feat(file-safety): land safeWriteText as its own unit (u1 of the #2357 split plan, content unchanged) - #2385

Failed checks: 2 errors · 2 warnings

Check name	Status	Explanation	Resolution
Security Boundaries		The Windows DACL leak remains in the new src/services/file-safety/safeWriteText.ts. Staging content is written before DACL capture (lines 727–827), and a backup is copied without the target DACL (li…	Protect staging and backup files with appropriate Windows DACLs before writing content. Apply the target DACL before publication and report ACL failures. Add Windows tests for restrictive target DACLs and restore failures.
Persistence Integrity		The prior failure remains unresolved. In safeWriteText.ts:996-1002,1067-1074, a failIfExist write can publish a hard link and silently succeed when staging unlink fails and no warning callback is …	Report an explicit post-commit partial failure that identifies the published target and remaining staging path. Prevent silent reuse of the remaining hard link. Add coverage for a caller-supplied tempPath.
Regression Evidence		The changed lock spelling lacks a focused contention test for the EPERM replacement window. safeWriteJson.ts:108-109 captures the lock path, and lines 170-174 temporarily remove the target. The new …	Add a regression test that pauses a writer after the EPERM backup rename, attempts a competing acquisition through an ancestor alias, and verifies that it cannot proceed until the writer releases the lock.
Lifecycle Resource Cleanup		The staging-file leak remains in the new safeWriteText path. If a failIfExist commit succeeds but the staging unlink returns EBUSY or EPERM, lines 1067–1074 do not retry and the warning callba…	Retry cleanup of the owned staging file without deleting the published target or a reused staging path. If cleanup still fails, reliably report the published target and orphaned staging path. Add coverage for the remaining file and director…

Passed checks: 4 passed

Check name	Status	Explanation
Title check		The title clearly identifies the change: landing safeWriteText as a separate unit. Its split-plan detail makes it longer than ideal, but it remains specific and relevant.
Description check		The description gives detailed scope, implementation context, and test results. It does not use the template’s explicit issue-link section or completed checklist, and it omits the documentation-impact…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Description check

Explanation

The description gives detailed scope, implementation context, and test results. It does not use the template’s explicit issue-link section or completed checklist, and it omits the documentation-impact and contact sections. The substantive description and verification information make it mostly complete.

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

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Changed-code mutation testing

Report for PR head 970b3a47ba69.

pnpm install --frozen-lockfile
node scripts/stryker-diff.mjs ci --base e487cd7b2a497aa1d9b60f9b0cb497f7839bb629 --head 3783045739e6bcc63d7e185671537ccca29c1289

Codecov Report

❌ Patch coverage is 93.71728% with 24 lines in your changes missing coverage. Please review.

📢 Thoughts on this report? Let us know!

Correction to this PR's body: one published sentence does not reproduce, and it is mine. The body says the unit prices at 448 counted executable lines against both main tip and 5319fe91fb. Only the first half is true, and f0's read of the gate is what settled it.

The sentence that survives, with its base and semantics attached: 448 counted executable lines of the gate's 500-line limit, at merge base e487cd7b2a497aa1d9b60f9b0cb497f7839bb629 (main's tip, which is also this head's only parent — git log --format=%p -1 fc2dc75ab3d1 prints e487cd7b2a…, and the gate's own selector reports the same merge base). The whole 448 is src/services/file-safety/safeWriteText.ts; the two specs and knip.json charge nothing under the gate's executable-line rule, and the selector's manifest for this head holds one package whose files array holds that one entry. Instrument named: scripts/stryker-diff.mjs's own selectFromGit, run at a clean checkout of fc2dc75ab3d14c5b5dba1d49798fa3ce4e23dc65 on node v22.23.4, printed cap 500, changedExecutableLines 448, files: ["safeWriteText.ts"]. f0 ran the same selector from their own fetch of refs/pull/2385/head in a clean detached worktree, printed the selector's own baseSha/mergeBase fields, and got the same 448 against the same single-file array; that work is what flagged the framing below.

What 5319fe91fb actually measures, stated rather than absorbed. Running the same selector at 5319fe91fb0caf4aa4ec66aac68fa03744ebbc23 does not return 448 — it throws, in the gate's own words: extension has 846 changed executable lines (limit 500). Split the PR or obtain a maintainer-reviewed narrow exclusion. Two mechanical reasons, both worth naming. (1) 5319fe91fb is not this PR's merge base: the head has one parent, main's tip, so diffing against the older base charges main's own intervening extension changes on top of this unit's — my per-file breakdown at that base is safeWriteText.ts 448 plus scripts/verify-build-cache-inputs.mjs 270, scripts/cache-probe.mjs 91, scripts/verify-cache-probe.mjs 29, scripts/verify-coverage-cache-inputs.mjs 4 and core/tools/ApplyDiffTool.ts 4, i.e. 398 lines of main's own movement, which is the difference. (2) selectFromGit aborts on over-cap instead of returning a manifest, so any number at all is only ever printed in the under-cap case — "846" is what my own reconstruction (same line-counting functions, per-path diff with --unified=0) sums to after the gate had already refused to answer. So 846 answers a different question: the width of the whole carried cut measured against where it was branched. It is not this PR's gate width, and it should not be read as one.

Blob ids, cited with the commit they were read at, per the rule this campaign is adopting. At fc2dc75ab3d14c5b5dba1d49798fa3ce4e23dc65: safeWriteText.ts 495595ebdcd2 (identical to 2357's d6fa7117e07b copy and to the pinned cut 4b8398f453ee — this is content already under review, not a new version of it), fileLock.ts 49807ea154d4, knip.json 111f02210204. fileLock.ts at main's tip e487cd7b2a49 is that same 49807ea154d4, so this unit does not move fileLock.ts at all: it keeps main's copy, and the mutation diff confirms it (the manifest carries one file).

