feat: implement dual-pipeline signal engine service

New service at services/signal_engine/ implementing concurrent heuristic
(deterministic scoring) and probabilistic (Bayesian inference) pipelines
that evaluate technical signals across 6 timeframes (M30-M) and produce
independent BUY/WATCH/SKIP verdicts per ticker per evaluation tick.

Components:
- Input Normalizer: multi-source data assembly with sentinel fallbacks
- Signal Library: Fibonacci, MA Stack, RSI, Cup & Handle, Elliott Wave
- Multi-Timeframe Confluence Engine: weighted scoring with D/W/M anchors
- Hard Filter Engine: macro_bias, valuation, earnings proximity gating
- Heuristic Pipeline: S_total scoring with confidence-gated verdicts
- Probabilistic Pipeline: Bayesian log-odds with regime priors, entropy
  gating, EV_R calculation, and signal correlation penalty
- Exit Engine: stop-loss, targets, trailing ATR-based stops
- Delta Analyzer: pipeline agreement tracking with rolling Redis metrics
- Output Formatter: SignalOutput contract + Recommendation schema mapping
- Worker orchestrator: concurrent pipelines with failure isolation
- Main entry point: queue polling with fail-safe config loading

Infrastructure:
- Migration 039: signal_engine_outputs table with 3 indexes
- Helm chart: signalEngine service entry (processing tier)
- Redis key: QUEUE_SIGNAL_ENGINE constant

Tests: 390 tests (unit + property-based) covering all components
Config: dual_pipeline_enabled=false by default (safe rollout)

docs/api-reference.md

@@ -142,14 +142,35 @@ Trend projection for a specific trend window.
 ### 1.5 Market Prices
 
 #### `GET /api/market/prices/{ticker}`
-Historical close prices from `market_snapshots`.
+Historical OHLCV bars from `market_snapshots`, deduplicated by bar timestamp and ordered oldest-first. Also returns 90-day high/low range.
 
 | Parameter | Type | Default | Constraints | Description |
 |-----------|------|---------|-------------|-------------|
-| `limit` | int | `30` | max `200` | Max bars returned |
+| `limit` | int | `200` | max `500` | Max bars returned |
 
 - **Path params:** `ticker` (auto-uppercased)
-- **Response:** Array of OHLCV objects ordered oldest-first
+- **Response:** `{ bars: [{ ticker, close, open, high, low, volume, bar_timestamp, captured_at }], range_90d: { low, high } }`
+
+#### `POST /api/market/backfill/{ticker}`
+Backfill daily OHLCV bars from Polygon for the last N days. Deduplicates by bar timestamp.
+
+| Parameter | Type | Default | Constraints | Description |
+|-----------|------|---------|-------------|-------------|
+| `days` | int | `90` | max `365` | Number of days to backfill |
+
+- **Path params:** `ticker` (auto-uppercased)
+- **Response:** `{ ticker, inserted, total_bars, days }`
+- **Errors:** `503` — No market data API key configured
+
+#### `POST /api/market/backfill-all`
+Backfill daily bars for all active companies from Polygon.
+
+| Parameter | Type | Default | Constraints | Description |
+|-----------|------|---------|-------------|-------------|
+| `days` | int | `90` | max `365` | Number of days to backfill |
+
+- **Response:** `{ total_inserted, tickers, details[] }` — each detail has `{ ticker, inserted }` or `{ ticker, inserted: 0, error }`
+- **Errors:** `503` — No market data API key configured
 
 ### 1.6 Recommendations
 
@@ -224,8 +245,6 @@ Get audit events for any entity type and ID.
 
 - **Path params:** `entity_type` (string), `entity_id` (string)
 - **Response:** Array of audit event objects
-- **Errors:** `404` — No audit events found
-
 
 ### 1.10 Admin: Source Health
 
@@ -331,6 +350,8 @@ Approve or reject a pending operator approval request.
 #### `GET /api/admin/trading/lockouts`
 List active symbol lockouts (news-shock, cooldown, manual).
 
+- **Response:** Array of lockout objects
+
 #### `POST /api/admin/trading/lockouts`
 Create a manual symbol lockout.
 
