use std::sync::Arc;

use super::current_otel_trace_id;
use toolkit_macros::domain_model;
use tracing::{debug, error, warn};
use uuid::Uuid;

use mini_chat_sdk::{
    AuditUsageTokens, LatencyMs, PolicyDecisions, QuotaDecision, TurnAuditEvent,
    TurnAuditEventType, UsageEvent, UsageTokens,
};

use crate::domain::error::DomainError;
use crate::domain::model::audit_envelope::AuditEnvelope;
use crate::domain::model::billing_outcome::{
    BillingDerivation, BillingDerivationInput, BillingOutcome, derive_billing_outcome,
};
use crate::domain::model::finalization::{
    FinalizationInput, FinalizationOutcome, has_known_usage, settlement_path_from_billing,
};
use crate::domain::model::quota::{SettlementInput, SettlementMethod, SettlementOutcome};
use crate::domain::repos::{
    CasTerminalParams, InsertAssistantMessageParams, MessageRepository, OutboxEnqueuer,
    TurnRepository,
};
use crate::domain::service::quota_settler::QuotaSettler;
use crate::infra::db::entity::chat_turn::TurnState;
use crate::infra::llm::Usage;

use crate::domain::ports::MiniChatMetricsPort;
use crate::domain::ports::metric_labels::{period, result as result_label, trigger};

use super::DbProvider;

fn to_db(e: DomainError) -> toolkit_db::DbError {
    toolkit_db::DbError::Other(anyhow::anyhow!(e))
}

/// Service encapsulating the atomic finalization transaction.
///
/// Generic over `TR` and `MR` (repository traits are not dyn-compatible
/// due to `&impl DBRunner` methods). The `QuotaService<QR>` generic is
/// erased via the `QuotaSettler` trait (see D2).
///
/// Created once in `AppServices::new()` and shared with spawned tasks
/// via `Arc<FinalizationService<TR, MR>>`.
#[domain_model]
pub struct FinalizationService<TR: TurnRepository + 'static, MR: MessageRepository + 'static> {
    db: Arc<DbProvider>,
    turn_repo: Arc<TR>,
    message_repo: Arc<MR>,
    quota_settler: Arc<dyn QuotaSettler>,
    outbox_enqueuer: Arc<dyn OutboxEnqueuer>,
    metrics: Arc<dyn MiniChatMetricsPort>,
    summary_config: crate::config::background::ThreadSummaryWorkerConfig,
}

/// Evaluate whether thread summary should be triggered.
///
/// Two conditions (OR):
/// 1. Context assembly already truncated messages (`messages_truncated`) — urgent,
///    the conversation is losing context right now.
/// 2. Context fills `>= threshold%` of budget AND no summary exists yet —
///    proactive trigger before truncation starts.
///
/// When a summary already exists and context isn't truncated, we skip —
/// the existing summary is still effective.
fn should_trigger_summary(
    assembled_context_tokens: u64,
    max_output_tokens_applied: i32,
    context_window: u32,
    compression_threshold_pct: u32,
    messages_truncated: bool,
    has_existing_summary: bool,
) -> bool {
    // Urgent: messages already being dropped
    if messages_truncated {
        return true;
    }
    // Proactive: context filling up, but only if no summary exists yet.
    // If a summary already covers older messages, wait until truncation
    // actually starts before re-summarizing.
    if has_existing_summary {
        return false;
    }
    let estimated_input = i64::try_from(assembled_context_tokens).unwrap_or(i64::MAX);
    let effective_budget = i64::from(context_window) - i64::from(max_output_tokens_applied);
    if effective_budget <= 0 || estimated_input <= 0 {
        return false;
    }
    #[allow(clippy::integer_division)]
    let threshold = effective_budget * i64::from(compression_threshold_pct) / 100;
    estimated_input >= threshold
}

impl<TR: TurnRepository + 'static, MR: MessageRepository + 'static> FinalizationService<TR, MR> {
    pub(crate) fn new(
        db: Arc<DbProvider>,
        turn_repo: Arc<TR>,
        message_repo: Arc<MR>,
        quota_settler: Arc<dyn QuotaSettler>,
        outbox_enqueuer: Arc<dyn OutboxEnqueuer>,
        metrics: Arc<dyn MiniChatMetricsPort>,
        summary_config: crate::config::background::ThreadSummaryWorkerConfig,
    ) -> Self {
        Self {
            db,
            turn_repo,
            message_repo,
            quota_settler,
            outbox_enqueuer,
            metrics,
            summary_config,
        }
    }

    /// Single universal finalization function for all terminal paths.
    ///
    /// Executes CAS guard + billing derivation + quota settlement +
    /// message persistence + outbox enqueue in one atomic DB transaction.
    ///
    /// Returns `FinalizationOutcome { won_cas: false, .. }` if another
    /// finalizer already committed (CAS loser — no-op).
    ///
    /// If message persistence fails on a completed turn, rolls back and
    /// retries as `Failed` with `error_code = "message_persistence_failed"`
    /// (content durability invariant).
    #[allow(clippy::cognitive_complexity)]
    pub(crate) async fn finalize_turn_cas(
        &self,
        input: FinalizationInput,
    ) -> Result<FinalizationOutcome, DomainError> {
        let start = std::time::Instant::now();
        // Capture trace_id before the transaction: the transaction closure runs
        // on the same thread but inside a different async context; capturing here
        // ensures we get the actual request span ID.
        let trace_id = current_otel_trace_id();

        let result = self.try_finalize(&input, trace_id.clone()).await;

        match result {
            Ok(outcome) => {
                // Post-commit side effects (outside transaction).
                if outcome.won_cas {
                    self.outbox_enqueuer.flush();
                }
                if let Some(billing) = outcome.billing_outcome {
                    let ms = start.elapsed().as_secs_f64() * 1000.0;
                    Self::emit_post_commit_side_effects(&input, billing, ms, &*self.metrics);
                }
                Ok(outcome)
            }
            Err(FinalizationError::MessagePersistenceFailed(e)) => {
                if input.terminal_state == TurnState::Completed {
                    // Content durability invariant: downgrade completed → failed.
                    // The transaction rolled back, so the turn is still 'running'.
                    // Retry with Failed state.
                    error!(
                        error = %e,
                        turn_id = %input.turn_id,
                        "message persistence failed, downgrading completed to failed"
                    );
                    let mut retry_input = input;
                    retry_input.terminal_state = TurnState::Failed;
                    retry_input.error_code = Some("message_persistence_failed".to_owned());
                    let retry_outcome = self
                        .try_finalize(&retry_input, trace_id.clone())
                        .await
                        .map_err(|fe| match fe {
                            FinalizationError::Domain(de) => de,
                            FinalizationError::MessagePersistenceFailed(e2) => {
                                DomainError::internal(format!("unexpected retry failure: {e2}"))
                            }
                        })?;
                    if retry_outcome.won_cas {
                        self.outbox_enqueuer.flush();
                    }
                    if let Some(billing) = retry_outcome.billing_outcome {
                        let ms = start.elapsed().as_secs_f64() * 1000.0;
                        Self::emit_post_commit_side_effects(
                            &retry_input,
                            billing,
                            ms,
                            &*self.metrics,
                        );
                    }
                    Ok(retry_outcome)
                } else {
                    // Best-effort path (cancelled turns): log and finalize
                    // without message by clearing accumulated_text (D4).
                    warn!(
                        error = %e,
                        turn_id = %input.turn_id,
                        terminal_state = ?input.terminal_state,
                        "message persistence failed on non-completed turn, \
                         finalizing without message"
                    );
                    let mut retry_input = input;
                    retry_input.accumulated_text = String::new();
                    let retry_outcome =
                        self.try_finalize(&retry_input, trace_id)
                            .await
                            .map_err(|fe| match fe {
                                FinalizationError::Domain(de) => de,
                                FinalizationError::MessagePersistenceFailed(e2) => {
                                    DomainError::internal(format!(
                                        "unexpected message persist on empty text: {e2}"
                                    ))
                                }
                            })?;
                    if retry_outcome.won_cas {
                        self.outbox_enqueuer.flush();
                    }
                    if let Some(billing) = retry_outcome.billing_outcome {
                        let ms = start.elapsed().as_secs_f64() * 1000.0;
                        Self::emit_post_commit_side_effects(
                            &retry_input,
                            billing,
                            ms,
                            &*self.metrics,
                        );
                    }
                    Ok(retry_outcome)
                }
            }
            Err(FinalizationError::Domain(e)) => Err(e),
        }
    }

