissionDenied
                        }
                        TransportError::Malformed => RestartFailureKind::RuntimeMalformed,
                        TransportError::Transport => RestartFailureKind::RuntimeTransport,
                        TransportError::Timeout => RestartFailureKind::RuntimeTimeout,
                        TransportError::LimitExceeded => RestartFailureKind::RuntimeLimitExceeded,
                    }),
                    Some(backup_path),
                    true,
                    false,
                    true,
                );
            }
        };
        if deadline.is_expired_at(now()) {
            self.active_restart_attempt = None;
            return restart_report(
                RestartStage::Verification,
                Some(RestartFailureKind::RuntimeTimeout),
                Some(backup_path),
                true,
                false,
                true,
            );
        }
        if runtime::compare_peers(&projection, &settings.interface_name, &observation)
            != TechnicalMatch::Match
        {
            self.active_restart_attempt = None;
            return restart_report(
                RestartStage::Verification,
                Some(RestartFailureKind::RuntimeMismatch),
                Some(backup_path),
                true,
                false,
                true,
            );
        }
        let Some(verified_at) = OffsetDateTime::now_utc()
            .replace_nanosecond(0)
            .ok()
            .and_then(|timestamp| timestamp.format(&Rfc3339).ok())
        else {
            self.active_restart_attempt = None;
            return restart_report(
                RestartStage::Persistence,
                Some(RestartFailureKind::VerificationPersistenceFailed),
                Some(backup_path),
                true,
                false,
                true,
            );
        };
        let attempt = RestartAttempt {
            id,
            saved: clone_saved(&installed),
        };
        let marked =
            self.mark_verified_with_attempt(attempt, expected_clients, verified_at, install);
        if marked.is_err() {
            self.active_restart_attempt = None;
            return restart_report(
                RestartStage::Persistence,
                Some(RestartFailureKind::VerificationPersistenceFailed),
                Some(backup_path),
                true,
                false,
                true,
            );
        }
        restart_report(
            RestartStage::Complete,
            None,
            Some(backup_path),
            true,
            false,
            false,
        )
    }

    /// Validate a selected archive without changing saved files or the draft.
    /// The returned value carries the exact validated bytes used at confirmation.
    pub fn preview_restore(&self, file_name: &str) -> Result<RestorePreview, AppError> {
        restore::preview_restore(self, file_name)
    }

    /// Explicitly confirm a previously previewed restore. The pre-restore
    /// archive is finalized before the journaled full replacement begins.
    pub fn confirm_restore(
        &mut self,
        preview: RestorePreview,
    ) -> Result<std::path::PathBuf, AppError> {
        restore::confirm_restore(self, preview, |store, saved, _backup| {
            store.install(saved, BackupComplete(()))
        })
    }

    #[cfg(test)]
    fn confirm_restore_with_install(
        &mut self,
        preview: RestorePreview,
        install: impl FnOnce(&SavedStore, &SavedBytes, BackupComplete) -> Result<(), PersistenceError>,
    ) -> Result<std::path::PathBuf, AppError> {
        restore::confirm_restore(self, preview, install)
    }

    /// Persist applied state only with the one-use authorization produced by
    /// the active confirmed restart after full technical verification.
    fn mark_verified_with_attempt(
        &mut self,
        attempt: RestartAttempt,
        observed_management_snapshot: Option<Snapshot>,
        verified_at_utc: String,
        install: impl FnOnce(&SavedStore, &SavedBytes, BackupComplete) -> Result<(), PersistenceError>,
    ) -> Result<(), AppError> {
        if self.active_restart_attempt != Some(attempt.id) {
            return Err(AppError::PreRestartBackupRequired);
        }
        let installed = self.store.read_saved()?;
        if !same_saved_bytes(&installed, &self.saved)
            || !same_saved_bytes(&installed, &attempt.saved)
        {
            return Err(AppError::SavedGenerationChanged);
        }
        let mut next_states = self.draft.states.clone();
        next_states.prepare_technically_verified_result(observed_management_snapshot)?;
        let mut persisted = match &installed.internal_state {
            Some(bytes) => PersistedState::from_toml(bytes)?,
            None => PersistedState::new(
                next_states
                    .reserved_addresses()
                    .iter()
                    .map(ToString::to_string),
                None,
            )?,
        };
        persisted.reserved_addresses = next_states
            .reserved_addresses()
            .iter()
            .map(ToString::to_string)
            .collect();
        let historical_apply = HistoricalApplyStatus::Verified {
            verified_at_utc: verified_at_utc.clone(),
        };
        persisted.last_verified_at_utc = Some(verified_at_utc);
        let mut proposed = installed;
        proposed.internal_state = Some(persisted.to_toml()?);
        self.store.validate_saved(&proposed)?;
        if let Err(error) = install(&self.store, &proposed, BackupComplete(())) {
            self.invalidate_active_issue_authorizations();
            match self.store.read_saved() {
                Ok(current) => {
                    let document = ConfigDocument::parse(&current.server_config).ok();
                    let vault = current
                        .vault
                        .as_deref()
                        .and_then(|bytes| std::str::from_utf8(bytes).ok())
                        .and_then(|text| VaultBundle::from_toml(text).ok());
                    if let Some(document) = document {
                        retain_matching_issue_map(
                            &mut self.initial_issues,
                            &document,
                            vault.as_ref(),
                        );
                    } else {
                        self.initial_issues.clear();
                    }
                }
                Err(_) => self.initial_issues.clear(),
            }
            return Err(error.into());
        }
        self.saved = proposed;
        self.draft.states = next_states;
        self.verified_saved_projection =
            Some(SavedPeerProjection::from_document(&self.draft.document));
        self.historical_apply = historical_apply;
        self.active_restart_attempt = None;
        Ok(())
    }

    /// Commit current configuration, vault, and reservations. The archive is
    /// complete before `SavedStore::install` receives its capability. In-memory
    /// saved state advances only after the adapter reports full success.
    pub fn commit(&mut self) -> Result<std::path::PathBuf, AppError> {
        self.commit_with_adapters(backup::create_archive, |store, proposed, _backup| {
            store.install(proposed, BackupComplete(()))
        })
    }

    fn commit_with_adapters(
        &mut self,
        create_backup: impl FnOnce(
            &std::path::Path,
            BackupReason,
            HistoricalApplyStatus,
            &SavedBytes,
        ) -> Result<std::path::PathBuf, BackupError>,
        install: impl FnOnce(&SavedStore, &SavedBytes, BackupComplete) -> Result<(), PersistenceError>,
    ) -> Result<std::path::PathBuf, AppError> {
        commit::commit(self, create_backup, install)
    }
}

fn safe_archive_name(name: &str) -> bool {
    name.starts_with("wireguard-admin-")
        && name.ends_with(".tar")
        && name
            .bytes()
            .all(|byte| byte.is_ascii_alphanumeric() || matches!(byte, b'-' | b'.'))
}

fn historical_apply_from_saved(saved: &SavedBytes) -> Result<HistoricalApplyStatus, AppError> {
    let Some(bytes) = &saved.internal_state else {
        return Ok(HistoricalApplyStatus::Unknown);
    };
    Ok(
        match PersistedState::from_toml(bytes)?.last_verified_at_utc {
            Some(verified_at_utc) => HistoricalApplyStatus::Verified { verified_at_utc },
            None => HistoricalApplyStatus::Unknown,
        },
    )
}

fn same_saved_bytes(left: &SavedBytes, right: &SavedBytes) -> bool {
    left.settings == right.settings
        && left.server_config == right.server_config
        && left.internal_state == right.internal_state
        && left.vault == right.vault
}

fn clone_saved(saved: &SavedBytes) -> SavedBytes {
    SavedBytes {
        settings: saved.settings.clone(),
        server_config: saved.server_config.clone(),
        internal_state: saved.internal_state.clone(),
        vault: saved.vault.clone(),
    }
}

fn retain_matching_issue_map(
    issues: &mut BTreeMap<PublicKey, InitialIssue>,
    document: &ConfigDocument,
    vault: Option<&VaultBundle>,
) {
    issues.retain(|identity, issue| {
        if issue.stage == IssueStage::PendingDraft {
            return true;
        }
        vault
            .and_then(|vault| issue_context(document, vault, *identity).ok())
            .is_some_and(|actual| actual == issue.context)
    });
}

fn promote_matching_issue_map(
    issues: &mut BTreeMap<PublicKey, InitialIssue>,
    document: &ConfigDocument,
    vault: Option<&VaultBundle>,
) {
    issues.retain(|identity, issue| {
        let matches = vault
            .and_then(|vault| issue_context(document, vault, *identity).ok())
            .is_some_and(|actual| actual == issue.context);
        if matches && issue.stage == IssueStage::PendingDraft {
            issue.stage = IssueStage::AwaitingFirstFile;
        }
        matches
    });
}

fn issue_context(
    document: &ConfigDocument,
    vault: &VaultBundle,
    identity: PublicKey,
) -> Result<IssueContext, AppError> {
    let matching = document
        .peers()
        .iter()
        .filter(|peer| {
            peer.identity == Some(identity) || peer.public_key_candidates.contains(&identity)
        })
        .collect::<Vec<_>>();
    let [peer] = matching.as_slice() else {
        return Err(AppError::FirstIssueUnavailable);
    };
    if peer.identity != Some(identity) || !peer.issues.is_empty() {
        return Err(AppError::FirstIssueUnavailable);
    }
    // Alias/admin comments are descriptive metadata; only WireGuard directives
    // bind first-issue authority, so renames do not invalidate the creation.
    let peer_directives = document
        .source_slice(peer.section)
        .ok_or(AppError::FirstIssueUnavailable)?
        .lines()
        .map(str::trim)
        .filter(|line| !line.is_empty() && !line.starts_with(['#', ';']))
        .collect::<Vec<_>>()
        .join("\n");
    let encrypted_record = vault
        .record_context(identity)
        .ok_or(AppError::FirstIssueUnavailable)?
        .to_owned();
    Ok(IssueContext {
        peer_directives,
        encrypted_record,
    })
}

fn server_interface_addresses(document: &ConfigDocument) -> Result<Vec<IpAddr>, AppError> {
    let interfaces = document
        .sections()
        .iter()
        .filter(|section| section.kind == SectionKind::Interface)
        .collect::<Vec<_>>();
    let [interface] = interfaces.as_slice() else {
        return Err(AppError::InvalidSavedState);
    };
    let source = document
        .source_slice(interface.span)
        .ok_or(AppError::InvalidSavedState)?;
    let mut addresses = Vec::new();
    let mut address_directive_seen = false;
    for line in source.lines() {
        let trimmed = line.trim_matches(|ch: char| ch.is_ascii_whitespace());
        if trimmed.is_empty() || trimmed.starts_with(['#', ';']) {
            continue;
        }
        let Some((name, value)) = trimmed.split_once('=') else {
            continue;
        };
        if !name.trim().eq_ignore_ascii_case("Address") {
            continue;
        }
        if address_directive_seen {
            return Err(AppError::InvalidSavedState);
        }
        address_directive_seen = true;
        for item in value.split(',') {
            let network = item
                .trim()
                .parse::<ipnet::IpNet>()
                .map_err(|_| AppError::InvalidSavedState)?;
            addresses.push(match network {
                ipnet::IpNet::V4(network) => IpAddr::V4(network.addr()),
                ipnet::IpNet::V6(network) => IpAddr::V6(network.addr()),
            });
        }
    }
    if addresses.is_empty() {
        return Err(AppError::InvalidSavedState);
    }
    Ok(addresses)
}

fn document_host_addresses(document: &ConfigDocument) -> Vec<IpAddr> {
    document
        .peers()
        .iter()
        .flat_map(|peer| peer.allowed_ips.iter())
        .filter_map(|network| match network {
            ipnet::IpNet::V4(network) if network.prefix_len() == 32 => {
                Some(IpAddr::V4(network.addr()))
            }
            ipnet::IpNet::V6(network) if network.prefix_len() == 128 => {
                Some(IpAddr::V6(network.addr()))
            }
            _ => None,
        })
        .collect()
}

fn restart_projection_from_document(
    document: &ConfigDocument,
) -> Result<(SavedPeerProjection, Option<Snapshot>), Vec<RestartDiagnostic>> {
    use crate::wireguard::{DocumentIssue, PeerIssue};

    let mut diagnostics = Vec::new();
    for issue in document.issues() {
        let (line, reason) = match issue {
            DocumentIssue::MalformedSectionHeader { line } => (*line, "malformed section header"),
            DocumentIssue::DirectiveOutsideSection { line } => {
                (*line, "directive appears outside a section")
            }
            DocumentIssue::MalformedDirective { line } => (*line, "malformed directive"),
            // Managed metadata is descriptive and does not affect the technical
            // peer set used for runtime verification.
            DocumentIssue::ManagedMetadata(_) => continue,
        };
        diagnostics.push(RestartDiagnostic {
            identity: None,
            section_line: Some(line),
            reason,
        });
    }

    for peer in document.peers() {
        let identity = peer
            .identity
            .or_else(|| peer.public_key_candidates.first().copied());
        for issue in &peer.issues {
            let reason = match issue {
                PeerIssue::MissingPublicKey => Some("peer is missing a public key"),
                PeerIssue::MalformedPublicKey { .. } => Some("peer has a malformed public key"),
                PeerIssue::DuplicatePublicKeyField { .. } => {
                    Some("peer has duplicate public key fields")
                }
                PeerIssue::DuplicatePeerIdentity { .. } => {
                    Some("public key is used by multiple peer sections")
                }
                PeerIssue::MalformedAllowedIp { .. } => {
                    Some("peer has a malformed AllowedIPs item")
                }
                PeerIssue::UnsupportedAllowedIpShape { .. } | PeerIssue::MissingIpv4HostRoute => {
                    None
                }
            };
            if let Some(reason) = reason {
                diagnostics.push(RestartDiagnostic {
                    identity,
                    section_line: Some(peer.section_line),
                    reason,
                });
            }
        }
    }

    let projection = SavedPeerProjection::from_document(document);
    if (projection.document_unverifiable
        || !projection.unverifiable_peer_indices.is_empty()
        || !projection.duplicate_public_keys.is_empty())
        && diagnostics.is_empty()
    {
        diagnostics.push(RestartDiagnostic {
            identity: None,
            section_line: None,
            reason: "saved peer set is not uniquely verifiable",
        });
    }
    if !diagnostics.is_empty() {
        return Err(diagnostics);
    }

    let mut clients = Vec::with_capacity(document.peers().len());
    for peer in document.peers() {
        let Some(identity) = peer.identity else {
            return Err(vec![RestartDiagnostic {
                identity: None,
                section_line: Some(peer.section_line),
                reason: "peer identity is unavailable",
            }]);
        };
        let Ok(client) = document.project_client(&identity) else {
            clients.clear();
            break;
        };
        clients.push(client);
    }
    let management_snapshot = (clients.len() == document.peers().len())
        .then(|| Snapshot::new(clients).ok())
        .flatten();
    Ok((projection, management_snapshot))
}

fn restart_report(
    stage: RestartStage,
    failure: Option<RestartFailureKind>,
    backup_path: Option<std::path::PathBuf>,
    restart_submitted: bool,
    restart_may_still_complete: bool,
    manual_recovery_required: bool,
) -> RestartReport {
    RestartReport {
        stage,
        failure,
        service_failure: None,
        service_phase: None,
        systemd_unit: None,
        backup_path,
        restart_submitted,
        restart_may_still_complete,
        manual_recovery_required,
    }
}

fn snapshot_from_document(document: &ConfigDocument) -> Snapshot {
    let mut snapshot = Snapshot::default();
    for client in document.peers().iter().filter_map(|peer| {
        let identity = peer.identity?;
        document.project_client(&identity).ok()
    }) {
        let _ = snapshot.insert(client);
    }
    snapshot
}

fn ensure_document_client(document: &ConfigDocument, client: &Client) -> Result<(), AppError> {
    if document.project_client(&client.identity)? != *client {
        return Err(AppError::InvalidSavedState);
    }
    Ok(())
}