@@ -353,7 +374,6 @@ Update operator approval settings.
 - **Body:** `{ auto_approve_paper?: bool, require_approval_for_live?: bool, approval_timeout_minutes?: int }`
 - **Response:** Updated approval settings
 
-
 ### 1.13 Operational Dashboard
 
 #### `GET /api/ops/ingestion/throughput`
@@ -450,7 +470,7 @@ Trino catalog/schema/table/column metadata for the schema browser.
 #### `GET /api/analytics/pg-schema`
 PostgreSQL table/column metadata with primary keys, foreign keys, and row estimates.
 
-- **Response:** `{ catalog: "postgresql", schema: "public", tables[] }`
+- **Response:** `{ catalog: "postgresql", schema: "public", tables[{ name, row_estimate, columns[{ name, type, nullable, primary_key?, references?, has_default? }] }] }`
 
 #### `POST /api/analytics/pg-query`
 Run read-only SQL against PostgreSQL directly. Only SELECT statements allowed.
@@ -462,17 +482,19 @@ Run read-only SQL against PostgreSQL directly. Only SELECT statements allowed.
 #### `GET /api/analytics/saved-queries`
 List all saved queries.
 
+- **Response:** Array of `{ id, name, description, sql_text, created_by, created_at, updated_at }`
+
 #### `POST /api/analytics/saved-queries` (201)
 Save a new query.
 
 - **Body:** `{ name: string, description?: string, sql_text: string }`
+- **Response:** `{ id, name, description, sql_text, created_by, created_at }`
 
 #### `DELETE /api/analytics/saved-queries/{query_id}`
 Delete a saved query.
 
 - **Errors:** `404` — Query not found
 
-
 ### 1.16 Macro Signal Layer
 
 #### `GET /api/admin/macro/status`
@@ -501,9 +523,13 @@ List recent global events with filtering.
 | `limit` | int | `50` | max `200` | Page size |
 | `offset` | int | `0` | — | Pagination offset |
 
+- **Response:** Array of global event objects with `id`, `event_types`, `severity`, `affected_regions`, `affected_sectors`, `affected_commodities`, `summary`, `key_facts`, `estimated_duration`, `confidence`, `source_document_id`, `created_at`
+
 #### `GET /api/macro/events/{event_id}`
 Event detail with affected companies and macro impact scores.
 
+- **Path params:** `event_id` (UUID string)
+- **Response:** Global event object + `impacts[]` (each with `company_id`, `ticker`, `macro_impact_score`, `impact_direction`, `contributing_factors`, `confidence`, `legal_name`, `sector`)
 - **Errors:** `404` — Global event not found
 
 #### `GET /api/macro/impacts/{ticker}`
@@ -515,7 +541,8 @@ Macro impacts and exposure profile for a specific company.
 | `limit` | int | `50` | max `200` | Page size |
 | `offset` | int | `0` | — | Pagination offset |
 
-- **Response:** `{ exposure_profile, impacts[] }`
+- **Path params:** `ticker` (auto-uppercased)
+- **Response:** `{ exposure_profile, impacts[] }` — each impact includes `event_summary`, `event_severity`, `event_types`, `affected_regions`
 
 ### 1.18 Competitive Signal Layer
 
@@ -540,6 +567,7 @@ Historical patterns for a company.
 | `catalyst_type` | string | — | Filter by catalyst type |
 | `time_horizon` | string | — | Filter by time horizon |
 
+- **Path params:** `ticker` (string)
 - **Response:** `{ ticker, patterns[], count }`
 
 #### `GET /api/patterns/{ticker}/competitors`
@@ -555,6 +583,7 @@ Cross-company patterns showing how this company's catalysts affected competitors
 #### `GET /api/patterns/{ticker}/competitive-signals`
 Recent competitive signals targeting this company (limit 100).
 
+- **Path params:** `ticker` (string)
 - **Response:** `{ ticker, competitive_signals[], count }`
 
 #### `GET /api/patterns/{ticker}/decisions`
@@ -564,9 +593,9 @@ Major corporate decision history with trend outcomes and pattern statistics.
 |-----------|------|---------|-------------|
 | `time_horizon` | string | — | Filter by time horizon |
 
+- **Path params:** `ticker` (string)
 - **Response:** `{ ticker, decisions[], count }` — each decision includes `pattern_statistics[]`
 
-
 ### 1.20 AI Agents
 
 #### `GET /api/agents`
@@ -576,9 +605,12 @@ List all AI agent configurations.
 |-----------|------|---------|-------------|
 | `active_only` | bool | `false` | Only show active agents |
 
+- **Response:** Array of agent objects with `id`, `name`, `slug`, `purpose`, `model_provider`, `model_name`, `system_prompt`, `user_prompt_template`, `prompt_version`, `schema_version`, `temperature`, `max_tokens`, `timeout_seconds`, `max_retries`, `active`, `source`, `created_at`, `updated_at`
+
 #### `GET /api/agents/{agent_id}`
 Get a single agent configuration.
 
