review/content-lane: duplicates.ts's block-scalar detection lags source-evidence.ts's hardened version (comment-tolerance, digit order)

[phamngocquy]

Summary

src/review/content-lane/duplicates.ts has two call sites (parseSimpleFrontmatter at line ~77
and findDuplicateFrontmatterKeys at line ~132) that detect a YAML block-scalar header (|, >,
|-, |2-, etc.) using:

/^[|>][+-]?\d*$/.test(inline)

The sibling parser in src/review/content-lane/source-evidence.ts was previously hardened (in
#8016) into a shared, more correct check:

const BLOCK_SCALAR_INDICATOR = /^[|>](?:[+-]?\d?|\d[+-]?)$/;
function isBlockScalarHeader(raw: string): boolean {
  return BLOCK_SCALAR_INDICATOR.test(stripYamlComment(raw));
}

This hardened version (a) accepts the indentation digit before or after the chomping indicator
(|2- as well as |-2), and (b) strips a trailing inline comment first, so | # sources below
is still recognized as a block-scalar header. duplicates.ts's regex has neither fix.

Concretely, duplicates.ts fails to recognize: |2- (digit-then-chomp order), and any
block-scalar header with a trailing comment (| # note, |- # note, |2- # trailing). When that
happens, the header line collapses to the literal string "|" and the real indented block content
that follows is silently skipped by the parser loop (indented lines don't match the key: regex).

This directly undermines duplicates.ts's own stated purpose (per its file-level doc comment: "a
regex parser that silently drops block/folded/list values would let a contributor hide a
protected-field edit and bypass the protected-edit + duplicate gates"). A protected field written
as description: | # note followed by indented content would parse to "|" both before and after
an edit, so protectedFrontmatterChanges would never detect the real content change, and two
semantically-different entries using this style would collide as "same normalized description" in
the duplicate detector.

This is the same cross-file divergence class already fixed twice between these exact two files:
#7250 and #8016 (both closed) — this issue is the same class of gap, this time in the
opposite direction (source-evidence.ts is ahead, duplicates.ts lags).

Deliverables

• duplicates.ts's parseSimpleFrontmatter recognizes |2--style and comment-trailing
  block-scalar headers identically to source-evidence.ts.
• duplicates.ts's findDuplicateFrontmatterKeys recognizes the same headers identically.
• New test cases (in the existing duplicates.ts test file under test/unit/) covering: a
  |2- header, a |- # comment header, and a > # comment header, each asserting the
  indented block content that follows is correctly captured (for parseSimpleFrontmatter) or
  correctly skipped without producing a spurious duplicate/parse error (for
  findDuplicateFrontmatterKeys).

All three deliverables are required in this single PR.

Test plan

This repo enforces 99%+ Codecov patch coverage, branch-counted, on every changed line/branch in
src/**. The new test cases above must exercise both fixed call sites.

Fixes #9290

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.46%. Comparing base (ffdea0c) to head (40b0340).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9366      +/-   ##
==========================================
+ Coverage   75.38%   75.46%   +0.08%     
==========================================
  Files         275      276       +1     
  Lines       58023    58227     +204     
  Branches     6181     6263      +82     
==========================================
+ Hits        43739    43943     +204     
  Misses      14014    14014              
  Partials      270      270              

Flag	Coverage Δ
backend	100.00% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/review/content-lane/duplicates.ts	100.00% <100.00%> (ø)

[loopover-orb]

Tip

✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-27 15:23:24 UTC}

2 files · 1 AI reviewer · no blockers · readiness 98/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
This ports source-evidence.ts's hardened block-scalar detection into duplicates.ts's two call sites (parseSimpleFrontmatter and findDuplicateFrontmatterKeys), replacing the narrower `/^[|>][+-]?\d*$/` regex with a shared `isBlockScalarHeader`/`stripYamlComment` pair that accepts digit-before-or-after-chomp order and strips a trailing inline comment before matching. I traced the new `BLOCK_SCALAR_INDICATOR` regex against the added test cases (`|2-`, `|- # trailing note`, `> # folded note`) and it matches correctly, and the block-gather loop still uses the raw (unstripped) `inline` for the `>` vs `|` join-style check, which is fine since the comment suffix doesn't change the leading character. The change is narrowly scoped to the stated divergence, mirrors the sibling module's already-reviewed logic (#8016), and ships matching tests for both `parseSimpleFrontmatter` and `findDuplicateFrontmatterKeys` including the false-positive-avoidance case (indented pseudo-keys inside the comment-suffixed block body).

