feat: harvest 4 — the kit as applied: settings liveness, the hook stdin/exit contract, the exercised fork detector, and the rest of #58

[j4th]

Closes #58
Closes #33

Summary

Harvest 4: every finding on #58 with a proven fix, landed in the kit so the next sync of any target is a merge against a kit that has already absorbed what applying it taught. The two syncs of e92e9c4 (you-are-hear #42 → PR #43; echosphere ECH-40 → PR #37) were mechanical where the kit intended; what they found afterwards was not lint: a hook-shaped object at the top level of settings.json makes the harness discard the whole settings file (read from the 2.1.278 bundle: the diagnostic is fatal and the parser returns no settings — hooks, enabledMcpjsonServers and enabledPlugins all inert, silently, block green), every hook checked its dependency before draining stdin and three sites decided on printf | grep -q (a >64 KiB commit body bypassed the main-branch deny outright), and the Stop-tier fork detector blocked a hosted review's own hand-off on the action's staging copy.

Design: docs/superpowers/specs/2026-09-21-cascade-kit-harvest-4-design.md (D30–D40, clusters H1–H7). Plan: docs/superpowers/plans/2026-09-21-harvest-4-applied-defects.md. One commit per task; the verification block green after every commit through its new runner.

What lands, by cluster

• H4 · Verification block (9a50c8b) — run-verification-block.sh with two fail-loud rails (empty extraction is red; exit 0 without the done sentinel is red), the advisory-exemplar arm kit-tree-only with a project-side ADVISORY_WIRED declaration, the .mcp.json.example operand guarded, the launch-root dry-runs keep the hook's stderr, and the kit's own CI (verify.yml, no path filter) runs the block on every PR.
• H1 · Settings liveness (e4fa8a9, d5eba3a) — both _example_PostToolUse_* objects deleted; the registration stanza lives in each advisory hook's Register: header; the registry comment names the invariant and both memory scopes; § Hook authoring states it with its evidence; the block asserts no top-level key besides hooks holds a hook-shaped object — flat or nested, since the loader reads a matcher or a non-empty hooks at depth ≤ 3.
• H2 · The stdin/exit contract (4995130, bba0834, 6a72b36, b7ca5a0) — the contract text with Depends: in the header shape, carried by all three hooks authored with the section; drain-first in every hook and here-strings at the three decision sites; hook-contract-fixture.sh (two structural checks over every hook plus over-buffer probes on the main-branch deny, the PR-state ask and the detector's second stop), run by the block.
• H3 · The fork detector (6a72b36, fc8237a) — the exercised body: ignore-driven prune with the three safety rules, find's stderr behind a writability probe, ./.claude-pr pruned unconditionally, a tooling path named as not-a-fork, the residual in the header; § .gitignore anchoring names /.claude-pr/; a first-stop fixture probe on a tree that discriminates every prune rule, the staging-copy prune and the degrade path.
• H5 · Harness and workflows (63a25ed, 822fdc6, 79d6c2f, 47e8c8a, 86b58d7) — agent-cost.py per-tier cache reads (0.025× on the top tier) with new fixture rows, and its totals summed without the throwaway dict; review-sweep.js boundary-safe hint match, .catch on the roster read, index-list retry reindex; finish-ab.js distinct arm labels, hallucinations ?? [] at both sites, effort read once; both stub harnesses stop swallowing their own exceptions; nine new harness scenarios, two of them the mixed-outcome retry case that tells i from k.
• H6 · Records and the executor (98bb5cb, a8fc48d, 1d810a6, 77b80aa, c2745e3) — /finish Step 1 admits [<slug>:meta] in the contract and in the procedure pair; adr-new writes the index row in the index's own form, states no count, defines Promotes:; the ADR reviewer cites by the register's id form; the duplicated citation, the marker spelling, the pre-flight Quick-reference row, the stamped-state callouts, the cwd disagreement named in the guard header, pubspec.lock and a *.lock fallback arm (both now fixture-probed, fc8237a); the Kit commit row and § Syncing the kit.
• H7 · Templates and the matcher (df2ce35) — checks: read twice in both review-workflow templates, the base ref fetched after the head-sha checkout, an explicit degrade clause for a diff past the turn cap; the knowledge-backend matcher widened to the live tool set, dated.

Review gate

• /simplify — not run: kit content (bash, markdown, small JS/Python); the sweep's code-review and comment-accuracy dimensions cover the same ground on this diff.
• pr-review-toolkit:review-pr — not run as a skill: the kit is reviewed by its own dogfooded sweep (below), which dispatches the same dimension set as ad-hoc agents.
• review-sweep — ran: 6 finders + 8 verifiers, 5 confirmed / 3 refuted / 2 unverified, dropped coverage: none, bounds 3/8

Six sonnet finders (code-review, silent-failure, comment-accuracy, test-coverage, kit-conformance, port-fidelity) at effort medium with a high-effort retry; opus verifiers at high, refute-by-default; ten deduplicated findings, eight verified, two returned unverified by the bound.