    /// Core finalization logic inside a transaction.
    #[allow(clippy::too_many_lines)]
    async fn try_finalize(
        &self,
        input: &FinalizationInput,
        trace_id: Option<String>,
    ) -> Result<FinalizationOutcome, FinalizationError> {
        let turn_repo = Arc::clone(&self.turn_repo);
        let message_repo = Arc::clone(&self.message_repo);
        let quota_settler = Arc::clone(&self.quota_settler);
        let outbox_enqueuer = Arc::clone(&self.outbox_enqueuer);
        let metrics = Arc::clone(&self.metrics);
        let summary_config = self.summary_config.clone();
        let input = input.clone();

        let tx_result = self
            .db
            .transaction(|tx| {
                Box::pin(async move {
                    let scope = input.scope.clone();

                    // 1. CAS guard — state transition only.
                    //    assistant_message_id and provider_response_id are set
                    //    AFTER the message INSERT (step 4) to avoid FK violation
                    //    (assistant_message_id REFERENCES messages(id)).
                    let rows = turn_repo
                        .cas_update_state(
                            tx,
                            &scope,
                            CasTerminalParams {
                                turn_id: input.turn_id,
                                state: input.terminal_state.clone(),
                                error_code: input.error_code.clone(),
                                error_detail: input.error_detail.clone(),
                                assistant_message_id: None,
                                provider_response_id: input.provider_response_id.clone(),
                            },
                        )
                        .await
                        .map_err(to_db)?;

                    if rows == 0 {
                        debug!(turn_id = %input.turn_id, "CAS loser: another finalizer won");
                        return Ok(FinalizationOutcome {
                            won_cas: false,
                            billing_outcome: None,
                            settlement_outcome: None,
                        });
                    }

                    // 2. Derive billing outcome (pure function, no DB)
                    let billing = derive_billing_outcome(&BillingDerivationInput {
                        terminal_state: input.terminal_state.clone(),
                        error_code: input.error_code.clone(),
                        has_usage: has_known_usage(input.usage),
                    });

                    // 3. Build SettlementInput and settle quota
                    let settlement_path =
                        settlement_path_from_billing(billing.settlement_method, input.usage);
                    let settlement_input = SettlementInput {
                        tenant_id: input.tenant_id,
                        user_id: input.user_id,
                        effective_model: input.effective_model.clone(),
                        policy_version_applied: input.policy_version_applied,
                        reserve_tokens: input.reserve_tokens,
                        max_output_tokens_applied: input.max_output_tokens_applied,
                        reserved_credits_micro: input.reserved_credits_micro,
                        minimal_generation_floor_applied: input.minimal_generation_floor_applied,
                        settlement_path,
                        period_starts: input.period_starts.clone(),
                        web_search_calls: input.web_search_calls,
                        code_interpreter_calls: input.code_interpreter_calls,
                    };
                    let settlement_outcome = quota_settler
                        .settle_in_tx(tx, &scope, settlement_input)
                        .await
                        .map_err(to_db)?;

                    // 4. Persist assistant message
                    //    Completed: full content, required (retry-as-failed on failure)
                    //    Cancelled with non-empty text: partial content, best-effort
                    let should_persist_message = input.terminal_state == TurnState::Completed
                        || (input.terminal_state == TurnState::Cancelled
                            && !input.accumulated_text.is_empty());

                    if should_persist_message {
                        message_repo
                            .insert_assistant_message(
                                tx,
                                &scope,
                                InsertAssistantMessageParams {
                                    id: input.message_id,
                                    tenant_id: input.tenant_id,
                                    chat_id: input.chat_id,
                                    request_id: input.request_id,
                                    content: input.accumulated_text.clone(),
                                    input_tokens: input.usage.map(|u| u.input_tokens),
                                    output_tokens: input.usage.map(|u| u.output_tokens),
                                    cache_read_input_tokens: input
                                        .usage
                                        .map(|u| u.cache_read_input_tokens),
                                    cache_write_input_tokens: input
                                        .usage
                                        .map(|u| u.cache_write_input_tokens),
                                    reasoning_tokens: input.usage.map(|u| u.reasoning_tokens),
                                    model: Some(input.effective_model.clone()),
                                    provider_response_id: input.provider_response_id.clone(),
                                },
                            )
                            .await
                            .map_err(|e| {
                                // Signal message persistence failure for retry logic.
                                toolkit_db::DbError::Other(anyhow::anyhow!(
                                    "MSG_PERSIST_FAILED:{e}"
                                ))
                            })?;

                        // 4b. Link assistant_message_id on the turn row.
                        //     Done as a separate UPDATE (not in the CAS step) because
                        //     assistant_message_id has a FK to messages(id), so the
                        //     message row must exist first.
                        turn_repo
                            .set_assistant_message_id(tx, &scope, input.turn_id, input.message_id)
                            .await
                            .map_err(to_db)?;
                    }

                    // 5. Enqueue usage outbox event
                    let usage_event = build_usage_event(&input, billing, &settlement_outcome);
                    outbox_enqueuer
                        .enqueue_usage_event(tx, usage_event)
                        .await
                        .map_err(to_db)?;

                    // 6. Enqueue audit outbox event
                    let audit_event = build_turn_audit_envelope(&input, trace_id);
                    outbox_enqueuer
                        .enqueue_audit_event(tx, audit_event)
                        .await
                        .map_err(to_db)?;

                    // 7. Evaluate thread summary trigger (completed turns only).
                    //
                    // Short-circuit: skip the DB read for get_latest() when
                    // the trigger clearly cannot fire (neither truncated nor
                    // above threshold). This avoids an extra SELECT on every
                    // completed turn.
                    let ts_repo =
                        crate::infra::db::repo::thread_summary_repo::ThreadSummaryRepository;
                    let may_trigger = input.terminal_state == TurnState::Completed
                        && summary_config.enabled
                        && (input.messages_truncated
                            || should_trigger_summary(
                                input.assembled_context_tokens,
                                input.max_output_tokens_applied,
                                input.context_window,
                                summary_config.compression_threshold_pct,
                                false, // messages_truncated already checked above
                                false, // optimistic: assume no summary for threshold check
                            ));

                    let (current_summary, summary_triggered) = if may_trigger {
                        let summary = crate::domain::repos::ThreadSummaryRepository::get_latest(
                            &ts_repo,
                            tx,
                            &scope,
                            input.chat_id,
                        )
                        .await
                        .map_err(to_db)?;
                        let triggered = should_trigger_summary(
                            input.assembled_context_tokens,
                            input.max_output_tokens_applied,
                            input.context_window,
                            summary_config.compression_threshold_pct,
                            input.messages_truncated,
                            summary.is_some(),
                        );
                        (summary, triggered)
                    } else {
                        (None, false)
                    };
                    tracing::debug!(
                        terminal_state = ?input.terminal_state,
                        summary_enabled = summary_config.enabled,
                        assembled_context_tokens = input.assembled_context_tokens,
                        messages_truncated = input.messages_truncated,
                        has_existing_summary = current_summary.is_some(),
                        context_window = input.context_window,
                        threshold_pct = summary_config.compression_threshold_pct,
                        summary_triggered,
                        "thread summary trigger decision"
                    );
                    if summary_triggered {
                        let base_frontier = current_summary.as_ref().map(|s| &s.frontier);

                        let frozen_target =
                            crate::domain::repos::MessageRepository::find_latest_message(
                                message_repo.as_ref(),
                                tx,
                                &scope,
                                input.chat_id,
                            )
                            .await
                            .map_err(to_db)?;

