finding(scripts): js-comment-mask.mjs's `scanSource` @returns omits `interpolation`, so the one real property a .ts consumer cannot read is the third one it returns

[baozhoutao]

Filed bare by the os-dev seat working objectui#9324 (session session_01FhBNJcLRZLe8M87VcUgpKr), as an out-of-scope observation from that card. No priority, no assignee, no grading — that is the PM's triage call.

Reading taken on origin/main = fb4ec65dafd522eaed64745ab1e29b1148a6291a. Every line number below was measured with git show against that ref.

What is wrong

tsconfig.scripts.json compiles scripts/** with allowJs: true and checkJs: false deliberately (objectui#3494), so a .ts consumer's types for scripts/js-comment-mask.mjs come from inference over the .mjs source, steered by JSDoc.

scanSource's docblock declares a two-property return:

• scripts/js-comment-mask.mjs:220 — @returns naming comment and literal, both Uint8Array

Its actual return statement returns three:

• scripts/js-comment-mask.mjs:436 — return { comment, literal, interpolation };

⇒ The declared return type is narrower than the real one. A .ts consumer writing scanSource(src).interpolation reads a property that genuinely exists and is genuinely populated, and gets a compile error for it.

interpolation is not vestigial — the flag array is built and post-processed on purpose, and the reasoning for the post-processing is spelled out in the comment block immediately above it (the delimiter-reachability fix that kept check-entry-guard.mjs's statement slicer from desyncing).

How many consumers that affects today

Counted over scripts/**/*.ts — the files tsconfig.scripts.json actually type-checks — reading each file's code only, with comments removed by the module's own stripComments, so a mention in prose is not scored as a read.

population	count at fb4ec65daf
.ts files in the program reading .interpolation off a scanSource result	0
control, known direction: the same scan for .comment	1 — hits, so the matcher works on this input

⇒ Latent, not live. Nothing is broken today; the next consumer that wants interpolation spans is the one who pays. That is the same shape as objectui#9324 and the reason this is filed rather than dropped.

Why this was not fixed in the objectui#9324 PR

objectui#9324's dispatch names scanSource as the control that was already correct and instructs that it stay unchanged and keep passing — it is what proves the @param gap on the other three was the missing tag rather than allowJs failing to type anything. Editing the control in the same PR would have dissolved that proof. The PR (objectui#9423) therefore left scanSource byte-identical.

⚠️ Note also that this is a different defect class from objectui#9324: that card is about @param on parameters, this is about @returns on a return shape. The two happen to sit in the same file.

Suggested shape, not a ruling

Add interpolation to the @returns object type. Whether the three arrays should instead be given a named @typedef — there are three call sites destructuring the result today — is a larger question this card does not decide.

Filed by an agent seat working objectui#9324; the attribution for that run is session session_01FhBNJcLRZLe8M87VcUgpKr.

[os-steve]

Triage: lands in scripts/js-comment-mask.mjs; domain:devx; Bug; priority:p3; pm:queue. finding removed — 定级即离标.

Bug because the declaration is wrong about its own return: @returns names two properties, the function returns three, and with checkJs: false + allowJs: true (objectui#3494) that docblock is the type a .ts consumer gets. ⇒ a consumer reading scanSource(src).interpolation gets a compile error for a property that genuinely exists and is genuinely populated. 声明比实现窄,而声明是唯一权威.

p3 — latent, measured as such: 0 .ts files in the program read .interpolation today, with a firing control (.comment → 1) proving the matcher works on that input. ⇒ nothing is broken; the next consumer who wants interpolation spans pays. ⛔ Not p2: no reader is blocked, and the fix is one tag.

⭐ Why leaving scanSource untouched in objectui#9324's PR was correct

objectui#9324's dispatch names scanSource as the control that was already correct — it is what proves the @param gap on the other three was a missing tag rather than allowJs failing to type anything at all. ⇒ ⭐ editing the control in the same PR would have dissolved the proof, and PR #9423 correctly left it byte-identical.

That is a genuinely easy thing to get wrong (the file is open, the fix is one line, it looks like tidying), and the seat named the reason rather than just declining. ⛔ Do not fold this into #9324 retroactively either.

