feat: context rot defense for /ship — subagent isolation + clean step numbering (v0.18.1.0) (#1030)

* refactor: renumber /ship steps to clean integers (1-20)

Replaces fractional step numbers (1.5, 2.5, 3.25, 3.4, 3.45, 3.47, 3.48,
3.5, 3.55, 3.56, 3.57, 3.75, 3.8, 5.5, 6.5, 8.5, 8.75) with clean
integers 1 through 20, plus allowed resolver sub-steps 8.1, 8.2,
9.1, 9.2, 9.3. Fractional numbering signaled "optional appendix" and
contributed to /ship's habit of skipping late-stage steps.

Affects:
- ship/SKILL.md.tmpl (all headings + ~30 cross-references)
- scripts/resolvers/review.ts (ship-side 3.47/3.48/3.57/3.8 conditionals)
- scripts/resolvers/review-army.ts (ship-side 3.55/3.56 conditionals)
- scripts/resolvers/testing.ts (ship-side 2.5/3.4 references, 5 sites)
- scripts/resolvers/utility.ts (CHANGELOG heading gets Step 13 prefix)
- test/gen-skill-docs.test.ts (5 step-number assertions updated)
- test/skill-validation.test.ts (3 step-number assertions updated)

/review step numbering (1.5, 2.5, 4.5, 5.5-5.8) intentionally unchanged —
only the ship-side of each isShip conditional was updated.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* feat: subagent isolation for /ship's 4 context-heaviest sub-workflows

Fights context rot. By late /ship, the parent context is bloated with
500-1,750 lines of intermediate tool output from tests, coverage audits,
reviews, adversarial checks, and PR body construction. The model is
at its least intelligent when it reaches doc-sync — which is why
/document-release was being skipped ~80% of the time.

Applies subagent dispatch (proven pattern from Review Army at Step 9.1
and Adversarial at Step 11) to four sub-workflows where the parent
only needs the conclusion, not the intermediate output:

- Step 7 (Test Coverage Audit) — subagent returns coverage_pct, gaps,
  diagram, tests_added
- Step 8 (Plan Completion Audit) — subagent returns total_items, done,
  changed, deferred, summary
- Step 10 (Greptile Triage) — subagent fetches + classifies, parent
  handles user interaction and commits fixes (AskUserQuestion + Edit
  can't run in subagents)
- Step 18 (Documentation Sync) — subagent invokes full /document-release
  skill in fresh context; parent embeds documentation_section in PR body

Sequencing fix for Step 18: runs AFTER Step 17 (Push) and BEFORE Step 19
(Create PR). The PR is created once from final HEAD with the
## Documentation section baked into the initial body — no create-then-
re-edit dance, no race conditions with document-release's own PR body
editor.

Adds "You are NOT done" guardrail after Step 17 (Push) to break the
natural stopping point that currently causes doc-release skips.

Each subagent falls back to inline execution if it fails or returns
invalid JSON. /ship never blocks on subagent failure.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* test: regression guard for /ship step numbering

Three regression guards in skill-validation.test.ts to prevent future
drift back to fractional step numbering:

1. ship/SKILL.md.tmpl contains no fractional step numbers except the
   allowed resolver sub-steps (8.1, 8.2, 9.1, 9.2, 9.3). A contributor
   adding "Step 3.75" next month will fail this test with a clear error.

2. ship/SKILL.md main headings use clean integer step numbers. If a
   renumber accidentally leaves a decimal heading, this catches it.

3. review/SKILL.md step numbers unchanged — regression guard for the
   resolver conditionals in review.ts/review-army.ts. If a future edit
   accidentally touches the review-side of an isShip ternary, /review's
   fractional numbering (1.5, 4.5, 5.7) would vanish. This test catches
   that cross-contamination.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* docs: sync ship step references after renumber

CLAUDE.md: "At /ship time (Step 5)" → "(Step 13)" — CHANGELOG is now
  explicitly Step 13 after the renumber (was implicit between old
  Step 4 and Step 5.5).
TODOS.md: "Step 3.4 coverage audit" → "Step 7" — references the open
  TODO for auto-upgrading ★-rated tests, which hooks into the coverage
  audit step.

Both are historical references to ship's step numbering that became
stale when clean integer renumbering landed in 566d42c2.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* test: update golden ship skill baselines after renumber + subagent refactor

The golden fixtures at test/fixtures/golden/{claude,codex,factory}-ship-SKILL.md
regression-test that generated ship/SKILL.md output matches a committed baseline.
After renumbering steps to clean integers and converting 4 sub-workflows to
subagent dispatches, the generated output changed substantially — refresh the
baselines to reflect the new expected output.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* chore: bump version and changelog (v0.18.1.0)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* chore: gitignore Claude Code harness runtime artifacts

.claude/scheduled_tasks.lock appears when ScheduleWakeup fires. It's a
runtime lock file owned by the Claude Code harness, not project source.
Add .claude/*.lock too so future harness artifacts in that directory
don't need their own gitignore entries.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,19 @@
 # Changelog
 
+## [0.18.2.0] - 2026-04-17
+
+### Fixed
+- **`/ship` stops skipping `/document-release` ~80% of the time.** The old Step 8.5 told Claude to `cat` a 2500-line external skill file *after* the PR URL was already output, at which point the model had 500-1,750 lines of intermediate tool output in context and was at its least intelligent. Now `/ship` dispatches `/document-release` as a subagent that runs in a fresh context window, *before* creating the PR, so the `## Documentation` section gets baked into the initial PR body instead of a create-then-re-edit dance. The result: documentation actually syncs on every ship.
+
+### Changed
+- **`/ship`'s 4 heaviest sub-workflows now run in isolated subagent contexts.** Coverage audit (Step 7), plan completion audit (Step 8), Greptile triage (Step 10), and documentation sync (Step 18) each dispatch a subagent that gets a fresh context window. The parent only sees the conclusion (structured JSON), not the intermediate file reads. This is the pattern Anthropic's "Using Claude Code: Session Management and 1M Context" blog post recommends for fighting context rot: "Will I need this tool output again, or just the conclusion? If just the conclusion, use a subagent."
+- **`/ship` step numbers are clean integers 1-20 instead of fractional (`3.47`, `8.5`, `8.75`).** Fractional step numbers signaled "optional appendix" to the model and contributed to late-stage steps getting skipped. Clean integers feel mandatory. Resolver sub-steps that are genuinely nested (Plan Verification 8.1, Scope Drift 8.2, Review Army 9.1/9.2, Cross-review dedup 9.3) are preserved.
+- **`/ship` now prints "You are NOT done" after push.** Breaks the natural stopping point where the model was treating a pushed branch as mission-accomplished and skipping doc sync + PR creation.
+
+### For contributors
+- New regression guards in `test/skill-validation.test.ts` prevent drift back to fractional step numbers and catch cross-contamination between `/ship` and `/review` resolver conditionals.
+- Ship template restructure: old Step 8.5 (post-PR doc sync with `cat` delegation) replaced by new Step 18 (pre-PR subagent dispatch that invokes full `/document-release` skill with its CHANGELOG clobber protections, doc exclusions, risky-change gates, and race-safe PR body editing). Codex caught that the original plan's reimplementation dropped those protections; this version reuses the real `/document-release`.
+
 ## [0.18.1.0] - 2026-04-16
 
 ### Fixed