docs(handoff): exp24 complete, exp25 running with wheel fix

exp24 final: 19/19 full episodes, best 365.5r@170k, 3-road mean 346.5r.
exp25 launched on patched sim (wheel OverlapSphere), log file confirmed writing.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agent/SESSION_HANDOFF.md

@@ -137,20 +137,20 @@ to Unity physics non-determinism, NOT road variety.
 - Rsync'd to: `/mnt/c/Users/Paul/Downloads/DonkeySimWin/DonkeySimWin/`
 - Sim restarted on port 9091 with new binary
 
-### Exp 24 status — RUNNING (~100 min remaining as of 20:22)
-- PID 733053, launched at 20:09 on 2026-05-05
-- Monitor: `tail -f /tmp/exp24.out`
-- Results so far: 10k→250.4r/2000s ✅, 20k→320.9r/2000s ✅ (NEW BEST both times)
-- NOTE: log file is 0 bytes (logging.basicConfig no-op). All output in /tmp/exp24.out.
-- Auto-transition to exp25 is armed — when exp24 finishes, monitor kills sim, restarts
-  with wheel-fix binary, and launches exp25 automatically.
+### Exp 24 status — COMPLETE
+- Finished at 22:03 on 2026-05-05
+- 19 consecutive full episodes (2000 steps each), zero crashes during training
+- Best checkpoint: 170k → 365.5r / 2000s ✅
+- Full eval curve: 250→320→333→327→323→344→352→346→340→334→347→355→356→345→363→353→365→354→354→354
+- Final 3-road eval (best_model): Set1=305r/1680s❌, Set2=368r/2000s✅, Set3=365r/2000s✅
+  Mean: 1893 steps / 346.5 reward
+- Log: `/tmp/exp24.out` (log file was 0 bytes — logging.basicConfig no-op fixed in exp25)
 
-### Exp 25 status — PENDING
-- Script: `agent/experiments/exp25_wheel_collision_fix.py`
-- Model dir: `agent/models/exp25-wheel-fix/`
-- Monitor: `tail -f /tmp/exp25.out` (once launched)
-- Key fix: per-wheel OverlapSphere in Car.cs catches any-angle barrier contact
-- Binary: already rsync'd, sim restart needed (auto-transition handles this)
+### Exp 25 status — RUNNING
+- PID 776352, launched at 22:12 on 2026-05-05
+- Log: `agent/models/exp25-wheel-fix/run_2026-05-05_221255_wheel_fix.log` ← writes correctly!
+- Monitor: `tail -f agent/models/exp25-wheel-fix/run_2026-05-05_221255_wheel_fix.log`
+- Running on patched sim with wheel OverlapSphere fix (any-angle barrier detection)
 
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