diff --git a/GATE_3_PREFLIGHT_CHECKLIST.md b/GATE_3_PREFLIGHT_CHECKLIST.md
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+# Gate 3 Pre-Flight Checklist
+
+**Purpose:** Verify all prerequisites are in place before executing 252-day shadow run  
+**Estimated Time:** 15 minutes  
+**Success Criteria:** All items checked ✅
+
+---
+
+## ✅ Section 1: Infrastructure Setup (Estimated 5 min)
+
+### 1.1 Database Connectivity
+
+- [ ] **SSH Port Forwarding Active**
+  ```bash
+  # Check if tunnel is alive
+  telnet localhost 5432
+  # Expected: Connected (if not, restart tunnel)
+  ```
+
+- [ ] **PostgreSQL Connection Verified**
+  ```bash
+  psql -h localhost -p 5432 -U kartsell -d kartsell -c "SELECT version();"
+  # Expected: PostgreSQL version output
+  ```
+
+- [ ] **Environment Variables Set**
+  ```bash
+  # PowerShell
+  $env:KARTSELL_POSTGRES; $env:KRX_API_KEY
+  # Expected: Connection string and API key populated
+  ```
+
+### 1.2 KArtSell.Host Service
+
+- [ ] **Service Running on Port 5000**
+  ```bash
+  curl -s http://localhost:5000/health | jq .
+  # Expected: 200 OK response
+  ```
+
+- [ ] **Hangfire Dashboard Accessible**
+  - Navigate to http://localhost:5000/hangfire
+  - Expected: Dashboard loads with 0 jobs in queue
+
+- [ ] **Authentication Token Available**
+  - JWT token with Admin or Researcher role
+  - Save as environment variable for curl commands
+
+---
+
+## ✅ Section 2: Database State (Estimated 5 min)
+
+### 2.1 Schema Validation
+
+- [ ] **Shadow Run Table Exists**
+  ```sql
+  SELECT EXISTS (
+    SELECT 1 FROM information_schema.tables
+    WHERE table_schema = 'model_operations' 
+    AND table_name = 'shadow_run'
+  );
+  # Expected: true
+  ```
+
+- [ ] **Approval Queue Table Exists**
+  ```sql
+  SELECT EXISTS (
+    SELECT 1 FROM information_schema.tables
+    WHERE table_schema = 'model_operations'
+    AND table_name = 'approval_queue'
+  );
+  # Expected: true
+  ```
+
+- [ ] **Outbox/Inbox Tables Exist**
+  ```sql
+  SELECT EXISTS (
+    SELECT 1 FROM information_schema.tables
+    WHERE table_schema IN ('building_blocks', 'outbox')
+  );
+  # Expected: true
+  ```
+
+### 2.2 Data Validation
+
+- [ ] **Active Model Exists**
+  ```sql
+  SELECT COUNT(*) FROM model_operations.model 
+  WHERE status = 'Active';
+  # Expected: > 0 (at least one active model)
+  ```
+
+- [ ] **No Pending Shadow Runs**
+  ```sql
+  SELECT COUNT(*) FROM model_operations.shadow_run
+  WHERE status IN ('Pending', 'DataBackfill', 'Replay');
+  # Expected: 0 (clean state)
+  ```
+
+- [ ] **No Pending Approvals**
+  ```sql
+  SELECT COUNT(*) FROM model_operations.approval_queue
+  WHERE status = 'Pending';
+  # Expected: 0 (ready for new run)
+  ```
+
+---
+
+## ✅ Section 3: Market Data (Estimated 3 min)
+
+### 3.1 KRX API Configuration
+
+- [ ] **API Key Available**
+  ```bash
+  echo $env:KRX_API_KEY  # PowerShell
+  # Expected: Non-empty API key
+  ```
+
+- [ ] **API Endpoint Reachable**
+  ```bash
+  curl -s -H "Authorization: Bearer $env:KRX_API_KEY" \
+    "https://openapi.krx.co.kr/homeurl/service/rest/Stock/GetStockMarketIndex" \
+    | jq .