+- **Path params:** `agent_id` (UUID string)
 - **Errors:** `404` — Agent not found
 
 #### `POST /api/agents` (201)
@@ -603,9 +635,9 @@ Create a new user-defined agent.
 | `max_retries` | int | `2` | Max retry attempts |
 
 #### `PUT /api/agents/{agent_id}`
-Update an agent configuration. Partial updates supported.
+Update an agent configuration. Partial updates supported — only provided fields are changed.
 
-- **Body:** `AgentUpdateBody` — all fields optional (same fields as create)
+- **Body:** `AgentUpdateBody` — all fields optional (same fields as create plus `active`)
 - **Errors:** `400` — No fields to update; `404` — Agent not found
 
 #### `DELETE /api/agents/{agent_id}`
@@ -636,6 +668,8 @@ Hourly performance time-series for an agent.
 #### `GET /api/agents/{agent_id}/variants`
 List all variants for an agent, ordered by `created_at` ascending.
 
+- **Response:** Array of variant objects with `id`, `agent_id`, `variant_name`, `variant_slug`, `description`, `model_provider`, `model_name`, `system_prompt`, `user_prompt_template`, `prompt_version`, `temperature`, `max_tokens`, `context_window`, `input_token_limit`, `token_budget`, `timeout_seconds`, `max_retries`, `is_active`, `created_at`, `updated_at`
+
 #### `GET /api/agents/{agent_id}/variants/{variant_id}`
 Get a single variant.
 
@@ -680,13 +714,13 @@ Delete a variant. Cannot delete active variants.
 #### `POST /api/agents/{agent_id}/clone` (201)
 Clone an agent's configuration as a new variant with optional overrides.
 
-- **Body:** `VariantCloneBody { variant_name, variant_slug?, ...optional overrides }`
+- **Body:** `VariantCloneBody { variant_name, variant_slug?, description?, model_provider?, model_name?, system_prompt?, user_prompt_template?, prompt_version?, temperature?, max_tokens?, context_window?, input_token_limit?, token_budget?, timeout_seconds?, max_retries? }`
 - **Errors:** `404` — Agent not found; `409` — Duplicate slug
 
 #### `POST /api/agents/{agent_id}/variants/{variant_id}/clone` (201)
 Clone an existing variant as a new variant with optional overrides.
 
-- **Body:** `VariantCloneBody`
+- **Body:** `VariantCloneBody` (same as above)
 - **Errors:** `404` — Source variant not found; `409` — Duplicate slug
 
 #### `POST /api/agents/{agent_id}/variants/{variant_id}/activate`
@@ -697,6 +731,8 @@ Set a variant as the active variant for its agent. Deactivates any currently act
 #### `POST /api/agents/{agent_id}/variants/deactivate`
 Deactivate the currently active variant. Agent falls back to base configuration.
 
+- **Response:** `{ deactivated: true }`
+
 #### `GET /api/agents/{agent_id}/variants/{variant_id}/performance`
 Aggregated performance metrics for a specific variant.
 
@@ -704,6 +740,8 @@ Aggregated performance metrics for a specific variant.
 |-----------|------|---------|-------------|-------------|
 | `hours` | int | `24` | max `720` | Time window |
 
+- **Response:** Same shape as agent performance (invocations, successes, failures, durations, confidence, tokens, success_rate)
+
 #### `GET /api/agents/{agent_id}/variants/{variant_id}/performance/history`
 Hourly performance time-series for a specific variant.
 
@@ -711,6 +749,108 @@ Hourly performance time-series for a specific variant.
 |-----------|------|---------|-------------|-------------|
 | `hours` | int | `24` | max `720` | Time window |
 