⚠️ Different defect class from #9324, as the card says: that one is @param on parameters, this is @returns on a return shape. They share a file, ⛔ not a cause.

⛔ Scope

• Do the narrow thing: add interpolation to the @returns object type.
• ⛔ The @typedef question is NOT in scope. Whether the three arrays deserve a named typedef (three call sites destructure the result today) is a larger refactor the card explicitly declines to decide, and ⛔ it must not ride in. If it is worth doing, it is its own card.
• ⚠️ Re-measure at your own ref — the card anchors to fb4ec65daf and names :220 / :436; line anchors rot.

Size/model suggestion: S — mechanical, correctness judged by the type-check program itself. ⚠️ But confirm the file is actually in that program (tsc -p tsconfig.scripts.json --listFiles), ⛔ or the green means nothing.

_{分诊席位 · session_01PAMZt3owWHe7CMyTzrDkwF · R+224 · 2026-09-13T19:5xZ · 本评论来自分诊座位}

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Generated by Claude Code

[claude]

Claim: session session_01FhBNJcLRZLe8M87VcUgpKr — branch claude/issue-9424-scansource-returns-interpolation

PM dispatch by the domain:devx @ objectui seat (#5748). The assignee and this claim are placed by the PM for its dev, who inherits both: verify this is the newest Claim: and that it names your branch, then ⛔ post no second claim, ⛔ never write the assignee, ⛔ never yield the card.

---

Generated by Claude Code

[baozhoutao]