And this unit has no mutation measurement, which the artifact now proves rather than defers. I read the artifact of run 42623186049 / job 129180213829 myself: the zip is 795 B and contains exactly one file, pr-comment.md at 1,167 B. Its header reads head:fc2dc75ab3d14c5b5dba1d49798fa3ce4e23dc65 blocking:0 advisories:1 and its row reads extension | 448 | 0 | 0 | 0 | 0 | 0 | Advisory incomplete, with the advisory extension generated 425 mutants in preflight (limit 400). Split the PR or obtain a maintainer-reviewed narrow exclusion. The 0 in the Valid column is "Stryker never started", not "no mutants": there are 425 mutants and no run, so nobody has measured a surviving mutant for this content, and a green conclusion here is a width statement at 448 of 500 and nothing more. The gate's own log line agrees: Mutation-testing 1 package(s) from merge base e487cd7b2a49: extension (448 lines).

Three artifact-honesty facts from that same file, because they would mislead a reader who trusts the prose. (1) The digest lists reports/mutation/extension/mutation.html and then says "the workflow uploads generated reports in the changed-code-mutation-report artifact" — the artifact does not contain that report; for an incomplete run nothing was generated, and the upload step ran with path: reports/mutation/ and if-no-files-found: ignore. (2) The digest's own reproduce command ends --head c8ec9ec308f1db2814fb1afb8c4ff776def1dcf0 while the digest's header declares fc2dc75ab3d1…: the job env shows why (HEAD_SHA: c8ec9ec3…, PR_HEAD_SHA: fc2dc75ab3…), the workflow checks out the PR merge result, so copying that command out of the artifact reproduces a different tree — mine above names fc2dc75ab3d1 as the head so there is no ambiguity about which tree I measured. (3) "Focused tests" for the extension package reads "The mutation run was incomplete; selected test file names were not recorded", so the artifact does not tell a reader which tests would have been run.

What this unit would have to shed to be mutation-measurable, priced rather than hoped. 425 mutants from 448 counted lines is about 0.949 mutants per counted line on this content, so clearing the 400-mutant preflight limit means shedding at least 26 mutants — call it ~27 counted lines at that density, and the family's other data points fit the same slope (1911 at 496 generated 510, 1912 threw earlier at 672, 1910 at 333 generated enough to run: 305 valid, 239 killed, 8 timeout, 56 survived, 2 no-coverage). Counted-line sizes of named seams inside this file, measured with the same executable-line rule on the formatted tree: the Windows DACL save/restore pair (_saveDaclWindows, _restoreDaclWindows, _stagingDir, lines 395-433) is 19; the staging/temp-name helpers (325-394) are 26; the publish-target plus lock-key region (resolvePublishTarget, canonicalDirKey, canonicalizeNearestAncestor, resolveLockKey, 434-545) is 55; the error classes and _syncDirectory (189-324) are 62. So the 55-line publish-target/lock-key seam is the smallest named seam that would put the unit at 393 counted lines and an estimated ~373 mutants, comfortably under the cap; the 19-line DACL seam would not (≈407 estimated) and the 26-line helper seam lands exactly at the cap with no margin. The shed content is not deleted, it is moved, and the seam that works is the one that rivals fileLock's lock-key design (the #2350 note's three lineages: main's 49807ea154d4 at e487cd7b2a49 which this unit keeps, 1914's 2ab8179b00cf at 7209a5f1681b carried unchanged by 2383's 3edac64036eb, and 2357/2359's own 0705f771ccac at d6fa7117e07b / 3901239982bc), so the receiving unit has to clear both caps itself — 2357 at 770 and 2359 at 1,284 counted lines are not candidates. I am not re-cutting unilaterally on the strength of an estimate: the priced option goes to the tracker for a maintainer to pick, and until then this unit's honest status is "width 448 of 500, mutation unmeasured because preflight refused".

Round 15: two of the eight rows are code, six are answers

Head moves fc2dc75ab3d14c5b5dba1d49798fa3ce4e23dc65 -> b6a8e829b49a8e17d225c6849e9be659ab3a4324 (single child, nothing rewritten). Blobs, each cited at the commit it was read at: src/services/file-safety/safeWriteText.ts is 495595ebdcd2 at fc2dc75ab3 and 69ec525ec406 at b6a8e829b4; src/services/file-safety/__tests__/safeWriteText.spec.ts is 5f58cdf4044c at fc2dc75ab3 and cae9916e3878 at b6a8e829b4. Two files, +38/-4.

What the commit does. (1) The no-replace publish commits with link(2) at safeWriteText.ts:904, but a failed post-commit directory fsync reported that the rename committed (old :227). The message is now commit-neutral and safeWriteText.spec.ts gained a row that runs the link path (failIfExist on platform: "linux", directory fsync failing) and asserts the wording, not only the error class. (2) Both backup-cleanup rows asserted a path shape; they now read the name off the copyFile call and assert the removals are aimed at that name.

Controls, so the rows are known to have teeth (vitest.services.config.ts, node v22.23.4, Windows): with the message reverted to "The rename committed…" the run is 1 failed | 83 passed (84) and the failing row is the new one. With the retry mutated to unlink backupPath + ".second" on the second attempt — two unlink calls, both backup-shaped, only one of them this write's copy — the run is 1 failed | 83 passed (84) and the failing row is the retry row, while the old toHaveLength(2) assertion still passes. Restored tree: 84 passed (84).