#[derive(Debug, Error)]
pub enum AppError {
    #[error("saved state is invalid or incompatible with this session")]
    InvalidSavedState,
    #[error("a vault is already installed")]
    VaultAlreadyInstalled,
    #[error("the installed vault identity cannot be replaced")]
    VaultIdentityChange,
    #[error("a vault must be installed before creating a client")]
    VaultMissingForCreation,
    #[error("a new client must have both IPv4 and IPv6 addresses")]
    NewClientMustBeDualStack,
    #[error("first file issuance is not authorized for this client in this session")]
    FirstIssueUnavailable,
    #[error("first-issue authorization identifiers are exhausted for this session")]
    IssueAuthorizationExhausted,
    #[error("client key generation failed")]
    KeyGenerationFailed,
    #[error("the selected backup name is invalid")]
    InvalidArchiveSelection,
    #[error("the selected unsupported peer has no exact host route to reserve safely")]
    DeletedPeerAddressUnknown,
    #[error("runtime verification cannot be recorded without a completed pre-restart backup")]
    PreRestartBackupRequired,
    #[error("wg-quick SaveConfig may overwrite the saved server configuration during restart")]
    UnsafeSaveConfig,
    #[error("saved peer cannot be represented by the client management model")]
    UnsupportedSavedShape,
    #[error("saved server configuration cannot be verified safely: {0:?}")]
    UnsafeSavedPeers(Vec<RestartDiagnostic>),
    #[error("installed saved bytes changed after this session opened")]
    SavedGenerationChanged,
    #[error(transparent)]
    Backup(#[from] BackupError),
    #[error(transparent)]
    Persistence(#[from] PersistenceError),
    #[error(transparent)]
    Vault(#[from] VaultError),
    #[error(transparent)]
    Document(#[from] DocumentError),
    #[error(transparent)]
    Edit(#[from] EditError),
    #[error(transparent)]
    Domain(#[from] DomainError),
    #[error(transparent)]
    Delivery(#[from] crate::delivery::DeliveryError),
    #[error(transparent)]
    FileOutput(#[from] FileOutputError),
    #[error(transparent)]
    SourceImport(#[from] SourceImportError),
}

#[cfg(test)]
mod tests {
    use std::ffi::OsStr;
    use std::fs;
    use std::net::{Ipv4Addr, Ipv6Addr};
    use std::os::unix::fs::PermissionsExt;
    use std::path::Path;
    use std::time::{Duration, Instant};

    use super::{
        AppError, Application, FileOutputError, FirstIssueAttempt, FirstIssueDeliveryFailure,
        FirstIssueDeliveryOutcome, FirstIssueRetry, RestartChoice, RestartFailureKind,
        RestartStage, clone_saved, snapshot_from_document,
    };
    use crate::backup::{ArchiveCheckpoint, create_archive_with_hook};
    use crate::backup::{BackupReason, HistoricalApplyStatus, create_archive, preview_archive};
    use crate::config::SettingsFile;
    use crate::delivery::qr::QrError;
    use crate::domain::{
        AddressAvailability, AddressFamily, ApplyStatus, Client, ClientAddresses, ClientStates,
        DomainError, PublicKey, Snapshot, allocate_ipv4, allocate_ipv6,
    };
    use crate::persistence::{
        BackupComplete, InstallCheckpoint, PersistedState, PersistenceError, SavedStore,
    };
    use crate::runtime::transport::TransportError;
    use crate::runtime::{
        InterfaceObservation, Observed, PeerSetCompleteness, RuntimeObservation, RuntimePeer,
        RuntimePeerSet,
    };
    use crate::service::{RestartExecution, RestartFailure, RestartOutcome};
    use crate::vault::{VaultBundle, WireGuardPrivateKey};
    use crate::wireguard::ConfigDocument;

    const SETTINGS: &str = r#"
interface_name = "wg0"
server_config_path = "server.conf"
client_source_directory = "clients"
server_endpoint = "vpn.example.test:51820"
ipv4_allocation_range = "10.20.0.0/24"
ipv6_allocation_range = "fd20::/64"
dns_addresses = ["10.20.0.1"]
systemd_unit = "wg-quick@wg0.service"
restart_timeout_seconds = 30
"#;

    #[test]
    fn restore_settings_projection_reports_changed_fields_without_exposing_values() {
        let proposed = SETTINGS.replace("vpn.example.test:51820", "vpn-new.example.test:51820");
        let fields = super::settings_fields_changed(SETTINGS.as_bytes(), proposed.as_bytes());
        assert_eq!(fields, ["server endpoint"]);
        let malformed = super::settings_fields_changed(SETTINGS.as_bytes(), b"invalid = [");
        assert_eq!(malformed, ["settings file"]);
    }

    fn setup(
        root: &Path,
        archive_as_file: bool,
    ) -> (SavedStore, ClientStates, PublicKey, WireGuardPrivateKey) {
        fs::create_dir_all(root).expect("temporary root should be created");
        let settings_file = SettingsFile::parse_toml(SETTINGS)
            .expect("settings fixture parses")
            .validate()
            .expect("settings fixture validates");
        let resolved = settings_file.resolve_paths(root);
        fs::write(root.join("wireguard-admin.toml"), SETTINGS).expect("settings installed");
        let secret = WireGuardPrivateKey::generate().expect("synthetic peer key");
        let server_secret = WireGuardPrivateKey::generate().expect("synthetic server key");
        let key = secret.public_key();
        let server = format!(
            "[Interface]\nPrivateKey = {}\nAddress = 10.20.0.1/24, fd20::1/64\n\n# admin note\n[Peer]\nPublicKey = {key}\nAllowedIPs = 10.20.0.2/32, fd20::2/128\n",
            server_secret.to_base64()
        );
        fs::write(root.join("server.conf"), server.as_bytes()).expect("server installed");
        fs::set_permissions(root.join("server.conf"), fs::Permissions::from_mode(0o600))
            .expect("server fixture private");
        if archive_as_file {
            fs::create_dir_all(root.join("Backup")).expect("backup root created");
            fs::write(root.join("Backup/archives"), b"block archive directory").expect("blocker");
        }
        let saved_client = Client::new(
            key,
            "legacy-view",
            ClientAddresses {
                ipv4: Ipv4Addr::new(10, 20, 0, 2),
                ipv6: Some("fd20::2".parse::<Ipv6Addr>().expect("IPv6 fixture")),
            },
        )
        .expect("state client valid");
        let snapshot = Snapshot::new([saved_client]).expect("snapshot valid");
        let states = ClientStates::new(snapshot.clone(), Some(snapshot), ApplyStatus::Verified)
            .expect("initial applied state valid");
        let store = SavedStore::new(root, resolved).expect("saved store mapping valid");
        (store, states, key, secret)
    }

    fn test_mark_verified(
        app: &mut Application,
        observed: Snapshot,
        verified_at: String,
    ) -> Result<(), AppError> {
        app.create_pre_restart_backup()?;
        let id = app.next_restart_attempt;
        app.next_restart_attempt += 1;
        app.active_restart_attempt = Some(id);
        let attempt = super::RestartAttempt {
            id,
            saved: clone_saved(&app.saved),
        };
        app.mark_verified_with_attempt(
            attempt,
            Some(observed),
            verified_at,
            |store, saved, backup| store.install(saved, backup),
        )
    }

    fn prepare_restartable(root: &Path) -> (Application, PublicKey) {
        let (store, states, key, _) = setup(root, false);
        let mut app = Application::open(store, states).expect("application opens");
        app.rename_client(key, "restart fixture")
            .expect("install managed metadata");
        app.commit().expect("restart fixture commits");
        (app, key)
    }

    fn setup_with_vault(root: &Path) -> Application {
        let (store, states, _, _) = setup(root, false);
        let mut app = Application::open(store, states).expect("application opens");
        app.prepare_initial_vault(
            VaultBundle::create("synthetic vault password").expect("synthetic vault"),
        )
        .expect("vault stages");
        app.commit().expect("initial vault commits");
        app
    }

    fn observed_runtime(app: &Application) -> RuntimeObservation {
        let records = app.document().peers().iter().map(|peer| {
            let identity = peer.identity.expect("synthetic peer identity");
            (
                identity,
                RuntimePeer {
                    allowed_ips: Observed::Available(peer.allowed_ips.clone()),
                    last_handshake: Observed::Available(None),
                    received_bytes: Observed::Available(0),
                    transmitted_bytes: Observed::Available(0),
                },
            )
        });
        RuntimeObservation {
            observed_at: None,
            interface: InterfaceObservation::Present {
                name: "wg0".to_owned(),
                peers: RuntimePeerSet::from_records(PeerSetCompleteness::Complete, records),
            },
        }
    }

    #[test]
    fn new_client_preparation_is_transactional_and_uncommitted_keys_cannot_issue() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let before_document = app.document().render().to_vec();
        let before_saved = clone_saved(app.saved_bytes());
        let before_draft = app.states().draft().clone();
        let before_records = app.vault().expect("vault exists").record_count();
        let existing_identity = app
            .states()
            .saved()
            .clients()
            .next()
            .expect("legacy client exists")
            .identity;
        assert!(matches!(
            app.deliver_first_issue(existing_identity, FirstIssueAttempt::Initial, |_| Ok::<
                _,
                ((), _),
            >(
                ()
            )),
            Err(AppError::FirstIssueUnavailable)
        ));

        assert!(matches!(
            app.prepare_new_client("invalid\nalias", None, None),
            Err(AppError::Domain(_))
        ));
        assert_eq!(app.document().render(), before_document);
        assert_eq!(app.saved_bytes().server_config, before_saved.server_config);
        assert_eq!(app.states().draft(), &before_draft);
        assert_eq!(
            app.vault().expect("vault exists").record_count(),
            before_records
        );

        let identity = app
            .prepare_new_client("shared alias", None, Some("2026-10-20T00:00:00Z"))
            .expect("new client is staged");
        assert!(app.initial_issues.contains_key(&identity));
        assert!(matches!(
            app.prepare_new_client("invalid\nalias", None, None),
            Err(AppError::Domain(_))
        ));
        assert!(app.initial_issues.contains_key(&identity));
        let client = app.states().draft().get(&identity).expect("draft client");
        assert_eq!(client.addresses.ipv4, Ipv4Addr::new(10, 20, 0, 3));
        assert!(client.addresses.ipv6.is_some());
        assert_eq!(app.states().saved().get(&identity), None);
        assert_eq!(
            app.vault().expect("vault exists").record_count(),
            before_records + 1
        );
        assert!(matches!(
            app.deliver_first_issue(identity, FirstIssueAttempt::Initial, |_| Ok::<_, ((), _)>(
                ()
            )),
            Err(AppError::FirstIssueUnavailable)
        ));
    }

    #[test]
    fn missing_vault_after_client_preparation_does_not_publish_any_draft_or_issue() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let mut app = Application::open(store, states).expect("application opens");
        let before_document = app.document().render().to_vec();
        let before_draft = app.states().draft().clone();

        assert!(matches!(
            app.prepare_new_client("missing vault", None, None),
            Err(AppError::VaultMissingForCreation)
        ));

        assert_eq!(app.document().render(), before_document);
        assert_eq!(app.states().draft(), &before_draft);
        assert!(app.vault().is_none());
        assert!(app.initial_issues.is_empty());
    }

    #[test]
    fn selected_file_import_uses_the_existing_vault_draft_without_saving() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let source_directory = root.path().join("clients");
        fs::create_dir_all(&source_directory).expect("source directory");
        fs::write(
            source_directory.join("invalid.conf"),
            b"not a client config\n",
        )
        .expect("synthetic invalid source file");
        let saved_vault = app.saved_bytes().vault.clone();
        let draft_records = app.vault().expect("vault exists").record_count();

        let report = app
            .import_selected_file(OsStr::new("invalid.conf"))
            .expect("invalid selected file is reported rather than fatal");

        assert!(report.scan_complete);
        assert!(matches!(
            report.candidates[0].1,
            crate::vault::import::CandidateStatus::Invalid(_)
        ));
        assert_eq!(
            app.vault().expect("vault remains present").record_count(),
            draft_records
        );
        assert_eq!(app.saved_bytes().vault, saved_vault);
    }

    #[test]
    fn selected_import_error_keeps_vault_and_pending_issue_unchanged() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("pending import", None, None)
            .expect("client stages");
        let before_document = app.document().render().to_vec();
        let before_states = app.states().clone();
        let before_vault = app.vault().expect("vault exists").to_toml().unwrap();

        assert!(matches!(
            app.import_selected_file(OsStr::new("../invalid.conf")),
            Err(AppError::SourceImport(
                crate::vault::source::SourceImportError::InvalidSelection
            ))
        ));

        assert_eq!(app.document().render(), before_document);
        assert_eq!(app.states(), &before_states);
        assert_eq!(
            app.vault()
                .expect("vault remains present")
                .to_toml()
                .unwrap(),
            before_vault
        );
        assert!(app.initial_issues.contains_key(&identity));
    }

