host: a Clear that cannot remove the rotated log leaves the leaf untouched and silent - #2361

Fixes #2358

Owner: Dev-2
Reviewer: Birfy
Claim-Id: 7d328f20e3084f528c4b2b09cdd1d4c9
Branch: dev/2-p523-clear-rm-guard
Base: 8c58f3a
Tip: e3b27c0
Tree: 30425d27e18c2ce81f5e81edf56e2643edbed913
Diff: 6 files, +182/−9
Tier: T3
why: ["core/test/diagnostics.test.js: /\.(only|skip)\(/"]
basis: core/src/host/diagnostics.js=T2, core/test/diagnostics.test.js=T1, changelog.d/2358-diagnostics-clear-rm.fixed.md=T1, patches/ds-bot/0001-core-fixes.patch=T1, patches/ds-bot/0007-version-and-tooling.patch=T1, docs/subsystems/core-host.md=T0
Docs-changed: docs/subsystems/core-host.md:409 — the Clear sentence now says the removal keeps a try of its own and the truncate runs whether or not it succeeded, so the page's "cleared" matches the leaf again.

What changed

clear() removed the rotated copy and truncated the leaf in one write chain whose only handler was an empty .catch(() => {}). The rm had no try of its own, so a copy the host could not remove — a directory under that name (EISDIR), a folder without its write bit (EACCES), a busy file — rejected the chain on that line and the writeFile one line below never ran. clear() had already set cleared/fresh before the chain, so the window showed "No errors recorded." and "Cleared the error log." while the leaf still held every line, and nothing reached stderr: the leaf guard above had already passed, so refuseLeaf() did not fire.

• The rm now has a try of its own. A failure writes one console.error line that names the error code and never the folder ([ds-bot] diagnostics log rotated copy not removed: EACCES), and the truncate runs as before, whether or not the removal succeeded. The leftover bytes stay; the log the user asked to clear is empty.
• The fileKind guard keeps its place, its logic and its order: a leaf that is a link is still refused whole and nothing is truncated. clear() keeps its signature and return value; 0008 and core/client.js are untouched.

After: .1 that cannot be removed is still there, is now named on stderr, and the leaf is empty — a Clear that says it cleared no longer leaves every line on disk. The normal path is unchanged: rm succeeds, one truncation, .1 gone, no stderr line.

Test first

Two deterministic shapes added to core/test/diagnostics.test.js, both with a writable leaf so the only failure is the removal:

• #2358: clear truncates the leaf even when the rotated copy cannot be removed — logs/diagnostics.jsonl.1 is a directory, so rm without recursive raises ERR_FS_EISDIR.
• #2358: clear truncates the leaf when the folder refuses the removal — logs/ is 0555 and the leaf is 0644, so the removal raises EACCES; skipped under root with t.skip, where 0555 denies nothing, and EISDIR needs no such guard.

Both assert the leaf reads back '', .1 is still present (the directory; the file with its bytes unchanged), entries() is empty, and stderr carries exactly one line that does not contain the home folder.

On the clean base with only these tests in the tree: node --test core/test/diagnostics.test.js → 30 tests / 28 pass / 2 fail / 0 cancelled; both fail on assert.strictEqual(readFileSync(logPath, 'utf8'), '') — the leaf is truncated although the rotated copy stays and the leaf is truncated although the folder refused the removal, actual 'OLD LINE\n'×4 and the 4-line warning record. The untruncated leaf in shape B also proves the EACCES arms before the truncate, as expected. With the fix: 30 / 30 / 0.

The "no .1 at all" path stays green throughout — rm(force: true) swallows ENOENT, and the existing clear removes the rotated log, not only the leaf covers it.

Generated

patches/ds-bot/0001-core-fixes.patch and 0007-version-and-tooling.patch are the mechanical node scripts/ds-bot-patches.mjs generate output for the two edited files (src/host/diagnostics.js, test/diagnostics.test.js). The product change is core/src/host/diagnostics.js plus the test; nothing else in those patches. generate is a no-op on this tree, check reports 10 patches applying cleanly with core/ equal to ds-bot/ + patches, canonical reports generate is a no-op, and build-client.mjs --check exits 0. 0008 and core/client.js were never in git status on this branch.

The tier is T3 on the content rule \.(only|skip)\( matching the root guard's t.skip( line, not on the product change (diagnostics.js is T2 on its own); the t.skip stays as Node's per-test option form would only be a way around the pattern, not a fix, and CI's runner is not root.

Ran

node --test core/test/diagnostics.test.js
(cd core && TZ=UTC npm test)
node scripts/ds-bot-patches.mjs generate
node scripts/ds-bot-patches.mjs check
node scripts/ds-bot-patches.mjs canonical
node core/scripts/build-client.mjs --check
node .github/scripts/changelog.mjs check
TZ=UTC ARCH_DOCS_BASE=8c58f3a1c7a6511abcd2816aa545dded7ab4b99d npm run verify

verify at the committed tip: core lint 74 warnings / 0 errors, plugin lint 36 / 9 / 2 / 16 warnings and 0 errors, scripts lint 1 / 0, arch-docs: OK (6 changed file(s)), and suites 2767 + 570 + 132 + 140 + 411 + 671 + 37 + 26 = 4754 pass / 0 fail / 0 cancelled.

Not run: the smoke test and the CI package job's pack check, typecheck and actionlint, which npm run verify does not run.

Checkpoint

{
  "pr": 2361,
  "claim": "Dev-2",
  "issue": 2358,
  "summary": "clear() removed the rotated copy inside the write chain but outside a try of its own, so a copy the host could not remove rejected the chain before the truncate ran, and the empty catch kept it quiet: the window said the log was cleared while the leaf held every line. The removal now keeps a try, names the leftover on one stderr line that carries no folder, and the truncate runs whether or not it succeeded. The fileKind guard, clear()'s signature and the removal rule are unchanged.",
  "files": [
    "core/src/host/diagnostics.js",
    "core/test/diagnostics.test.js",
    "changelog.d/2358-diagnostics-clear-rm.fixed.md",
    "docs/subsystems/core-host.md",
    "patches/ds-bot/0001-core-fixes.patch",
    "patches/ds-bot/0007-version-and-tooling.patch"
  ],
  "checks": {
    "ran": "TZ=UTC ARCH_DOCS_BASE=8c58f3a1c7a6511abcd2816aa545dded7ab4b99d npm run verify",
    "result": "green",
    "at": "e3b27c0075afe3d96ebf8e6a55f797ab05a2a5ac"
  },
  "next": "none \u2014 ready for review"
}