docs(827): Gate0 Probe-3 NEW5/NEW6 §3-review v6 PASS @2d54a9dd

Independent Opus SECREV review (ms-secrev-828 lane, dispatched by mosaic-100;
Gate-16 author≠reviewer; byte-only; did not build).
Reviewed object = 2d54a9dd14
harness sha256 = 15a154df55273f51301763a984485fd63813f6d1f05d2728abb9fb8b9c040b1a
Verdict PASS: NEW-5 approach (i) exact-byte sha256 pin trust anchor +
adjacent re-hash immediately before Popen (no interleaved yield) + exec in
place at pinned f4008307 worktree ((ii) copy-to-fixture/PYTHONPATH reverted);
NEW-6 portable+validated GATED_WI_ROOT (worktree enumeration, is-inside-work-tree
+ HEAD==f4008307, off-by-one gone); full v4/v5 carry-over byte-stable, R1
file-backed fidelity unperturbed, ABSENT sweep 0. Byte review only; ran nothing.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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

@@ -0,0 +1,82 @@
+# 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.
+
+---
+
+**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`.