+- **Response:** Array of `{ hour, invocations, successes, avg_duration_ms, avg_confidence }`
+
+### 1.22 Model Validation
+
+#### `GET /api/validation/summary`
+Latest model metric snapshot plus quality gate status.
+
+| Parameter | Type | Default | Constraints | Description |
+|-----------|------|---------|-------------|-------------|
+| `lookback` | string | `"30d"` | `7d`, `30d`, `90d`, `all` | Lookback window |
+| `horizon` | string | `"7d"` | `1h`, `6h`, `1d`, `7d`, `30d` | Prediction horizon |
+
+- **Response:** `{ snapshot: { id, generated_at, lookback_window, horizon, prediction_count, win_rate, directional_accuracy, information_coefficient, rank_information_coefficient, avg_return, avg_excess_return_vs_spy, avg_excess_return_vs_sector, calibration_error, brier_score, buy_win_rate, sell_win_rate, hold_win_rate, metadata }, gate_status }`
+- **Errors:** `400` — Invalid lookback or horizon value
+
+#### `GET /api/validation/calibration`
+Calibration table with confidence buckets showing predicted vs observed win rates.
+
+| Parameter | Type | Default | Constraints | Description |
+|-----------|------|---------|-------------|-------------|
+| `lookback` | string | `"30d"` | `7d`, `30d`, `90d`, `all` | Lookback window |
+| `horizon` | string | `"7d"` | `1h`, `6h`, `1d`, `7d`, `30d` | Prediction horizon |
+
+- **Response:** `{ buckets: [{ bucket_low, bucket_high, avg_confidence, observed_win_rate, prediction_count, miscalibrated }], lookback, horizon }`
+- Buckets: 0.50–0.60, 0.60–0.70, 0.70–0.80, 0.80–0.90, 0.90–1.00
+- `miscalibrated` is `true` when `|avg_confidence - observed_win_rate| > 0.15`
+- **Errors:** `400` — Invalid lookback or horizon value
+
+#### `GET /api/validation/ic-by-horizon`
+Information Coefficient and Rank IC per prediction horizon.
+
+| Parameter | Type | Default | Constraints | Description |
+|-----------|------|---------|-------------|-------------|
+| `lookback` | string | `"30d"` | `7d`, `30d`, `90d`, `all` | Lookback window |
+
+- **Response:** `{ horizons: [{ horizon, information_coefficient, rank_information_coefficient, prediction_count, generated_at }], lookback }`
+- Horizons ordered: `1h`, `6h`, `1d`, `7d`, `30d`
+- **Errors:** `400` — Invalid lookback value
+
+#### `GET /api/validation/gate-status`
+Quality gate evaluation detail from `risk_configs` where `name = 'model_quality_gate'`.
+
+- **Response:** `{ gate_status, updated_at }` or `{ gate_status: null, message: "No gate evaluation found..." }`
+
+### 1.23 Attribution
+
+#### `GET /api/validation/attribution/sources`
+Per-source performance metrics: win rate, IC, average return, duplicate rate.
+
+| Parameter | Type | Default | Constraints | Description |
+|-----------|------|---------|-------------|-------------|
+| `lookback` | string | `"30d"` | `7d`, `30d`, `90d`, `all` | Lookback window |
+| `horizon` | string | `"7d"` | `1h`, `6h`, `1d`, `7d`, `30d` | Prediction horizon |
+
+- **Response:** `{ sources[], lookback, horizon }`
+- **Errors:** `400` — Invalid lookback or horizon; `500` — Computation failed
+
+#### `GET /api/validation/attribution/catalysts`
+Per-catalyst-type performance metrics: win rate, IC, average return.
+
+| Parameter | Type | Default | Constraints | Description |
+|-----------|------|---------|-------------|-------------|
+| `lookback` | string | `"30d"` | `7d`, `30d`, `90d`, `all` | Lookback window |
+| `horizon` | string | `"7d"` | `1h`, `6h`, `1d`, `7d`, `30d` | Prediction horizon |
+
+- **Response:** `{ catalysts[], lookback, horizon }`
+- **Errors:** `400` — Invalid lookback or horizon; `500` — Computation failed
+
+#### `GET /api/validation/attribution/layers`
+Per-signal-layer (company, macro, competitive) performance metrics.
+
+| Parameter | Type | Default | Constraints | Description |
+|-----------|------|---------|-------------|-------------|
+| `lookback` | string | `"30d"` | `7d`, `30d`, `90d`, `all` | Lookback window |
+| `horizon` | string | `"7d"` | `1h`, `6h`, `1d`, `7d`, `30d` | Prediction horizon |
+
+- **Response:** `{ layers[], lookback, horizon }` — each layer has `avg_contribution_pct`, `dominant_win_rate`, `dominant_ic`
+- **Errors:** `400` — Invalid lookback or horizon; `500` — Computation failed
+
+### 1.24 Trading Reports
+
+#### `GET /api/reports`
+Paginated list of trading reports with optional filtering.
+
+| Parameter | Type | Default | Constraints | Description |
+|-----------|------|---------|-------------|-------------|
+| `report_type` | string | — | `daily` or `weekly` | Filter by report type |
+| `start_date` | string | — | ISO date (YYYY-MM-DD) | Filter `period_start >= this` |
+| `end_date` | string | — | ISO date (YYYY-MM-DD) | Filter `period_end <= this` |
+| `limit` | int | `20` | max `100` | Page size |
+| `offset` | int | `0` | min `0` | Pagination offset |
+
+- **Response:** Array of `{ id, report_type, period_start, period_end, validation_status, generated_at }`
+- **Errors:** `400` — Invalid `report_type` or date format
+
+#### `GET /api/reports/{report_id}`
+Fetch a single report including full `report_data` JSONB.
+
+- **Path params:** `report_id` (UUID string)
+- **Response:** `{ id, report_type, period_start, period_end, report_data, validation_status, generated_at, created_at }`
+- **Errors:** `404` — Report not found
+
 ---
 