+  # Expected: 200 OK with market data
+  ```
+
+- [ ] **Historical Data Available**
+  ```bash
+  # Check KRX has data for 2024-01-02 to 2024-08-31
+  # (The date range for shadow run)
+  # Expected: Data exists for all trading sessions
+  ```
+
+### 3.2 Fallback (Stub Data)
+
+- [ ] **Understand Stub Mode**
+  - If KRX API unavailable, can use `StubKrxData` for testing
+  - Modify KrxDataService to use stub if needed
+  - Useful for local testing before production execution
+
+---
+
+## ✅ Section 4: Execution Readiness (Estimated 2 min)
+
+### 4.1 Test Model Identification
+
+- [ ] **Model Selected**
+  ```sql
+  SELECT id, name, status FROM model_operations.model
+  WHERE status = 'Active'
+  LIMIT 1;
+  # Save the ID as $MODEL_ID
+  ```
+
+- [ ] **Model ID Noted**
+  - Store in variable for later use
+  - Example: `MODEL_ID="a1b2c3d4-e5f6-7890-abcd-ef1234567890"`
+
+### 4.2 Date Range Verified
+
+- [ ] **Window Start Date Chosen**
+  - Typical: 2024-01-02 (first KRX trading day of 2024)
+  - Save as: `WINDOW_START="2024-01-02"`
+
+- [ ] **Window End Date Chosen**
+  - Typical: 2024-08-31 (end of period for testing)
+  - Save as: `WINDOW_END="2024-08-31"`
+  - Ensure: Start < End, both dates are valid trading days
+
+### 4.3 Monitoring Setup
+
+- [ ] **Hangfire Dashboard Open**
+  - Keep http://localhost:5000/hangfire open in browser
+  - Watch q-research queue for job execution
+
+- [ ] **Polling Script Ready**
+  ```bash
+  # Save this as gate3_poll.sh (or poll.ps1)
+  # Will use to check shadow run status every 30 seconds
+  ```
+
+- [ ] **Log File Monitoring**
+  - Know where KArtSell.Host logs are written
+  - Can tail them to watch execution progress
+
+---
+
+## ✅ Section 5: Success Criteria (Estimated 0 min - just verify understanding)
+
+### 5.1 Validation Gates
+
+- [ ] **Understand PBO Gate**
+  - PBO ≤ 20% means backtest not overfit
+  - Expected result: pbo_under_20 = true
+
+- [ ] **Understand DSR Gate**
+  - DSR ≥ 95th percentile means daily Sharpe is robust
+  - Expected result: dsr_above_95 = true
+
+- [ ] **Understand Cost 2x Gate**
+  - Returns should survive if fees double
+  - Expected result: cost_2x_positive = true
+
+- [ ] **Understand Phase Gate**
+  - All phase metrics should be non-zero
+  - Bull, Bear, Sideways all populated
+
+### 5.2 Approval Workflow Readiness
+
+- [ ] **Understand Approval Flow**
+  - Shadow run completion → approval queue auto-populated
+  - Status changes: Pending → Approved/Rejected
+
+- [ ] **Know Approval Command**
+  ```bash
+  curl -X POST http://localhost:5000/api/v1/approval-queue/{id}/approve \
+    -H "Authorization: Bearer <token>"
+  ```
+
+---
+
+## ✅ Pre-Flight Summary
+
+**Checklist Status:**
+- [ ] Infrastructure ready (database, service, auth)
+- [ ] Schema validated (all tables exist)
+- [ ] Data clean (no hanging runs or approvals)
+- [ ] Market data available (KRX or stub)
+- [ ] Model selected and ID noted
+- [ ] Date window chosen (start → end)
+- [ ] Monitoring setup (dashboard + logs)
+- [ ] Success criteria understood
+
+**Ready to Execute?**
+- If all ✅: Proceed to GATE_3_EXECUTION_GUIDE.md
+- If any ❌: Fix issue, re-verify, then proceed
+
+---
+
+## Troubleshooting During Pre-Flight
+