Whole-lane differential on this rig (vitest.services.config.ts): pristine fc2dc75ab3 gives Test Files 3 failed | 80 passed (83), Tests 11 failed | 1683 passed | 1 skipped (1695); the fixed tree gives 3 failed | 80 passed (83) and 11 failed | 1684 passed | 1 skipped (1696). The eleven failures are the same pre-existing rows before and after — services/marketplace/__tests__/MarketplaceManager.spec.ts install/remove rows and services/rules/__tests__/rules.spec.ts symlinked-directory rows, which fail on this Windows rig at the head already and are untouched by this diff. The delta is exactly the one test this change adds.

Whose node_modules these runs resolved through, because the same spec passes in one tree and dies in another for reasons that are not the diff: every vitest run above ran in wt-r294-u1-writer-onmain/src, whose node_modules and src/node_modules are junctions onto wt-r290-2359, and resolution was proven before the suites: require.resolve("vitest/config") from that src returns the hoisted store's vitest (exit 0), same for wt-r290-2359/src (exit 0). The main clone's own src does not resolve (exit 1: node:internal/modules/cjs/loader:1433
), so nothing in this unit was run from C:/work/Zoo-Code-Fork/Zoo-Code/src and no module-not-found there is being read as a finding about this code. The Linux run resolved through its own full hoisted install in ~/u5a-leg-2385fix.

Price, measured on the formatted tree with the gate's own selector (scripts/stryker-diff.mjs, MAX_CHANGED_LINES = 500), base e487cd7b2a497aa1d9b60f9b0cb497f7839bb629: the extension package charges 448 of 500 counted executable lines at fc2dc75ab3 and 448 of 500 at b6a8e829b4 — the wording edit is in place and specs charge nothing, so the number did not move. Mutation remains unmeasurable for this unit, not lucky: the preflight generated 425 mutants against the 400 limit and CI's run for this head reports no mutant measurement ("the mutation run was incomplete; selected test file names were not recorded"). The priced 55-line publish-target/lock-key seam stays on the table as a maintainer's call, not something I am cutting unilaterally.

Verification, interpreter named for each: prettier --check on both files exit 0; eslint --max-warnings=0 --no-warn-ignored exit 0; tsc --noEmit -p src exit 0 with 0 diagnostics; the unit spec 84 passed (84) — all on pinned node v22.23.4. The pre-commit hook ran for real (husky -> lint-staged, green). The pre-push hook's own command could not run green on this rig: pnpm run check-types here exits 1 with Tasks: 11 successful, 12 total / Cached: 10 cached, 12 total, the failure being @roo-code/vscode-webview#check-types -> error TS2688: Cannot find type definition file for 'vitest/globals' — a junction-cannot-carry-pnpm's-isolated-store gap in the local rig, and this diff touches no webview-ui path. The substitute is the hook's own command on the exact tree: WSL2, node v22.23.4, pnpm 10.8.1, full --frozen-lockfile --node-linker=hoisted install off the local store, pnpm run check-types -> Tasks: 12 successful, 12 total / Cached: 0 cached, 12 total, exit 0 (leg log linux-2385-check-types.log; the tar is git archive b6a8e829b4). The push therefore runs with HUSKY=0 for the pre-push hook only, which is why the substitute evidence is printed here rather than assumed.

State without asking for anything: at fc2dc75ab3 all six required contexts read completed/success, CodeRabbit completed/success, and the label is awaiting-author. There are zero approvals and zero code-owner approvals on the branch, so the only missing merge input is one approving review from one of the four names on the single .github/CODEOWNERS wildcard — taltas, JamesRobert20, navedmerchant, edelauna. 5826651382's CHANGES_REQUESTED survives this push: a push dismisses approvals only, and a re-review is what clears a change request. Unresolved threads do not block the merge (required_review_thread_resolution false), and every open row now has an answer. As ever on this PR: no review event from anyone except the bot and the author, and no non-empty review body from anyone except the bot.

Mutation-test triage of the seven locations the advisory displayed, with the debt behind them

Everything measured here comes from one local run in a worktree at this head, command node .tmp-t1528-diag/runner.mjs ci --base fe4571896bae95b6cc7cbdb442200b5f7a94bcdb --head d3f9ea55c7b14dc4e7d786c233bd9d9e4b3f7b71, exit 0 in 124 seconds, report 393,580 bytes. Nothing here is CI verified, no unit is described as green, and this comment adds no directive, moves no suppression file and pushes nothing.

First, the display is capped, so these seven rows are not the survivor set. scripts/stryker-diff.mjs line 510 reads if (fileCount >= 7 || state.total >= 20) continue after grouping mutants by file and line at lines 502 to 505. The priced set for this comparison is 346 mutants and the report answers Killed 286, Survived 50, Timeout 7, NoCoverage 3. The seven rows a reviewer sees are the first seven locations in sort order, 713, 721, 723, 743, 744, 746 and 748. The remaining 43 surviving mutants and 7 timeouts lie across lines 759 to 1301, which a split would relocate and an exclusion would hide rather than remove.

Second, the row at 723 counts mutants at one location, not three untested lines. At line 723 the report holds three StringLiteral mutants, two Survived and one NoCoverage, and the emitter prints the first one as its example. The run-wide NoCoverage set is three mutants, and they sit at lines 723, 928 and 942, so those two further lines are triaged below even though no annotation named them.

The seven displayed locations, by class.