    #[test]
    fn manual_addresses_reject_occupied_and_out_of_range_without_partial_staging() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let before_document = app.document().render().to_vec();
        let before_records = app.vault().expect("vault exists").record_count();

        assert!(matches!(
            app.prepare_new_client(
                "occupied",
                Some(ClientAddresses {
                    ipv4: Ipv4Addr::new(10, 20, 0, 2),
                    ipv6: Some("fd20::3".parse().expect("IPv6")),
                }),
                None,
            ),
            Err(AppError::Domain(
                crate::domain::DomainError::AddressUnavailable
            ))
        ));
        assert!(matches!(
            app.prepare_new_client(
                "outside",
                Some(ClientAddresses {
                    ipv4: Ipv4Addr::new(10, 21, 0, 3),
                    ipv6: Some("fd20::3".parse().expect("IPv6")),
                }),
                None,
            ),
            Err(AppError::Domain(
                crate::domain::DomainError::AddressOutsideRange
            ))
        ));
        assert_eq!(app.document().render(), before_document);
        assert_eq!(
            app.vault().expect("vault exists").record_count(),
            before_records
        );
    }

    #[test]
    fn commit_failure_keeps_pending_issue_and_successful_retry_authorizes_it() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("retry", None, None)
            .expect("client stages");
        let archives = root.path().join("Backup/archives");
        let moved_archives = root.path().join("Backup/archives-saved");
        fs::rename(&archives, &moved_archives).expect("move archive directory");
        fs::write(&archives, b"block archive creation").expect("install blocker");

        assert!(matches!(app.commit(), Err(AppError::Backup(_))));
        assert!(matches!(
            app.deliver_first_issue(identity, FirstIssueAttempt::Initial, |_| Ok::<_, ((), _)>(
                ()
            )),
            Err(AppError::FirstIssueUnavailable)
        ));

        fs::remove_file(&archives).expect("remove temporary blocker");
        fs::rename(&moved_archives, &archives).expect("restore archive directory");
        assert!(matches!(
            app.commit_with_adapters(crate::backup::create_archive, |_, _, _| Err(
                PersistenceError::RecoveryRequired
            ),),
            Err(AppError::Persistence(PersistenceError::RecoveryRequired))
        ));
        assert!(matches!(
            app.deliver_first_issue(identity, FirstIssueAttempt::Initial, |_| Ok::<_, ((), _)>(
                ()
            )),
            Err(AppError::FirstIssueUnavailable)
        ));
        app.commit().expect("retry commits");
        let mut payload_was_available = false;
        let result = app
            .deliver_first_issue(identity, FirstIssueAttempt::Initial, |payload| {
                payload_was_available = !payload.is_empty();
                Ok::<_, ((), _)>(())
            })
            .expect("committed creation can issue");
        assert!(payload_was_available);
        assert!(matches!(result, FirstIssueDeliveryOutcome::Delivered(())));
    }

    #[test]
    fn unrelated_rename_and_verified_restart_preserve_independent_first_issues() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let first = app
            .prepare_new_client("same alias", None, None)
            .expect("first client stages");
        let second = app
            .prepare_new_client("same alias", None, None)
            .expect("second client stages");
        assert_ne!(first, second);
        app.commit().expect("both clients commit");
        let unrelated = app
            .states()
            .saved()
            .clients()
            .find(|client| client.alias == "legacy-view")
            .expect("saved client")
            .identity;
        app.rename_client(unrelated, "renamed unrelated client")
            .expect("unrelated rename stages");
        app.commit().expect("unrelated rename commits");

        let snapshot = snapshot_from_document(app.document());
        test_mark_verified(&mut app, snapshot, "2026-10-20T01:00:00Z".to_owned())
            .expect("verified restart state persists");
        app.deliver_first_issue(first, FirstIssueAttempt::Initial, |payload| {
            assert!(!payload.is_empty());
            Ok::<_, ((), _)>(())
        })
        .expect("first client remains eligible and its file succeeds");
        assert!(matches!(
            app.deliver_first_issue(first, FirstIssueAttempt::Initial, |_| Ok::<_, ((), _)>(())),
            Err(AppError::FirstIssueUnavailable)
        ));
        app.deliver_first_issue(second, FirstIssueAttempt::Initial, |payload| {
            assert!(!payload.is_empty());
            Ok::<_, ((), _)>(())
        })
        .expect("second client's outstanding capability remains independent");
        assert!(matches!(
            app.deliver_first_issue(second, FirstIssueAttempt::Initial, |_| Ok::<_, ((), _)>(())),
            Err(AppError::FirstIssueUnavailable)
        ));
    }

    #[test]
    fn first_issue_authorization_is_single_flight_and_success_consumes_it() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("one-use", None, None)
            .expect("client stages");
        app.commit().expect("client commits");

        let delivered = app
            .deliver_first_issue(identity, FirstIssueAttempt::Initial, |_| {
                Ok::<_, ((), _)>(())
            })
            .expect("first authorization succeeds");
        assert!(matches!(
            delivered,
            FirstIssueDeliveryOutcome::Delivered(())
        ));
        assert!(matches!(
            app.deliver_first_issue(identity, FirstIssueAttempt::Initial, |_| Ok::<_, ((), _)>(
                ()
            )),
            Err(AppError::FirstIssueUnavailable)
        ));
        // The initial operation already consumed eligibility on success.
    }

    #[test]
    fn committed_first_issue_publishes_selected_file_and_consumes_eligibility() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("file delivery", None, None)
            .expect("client stages");
        app.commit().expect("client commits");

        let destination_path = root.path().join("chosen/output/client.conf");
        let destination = app
            .prepare_first_issue_destination(&destination_path)
            .expect("explicit output path is safe");
        assert!(matches!(
            app.deliver_first_issue_file(identity, FirstIssueAttempt::Initial, destination)
                .expect("authorized file is delivered"),
            FirstIssueDeliveryOutcome::Delivered(delivery) if delivery.activation_warning
        ));
        let metadata = fs::metadata(&destination_path).expect("client file exists");
        assert_eq!(metadata.permissions().mode() & 0o777, 0o600);
        assert!(
            fs::read(&destination_path)
                .expect("client configuration readable")
                .starts_with(b"[Interface]\nPrivateKey = ")
        );
        let retry_path = root.path().join("chosen/output/retry.conf");
        let retry = app
            .prepare_first_issue_destination(&retry_path)
            .expect("new explicit path remains safe");
        assert!(matches!(
            app.deliver_first_issue_file(identity, FirstIssueAttempt::Initial, retry),
            Err(AppError::FirstIssueUnavailable)
        ));
        assert!(!retry_path.exists());
    }

    #[test]
    fn file_and_qr_share_payload_and_qr_failure_still_consumes_first_issue() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("file and QR", None, None)
            .expect("client stages");
        app.commit().expect("client commits");
        let path = root.path().join("chosen/client.conf");
        let destination = app
            .prepare_first_issue_destination(&path)
            .expect("destination prepares");

        let result = app
            .deliver_first_issue_file_and_qr_with(
                identity,
                FirstIssueAttempt::Initial,
                destination,
                |payload| {
                    assert!(
                        payload.as_bytes() == fs::read(&path).expect("published file is readable")
                    );
                    Err(QrError::CapacityExceeded)
                },
            )
            .expect("file action completes");
        let FirstIssueDeliveryOutcome::Delivered(delivery) = result else {
            panic!("file publication succeeds independently of QR encoding");
        };
        assert!(delivery.activation_warning);
        assert!(matches!(delivery.qr, Err(QrError::CapacityExceeded)));
        let retry = app
            .prepare_first_issue_destination(root.path().join("chosen/retry.conf"))
            .expect("retry destination prepares");
        assert!(matches!(
            app.deliver_first_issue_file_and_qr(identity, FirstIssueAttempt::Initial, retry),
            Err(AppError::FirstIssueUnavailable)
        ));
    }

    #[test]
    fn successful_file_qr_action_encodes_the_published_bytes() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("successful QR", None, None)
            .expect("client stages");
        app.commit().expect("client commits");
        let path = root.path().join("chosen/client.conf");
        let destination = app
            .prepare_first_issue_destination(&path)
            .expect("destination prepares");

        let result = app
            .deliver_first_issue_file_and_qr_with(
                identity,
                FirstIssueAttempt::Initial,
                destination,
                |payload| {
                    assert!(
                        payload.as_bytes() == fs::read(&path).expect("published file is readable")
                    );
                    crate::delivery::qr::encode_payload(payload)
                },
            )
            .expect("file and QR action completes");
        let FirstIssueDeliveryOutcome::Delivered(delivery) = result else {
            panic!("file publication succeeds");
        };
        assert!(delivery.activation_warning);
        let matrix = delivery.qr.expect("QR encodes");
        assert!((29..=185).contains(&matrix.side()));
    }

    #[test]
    fn first_issue_warning_tracks_verified_saved_generation_for_file_and_qr() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let legacy = app
            .states()
            .saved()
            .clients()
            .next()
            .expect("legacy client")
            .identity;
        app.rename_client(legacy, "legacy-view")
            .expect("write authoritative alias metadata");
        let identities = (0..4)
            .map(|_| {
                app.prepare_new_client("activation", None, None)
                    .expect("client stages")
            })
            .collect::<Vec<_>>();
        app.commit().expect("clients commit");

        for (index, identity) in identities[..2].iter().copied().enumerate() {
            let path = root.path().join(format!("unapplied-{index}.conf"));
            let destination = app
                .prepare_first_issue_destination(path)
                .expect("destination prepares");
            if index == 0 {
                let result = app
                    .deliver_first_issue_file(identity, FirstIssueAttempt::Initial, destination)
                    .expect("file delivery succeeds");
                assert!(matches!(
                    result,
                    FirstIssueDeliveryOutcome::Delivered(delivery) if delivery.activation_warning
                ));
            } else {
                let result = app
                    .deliver_first_issue_file_and_qr(
                        identity,
                        FirstIssueAttempt::Initial,
                        destination,
                    )
                    .expect("file and QR delivery succeeds");
                assert!(matches!(
                    result,
                    FirstIssueDeliveryOutcome::Delivered(delivery) if delivery.activation_warning
                ));
            }
        }

        let saved_snapshot = app.states().saved().clone();
        test_mark_verified(&mut app, saved_snapshot, "2026-10-21T00:00:00Z".to_owned())
            .expect("same saved generation is verified applied");
        for (index, identity) in identities[2..].iter().copied().enumerate() {
            let path = root.path().join(format!("applied-{index}.conf"));
            let destination = app
                .prepare_first_issue_destination(path)
                .expect("destination prepares");
            if index == 0 {
                let result = app
                    .deliver_first_issue_file(identity, FirstIssueAttempt::Initial, destination)
                    .expect("file delivery succeeds");
                assert!(matches!(
                    result,
                    FirstIssueDeliveryOutcome::Delivered(delivery) if !delivery.activation_warning
                ));
            } else {
                let result = app
                    .deliver_first_issue_file_and_qr(
                        identity,
                        FirstIssueAttempt::Initial,
                        destination,
                    )
                    .expect("file and QR delivery succeeds");
                assert!(matches!(
                    result,
                    FirstIssueDeliveryOutcome::Delivered(delivery) if !delivery.activation_warning
                ));
            }
        }
    }

    #[test]
    fn historical_verified_timestamp_does_not_suppress_reissue_warning_after_reopen() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("history warning", None, None)
            .expect("client stages");
        app.commit().expect("client commits");
        let saved = app.states().saved().clone();
        test_mark_verified(&mut app, saved, "2026-10-21T00:00:00Z".to_owned())
            .expect("saved generation verified");

        let mut runtime_unknown = app.states().clone();
        runtime_unknown.runtime_knowledge_unknown();
        let reopened = Application::open(app.store.clone(), runtime_unknown)
            .expect("application reopens with unknown runtime");
        let destination = reopened
            .prepare_first_issue_destination(root.path().join("history-reissue.conf"))
            .expect("destination prepares");
        let result = reopened
            .reissue_client_file(identity, "synthetic vault password", destination, true)
            .expect("password-authorized reissue succeeds");
        assert!(result.activation_warning);
        assert!(result.qr.is_some_and(|qr| qr.is_ok()));
    }

    #[test]
    fn qr_is_not_attempted_when_mandatory_file_publication_fails() {
        use std::sync::atomic::{AtomicBool, Ordering};

        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("file failure", None, None)
            .expect("client stages");
        app.commit().expect("client commits");
        let path = root.path().join("chosen/existing.conf");
        fs::create_dir_all(path.parent().expect("parent exists")).expect("parent creates");
        fs::write(&path, b"existing synthetic bytes").expect("existing target writes");
        let destination = app
            .prepare_first_issue_destination(&path)
            .expect("existing destination prepares");
        let qr_called = AtomicBool::new(false);
        let result = app
            .deliver_first_issue_file_and_qr_with(
                identity,
                FirstIssueAttempt::Initial,
                destination,
                |_| {
                    qr_called.store(true, Ordering::SeqCst);
                    Err(QrError::EncodingFailed)
                },
            )
            .expect("file failure is reported as an operation result");
        assert!(!qr_called.load(Ordering::SeqCst));
        assert!(matches!(
            result,
            FirstIssueDeliveryOutcome::Failed {
                error: FileOutputError::OverwriteDeclined,
                retry: FirstIssueRetry::Available,
                ..
            }
        ));
        assert_eq!(
            fs::read(&path).expect("existing file retained"),
            b"existing synthetic bytes"
        );
    }

    #[test]
    fn published_file_is_reported_when_saved_store_bookkeeping_fails() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("bookkeeping fault", None, None)
            .expect("client stages");
        app.commit().expect("client commits");
        let saved_server_config = app.saved_bytes().server_config.clone();

        let output_path = root.path().join("delivered/client.conf");
        let destination = app
            .prepare_first_issue_destination(&output_path)
            .expect("destination prepares");
        let result = app.deliver_first_issue_with_warning(
            identity,
            FirstIssueAttempt::Initial,
            |payload, activation_warning| {
                crate::delivery::files::publish(destination, payload).map_err(|error| {
                    let failure = match error {
                        FileOutputError::PublicationUncertain => {
                            FirstIssueDeliveryFailure::PublicationUncertain
                        }
                        FileOutputError::ManualCleanupRequired => {
                            FirstIssueDeliveryFailure::CleanupRequired
                        }
                        _ => FirstIssueDeliveryFailure::BeforePublication,
                    };
                    (error, failure)
                })?;
                // Fault injection after definite publication and before the
                // application's post-publication saved-state read.
                fs::remove_file(root.path().join("server.conf"))
                    .expect("inject saved-store read failure");
                Ok::<
                    _,
                    (
                        crate::delivery::files::FileOutputError,
                        FirstIssueDeliveryFailure,
                    ),
                >(activation_warning)
            },
        );

        assert!(matches!(
            result,
            Ok(
                FirstIssueDeliveryOutcome::PublishedButBookkeepingUncertain {
                    value: true,
                    error: AppError::Persistence(PersistenceError::Io(_)),
                    ..
                }
            )
        ));
        assert!(
            fs::read(&output_path)
                .expect("published file remains available")
                .starts_with(b"[Interface]\nPrivateKey = ")
        );
        fs::write(root.path().join("server.conf"), saved_server_config)
            .expect("restore the synthetic saved config");
        fs::set_permissions(
            root.path().join("server.conf"),
            fs::Permissions::from_mode(0o600),
        )
        .expect("keep restored config private");
        assert!(matches!(
            app.deliver_first_issue(identity, FirstIssueAttempt::Initial, |_| {
                Ok::<_, ((), FirstIssueDeliveryFailure)>(())
            }),
            Err(AppError::FirstIssueUnavailable)
        ));
    }

