fix(ship): name the /document-release subagent at every Step 18 decision point

The v1.54.0.0 carve moved Step 18 (documentation sync) into
ship/sections/pr-body.md and the Claude-host skeleton stopped saying
"document-release" anywhere in the workflow body — the dispatch became
invisible at exactly the moments an agent decides whether to open the
section. Restore visibility at three touchpoints, all subagent-framed
(never bare-slash-framed, which would invite an inline Skill invocation
that bypasses the fresh-context subagent + JSON contract):

- manifest trigger (renders into the section-index row AND the STOP
  pointer): "dispatching the /document-release subagent to sync docs
  (Step 18) and then creating or updating the PR/MR (Step 19)"
- Step 17 handoff line names Step 18's dispatch explicitly
- new hoisted doc-sync invariant beside the PR-title invariant: the
  dispatch itself is never skipped; only a failed subagent is
  non-blocking

Pin it in carve-guards: 'the /document-release subagent' (all three
touchpoints) + 'dispatches the /document-release subagent' (invariant)
must stay in the skeleton; the carved imperative 'Dispatch
/document-release as a subagent' must stay carved. Skeleton cap
91,600 → 92,300 (measured 91,764; trigger renders twice). Goldens
regenerated for all three hosts.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ship/SKILL.md

@@ -937,7 +937,7 @@ sections. Read a section in full before doing its step; do not work from memory.
 | addressing Greptile review comments when a PR exists (Step 10) | `sections/greptile.md` |
 | the adversarial review and learnings capture (Step 11) | `sections/adversarial.md` |
 | writing the CHANGELOG entry (Step 13) | `sections/changelog.md` |
-| syncing docs and creating or updating the PR/MR (Steps 18-19) | `sections/pr-body.md` |
+| dispatching the /document-release subagent to sync docs (Step 18) and then creating or updating the PR/MR (Step 19) | `sections/pr-body.md` |
 
 ---
 
@@ -1417,13 +1417,15 @@ If `ALREADY_PUSHED`, skip the push but continue to Step 18. Otherwise push with
 git push -u origin <branch-name>
 ```
 
-**You are NOT done.** The code is pushed but documentation sync and PR creation are mandatory final steps. Continue to Step 18.
+**You are NOT done.** The code is pushed but Step 18 (dispatch the /document-release subagent to sync docs) and Step 19 (create the PR/MR) are mandatory final steps. Continue to Step 18.
 
 ---
 
 **PR/MR title invariant (always applies — do not skip even if you don't open the section below):** Any PR or MR you create OR update in the next step MUST have a title that starts with `v$NEW_VERSION` (the version bumped in Step 12), in the format `v<NEW_VERSION> <type>: <summary>`. Never create or edit a PR/MR title without this prefix. Compute the correct title with the single source of truth helper: `~/.claude/skills/gstack/bin/gstack-pr-title-rewrite.sh "$NEW_VERSION" "<current title>"`. The full create/update procedure (idempotency, redaction scan, self-check) is in the section below.
 
-> **STOP.** Before syncing docs and creating or updating the PR/MR (Steps 18-19), Read `~/.claude/skills/gstack/ship/sections/pr-body.md` and execute it
+**Doc-sync invariant (always applies — do not skip even if you don't open the section below):** Step 18 dispatches the /document-release subagent BEFORE the PR/MR is created or updated in Step 19. Never skip the dispatch itself; only a failed subagent is non-blocking (proceed to Step 19 without a `## Documentation` section).
+
+> **STOP.** Before dispatching the /document-release subagent to sync docs (Step 18) and then creating or updating the PR/MR (Step 19), Read `~/.claude/skills/gstack/ship/sections/pr-body.md` and execute it
 > in full. Do not work from memory — that section is the source of truth for this step.
 
 ## Step 20: Persist ship metrics

ship/SKILL.md.tmpl

@@ -496,12 +496,14 @@ If `ALREADY_PUSHED`, skip the push but continue to Step 18. Otherwise push with
 git push -u origin <branch-name>
 ```
 
-**You are NOT done.** The code is pushed but documentation sync and PR creation are mandatory final steps. Continue to Step 18.
+**You are NOT done.** The code is pushed but Step 18 (dispatch the /document-release subagent to sync docs) and Step 19 (create the PR/MR) are mandatory final steps. Continue to Step 18.
 
 ---
 
 **PR/MR title invariant (always applies — do not skip even if you don't open the section below):** Any PR or MR you create OR update in the next step MUST have a title that starts with `v$NEW_VERSION` (the version bumped in Step 12), in the format `v<NEW_VERSION> <type>: <summary>`. Never create or edit a PR/MR title without this prefix. Compute the correct title with the single source of truth helper: `~/.claude/skills/gstack/bin/gstack-pr-title-rewrite.sh "$NEW_VERSION" "<current title>"`. The full create/update procedure (idempotency, redaction scan, self-check) is in the section below.
 
+**Doc-sync invariant (always applies — do not skip even if you don't open the section below):** Step 18 dispatches the /document-release subagent BEFORE the PR/MR is created or updated in Step 19. Never skip the dispatch itself; only a failed subagent is non-blocking (proceed to Step 19 without a `## Documentation` section).
+
 {{SECTION:pr-body}}
 
 ## Step 20: Persist ship metrics

ship/sections/manifest.json

@@ -56,7 +56,7 @@
       "id": "pr-body",
       "file": "pr-body.md",
       "title": "Documentation sync + PR/MR creation",
-      "trigger": "syncing docs and creating or updating the PR/MR (Steps 18-19)"
+      "trigger": "dispatching the /document-release subagent to sync docs (Step 18) and then creating or updating the PR/MR (Step 19)"
     }
   ]
 }