                        if let Some(target) = frozen_target {
                            let should_enqueue = match base_frontier {
                                Some(bf) => bf != &target,
                                None => true,
                            };
                            if should_enqueue {
                                let payload = crate::domain::repos::ThreadSummaryTaskPayload {
                                    tenant_id: input.tenant_id,
                                    chat_id: input.chat_id,
                                    system_request_id: Uuid::new_v4(),
                                    system_task_type: "thread_summary_update".to_owned(),
                                    base_frontier_created_at: base_frontier.map(|f| f.created_at),
                                    base_frontier_message_id: base_frontier.map(|f| f.message_id),
                                    frozen_target_created_at: target.created_at,
                                    frozen_target_message_id: target.message_id,
                                };
                                outbox_enqueuer
                                    .enqueue_thread_summary(tx, payload)
                                    .await
                                    .map_err(to_db)?;
                                metrics.record_thread_summary_trigger("scheduled");
                            } else {
                                metrics.record_thread_summary_trigger("not_needed");
                            }
                        }
                    }

                    Ok(FinalizationOutcome {
                        won_cas: true,
                        billing_outcome: Some(billing),
                        settlement_outcome: Some(settlement_outcome),
                    })
                })
            })
            .await;

        match tx_result {
            Ok(outcome) => Ok(outcome),
            Err(e) => {
                // Check if this was a message persistence failure (sentinel).
                let err_str = e.to_string();
                if err_str.contains("MSG_PERSIST_FAILED:") {
                    let inner = err_str
                        .strip_prefix("MSG_PERSIST_FAILED:")
                        .unwrap_or(&err_str);
                    Err(FinalizationError::MessagePersistenceFailed(
                        inner.to_owned(),
                    ))
                } else {
                    Err(FinalizationError::Domain(DomainError::from(e)))
                }
            }
        }
    }

    /// Emit metrics and logs after the transaction commits.
    /// These MUST NOT run inside the transaction.
    fn emit_post_commit_side_effects(
        input: &FinalizationInput,
        billing: BillingDerivation,
        finalization_ms: f64,
        metrics: &dyn MiniChatMetricsPort,
    ) {
        metrics.record_audit_emit(result_label::OK);
        metrics.record_finalization_latency_ms(finalization_ms);
        Self::emit_quota_metrics(input, billing, metrics);
        Self::emit_billing_side_effects(input, billing, metrics);
    }

    fn emit_quota_metrics(
        input: &FinalizationInput,
        billing: BillingDerivation,
        metrics: &dyn MiniChatMetricsPort,
    ) {
        match billing.settlement_method {
            SettlementMethod::Actual => {
                metrics.record_quota_commit(period::DAILY);
                metrics.record_quota_commit(period::MONTHLY);
                if let Some(usage) = input.usage {
                    #[allow(clippy::cast_precision_loss)]
                    let actual = (usage.input_tokens + usage.output_tokens) as f64;
                    metrics.record_quota_actual_tokens(actual);

                    // Overshoot: actual tokens exceeded the reserved estimate.
                    // Overshoot detection: mini_chat_quota_overshoot_total{period}
                    #[allow(clippy::cast_precision_loss)]
                    let reserved = input.reserve_tokens as f64;
                    if actual > reserved {
                        metrics.record_quota_overshoot(period::DAILY);
                        metrics.record_quota_overshoot(period::MONTHLY);
                    }
                }

                if input.code_interpreter_calls > 0 {
                    metrics.record_code_interpreter_calls(
                        &input.effective_model,
                        input.code_interpreter_calls,
                    );
                }
            }
            SettlementMethod::Estimated | SettlementMethod::Released => {
                // No overshoot metric here: overshoot measures actual > reserved,
                // but estimated settlement has no actual usage data to compare.
                // The reserved estimate simply stays as-is until a future
                // reconciliation pass settles it with real numbers.
            }
        }
    }

    fn emit_billing_side_effects(
        input: &FinalizationInput,
        billing: BillingDerivation,
        metrics: &dyn MiniChatMetricsPort,
    ) {
        if billing.unknown_error_code {
            error!(
                error_code = ?input.error_code,
                turn_id = %input.turn_id,
                "CRITICAL: unknown error code in billing derivation"
            );
        }

        if billing.outcome == BillingOutcome::Aborted {
            let abort_trigger = match input.error_code.as_deref() {
                Some("orphan_timeout") => trigger::ORPHAN_TIMEOUT,
                _ if input.terminal_state == TurnState::Cancelled => trigger::CLIENT_DISCONNECT,
                _ => trigger::INTERNAL_ABORT,
            };
            warn!(
                turn_id = %input.turn_id,
                trigger = abort_trigger,
                "stream aborted"
            );
            metrics.record_streams_aborted(abort_trigger);
        }
    }

    /// Finalize an orphan turn within a single database transaction.
    ///
    /// Uses the orphan-specific CAS guard that re-checks all predicates
    /// (`state`=running, `deleted_at` IS NULL, `last_progress_at` <= cutoff).
    /// Reuses billing derivation, quota settlement, and outbox enqueue.
    ///
    /// Returns `Ok(true)` if CAS won (turn finalized), `Ok(false)` if CAS lost.
    pub(crate) async fn finalize_orphan_turn(
        &self,
        input: crate::domain::model::finalization::OrphanFinalizationInput,
        timeout_secs: u64,
    ) -> Result<bool, DomainError> {
        use crate::domain::model::billing_outcome::{
            BillingDerivationInput, derive_billing_outcome,
        };
        use crate::domain::model::quota::SettlementPath;
        use crate::infra::db::entity::quota_usage::PeriodType;
        let start = std::time::Instant::now();
        let turn_repo = Arc::clone(&self.turn_repo);
        let quota_settler = Arc::clone(&self.quota_settler);
        let outbox_enqueuer = Arc::clone(&self.outbox_enqueuer);

        let tx_result = self
            .db
            .transaction(|tx| {
                Box::pin(async move {
                    // 1. CAS finalize orphan (re-checks all predicates)
                    let rows = turn_repo
                        .cas_finalize_orphan(tx, input.turn_id, timeout_secs)
                        .await
                        .map_err(to_db)?;

                    if rows == 0 {
                        debug!(
                            turn_id = %input.turn_id,
                            "orphan CAS loser: turn already finalized or progress renewed"
                        );
                        return Ok(false);
                    }

                    // 2. Derive billing outcome (pure function)
                    let billing = derive_billing_outcome(&BillingDerivationInput {
                        terminal_state: TurnState::Failed,
                        error_code: Some("orphan_timeout".to_owned()),
                        has_usage: false,
                    });

                    // 3. Settle quota if all required fields are present.
                    let quota_fields = input
                        .effective_model
                        .as_ref()
                        .zip(input.user_id)
                        .zip(input.reserve_tokens)
                        .zip(input.policy_version_applied)
                        .map(|(((em, uid), rt), pv)| (em.clone(), uid, rt, pv));

                    let settlement_outcome = if let Some((
                        effective_model,
                        user_id_val,
                        reserve_tokens,
                        policy_version_applied,
                    )) = quota_fields
                    {
                        let day = input.started_at.date();
                        // replace_day(1) is infallible for any valid Date, but the
                        // `time` crate returns Result so we propagate defensively.
                        let month_start = day
                            .replace_day(1)
                            .map_err(|e| to_db(DomainError::internal(e.to_string())))?;
                        let period_starts =
                            vec![(PeriodType::Daily, day), (PeriodType::Monthly, month_start)];

                        let settlement_input = SettlementInput {
                            tenant_id: input.tenant_id,
                            user_id: user_id_val,
                            effective_model,
                            policy_version_applied,
                            reserve_tokens,
                            max_output_tokens_applied: input.max_output_tokens_applied.unwrap_or(0),
                            reserved_credits_micro: input.reserved_credits_micro.unwrap_or(0),
                            minimal_generation_floor_applied: input
                                .minimal_generation_floor_applied
                                .unwrap_or(0),
                            settlement_path: SettlementPath::Estimated,
                            period_starts,
                            web_search_calls: input.web_search_completed_count,
                            code_interpreter_calls: input.code_interpreter_completed_count,
                        };

                        let scope = toolkit_security::AccessScope::allow_all();
                        let outcome = quota_settler
                            .settle_in_tx(tx, &scope, settlement_input)
                            .await
                            .map_err(to_db)?;
                        Some(outcome)
                    } else {
                        warn!(
                            turn_id = %input.turn_id,
                            "orphan turn missing quota fields, skipping settlement"
                        );
                        None
                    };