    #[test]
    fn failed_file_publication_can_retry_in_a_different_directory() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("retryable file", None, None)
            .expect("client stages");
        app.commit().expect("client commits");

        let first_directory = root.path().join("first-selection");
        fs::create_dir(&first_directory).expect("first output directory");
        let first_path = first_directory.join("client.conf");
        let first = app
            .prepare_first_issue_destination(&first_path)
            .expect("first selection prepares");
        fs::remove_dir(&first_directory).expect("simulate directory removal before publish");
        fs::write(&first_directory, b"blocker").expect("replace directory with a file");
        let failed = app
            .deliver_first_issue_file(identity, FirstIssueAttempt::Initial, first)
            .expect("file failure is recorded for retry");
        assert!(matches!(
            failed,
            FirstIssueDeliveryOutcome::Failed {
                retry: FirstIssueRetry::Available,
                ..
            }
        ));
        fs::remove_file(&first_directory).expect("remove synthetic blocker");

        let second_path = root.path().join("new-selection/client.conf");
        let second = app
            .prepare_first_issue_destination(&second_path)
            .expect("new selection prepares");
        assert!(matches!(
            app.deliver_first_issue_file(
                identity,
                FirstIssueAttempt::Retry {
                    confirm_possible_overwrite: false,
                    confirm_manual_cleanup: false,
                },
                second,
            )
            .expect("same-session retry succeeds"),
            FirstIssueDeliveryOutcome::Delivered(delivery) if delivery.activation_warning
        ));
        assert!(second_path.exists());
    }

    #[test]
    fn failed_first_delivery_requires_consuming_capability_before_retry() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("retry-output", None, None)
            .expect("client stages");
        app.commit().expect("client commits");

        let failed = app
            .deliver_first_issue(identity, FirstIssueAttempt::Initial, |_| {
                Err::<(), _>(("write failed", FirstIssueDeliveryFailure::BeforePublication))
            })
            .expect("pre-publication failure returns eligibility");
        assert!(matches!(
            failed,
            FirstIssueDeliveryOutcome::Failed {
                error: "write failed",
                retry: FirstIssueRetry::Available,
                activation_warning: true,
            }
        ));

        let retry = app
            .deliver_first_issue(
                identity,
                FirstIssueAttempt::Retry {
                    confirm_possible_overwrite: false,
                    confirm_manual_cleanup: false,
                },
                |_| {
                    Err::<(), _>((
                        "sync uncertain",
                        FirstIssueDeliveryFailure::PublicationUncertain,
                    ))
                },
            )
            .expect("pre-publication retry needs no overwrite confirmation");
        assert!(matches!(
            retry,
            FirstIssueDeliveryOutcome::Failed {
                error: "sync uncertain",
                retry: FirstIssueRetry::OverwriteConfirmationRequired,
                activation_warning: true,
            }
        ));
        assert!(matches!(
            app.deliver_first_issue(
                identity,
                FirstIssueAttempt::Retry {
                    confirm_possible_overwrite: false,
                    confirm_manual_cleanup: false,
                },
                |_| Ok::<_, ((), _)>(())
            ),
            Err(AppError::FirstIssueUnavailable)
        ));
        app.deliver_first_issue(
            identity,
            FirstIssueAttempt::Retry {
                confirm_possible_overwrite: true,
                confirm_manual_cleanup: false,
            },
            |_| Ok::<_, ((), _)>(()),
        )
        .expect("possible existing output requires explicit overwrite confirmation");
        assert!(matches!(
            app.deliver_first_issue(
                identity,
                FirstIssueAttempt::Retry {
                    confirm_possible_overwrite: true,
                    confirm_manual_cleanup: false,
                },
                |_| Ok::<_, ((), _)>(())
            ),
            Err(AppError::FirstIssueUnavailable)
        ));
    }

    #[test]
    fn temporary_cleanup_failure_requires_manual_cleanup_before_first_issue_retry() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("cleanup recovery", None, None)
            .expect("client stages");
        app.commit().expect("client commits");

        let failed = app
            .deliver_first_issue(identity, FirstIssueAttempt::Initial, |_| {
                Err::<(), _>((
                    "cleanup required",
                    FirstIssueDeliveryFailure::CleanupRequired,
                ))
            })
            .expect("cleanup failure is reported as recovery-required");
        assert!(matches!(
            failed,
            FirstIssueDeliveryOutcome::Failed {
                error: "cleanup required",
                retry: FirstIssueRetry::ManualCleanupRequired,
                activation_warning: true,
            }
        ));
        assert!(matches!(
            app.deliver_first_issue(
                identity,
                FirstIssueAttempt::Retry {
                    confirm_possible_overwrite: false,
                    confirm_manual_cleanup: false,
                },
                |_| Ok::<_, ((), FirstIssueDeliveryFailure)>(())
            ),
            Err(AppError::FirstIssueUnavailable)
        ));
        app.deliver_first_issue(
            identity,
            FirstIssueAttempt::Retry {
                confirm_possible_overwrite: false,
                confirm_manual_cleanup: true,
            },
            |_| Ok::<_, ((), FirstIssueDeliveryFailure)>(()),
        )
        .expect("manual cleanup acknowledgement permits same-session retry");
    }

    #[test]
    fn uncertain_first_file_publication_retains_warning_and_skips_qr() {
        use std::sync::atomic::{AtomicBool, Ordering};

        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("uncertain publication", None, None)
            .expect("client stages");
        app.commit().expect("client commits");

        let file_path = root.path().join("file-only/client.conf");
        let file_destination = app
            .prepare_first_issue_destination(&file_path)
            .expect("file destination prepares");
        let file_result = app
            .deliver_first_issue_file_with(
                identity,
                FirstIssueAttempt::Initial,
                file_destination,
                |_, _| Err(FileOutputError::PublicationUncertain),
            )
            .expect("uncertain publication is reported as an operation result");
        assert!(matches!(
            file_result,
            FirstIssueDeliveryOutcome::Failed {
                error: FileOutputError::PublicationUncertain,
                retry: FirstIssueRetry::OverwriteConfirmationRequired,
                activation_warning: true,
            }
        ));

        // The uncertain result requires an explicit overwrite-confirmed retry.
        let qr_path = root.path().join("file-and-qr/client.conf");
        let qr_destination = app
            .prepare_first_issue_destination(&qr_path)
            .expect("QR file destination prepares");
        let qr_called = AtomicBool::new(false);
        let qr_result = app
            .deliver_first_issue_file_and_qr_with_publisher(
                identity,
                FirstIssueAttempt::Retry {
                    confirm_possible_overwrite: true,
                    confirm_manual_cleanup: false,
                },
                qr_destination,
                |_, _| Err(FileOutputError::PublicationUncertain),
                |_| {
                    qr_called.store(true, Ordering::SeqCst);
                    Err(QrError::EncodingFailed)
                },
            )
            .expect("uncertain retry is reported as an operation result");
        assert!(!qr_called.load(Ordering::SeqCst));
        assert!(matches!(
            qr_result,
            FirstIssueDeliveryOutcome::Failed {
                error: FileOutputError::PublicationUncertain,
                retry: FirstIssueRetry::OverwriteConfirmationRequired,
                activation_warning: true,
            }
        ));
    }

    #[test]
    fn deleted_first_issue_never_invokes_publication_closure() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let identity = app
            .prepare_new_client("delete-capability", None, None)
            .expect("client stages");
        app.commit().expect("client commits");
        assert!(app.delete_client(identity).expect("client deletes"));
        let mut writer_called = false;
        assert!(matches!(
            app.deliver_first_issue(identity, FirstIssueAttempt::Initial, |_| {
                writer_called = true;
                Ok::<_, ((), _)>(())
            }),
            Err(AppError::FirstIssueUnavailable)
        ));
        assert!(
            !writer_called,
            "deleted client bytes are never handed to a writer"
        );
    }

    #[test]
    fn deletion_and_discard_revoke_only_session_bound_initial_material() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let pending = app
            .prepare_new_client("discard", None, None)
            .expect("client stages");
        app.discard_draft().expect("draft discards");
        assert!(matches!(
            app.deliver_first_issue(
                pending,
                FirstIssueAttempt::Initial,
                |_| Ok::<_, ((), _)>(())
            ),
            Err(AppError::FirstIssueUnavailable)
        ));

        let deleted = app
            .prepare_new_client("delete", None, None)
            .expect("second client stages");
        app.commit().expect("second client commits");
        assert!(app.delete_client(deleted).expect("client deletes"));
        app.commit().expect("deletion commits");
        assert!(matches!(
            app.deliver_first_issue(
                deleted,
                FirstIssueAttempt::Initial,
                |_| Ok::<_, ((), _)>(())
            ),
            Err(AppError::FirstIssueUnavailable)
        ));
    }

    #[test]
    fn backup_failure_preserves_installed_files_and_draft() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, key, _) = setup(root.path(), true);
        let before = store.read_saved().expect("installed bytes readable");
        let mut app = Application::open(store.clone(), states).expect("application opens");
        app.rename_client(key, "new alias")
            .expect("rename is staged");

        assert!(matches!(app.commit(), Err(AppError::Backup(_))));
        assert_eq!(
            store
                .read_saved()
                .expect("saved remains readable")
                .server_config,
            before.server_config
        );
        assert!(
            String::from_utf8_lossy(app.document().render())
                .contains("# wg-admin:alias=bmV3IGFsaWFz")
        );
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        assert_eq!(
            app.states().saved().get(&key).expect("saved peer").alias,
            "legacy-view"
        );
    }

    #[test]
    fn injected_archive_and_install_failures_preserve_bytes_and_session_saved_state() {
        let root = tempfile::tempdir().expect("temporary directory");
        let (store, states, key, _) = setup(root.path(), false);
        let original = store.read_saved().expect("original bytes");
        for point in [
            ArchiveCheckpoint::Write,
            ArchiveCheckpoint::Sync,
            ArchiveCheckpoint::Publish,
            ArchiveCheckpoint::TemporaryCleanup,
            ArchiveCheckpoint::DirectorySync,
        ] {
            let mut app = Application::open(store.clone(), states.clone()).expect("open");
            app.rename_client(key, "draft alias").expect("stage alias");
            let result = app.commit_with_adapters(
                |directory, reason, history, saved| {
                    create_archive_with_hook(directory, reason, history, saved, |current| {
                        if current == point {
                            Err(std::io::Error::other("archive fault"))
                        } else {
                            Ok(())
                        }
                    })
                },
                |store, proposed, _backup| store.install(proposed, BackupComplete(())),
            );
            assert!(result.is_err());
            let on_disk = store.read_saved().expect("saved files stay readable");
            assert_eq!(on_disk.server_config, original.server_config);
            assert_eq!(app.saved_bytes().server_config, original.server_config);
            assert_eq!(app.states().saved().get(&key).unwrap().alias, "legacy-view");
            assert_eq!(app.states().draft().get(&key).unwrap().alias, "draft alias");
        }

        for point in [
            InstallCheckpoint::StageWrite(1),
            InstallCheckpoint::StageSync(1),
            InstallCheckpoint::Replaced(1),
        ] {
            let mut app = Application::open(store.clone(), states.clone()).expect("open");
            app.rename_client(key, "draft alias").expect("stage alias");
            let result = app.commit_with_adapters(create_archive, |store, proposed, _backup| {
                store.install_with_hook(proposed, |current| {
                    if current == point {
                        Err(std::io::Error::other("install fault"))
                    } else {
                        Ok(())
                    }
                })
            });
            assert!(result.is_err());
            let on_disk = store.read_saved().expect("reopen recovers transaction");
            assert_eq!(on_disk.settings, original.settings);
            assert_eq!(on_disk.server_config, original.server_config);
            assert_eq!(on_disk.internal_state, original.internal_state);
            assert_eq!(on_disk.vault, original.vault);
            assert_eq!(app.saved_bytes().server_config, original.server_config);
            assert_eq!(app.states().saved().get(&key).unwrap().alias, "legacy-view");
            assert_eq!(app.states().draft().get(&key).unwrap().alias, "draft alias");
        }
    }

    #[test]
    fn commit_advances_saved_state_without_applying_and_backup_contains_old_bytes() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, key, _) = setup(root.path(), false);
        let original = store.read_saved().expect("installed bytes readable");
        let mut app = Application::open(store.clone(), states).expect("application opens");
        app.rename_client(key, "new alias")
            .expect("rename is staged");
        let archive = app.commit().expect("commit should complete");

        let saved = store.read_saved().expect("new bytes readable");
        assert!(
            String::from_utf8_lossy(&saved.server_config).contains("# wg-admin:alias=bmV3IGFsaWFz")
        );
        assert!(
            !String::from_utf8_lossy(&original.server_config)
                .contains("# wg-admin:alias=bmV3IGFsaWFz")
        );
        assert_eq!(
            app.states().saved().get(&key).expect("saved peer").alias,
            "new alias"
        );
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        assert!(app.states().applied_snapshot().is_some());
        let backup = preview_archive(&archive).expect("pre-commit backup parses");
        assert_eq!(backup.reason, BackupReason::PreCommit);
        assert_eq!(backup.saved_bytes.server_config, original.server_config);
        assert_eq!(backup.saved_bytes.settings, original.settings);
        assert!(String::from_utf8_lossy(&saved.server_config).contains("# admin note\n"));
    }

    #[test]
    fn unchanged_commit_preserves_verified_apply_knowledge() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let mut app = Application::open(store, states).expect("application opens");
        let observed = app.states().saved().clone();
        test_mark_verified(&mut app, observed, "2026-10-29T12:00:00Z".to_owned())
            .expect("synthetic verification is published");
        assert_eq!(app.states().applied(), &ApplyStatus::Verified);

        app.commit().expect("unchanged commit completes");

        assert_eq!(app.states().applied(), &ApplyStatus::Verified);
        assert_eq!(app.states().applied_snapshot(), Some(app.states().saved()));
    }

    #[test]
    fn unchanged_commit_preserves_unavailable_apply_knowledge() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let mut app = Application::open(store, states).expect("application opens");
        app.draft.states.runtime_knowledge_unavailable();

        app.commit().expect("unchanged commit completes");

        assert_eq!(app.states().applied(), &ApplyStatus::Unavailable);
    }

    #[test]
    fn changed_saved_snapshot_demotes_verified_apply_knowledge_on_commit() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, key, _) = setup(root.path(), false);
        let mut app = Application::open(store, states).expect("application opens");
        let observed = app.states().saved().clone();
        test_mark_verified(
            &mut app,
            observed.clone(),
            "2026-10-29T12:00:00Z".to_owned(),
        )
        .expect("synthetic verification is published");
        app.rename_client(key, "changed saved peer")
            .expect("peer change is staged");

        app.commit().expect("changed commit completes");

