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docs/decisions/2026-04-24-pm-ratify-lock-semantics-path-l1.md

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+# LOCKED — PM-RATIFY-LOCK-SEMANTICS Path L-1
+
+**Date**: 2026-04-24
+**Ratified by**: Marko Marković (via PM verified evidence)
+**PM**: claude-opus-4-7 (Cowork)
+**Prerequisite gate**: 1/3 (Task #29 progress)
+
+## Odluka
+
+**Path L-1 RATIFIED.** §7.4 `concurrent_runners: FORBIDDEN` pokriva cross-process threat model. Intra-wrapper `--parallel-concurrency N` spawns preko fail-open TOCTOU race. Manifest v4 anchor `dedd698` ostaje validan. Code freeze HEAD `373516c` nepromenjen. Bez manifest v5 reemisije.
+
+## Waiver tekst (authoritative)
+
+> §7.4 applies only to cross-process invocations. Intra-wrapper parallel spawns under `--parallel-concurrency N` are exempt. HEAD `373516c` behaviour satisfies the intent.
+
+## Evidence verified
+
+- `runner-lock.ts:77-112` check-then-write pattern confirmed. TOCTOU prozor između readExistingLock i fs.writeFileSync.
+- `runner.ts:67-72` + 848-851 intent explicitly cross-process ("sentinel contend regardless of their --output paths")
+- Gate D halt log: pid 4984 + pid 65668 oba logovali `[bench:lock] acquired` unutar 3s, file retained last-writer pid=65668
+
+## Path L-2 rejection rationale
+
+Per-cell sentinel ili O_EXCL flag edit zahteva izmenu u `runner.ts:852` i/ili `runner-lock.ts`, oba frozen per manifest v4 §11. Triggers manifest v5 reemisiju. Ne opravdano kada L-1 waiver drži.
+
+## Artefact
+
+- Memo: `benchmarks/results/manifest-v4-lock-semantics-clarification.md`
+- Memo SHA-256: `f410b4f5e6c97c405cd39c51c385dfca9079a6f80a0a296a904309d5ab239d83`
+- Anchor commit: `67eb89914a49ec38049379bf952d5f62b82c188d` on `feature/c3-v3-wrapper`
+
+## Task 2.6 carry-over ticket
+
+**`bench-lock-exclusive-create`** (defensive upgrade, Stage-3-independent):
+- Swap `fs.writeFileSync` → `fs.openSync(path, 'wx')` (O_EXCL) in `runner-lock.ts`
+- Per-cell sentinel path in `runner.ts:852`
+- Parallel-acquire unit test (exactly one succeeds, other throws)
+
+## Next gate
+
+CC-1 authorized to advance to §1.2 Runner Early-Exit RCA memo. No self-advance to N=400 re-kick.