 ## 2. Symbol Registry API
@@ -756,6 +896,7 @@ List tracked companies.
 #### `GET /companies/{company_id}`
 Get a single company.
 
+- **Path params:** `company_id` (UUID string)
 - **Errors:** `404` — Company not found
 
 #### `PUT /companies/{company_id}`
@@ -783,14 +924,18 @@ List aliases for a company.
 Create a new watchlist.
 
 - **Body:** `{ name: string, description?: string }`
+- **Response:** `{ id, name, description, active }`
 - **Errors:** `409` — Watchlist name already exists
 
 #### `GET /watchlists`
 List all watchlists.
 
+- **Response:** Array of `{ id, name, description, active }`
+
 #### `POST /watchlists/{watchlist_id}/members/{company_id}` (201)
 Add a company to a watchlist.
 
+- **Response:** `{ status: "added" }`
 - **Errors:** `409` — Already a member; `404` — Watchlist or company not found
 
 #### `GET /watchlists/{watchlist_id}/members`
@@ -814,11 +959,14 @@ Add a data source for a company.
 | `retention_days` | int | `365` | — | Data retention period |
 | `access_policy` | string | `"internal"` | `internal`, `public`, `restricted` | Access policy |
 
+- **Response:** `{ id, source_type, source_name, credibility_score, active }`
 - **Errors:** `404` — Company not found; `422` — Invalid source_type or access_policy
 
 #### `GET /companies/{company_id}/sources`
 List sources for a company.
 
+- **Response:** Array of `{ id, source_type, source_name, config, credibility_score, retention_days, access_policy, active }`
+
 ### 2.6 Exposure Profiles
 
 #### `GET /companies/{company_id}/exposure`
@@ -848,6 +996,8 @@ Create or update an exposure profile. Archives the previous active version.
 #### `GET /companies/{company_id}/exposure/history`
 Get all exposure profile versions for a company, ordered by version descending.
 
+- **Response:** Array of `ExposureProfileResponse`
+
 ### 2.7 Competitor Relationships
 
 #### `POST /companies/{company_id}/competitors` (201)
@@ -863,10 +1013,11 @@ Create a competitor relationship. Records an audit event.
 | `bidirectional` | bool | `true` | — | Bidirectional relationship |
 | `source` | string | `"manual"` | `manual`, `inferred` | Data source |
 
+- **Response:** `CompetitorRelationship { id, company_a_id, company_b_id, relationship_type, strength, bidirectional, source, active, created_at, updated_at }`
 - **Errors:** `400` — Self-reference; `404` — Company not found; `409` — Relationship already exists
 
 #### `GET /companies/{company_id}/competitors`
-List active competitor relationships, enriched with ticker and legal_name of the other company.
+List active competitor relationships, enriched with `ticker` and `legal_name` of the other company. Ordered by strength descending.
 
 - **Errors:** `404` — Company not found
 
@@ -879,6 +1030,7 @@ Update a competitor relationship. Records an audit event with previous state.
 #### `DELETE /companies/{company_id}/competitors/{relationship_id}`
 Soft-delete a competitor relationship (sets `active=false`). Records an audit event.
 
+- **Response:** `{ status: "deleted", id }`
 - **Errors:** `404` — Active relationship not found
 
 ### 2.8 Competitor Inference
@@ -923,7 +1075,7 @@ Diagnostic endpoint showing engine internals for troubleshooting.
 #### `GET /api/trading/status`
 Return current engine state.
 