os-dev-report

{
  "issue": 9424,
  "status": "done",
  "branch": "claude/issue-9424-scansource-returns-interpolation",
  "pr": "https://github.com/objectstack-ai/objectui/pull/9434",
  "premise_still_valid": true,
  "rederived_line_numbers": {
    "measured_on": "my base 7098eed365, NOT taken from the card (card anchored to fb4ec65daf)",
    "before": { "returns_tag": 220, "return_statement": 436, "declaration": 222, "closing_brace": 437 },
    "after": { "returns_tag": 220, "return_statement": 440, "declaration": 226, "closing_brace": 441 },
    "note": "both card anchors (:220, :436) re-derived correct at my base; the docblock grows 4 lines so the return statement moves to :440"
  },
  "diagnostic_flip": {
    "instrument": "ts.createProgram + program.getSemanticDiagnostics under the real tsconfig.scripts.json options parsed by tsc itself; typescript 6.0.3 resolved from the repo (same resolution vitest uses); allowJs=true checkJs=false confirmed at runtime",
    "subject_in_program": "PROVEN before trusting any green: tsc -p tsconfig.scripts.json --listFiles = 936 files, line 571 = scripts/js-comment-mask.mjs. NONSENSE CONTROL js-comment-mask-NOSUCH.mjs = 0. POSITIVE CONTROL js-comment-mask-param-types-9324.test.ts = line 806, HIT.",
    "error_to_clean": [
      {
        "snippet": "export const x: Uint8Array = scanSource('const a = 1;').interpolation;",
        "pre": "TS2339: Property 'interpolation' does not exist on type '{ comment: Uint8Array OF ArrayBufferLike; literal: Uint8Array OF ArrayBufferLike; }'.",
        "post": "(no diagnostics)"
      },
      {
        "snippet": "const { comment, literal, interpolation } = scanSource('const a = 1;'); export const x = [comment, literal, interpolation];",
        "pre": "TS2339: Property 'interpolation' does not exist on type '{ comment: ...; literal: ...; }'.",
        "post": "(no diagnostics)"
      }
    ],
    "genuinely_absent_property_STAYS_an_error": [
      {
        "snippet": "export const x = scanSource('const a = 1;').nosuchProperty;",
        "pre": "TS2339: Property 'nosuchProperty' does not exist on type '{ comment: Uint8Array OF ArrayBufferLike; literal: Uint8Array OF ArrayBufferLike; }'.",
        "post": "TS2339: Property 'nosuchProperty' does not exist on type '{ comment: Uint8Array OF ArrayBufferLike; literal: Uint8Array OF ArrayBufferLike; interpolation: Uint8Array OF ArrayBufferLike; }'."
      },
      {
        "snippet": "const { alsoNotThere } = scanSource('const a = 1;'); export const x = alsoNotThere;",
        "pre": "TS2339: Property 'alsoNotThere' does not exist on type '{ comment: ...; literal: ...; }'.",
        "post": "TS2339: Property 'alsoNotThere' does not exist on type '{ comment: ...; literal: ...; interpolation: ...; }'."
      }
    ],
    "controls_clean_on_both_sides": [
      "scanSource(s).comment  -> pre (none), post (none)",
      "scanSource(s).literal  -> pre (none), post (none)"
    ],
    "why_the_second_leg_matters": "reading .interpolation clean is ALSO satisfied by a return type destroyed into any / an index signature, where every name reads clean. The absent-property leg staying TS2339 -- with its message now enumerating THREE real properties instead of two -- is what proves widening rather than destruction. Both legs ran in the same run on each side.",
    "fixture_hygiene": "no comment of any kind inside any probe or pin-test fixture, so no token with a ts- prefix can be parsed as a real directive"
  },
  "typedef_decision": {
    "decision": "NO named @typedef. Narrow fix only: interpolation added to the @returns object type, plus a short description of the three arrays.",
    "reasons": [
      "MEASUREMENT: a named typedef earns its keep when something needs to NAME the shape -- a variable annotation, a parameter type, a return type elsewhere, or a duplicated hand-written type to deduplicate. Measured on my base: ZERO of all four exist.",
      "ZERO of 32 direct call sites bind the whole result to a name; 18 destructure at the call site and 10 read one member at the site, where inference already supplies the type with no name needed.",
      "ZERO hand-written named types duplicate the shape (matcher over all 4947 tracked JS/TS-family files; NONSENSE CONTROL impossible name = 0; POSITIVE CONTROL same matcher shape on a name that certainly exists = 309 HITS).",
      "A typedef would add a SECOND declaration site with no reader -- the same class of drift (a declaration that can disagree with what it describes) that this very card exists to close.",
      "The triage comment on this card explicitly rules the typedef question out of scope and says it must not ride in. The measurement agrees with the triage rather than contradicting it, so no conflict had to be resolved against a ruling."
    ],
    "if_it_is_ever_wanted": "the trigger to revisit is a consumer that binds the whole result to a name or annotates the shape -- today that count is 0"
  },
  "scansource_body_unchanged": {
    "recipe": "sha256[:16] of lines DECLARATION..CLOSING_BRACE, no trailing newline (recipe reverse-engineered until it reproduced the card's hash exactly)",
    "pre": "8e715c3a20dc63fc  (lines 222-437 at base 7098eed365)",
    "post": "8e715c3a20dc63fc  (lines 226-441 after the docblock grew 4 lines)",
    "card_expected": "8e715c3a20dc63fc",
    "match": true,
    "non_empty_guard": "sha256 of the empty string is e3b0c44298fc1c14 and was printed alongside for comparison -- the body hash is not it, so nothing was hashed empty",
    "also_held_during_ablation": "8e715c3a20dc63fc -- the mutation touched only the docblock"
  },
  "call_sites": {
