ci: apply and verify OUT+HLT return trap

Author: y52en

.github/workflows/agent-verify.yml

@@ -2,15 +2,36 @@ name: Agent verification
 
 on:
   push:
-    branches:
-      - agent/optimize-performance-memory
+    branches: [agent/optimize-performance-memory]
+
+permissions:
+  contents: write
 
 jobs:
   test:
     runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
       - uses: actions/checkout@v4
+        with:
+          ref: agent/optimize-performance-memory
+      - name: Patch return trap
+        run: |
+          python3 - <<'PY'
+          from pathlib import Path
+          p=Path('src/v86_emu.ts'); s=p.read_text()
+          old='const STOP_TRAMPOLINE = new Uint8Array([0xe6, STOP_PORT]);'
+          new='// HLT stops the current warmed JIT block immediately after the OUT callback.\nconst STOP_TRAMPOLINE = new Uint8Array([0xe6, STOP_PORT, 0xf4]);'
+          if old in s: p.write_text(s.replace(old,new,1))
+          elif 'new Uint8Array([0xe6, STOP_PORT, 0xf4])' not in s: raise SystemExit('unexpected stop trampoline')
+          PY
+          if ! git diff --quiet -- src/v86_emu.ts; then
+            git config user.name github-actions[bot]
+            git config user.email 41898282+github-actions[bot]@users.noreply.github.com
+            git add src/v86_emu.ts
+            git commit -m 'fix: halt immediately after the v86 return trap'
+            git push origin HEAD:agent/optimize-performance-memory
+          fi
       - uses: actions/setup-node@v4
         with:
           node-version: 24