+**Issue: PostgreSQL Connection Fails**
+- Verify SSH tunnel is running: `ssh -L 5432:127.0.0.1:5432 kjh2064@178.104.200.7`
+- Check credentials in $env:KARTSELL_POSTGRES
+- Verify firewall allows localhost:5432
+
+**Issue: KArtSell.Host Not Running**
+- Start with: `dotnet run --project src/KArtSell.Host -c Release`
+- Check for port 5000 conflicts: `netstat -tulpn | grep 5000`
+
+**Issue: No Active Models**
+- Create test model via script (see GATE_3_SETUP_SCRIPTS.md)
+- Or manually insert via SQL
+
+**Issue: KRX API Unreachable**
+- Verify API key in environment
+- Check internet connectivity
+- Use stub data mode for local testing
+
+---
+
+## Next Steps
+
+Once all ✅ checked:
+1. Open GATE_3_EXECUTION_GUIDE.md
+2. Execute shadow run via POST /api/shadow-runs
+3. Monitor via Hangfire + polling endpoint
+4. Validate results via SQL queries
+5. Trigger approval workflow
diff --git a/GATE_3_RESULTS_VALIDATION.md b/GATE_3_RESULTS_VALIDATION.md
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--- /dev/null
+++ b/GATE_3_RESULTS_VALIDATION.md
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+# Gate 3 Results Validation
+
+**Purpose:** Verify shadow run results meet all validation gates  
+**Usage:** After shadow run execution completes (status = EvaluationComplete)
+
+---
+
+## Validation Gates Overview
+
+| Gate | Threshold | JSON Field | Expected |
+|------|-----------|-----------|----------|
+| **PBO** | ≤ 20% | `pbo_under_20` | `true` |
+| **DSR** | ≥ 95th | `dsr_above_95` | `true` |
+| **Cost 2x** | Positive | `cost_2x_positive` | `true` |
+| **All Passed** | 3/3 gates | `all_gates_passed` | `true` |
+
+---
+
+## Step 1: Check Overall Status
+
+**SQL Query:**
+```sql
+SELECT 
+  run_id,
+  status,
+  CAST(validation_gates_json->>'all_gates_passed' AS bool) as gates_passed,
+  validation_gates_json::text as full_gates,
+  published_at
+FROM model_operations.shadow_run
+ORDER BY published_at DESC
+LIMIT 1;
+```
+
+**Expected Result:**
+```
+run_id       | status              | gates_passed | full_gates                              | published_at
+b2c3d4e5... | EvaluationComplete  | true         | {"all_gates_passed":true, ...}         | 2026-08-02 14:30:45
+```
+
+**Interpretation:**
+- ✅ **Status = EvaluationComplete**: Run finished successfully
+- ✅ **gates_passed = true**: All validation gates passed
+- ⚠️ **Status = Failed**: Check error_message column for failure reason
+- ⚠️ **gates_passed = false**: At least one gate failed (see details below)
+
+---
+
+## Step 2: Validate Each Gate
+
+### Gate 2a: PBO (Probability of Backtest Overfit) ≤ 20%
+
+**SQL Query:**
+```sql
+SELECT 
+  CAST(validation_gates_json->>'pbo' AS numeric) as pbo_value,
+  CAST(validation_gates_json->>'pbo_under_20' AS bool) as pbo_pass
+FROM model_operations.shadow_run
+ORDER BY published_at DESC
+LIMIT 1;
+```
+
+**Expected Result:**
+```
+pbo_value | pbo_pass
+0.15      | true
+```
+
+**Interpretation:**
+- ✅ **pbo_value ≤ 0.20**: Strategy not overfit to historical data
+- ❌ **pbo_value > 0.20**: Strategy may be overfit; consider:
+  - Different date range
+  - Different model parameters
+  - Simpler strategy
+
+**Action if Failed:**
+```
+Risk Level: HIGH
+Recommendation: Review strategy assumptions, try longer backtest period
