fix(workflow): keep a read-only host out of reap and dispose - #2674

Written-by: Dev

Fixes #2673

A read-only host is the second DSH window on the same DSH_HOME — the reader core/src/host/home-lock.js describes. It implemented readOnly() on eleven endpoints but not on the two lifecycle paths that write the whole store: loading the plugin called reap(), closing the window called dispose(), and both treated every run still marked running as one whose host had died — endRun(..., { code: 'host-ended' }), releaseAll(run.ephemeral), then a whole-store writeback from the reader's older copy.

reap() now returns immediately when readOnly() is true, next to the existing typeof release !== 'function' guard; dispose() clears its local timers and returns Promise.resolve() without ending runs, releasing step Bots or writing. The writer path (readOnly: () => false) is untouched: same endRun, same releaseAll, same write.

Owner: Dev
Reviewer: Reviewer

Red first

plugins/workflow/test/service.test.js (new; the issue's acceptance command), run against main 656fadab71170275eeeb924fdfddc33f8072ba81 with the implementation unchanged:

cd plugins/workflow && TZ=UTC DSH_HARNESS=<core>/dev/harness \
  node --import ./test/resolve.mjs --test test/service.test.js

not ok 1 - #2673: a read-only host does not reap the writer's live run
  error: the read-only host overwrote the writer's store
not ok 2 - #2673: a read-only host does not dispose the writer's live run
  error: the read-only host overwrote the writer's store
not ok 3 - #2673: a read-only host releases none of the writer's step Bots
  error: reap() released the writer's step Bots
  + [ 'eph-plan-1', 'eph-code-2' ]
ok 4 - #2673: a writable host still reaps and disposes the run it did not start
# tests 4  # pass 1  # fail 3

Both red lifecycles wrote the reader's stale copy: lane.active emptied, last.status = 'failed', failure.code = 'host-ended' — the writer's just-written plan: done / code: running overwritten. Test 4 is the writer-side guard and passed before and after.

Ran at this tip: 644cde0

• cd plugins/workflow && TZ=UTC DSH_HARNESS=<core>/dev/harness node --import ./test/resolve.mjs --test test/service.test.js test/assign.test.js — 24/24 pass
• cd plugins/workflow && TZ=UTC DSH_HARNESS=<core>/dev/harness node --import ./test/resolve.mjs --test "test/*.test.js" — 479 pass, 0 fail (the whole plugin suite: dispose, ephemeral, host, service)
• node .github/scripts/changelog.mjs check — 23 fragments well formed

The four files were uploaded as blobs and the branch tree was compared against main 656fadab71170275eeeb924fdfddc33f8072ba81: status: ahead, 1 ahead, 0 behind, exactly these four paths — no file I did not touch.

Not run

• npm run verify (whole repo): this box runs one full suite at a time; the only package touched is plugins/workflow and its suite ran in full above.
• npm run lint / oxlint: no node_modules on this box, so oxlint is not installed.
• arch-docs: it reads git log, and there is no git binary here. Its requirement is met the other way — the owned page docs/subsystems/workflow.md is in this commit.

Docs

docs/subsystems/workflow.md: the lifecycle paragraph now states the read-only boundary (a reader neither reaps nor disposes; the writer's own reap decides). No Docs-not-needed: trailer.

{
  "pr": 2674, "claim": "Dev", "issue": 2673,
  "summary": "A second, read-only DSH window on the same home no longer reaps or disposes the writer's live workflow. reap() returns at once when readOnly() is true, the way it already returns without a release hook, and dispose() clears only its local timers before returning Promise.resolve() — no endRun, no releaseAll, no store write. The writer path (readOnly: () => false) is unchanged, guarded by its own test.",
  "files": ["plugins/workflow/src/service.js", "plugins/workflow/test/service.test.js", "docs/subsystems/workflow.md", "changelog.d/2673-readonly-reap.fixed.md"],
  "checks": { "ran": "cd plugins/workflow && TZ=UTC DSH_HARNESS=<core>/dev/harness node --import ./test/resolve.mjs --test \"test/*.test.js\"", "result": "green", "at": "644cde0b4abfdd644fba43a0f992c6f95b61cc03" },
  "next": "none — ready for review"
}

Checkpoint

{
  "pr": 2674,
  "claim": "Dev",
  "issue": 2673,
  "summary": "A read-only host is the second DSH window on the same home, and loading the plugin or closing that window used to end the writer's live runs, release their step Bots and write its older store copy over the newer one. reap() and dispose() now return before touching the record when readOnly() is true, while dispose() still clears only its own timers. The writer path, readOnly: () => false, is unchanged and a test guards it. The new tests hold a writer's run and assert the reader's release stub is never called.",
  "files": [
    "plugins/workflow/src/service.js",
    "plugins/workflow/test/service.test.js",
    "docs/subsystems/workflow.md"
  ],
  "checks": {
    "ran": "cd plugins/workflow && TZ=UTC node --import ./test/resolve.mjs --test \"test/*.test.js\"",
    "result": "green",
    "at": "644cde0b4abfdd644fba43a0f992c6f95b61cc03"
  },
  "next": "none — ready for review"
}