Nits — 4 non-blocking

• stripYamlComment (duplicates.ts:41) only strips a comment preceded by whitespace, so a header written as `|#comment` (no space) would still fail to normalize — same limitation likely exists in source-evidence.ts, so this is consistent, but worth a shared unit test if not already covered there.
• No explicit test for a bare digit-only header like `|2` (no chomping indicator) even though the regex's first alternation branch covers it; consider adding one for full branch clarity.
• Since this logic is now duplicated verbatim between duplicates.ts and source-evidence.ts, consider factoring `stripYamlComment`/`isBlockScalarHeader`/`BLOCK_SCALAR_INDICATOR` into a shared helper module so a third divergence (this is the third fix of this exact class per content-repo-spec's sourceUrlFields omits the snake_case aliases its sibling urlFields already has #7250/source-evidence.ts's parseSimpleFrontmatter silently drops a scalar source field written as a YAML block/flow sequence, unlike duplicates.ts's parser #8016) can't recur.
• Confirm the PR is linked to an eligible open issue (tests reference 'review/content-lane: duplicates.ts's block-scalar detection lags source-evidence.ts's hardened version (comment-tolerance, digit order) #9290' but the truncated description doesn't show an explicit issue link) before merging, per repo convention.

Decision drivers

• ✅ Code review — No blockers (1 reviewer)
• ✅ Gate result — Passing (No configured blocker found.)

Context & advisory signals — never blocks the verdict

Signal	Result	Evidence
Linked issue	✅ Linked	#9290
Related work	✅ No active overlap found	No same-issue or scoped active PR overlap found.
Change scope	✅ 20/20	Low review scope from cached public metadata (1 linked issue).
Validation posture	✅ 25/25	PR body includes validation/test evidence.
Contributor workload	✅ 10/10	Author activity: 13 registered-repo PR(s), 6 merged, 0 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	phamngocquy; Gittensor profile; 13 PR(s), 0 issue(s).
Improvement	✅ Minor	risk: clean · value: minor · LLM: moderate

Linked issue satisfaction

Addressed
The diff ports BLOCK_SCALAR_INDICATOR, isBlockScalarHeader, and stripYamlComment into duplicates.ts and applies isBlockScalarHeader at both call sites (parseSimpleFrontmatter and findDuplicateFrontmatterKeys), matching source-evidence.ts's logic exactly, and adds the required |2-, |- # comment, and > # comment test cases for both functions.

Review context

• Author: phamngocquy
• Role context: outside_contributor
• Public audience mode: oss maintainer
• Lane context: Repository is configured for direct PR review.
• Public profile languages: Java, Python, Lua, Jupyter Notebook, C, Dockerfile, JavaScript, Shell
• Official Gittensor activity: 13 PR(s), 0 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Keep the PR focused and include validation evidence before maintainer review.

Signal definitions

• Related work = same linked issue, overlapping active PRs, or title/path similarity.
• Change scope = cached public metadata such as size labels, draft state, and review-burden hints.
• Validation posture = whether the PR provides enough public validation/test evidence for maintainer review.
• Contributor workload = public contributor activity and cleanup pressure, not a repo-wide quality failure.
• Contributor context = public GitHub/Gittensor identity context; non-Gittensor status is not a blocker.

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_{🟩 Safe / merged · 🟦 Advisory · 🟨 Held for review · 🟥 Blocked / closed}

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LoopOver approves — the gate is satisfied and CI is green.