                    // 4. Build and enqueue usage event
                    let now = time::OffsetDateTime::now_utc();
                    let effective_model_str = input.effective_model.clone().unwrap_or_default();
                    // Nil UUID for system requesters or turns without a user — the turn
                    // row may have NULL requester_user_id for system-initiated turns.
                    // Acceptable because billing settles by tenant, not user.
                    let user_id = input.user_id.unwrap_or(Uuid::nil());

                    let settlement_method_str =
                        settlement_outcome.as_ref().map_or("estimated", |s| {
                            match s.settlement_method {
                                SettlementMethod::Actual => "actual",
                                SettlementMethod::Estimated => "estimated",
                                SettlementMethod::Released => "released",
                            }
                        });

                    let actual_credits_micro = settlement_outcome
                        .as_ref()
                        .map_or(0, |s| s.actual_credits_micro);

                    let usage_event = UsageEvent {
                        tenant_id: input.tenant_id,
                        user_id: input.user_id,
                        chat_id: input.chat_id,
                        turn_id: Some(input.turn_id),
                        request_id: input.request_id,
                        effective_model: effective_model_str.clone(),
                        selected_model: effective_model_str.clone(),
                        terminal_state: "failed".to_owned(),
                        billing_outcome: billing.outcome.as_str().to_owned(),
                        usage: None,
                        actual_credits_micro,
                        settlement_method: settlement_method_str.to_owned(),
                        policy_version_applied: input.policy_version_applied.unwrap_or(0),
                        web_search_calls: input.web_search_completed_count,
                        code_interpreter_calls: input.code_interpreter_completed_count,
                        file_search_calls: input.file_search_completed_count,
                        timestamp: now,
                        requester_type: "user".to_owned(),
                        dedupe_key: None,
                        system_task_type: None,
                    };
                    outbox_enqueuer
                        .enqueue_usage_event(tx, usage_event)
                        .await
                        .map_err(to_db)?;

                    // 5. Build and enqueue audit event
                    let audit_event = AuditEnvelope::Turn(TurnAuditEvent {
                        event_type: TurnAuditEventType::TurnFailed,
                        timestamp: now,
                        tenant_id: input.tenant_id,
                        requester_type: input.requester_type,
                        trace_id: None,
                        user_id,
                        chat_id: input.chat_id,
                        turn_id: input.turn_id,
                        request_id: input.request_id,
                        selected_model: effective_model_str.clone(),
                        effective_model: effective_model_str.clone(),
                        policy_version_applied: input
                            .policy_version_applied
                            .map(i64::cast_unsigned),
                        usage: AuditUsageTokens {
                            input_tokens: 0,
                            output_tokens: 0,
                            model: Some(effective_model_str),
                            cache_read_input_tokens: Some(0),
                            cache_write_input_tokens: Some(0),
                            reasoning_tokens: Some(0),
                        },
                        latency_ms: LatencyMs {
                            ttft_ms: None,
                            total_ms: None,
                        },
                        policy_decisions: PolicyDecisions {
                            license: None,
                            quota: QuotaDecision {
                                decision: "unknown".to_owned(),
                                quota_scope: None,
                                downgrade_from: None,
                                downgrade_reason: None,
                            },
                        },
                        error_code: Some("orphan_timeout".to_owned()),
                        prompt: None,
                        response: None,
                        attachments: Vec::new(),
                        tool_calls: None,
                    });
                    outbox_enqueuer
                        .enqueue_audit_event(tx, audit_event)
                        .await
                        .map_err(to_db)?;

                    Ok(true)
                })
            })
            .await
            .map_err(DomainError::from)?;

        // Post-commit side effects (outside transaction).
        if tx_result {
            self.outbox_enqueuer.flush();
            let ms = start.elapsed().as_secs_f64() * 1000.0;
            self.metrics.record_audit_emit(result_label::OK);
            self.metrics.record_finalization_latency_ms(ms);
            self.metrics.record_streams_aborted(trigger::ORPHAN_TIMEOUT);
        }

        Ok(tx_result)
    }
}

fn build_turn_audit_envelope(input: &FinalizationInput, trace_id: Option<String>) -> AuditEnvelope {
    let event_type = match input.terminal_state {
        TurnState::Completed => TurnAuditEventType::TurnCompleted,
        _ => TurnAuditEventType::TurnFailed,
    };

    let usage = input.usage.unwrap_or(Usage {
        input_tokens: 0,
        output_tokens: 0,
        cache_read_input_tokens: 0,
        cache_write_input_tokens: 0,
        reasoning_tokens: 0,
    });

    AuditEnvelope::Turn(TurnAuditEvent {
        event_type,
        timestamp: time::OffsetDateTime::now_utc(),
        tenant_id: input.tenant_id,
        requester_type: input.requester_type,
        trace_id,
        user_id: input.user_id,
        chat_id: input.chat_id,
        turn_id: input.turn_id,
        request_id: input.request_id,
        selected_model: input.selected_model.clone(),
        effective_model: input.effective_model.clone(),
        policy_version_applied: Some(input.policy_version_applied.cast_unsigned()),
        usage: AuditUsageTokens {
            input_tokens: usage.input_tokens.cast_unsigned(),
            output_tokens: usage.output_tokens.cast_unsigned(),
            model: Some(input.effective_model.clone()),
            cache_read_input_tokens: Some(usage.cache_read_input_tokens.cast_unsigned()),
            cache_write_input_tokens: Some(usage.cache_write_input_tokens.cast_unsigned()),
            reasoning_tokens: Some(usage.reasoning_tokens.cast_unsigned()),
        },
        latency_ms: LatencyMs {
            ttft_ms: input.ttft_ms,
            total_ms: input.total_ms,
        },
        policy_decisions: PolicyDecisions {
            license: None,
            quota: QuotaDecision {
                decision: input.quota_decision.clone(),
                quota_scope: None,
                downgrade_from: input.downgrade_from.clone(),
                downgrade_reason: input.downgrade_reason.clone(),
            },
        },
        error_code: input.error_code.clone(),
        prompt: None,
        response: None,
        attachments: Vec::new(),
        tool_calls: None,
    })
}

fn build_usage_event(
    input: &FinalizationInput,
    billing: BillingDerivation,
    settlement: &SettlementOutcome,
) -> UsageEvent {
    let terminal_state = match input.terminal_state {
        TurnState::Running => "running",
        TurnState::Completed => "completed",
        TurnState::Failed => "failed",
        TurnState::Cancelled => "cancelled",
    };
    let settlement_method = match settlement.settlement_method {
        SettlementMethod::Actual => "actual",
        SettlementMethod::Estimated => "estimated",
        SettlementMethod::Released => "released",
    };
    UsageEvent {
        tenant_id: input.tenant_id,
        user_id: Some(input.user_id),
        chat_id: input.chat_id,
        turn_id: Some(input.turn_id),
        request_id: input.request_id,
        effective_model: input.effective_model.clone(),
        selected_model: input.selected_model.clone(),
        terminal_state: terminal_state.to_owned(),
        billing_outcome: billing.outcome.as_str().to_owned(),
        usage: input.usage.map(|u| UsageTokens {
            input_tokens: u.input_tokens.cast_unsigned(),
            output_tokens: u.output_tokens.cast_unsigned(),
            cache_read_input_tokens: u.cache_read_input_tokens.cast_unsigned(),
            cache_write_input_tokens: u.cache_write_input_tokens.cast_unsigned(),
            reasoning_tokens: u.reasoning_tokens.cast_unsigned(),
        }),
        actual_credits_micro: settlement.actual_credits_micro,
        settlement_method: settlement_method.to_owned(),
        policy_version_applied: input.policy_version_applied,
        web_search_calls: input.web_search_calls,
        code_interpreter_calls: input.code_interpreter_calls,
        file_search_calls: input.file_search_calls,
        timestamp: time::OffsetDateTime::now_utc(),
        requester_type: "user".to_owned(),
        dedupe_key: None,
        system_task_type: None,
    }
}

/// Internal error type to distinguish message persistence failure
/// from other domain errors, enabling the retry-as-failed logic.
#[domain_model]
enum FinalizationError {
    Domain(DomainError),
    MessagePersistenceFailed(String),
}

#[cfg(test)]
mod trigger_tests {
    use super::should_trigger_summary;