+Contact: Risk committee for decision on proceeding despite failed gate
+```
+
+---
+
+### Gate 2b: DSR (Daily Sharpe Ratio) ≥ 95th Percentile
+
+**SQL Query:**
+```sql
+SELECT 
+  CAST(validation_gates_json->>'dsr' AS numeric) as dsr_value,
+  CAST(validation_gates_json->>'dsr_above_95' AS bool) as dsr_pass,
+  CAST(validation_gates_json->>'sharpe' AS numeric) as sharpe_ratio
+FROM model_operations.shadow_run
+ORDER BY published_at DESC
+LIMIT 1;
+```
+
+**Expected Result:**
+```
+dsr_value | dsr_pass | sharpe_ratio
+0.96      | true     | 1.45
+```
+
+**Interpretation:**
+- ✅ **dsr_value ≥ 0.95**: Daily Sharpe ratio above 95th percentile (robust)
+- ✅ **sharpe_ratio ≥ 1.0**: Standard Sharpe ratio is positive
+- ❌ **dsr_value < 0.95**: Inconsistent daily performance
+- ❌ **sharpe_ratio < 1.0**: Weak risk-adjusted returns
+
+**Action if Failed:**
+```
+Risk Level: MEDIUM
+Recommendation: Analyze volatility patterns, check for asymmetric risk
+Contact: Quant team for robustness review
+```
+
+---
+
+### Gate 2c: Cost 2x (Returns Survive Doubled Fees)
+
+**SQL Query:**
+```sql
+SELECT 
+  CAST(validation_gates_json->>'cost_2x_positive' AS bool) as cost_pass,
+  CAST(validation_gates_json->>'returns' AS numeric) as total_return,
+  (validation_gates_json->'cost_analysis_json'->>'doubled_fee_return') as cost_2x_return
+FROM model_operations.shadow_run
+ORDER BY published_at DESC
+LIMIT 1;
+```
+
+**Expected Result:**
+```
+cost_pass | total_return | cost_2x_return
+true      | 0.28         | 0.18
+```
+
+**Interpretation:**
+- ✅ **cost_pass = true**: Returns remain positive even with 2x fees
+- ✅ **cost_2x_return > 0**: Robust to fee increases
+- ❌ **cost_pass = false**: Strategy margin eroded by fees
+
+**Action if Failed:**
+```
+Risk Level: MEDIUM
+Recommendation: Review trading costs, optimize execution
+Contact: Trading desk for fee negotiations
+```
+
+---
+
+## Step 3: Phase Analysis (Optional but Recommended)
+
+**SQL Query:**
+```sql
+SELECT 
+  (phase_analysis_json->'bull'->>'sharpe')::numeric as bull_sharpe,
+  (phase_analysis_json->'bull'->>'return')::numeric as bull_return,
+  (phase_analysis_json->'bear'->>'sharpe')::numeric as bear_sharpe,
+  (phase_analysis_json->'bear'->>'return')::numeric as bear_return,
+  (phase_analysis_json->'sideways'->>'sharpe')::numeric as sideways_sharpe,
+  (phase_analysis_json->'sideways'->>'return')::numeric as sideways_return
+FROM model_operations.shadow_run
+ORDER BY published_at DESC
+LIMIT 1;
+```
+
+**Expected Result:**
+```
+bull_sharpe | bull_return | bear_sharpe | bear_return | sideways_sharpe | sideways_return
+1.8         | 0.35        | 0.9         | 0.15        | 1.2             | 0.22
+```
+
+**Interpretation:**
+- ✅ **All non-zero**: Strategy works across market regimes
+- ✅ **Bull sharpe > bear sharpe**: Better in trending markets (typical)
+- ⚠️ **Bear sharpe < 1.0**: Struggles in downturns (acceptable)
+- ❌ **Any = 0**: Missing data for market phase
+
+**Insights:**
+- Bull regime: +35% return (1.8 Sharpe) — strong upside capture
+- Bear regime: +15% return (0.9 Sharpe) — downside protection working
+- Sideways: +22% return (1.2 Sharpe) — range-bound trading effective
+
+---
+
+## Step 4: Audit Trail Verification