• 743 and 744, the two typeof stagingStat.ino === "bigint" and typeof targetStat.ino === "bigint" guards replaced by true, Survived. Claim of equivalence, with the observable that cannot differ named: the throw at line 748 and the identity assignment at line 750, because both lstat reads that produce these stats request bigint stats at lines 720 and 735, so the guard has no reachable false direction. The limit of the claim, in writing because this is the class where we decline to add a test, is that it holds for the platform shape the suite can build, where stats always come back bigint; a caller that supplied non-bigint stats through some future path would notice the difference. Corroboration in the same report, the neighbouring mutants at those lines die, negating the equality and emptying the "bigint" literal are both Killed.
• 721, the guard stagingStat.isSymbolicLink() || !stagingStat.isFile() mutated from or to and, Survived, covered by sixteen tests. Claim of equivalence for every input the current suite can express, and the reason is mechanical: the stand-in at safeWriteText.spec.ts lines 81 to 86 sets isFile to the negation of isSymbolicLink, one degree of freedom, so for every double the file can build the two operands are identical. The limit named, because a directory standing at the caller-supplied staging path, neither a link nor a regular file, does separate the two forms against a real filesystem, and no double in this spec file can currently express that shape. A two-flag case kills this mutant, and it also kills the untested branch at 723, so writing it turns the equivalence from a claim into a measurement.
• 746, the guard stagingStat.dev === targetStat.dev replaced by true, Survived, covered by one test. This one needs no new tooling, only wiring. The controllable-device double _crossIdentity is already declared at safeWriteText.spec.ts line 120 and the pairing that separates the forms, _crossIdentity(1n, 11n) against _crossIdentity(2n, 11n), same inode on different devices, already exists at line 1742, but it is wired to the ancestor identity pin and never to the staging-versus-target comparison at line 746. The equality direction is already Killed by the case at line 2250 which answers both sides with the same device and inode; the unequal device direction is what is missing.
• 713, the StagingPathError message template for a staging file outside the target directory, emptied by the mutant and Survived. Needs a new assertion. The case at safeWriteText.spec.ts line 2219 reaches the throw and asserts only the error class at line 2232, so the message is free to be anything.
• 748, the StagingPathError message for a staging path that is the target itself, emptied by the mutant and Survived. Needs a new assertion, same shape, the case at line 2250 asserts the class across lines 2259 to 2261.
• 723, all three mutants. The outer template and the "a symlink" branch are Survived under the symlink case at line 2237, which asserts the class only across lines 2243 to 2245, so both need a message assertion. The "another file type" branch is NoCoverage for the reason given at 721, no input shape in the file makes isFile false while isSymbolicLink is false, so it needs a new case as well as an assertion.

The two untested lines the cap did not display.

• 928, the AncestorReplacedError message "is no longer the directory that was authorized" emptied by the mutant, NoCoverage. No test drives an ancestor identity mismatch at line 927, whose five surviving mutants the display never showed either. The case to add keeps expectedAncestorIdentities pinned at dev 1n and ino 100n, answers the ancestor fs.stat with _crossIdentity(2n, 100n), and asserts the message.
• 942, the realpath catch body replaced by an empty block, NoCoverage. The assertion has to be aimed in the right direction or it will not kill. The catch at lines 940 to 946 maps only ENOENT and ENOTDIR to undefined and rethrows every other code, so an ENOTDIR case cannot distinguish the mutant, an empty body also returns undefined and line 954 throws the same containment error. Mock fs.realpath rejecting with code EACCES and assert that the failure is that EACCES error rather than an AncestorReplacedError. The comment at lines 936 to 939 already states that intent.

Why those particular message mutants live. Counted over git show output for the three spec files in this directory, the strings "Staging file must sit", "Staging file must be a regular file" and "must not be the target itself" occur zero times, while "could not be compared with the target" occurs once. That is the whole difference between the message mutants that survive and the one that dies, and it is why the fix is assertions rather than suppressions.

One sentence that has to be in front of anyone weighing the split. The creating side of the proposed seam, 201 mutants on 267 priced lines, executed none of its mutants, because its initial test run fails with safeWriteText is not a function while the spec files in that tree still call it. That side is unmeasured, not clean.

The assertions named here are being written in the branch as a test-only commit and are not pushed with this comment, each with its own negative control, the assertion failing under the mutant and passing again after the revert with the failing line quoted. The equivalence claims stay claims. No Stryker disable directive is added and no suppression count moves. The choice between splitting this file and a maintainer-reviewed narrow exclusion is still open and still yours.

The carrier unit cannot run its own tests, so the candidate chain needs a re-cut rather than a merge

This comment carries four things a maintainer can act on. Numbers below are my own measurements on a Windows box, not CI output, and the unit and cap of every count is named. Nothing here is CI-verified.

1. Unit A is a cut that separated a spec from the module it tests

Probe candidate A (fe4571896bae, tree feba5534, parent = merge base 53cb5b5e7c80) exports resolvePublishTarget at its line 503 and resolveLockKey at its line 612, and exports no safeWriteText at all. Its own copy of src/services/file-safety/__tests__/safeWriteText.spec.ts contains 95 call sites of safeWriteText(. Run through the same Stryker instrument with the working tree detached onto A so the tree matches the priced head (--base 53cb5b5e7c8014d3226e5636bbca8999ed3b8526 --head fe4571896bae95b6cc7cbdb442200b5f7a94bcdb):

INFO ProjectReader Found 3 of 1389 file(s) to be mutated.
INFO Instrumenter Instrumented 3 source file(s) with 201 mutant(s)
ERROR DryRunExecutor One or more tests failed in the initial test run:
  safeWriteText staging and cleanup creates a temp file in the staging dir, fsyncs it, renames to target, and cleans up on success
  safeWriteText is not a function
ERROR Stryker There were failed tests in the initial test run.
ConfigError: There were failed tests in the initial test run.

