# Cross-Code Review Report: B-13 Stage 2 — Runtime Freeze Snapshot

- **Job ID**: 86163ca6
- **Reviewer**: cline
- **Date**: 2026-08-17
- **Scope**: B-13 Stage 2 runtime freeze snapshot in `run_loop.sh`, 5 new regression tests in `tests/test_o3_scoped_guard.py`, and documentation updates in `IMPROVEMENTS.md` and `VERSIONS.md`

---

## 1. Changeset Overview

| File | Lines Changed | Description |
|---|---|---|
| `.agents/skills/multi-agent-mux-loop/scripts/run_loop.sh` | +44/-27 | Freeze snapshot logic, argv capture, `MAM_REAL_ROOT` separation, extended `_mam_release_guard` |
| `tests/test_o3_scoped_guard.py` | +102/-0 | 5 new B-13 regression tests |
| `IMPROVEMENTS.md` | +16/-7 | B-13 moved from open to completed; 271/271 test count |
| `VERSIONS.md` | +9/-0 | New entry #8 for B-13/Stage 2 |
| **Total** | **+174/-31** | 4 files |

---

## 2. Lint Perspective

### 2.1 Bash Syntax (`run_loop.sh`)
- `bash -n run_loop.sh` → **PASS** (no syntax errors)
- `shellcheck` not available on this system; manual review performed

### 2.2 Bash 3.2 Compatibility
- `${MAM_LOOP_ARGV[@]+"${MAM_LOOP_ARGV[@]}"}` (line 108): Valid bash 3.2 guard for expanding potentially empty arrays. Without this guard, bash 3.2 (macOS default) would error on `"${MAM_LOOP_ARGV[@]}"` when the array is empty. **Correct.**

### 2.3 Python Compilation (`test_o3_scoped_guard.py`)
- `py_compile test_o3_scoped_guard.py` → **PASS** (no compile errors)
- All imports (`os`, `json`, `shutil`, `subprocess`, `time`, `Path`, `pytest`) are used; no unused imports introduced

### 2.4 Code Style
- Variable naming (`MAM_LOOP_ARGV`, `MAM_REAL_ROOT`, `MAM_LOOP_FREEZE_DIR`, `MAM_LOOP_FREEZE_OWNED`, `MAM_LOOP_NO_FREEZE`) follows existing `MAM_*` convention
- Comment style matches existing patterns (Korean/English mixed, inline references to bug IDs)
- No trailing whitespace or formatting issues introduced

**Lint Verdict: PASS**

---

## 3. Operability Perspective

### 3.1 Full Test Suite
- **271 passed in 445.76s (0:07:25)** — EXIT_CODE:0
- Previous baseline: 266 tests (job 2f64681f). New total: 266 + 5 B-13 tests = 271. **Consistent.**
- Test count in IMPROVEMENTS.md (271/271) and VERSIONS.md (271/271) matches actual results.

### 3.2 B-13 Regression Tests (5/5 PASS in 0.34s)

| Test | Status | What It Verifies |
|---|---|---|
| `test_b13_reexec_preserves_original_argv` | PASS | Argv forwarded through freeze re-exec (arg parser consumes `$@` via shift) |
| `test_b13_freeze_survives_broken_wrapper` | PASS | Frozen copy immune to wrapper broken mid-loop |
| `test_b13_freeze_dir_is_outside_the_skill_tree` | PASS | No files written under `.agents/skills/` (B-6 boundary) |
| `test_b13_release_guard_cleans_up_and_releases_lock` | PASS | Extended `_mam_release_guard` releases lock + removes snapshot |
| `test_b13_no_freeze_switch_disables_reexec` | PASS | `MAM_LOOP_NO_FREEZE=1` skips freeze entirely |

### 3.3 Existing Test Regression Check
- All 27 pre-existing tests in `test_o3_scoped_guard.py` still pass (32/32 total in file)
- No regressions detected in any test file

### 3.4 Live Freeze Verification
- During this review, the actual `run_loop.sh` orchestrator (PID 88241) was observed running from `/var/folders/.../mam-loop-freeze.L2nD67/.agents/skills/multi-agent-mux-loop/scripts/run_loop.sh` — confirming the freeze mechanism works in production, not just in tests.

### 3.5 Freeze Logic Analysis

**Code path vs. Data path separation:**

| Variable | After Re-exec | Used For | Correct? |
|---|---|---|---|
| `$REPO_ROOT` | Freeze dir (e.g., `/tmp/mam-loop-freeze.XXXXXX`) | Loading scripts (`source`), running wrapper (`delegate_job_safe`) | Yes — code runs from frozen snapshot |
| `$MAM_REAL_ROOT` | Original repo (e.g., `/Users/.../multi-agent-mux`) | Lock marker, `.tmp` cleanup, `git rev-parse`, `mam_collect_changes_diff` | Yes — state/git ops use real repo |

**3 `$REPO_ROOT` → `$MAM_REAL_ROOT` conversions** (lines 175, 488, 580):
- Line 175: `rm -f "$MAM_REAL_ROOT/.agents/skills/..."` — cleans `.tmp` files in real repo (was `$REPO_ROOT`)
- Line 488: `BASE_COMMIT=$(cd -P "$MAM_REAL_ROOT" ...)` — git operations in real repo (was `$REPO_ROOT`)
- Line 580: `mam_collect_changes_diff "$MAM_REAL_ROOT" ...` — diff collection in real repo (was `$REPO_ROOT`)

All remaining `$REPO_ROOT` usages (lines 17, 19, 21, 101, 104-106, 130) are correct — they either load scripts from the freeze dir or export env vars before the re-exec.