        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        assert_eq!(app.states().applied_snapshot(), Some(&observed));
        assert_ne!(app.states().saved(), &observed);
    }

    #[test]
    fn discard_restores_draft_without_writing_installed_bytes() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, key, _) = setup(root.path(), false);
        let original = store.read_saved().expect("installed bytes readable");
        let mut app = Application::open(store.clone(), states).expect("application opens");
        app.rename_client(key, "temporary")
            .expect("rename is staged");
        app.discard_draft().expect("draft can be discarded");

        assert_eq!(
            store.read_saved().expect("saved readable").server_config,
            original.server_config
        );
        assert!(!String::from_utf8_lossy(app.document().render()).contains("temporary"));
        assert_eq!(app.states().draft(), app.states().saved());
    }

    #[test]
    fn discard_parse_failure_preserves_every_live_draft_component_and_issue() {
        let root = tempfile::tempdir().expect("temp directory");
        let mut app = setup_with_vault(root.path());
        let issue = app
            .prepare_new_client("discard failure", None, None)
            .expect("new client stages");
        let before_saved = clone_saved(app.saved_bytes());
        let before_document = app.document().render().to_vec();
        let before_states = app.states().clone();
        let before_vault = app.vault().expect("vault exists").to_toml().unwrap();
        fs::write(root.path().join("server.conf"), [0xff]).expect("corrupt synthetic saved file");

        assert!(app.discard_draft().is_err());

        assert!(super::same_saved_bytes(app.saved_bytes(), &before_saved));
        assert_eq!(app.document().render(), before_document);
        assert_eq!(app.states(), &before_states);
        assert_eq!(
            app.vault()
                .expect("vault remains present")
                .to_toml()
                .unwrap(),
            before_vault
        );
        assert!(app.initial_issues.contains_key(&issue));
    }

    #[test]
    fn initial_vault_is_prepared_then_installed_only_after_commit() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states).expect("application opens");
        let secret = WireGuardPrivateKey::generate().expect("synthetic secret");
        let bundle = VaultBundle::create("synthetic password").expect("synthetic vault");
        app.prepare_initial_vault(bundle).expect("vault is staged");
        assert!(store.read_saved().expect("saved readable").vault.is_none());
        app.commit().expect("initial vault commit");
        let installed = store.read_saved().expect("saved readable");
        let text = std::str::from_utf8(installed.vault.as_deref().expect("vault installed"))
            .expect("vault UTF-8");
        assert_eq!(
            VaultBundle::from_toml(text)
                .expect("vault loads")
                .record_count(),
            0
        );
        assert_eq!(secret.public_key().as_bytes().len(), 32);
    }

    #[test]
    fn deletion_only_removes_selected_current_record_and_retains_other_records() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, selected, selected_secret) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states).expect("application opens");
        let mut bundle = VaultBundle::create("synthetic password").expect("vault setup");
        bundle
            .encrypt_record(selected, &selected_secret)
            .expect("selected record");
        let retained_secret = WireGuardPrivateKey::generate().expect("secret");
        let retained = retained_secret.public_key();
        bundle
            .encrypt_record(retained, &retained_secret)
            .expect("file-only record");
        app.prepare_initial_vault(bundle).expect("vault staged");
        app.commit().expect("initial vault commit");

        assert!(
            app.delete_client(selected)
                .expect("selected record removed")
        );
        app.commit().expect("deletion committed");
        let installed = store.read_saved().expect("saved readable");
        let bundle = VaultBundle::from_toml(
            std::str::from_utf8(installed.vault.as_deref().expect("vault")).expect("utf8"),
        )
        .expect("vault parses");
        assert!(!bundle.contains_record(selected));
        assert!(bundle.contains_record(retained));
        let state = PersistedState::from_toml(
            installed
                .internal_state
                .as_deref()
                .expect("state is installed on commit"),
        )
        .expect("state parses");
        assert!(state.reserved_addresses.contains(&"10.20.0.2".to_owned()));
        assert!(state.reserved_addresses.contains(&"fd20::2".to_owned()));

        let reopened_states = ClientStates::new(Snapshot::default(), None, ApplyStatus::Unknown)
            .expect("empty supported snapshot is valid");
        let reopened = Application::open(store, reopened_states).expect("session reopens");
        assert_eq!(reopened.states().applied(), &ApplyStatus::Unknown);
        assert!(
            reopened
                .states()
                .reserved_addresses()
                .contains(&"10.20.0.2".parse().expect("IPv4 address"))
        );
        assert!(
            reopened
                .states()
                .reserved_addresses()
                .contains(&"fd20::2".parse().expect("IPv6 address"))
        );
    }

    #[test]
    fn deletion_of_unprojectable_peer_persists_its_exact_host_route_reservation() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let unsupported = PublicKey::from_bytes([9; 32]);
        let mut server =
            fs::read_to_string(root.path().join("server.conf")).expect("server fixture reads");
        server.push_str(&format!(
            "\n# legacy peer remains outside the narrow state projection\n[Peer]\nPublicKey = {unsupported}\nAllowedIPs = 10.20.0.9/32\n"
        ));
        fs::write(root.path().join("server.conf"), server).expect("server fixture updated");
        let mut app = Application::open(store.clone(), states).expect("application opens");

        assert!(
            !app.delete_client(unsupported)
                .expect("selected server-only peer deleted")
        );
        assert!(app.states().reserved_addresses().is_empty());
        app.commit()
            .expect("commit preserves unsupported peer address");

        let saved = store.read_saved().expect("saved bytes readable");
        let state = PersistedState::from_toml(
            saved
                .internal_state
                .as_deref()
                .expect("state is installed on commit"),
        )
        .expect("reservation state parses");
        assert_eq!(state.reserved_addresses, ["10.20.0.9"]);
        assert!(!String::from_utf8_lossy(&saved.server_config).contains(&unsupported.to_string()));
    }

    #[test]
    fn deletion_of_unprojectable_peer_with_broad_route_fails_without_draft_change() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let unsupported = PublicKey::from_bytes([9; 32]);
        let mut server =
            fs::read_to_string(root.path().join("server.conf")).expect("server fixture reads");
        server.push_str(&format!(
            "\n[Peer]\nPublicKey = {unsupported}\nAllowedIPs = fd20::/64\n"
        ));
        fs::write(root.path().join("server.conf"), server).expect("server fixture updated");
        let mut app = Application::open(store.clone(), states).expect("application opens");
        let before = app.document().render().to_vec();

        assert!(matches!(
            app.delete_client(unsupported),
            Err(super::AppError::DeletedPeerAddressUnknown)
        ));
        assert_eq!(app.document().render(), before);
        assert_eq!(
            store.read_saved().expect("saved readable").server_config,
            before
        );
    }

    #[test]
    fn existing_vault_identity_cannot_be_replaced() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let mut app = Application::open(store, states).expect("application opens");
        app.prepare_initial_vault(VaultBundle::create("first password").expect("vault"))
            .expect("first vault prepared");
        app.commit().expect("first vault installed");
        assert!(matches!(
            app.prepare_initial_vault(VaultBundle::create("second password").expect("vault")),
            Err(AppError::VaultAlreadyInstalled)
        ));
    }

    #[test]
    fn state_file_round_trip_keeps_pending_addresses() {
        let state = PersistedState::new(["10.20.0.9".to_owned()], None).expect("reservation valid");
        assert!(
            PersistedState::from_toml(&state.to_toml().expect("state serializes"))
                .expect("state reloads")
                .reserved_addresses
                .contains(&"10.20.0.9".to_owned())
        );
    }

    #[test]
    fn preview_is_read_only_and_confirm_restores_without_unlocking_vault() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, key, _) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states).expect("application opens");
        app.rename_client(key, "Laptop")
            .expect("managed alias is staged");
        app.commit().expect("managed alias commit");
        app.prepare_initial_vault(VaultBundle::create("synthetic password").expect("vault"))
            .expect("vault staged");
        app.commit().expect("vault commit");
        let saved = store.read_saved().expect("saved bytes");
        let selected = create_archive(
            store.archives_directory(),
            BackupReason::Manual,
            HistoricalApplyStatus::Unknown,
            &saved,
        )
        .expect("selected archive");
        app.rename_client(key, "draft alias").expect("draft rename");
        let before = store.read_saved().expect("installed bytes before preview");
        let preview = app
            .preview_restore(selected.file_name().unwrap().to_str().unwrap())
            .expect("archive preview validates");
        assert_eq!(
            store
                .read_saved()
                .expect("preview is read only")
                .server_config,
            before.server_config
        );
        assert_eq!(
            app.states().draft().get(&key).expect("draft client").alias,
            "draft alias"
        );

        // Replacing the selected path after preview cannot change the confirmed bytes.
        fs::write(&selected, b"changed after preview").expect("mutate selected archive path");
        app.confirm_restore(preview)
            .expect("restore uses previewed bytes");
        assert!(!String::from_utf8_lossy(app.document().render()).contains("draft alias"));
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        assert!(app.vault().is_some());
        assert!(app.states().saved().get(&key).is_some());
    }

    #[test]
    fn partial_restore_failure_preserves_session_and_pre_restore_backup_then_reopens_to_old_set() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, key, _) = setup(root.path(), false);
        let server_config_path = SettingsFile::parse_toml(SETTINGS)
            .unwrap()
            .validate()
            .unwrap()
            .resolve_paths(root.path())
            .server_config_path;
        let mut app = Application::open(store.clone(), states).expect("application opens");
        let selected_saved = store.read_saved().expect("initial saved bytes");
        let selected = create_archive(
            store.archives_directory(),
            BackupReason::Manual,
            HistoricalApplyStatus::Unknown,
            &selected_saved,
        )
        .expect("selected restore archive");

        app.rename_client(key, "currently saved")
            .expect("stage current alias");
        app.commit().expect("save current alias");
        let before_restore = store.read_saved().expect("current saved bytes");
        app.rename_client(key, "draft survives failed restore")
            .expect("stage draft");
        let applied_before = *app.states().applied();
        let preview = app
            .preview_restore(selected.file_name().unwrap().to_str().unwrap())
            .expect("selected archive preview");

        let result = app.confirm_restore_with_install(preview, |store, saved, _backup| {
            store.install_with_hook(saved, |point| {
                if point == InstallCheckpoint::Replaced(2) {
                    Err(std::io::Error::other("interrupt after restore replacement"))
                } else {
                    Ok(())
                }
            })
        });
        assert!(matches!(
            result,
            Err(AppError::Persistence(PersistenceError::RecoveryRequired))
        ));

        // The server file was replaced before the injected failure. The app
        // session still exposes its old saved snapshot and retains its draft.
        assert_eq!(
            fs::read(&server_config_path).unwrap(),
            selected_saved.server_config
        );
        assert_eq!(app.saved_bytes().settings, before_restore.settings);
        assert_eq!(
            app.saved_bytes().server_config,
            before_restore.server_config
        );
        assert_eq!(
            app.saved_bytes().internal_state,
            before_restore.internal_state
        );
        assert_eq!(app.saved_bytes().vault, before_restore.vault);
        assert_eq!(
            app.states().saved().get(&key).unwrap().alias,
            "currently saved"
        );
        assert_eq!(
            app.states().draft().get(&key).unwrap().alias,
            "draft survives failed restore"
        );
        assert_eq!(app.states().applied(), &applied_before);

        // A failed rollback remains blocked. A fresh store open retries the
        // journal recovery and restores the exact pre-restore file set.
        assert!(matches!(
            store.recover_with_hook(|point| {
                if point == InstallCheckpoint::RollbackReplace(3) {
                    Err(std::io::Error::other("injected rollback failure"))
                } else {
                    Ok(())
                }
            }),
            Err(PersistenceError::RecoveryRequired)
        ));
        let resolved = SettingsFile::parse_toml(SETTINGS)
            .unwrap()
            .validate()
            .unwrap()
            .resolve_paths(root.path());
        let reopened = SavedStore::new(root.path(), resolved).expect("store reopens");
        let recovered = reopened.read_saved().expect("journal rolls back on reopen");
        assert_eq!(recovered.settings, before_restore.settings);
        assert_eq!(recovered.server_config, before_restore.server_config);
        assert_eq!(recovered.internal_state, before_restore.internal_state);
        assert_eq!(recovered.vault, before_restore.vault);

        let pre_restore = app
            .list_backups()
            .expect("backups list after interrupted restore")
            .into_iter()
            .find(|backup| backup.reason == BackupReason::PreRestore)
            .expect("precautionary backup preserved");
        let archived = preview_archive(&store.archives_directory().join(pre_restore.file_name))
            .expect("pre-restore archive remains valid");
        assert_eq!(archived.saved_bytes.settings, before_restore.settings);
        assert_eq!(
            archived.saved_bytes.server_config,
            before_restore.server_config
        );
        assert_eq!(
            archived.saved_bytes.internal_state,
            before_restore.internal_state
        );
        assert_eq!(archived.saved_bytes.vault, before_restore.vault);
        assert_eq!(app.states().applied(), &applied_before);
    }

    #[test]
    fn restore_accepts_changed_non_path_settings_and_rejects_changed_paths() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let app = Application::open(store.clone(), states).expect("application opens");
        let mut saved = store.read_saved().expect("saved bytes");
        saved.settings = String::from_utf8(saved.settings)
            .expect("settings utf8")
            .replace("vpn.example.test:51820", "vpn2.example.test:51821")
            .replace("10.20.0.1\"", "10.20.0.2\"")
            .into_bytes();
        let accepted = create_archive(
            store.archives_directory(),
            BackupReason::Manual,
            HistoricalApplyStatus::Unknown,
            &saved,
        )
        .expect("archive with changed operational settings");
        assert!(
            app.preview_restore(accepted.file_name().unwrap().to_str().unwrap())
                .is_ok()
        );

        saved.settings = String::from_utf8(saved.settings)
            .expect("settings utf8")
            .replace("server.conf", "elsewhere.conf")
            .into_bytes();
        let rejected = create_archive(
            store.archives_directory(),
            BackupReason::Manual,
            HistoricalApplyStatus::Unknown,
            &saved,
        )
        .expect("archive with incompatible path");
        assert!(matches!(
            app.preview_restore(rejected.file_name().unwrap().to_str().unwrap()),
            Err(super::AppError::Persistence(_))
        ));
    }