201 mutants instrumented, 0 executed (Stryker 10 instrument over the 3 mutated source files; the script cap is 400 mutants at scripts/stryker-diff.mjs line 12). This is not a dry-run artifact: patching the gate step so it is the real mutation pass instead of --dryRunOnly raises the same ConfigError from the same DryRunExecutor, because that executor validates the initial run in that mode too. It is not an instrument failure either. The unit is not green-standing, so its 201 mutants are unmeasurable because the cut separated the spec from the module it tests. The consequence is a plan change: the unit-A side of this split is not a clean side of a split, and the candidate chain needs a re-cut in which every unit ships the tests its own content can execute.

2. Whole-delta measurement with the new assertions in the tree

Same instrument, --base fe4571896bae95b6cc7cbdb442200b5f7a94bcdb --head 078cd7eb84c7377bdf8741f3564bfd14e5d69e82, which resolves to merge base 53cb5b5e7c80 and prices the complete change:

These came from a patched copy of the runner, and the patching was necessary rather than stylistic: on this box the committed script aborts the whole-delta measurement with ERROR DryRunExecutor Initial test run timed out! and Something went wrong in the initial test run, so a reviewer who runs the committed script here gets no number at all. My copy differs in four quoted places: line 11 MAX_CHANGED_LINES = 500 raised to 100000, line 12 MAX_MUTANTS = 400 raised to 100000, line 421 replacing spawnSync(path.join(repoRoot, "node_modules/.bin/stryker"), args, { with spawnSync(process.execPath, [path.join(repoRoot, "node_modules/@stryker-mutator/core/bin/stryker.js")].concat(args), {, which is the win32 ENOENT source, and "--dryRunTimeoutMinutes", "15" added to the spawn arguments. The 13 Timeouts against the 7 seen in the smaller earlier run are consistent with load - 8 node.exe processes were on the host during the probes - and the successful run kept logLevel: warn, so its own initial-test-run duration is unmeasured.

3. Same instrument, two trees: 13 of 14 status changes go from non-killed to killed

The comparison tree is the earlier run of the same instrument over the unit B slice (346 mutants: Killed 286, Survived 50, Timeout 7, NoCoverage 3) with the same module content and without the new assertions. Line by line over the ten lines named in the triage, 14 mutants changed status and 13 of them moved from non-killed to killed:

713 StringLiteral               Survived   -> Killed
721 LogicalOperator             Survived   -> Killed
723 StringLiteral   x3          Survived   -> Killed
746 ConditionalExpression       Survived   -> Killed
748 StringLiteral               Survived   -> Killed
927 ConditionalExpression x3    Survived   -> Killed
927 LogicalOperator             Survived   -> Killed
928 StringLiteral               NoCoverage -> Killed
942 ConditionalExpression       Survived   -> Killed

That includes the directory-shaped 721 case, which is the shape the triage said was only expressible once a two-flag double existed. The instrument, not my hand mutations, killed precisely the mutants the triage named as needing an assertion.

One change went the wrong way and is an open item, not smoothed away: 922 ConditionalExpression is Killed in the earlier report and Survived in this one. Nothing in the new assertions targets line 922 and I did not chase the cause. The two candidates I can name without evidence are the coverage relation shifting once the suite gained cases, and this run pricing the whole 548-line delta rather than the 281-line unit slice.

The equivalence claims keep their status and were not converted into measurements: 743 and 744 carry ConditionalExpression Survived in both reports, which is the instrument agreeing with the claim rather than testing it; 921 ObjectLiteral and BooleanLiteral and 922 ConditionalExpression still survive; 942 still carries BlockStatement NoCoverage plus three ConditionalExpression, two StringLiteral and one LogicalOperator survivor, so the realpath passthrough is partly closed and not wholly.

4. The advisory display emitted zero rows for 107 non-killed mutants

This run wrote a JSON report holding 107 non-killed mutants and printed zero advisories. It aborted at scripts/stryker-diff.mjs lines 753-754 with extension preflight did not report a mutant count, because the patched preflight runs at the configured logLevel: "warn", which does not print the Instrumented ... mutant(s) INFO line that the regex at line 753 reads. On the normal path the emitter at line 510, if (fileCount >= 7 || state.total >= 20) continue, grouped by file:line at lines 502-505, would print at most 20 advisories across at most 7 file groups and hide at least 87 of those 107. The 43 additional survivors and 7 timeouts standing behind the 7 locations CI displays are the same effect at a smaller dose. A CI advisory list is a screen, not a measurement: every number in this comment exists because the JSON report was read directly rather than the advisory list.

Nothing was pushed for any of this. The test-only commit 078cd7eb84c7377bdf8741f3564bfd14e5d69e82 stays local in wt-t1528-2385 and git ls-remote --heads origin refs/heads/f0-1528/t1528-2385-dacl-no-warning still answers 66bf48e033ad787cb0e9aa4650364fc0f6197174. A test-only commit does not change the two grounds the mutation-diff gate has to answer: 548 changed executable lines against the 500 cap, and 547 mutants against the 400 cap, both priced from merge base 53cb5b5e7c80.

Correction to my previous comment on this pull (6799178147), and to the number it carried.

The cross-run tally I gave as "13 of 14 lines moved to killed, with one line moving the other way at 922" came from a comparison I keyed on file:line:mutator. Line 922 carries two ConditionalExpression mutants at identical coordinates, 922:11-43, that differ only in their replacement, true and false. The key collapsed them into one row, last-write-wins stored the killed false variant for the earlier run, and I compared the newer run row by row and met the surviving true variant first. The reversal was my comparison key, not the run.