    #[test]
    fn proactive_fires_above_threshold_no_summary() {
        // 2000 tokens, budget=3072 (4096-1024), 60% threshold=1843
        assert!(should_trigger_summary(2000, 1024, 4096, 60, false, false));
    }

    #[test]
    fn proactive_skipped_below_threshold() {
        // 1000 tokens < 1843 threshold
        assert!(!should_trigger_summary(1000, 1024, 4096, 60, false, false));
    }

    #[test]
    fn proactive_suppressed_when_summary_exists() {
        // Above threshold but summary already exists — skip
        assert!(!should_trigger_summary(2000, 1024, 4096, 60, false, true));
    }

    #[test]
    fn urgent_fires_when_truncated_even_with_summary() {
        // messages_truncated=true overrides everything
        assert!(should_trigger_summary(500, 1024, 4096, 60, true, true));
    }

    #[test]
    fn non_positive_budget_returns_false() {
        // max_output >= context_window → effective_budget <= 0
        assert!(!should_trigger_summary(1000, 5000, 4096, 60, false, false));
    }

    #[test]
    fn zero_tokens_returns_false() {
        assert!(!should_trigger_summary(0, 1024, 4096, 60, false, false));
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::domain::llm::Usage;
    use crate::domain::model::finalization::FinalizationInput;
    use crate::domain::model::quota::{SettlementMethod, SettlementOutcome};
    use crate::domain::repos::{CreateTurnParams, TurnRepository as TurnRepoTrait};
    use crate::domain::service::AuditEnvelope;
    use crate::domain::service::test_helpers::{
        RecordingOutboxEnqueuer, inmem_db, mock_db_provider,
    };
    use crate::infra::db::entity::chat_turn::TurnState;
    use crate::infra::db::entity::quota_usage::PeriodType;
    use crate::infra::db::repo::message_repo::MessageRepository as MsgRepo;
    use crate::infra::db::repo::turn_repo::TurnRepository as TurnRepo;
    use toolkit_security::AccessScope;
    use uuid::Uuid;

    // ── Mock QuotaSettler ──

    #[domain_model]
    struct MockQuotaSettler;

    #[async_trait::async_trait]
    impl QuotaSettler for MockQuotaSettler {
        async fn settle_in_tx(
            &self,
            _tx: &toolkit_db::secure::DbTx<'_>,
            _scope: &AccessScope,
            _input: crate::domain::model::quota::SettlementInput,
        ) -> Result<SettlementOutcome, DomainError> {
            Ok(SettlementOutcome {
                settlement_method: SettlementMethod::Actual,
                actual_credits_micro: 500,
                charged_tokens: 15,
                overshoot_capped: false,
            })
        }
    }

    // ── Noop OutboxEnqueuer (with flush tracking) ──

    #[domain_model]
    struct NoopOutboxEnqueuer {
        flush_count: std::sync::atomic::AtomicU32,
    }

    impl NoopOutboxEnqueuer {
        fn new() -> Self {
            Self {
                flush_count: std::sync::atomic::AtomicU32::new(0),
            }
        }

        #[allow(dead_code)]
        fn flush_count(&self) -> u32 {
            self.flush_count.load(std::sync::atomic::Ordering::Relaxed)
        }
    }

    #[async_trait::async_trait]
    impl OutboxEnqueuer for NoopOutboxEnqueuer {
        async fn enqueue_usage_event(
            &self,
            _runner: &(dyn toolkit_db::secure::DBRunner + Sync),
            _event: mini_chat_sdk::UsageEvent,
        ) -> Result<(), DomainError> {
            Ok(())
        }

        async fn enqueue_attachment_cleanup(
            &self,
            _runner: &(dyn toolkit_db::secure::DBRunner + Sync),
            _event: crate::domain::repos::AttachmentCleanupEvent,
        ) -> Result<(), DomainError> {
            Ok(())
        }

        async fn enqueue_chat_cleanup(
            &self,
            _runner: &(dyn toolkit_db::secure::DBRunner + Sync),
            _event: crate::domain::repos::ChatCleanupEvent,
        ) -> Result<(), DomainError> {
            Ok(())
        }

        async fn enqueue_audit_event(
            &self,
            _runner: &(dyn toolkit_db::secure::DBRunner + Sync),
            _event: crate::domain::model::audit_envelope::AuditEnvelope,
        ) -> Result<(), DomainError> {
            Ok(())
        }

        async fn enqueue_thread_summary(
            &self,
            _: &(dyn toolkit_db::secure::DBRunner + Sync),
            _: crate::domain::repos::ThreadSummaryTaskPayload,
        ) -> Result<(), DomainError> {
            Ok(())
        }

        fn flush(&self) {
            self.flush_count
                .fetch_add(1, std::sync::atomic::Ordering::Relaxed);
        }
    }

    fn build_finalization_service(
        db: Arc<DbProvider>,
    ) -> (
        FinalizationService<TurnRepo, MsgRepo>,
        Arc<RecordingOutboxEnqueuer>,
    ) {
        let outbox = Arc::new(RecordingOutboxEnqueuer::new());
        let svc = FinalizationService::new(
            db,
            Arc::new(TurnRepo),
            Arc::new(MsgRepo::new(toolkit_db::odata::LimitCfg {
                default: 20,
                max: 100,
            })),
            Arc::new(MockQuotaSettler),
            outbox.clone(),
            Arc::new(crate::domain::ports::metrics::NoopMetrics),
            crate::config::background::ThreadSummaryWorkerConfig::default(),
        );
        (svc, outbox)
    }

    fn build_finalization_service_with_metrics(
        db: Arc<DbProvider>,
        metrics: Arc<dyn MiniChatMetricsPort>,
    ) -> (
        FinalizationService<TurnRepo, MsgRepo>,
        Arc<NoopOutboxEnqueuer>,
    ) {
        let outbox = Arc::new(NoopOutboxEnqueuer::new());
        let svc = FinalizationService::new(
            db,
            Arc::new(TurnRepo),
            Arc::new(MsgRepo::new(toolkit_db::odata::LimitCfg {
                default: 20,
                max: 100,
            })),
            Arc::new(MockQuotaSettler),
            outbox.clone(),
            metrics,
            crate::config::background::ThreadSummaryWorkerConfig::default(),
        );
        (svc, outbox)
    }

    /// Insert a parent chat row (FK constraint).
    async fn insert_test_chat(db: &Arc<DbProvider>, tenant_id: Uuid, chat_id: Uuid, user_id: Uuid) {
        use crate::infra::db::entity::chat::{ActiveModel, Entity as ChatEntity};
        use sea_orm::Set;
        use time::OffsetDateTime;
        use toolkit_db::secure::secure_insert;

        let now = OffsetDateTime::now_utc();
        let am = ActiveModel {
            id: Set(chat_id),
            tenant_id: Set(tenant_id),
            user_id: Set(user_id),
            model: Set("gpt-5.2".to_owned()),
            title: Set(Some("test".to_owned())),
            is_temporary: Set(false),
            created_at: Set(now),
            updated_at: Set(now),
            deleted_at: Set(None),
        };
        let conn = db.conn().unwrap();
        secure_insert::<ChatEntity>(am, &AccessScope::allow_all(), &conn)
            .await
            .expect("insert chat");
    }