    #[test]
    fn stale_restore_preview_is_rejected_before_backup_and_keeps_the_draft() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, key, _) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states).expect("application opens");
        let saved = store.read_saved().expect("saved bytes");
        let selected = create_archive(
            store.archives_directory(),
            BackupReason::Manual,
            HistoricalApplyStatus::Unknown,
            &saved,
        )
        .expect("restore archive");
        let preview = app
            .preview_restore(selected.file_name().unwrap().to_str().unwrap())
            .expect("preview is prepared");

        app.rename_client(key, "committed after preview")
            .expect("stage new saved generation");
        app.commit().expect("save new generation");
        app.rename_client(key, "draft retained after stale preview")
            .expect("stage follow-up draft");
        let backup_count = app.list_backups().expect("list backups").len();

        assert!(matches!(
            app.confirm_restore(preview),
            Err(AppError::SavedGenerationChanged)
        ));
        assert_eq!(
            app.list_backups().expect("no precautionary backup").len(),
            backup_count
        );
        assert_eq!(
            app.states()
                .draft()
                .get(&key)
                .expect("draft survives")
                .alias,
            "draft retained after stale preview"
        );
        assert_eq!(
            store
                .read_saved()
                .expect("current generation remains installed")
                .server_config,
            app.saved_bytes().server_config
        );
    }

    #[test]
    fn restore_retains_removed_unprojectable_exact_hosts_through_reopen_and_allocation() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let original = store.read_saved().expect("initial saved bytes");
        let selected = create_archive(
            store.archives_directory(),
            BackupReason::Manual,
            HistoricalApplyStatus::Unknown,
            &original,
        )
        .expect("archive without unsupported peers");

        let broad_key = WireGuardPrivateKey::generate()
            .expect("synthetic broad-route peer key")
            .public_key();
        let pending_key = WireGuardPrivateKey::generate()
            .expect("synthetic exact-route peer key")
            .public_key();
        let mut current = clone_saved(&original);
        current.server_config.extend_from_slice(
            format!(
                "\n[Peer]\nPublicKey = {broad_key}\nAllowedIPs = 10.20.0.77/32, 10.20.0.0/24, fd20::77/128\n\n[Peer]\nPublicKey = {pending_key}\nAllowedIPs = 10.20.0.79/32, fd20::79/128\n"
            )
            .as_bytes(),
        );
        store
            .install(&current, BackupComplete(()))
            .expect("install synthetic current generation");
        let mut app = Application::open(store.clone(), states).expect("open with peer routes");

        // Missing managed metadata makes this peer unprojectable. Deleting it
        // stages its exact addresses without requiring a client snapshot.
        assert!(
            !app.delete_client(pending_key)
                .expect("stage exact-host deletion")
        );
        let preview = app
            .preview_restore(selected.file_name().unwrap().to_str().unwrap())
            .expect("preview combines current and pending reservations");
        app.confirm_restore(preview).expect("restore succeeds");

        let reopened = Application::open_from_saved_store(store.clone())
            .expect("reservations survive a fresh application session");
        let reserved = reopened
            .states()
            .reserved_addresses()
            .iter()
            .copied()
            .collect::<Vec<_>>();
        for address in ["10.20.0.77", "fd20::77", "10.20.0.79", "fd20::79"] {
            assert!(reserved.contains(&address.parse().unwrap()), "{address}");
        }
        assert!(
            !reserved.contains(&"10.20.0.1".parse().unwrap()),
            "broad subnet routes must not be expanded into guessed reservations"
        );

        assert_eq!(
            allocate_ipv4(
                "10.20.0.77/32".parse().unwrap(),
                &AddressAvailability {
                    server: &[],
                    occupied: &[],
                    reserved: &reserved,
                },
            ),
            Err(DomainError::AddressExhausted(AddressFamily::Ipv4))
        );
        assert_eq!(
            allocate_ipv6(
                "fd20::77/128".parse().unwrap(),
                &AddressAvailability {
                    server: &[],
                    occupied: &[],
                    reserved: &reserved,
                },
            ),
            Err(DomainError::AddressExhausted(AddressFamily::Ipv6))
        );
    }

    #[test]
    fn restore_does_not_reserve_unprojectable_exact_hosts_owned_by_restored_document() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, _, _, _) = setup(root.path(), false);
        let mut current = store.read_saved().expect("initial saved bytes");
        let retained_key = WireGuardPrivateKey::generate()
            .expect("synthetic retained-peer key")
            .public_key();
        let deleted_key = WireGuardPrivateKey::generate()
            .expect("synthetic pending-deletion key")
            .public_key();
        current.server_config.extend_from_slice(
            format!(
                "\n[Peer]\nPublicKey = {retained_key}\nAllowedIPs = 10.20.0.77/32, fd20::77/128\n\n[Peer]\nPublicKey = {deleted_key}\nAllowedIPs = 10.20.0.79/32, fd20::79/128\n"
            )
            .as_bytes(),
        );
        current.internal_state = Some(
            PersistedState::new(["10.20.0.88".to_owned()], None)
                .expect("synthetic archived reservation")
                .to_toml()
                .expect("archived reservation serializes"),
        );
        store
            .install(&current, BackupComplete(()))
            .expect("install synthetic unprojectable peers");
        let archive = create_archive(
            store.archives_directory(),
            BackupReason::Manual,
            HistoricalApplyStatus::Unknown,
            &current,
        )
        .expect("archive restored peer routes");
        let mut app = Application::open_from_saved_store(store.clone())
            .expect("application opens with unprojectable peers");

        assert!(
            !app.delete_client(deleted_key)
                .expect("stage pending peer deletion")
        );
        assert_eq!(
            app.states()
                .address_reservations()
                .pending_host_routes()
                .count(),
            2
        );
        let preview = app
            .preview_restore(archive.file_name().unwrap().to_str().unwrap())
            .expect("preview archive restoring exact routes");
        app.confirm_restore(preview).expect("restore succeeds");

        assert_eq!(app.states().reserved_addresses().len(), 1);
        assert!(
            app.states()
                .reserved_addresses()
                .contains(&"10.20.0.88".parse().expect("archived reservation"))
        );
        assert!(
            app.states()
                .address_reservations()
                .pending_host_routes()
                .next()
                .is_none()
        );
        let restored_state = PersistedState::from_toml(
            app.saved_bytes()
                .internal_state
                .as_deref()
                .expect("archived reservation remains persisted"),
        )
        .expect("restored state remains valid");
        assert_eq!(restored_state.reserved_addresses, ["10.20.0.88"]);
    }

    #[test]
    fn restoring_absent_optional_components_removes_installed_vault_and_state() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states).expect("application opens");
        let initial = store.read_saved().expect("initial bytes");
        let selected = create_archive(
            store.archives_directory(),
            BackupReason::Manual,
            HistoricalApplyStatus::Unknown,
            &initial,
        )
        .expect("initial-state archive");
        app.prepare_initial_vault(VaultBundle::create("synthetic password").expect("vault"))
            .expect("vault staged");
        app.commit().expect("vault installed");
        assert!(store.read_saved().expect("installed").vault.is_some());
        let mut current = store.read_saved().expect("current saved bytes");
        let removed_key = WireGuardPrivateKey::generate()
            .expect("synthetic removed-peer key")
            .public_key();
        current.server_config.extend_from_slice(
            format!(
                "\n[Peer]\nPublicKey = {removed_key}\nAllowedIPs = 10.20.0.9/32, fd20::9/128\n"
            )
            .as_bytes(),
        );
        store
            .install(&current, BackupComplete(()))
            .expect("install current peer removed by archive");

        let preview = app
            .preview_restore(selected.file_name().unwrap().to_str().unwrap())
            .expect("preview initial state");
        app.confirm_restore(preview).expect("restore initial state");
        let restored = store.read_saved().expect("restored state");
        assert!(restored.vault.is_none());
        let state = PersistedState::from_toml(
            restored
                .internal_state
                .as_deref()
                .expect("removed current routes are retained"),
        )
        .expect("restored reservation state parses");
        assert!(state.reserved_addresses.contains(&"10.20.0.9".to_owned()));
        assert!(state.reserved_addresses.contains(&"fd20::9".to_owned()));
        assert!(app.vault().is_none());
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
    }

    #[test]
    fn failed_pre_restore_backup_preserves_installed_files_and_draft() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, key, _) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states).expect("application opens");
        let saved = store.read_saved().expect("saved");
        let selected = create_archive(
            store.archives_directory(),
            BackupReason::Manual,
            HistoricalApplyStatus::Unknown,
            &saved,
        )
        .expect("archive");
        app.rename_client(key, "draft retained")
            .expect("draft rename");
        let installed = store.read_saved().expect("installed state");
        let preview = app
            .preview_restore(selected.file_name().unwrap().to_str().unwrap())
            .expect("preview");

        let archive_dir = store.archives_directory();
        fs::remove_dir_all(archive_dir).expect("remove synthetic archive directory");
        fs::write(archive_dir, b"cannot create a backup here").expect("replace with file");
        assert!(app.confirm_restore(preview).is_err());
        assert_eq!(
            store.read_saved().expect("files preserved").server_config,
            installed.server_config
        );
        assert_eq!(
            app.states().draft().get(&key).expect("draft client").alias,
            "draft retained"
        );
    }

    #[test]
    fn manual_and_pre_restart_backups_are_listed_without_runtime_calls() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let mut app = Application::open(store, states).expect("application opens");
        app.create_manual_backup().expect("manual backup");
        app.create_pre_restart_backup().expect("pre-restart backup");
        let listed = app.list_backups().expect("backup listing");
        assert_eq!(listed.len(), 2);
        assert!(
            listed
                .iter()
                .any(|item| item.reason == BackupReason::Manual)
        );
        assert!(
            listed
                .iter()
                .any(|item| item.reason == BackupReason::PreRestart)
        );
        assert!(
            listed
                .iter()
                .all(|item| item.historical_apply == HistoricalApplyStatus::Unknown)
        );
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
    }

    #[test]
    fn restart_cancel_preserves_draft_and_never_calls_adapters() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, key) = prepare_restartable(root.path());
        app.rename_client(key, "pending draft")
            .expect("stage draft alias");
        let preview = app.preview_restart().expect("preview saved generation");
        let called = std::cell::Cell::new(false);
        let report = app.restart_with_adapters(
            preview,
            RestartChoice::Cancel,
            |_, _| {
                called.set(true);
                RestartExecution {
                    outcome: RestartOutcome::Succeeded,
                    submitted: true,
                    phase: crate::service::RestartPhase::WaitForJob,
                }
            },
            |_, _| {
                called.set(true);
                Err(TransportError::Transport)
            },
            |_, _, _| {
                called.set(true);
                Ok(())
            },
        );
        assert_eq!(report.stage, RestartStage::Cancelled);
        assert!(!called.get());
        assert_eq!(
            app.states().draft().get(&key).unwrap().alias,
            "pending draft"
        );
    }

    #[test]
    fn restart_backup_failure_preserves_draft_and_submits_no_job() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, key) = prepare_restartable(root.path());
        app.rename_client(key, "pending draft")
            .expect("stage draft alias");
        let preview = app.preview_restart().expect("preview saved generation");
        let archives = root.path().join("Backup/archives");
        fs::remove_dir_all(&archives).expect("remove archive directory");
        fs::write(&archives, b"synthetic archive blocker").expect("install archive blocker");
        let submitted = std::cell::Cell::new(false);
        let report = app.restart_with_adapters(
            preview,
            RestartChoice::DiscardDraftAndRestart,
            |_, _| {
                submitted.set(true);
                RestartExecution {
                    outcome: RestartOutcome::Succeeded,
                    submitted: true,
                    phase: crate::service::RestartPhase::WaitForJob,
                }
            },
            |_, _| Err(TransportError::Transport),
            |_, _, _| Ok(()),
        );
        assert_eq!(report.stage, RestartStage::Backup);
        assert_eq!(report.failure, Some(RestartFailureKind::BackupFailed));
        assert!(!report.restart_submitted);
        assert!(!submitted.get());
        assert_eq!(
            app.states().draft().get(&key).unwrap().alias,
            "pending draft"
        );
    }

    #[test]
    fn confirmed_restart_orders_backup_job_read_and_durable_publication() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, key) = prepare_restartable(root.path());
        app.rename_client(key, "discard me")
            .expect("stage draft alias");
        let preview = app.preview_restart().expect("preview saved generation");
        let observation = observed_runtime(&app);
        let archives = root.path().join("Backup/archives");
        let events = std::cell::RefCell::new(Vec::new());
        let report = app.restart_with_adapters(
            preview,
            RestartChoice::DiscardDraftAndRestart,
            |unit, _| {
                assert_eq!(unit, "wg-quick@wg0.service");
                assert!(
                    crate::backup::list_archives(&archives)
                        .expect("archive listing")
                        .iter()
                        .any(|archive| archive.reason == BackupReason::PreRestart)
                );
                events.borrow_mut().push("service");
                RestartExecution {
                    outcome: RestartOutcome::Succeeded,
                    submitted: true,
                    phase: crate::service::RestartPhase::WaitForJob,
                }
            },
            |interface, remaining| {
                assert_eq!(interface, "wg0");
                assert!(!remaining.is_zero());
                events.borrow_mut().push("runtime");
                Ok(observation)
            },
            |store, saved, backup| {
                events.borrow_mut().push("persist");
                store.install(saved, backup)
            },
        );
        assert_eq!(report.stage, RestartStage::Complete, "{report:?}");
        assert!(report.backup_path.is_some());
        assert!(report.restart_submitted);
        assert_eq!(*events.borrow(), vec!["service", "runtime", "persist"]);
        assert_eq!(app.states().applied(), &ApplyStatus::Verified);
        assert_eq!(
            app.states().draft().get(&key).unwrap().alias,
            "restart fixture"
        );
    }