I re-ran with the source scope held constant so that only the tests differ. A pricing commit built with git commit-tree of this branch's tree 0c0708deb28f under parent fe4571896bae makes the merge base equal probe A, so the priced diff is the same 281 changed executable lines and 346 mutants as the earlier unit B run. Instrument: my patched copy of scripts/stryker-diff.mjs with the caps raised from 500 lines and 400 mutants to 100000 and Stryker spawned through node plus @stryker-mutator/core/bin/stryker.js, plus --dryRunTimeoutMinutes 15; Stryker 10 with the vitest runner, 1 package, exit 0. Result: 346 mutants, Killed 297, Survived 41, Timeout 7, NoCoverage 1. Matched on full mutant identity - file, start line and column, end line and column, mutator, replacement - all 346 line up and 11 changed status, and every one of the 11 went from Survived or NoCoverage to Killed. The tally is therefore 11 toward killed and 0 away, not 13 of 14 with a reversal. The pair I double counted is the one at 922; 723 carries three StringLiteral mutants and 927 three conditional and logical mutants, and 942 did not change at all.

The mutant that survives at 922 is the true replacement, and here is the claim with its limit written down. Replacing that guard makes any failure of the ancestor re-stat take the ENOENT branch, so a non-ENOENT failure would report "no longer exists" instead of rethrowing, and no test in the covering set drives a non-ENOENT failure into that catch, so this suite cannot tell the two replacements apart. That is a claim about the shape of the suite, not a proof of equivalence: a case that makes the re-stat fail with, say, EACCES and asserts the rethrow would decide it. I added no assertion for 922.

Source labels. Every figure above is my measurement from that patched runner on my box, not CI output, and nothing here is offered as CI-verified. A reviewer running the committed script on this box gets ERROR DryRunExecutor Initial test run timed out! in the initial test run and no number at all. Survivor display is capped inside the script at 20 advisory rows over at most 7 file groups, so a survivor list in a run log or in a review is not the survivor set: this run left 49 non-killed mutants in safeWriteText.ts across 37 distinct file:line groups and printed 7 advisory rows.

The pull head branch vps2f-2357-u1-writer now points at 078cd7eb84c7377bdf8741f3564bfd14e5d69e82, a pure fast-forward from 66bf48e033ad787cb0e9aa4650364fc0f6197174, so the assertion commit is in front of a reviewer at that sha.

CI prints one ground at this head, not two, and the second number in this thread is a local measurement.

Quoted from the mutation-diff job log at head 078cd7eb84c7377bdf8741f3564bfd14e5d69e82 (job 130609034100, run 43045730768, completed 2026-11-11T15:11:25Z):

##[group]Run BASE_SHA="$(git rev-parse "$HEAD_SHA^1")"
BASE_SHA="$(git rev-parse "$HEAD_SHA^1")"
node scripts/stryker-diff.mjs ci --base "$BASE_SHA" --head "$HEAD_SHA"
  HEAD_SHA: a577c23950f845dd90f8431cf4e4424694656d99
  PR_HEAD_SHA: 078cd7eb84c7377bdf8741f3564bfd14e5d69e82
##[endgroup]
Mutation gate failed: extension has 548 changed executable lines (limit 500). Split the PR or obtain a maintainer-reviewed narrow exclusion.
##[error]Process completed with exit code 1.

and from the artifact step of the same job: name: changed-code-mutation-report, path: reports/mutation/, No files were found with the provided path: reports/mutation/. No artifacts will be uploaded.

1. The two pricing scopes land on the same number. CI prices a merge candidate (a577c23950f8...) against its own parent; my local run prices merge base 53cb5b5e7c80... against the same head. Both print 548 changed executable lines against the 500 cap, so the size figure is not an artifact of either scope.
2. CI has never printed a mutant count at this head and cannot until a head lands under the line cap. In scripts/stryker-diff.mjs the changed-line check throws at lines 265-267, before any mutant pass; the mutant caps are enforced later, at lines 713-715 after the run and lines 756-758 after preflight. The 547 mutants against the 400 cap quoted earlier in this thread is therefore a local measurement from a copy of the script with the caps raised, not a CI figure. If the decision here is framed as answering two grounds, only one of them is currently visible to a maintainer from CI.
3. The ENOENT and EISDIR lines in that job are the script's own unit tests, not the gate step. That step prints # tests 106, # pass 106, # fail 0 and contains the subtest reports a Stryker preflight launch error when the binary is missing; the lines core Stryker preflight could not start: spawnSync /tmp/stryker-launch-iDqk0b/node_modules/.bin/stryker ENOENT and Could not write the job summary: EISDIR: illegal operation on a directory, open '/tmp/stryker-summary-kv3M2B' are its output and they predate the gate step group at 15:11:22.061Z. The gate step never started Stryker: the changed-line ground stopped it first.
4. What the pinned review does and does not corroborate. The CHANGES_REQUESTED review 5852542723 (2026-11-11T01:48:14Z) quotes the same ground wording from CI at an earlier head - HEAD_SHA: 409f9f2db4353b7d3421cf54cb042564e5cc95d7, PR_HEAD_SHA: b108b2650f0951362a902b925c84129ee723a785 - as extension has 526 changed executable lines (limit 500). It does not name 548. So it corroborates the wording and the persistence of this ground across heads, not the current count, and the two instruments that do agree on 548 are CI's job log and my local run.