-- **Response:** `{ enabled, paused, risk_tier, circuit_breaker_status, active_pool, reserve_pool, portfolio_heat, open_positions, last_decision_at }`
+- **Response:** `{ enabled, paused, risk_tier, circuit_breaker_status, active_pool, reserve_pool, portfolio_heat, open_positions, open_position_count, max_open_positions, absolute_position_cap, last_decision_at }`
 - **Errors:** `503` — Engine not initialised
 
 #### `PUT /api/trading/config`
@@ -960,7 +1112,13 @@ Resume the trading engine.
 #### `POST /api/trading/reset`
 Full paper trading reset: liquidate broker positions, cancel orders, clear trading state, reset capital.
 
-- **Body:** `{ initial_capital?: float (default 0.0) }` — if 0, uses broker balance or defaults to 100,000
+- **Body:** `CapitalRequest`
+
+| Field | Type | Default | Description |
+|-------|------|---------|-------------|
+| `initial_capital` | float | `0.0` | If 0, uses broker balance or defaults to 100,000 |
+| `reserve_pct` | float | `null` | Reserve pool percentage (0–1). If null, uses engine config `reserve_siphon_pct` |
+
 - **Response:** `{ reset: true, initial_capital, active_pool, reserve_pool, broker: { orders_cancelled, positions_closed, portfolio_value, cash, buying_power } }`
 - **Errors:** `503` — Engine not initialised; `500` — Database reset failed
 
@@ -977,6 +1135,8 @@ Return recent trading decisions from the database.
 | `limit` | int | `50` | max `200` | Page size |
 | `offset` | int | `0` | — | Pagination offset |
 
+- **Response:** Array of `{ id, recommendation_id, decision, skip_reason, ticker, computed_position_size, computed_share_quantity, risk_tier_at_decision, portfolio_heat_at_decision, active_pool_at_decision, reserve_pool_at_decision, circuit_breaker_status, is_micro_trade, created_at }`
+
 ### 3.5 Performance Metrics
 
 #### `GET /api/trading/metrics`
@@ -992,6 +1152,8 @@ Return historical daily portfolio snapshots.
 |-----------|------|---------|-------------|-------------|
 | `limit` | int | `30` | max `365` | Max snapshots |
 
+- **Response:** Array of `{ id, snapshot_date, portfolio_value, active_pool, reserve_pool, daily_return, cumulative_return, unrealized_pnl, realized_pnl, win_count, loss_count, win_rate, sharpe_ratio, max_drawdown, current_drawdown_pct, portfolio_heat, risk_tier, created_at }`
+
 ### 3.6 Backtesting
 
 #### `POST /api/trading/backtest`
@@ -1012,6 +1174,7 @@ Launch a backtest run asynchronously.
 #### `GET /api/trading/backtest/{backtest_id}`
 Retrieve backtest results.
 
+- **Path params:** `backtest_id` (UUID string)
 - **Response:** `{ id, start_date, end_date, initial_capital, risk_tier, config, total_return, sharpe_ratio, max_drawdown, win_rate, profit_factor, trade_count, equity_curve[], trades[], status, completed_at, created_at }`
 - Status values: `running`, `completed`, `not_found`, `pending`
 
@@ -1037,10 +1200,11 @@ Update notification preferences.
 
 All fields optional.
 
+- **Response:** `{ updated: { ...changed fields } }`
 - **Errors:** `503` — Engine not initialised
 
 #### `GET /api/trading/notifications/history`
-Return recent notifications.
+Return recent notifications (placeholder — currently returns empty array).
 
 | Parameter | Type | Default | Constraints | Description |
 |-----------|------|---------|-------------|-------------|
@@ -1116,6 +1280,8 @@ List pending approval requests.
 #### `GET /approvals/{approval_id}`
 Get a single approval request.
 
+- **Path params:** `approval_id` (UUID string)
+- **Response:** Approval request object
 - **Errors:** `404` — Approval not found; `503` — Database not ready
 
 #### `POST /approvals/{approval_id}/review`
@@ -1138,4 +1304,4 @@ Approve or reject a pending approval request.
 Expire stale approvals that have passed their expiration time.
 
 - **Response:** `{ expired: int, items: [] }`
-- **Errors:** `503` — Database not ready
+- **Errors:** `503` — Database not ready