fix(host): refuse a workflow folder that cannot be listed - #2615

Verdict: PASS at a4f3735
Written-by: Reviewer
Attestation: a4f3735 role=Reviewer

Ran at this tip:

$ cd core && TZ=UTC DSH_HARNESS=/data/dsh/bot/workspace/d2607/repo/core/dev/harness node --import ./test/harness-resolve.mjs --test test/workflow-store.test.js
# tests 25  # pass 25  # fail 0
$ cp /data/dsh/bot/workspace/w2615/base-store.js /data/dsh/bot/workspace/w2615/tip/core/src/host/workflow-store.js
$ cd core && TZ=UTC DSH_HARNESS=/data/dsh/bot/workspace/d2607/repo/core/dev/harness node --import ./test/harness-resolve.mjs --test test/workflow-store.test.js
# tests 25  # pass 23  # fail 2
$ cp /data/dsh/bot/workspace/w2615/tip-store.js.keep /data/dsh/bot/workspace/w2615/tip/core/src/host/workflow-store.js
$ cd core && TZ=UTC DSH_HARNESS=/data/dsh/bot/workspace/d2607/repo/core/dev/harness node --import ./test/harness-resolve.mjs --test test/workflow-store.test.js
# tests 25  # pass 25  # fail 0
$ TZ=UTC DSH_HARNESS=/data/dsh/bot/workspace/d2607/repo/core/dev/harness node --import ./test/harness-resolve.mjs /tmp/repro2615.mjs
# reproduce: customize ok -> chmod 0o311 -> list workflow/unreadable (no own) / save ok:false wrote:true changed:true / open ok:true / chmod 0o755 -> list own ['mine']
$ node scripts/ds-bot-patches.mjs check
# skipped pin (no git)  ok 10 patches apply cleanly in order  ok core/ equals ds-bot/ + patches/ds-bot/
$ cd core && npx --no-install oxlint src test
# Found 81 warnings and 0 errors.
$ node .github/scripts/changelog.mjs check
# changelog: 17 fragment(s) in changelog.d/ are well formed

Review points:

• Scope: exactly the 6 files the brief names, each blob matches the tip (core store dca74aa0, test a6596ac9, docs e032144b, changelog f3f5775f). No core/client.js, ruleset, CI or other subsystem touched; base a754cc4e compare returns the same 6.
• (a) Source only changed what it should: ownFiles() keeps if (!folderReal()) return [] and no longer catches readdirSync; list() converts the failure to refuseUnreadable() (workflow/unreadable, no own key); save() computes wrote and, when the list refuses, returns that refusal plus id/wrote/changed instead of spreading an empty own into ok:true; setDefault() same; open() spreads the listing only when listed.ok. readOwn()'s JSON.parse catch, definitions() / rt.workflowDefinitions() preset fallback, folderReal/folderWritable/fileWritable are untouched (diff shows zero hunks there).
• (b) Mirrors: cmp says patches/ds-bot/files/src/host/workflow-store.js and .../test/workflow-store.test.js are byte-identical to their core/ files, and both pairs share one blob sha (dca74aa0 / a6596ac9).
• (c) #2068 probes: WORKFLOW_PROBES test is green (test 15), sinks and gates still match one-to-one, and this change adds no new join(dir, …) sink — the new refusal only names dir in its message.
• Red first: with the base blob the same suite is 23/25, failing only not ok 24 and not ok 25 — the new list() assertion at core/test/workflow-store.test.js:554 (listed.ok true !== false) and the new save() assertion at :579 (saved.ok); restoring the tip file returns 25/25.
• Independent reproduction on a real folder (not just the tests): customize writes mine; chmod 0o311 makes list() ok:false/workflow/unreadable with no own, save() ok:false with wrote:true/changed:true and the bytes really land (mine.json name Mine 2 on disk), open('mine') stays ok:true; a no-op save reports wrote:false; chmod 0o755 lists mine again.
• CI at the tip: tests-ok success, merge-gate success, every other run success; only enqueue-guard is red because no PASS existed yet — the expected pre-review state.
• Checkpoint block is valid: 1180 chars (<1500), summary 443 chars (<600), next 23, pr 2615 / claim Dev / issue 2614, 6 files all in this diff, checks.at the full tip sha.

Not run: the full npm run verify (the shared host is running other lines) and the smoke test (no index.js / host boot change).