Triage

Confirmed → Apply (5 of 5), each its own commit with the block green after it:

1. cbk-conventions-reference.md:621 — the hook-shape invariant read only depth 1; D30 states depth ≤ 3. Recursive scan (d5eba3a); red on a nested stanza, a flat one and a depth-3 matcher; silent on an empty hooks array, a string value and the clean tree.
2. cbk-conventions-reference.md:396 — Depends: joined the header shape but only the detector carried it, contradicting "the three hooks authored with this section carry every line". The two other 2026-09-06 hooks get the line (b7ca5a0); each restates what its fail-open branches already print. Surfaced, not applied: the six earlier hooks keep their unlabelled fail-open sentences under the section's bring-up-when-next-edited clause; whether this harvest's drain-move edit counts as that edit is the operator's call (the verifier read it as a documentation expansion).
3. plans/…harvest-4…md:211 — the ADVISORY_WIRED mutation recipe tripped an earlier kit check and expected a green project sub-block a kit copy cannot reach. Rewritten from a live run with both preconditions and the double-registration direction (04a791e).
4. detect-forked-agent-memory.sh:89 — the three prune rules, the staging-copy prune and the degrade path had no fixture; every one removed shipped green. One first-stop probe on a tree with a directory literally named * discriminates all of them (fc8237a); measured red under each of five mutations.
5. finish-procedure.md:33 (both copies) — the procedure restated three title forms with a halt on anything else while the contract admits [<slug>:meta]. Both copies widened, pair byte-parallel (c2745e3).

Unverified (the verify bound) → Apply on the caller's own reproduction (2 of 2):

6. protect-lock-files.sh:71 — the pubspec.lock arm and the *.lock fallback had no automated probe. Three probes in the fixture (fc8237a); red when pubspec.lock leaves the named list and when the fallback arm is renamed.
7. review-sweep-accounting.mjs:184 — the reindex was exercised with one failure at index 0, where i = k. Two-failure mixed-outcome scenarios in both harnesses (86b58d7); the review-sweep one is red under results[k]. finish-ab's existing single-failure scenario already sat at index 1 and caught judged[k] on its own; the new one adds the mixed case.

Refuted → Reject (3 of 3):

• "ADVISORY_WIRED's three directions never run in kit CI" — the project sub-block's scaffold-file gate is pre-existing and deliberate (D-P-2); the arm's four directions were driven live on a synthetic target, and that recipe is now in the plan (item 3). Surfaced: a synthetic-target fixture so the project sub-block runs in kit CI is a design call, not a line.
• "Depends: is neither enforced nor applied to seven hooks" — the section states, in a line this harvest did not touch, that Tier: is the one block-asserted line and adoption is incremental; the narrow self-contradiction is item 2.
• "_comment_hooks overclaims the header contract" — the comment delegates the shape to § Hook authoring and never mentions Depends:.

One process note: the silent-failure finder mutated the kit's .claude/settings.json in place for its probe and restored it (the tree was clean at triage); its verifier worked on a copy. The sweep's finder prompts do not say "probe on a copy"; worth a line in the next harness pass.

Verification

• Always-loaded total: 130,405 → 130,628 bytes (+223: the § Syncing the kit pointer heading in the contract; the retired pre-flight Quick-reference row is −107). Recorded in the README as the figure a fresh target starts from.
• Every task's proof by mutation: the runner's two rails (heading renamed so the extraction is empty; sentinel renamed) both red; the ADVISORY_WIRED arm red when undeclared, passing when declared, red when double-registered (synthetic target, recipe in the plan); the hook-shape invariant red on an injected object, flat and nested; the over-buffer commit-body probe exit 0 before the here-string swap and exit 2 after; the fixture's two structural checks red on a removed drain and a re-introduced pipe; the detector probe red under each prune rule removed, the staging-copy prune removed and the degrade path exiting clean; the lock-file probes red under a dropped pubspec.lock arm and a renamed fallback; agent-cost red at $11.00 with the per-tier map emptied; review-sweep red on the reverted boundary match, on the dropped .catch and on a results[k] misindex; finish-ab red on the dropped label check, crashing on the dropped hallucinations guard, red on a judged[k] misindex.
• Tasks 5 and 6 landed as one commit (6a72b36): the fixture's structural checks read every hook, so the fixture and the detector's rewrite are not separately green.
• The executor pair byte-parallel; the procedure pair byte-parallel; the adr-starters mirror identical to docs/adr/; every SKILL.md under 500 lines; no _example_ key in settings.json; sanitization grep clean (no target-project identifier; the two public run names only beside their issue citations).
• Not harvested, per the spec's § Non-goals: the collect-then-exit block shape, a shared hook helper library, spellchecker configuration for the bracket idiom, a file-count-scaled --max-turns.

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