    #[test]
    fn restart_verifies_metadata_free_legacy_routes_without_partial_applied_snapshot() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, _) = prepare_restartable(root.path());
        let deleted_key = WireGuardPrivateKey::generate()
            .expect("synthetic deleted-client key")
            .public_key();
        app.add_client(
            Client::new(
                deleted_key,
                "deleted reservation fixture",
                ClientAddresses {
                    ipv4: "10.20.0.4".parse().expect("synthetic IPv4"),
                    ipv6: Some("fd20::4".parse().expect("synthetic IPv6")),
                },
            )
            .expect("synthetic managed client"),
            None,
        )
        .expect("stage managed client");
        app.commit().expect("save second managed client");
        app.delete_client(deleted_key)
            .expect("delete managed peer in draft");
        app.commit()
            .expect("save deletion and reserve its addresses");
        let mut saved = clone_saved(app.saved_bytes());
        saved.server_config.extend_from_slice(
            format!(
                "\n[Peer]\nPublicKey = {}\nAllowedIPs = 192.0.2.0/24\n\n[Peer]\nPublicKey = {}\nAllowedIPs = 10.20.0.99/32\n",
                PublicKey::from_bytes([19; 32]),
                PublicKey::from_bytes([20; 32]),
            )
            .as_bytes(),
        );
        app.store
            .install(&saved, BackupComplete(()))
            .expect("install synthetic legacy saved generation");
        let mut app = Application::open_from_saved_store(app.store.clone())
            .expect("open metadata-free legacy peers");
        assert!(!app.states().reserved_addresses().is_empty());
        let original_config = app.saved_bytes().server_config.clone();
        let preview = app
            .preview_restart()
            .expect("valid legacy peers are eligible");
        let observation = observed_runtime(&app);
        let report = app.restart_with_adapters(
            preview,
            RestartChoice::RestartSavedState,
            |unit, _| {
                assert_eq!(unit, "wg-quick@wg0.service");
                RestartExecution {
                    outcome: RestartOutcome::Succeeded,
                    submitted: true,
                    phase: crate::service::RestartPhase::WaitForJob,
                }
            },
            |_, _| Ok(observation),
            |store, saved, backup| store.install(saved, backup),
        );

        assert_eq!(report.stage, RestartStage::Complete);
        assert_eq!(app.states().applied(), &ApplyStatus::Verified);
        assert!(app.states().applied_snapshot().is_none());
        assert!(app.states().reserved_addresses().is_empty());
        assert_eq!(app.saved_bytes().server_config, original_config);
        assert!(app.saved_generation_is_verified_applied(app.saved_bytes(), app.document()));
        let mut different_generation = clone_saved(app.saved_bytes());
        different_generation.settings.push(b'\n');
        assert!(!app.saved_generation_is_verified_applied(&different_generation, app.document()));
        let historical_apply = app.historical_apply.clone();
        let reopened = Application::open_from_saved_store(app.store.clone())
            .expect("reopen historically verified saved state");
        assert_eq!(reopened.historical_apply, historical_apply);
        assert_eq!(reopened.states().applied(), &ApplyStatus::Unknown);
        assert!(reopened.states().applied_snapshot().is_none());
        assert!(reopened.states().reserved_addresses().is_empty());
        assert!(
            !reopened
                .saved_generation_is_verified_applied(reopened.saved_bytes(), reopened.document())
        );
    }

    #[test]
    fn unsafe_saved_peer_diagnostics_block_preview_before_backup_with_safe_location() {
        let root = tempfile::tempdir().expect("temp directory");
        let (app, _) = prepare_restartable(root.path());
        let key = PublicKey::from_bytes([21; 32]);
        let mut saved = clone_saved(app.saved_bytes());
        saved.server_config.extend_from_slice(
            format!(
                "\n[Peer]\nPublicKey = {key}\nPresharedKey = synthetic-peer-secret\nAllowedIPs = malformed-route\n"
            )
            .as_bytes(),
        );
        app.store
            .install(&saved, BackupComplete(()))
            .expect("install malformed synthetic peer");
        let app = Application::open_from_saved_store(app.store.clone())
            .expect("open malformed peer for diagnostics");
        let backup_count = app.list_backups().expect("list existing archives").len();

        let error = match app.preview_restart() {
            Ok(_) => panic!("unsafe peer must block preview"),
            Err(error) => error,
        };
        let AppError::UnsafeSavedPeers(diagnostics) = error else {
            panic!("expected actionable unsafe peer diagnostics");
        };
        assert!(diagnostics.iter().any(|diagnostic| {
            diagnostic.identity == Some(key)
                && diagnostic.section_line.is_some()
                && diagnostic.reason == "peer has a malformed AllowedIPs item"
        }));
        let rendered = format!("{diagnostics:?}");
        assert!(!rendered.contains("synthetic-peer-secret"));
        assert!(!rendered.contains("malformed-route"));
        assert_eq!(
            app.list_backups().expect("backup listing").len(),
            backup_count,
            "unsafe preview must not create a restart archive"
        );
    }

    #[test]
    fn incomplete_legacy_runtime_match_keeps_deleted_addresses_reserved() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, _) = prepare_restartable(root.path());
        let deleted_key = WireGuardPrivateKey::generate()
            .expect("synthetic deleted-client key")
            .public_key();
        app.add_client(
            Client::new(
                deleted_key,
                "deleted reservation fixture",
                ClientAddresses {
                    ipv4: "10.20.0.4".parse().expect("synthetic IPv4"),
                    ipv6: Some("fd20::4".parse().expect("synthetic IPv6")),
                },
            )
            .expect("synthetic managed client"),
            None,
        )
        .expect("stage managed client");
        app.commit().expect("save second managed client");
        app.delete_client(deleted_key)
            .expect("delete managed peer in draft");
        app.commit()
            .expect("save deletion and reserve its addresses");
        let reserved_before = app.states().reserved_addresses().clone();
        let mut saved = clone_saved(app.saved_bytes());
        let legacy_key = PublicKey::from_bytes([22; 32]);
        saved.server_config.extend_from_slice(
            format!("\n[Peer]\nPublicKey = {legacy_key}\nAllowedIPs = 10.20.0.99/32\n").as_bytes(),
        );
        app.store
            .install(&saved, BackupComplete(()))
            .expect("install synthetic legacy peer");
        let mut app =
            Application::open_from_saved_store(app.store.clone()).expect("reopen with legacy peer");
        let preview = app.preview_restart().expect("legacy peer preview succeeds");
        let mut incomplete = observed_runtime(&app);
        let InterfaceObservation::Present { peers, .. } = &mut incomplete.interface else {
            panic!("fixture interface is present");
        };
        peers.peers.remove(&legacy_key);

        let report = app.restart_with_adapters(
            preview,
            RestartChoice::RestartSavedState,
            |_, _| RestartExecution {
                outcome: RestartOutcome::Succeeded,
                submitted: true,
                phase: crate::service::RestartPhase::WaitForJob,
            },
            |_, _| Ok(incomplete),
            |store, saved, backup| store.install(saved, backup),
        );

        assert_eq!(report.stage, RestartStage::Verification);
        assert_eq!(report.failure, Some(RestartFailureKind::RuntimeMismatch));
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        assert_eq!(app.states().reserved_addresses(), &reserved_before);
        let reopened = Application::open_from_saved_store(app.store.clone())
            .expect("failed verification leaves saved reservations durable");
        assert_eq!(reopened.states().reserved_addresses(), &reserved_before);
        assert_eq!(reopened.states().applied(), &ApplyStatus::Unknown);
    }

    #[test]
    fn ambiguous_identity_and_malformed_structure_block_restart_preview() {
        for malformed in [false, true] {
            let root = tempfile::tempdir().expect("temp directory");
            let (app, managed_identity) = prepare_restartable(root.path());
            let mut saved = clone_saved(app.saved_bytes());
            if malformed {
                saved.server_config.extend_from_slice(
                    b"\n[Peer\nPublicKey = AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=\n",
                );
            } else {
                saved.server_config.extend_from_slice(
                    format!(
                        "\n[Peer]\nPublicKey = {managed_identity}\nAllowedIPs = 10.20.0.8/32\n"
                    )
                    .as_bytes(),
                );
            }
            app.store
                .install(&saved, BackupComplete(()))
                .expect("install unsafe synthetic saved bytes");
            let app = Application::open_from_saved_store(app.store.clone())
                .expect("open unsafe saved bytes for preview");
            let error = match app.preview_restart() {
                Ok(_) => panic!("unsafe saved bytes must block restart preview"),
                Err(error) => error,
            };
            let AppError::UnsafeSavedPeers(diagnostics) = error else {
                panic!("expected safe structured diagnostics");
            };
            let expected_reason = if malformed {
                "malformed section header"
            } else {
                "public key is used by multiple peer sections"
            };
            assert!(diagnostics.iter().any(|diagnostic| {
                diagnostic.reason == expected_reason && diagnostic.section_line.is_some()
            }));
        }
    }

    #[test]
    fn service_timeout_reports_submission_and_may_still_complete() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, _) = prepare_restartable(root.path());
        let preview = app.preview_restart().expect("preview saved generation");
        let runtime_called = std::cell::Cell::new(false);
        let report = app.restart_with_adapters(
            preview,
            RestartChoice::RestartSavedState,
            |_, _| RestartExecution {
                outcome: RestartOutcome::Failed(RestartFailure::WaitTimedOutMayStillComplete),
                submitted: true,
                phase: crate::service::RestartPhase::WaitForJob,
            },
            |_, _| {
                runtime_called.set(true);
                Err(TransportError::Transport)
            },
            |_, _, _| Ok(()),
        );
        assert_eq!(report.stage, RestartStage::Service);
        assert!(report.restart_submitted);
        assert!(report.restart_may_still_complete);
        assert!(report.manual_recovery_required);
        assert!(!runtime_called.get());
    }

    #[test]
    fn shared_deadline_expired_after_successful_job_stops_before_runtime_read() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, key) = prepare_restartable(root.path());
        app.delete_client(key).expect("delete saved peer in draft");
        app.commit().expect("save deletion and reservation");
        let preview = app.preview_restart().expect("preview saved generation");
        let started_at = Instant::now();
        let clock_values = [started_at, started_at + Duration::from_secs(30)];
        let clock_index = std::cell::Cell::new(0);
        let runtime_called = std::cell::Cell::new(false);

        let report = app.restart_with_adapters_and_clock(
            preview,
            RestartChoice::RestartSavedState,
            |_, deadline| {
                assert_eq!(deadline.started_at(), started_at);
                assert_eq!(deadline.timeout(), Duration::from_secs(30));
                RestartExecution {
                    outcome: RestartOutcome::Succeeded,
                    submitted: true,
                    phase: crate::service::RestartPhase::WaitForJob,
                }
            },
            |_, _| {
                runtime_called.set(true);
                Err(TransportError::Transport)
            },
            |store, saved, backup| store.install(saved, backup),
            || {
                let index = clock_index.get();
                clock_index.set(index + 1);
                clock_values[index]
            },
        );

        assert_eq!(report.stage, RestartStage::RuntimeRead);
        assert_eq!(report.failure, Some(RestartFailureKind::RuntimeTimeout));
        assert!(report.backup_path.is_some());
        assert!(report.restart_submitted);
        assert!(!report.restart_may_still_complete);
        assert!(report.manual_recovery_required);
        assert!(!runtime_called.get());
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        assert!(!app.states().reserved_addresses().is_empty());
    }

    #[test]
    fn shared_deadline_expired_after_runtime_read_reports_timeout_before_comparison() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, key) = prepare_restartable(root.path());
        app.delete_client(key).expect("delete saved peer in draft");
        app.commit().expect("save deletion and reservation");
        let preview = app.preview_restart().expect("preview saved generation");
        let started_at = Instant::now();
        let clock_values = [started_at, started_at, started_at + Duration::from_secs(30)];
        let clock_index = std::cell::Cell::new(0);
        let install_called = std::cell::Cell::new(false);
        let observation = observed_runtime(&app);

        let report = app.restart_with_adapters_and_clock(
            preview,
            RestartChoice::RestartSavedState,
            |_, deadline| {
                assert_eq!(deadline.started_at(), started_at);
                assert_eq!(deadline.timeout(), Duration::from_secs(30));
                RestartExecution {
                    outcome: RestartOutcome::Succeeded,
                    submitted: true,
                    phase: crate::service::RestartPhase::WaitForJob,
                }
            },
            |_, remaining| {
                assert_eq!(remaining, Duration::from_secs(30));
                Ok(observation)
            },
            |store, saved, backup| {
                install_called.set(true);
                store.install(saved, backup)
            },
            || {
                let index = clock_index.get();
                clock_index.set(index + 1);
                clock_values[index]
            },
        );

        assert_eq!(report.stage, RestartStage::Verification);
        assert_eq!(report.failure, Some(RestartFailureKind::RuntimeTimeout));
        assert!(report.backup_path.is_some());
        assert!(report.restart_submitted);
        assert!(!report.restart_may_still_complete);
        assert!(report.manual_recovery_required);
        assert!(!install_called.get());
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        assert!(!app.states().reserved_addresses().is_empty());
    }

    #[test]
    fn runtime_transport_failures_remain_distinct_in_public_reports() {
        let cases = [
            (
                TransportError::NoDevice,
                RestartFailureKind::RuntimeNoDevice,
            ),
            (
                TransportError::PermissionDenied,
                RestartFailureKind::RuntimePermissionDenied,
            ),
            (
                TransportError::Malformed,
                RestartFailureKind::RuntimeMalformed,
            ),
            (
                TransportError::Transport,
                RestartFailureKind::RuntimeTransport,
            ),
            (TransportError::Timeout, RestartFailureKind::RuntimeTimeout),
            (
                TransportError::LimitExceeded,
                RestartFailureKind::RuntimeLimitExceeded,
            ),
        ];

        for (error, expected) in cases {
            let root = tempfile::tempdir().expect("temp directory");
            let (mut app, _) = prepare_restartable(root.path());
            let preview = app.preview_restart().expect("preview saved generation");
            let install_called = std::cell::Cell::new(false);
            let report = app.restart_with_adapters(
                preview,
                RestartChoice::RestartSavedState,
                |_, _| RestartExecution {
                    outcome: RestartOutcome::Succeeded,
                    submitted: true,
                    phase: crate::service::RestartPhase::WaitForJob,
                },
                |_, _| Err(error),
                |store, saved, backup| {
                    install_called.set(true);
                    store.install(saved, backup)
                },
            );

            assert_eq!(report.stage, RestartStage::RuntimeRead);
            assert_eq!(report.failure, Some(expected));
            assert!(report.restart_submitted);
            assert!(!report.restart_may_still_complete);
            assert!(report.manual_recovery_required);
            assert!(!install_called.get());
            assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        }
    }

    #[test]
    fn submitted_terminal_job_failures_cannot_still_complete() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, _) = prepare_restartable(root.path());

        for failure in [
            RestartFailure::JobFailed,
            RestartFailure::JobDependency,
            RestartFailure::JobTimedOut,
            RestartFailure::JobCanceled,
            RestartFailure::JobSkipped,
            RestartFailure::JobResultUnknown,
        ] {
            let preview = app.preview_restart().expect("preview saved generation");
            let report = app.restart_with_adapters(
                preview,
                RestartChoice::RestartSavedState,
                |_, _| RestartExecution {
                    outcome: RestartOutcome::Failed(failure),
                    submitted: true,
                    phase: crate::service::RestartPhase::WaitForJob,
                },
                |_, _| unreachable!("terminal service failure must stop before runtime read"),
                |_, _, _| unreachable!("terminal service failure must stop before persistence"),
            );

            assert_eq!(report.stage, RestartStage::Service);
            assert!(report.restart_submitted);
            assert!(!report.restart_may_still_complete);
            assert!(report.manual_recovery_required);
        }
    }

