[Karibhou]

📌 Fixes

Closes #569

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📝 Summary of Changes

• scripts/markdown-fences.ts now exports one FenceTracker class: a line-by-line classifier (outside / opener / inside / closer) holding the single fence rule. The rule: same marker character, closer at least as long as the opener, no info string on the closer, and the CommonMark exception for a backtick opener whose info string contains a backtick.
• findClose and convertBlocks in scripts/mdx-to-markdown.ts use the tracker. Their own FENCE_RE and the two hand-rolled opener/closer checks are gone.
• splitFencedSegments and normalizeFences use the same tracker. The private isFenceCloser/OpenFence helpers are gone, which means three separate fence trackers are now one.

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Changes Made

• Refactored the fence tracking in markdown-fences.ts and mdx-to-markdown.ts onto FenceTracker
• Added a test for the one behaviour change: mdx-to-markdown used to treat a line like ```not`a`fence as a fence opener, so a </Step> after it was hidden and reported as unterminated. It now follows the shared CommonMark rule. The test fails on main and passes here.
• Added changelog fragment changelog.d/fixed-569-mdx-shared-fence-rule.md

Not changed: withCodeProtected in mdx-to-markdown.ts. It masks fenced blocks and inline code with placeholders across the whole text before running the regex passes, which is a different job from line classification. Moving it to segment-based masking would change which text the import/export regexes can see, so it is out of scope for this style finding.

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Checklist

• I have reviewed the project's contribution guidelines.
• I have performed a self-review of my changes.
• I have written unit tests for the changes (if applicable).
• I have updated the documentation (if applicable).
• I have tested the changes locally and ensured they work as expected.
• All CI checks are passing.

Local runs: npx vitest run --coverage (121 files, 1404 tests passed, coverage gate met), npm run type-check, eslint and prettier --check on the changed files, and markdownlint-cli2 on the fragment.

Security Considerations

• Dockerfiles — verified base images, avoided running as root
• Kubernetes manifests — checked RBAC permissions and secrets handling
• CI/CD workflows — inspected for command injection or credential exposure
• Dependencies — validated new packages, checked for known vulnerabilities
• Security configs — changes align with project security policies

Not applicable: this PR changes only the sync scripts under scripts/.

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👀 Reviewer Notes

The refactor keeps splitFencedSegments and normalizeFences behaving exactly as before. Their existing tests pass unchanged.

— hive: backend=omp model=anthropic/claude-opus-5-5

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🐝 Hive Agent: contributor | SHA: a6c7250

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[hivecommons-hive]

Read FenceTracker and all four call sites at the PR head against main. This looks correct to me; the refactor is behaviour-preserving everywhere except the one change the body names.

• splitFencedSegments: old fenced was open !== null before the closer check, plus true on an opener — i.e. true for opener/inside/closer. fences.next(...) !== "outside" is the same set (scripts/markdown-fences.ts:67).
• normalizeFences: a backtick opener with a backtick in its info string used to short-circuit with out.push(line); it now classifies as outside and reaches the trailing out.push(line) (markdown-fences.ts:124) after the same \0AFTER_FENCE handling. Same output. The line.match(FENCE_RE)! on the opener branch is safe because the tracker only returns opener when the regex matched.
• findClose / convertBlocks (scripts/mdx-to-markdown.ts:177-180, 197-200): the dropped hand-rolled closer checks were character-for-character the tracker's rule (same marker char, >= length, empty info). The only delta is the CommonMark backtick-in-info exception, which the new test pins and which markdown-fences.test.ts:51 already asserted for the other scripts.

No findings.

— hive: agent=reviewer backend=copilot model=claude-fable-5.1 copilot=1.0.88

[hivecommons-hive]

Hive status — updated in place; edits do not notify. Full history is in the Activity Monitor.

Hive filed review findings that do not block this PR as backlog items:

• [reviewer] Review backlog (correctness): withCodeProtected still masks fences with its own regex, diverging from FenceTracker #571 — [reviewer] Review backlog (correctness): withCodeProtected still masks fences with its own regex, diverging from FenceTracker ([reviewer] Review backlog (correctness): withCodeProtected still masks fences with its own regex, diverging from FenceTracker #571)

Cap: 10 backlog item(s) per PR per day.

Review findings from reviewer-2 (folded here because this head already carries its hive review):

Read scripts/markdown-fences.ts and scripts/mdx-to-markdown.ts at a6c7250 against main; the refactor is behaviour-preserving for the two existing callers and the one intended change is pinned by a test. Looks correct to me.

• splitFencedSegments: the old fenced = open !== null / set-true-on-opener logic is exactly FenceTracker.next() !== "outside" (opener, inside and closer are all fenced). Same result.
• normalizeFences: the old backtick-with-backtick-info branch did out.push(line); continue after the \0AFTER_FENCE pop; the new code classifies it outside, runs the same pop, and reaches the trailing out.push(line). Same output.
• findClose / convertBlocks: previously tracked fences with their own FENCE_RE and no CommonMark backtick-in-info exception. Routing through the tracker adds that exception — the one behaviour change — and the new test in scripts/mdx-to-markdown.test.ts (notafence hiding </Step>) encodes it. The changelog fragment names the same thing.
• isFenceCloser/OpenFence were module-private; nothing else under scripts/ referenced them.

All checks green on this head. No findings.

Evidence bundle `#570a6c7250` sha256:d5cd4a2a74d31a541b3f1ac38c00777cce01bcd29d1e009b9427c33f4685d478 — download from the dashboard or `hivectl review evidence #570`.

[hivecommons-hive]

Merged by hive contributor-lane auto-merge: CI green for ≥10m, reviewer verdict approve, @Karibhou holds the trusted tier in this hive's contributor registry.