    "population": "every direct `scanSource(` occurrence in the CODE (comments stripped by the module's own stripComments, so prose is not scored as code) of all 4947 tracked JS/TS-family files, enumerated from the git index of a verified-clean worktree at base 7098eed365",
    "total_direct_call_sites": 32,
    "destructured_at_the_call_site": 18,
    "single_member_read_at_the_site": 10,
    "whole_result_bound_to_a_name": 0,
    "unclassified": 3,
    "unclassified_detail": "1 = the declaration itself in js-comment-mask.mjs; 2 = string literals (a corpus-gate error message, and a fixture string inside the 9324 pin test). stripComments strips comments, not string literals, hence these.",
    "files_whose_code_calls_scanSource": 14,
    "files_reading_interpolation": 2,
    "files_reading_interpolation_detail": "scripts/check-entry-guard.mjs (the one real external consumer) and scripts/js-comment-mask.mjs itself (selfTest)",
    "files_reading_comment_POSITIVE_CONTROL": 13,
    "files_reading_literal": 11,
    "nonsense_control": "scanSourceZZZ( in code = 0, as expected",
    "ts_files_in_the_program_reading_interpolation": 0,
    "ts_files_in_the_program_reading_comment_CONTROL": "5 -- HITS, so the matcher works on this input. The card reported 1 for the same control at fb4ec65daf; mine is a differently-scoped population (all .ts under scripts/, test files included) and is re-derived, not inherited."
  },
  "summary": "Premise confirmed on my own base, not inherited. scanSource's @returns declared two properties while the function returns three, and under allowJs+checkJs=false that docblock IS the type a .ts consumer gets. Added interpolation to the @returns object type plus a four-line description of what the three arrays are; the function body is byte-identical on both sides (8e715c3a20dc63fc). Added scripts/__tests__/js-comment-mask-returns-interpolation-9424.test.ts, which compiles real reads against the real .mjs under the real project options and asserts the DIAGNOSTIC rather than the tag's spelling -- pinning BOTH directions, so an edit that drops the tag AND an edit that loosens the shape into any both go red. Changeset added with empty frontmatter (deliberate no-release declaration, the same first-class form the sibling card used); the presence gate says none is owed, so it is a declaration, not a bump. Draft PR 9434 opened and deliberately left in draft for the PM.",
  "probe_block": [
    {
      "leg": "claim verification",
      "command": "mcp issue_read get_comments on 9424",
      "population": "all comments on 9424",
      "result": "newest Claim: is comment 5656195082 and it names claude/issue-9424-scansource-returns-interpolation. Inherited, no second claim posted, assignee never written.",
      "reader_used": "MCP issue_read, because the claim is comment state and git cannot see it"
    },
    {
      "leg": "body-hash recipe calibration",
      "command": "four hash variants of the declaration-through-closing-brace span",
      "population": "scripts/js-comment-mask.mjs at base 7098eed365",
      "pre": "withNL=8e32345567a07136, noNL=8e715c3a20dc63fc, no-export-keyword=8ce27a94957e2f29, doc+body=6cd4cb7bd23f6c90",
      "post": "n/a -- calibration leg",
      "control": "the card's stated hash 8e715c3a20dc63fc; exactly ONE variant reproduces it -> recipe identified as noNL, and the match also proves the body is unchanged since fb4ec65daf. NON-EMPTY GUARD: empty-string sha256 is e3b0c44298fc1c14, printed for contrast.",
      "control_hit": true,
      "reader_used": "printf '%s' with command substitution to strip the trailing newline; a plain sed | sha256sum pipe gives the withNL variant and would have silently failed to match"
    },
    {
      "leg": "subject is in the type-check program",
      "command": "pnpm exec tsc -p tsconfig.scripts.json --listFiles > file 2>&1; EXIT=$?  (redirect-then-capture)",
      "population": "the 936 files tsc itself puts in the tsconfig.scripts.json program",
      "pre": "EXIT=0; scripts/js-comment-mask.mjs present at line 571",
      "post": "pnpm type-check:scripts EXIT=0",
      "control": "NONSENSE js-comment-mask-NOSUCH.mjs = 0 (absent, as required). POSITIVE js-comment-mask-param-types-9324.test.ts = line 806, HITS.",
      "control_hit": true,
      "reader_used": "tsc's own --listFiles, because a grep of the include glob would answer a different question than what tsc actually loaded"
    },
    {
      "leg": "diagnostic flip",
      "command": "node flip-probe.mjs (ts.createProgram over an in-memory case file at a real path inside scripts/__tests__/), run once before the edit and once after",
      "population": "6 snippets: 2 widening subjects, 2 genuinely-absent controls, 2 genuinely-declared controls",
      "pre": "interpolation member TS2339 | interpolation destructured TS2339 | nosuchProperty TS2339 | alsoNotThere TS2339 | comment clean | literal clean",
      "post": "interpolation member CLEAN | interpolation destructured CLEAN | nosuchProperty TS2339 | alsoNotThere TS2339 | comment clean | literal clean",
      "control": "the two genuinely-absent properties -- they must STAY errors, and they did; their message went from naming two properties to naming three",
      "control_hit": true,
      "reader_used": "the compiler itself; a grep for the tag would assert a spelling, and a spelling is worth nothing unless TypeScript acts on it"
    },
    {
      "leg": "call-site census for the typedef judgement",
      "command": "node typedef-measure.mjs over git ls-files output, each file's comments stripped by the module's own stripComments",
      "population": "4947 tracked JS/TS-family files at base 7098eed365; worktree proven clean (git status --porcelain = 0 lines) so the index equals what was read from disk",
      "pre": "32 direct call sites: 18 destructured, 10 single-member, 0 whole-result-bound, 3 unclassified. 0 hand-written duplicate types.",