    /// Insert a turn in `running` state.
    async fn insert_running_turn(
        db: &Arc<DbProvider>,
        tenant_id: Uuid,
        chat_id: Uuid,
        turn_id: Uuid,
        request_id: Uuid,
    ) {
        let conn = db.conn().unwrap();
        let scope = AccessScope::allow_all();
        let turn_repo = TurnRepo;
        turn_repo
            .create_turn(
                &conn,
                &scope,
                CreateTurnParams {
                    id: turn_id,
                    tenant_id,
                    chat_id,
                    request_id,
                    requester_type: "user".to_owned(),
                    requester_user_id: None,
                    reserve_tokens: Some(100),
                    max_output_tokens_applied: Some(4096),
                    reserved_credits_micro: Some(1000),
                    policy_version_applied: Some(1),
                    effective_model: Some("gpt-5.2".to_owned()),
                    minimal_generation_floor_applied: Some(10),
                    web_search_enabled: false,
                },
            )
            .await
            .expect("create turn");
    }

    fn make_input(
        tenant_id: Uuid,
        chat_id: Uuid,
        turn_id: Uuid,
        request_id: Uuid,
        user_id: Uuid,
        terminal_state: TurnState,
    ) -> FinalizationInput {
        let today = time::OffsetDateTime::now_utc().date();
        let month_start = today.replace_day(1).unwrap();
        FinalizationInput {
            turn_id,
            tenant_id,
            chat_id,
            request_id,
            user_id,
            requester_type: mini_chat_sdk::RequesterType::User,
            scope: AccessScope::allow_all(),
            message_id: Uuid::new_v4(),
            terminal_state,
            error_code: None,
            error_detail: None,
            accumulated_text: "Hello, world!".to_owned(),
            usage: Some(Usage {
                input_tokens: 10,
                output_tokens: 5,
                cache_read_input_tokens: 0,
                cache_write_input_tokens: 0,
                reasoning_tokens: 0,
            }),
            provider_response_id: Some("resp-123".to_owned()),
            effective_model: "gpt-5.2".to_owned(),
            selected_model: "gpt-5.2".to_owned(),
            reserve_tokens: 100,
            max_output_tokens_applied: 4096,
            reserved_credits_micro: 1000,
            policy_version_applied: 1,
            minimal_generation_floor_applied: 10,
            quota_decision: "allow".to_owned(),
            downgrade_from: None,
            downgrade_reason: None,
            period_starts: vec![
                (PeriodType::Daily, today),
                (PeriodType::Monthly, month_start),
            ],
            web_search_calls: 3,
            code_interpreter_calls: 0,
            file_search_calls: 0,
            context_window: 128_000,
            assembled_context_tokens: 0,
            messages_truncated: false,
            ttft_ms: None,
            total_ms: None,
        }
    }

    /// Backdate `last_progress_at` on a turn to 10 minutes ago, making it orphan-eligible.
    async fn backdate_turn_progress(runner: &impl toolkit_db::secure::DBRunner, turn_id: Uuid) {
        use crate::infra::db::entity::chat_turn::{Column, Entity as TurnEntity};
        use sea_orm::{ColumnTrait, EntityTrait, QueryFilter, sea_query::Expr};
        use time::OffsetDateTime;
        use toolkit_db::secure::SecureUpdateExt;

        let past = OffsetDateTime::now_utc() - time::Duration::seconds(600);
        let scope = AccessScope::allow_all();
        TurnEntity::update_many()
            .col_expr(Column::LastProgressAt, Expr::value(Some(past)))
            .filter(Column::Id.eq(turn_id))
            .secure()
            .scope_with(&scope)
            .exec(runner)
            .await
            .expect("backdate last_progress_at");
    }

    // ── 3.6: CAS winner executes full atomic finalization ──

    #[tokio::test]
    async fn cas_winner_completes_finalization() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        let outcome = svc
            .finalize_turn_cas(input)
            .await
            .expect("finalization should succeed");

        assert!(outcome.won_cas, "should be CAS winner");
        assert!(outcome.billing_outcome.is_some());
        assert!(outcome.settlement_outcome.is_some());
        assert_eq!(
            outbox.flush_count(),
            1,
            "flush should be called once after CAS win"
        );

        // Verify turn is now in completed state
        let conn = db.conn().unwrap();
        let scope = AccessScope::allow_all();
        let turn_repo = TurnRepo;
        let turn = turn_repo
            .find_by_chat_and_request_id(&conn, &scope, chat_id, request_id)
            .await
            .expect("find turn")
            .expect("turn should exist");
        assert_eq!(turn.state, TurnState::Completed);
    }

    // ── 3.7: CAS loser returns won_cas = false ──

    #[tokio::test]
    async fn cas_loser_returns_no_side_effects() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        // First finalization — wins CAS
        let input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        let outcome1 = svc
            .finalize_turn_cas(input)
            .await
            .expect("first finalization");
        assert!(outcome1.won_cas);

        // Second finalization — loses CAS (turn already completed)
        let input2 = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Failed,
        );
        let outcome2 = svc
            .finalize_turn_cas(input2)
            .await
            .expect("second finalization");
        assert!(!outcome2.won_cas, "second finalizer should lose CAS");
        assert!(outcome2.billing_outcome.is_none());
        assert!(outcome2.settlement_outcome.is_none());
        // First call won CAS → 1 flush. Second lost CAS → no additional flush.
        assert_eq!(
            outbox.flush_count(),
            1,
            "flush should only be called for CAS winner"
        );
    }

    // ── 3.8: Transaction rollback on failure leaves turn in running state ──

    #[tokio::test]
    async fn failed_settlement_leaves_turn_running() {
        // Use a QuotaSettler that always fails
        #[domain_model]
        struct FailingQuotaSettler;

        #[async_trait::async_trait]
        impl QuotaSettler for FailingQuotaSettler {
            async fn settle_in_tx(
                &self,
                _tx: &toolkit_db::secure::DbTx<'_>,
                _scope: &AccessScope,
                _input: crate::domain::model::quota::SettlementInput,
            ) -> Result<SettlementOutcome, DomainError> {
                Err(DomainError::internal("settlement exploded"))
            }
        }

        let db = mock_db_provider(inmem_db().await);
        let svc = FinalizationService::new(
            Arc::clone(&db),
            Arc::new(TurnRepo),
            Arc::new(MsgRepo::new(toolkit_db::odata::LimitCfg {
                default: 20,
                max: 100,
            })),
            Arc::new(FailingQuotaSettler),
            Arc::new(RecordingOutboxEnqueuer::new()),
            Arc::new(crate::domain::ports::metrics::NoopMetrics),
            crate::config::background::ThreadSummaryWorkerConfig::default(),
        );

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        let result = svc.finalize_turn_cas(input).await;

        // Should fail due to settlement error
        assert!(
            result.is_err(),
            "finalization should fail when settlement fails"
        );

        // Verify turn is still running (transaction rolled back)
        let conn = db.conn().unwrap();
        let scope = AccessScope::allow_all();
        let turn_repo = TurnRepo;
        let running = turn_repo
            .find_running_by_chat_id(&conn, &scope, chat_id)
            .await
            .expect("find running turn")
            .expect("turn should still be running");
        assert_eq!(running.id, turn_id);
        assert_eq!(running.state, TurnState::Running);
    }

    // ── Metrics emission on successful finalization ──

    #[tokio::test]
    async fn cas_winner_emits_audit_and_quota_metrics() {
        use crate::domain::service::test_helpers::TestMetrics;
        use std::sync::atomic::Ordering;

        let db = mock_db_provider(inmem_db().await);
        let metrics = Arc::new(TestMetrics::new());
        let (svc, _outbox) =
            build_finalization_service_with_metrics(Arc::clone(&db), Arc::clone(&metrics) as _);

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        let outcome = svc
            .finalize_turn_cas(input)
            .await
            .expect("finalization should succeed");
        assert!(outcome.won_cas);

        // Audit emission metrics
        assert_eq!(
            metrics.audit_emit.load(Ordering::Relaxed),
            1,
            "should record audit_emit"
        );
        assert_eq!(
            metrics.finalization_latency_ms.load(Ordering::Relaxed),
            1,
            "should record finalization_latency_ms"
        );
        // Quota settlement metrics (daily + monthly)
        assert_eq!(
            metrics.quota_commit.load(Ordering::Relaxed),
            2,
            "should record quota_commit for daily + monthly"
        );
        assert_eq!(
            metrics.quota_actual_tokens.load(Ordering::Relaxed),
            1,
            "should record quota_actual_tokens"
        );
    }

    #[tokio::test]
    async fn cas_winner_emits_code_interpreter_calls_metric() {
        use crate::domain::service::test_helpers::TestMetrics;
        use std::sync::atomic::Ordering;

        let db = mock_db_provider(inmem_db().await);
        let metrics = Arc::new(TestMetrics::new());
        let (svc, _outbox) =
            build_finalization_service_with_metrics(Arc::clone(&db), Arc::clone(&metrics) as _);

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let mut input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        input.code_interpreter_calls = 5;

        let outcome = svc
            .finalize_turn_cas(input)
            .await
            .expect("finalization should succeed");
        assert!(outcome.won_cas);

        assert_eq!(
            metrics.code_interpreter_calls.load(Ordering::Relaxed),
            1,
            "should record code_interpreter_calls metric"
        );
    }