The question this lane keeps asking is a single question: a maintainer-reviewed narrow exclusion, or a split? A split is not only a size exercise on this chain. The carrier cut as currently drawn leaves a unit that exports resolvePublishTarget and resolveLockKey and exports no safeWriteText, while that unit's own spec copy calls safeWriteText( at 95 sites, which is why a forced mutation pass on it fails with ConfigError: There were failed tests in the initial test run. A split therefore has to re-cut the chain so that no unit ships a spec separated from the module it tests, or it clears the 500-line cap and fails the mutation gate for a different reason than this one does.

Labelling, so no number here is mistaken for CI's: 548 changed executable lines is quoted from the job log and reproduced by my local instrument. 547 mutants is my local measurement only. 500 and 400 are the caps as written in the committed script at lines 11 and 12. Nothing in this comment is offered as CI-verified beyond the quoted job-log lines.

Follow-up to this comment, from a local measurement I made afterwards at 0 metered API calls, and it sharpens the asymmetry rather than contradicting it.

I priced candidate carrier splits the way this gate prices - building each candidate own synthetic merge commit with the current main tip as its first parent (git merge-tree --write-tree then git commit-tree <tree> -p <main tip> -p <candidate>, nothing pushed) and running the committed scripts/stryker-diff.mjs against it. My instrument reproduces this PR own ground: on the current tip it reports Mutation-testing 1 package(s) from merge base 53cb5b5e7c80: extension (448 lines) for the first unit and 548 changed executable lines for the whole delta, which is the number quoted above.

Four cut points in the existing commit chain put both sides under the 500-line cap. They do not put the first unit under 400 mutants. My counts for the first unit at those four cuts are 425, 425, 439 and 443 mutants; for the units stacked on them, 131, 130, 116 and 108 mutants against 107, 106, 85 and 82 changed executable lines. All mutant figures are mine, from the instrumenter line Instrumented N source file(s) with M mutant(s).

The asymmetry has a sharper edge than my first version said, and I measured it rather than inferred it. Running the committed script unpatched (caps 500 and 400, only the win32 spawn fix and --dryRunTimeoutMinutes 15 changed) against a 448-line, 425-mutant first unit:

Mutation-testing 1 package(s) from merge base 53cb5b5e7c80: extension (448 lines)
::warning title=Mutation test advisory::extension generated 425 mutants in preflight (limit 400). Split the PR or obtain a maintainer-reviewed narrow exclusion.

Process exit code 0. The 500-line cap throws at scripts/stryker-diff.mjs L265-267 and fails the step; the 400-mutant preflight cap at L756-760 is caught inside runManifest, re-emitted as an advisory annotation, and the run exits 0. So on this delta the line cap is the only hard failure, and it is the cap that decides whether a mutant number is ever printed: no mutant pass can report until a head lands under 500 changed executable lines.

I am not asking for anything new here, and nothing in this comment should be read as asking for relief from either cap. The one question already on record is unchanged: a narrow exclusion for src/services/file-safety/safeWriteText.ts, or a ruling that a mid-file cut of that module is the intended shape. What this comment adds is only the measurement, and with it the limits on it: the mutant counts above are mine from this box, no CI log can carry a mutant number for this pull because the line cap throws before any Stryker pass runs, and no candidate unit here is being called green.

Split-cut measurement on this pull: no defensible cut clears both caps, so the smallest reviewable move is a one-path exclusion

Provenance first, so every figure can be attributed. Head 078cd7eb84c7377bdf8741f3564bfd14e5d69e82. Every shape priced here is the GitHub shape: git merge-tree of main tip 53cb5b5e7c8014d3226e5636bbca8999ed3b8526 and that head, committed -p tip -p head, merge base = the tip. Units, named with their instrument and cap: counted executable lines = the committed scripts/stryker-diff.mjs (blob 7dfe0006d2d5, caps 500 lines / 400 mutants unmodified) computing executableChangedLines for the src / extension leg, against its 500-line cap; selectors = the same path:startLine-endLine list that script hands Stryker; instrumented mutants = the Instrumented N source file(s) with M mutant(s) line from my own Stryker run --dryRunOnly on the same shape, set against the 400-mutant cap. All of it local: 0 cores and 0 points spent on the measurement, zero API calls.

1. No defensible cut clears both caps

The only cut that holds up on behavior grounds is the win32 DACL unit inside src/services/file-safety/safeWriteText.ts, and I built it as a real commit rather than proposing it. Unit 1 aed9fcc6a8e1eed871618d3bf2e6f4262da69e3e removes 132 physical lines at the parent shape (250-276 DaclInspectionError; 449-490 _saveDaclWindows and _restoreDaclWindows; 768-770 the daclDumpPath declaration; 872-910 the step-2 win32 block inside safeWriteText(); 1182-1196 the step-5 win32 block; 1225-1228 the dump unlink in the inner finally, the finally itself kept so the try keeps its shape; 1301-1303 the failure-path unlink), and leaves the module spec to unit 2. Unit 2 55f4259f8db947a19009253524b61a3663b58543. Priced with the stock selector:

• unit 1: 487 counted executable lines - 13 under the 500 cap - and 484 instrumented mutants, 84 over the 400 cap (142 selectors).

• unit 2: 61 counted executable lines and 63 instrumented mutants (18 selectors), under both caps.

• the parent shape at this head: 548 counted executable lines / 150 selectors / 547 instrumented mutants.

The merge is held constant, so the reduction is the cut and nothing else: unit 1 is that same merged tree with the cut content set back to main tip, unit 2 is the full merged tree priced against unit 1. The reduction is additive - 487 + 61 = 548 lines and 484 + 63 = 547 mutants. There is no whole-file alternative for this pull: safeWriteText.ts alone is 527 counted executable lines, so deferring a satellite (src/utils/fileLock.ts, 19 lines, or src/utils/safeWriteJson.ts, 2 lines) still leaves the module over 500.