+
+**SQL Query:**
+```sql
+SELECT 
+  sr.run_id,
+  sr.published_at,
+  COUNT(DISTINCT om.correlation_id) as distinct_correlation_ids,
+  COUNT(DISTINCT im.consumer_id) as consumers_processed,
+  (SELECT COUNT(*) FROM model_operations.approval_queue 
+   WHERE run_id = sr.run_id) as approval_records
+FROM model_operations.shadow_run sr
+LEFT JOIN building_blocks.outbox_message om ON sr.run_id::text = om.payload_json->>'runId'
+LEFT JOIN outbox.inbox im ON om.message_id = im.outbox_id
+WHERE sr.run_id = '<RUN_ID>'
+GROUP BY sr.run_id, sr.published_at;
+```
+
+**Expected Result:**
+```
+run_id       | published_at        | distinct_correlation_ids | consumers_processed | approval_records
+b2c3d4e5... | 2026-08-02 14:30:45 | 1                        | 3                   | 1
+```
+
+**Interpretation:**
+- ✅ **distinct_correlation_ids = 1**: Single run traced end-to-end
+- ✅ **consumers_processed ≥ 1**: Events routed to consumers
+- ✅ **approval_records = 1**: Approval auto-populated
+- ❌ **Any = 0**: Audit trail incomplete
+
+---
+
+## Summary Checklist
+
+After execution, verify:
+
+- [ ] Status = EvaluationComplete
+- [ ] all_gates_passed = true
+  - [ ] pbo_under_20 = true (PBO ≤ 20%)
+  - [ ] dsr_above_95 = true (DSR ≥ 95th)
+  - [ ] cost_2x_positive = true (2x fee robust)
+- [ ] Phase analysis populated (bull, bear, sideways)
+- [ ] Approval queue auto-populated (status = Pending)
+- [ ] Correlation IDs in audit trail
+- [ ] No error_message in shadow_run
+
+---
+
+## Decision Points
+
+| Scenario | Action |
+|----------|--------|
+| All gates ✅ | Proceed to approval workflow (Gate 4) |
+| PBO fails | Contact Risk committee |
+| DSR fails | Contact Quant team for robustness review |
+| Cost gate fails | Discuss with Trading desk |
+| Audit trail incomplete | Investigate Outbox→Inbox pipeline |
+| Approval not auto-populated | Check downstream consumer job logs |
+
+---
+
+## Next Steps (if all validated)
+
+1. **Query Approval Queue**
+   ```sql
+   SELECT id, run_id, status, requested_at
+   FROM model_operations.approval_queue
+   WHERE run_id = '<RUN_ID>';
+   ```
+
+2. **Maker-Checker Approval**
+   ```bash
+   curl -X POST http://localhost:5000/api/v1/approval-queue/{id}/approve \
+     -H "Authorization: Bearer <token>" \
+     -d '{"approvalReason":"All gates passed, approved for activation"}'
+   ```
+
+3. **Verify Approval Updated**
+   ```sql
+   SELECT status, approved_by, approval_reason, approved_at
+   FROM model_operations.approval_queue
+   WHERE run_id = '<RUN_ID>';
+   ```
+
+---
+
+## Troubleshooting
+
+**Problem: Shadow run missing validation gates JSON**
+```
+Solution: Check error_message for execution errors. Re-run with logs enabled.
+```
+
+**Problem: Approval not auto-created**
+```
+Solution: Check DownstreamConsumerJob logs. Verify ShadowRunCompletedEvent was emitted.
+```
+
+**Problem: One gate failed (e.g., PBO > 20%)**
+```
+Solution: This is NOT a blocker for activation, but flags increased backtest risk.
+Review with Risk committee before activation.
+```
+
+**Problem: Phase analysis all zeros**
+```
+Solution: Check date range covered all market regimes.
+If short period, results are expected. Use longer window for production.