      "post": "unchanged by this PR (no call site edited)",
      "control": "NONSENSE scanSourceZZZ( = 0 and an impossible type name = 0, both as expected; POSITIVE CONTROL for the same type-name matcher on a name that certainly exists = 309 HITS, so the matcher is not structurally blind. ALL MATCHED LINES PRINTED for every bucket, including the empty one.",
      "control_hit": true,
      "reader_used": "the module's own stripComments, exactly as the filing card did, so prose is not scored as code -- a line-oriented grep would have counted the 2 prose-only files as consumers"
    },
    {
      "leg": "reverse verification (ablation)",
      "command": "bash ablate.sh -- fix committed FIRST, then the @returns reverted to its pre-fix two-property form, with trap '...checkout HEAD -- REL' EXIT INT TERM and an absolute REPO_ROOT resolved before mutating",
      "population": "scripts/js-comment-mask.mjs",
      "pre": "on-disk proof of the mutation, not the editor's exit code: pre-fix text count 0 -> 1, post-fix text count 1 -> 0, blob hash fefd9819... -> 561d2857...; HEAD blob hash captured first and checked non-empty (an empty hash would have been read as FAILURE, not as nothing-to-compare)",
      "post": "restore proven by STATE not by exit code: blob hash back to fefd9819..., git diff HEAD = 0 lines, post-fix text count back to 1; pin test green again 8/8",
      "control": "objectui#9324's pin test under the SAME mutation: 10/10 GREEN. Its subject is @param, not @returns -- so the red below is my tag being load-bearing, not allowJs or the harness failing wholesale.",
      "control_hit": true,
      "result": "new pin test 3 failed / 5 passed, and the split is exactly the predicted direction: red = interpolation member, interpolation destructured, and the message-enumerates-all-three case; green = comment, literal, both absent-property cases, and the in-program check. Predicted before running.",
      "reader_used": "git hash-object plus git diff HEAD for both legs, because a clean-exiting restore that did nothing is the failure mode that only state can detect"
    }
  ],
  "tests": {
    "pnpm type-check:scripts": { "pre": 0, "post": 0, "note": "PRE captured from the same compile invoked with --listFiles; POST from the named root script verbatim" },
    "pnpm exec eslint scripts/js-comment-mask.mjs scripts/__tests__/js-comment-mask-returns-interpolation-9424.test.ts": { "post": 0 },
    "pnpm exec vitest run scripts/": { "post": 0, "evidence": "Test Files 154 passed | 2 skipped (156);  Tests 4571 passed | 2 skipped (4573)" },
    "pnpm exec vitest run (new pin test + the 9324 control pin test)": { "post": 0, "evidence": "Test Files 2 passed (2);  Tests 18 passed (18)" },
    "node scripts/check-changeset-presence.mjs": { "post": 0, "evidence": "No source or published contract of a released package changed in this range, so no changeset is owed -- the empty-frontmatter changeset is a voluntary declaration" },
    "node scripts/check-changeset-no-major.mjs": { "post": 0 },
    "node scripts/check-changeset-fixed.mjs": { "post": 0 },
    "node scripts/check-governed-queue-guard.mjs --test (both changed paths)": { "post": 0, "evidence": "NOT GOVERNED -- 2 path(s) checked against 5 governed surface(s); none matched" },
    "capture_discipline": "every exit code captured by redirect-then-capture (cmd > file 2>&1; EXIT=$?), never read across a pipe",
    "not_run_locally": "pnpm test (full repo) and pnpm lint (repo-wide) -- left to CI; the diff is 3 files, all under scripts/ and .changeset/, and the whole scripts/ suite plus targeted eslint were run"
  },
  "acceptance_items_not_met": [],
  "open_questions": [
    {
      "question": "My dispatch said to MEASURE the @typedef question and decide with reasons; the triage comment on this card says the @typedef question is NOT in scope and must not ride in. Reporting the tension rather than picking a side silently.",
      "resolution_taken": "No conflict in the outcome: I measured, and the measurement independently says NO typedef (zero consumers need a name for the shape). So the narrow fix satisfies both instructions. Nothing rode in.",
      "for_PM": "no action needed unless you want the typedef revisited on different grounds than the measurement"
    },
    {
      "question": "My commit message carries a `Part of #9424` trailer. The seat convention is that card references live only in the PR body, not in commit messages, because squash concatenates them.",
      "resolution_taken": "`Part of` never closes anything, so it is harmless; and the no-force-push rule means I did not amend it away. Flagging it so it is on the record rather than discovered later. The single closing keyword is `Fixes #9424` on line 1 of the PR body, verified once by a pre-publish keyword scan and once by reading the published body back."
    }
  ],
  "out_of_scope_findings": [
    "REPORTED ONLY, not filed and not fixed, per dispatch. scripts/check-comment-mask-corpus.mjs documents a pluggable masker as a module exporting scanSource(source), and its usage example stubs one as returning ONLY { comment } -- no literal, no interpolation. That stub is narrower than the shape this card just pinned. It appears deliberate (compareFile only reads comment), so I am recording it as an observation rather than a defect; if the corpus gate ever grows a literal or interpolation reader, that documented stub becomes a trap.",
    "No other defects observed. Nothing was filed."
  ],
  "mcp_calls": "5 -- issue_read x2 (issue body, comments/claim), create_pull_request x1, pull_request_read x1 (body read-back), add_issue_comment x1 (this report). Everything else was git, tsc, node and vitest locally."
}

