stack/docs/compaction-refresh/reviews/GATE0-PROBE3-NEW56-S3-REVIEW-v6.md

Gate0 Probe-3 (D4) NEW-5/NEW-6 Closure — §3-Conformance Review v6

Verdict: ✅ PASS

Pin (G1 — reviewed object, mandatory)

• Reviewed object = 2d54a9dd14cb924701b2ae4ed72dae4df760c4e3 (harness commit, branch feat/827-gate0-probe, approach-(i) build; supersedes the reverted (ii) copy-to-fixture builds 7ff63cd5/6164dc07, which were NOT reviewed to a verdict).
• Reviewed file: docs/compaction-refresh/probes/p3_d4_focused_run.py — sha256 (pushed provider bytes, -o FILE, FULL-40 ref, verified before trust): 15a154df55273f51301763a984485fd63813f6d1f05d2728abb9fb8b9c040b1a (27366 bytes, no not-found sentinel).
• Co-reviewed fixture broker: p3_generation_broker.py sha256 4db4fef1ac6658a8ca79ad5091cefc901d2aa26003265c3d6726c294cf895cad — byte-identical to v5 (unchanged by this delta).

Principal-independence attestation (Mos independence ruling — process of record)

This review is produced by a distinct Opus SECREV session, orchestrator-dispatched — the ms-secrev-828 reviewer lane, dispatched by mosaic-100 — byte review only, ran nothing, and did NOT build this harness (builder = ms-rev-826). Author ≠ reviewer (Gate-16). This is one of three principals: Mos commits his own distinct-identity byte-scope-verify co-attestation at v-final, and homelab's independent verify is the third principal. (The ms-lead-reviewer Git signer identity shared across published review commits is a git-signer question routed to Mos; it does not bear on this lane's process/dispatch independence, attested here.)

NEW-5 CLOSED — approach (i): exact-byte pin, adjacent re-hash, exec in place

• Exact-byte sha256 is the trust anchor, NOT substring heuristics. Launcher bytes are read from the immutable git object (git show f4008307:<path>) and gated on sha256(launcher_bytes) == GATED_LAUNCHER_SHA256 (e950e422…) (:354). The behavior_markers in-checks (:364-372) are explicitly commented "the exact launcher digest above is the trust anchor. These marker checks are diagnostic belt-and-suspenders only, never a substitute for the pin" (:362-363). The old ordered .find() heuristic (register < initialize < execute, min<0) is gone.
• Final re-hash immediately adjacent to Popen, no interleaved yield. launch_verified_pi assembles command, then — as the statement immediately before return PiRpc(command, …) (which performs the Popen) — re-hashes the launcher: if hashlib.sha256(launcher.read_bytes()).hexdigest() != GATED_LAUNCHER_SHA256: raise (:411-412), return PiRpc(...) (:413). No harness-controlled step (no wait_path, no broker spawn) sits between the re-hash and the exec — the broker Popen + wait_path occur before launch_verified_pi is called (:611-621). Window narrowed to the fork/exec itself.
• Exec stays IN PLACE at the pinned f4008307-worktree path. The precondition returns the worktree paths gated_root / launcher_relative, gated_root / generation_relative (:378); Pi execs str(launcher) = that worktree launch-runtime.py (:390,:621), and the broker --generation-module = the worktree lease_generation.py (:614). The reverted (ii) machinery is gone: grep pinned-lease-broker / PYTHONPATH / fixture_launcher / fixture_generation / write_bytes == 0. Launcher import resolution and the file-backed fidelity surface are therefore unperturbed (this is the lower-risk approach Mos mandated over copy-to-fixture).

NEW-6 CLOSED — portable, validated, off-by-one gone

GATED_WI_ROOT is no longer the off-by-one HERE.parents[3].parent / "stack-cr-wi3-revoke". It is resolved by resolve_gated_wi_root() (:257-307): an explicit GATED_WI_ROOT env override, else repo-relative git worktree list --porcelain (from repository_root(), first parent containing .git) selecting the unique worktree whose HEAD == f4008307 and branch == refs/heads/feat/830-compaction-revoke (raise if ambiguous/absent). It then fail-closes unless gated_root.is_dir(), git rev-parse --is-inside-work-tree == "true" (:304-305), and HEAD == GATED_WI_HEAD (:306-307). Independently recomputed on this host (git query, harness not run): it resolves to the real worktree /home/hermes/agent-work/stack-cr-wi3-revoke. Portable + validated; the off-by-one is gone.

Full v4/v5 carry-over re-sweep (byte-stable vs 7f975b95 except the NEW-5/6 delta)

diff 7f975b95 → 2d54a9dd confines changes to launcher resolution (NEW-6) + adjacent-rehash-exec-in-place (NEW-5); nothing else moved. Re-swept intact: creds-scrub (scrub_fixture_credentials + outermost finally); source-invalid ABSENT (grep=0 both files); fidelity file-backed unperturbed (broker read_runtime_generation/bump_runtime_generation on the fixture .state; assert_d4 generation_source=="state-file" + state_file_drives_lifecycle + state_file_in_fixture_root + new→MUTATOR_UNVERIFIED/prior→STALE_GENERATION); lease_anchor_registered INTACT (event + hex-256); live-path gated launcher; fail-closed precondition; fixture-socket isolation; -O-safe (0 bare assert, PASS derived); allow-list env (0 os.environ.copy); --runs choices=(3,); single p3 broker (broker byte-identical to v5). ABSENT sweep = 0 (P5/P6/P2-bank/retry-launder/mosaic-yolo/execRuntime/pi_gate0/run_open/ atomic; extension actions only bump/lifecycle/authorize/promote; no exec-at-import). Beyond-R1 tripwire: not tripped — exec is in place, imports and the file-backed observation surface untouched; no isolation crossing.

Verdict

PASS @ 2d54a9dd. NEW-5 (approach (i): exact-byte sha256 pin as trust anchor; adjacent re-hash immediately before Popen with no interleaved yield; exec in place at the pinned f4008307-worktree path; (ii) copy-to-fixture/ PYTHONPATH machinery reverted) and NEW-6 (portable, validated, off-by-one-gone root resolution) are both closed; the full v4/v5 carry-over holds byte-stable except the two intended surfaces; ABSENT sweep is 0; the R1 file-backed fidelity surface is unperturbed. Zero out-of-scope surface.

Findings: none.

Scope reminder (not a finding)

Producing this evidence executes the Gate0 mechanism (§3/§5). This review clears bytes only; FIRE remains separately gated on Mos's explicit post-clear GO and is not authorized by this review.

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Reviewer: distinct Opus SECREV session (ms-secrev-828 lane, dispatched by mosaic-100), Gate-16 author≠reviewer, byte review only; ran nothing; did not build. Reviewed object (pin): 2d54a9dd14cb924701b2ae4ed72dae4df760c4e3 · harness sha256 15a154df55273f51301763a984485fd63813f6d1f05d2728abb9fb8b9c040b1a.