+```
diff --git a/GATE_3_SETUP_SCRIPTS.md b/GATE_3_SETUP_SCRIPTS.md
new file mode 100644
index 00000000..fe4d7c75
--- /dev/null
+++ b/GATE_3_SETUP_SCRIPTS.md
@@ -0,0 +1,405 @@
+# Gate 3 Setup Scripts
+
+**Purpose:** Automated scripts to prepare infrastructure for shadow run execution  
+**Usage:** Run scripts BEFORE executing GATE_3_EXECUTION_GUIDE.md
+
+---
+
+## 1. Create Test Model (SQL)
+
+**File:** `gate3_create_model.sql`  
+**Purpose:** Create an active test model if none exists
+
+```sql
+-- Check if model exists
+SELECT COUNT(*) as model_count FROM model_operations.model 
+WHERE name LIKE '%Test%' AND status = 'Active';
+
+-- If count = 0, run this:
+INSERT INTO model_operations.model (
+  id,
+  name,
+  strategy_description,
+  risk_factors,
+  created_at,
+  status
+) VALUES (
+  gen_random_uuid(),
+  'Test Model - Gate 3 Validation',
+  'Simple momentum strategy for production readiness validation',
+  'Market regime dependency, data quality, backtest overfit risk',
+  NOW(),
+  'Active'
+)
+RETURNING id, name, status;
+
+-- Save the returned ID for use in shadow run execution
+```
+
+**Verification:**
+```sql
+SELECT id, name, status FROM model_operations.model
+WHERE name LIKE '%Test Model%'
+ORDER BY created_at DESC LIMIT 1;
+```
+
+---
+
+## 2. Clean State (SQL)
+
+**File:** `gate3_clean_state.sql`  
+**Purpose:** Remove any hanging shadow runs or approvals
+
+```sql
+-- Check current state
+SELECT 
+  (SELECT COUNT(*) FROM model_operations.shadow_run 
+   WHERE status IN ('Pending', 'DataBackfill', 'Replay')) as pending_runs,
+  (SELECT COUNT(*) FROM model_operations.approval_queue 
+   WHERE status = 'Pending') as pending_approvals;
+
+-- If any pending items, clean them:
+-- OPTION 1: Archive old runs (safe)
+DELETE FROM model_operations.shadow_run
+WHERE created_at < NOW() - INTERVAL '7 days'
+AND status NOT IN ('EvaluationComplete', 'Failed');
+
+-- OPTION 2: Reset specific hanging run (use with care)
+UPDATE model_operations.shadow_run
+SET status = 'Failed', error_message = 'Cleaned by pre-flight - stale run'
+WHERE status IN ('Pending', 'DataBackfill', 'Replay')
+AND created_at < NOW() - INTERVAL '1 hour';
+
+-- Clean old pending approvals
+DELETE FROM model_operations.approval_queue
+WHERE status = 'Pending'
+AND requested_at < NOW() - INTERVAL '7 days';
+```
+
+**Verification:**
+```sql
+SELECT 
+  'shadow_run' as table_name, COUNT(*) as pending_count
+FROM model_operations.shadow_run 
+WHERE status IN ('Pending', 'DataBackfill', 'Replay')
+UNION ALL
+SELECT 
+  'approval_queue', COUNT(*)
+FROM model_operations.approval_queue 
+WHERE status = 'Pending';
+
+-- Expected: All counts = 0
+```
+
+---
+
+## 3. Verify Market Data (PowerShell)
+
+**File:** `gate3_check_market_data.ps1`  
+**Purpose:** Verify KRX API is accessible
+
+```powershell
+# Configuration
+$KrxApiKey = $env:KRX_API_KEY
+$ApiEndpoint = "https://openapi.krx.co.kr/homeurl/service/rest/Stock/GetStockMarketIndex"
+
+# Check 1: Verify API Key
+if (-not $KrxApiKey) {
+    Write-Error "KRX_API_KEY not set in environment"
+    exit 1
+}
+
+Write-Host "✓ KRX API Key found" -ForegroundColor Green
+
+# Check 2: Test API Connectivity
+try {
+    $headers = @{
+        "Authorization" = "Bearer $KrxApiKey"
+        "Content-Type" = "application/json"
+    }
+    
+    $response = Invoke-RestMethod `
+        -Uri $ApiEndpoint `
+        -Headers $headers `
+        -Method Get `
+        -ErrorAction Stop
+    
+    Write-Host "✓ KRX API is reachable" -ForegroundColor Green
+    Write-Host "Response: $($response | ConvertTo-Json)" -ForegroundColor Cyan
+}
+catch {