    #[test]
    fn application_report_preserves_every_service_failure_and_operation_phase() {
        use crate::service::RestartPhase;

        let cases = [
            (RestartFailure::JobFailed, RestartPhase::WaitForJob, true),
            (
                RestartFailure::JobDependency,
                RestartPhase::WaitForJob,
                true,
            ),
            (RestartFailure::JobTimedOut, RestartPhase::WaitForJob, true),
            (RestartFailure::JobCanceled, RestartPhase::WaitForJob, true),
            (RestartFailure::JobSkipped, RestartPhase::WaitForJob, true),
            (
                RestartFailure::JobResultUnknown,
                RestartPhase::WaitForJob,
                true,
            ),
            (
                RestartFailure::BusDisconnected,
                RestartPhase::Connect,
                false,
            ),
            (
                RestartFailure::ManagerOwnerChanged,
                RestartPhase::WaitForJob,
                true,
            ),
            (
                RestartFailure::ManagerOwnerChanged,
                RestartPhase::RequestRestart,
                true,
            ),
            (
                RestartFailure::SubscriptionFailed,
                RestartPhase::Subscribe,
                false,
            ),
            (
                RestartFailure::UnitResolutionFailed,
                RestartPhase::ResolveUnit,
                false,
            ),
            (
                RestartFailure::PermissionDenied,
                RestartPhase::ResolveUnit,
                false,
            ),
            (
                RestartFailure::RequestFailed,
                RestartPhase::RequestRestart,
                false,
            ),
            (
                RestartFailure::WaitTimedOutMayStillComplete,
                RestartPhase::WaitForJob,
                true,
            ),
            (
                RestartFailure::EarlyEventBufferFull,
                RestartPhase::WaitForJob,
                true,
            ),
            (
                RestartFailure::InvalidJobPath,
                RestartPhase::WaitForJob,
                true,
            ),
        ];

        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, _) = prepare_restartable(root.path());
        for (failure, phase, submitted) in cases {
            let preview = app.preview_restart().expect("preview saved generation");
            let report = app.restart_with_adapters(
                preview,
                RestartChoice::RestartSavedState,
                |_, _| RestartExecution {
                    outcome: RestartOutcome::Failed(failure),
                    submitted,
                    phase,
                },
                |_, _| unreachable!("service failure must stop before runtime read"),
                |_, _, _| unreachable!("service failure must stop before persistence"),
            );
            assert_eq!(report.failure, Some(RestartFailureKind::ServiceFailed));
            assert_eq!(report.service_failure, Some(failure));
            assert_eq!(report.service_phase, Some(phase));
            assert_eq!(report.systemd_unit.as_deref(), Some("wg-quick@wg0.service"));
            assert_eq!(report.restart_submitted, submitted);
            if failure == RestartFailure::ManagerOwnerChanged
                && phase == RestartPhase::RequestRestart
            {
                assert!(report.restart_may_still_complete);
                assert!(report.manual_recovery_required);
            }
            assert_eq!(
                report.restart_may_still_complete,
                submitted
                    && !matches!(
                        failure,
                        RestartFailure::JobFailed
                            | RestartFailure::JobDependency
                            | RestartFailure::JobTimedOut
                            | RestartFailure::JobCanceled
                            | RestartFailure::JobSkipped
                            | RestartFailure::JobResultUnknown
                    )
            );
            assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        }
    }

    #[test]
    fn restart_mismatch_and_post_restart_write_failure_never_release_addresses() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, key) = prepare_restartable(root.path());
        app.delete_client(key).expect("delete saved peer in draft");
        app.commit().expect("save deletion and reservation");
        assert!(!app.states().reserved_addresses().is_empty());
        let preview = app.preview_restart().expect("preview empty saved peer set");
        let mismatch = app.restart_with_adapters(
            preview,
            RestartChoice::RestartSavedState,
            |_, _| RestartExecution {
                outcome: RestartOutcome::Succeeded,
                submitted: true,
                phase: crate::service::RestartPhase::WaitForJob,
            },
            |_, _| {
                Ok(RuntimeObservation {
                    observed_at: None,
                    interface: InterfaceObservation::Missing,
                })
            },
            |store, saved, backup| store.install(saved, backup),
        );
        assert_eq!(mismatch.stage, RestartStage::Verification);
        assert!(!app.states().reserved_addresses().is_empty());

        let preview = app.preview_restart().expect("preview remains available");
        let observation = observed_runtime(&app);
        let failed_write = app.restart_with_adapters(
            preview,
            RestartChoice::RestartSavedState,
            |_, _| RestartExecution {
                outcome: RestartOutcome::Succeeded,
                submitted: true,
                phase: crate::service::RestartPhase::WaitForJob,
            },
            |_, _| Ok(observation),
            |_, _, _| Err(PersistenceError::RecoveryRequired),
        );
        assert_eq!(failed_write.stage, RestartStage::Persistence);
        assert!(failed_write.manual_recovery_required);
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        assert!(!app.states().reserved_addresses().is_empty());
    }

    #[test]
    fn restart_rejects_unsafe_saveconfig_before_backup_or_submission() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, key) = prepare_restartable(root.path());
        let mut saved = clone_saved(app.saved_bytes());
        let server = String::from_utf8(saved.server_config.clone()).expect("synthetic config");
        saved.server_config = server
            .replace(
                "Address = 10.20.0.1/24",
                "Address = 10.20.0.1/24\nSaveConfig = true",
            )
            .into_bytes();
        app.store
            .install(&saved, BackupComplete(()))
            .expect("install synthetic unsafe generation");
        let reopened_store = app.store.clone();
        let states = app.draft.states.clone();
        app = Application::open(reopened_store, states).expect("reopen fixture");
        app.rename_client(key, "draft")
            .expect("stage a draft for preservation");
        assert!(matches!(
            app.preview_restart(),
            Err(AppError::UnsafeSaveConfig)
        ));
    }

    #[test]
    fn restart_confirmation_rejects_a_generation_changed_after_preview() {
        let root = tempfile::tempdir().expect("temp directory");
        let (mut app, _) = prepare_restartable(root.path());
        let preview = app.preview_restart().expect("preview saved generation");
        let mut externally_replaced = clone_saved(app.saved_bytes());
        let settings =
            String::from_utf8(externally_replaced.settings.clone()).expect("synthetic settings");
        externally_replaced.settings = settings
            .replace("wg-quick@wg0.service", "wg-quick@wg1.service")
            .into_bytes();
        app.store
            .install(&externally_replaced, BackupComplete(()))
            .expect("install changed synthetic generation");
        let called = std::cell::Cell::new(false);
        let report = app.restart_with_adapters(
            preview,
            RestartChoice::RestartSavedState,
            |_, _| {
                called.set(true);
                RestartExecution {
                    outcome: RestartOutcome::Succeeded,
                    submitted: true,
                    phase: crate::service::RestartPhase::WaitForJob,
                }
            },
            |_, _| Err(TransportError::Transport),
            |_, _, _| Ok(()),
        );
        assert_eq!(report.stage, RestartStage::Preparation);
        assert_eq!(
            report.failure,
            Some(RestartFailureKind::InvalidOrStaleSavedGeneration)
        );
        assert!(!called.get());
        assert!(report.backup_path.is_none());
    }

    #[test]
    fn verified_history_persists_across_reopen_without_marking_runtime_applied() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states.clone()).expect("application opens");
        let verified_at = "2026-10-20T08:15:00Z";
        let observed = app.states().saved().clone();
        test_mark_verified(&mut app, observed, verified_at.to_owned())
            .expect("verified generation persists");

        let saved = store.read_saved().expect("verified saved bytes");
        assert_eq!(
            PersistedState::from_toml(saved.internal_state.as_deref().unwrap())
                .unwrap()
                .last_verified_at_utc
                .as_deref(),
            Some(verified_at)
        );
        let reopened = Application::open(store, states).expect("application reopens");
        assert_eq!(
            reopened.historical_apply,
            HistoricalApplyStatus::Verified {
                verified_at_utc: verified_at.to_owned()
            }
        );
        assert_eq!(reopened.states().applied(), &ApplyStatus::Unknown);
    }

    #[test]
    fn open_does_not_treat_caller_seeded_verified_state_as_runtime_evidence() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, seeded, _, _) = setup(root.path(), false);
        assert_eq!(seeded.applied(), &ApplyStatus::Verified);
        let app = Application::open(store, seeded).expect("application opens");

        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        assert!(app.states().applied_snapshot().is_some());
        assert!(!app.saved_generation_is_verified_applied(app.saved_bytes(), app.document()));
    }

    #[test]
    fn failed_verified_history_write_does_not_advance_memory_or_reopen_as_verified() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states.clone()).expect("application opens");
        let before = store.read_saved().expect("original saved bytes");
        let observed = app.states().saved().clone();
        app.create_pre_restart_backup()
            .expect("pre-restart backup completes");
        let id = app.next_restart_attempt;
        app.next_restart_attempt += 1;
        app.active_restart_attempt = Some(id);
        let attempt = super::RestartAttempt {
            id,
            saved: clone_saved(&app.saved),
        };
        let result = app.mark_verified_with_attempt(
            attempt,
            Some(observed),
            "2026-10-20T08:30:00Z".to_owned(),
            |store, saved, _backup| {
                store.install_with_hook(saved, |point| {
                    if point == InstallCheckpoint::Replaced(3) {
                        Err(std::io::Error::other("history-state install interruption"))
                    } else {
                        Ok(())
                    }
                })
            },
        );
        assert!(matches!(
            result,
            Err(AppError::Persistence(PersistenceError::RecoveryRequired))
        ));
        assert_eq!(app.historical_apply, HistoricalApplyStatus::Unknown);
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        assert_eq!(app.saved_bytes().internal_state, before.internal_state);

        let resolved = SettingsFile::parse_toml(SETTINGS)
            .unwrap()
            .validate()
            .unwrap()
            .resolve_paths(root.path());
        let reopened_store = SavedStore::new(root.path(), resolved).expect("store reopens");
        let recovered = reopened_store
            .read_saved()
            .expect("interrupted history write rolls back");
        assert_eq!(recovered.internal_state, before.internal_state);
        let reopened = Application::open(reopened_store, states).expect("application reopens");
        assert_eq!(reopened.historical_apply, HistoricalApplyStatus::Unknown);
        assert_eq!(reopened.states().applied(), &ApplyStatus::Unknown);
    }

    #[test]
    fn precommit_archive_records_verified_installed_generation_and_success_clears_it() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, key, _) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states.clone()).expect("application opens");
        let verified_at = "2026-10-20T09:00:00Z";
        let observed = app.states().saved().clone();
        test_mark_verified(&mut app, observed, verified_at.to_owned())
            .expect("verified generation persists");
        app.rename_client(key, "next saved alias")
            .expect("draft alias");
        let archive = app.commit().expect("commit succeeds");
        let archived = preview_archive(&archive).expect("pre-commit archive is valid");
        assert_eq!(
            archived.historical_apply,
            HistoricalApplyStatus::Verified {
                verified_at_utc: verified_at.to_owned()
            }
        );
        assert_eq!(app.historical_apply, HistoricalApplyStatus::Unknown);
        assert_eq!(
            PersistedState::from_toml(
                store
                    .read_saved()
                    .unwrap()
                    .internal_state
                    .as_deref()
                    .unwrap()
            )
            .unwrap()
            .last_verified_at_utc,
            None
        );
        let reopened = Application::open(store, states).expect("committed state reopens");
        assert_eq!(reopened.historical_apply, HistoricalApplyStatus::Unknown);
        assert_eq!(reopened.states().applied(), &ApplyStatus::Unknown);
    }

    #[test]
    fn failed_commit_retains_verified_history_and_retryable_draft() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, key, _) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states).expect("application opens");
        let verified_at = "2026-10-20T10:00:00Z";
        let observed = app.states().saved().clone();
        test_mark_verified(&mut app, observed, verified_at.to_owned())
            .expect("verified generation persists");
        let before = store.read_saved().expect("verified saved bytes");
        app.rename_client(key, "retryable draft")
            .expect("draft alias");

        let archives = store.archives_directory().to_path_buf();
        fs::remove_dir_all(&archives).expect("remove synthetic archive directory");
        fs::write(&archives, b"block commit backup").expect("install backup blocker");
        assert!(matches!(app.commit(), Err(AppError::Backup(_))));
        let persisted = PersistedState::from_toml(before.internal_state.as_deref().unwrap())
            .expect("prior state parses");
        assert_eq!(persisted.last_verified_at_utc.as_deref(), Some(verified_at));
        assert_eq!(
            app.historical_apply,
            HistoricalApplyStatus::Verified {
                verified_at_utc: verified_at.to_owned()
            }
        );
        assert_eq!(app.saved_bytes().server_config, before.server_config);
        assert_eq!(
            app.states().draft().get(&key).unwrap().alias,
            "retryable draft"
        );
        assert_eq!(app.states().saved().get(&key).unwrap().alias, "legacy-view");
    }

    #[test]
    fn successful_restore_clears_verified_current_history_but_backup_retains_it() {
        let root = tempfile::tempdir().expect("temp directory");
        let (store, states, _, _) = setup(root.path(), false);
        let mut app = Application::open(store.clone(), states.clone()).expect("application opens");
        let selected = app.create_manual_backup().expect("select initial archive");
        let verified_at = "2026-10-20T11:00:00Z";
        let observed = app.states().saved().clone();
        test_mark_verified(&mut app, observed, verified_at.to_owned())
            .expect("verified generation persists");
        let preview = app
            .preview_restore(selected.file_name().unwrap().to_str().unwrap())
            .expect("restore preview validates");
        let pre_restore = app.confirm_restore(preview).expect("restore succeeds");

        assert_eq!(app.historical_apply, HistoricalApplyStatus::Unknown);
        assert_eq!(app.states().applied(), &ApplyStatus::Unknown);
        let archived = preview_archive(&pre_restore).expect("pre-restore backup validates");
        assert_eq!(
            archived.historical_apply,
            HistoricalApplyStatus::Verified {
                verified_at_utc: verified_at.to_owned()
            }
        );
        let restored = store.read_saved().expect("restored saved bytes parse");
        assert!(
            restored.internal_state.is_none(),
            "the selected archive had no state and restored routes need no reservation"
        );
        let restored_document = ConfigDocument::parse(&restored.server_config).unwrap();
        let reopened_states = ClientStates::new(
            snapshot_from_document(&restored_document),
            None,
            ApplyStatus::Unknown,
        )
        .unwrap();
        let reopened = Application::open(store, reopened_states).expect("restored state reopens");
        assert_eq!(reopened.historical_apply, HistoricalApplyStatus::Unknown);
        assert_eq!(reopened.states().applied(), &ApplyStatus::Unknown);
    }
}