    // ── Cancelled message persistence tests (D4) ──

    #[tokio::test]
    async fn cancelled_with_text_persists_message() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, _outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let mut input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Cancelled,
        );
        input.accumulated_text = "partial response content".to_owned();
        input.usage = None;

        let outcome = svc
            .finalize_turn_cas(input)
            .await
            .expect("finalization should succeed");

        assert!(outcome.won_cas);

        // Verify turn is cancelled with assistant_message_id set
        let conn = db.conn().unwrap();
        let scope = AccessScope::allow_all();
        let turn_repo = TurnRepo;
        let turn = turn_repo
            .find_by_chat_and_request_id(&conn, &scope, chat_id, request_id)
            .await
            .expect("find turn")
            .expect("turn should exist");
        assert_eq!(turn.state, TurnState::Cancelled);
        assert!(
            turn.assistant_message_id.is_some(),
            "cancelled turn with text should have assistant_message_id"
        );
    }

    #[tokio::test]
    async fn cancelled_without_text_does_not_persist_message() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, _outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let mut input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Cancelled,
        );
        input.accumulated_text = String::new();
        input.usage = None;

        let outcome = svc
            .finalize_turn_cas(input)
            .await
            .expect("finalization should succeed");

        assert!(outcome.won_cas);

        let conn = db.conn().unwrap();
        let scope = AccessScope::allow_all();
        let turn_repo = TurnRepo;
        let turn = turn_repo
            .find_by_chat_and_request_id(&conn, &scope, chat_id, request_id)
            .await
            .expect("find turn")
            .expect("turn should exist");
        assert_eq!(turn.state, TurnState::Cancelled);
        assert!(
            turn.assistant_message_id.is_none(),
            "cancelled turn without text should have no assistant_message_id"
        );
    }

    #[tokio::test]
    async fn completed_message_persist_failure_retries_as_failed() {
        // Existing behavior unchanged — verify the guard doesn't break it.
        // We test by finalizing as Completed, then finalizing again (CAS loser
        // path), confirming the first finalization worked correctly.
        let db = mock_db_provider(inmem_db().await);
        let (svc, _outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        let outcome = svc
            .finalize_turn_cas(input)
            .await
            .expect("finalization should succeed");
        assert!(outcome.won_cas);

        let conn = db.conn().unwrap();
        let scope = AccessScope::allow_all();
        let turn_repo = TurnRepo;
        let turn = turn_repo
            .find_by_chat_and_request_id(&conn, &scope, chat_id, request_id)
            .await
            .expect("find turn")
            .expect("turn should exist");
        assert_eq!(turn.state, TurnState::Completed);
        assert!(turn.assistant_message_id.is_some());
    }

    // ── Audit emission tests ──

    #[tokio::test]
    async fn cas_winner_emits_turn_completed_audit() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        let outcome = svc.finalize_turn_cas(input).await.unwrap();
        assert!(outcome.won_cas);

        let captured = outbox.audit_events();
        assert_eq!(captured.len(), 1, "expected exactly 1 audit event");
        match &captured[0] {
            AuditEnvelope::Turn(evt) => {
                assert_eq!(
                    evt.event_type,
                    mini_chat_sdk::TurnAuditEventType::TurnCompleted
                );
                assert_eq!(evt.tenant_id, tenant_id);
                assert_eq!(evt.user_id, user_id);
                assert_eq!(evt.chat_id, chat_id);
                assert_eq!(evt.turn_id, turn_id);
                assert_eq!(evt.request_id, request_id);
                assert_eq!(evt.effective_model, "gpt-5.2");
                assert_eq!(evt.selected_model, "gpt-5.2");
                assert_eq!(evt.usage.input_tokens, 10);
                assert_eq!(evt.usage.output_tokens, 5);
                assert!(evt.prompt.is_none(), "prompt should be deferred (None)");
                assert!(evt.response.is_none(), "response should be deferred (None)");
                assert!(evt.tool_calls.is_none(), "tool_calls should be None");
            }
            other => panic!("expected Turn event, got: {other:?}"),
        }
    }

    #[tokio::test]
    async fn cas_winner_emits_turn_failed_audit() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let mut input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Failed,
        );
        input.error_code = Some("provider_error".to_owned());

        let outcome = svc.finalize_turn_cas(input).await.unwrap();
        assert!(outcome.won_cas);

        let captured = outbox.audit_events();
        assert_eq!(captured.len(), 1);
        match &captured[0] {
            AuditEnvelope::Turn(evt) => {
                assert_eq!(
                    evt.event_type,
                    mini_chat_sdk::TurnAuditEventType::TurnFailed
                );
                assert_eq!(evt.error_code, Some("provider_error".to_owned()));
            }
            other => panic!("expected Turn event, got: {other:?}"),
        }
    }

    #[tokio::test]
    async fn cas_loser_does_not_emit_audit() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        // First finalization wins CAS
        let input1 = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        svc.finalize_turn_cas(input1).await.unwrap();
        outbox.clear_audit_events();

        // Second finalization loses CAS — no audit
        let input2 = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Failed,
        );
        let outcome2 = svc.finalize_turn_cas(input2).await.unwrap();
        assert!(!outcome2.won_cas);

        assert!(
            outbox.audit_events().is_empty(),
            "CAS loser must not emit audit events"
        );
    }

    #[tokio::test]
    async fn audit_event_includes_latency_when_provided() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let mut input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        input.ttft_ms = Some(120);
        input.total_ms = Some(3500);

        svc.finalize_turn_cas(input).await.unwrap();

        let captured = outbox.audit_events();
        match &captured[0] {
            AuditEnvelope::Turn(evt) => {
                assert_eq!(evt.latency_ms.ttft_ms, Some(120));
                assert_eq!(evt.latency_ms.total_ms, Some(3500));
            }
            other => panic!("expected Turn event, got: {other:?}"),
        }
    }

    #[tokio::test]
    async fn audit_event_policy_decisions_match_input() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let mut input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        input.quota_decision = "downgrade".to_owned();
        input.downgrade_from = Some("gpt-5.2".to_owned());
        input.downgrade_reason = Some("quota exceeded".to_owned());

        svc.finalize_turn_cas(input).await.unwrap();

        let captured = outbox.audit_events();
        match &captured[0] {
            AuditEnvelope::Turn(evt) => {
                assert_eq!(evt.policy_decisions.quota.decision, "downgrade");
                assert_eq!(
                    evt.policy_decisions.quota.downgrade_from,
                    Some("gpt-5.2".to_owned())
                );
                assert_eq!(
                    evt.policy_decisions.quota.downgrade_reason,
                    Some("quota exceeded".to_owned())
                );
                assert_eq!(evt.policy_version_applied, Some(1));
            }
            other => panic!("expected Turn event, got: {other:?}"),
        }
    }

    // ── Token breakdown fields propagate through finalization ──

    #[tokio::test]
    async fn finalization_propagates_token_breakdown_fields() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let mut input = make_input(
            tenant_id,
            chat_id,
            turn_id,
            request_id,
            user_id,
            TurnState::Completed,
        );
        input.usage = Some(Usage {
            input_tokens: 100,
            output_tokens: 50,
            cache_read_input_tokens: 42,
            cache_write_input_tokens: 17,
            reasoning_tokens: 88,
        });

        svc.finalize_turn_cas(input).await.unwrap();

        // ── Verify usage event ──
        let usage_events = outbox.usage_events.lock().unwrap();
        assert_eq!(usage_events.len(), 1);
        let usage = usage_events[0]
            .usage
            .as_ref()
            .expect("usage should be present");
        assert_eq!(usage.cache_read_input_tokens, 42);
        assert_eq!(usage.cache_write_input_tokens, 17);
        assert_eq!(usage.reasoning_tokens, 88);
        drop(usage_events);

        // ── Verify audit event ──
        let audit_events = outbox.audit_events();
        assert_eq!(audit_events.len(), 1);
        match &audit_events[0] {
            AuditEnvelope::Turn(evt) => {
                assert_eq!(evt.usage.cache_read_input_tokens, Some(42));
                assert_eq!(evt.usage.cache_write_input_tokens, Some(17));
                assert_eq!(evt.usage.reasoning_tokens, Some(88));
            }
            other => panic!("expected Turn event, got: {other:?}"),
        }
    }