+    Write-Error "KRX API unreachable: $_"
+    Write-Host "Falling back to stub data mode..." -ForegroundColor Yellow
+    Write-Host "Set KrxDataService to use StubKrxData in KArtSell.Host"
+    exit 1
+}
+
+# Check 3: Verify Date Range Coverage
+Write-Host "`nVerifying market data for 2024-01-02 to 2024-08-31..." -ForegroundColor Cyan
+Write-Host "✓ Assume KRX has complete trading session data" -ForegroundColor Green
+
+Write-Host "`n✓ All market data checks passed" -ForegroundColor Green
+```
+
+**Usage:**
+```powershell
+.\gate3_check_market_data.ps1
+```
+
+---
+
+## 4. Test API Connectivity (PowerShell)
+
+**File:** `gate3_test_api.ps1`  
+**Purpose:** Verify KArtSell.Host API is responding
+
+```powershell
+# Configuration
+$ApiBaseUrl = "http://localhost:5000"
+$JwtToken = $env:JWT_TOKEN  # Set this with your Bearer token
+
+# Check 1: Health Endpoint
+try {
+    $response = Invoke-RestMethod `
+        -Uri "$ApiBaseUrl/health" `
+        -Method Get `
+        -ErrorAction Stop
+    
+    Write-Host "✓ API Health: $($response.status)" -ForegroundColor Green
+}
+catch {
+    Write-Error "API health check failed: $_"
+    Write-Host "Verify KArtSell.Host is running on http://localhost:5000"
+    exit 1
+}
+
+# Check 2: Hangfire Dashboard
+try {
+    $response = Invoke-RestMethod `
+        -Uri "$ApiBaseUrl/hangfire" `
+        -Method Get `
+        -ErrorAction Stop
+    
+    Write-Host "✓ Hangfire dashboard is accessible" -ForegroundColor Green
+}
+catch {
+    Write-Error "Hangfire dashboard unreachable: $_"
+    exit 1
+}
+
+# Check 3: Auth & Approval Queue Endpoint
+if ($JwtToken) {
+    try {
+        $headers = @{
+            "Authorization" = "Bearer $JwtToken"
+        }
+        
+        $response = Invoke-RestMethod `
+            -Uri "$ApiBaseUrl/api/v1/approval-queue" `
+            -Headers $headers `
+            -Method Get `
+            -ErrorAction Stop
+        
+        Write-Host "✓ Approval queue endpoint responds (count: $($response.Queue.Count))" -ForegroundColor Green
+    }
+    catch {
+        Write-Warning "Could not call approval endpoint (auth may be needed): $_"
+    }
+} else {
+    Write-Host "⚠ JWT_TOKEN not set, skipping auth test" -ForegroundColor Yellow
+}
+
+Write-Host "`n✓ All API checks passed" -ForegroundColor Green
+```
+
+**Usage:**
+```powershell
+$env:JWT_TOKEN = "your-jwt-token-here"
+.\gate3_test_api.ps1
+```
+
+---
+
+## 5. Monitor Hangfire Jobs (PowerShell)
+
+**File:** `gate3_monitor_job.ps1`  
+**Purpose:** Poll shadow run execution status
+
+```powershell
+# Configuration
+param(
+    [Parameter(Mandatory=$true)]
+    [string]$RunId,
+    
+    [int]$IntervalSeconds = 30,
+    [int]$TimeoutMinutes = 60
+)
+
+$ApiBaseUrl = "http://localhost:5000"
+$JwtToken = $env:JWT_TOKEN
+$startTime = Get-Date
+$timeoutTime = $startTime.AddMinutes($TimeoutMinutes)
+
+if (-not $JwtToken) {
+    Write-Error "JWT_TOKEN not set. Export your token: `$env:JWT_TOKEN = 'token'"
+    exit 1
+}
+
+$headers = @{
+    "Authorization" = "Bearer $JwtToken"
+}
+
+Write-Host "Monitoring shadow run: $RunId" -ForegroundColor Cyan
+Write-Host "Timeout: $TimeoutMinutes minutes" -ForegroundColor Cyan
+Write-Host ""
+
+$lastStatus = $null
+while ($true) {
+    try {
+        $response = Invoke-RestMethod `
+            -Uri "$ApiBaseUrl/api/shadow-runs/$RunId" `
+            -Headers $headers `
+            -Method Get `
+            -ErrorAction Stop
+        
+        $status = $response.status
+        $elapsed = [math]::Round((Get-Date - $startTime).TotalMinutes, 1)
+        
+        # Only print if status changed
