critical: Fix distributed worker quality_filter - dict to lambda function

Root cause: Passing dict {'min_adx': 15, 'min_volume_ratio': vol_min} when
simulate_money_line() expects callable function.

Bug caused ALL 2,096 backtests to fail with 'dict' object is not callable.

Fix: Changed to lambda function matching comprehensive_sweep.py pattern:
  quality_filter = lambda s: s.adx >= 15 and s.volume_ratio >= vol_min

Verified fix working: Workers running at 100% CPU, no errors after 2+ minutes.

cluster/CRITICAL_BUG_FIX_DEC1_2025.md

@@ -0,0 +1,144 @@
+# CRITICAL BUG FIX - Distributed Worker Quality Filter (Dec 1, 2025)
+
+## 🔥 Critical Bug Discovered
+
+**Date:** December 1, 2025, 14:40 UTC
+**Impact:** ALL 2,096 backtests failed with `'dict' object is not callable` error
+**Severity:** CRITICAL - Blocked all distributed work
+
+## Symptom
+
+All parameter combinations tested returned 0 trades:
+- Chunk 0: 2,000 configs, all with `trades=0`
+- Chunk 2: 96 configs, all with `trades=0`
+- Worker logs showed: `Error testing config X: 'dict' object is not callable` (repeated 2,096 times)
+
+## Root Cause
+
+**File:** `cluster/distributed_worker.py`
+**Lines:** 67-70
+
+**BROKEN CODE:**
+```python
+# Quality filter (matches comprehensive_sweep.py)
+quality_filter = {
+    'min_adx': 15,
+    'min_volume_ratio': vol_min,
+}
+```
+
+**Problem:** Passing a `dict` object when `simulate_money_line()` expects a **callable function**.
+
+## Investigation Timeline
+
+1. **14:35** - User reported "something finished"
+2. **14:40** - Discovered all 2,096 results had 0 trades
+3. **14:45** - Found error in worker logs: `'dict' object is not callable`
+4. **14:50** - Compared to `comprehensive_sweep.py` (working version)
+5. **14:52** - **ROOT CAUSE IDENTIFIED**: dict vs lambda function
+6. **14:55** - Fix applied and deployed
+7. **15:00** - Fix verified working (workers at 100% CPU, no errors)
+
+## The Fix
+
+**BEFORE (BROKEN):**
+```python
+quality_filter = {
+    'min_adx': 15,
+    'min_volume_ratio': vol_min,
+}
+```
+
+**AFTER (FIXED):**
+```python
+# CRITICAL FIX (Dec 1, 2025): Must be lambda function, not dict!
+# Bug was passing dict which caused "'dict' object is not callable" error
+if vol_min > 0:
+    quality_filter = lambda s: s.adx >= 15 and s.volume_ratio >= vol_min
+else:
+    quality_filter = None
+```
+
+## Why It Broke
+
+In `backtester/simulator.py` (line 118):
+```python
+if not quality_filter(signal):
+    continue
+```
+
+The code calls `quality_filter()` as a **function**. When we passed a dict, Python tried to call a dict object, causing `'dict' object is not callable`.
+
+## How It Was Missed
+
+- Coordinator and worker infrastructure all worked correctly
+- Data loaded successfully (34,273 rows)
+- Multiprocessing started without errors
+- Worker's exception handler caught the error and returned zeros
+- **Silent failure:** No crash, just invalid results
+- Files created looked successful (183KB)
+
+## Verification Steps
+
+1. ✅ Deployed fixed code to worker1
+2. ✅ Cleaned up invalid results and database
+3. ✅ Restarted coordinator with fixed worker
+4. ✅ Verified no `'dict' object is not callable` errors in logs
+5. ✅ Confirmed 24 Python processes running at 100% CPU
+6. ✅ Workers actively computing (no immediate errors for 2+ minutes)
+
+## Lessons Learned
+
+1. **Type matters:** Dict vs callable - subtle but critical difference
+2. **Silent failures are dangerous:** Exception handler hid the severity
+3. **Compare to working code:** `comprehensive_sweep.py` had correct pattern
+4. **Verify results quality:** All zeros = red flag, investigate immediately
+5. **Test fixes locally first:** Would have caught this earlier
+6. **Add validation:** Should detect all-zero results and abort
+
+## Files Changed
+
+- `cluster/distributed_worker.py` - Fixed quality_filter (dict → lambda)
+
+## Commit
+
+```bash
+git add cluster/distributed_worker.py cluster/CRITICAL_BUG_FIX_DEC1_2025.md
+git commit -m "critical: Fix distributed worker quality_filter - dict to lambda function
+
+Root cause: Passing dict {'min_adx': 15, 'min_volume_ratio': vol_min} when
+simulate_money_line() expects callable function.
+
+Bug caused ALL 2,096 backtests to fail with 'dict' object is not callable.
+
+Fix: Changed to lambda function matching comprehensive_sweep.py pattern:
+  quality_filter = lambda s: s.adx >= 15 and s.volume_ratio >= vol_min
+
+Verified fix working: Workers running at 100% CPU, no errors after 2+ minutes.
+"
+git push
+```
+
+## Status
+
+- ✅ Bug identified and fixed
+- ✅ Code deployed to worker1
+- ✅ Coordinator restarted
+- ✅ Workers actively processing (100% CPU, no errors)
+- ⏳ Awaiting completion of chunk 0 (2,000 configs, ~22 minutes estimated)
+- ⏳ Full sweep restart: 4,096 configs total
+
+## Expected Timeline
+
+- **Chunk 0:** ~22 minutes (2,000 configs)
+- **Chunk 1:** ~22 minutes (2,000 configs) 
+- **Chunk 2:** ~1 minute (96 configs)
+- **Total:** ~45 minutes for complete sweep
+
+## Next Steps
+
+1. Monitor chunk 0 completion (~10 minutes remaining)
+2. Verify results have trades > 0 (not all zeros)
+3. Import successful results to database
+4. Analyze top performers
+5. Deploy to worker2 for parallel processing

cluster/distributed_worker.py

@@ -63,11 +63,13 @@ def test_config(args):
         max_bars_per_trade=max_bars,
     )
     
-    # Quality filter (matches comprehensive_sweep.py)
-    quality_filter = {
-        'min_adx': 15,
-        'min_volume_ratio': vol_min,
-    }
+    # Quality filter (matches comprehensive_sweep.py signature)
+    # CRITICAL FIX (Dec 1, 2025): Must be lambda function, not dict!
+    # Bug was passing dict which caused "'dict' object is not callable" error
+    if vol_min > 0:
+        quality_filter = lambda s: s.adx >= 15 and s.volume_ratio >= vol_min
+    else:
+        quality_filter = None
     
     # Run simulation
     try: