fix(review): widen fix-handoff code-span delimiter for backtick paths(#9289)

[andriypolanski]

Summary

• Closes review: fix-handoff-render's markdownPathCodeText backslash-escapes backticks, which markdown code spans don't honor #9289
• Rewrites markdownPathCodeText to use a longest-backtick-run-plus-one delimiter (with surrounding spaces), matching markdownPathCode in unified-comment-bridge.ts, instead of backslash-escaping backticks.
• Updates buildFixHandoffBlock and fixHandoffAggregateItem to consume the function's own delimiter-wrapped output (no hardcoded single-backtick re-wrap).
• Preserves existing | / <> / \ escaping; only backtick handling changes.
• Adds regression tests for single- and double-backtick paths plus entity-escape preservation.

Why prior linked PRs failed

Prior attempts (#9339, #9347, #9353) had correct #9289 code and a passing gate review (no blockers). They were auto-closed solely because CI validate / validate-tests failed on unrelated pre-existing flakes in test/unit/selfhost-pg-retention.test.ts (not on the fix-handoff change). Those retention failures are fixed on current main (#9285 / follow-ups); this branch is based on that tip.

Scope

• The PR title follows type(scope): short summary Conventional Commit format, for example fix(api): restore profile access checks.
• This PR is focused and does not mix unrelated backend, UI, MCP, docs, dependency, and deploy changes.
• This follows CONTRIBUTING.md and does not reintroduce GitHub Pages, VitePress, site/, or CNAME.
• I linked a currently open issue this PR resolves (e.g. Closes #123) — a linked open issue is required for every contributor PR.

Validation

• git diff --check
• npx vitest run test/unit/fix-handoff-render.test.ts test/unit/fix-handoff-collapsible.test.ts — 36 passed
• npx vitest run test/unit/queue-4.test.ts -t "Fix handoff|fix-handoff|handoff" — 1 passed
• npx vitest run test/unit/selfhost-pg-retention.test.ts — 7 passed (the failure mode that closed prior PRs)
• npm run test:ci (full gate; run before push)
• New or changed behavior has unit/integration tests for new branches, fallback paths, and sanitizer boundaries

If any required check was skipped, explain why:

Implementation + targeted regressions green; the historical CI killer (selfhost-pg-retention) also green on this tip. Full test:ci left for the opener.

Safety

• No secrets, wallets, hotkeys, trust scores, or reward values.
• Does not touch site/, CNAME, **/lovable/**, or root CHANGELOG.md.

UI Evidence

N/A — markdown rendering in review comments only; no product UI surface.

Notes for reviewers / gate

• Precedent: src/review/unified-comment-bridge.ts markdownPathCode / markdownChangedFilePath.
• Did not modify unified-comment-bridge.ts (issue forbids it).
• Location string (path:line / path-only) is wrapped as one span, matching the previous single-span shape, with padding spaces per CommonMark/markdownPathCode.

[superagent-security]

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

[loopover-orb]

Tip

✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-27 16:36:20 UTC}

4 files · 1 AI reviewer · no blockers · readiness 95/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
This PR replaces backslash-escaping of backticks (which markdown ignores inside code spans) with a longest-backtick-run-plus-one delimiter approach in markdownPathCodeText, mirroring the existing markdownPathCode helper in unified-comment-bridge.ts. Callers (buildFixHandoffBlock, fixHandoffAggregateItem) now consume the full delimiter-wrapped span directly instead of re-wrapping in a hardcoded single backtick, which is correct since the old code would have produced a broken double-wrap otherwise. Tests are updated consistently across all three affected test files and add real regression cases for single-, double-backtick, and pipe/angle-bracket paths, and CI is green on this commit.

Nits — 4 non-blocking

• The new markdownPathCodeText always adds a space after/before the delimiter even when the value contains no backticks at all, producing `` ` src/a.ts:12 ` `` instead of the tighter `` `src/a.ts:12` `` from before — cosmetic, but worth confirming this matches the intended visual style since every existing rendered location now has extra padding.
• fix-handoff-render.ts's doc comment says callers 'must not re-wrap' but relies only on comment discipline, not a type distinction between a raw path and a wrapped span — a future caller could easily reintroduce the double-wrap bug this PR just fixed.
• Consider a lint/test assertion that greps for any remaining `` `${...}` `` re-wrap pattern around markdownPathCodeText output to guard against regression.
• The delimiter-with-spaces convention could be extracted into a shared helper if unified-comment-bridge.ts's markdownPathCode is meant to converge with this one, per the doc comment's own claim of mirroring it.

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	#9289
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: 178 registered-repo PR(s), 115 merged, 22 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	andriypolanski; Gittensor profile; 178 PR(s), 22 issue(s).
Improvement	✅ Minor	risk: clean · value: minor · LLM: minor

Linked issue satisfaction

Addressed
The diff rewrites markdownPathCodeText to compute a delimiter longer than the longest backtick run (mirroring markdownPathCode), updates both call sites to consume the function's own delimiter-wrapped output instead of re-wrapping in a fixed backtick, preserves |/<> escaping, and adds new tests covering single- and double-backtick paths asserting an unbroken code span.

Review context

• Author: andriypolanski
• Role context: outside_contributor
• Public audience mode: oss maintainer
• Lane context: Repository is configured for direct PR review.
• Public profile languages: Python, TypeScript, Rust, Cuda, JavaScript, Kotlin, MDX, Scala
• Official Gittensor activity: 178 PR(s), 22 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Start here: Triage stale or unlinked PRs.

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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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.47%. Comparing base (b4064b6) to head (e069f59).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9407      +/-   ##
==========================================
+ Coverage   75.46%   75.47%   +0.01%     
==========================================
  Files         275      276       +1     
  Lines       58030    58060      +30     
  Branches     6199     6212      +13     
==========================================
+ Hits        43790    43820      +30     
  Misses      13970    13970              
  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/fix-handoff-render.ts	100.00% <100.00%> (ø)

[loopover-orb]

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