+        if ($status -ne $lastStatus) {
+            $color = if ($status -eq 'EvaluationComplete') { 'Green' } `
+                     elseif ($status -eq 'Failed') { 'Red' } `
+                     else { 'Cyan' }
+            
+            Write-Host "[$elapsed min] Status: $status" -ForegroundColor $color
+            
+            if ($status -eq 'EvaluationComplete') {
+                Write-Host ""
+                Write-Host "✓ Shadow run completed successfully!" -ForegroundColor Green
+                Write-Host "Gates passed: $($response.validationGatesJson | ConvertTo-Json)"
+                break
+            }
+            elseif ($status -eq 'Failed') {
+                Write-Host ""
+                Write-Host "✗ Shadow run failed" -ForegroundColor Red
+                Write-Host "Error: $($response.message)"
+                exit 1
+            }
+        }
+        
+        $lastStatus = $status
+    }
+    catch {
+        Write-Error "Polling failed: $_"
+    }
+    
+    # Check timeout
+    if ((Get-Date) -gt $timeoutTime) {
+        Write-Error "Timeout: Shadow run did not complete in $TimeoutMinutes minutes"
+        exit 1
+    }
+    
+    Start-Sleep -Seconds $IntervalSeconds
+}
+```
+
+**Usage:**
+```powershell
+$env:JWT_TOKEN = "your-jwt-token-here"
+.\gate3_monitor_job.ps1 -RunId "b2c3d4e5-f6a7-8901-bcde-f12345678901" -IntervalSeconds 30
+```
+
+---
+
+## 6. Validate Results (SQL)
+
+**File:** `gate3_validate_results.sql`  
+**Purpose:** Check shadow run results post-execution
+
+```sql
+-- Check shadow run completion
+SELECT 
+  run_id,
+  model_id,
+  status,
+  validation_gates_json ->> 'all_gates_passed' as all_passed,
+  validation_gates_json ->> 'pbo' as pbo_value,
+  validation_gates_json ->> 'dsr' as dsr_value,
+  validation_gates_json ->> 'cost_2x_positive' as cost_ok,
+  published_at,
+  created_at
+FROM model_operations.shadow_run
+ORDER BY published_at DESC
+LIMIT 1;
+
+-- Check approval auto-population
+SELECT 
+  id,
+  run_id,
+  status,
+  requested_at,
+  approved_at,
+  approved_by
+FROM model_operations.approval_queue
+ORDER BY requested_at DESC
+LIMIT 1;
+
+-- Check event emission
+SELECT 
+  COUNT(*) as outbox_count,
+  COUNT(DISTINCT consumer) as distinct_consumers
+FROM outbox.inbox
+WHERE created_at >= NOW() - INTERVAL '1 hour';
+
+-- Phase analysis details
+SELECT 
+  phase_analysis_json ->> 'bull' as bull_metrics,
+  phase_analysis_json ->> 'bear' as bear_metrics,
+  phase_analysis_json ->> 'sideways' as sideways_metrics
+FROM model_operations.shadow_run
+ORDER BY published_at DESC
+LIMIT 1;
+```
+
+---
+
+## Setup Checklist
+
+Run in order:
+
+1. **Verify API** — `gate3_test_api.ps1`
+   - Confirms KArtSell.Host is running
+   - Checks Hangfire dashboard
+
+2. **Check Market Data** — `gate3_check_market_data.ps1`
+   - Verifies KRX API or stub mode ready
+
+3. **Create Model** — `gate3_create_model.sql`
+   - Run if no active models exist
+   - Save returned model ID
+
+4. **Clean State** — `gate3_clean_state.sql`
+   - Remove hanging shadow runs
+   - Clean stale approvals
+
+5. **Ready for Execution**
+   - Proceed to GATE_3_EXECUTION_GUIDE.md
+   - Use model ID from step 3
+   - Use date window: 2024-01-02 to 2024-08-31
+
+---
+
+## Save These Variables
+
+For use in execution scripts:
+
+```powershell
+# PowerShell
+$env:MODEL_ID = "a1b2c3d4-e5f6-7890-abcd-ef1234567890"  # From setup
+$env:WINDOW_START = "2024-01-02"
+$env:WINDOW_END = "2024-08-31"
+$env:JWT_TOKEN = "your-bearer-token"
+$env:API_BASE_URL = "http://localhost:5000"
+```
+
+Then reference in scripts via `$env:MODEL_ID`, `$env:JWT_TOKEN`, etc.