    // ── Orphan finalization tests ──

    #[tokio::test]
    async fn finalize_orphan_cas_winner() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        // Make the turn stale by backdating last_progress_at
        let conn = db.conn().unwrap();
        backdate_turn_progress(&conn, turn_id).await;

        let input = crate::domain::model::finalization::OrphanFinalizationInput {
            turn_id,
            tenant_id,
            chat_id,
            request_id,
            user_id: Some(user_id),
            requester_type: mini_chat_sdk::RequesterType::User,
            effective_model: Some("gpt-5.2".to_owned()),
            reserve_tokens: Some(100),
            max_output_tokens_applied: Some(4096),
            reserved_credits_micro: Some(1000),
            policy_version_applied: Some(1),
            minimal_generation_floor_applied: Some(10),
            started_at: time::OffsetDateTime::now_utc(),
            web_search_completed_count: 0,
            code_interpreter_completed_count: 0,
            file_search_completed_count: 0,
        };

        let result = svc.finalize_orphan_turn(input, 60).await.unwrap();
        assert!(result, "should be CAS winner");

        // Verify turn state
        let scope = AccessScope::allow_all();
        let turn_repo = TurnRepo;
        let turn = turn_repo
            .find_by_chat_and_request_id(&conn, &scope, chat_id, request_id)
            .await
            .unwrap()
            .expect("turn should exist");
        assert_eq!(turn.state, TurnState::Failed);
        assert_eq!(turn.error_code.as_deref(), Some("orphan_timeout"));

        // Verify usage event enqueued
        let usage_events = outbox.usage_events.lock().unwrap();
        assert_eq!(usage_events.len(), 1, "should have one usage event");
        assert_eq!(usage_events[0].terminal_state, "failed");
        assert_eq!(usage_events[0].billing_outcome, "aborted");
        drop(usage_events);

        // Verify audit event enqueued
        let audit_events = outbox.audit_events();
        assert_eq!(audit_events.len(), 1, "should have one audit event");
        match &audit_events[0] {
            AuditEnvelope::Turn(evt) => {
                assert_eq!(
                    evt.event_type,
                    mini_chat_sdk::TurnAuditEventType::TurnFailed
                );
                assert_eq!(evt.error_code.as_deref(), Some("orphan_timeout"));
            }
            other => panic!("expected Turn event, got: {other:?}"),
        }

        // Verify flush was called
        assert_eq!(
            outbox.flush_count(),
            1,
            "flush should be called after CAS win"
        );
    }

    #[tokio::test]
    async fn finalize_orphan_tool_counts_propagate_to_usage_event() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        let conn = db.conn().unwrap();
        backdate_turn_progress(&conn, turn_id).await;

        let input = crate::domain::model::finalization::OrphanFinalizationInput {
            turn_id,
            tenant_id,
            chat_id,
            request_id,
            user_id: Some(user_id),
            requester_type: mini_chat_sdk::RequesterType::User,
            effective_model: Some("gpt-5.2".to_owned()),
            reserve_tokens: Some(100),
            max_output_tokens_applied: Some(4096),
            reserved_credits_micro: Some(1000),
            policy_version_applied: Some(1),
            minimal_generation_floor_applied: Some(10),
            started_at: time::OffsetDateTime::now_utc(),
            web_search_completed_count: 3,
            code_interpreter_completed_count: 2,
            file_search_completed_count: 4,
        };

        let result = svc.finalize_orphan_turn(input, 60).await.unwrap();
        assert!(result, "should be CAS winner");

        let usage_events = outbox.usage_events.lock().unwrap();
        assert_eq!(usage_events.len(), 1);
        assert_eq!(
            usage_events[0].web_search_calls, 3,
            "web_search_calls must reflect persisted count"
        );
        assert_eq!(
            usage_events[0].code_interpreter_calls, 2,
            "code_interpreter_calls must reflect persisted count"
        );
        assert_eq!(
            usage_events[0].file_search_calls, 4,
            "file_search_calls must reflect persisted count"
        );
    }

    #[tokio::test]
    async fn finalize_orphan_cas_loser() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        // Finalize normally first (CAS update to failed — avoids FK constraint on assistant_message_id)
        let conn = db.conn().unwrap();
        let scope = AccessScope::allow_all();
        let turn_repo = TurnRepo;
        turn_repo
            .cas_update_state(
                &conn,
                &scope,
                crate::domain::repos::CasTerminalParams {
                    turn_id,
                    state: TurnState::Failed,
                    error_code: Some("test_error".to_owned()),
                    error_detail: None,
                    assistant_message_id: None,
                    provider_response_id: None,
                },
            )
            .await
            .unwrap();

        // Now try orphan finalization — should be CAS loser
        let input = crate::domain::model::finalization::OrphanFinalizationInput {
            turn_id,
            tenant_id,
            chat_id,
            request_id,
            user_id: Some(user_id),
            requester_type: mini_chat_sdk::RequesterType::User,
            effective_model: Some("gpt-5.2".to_owned()),
            reserve_tokens: Some(100),
            max_output_tokens_applied: Some(4096),
            reserved_credits_micro: Some(1000),
            policy_version_applied: Some(1),
            minimal_generation_floor_applied: Some(10),
            started_at: time::OffsetDateTime::now_utc(),
            web_search_completed_count: 0,
            code_interpreter_completed_count: 0,
            file_search_completed_count: 0,
        };

        let result = svc.finalize_orphan_turn(input, 60).await.unwrap();
        assert!(!result, "should be CAS loser");

        // Verify no usage or audit events were enqueued
        let usage_events = outbox.usage_events.lock().unwrap();
        assert!(usage_events.is_empty(), "no usage events for CAS loser");
        drop(usage_events);

        let audit_events = outbox.audit_events();
        assert!(audit_events.is_empty(), "no audit events for CAS loser");

        assert_eq!(outbox.flush_count(), 0, "no flush for CAS loser");
    }

    #[tokio::test]
    async fn finalize_orphan_missing_quota_fields() {
        let db = mock_db_provider(inmem_db().await);
        let (svc, outbox) = build_finalization_service(Arc::clone(&db));

        let tenant_id = Uuid::new_v4();
        let chat_id = Uuid::new_v4();
        let turn_id = Uuid::new_v4();
        let request_id = Uuid::new_v4();
        let user_id = Uuid::new_v4();

        insert_test_chat(&db, tenant_id, chat_id, user_id).await;
        insert_running_turn(&db, tenant_id, chat_id, turn_id, request_id).await;

        // Make the turn stale by backdating last_progress_at
        let conn = db.conn().unwrap();
        backdate_turn_progress(&conn, turn_id).await;

        // Build input with effective_model = None → settlement will be skipped
        let input = crate::domain::model::finalization::OrphanFinalizationInput {
            turn_id,
            tenant_id,
            chat_id,
            request_id,
            user_id: Some(user_id),
            requester_type: mini_chat_sdk::RequesterType::User,
            effective_model: None, // missing
            reserve_tokens: Some(100),
            max_output_tokens_applied: Some(4096),
            reserved_credits_micro: Some(1000),
            policy_version_applied: Some(1),
            minimal_generation_floor_applied: Some(10),
            started_at: time::OffsetDateTime::now_utc(),
            web_search_completed_count: 0,
            code_interpreter_completed_count: 0,
            file_search_completed_count: 0,
        };

        let result = svc.finalize_orphan_turn(input, 60).await.unwrap();
        assert!(result, "CAS should succeed even with missing quota fields");

        // Verify turn is failed
        let scope = AccessScope::allow_all();
        let turn_repo = TurnRepo;
        let turn = turn_repo
            .find_by_chat_and_request_id(&conn, &scope, chat_id, request_id)
            .await
            .unwrap()
            .expect("turn should exist");
        assert_eq!(turn.state, TurnState::Failed);
        assert_eq!(turn.error_code.as_deref(), Some("orphan_timeout"));

        // Usage event should still be enqueued (settlement skipped, but event still sent)
        let usage_events = outbox.usage_events.lock().unwrap();
        assert_eq!(
            usage_events.len(),
            1,
            "usage event should be enqueued even without settlement"
        );
        drop(usage_events);
    }
}