**Graceful degradation:**
- If `mktemp -d` fails or `cp -R` fails, the freeze is aborted, the temp dir is cleaned up, and a warning is printed via `echo` (not `log_warn`, which isn't defined until line 141). The script continues unfrozen. **Correct.**

**Cleanup safety:**
- `_mam_release_guard` only deletes the freeze dir if `MAM_LOOP_FREEZE_OWNED=1` (set by the freeze creator)
- `case "$MAM_LOOP_FREEZE_DIR" in */mam-loop-freeze.*) rm -rf ...` — pattern guard prevents accidental deletion of arbitrary directories. **Safe.**

**Operability Verdict: PASS**

---

## 4. Loss Perspective

### 4.1 Behaviors Preserved
- Lock acquisition/release mechanism unchanged (`mam_acquire_loop_lock` / `mam_release_loop_lock`)
- `delegate_job_safe` still runs wrapper from `$REPO_ROOT` (which is now the freeze dir — correct)
- `--all-reviewer`, `--max-loop`, `--verbose` etc. all work the same (argv preserved through re-exec)
- `.mam.env` loading preserved via `MAM_ENV_FILE` export (wrapper checks `MAM_ENV_FILE` first)

### 4.2 Behaviors Changed (Intentional)
- `run_loop.sh` now re-execs from a frozen snapshot at startup (by default)
- `_mam_release_guard` extended with freeze dir cleanup (additive — lock release still works)
- 3 git/state operations switched from `$REPO_ROOT` to `$MAM_REAL_ROOT` (necessary after freeze)
- `MAM_LOOP_NO_FREEZE=1` opt-out switch added (for testing/debugging)

### 4.3 No Unintended Losses
- No functions removed or renamed (only `orig_script` → `wrapper_script` cosmetic rename in `delegate_job_safe`)
- No environment variables removed
- No existing test modified or removed
- Old comment about "deliberately creates no copy" replaced with accurate description of freeze mechanism

**Loss Verdict: PASS**

---

## 5. Documentation Review

### 5.1 IMPROVEMENTS.md
- B-13 moved from "Section 2: Edge-case Bugs" (open) to "Section 5: Completed Tasks" (completed)
- Open task count: 3 → 2 (correct)
- Completed task count: 22 → 23 (correct, B-13 added)
- B-13 completion entry includes: freeze mechanism, B-13 layer (bash byte-offset), B-6 distinction, P1/C1/C2 corrections, cleanup logic, 5 regression guards
- Priority table updated with B-13 entry
- Test count updated to 271/271

### 5.2 VERSIONS.md
- New entry #8 added under current version section
- Covers: freeze mechanism, code/state root separation, argv preservation, `echo` fallback, `MAM_LOOP_NO_FREEZE=1`, 5 regression guards, 271/271 PASS
- Accurate and comprehensive

### 5.3 Test Name Consistency
- All 5 test names in IMPROVEMENTS.md match actual code exactly. **No discrepancies.**

**Documentation Verdict: PASS**

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## 6. Edge Cases & Safety Analysis

| Scenario | Handling | Risk |
|---|---|---|
| SIGKILL during loop | Trap doesn't fire; freeze dir leaks in `$TMPDIR` | Low — OS cleans `$TMPDIR` on reboot; no source tree pollution |
| Concurrent loops | Each gets unique `mktemp -d` name; loop lock prevents concurrent execution | None |
| Freeze copy race | Freeze happens at init before any workers start | None |
| `cp -R` with symlinks | Symlinks preserved as-is in freeze | Low — `.agents/skills/` has no external symlinks |
| Empty argv (`$#=0`) | `${MAM_LOOP_ARGV[@]+...}` guard handles empty array in bash 3.2 | None |
| `mktemp` failure | `_freeze=""`, falls through to warning + unfrozen continuation | None — graceful degradation |
| `.mam.env` absent | `[ -f "$REPO_ROOT/.mam.env" ] && export ...` — short-circuits if absent | None |

---

## 7. Summary

The B-13 Stage 2 implementation correctly addresses the self-hosting loop runtime freeze problem. The freeze snapshot mechanism is sound: it captures `.agents/skills/` into a temp directory at loop initialization and re-execs from the frozen copy, making the running loop immune to mid-loop skill edits. The code path / data path separation (`$REPO_ROOT` for code, `$MAM_REAL_ROOT` for state) is clean and correct. All 271 tests pass, including 5 new B-13 regression tests. No regressions, no losses, no lint issues.

[VERDICT: PASS]