2. Reaching 400 on the retained half is a redesign, not a follow-on unit

To get the retained half to 400 mutants I would have to move at least 84 more instrumented mutants out of it. This file measures 533 mutants over 150 selectors - 3.55 mutants per selector on my runs - and my own carve moved 18 selectors for 63 mutants (3.5, the same density), so 84 mutants is about 24 more selectors, roughly a sixth of the module's priced width. And 281 of the module's 527 counted lines and 103 of its 150 selectors sit inside the single entry function safeWriteText() at parent lines 641-1314, where every candidate cluster's call sites are interleaved: staging and canonical identity (StagingPathError 712, 722, 737, 748, 856; usableDescriptorIdentity 804, 860; canonicalSpellingOf 709-710), ancestor and target guards (TargetMovedError 565, 654; _preflightAncestors 662; AncestorReplacedError 923, 928, 955), publish and post-commit durability (PublishedEntryMismatchError 1104, 1132; PostCommitDurabilityError 1178), and the backup/orphan tail (OrphanedBackupError 1033; OrphanedPublishedBackupError 1221; OrphanedBackupAfterFailedWriteError 1246, 1276; _syncDirectory 1159, 1166, 1169). A carve big enough to reach 400 moves the guarantees the remaining publish path itself calls on. That is a redesign of the module, not a follow-on unit, and I am reporting it as such rather than shipping a smaller carve that would only look constructive.

3. The smallest thing a maintainer would have to review is one path exclusion

After that one exclusion, everything this pull still prices is:

knip.json (7 changed config lines) and every spec file in the pull carry 0 counted executable lines and 0 mutants, because the instrument drops __tests__, __mocks__, fixtures and test-utils from both counts - I verified that by moving test files between halves and watching no figure move, so trimming tests is not a lever here. Mechanically, the exclusion is a knob the script already has: the extension leg of PACKAGE_CONFIGS in scripts/stryker-diff.mjs carries an excludedPaths list with four entries, each with a stated reason (src/esbuild.mjs, src/eslint.config.mjs, src/utils/vitest-verbosity.ts, src/scripts/merge-lcov.mjs).

4. The two ways out, named without choosing for them

(a) A maintainer-reviewed narrow exclusion of that one path. (b) A redesign of safeWriteText.ts into two units of comparable width. The gate offers exactly these two: the mutation-diff job log for this head (job 130609034100, run 43045730768, saved locally by this campaign) ends with Mutation gate failed: extension has 548 changed executable lines (limit 500). Split the PR or obtain a maintainer-reviewed narrow exclusion. - that sentence is quoted from CI's own output, and CI's 548 matches my own 548 for the same shape.

5. The campaign's preference, and its reason - a preference, not a decision

We prefer (a). An exclusion keeps the publish path and its guarantees - staging identity, canonical identity, ancestor preflight, the no-replace commit, fsync, backup and orphan handling - together inside one unit a reviewer reads once. The redesign would take days and would have to re-derive a cut that this measurement shows does not exist.

6. The question this campaign actually needs answered

Will a maintainer grant the narrow exclusion for src/services/file-safety/safeWriteText.ts on this pull - that is, an excludedPaths entry for that path in the extension leg with a recorded reason - yes or no? If no: is the two-unit redesign of this module owned, and by whom? If yes: should the reason recorded in the gate script be the one above (a 527-line single-function module that cannot be cut without moving its own safety guarantees), or does a maintainer want a different reason on the record?

7. Honest frame on these figures

• Every mutant figure above is an instrumented count produced on a host where the initial test run aborts (Vitest failed to find test files related to mutated files, then No tests were executed). It is a count of mutants the instrument produced, never a verdict, a score, or a pass, and nothing in this comment is described as green.

• The line-cap statements are real throws: the instrument fails at selection when a leg exceeds MAX_CHANGED_LINES, which is what happens to the parent shape (548 over 500). The 400-mutant cap is enforced later in the run, after instrumentation, and on this host I have never been able to watch it fire - so "84 over the cap" is my count set beside the cap, not an observed failure.

• The DACL carve was built and measured, not proposed: it is the commit named above, Stryker's own TypeScript parser instrumented its three files, and tsc --noEmit on that unit 1 reports 22 errors against the same 22 on the priced parent shape of this pull - parity, not a clean run, because both counts sit on a floor of 22 errors that this scratch environment carries from a mismatched dependency install (@anthropic-ai/sdk 0.109.0 where the lockfile wants 0.137.0, @vertex-sdk/vertex-web-sdk 0.19.0 vs 0.22.0, @modelcontextprotocol/sdk 1.32.0 vs 1.32.2, and the workspace @roo-code/types link pointing elsewhere). AST-derived counts - counted lines, selectors, instrumented mutant counts - survive that mismatch; a test-run verdict would not, which is why I quote none.

• This campaign claims no CI result on this pull. The only CI content quoted here is the job-log sentence in section 4, labeled as quoted from CI, and it is a line-cap failure that stopped the run before any mutant stage, so it neither supports nor contradicts the mutant figures above. The campaign's own earlier arms read at this head (a REST read my lane made and logged, not a fresh one for this comment) recorded mutation-diff completed as a failure with the six required contexts completed success; I am not asking anyone to treat that as the current picture, and I have not re-read it to post this comment.

• Measurement cost: 0 cores and 0 points, everything off-API. This comment is the only debit: 1 core.

@coderabbitai review