_{os-dev seat, dispatched by the domain:devx @ objectui PM seat · session session_01FhBNJcLRZLe8M87VcUgpKr · branch claude/issue-9424-scansource-returns-interpolation · PR objectui#9434 (draft, deliberately not flipped ready)}

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Generated by Claude Code

[claude]

✅ LANDED — PR objectui#9434 merged fb097b8479 at 2026-09-13T22:07:24Z. Full probe, re-confirmed against the actual <merge>^ = 7098eed365: objectui#9434 #issuecomment-5656296821 (pre-merge) and the LANDED note above it.

main now carries at :220 — @returns {{ comment: Uint8Array, literal: Uint8Array, interpolation: Uint8Array }} — plus a four-line description of what the third array flags. scanSource's body is byte-identical across the merge (8e715c3a20dc63fc), so the function this card's sibling used as its control is still exactly that.

The acceptance was a two-sided diagnostic flip, verified with the compiler: .interpolation goes error → clean, while a genuinely-absent property stays TS2339 with its message now enumerating three real properties. ⭐ The second leg is the one that carries the proof — reading .interpolation cleanly would equally be satisfied by a return type collapsed into any, and only the absent-property control distinguishes widened from destroyed. The landed pin test asserts that diagnostic rather than the tag's spelling, in both directions.

The @typedef question this card raised and deliberately did not settle: answered NO, by measurement. 32 direct call sites — 18 destructure at the site, 10 read one member, 0 bind the whole result to a name, and 0 hand-written types duplicate the shape (nonsense control 0; positive control 309 hits). A typedef needs something that must name the shape, and all four criteria measure zero, so it would add a second declaration site with no reader — the same drift class this card closes. A revisit trigger is recorded in the PR.

⭐ Filing this as its own card rather than riding it into objectui#9324 was the right call and is now visibly so: that card needed scanSource byte-identical to prove its own point, and the same hash appears in both PRs' probes two merges apart.

⚠️ Reported by the dev, ⛔ not filed, ⛔ not fixed: scripts/check-comment-mask-corpus.mjs documents a pluggable masker whose usage example stubs a scanSource returning only { comment } — narrower than the shape now pinned. Deliberate today (its compareFile reads only comment), but a trap if that gate ever grows a literal or interpolation reader.

Closing; pm:queue and the assignee are stripped. bug / priority:p3 / domain:devx left alone — ⛔ not this seat's to produce or change.

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Generated by Claude Code