test(web): lock in transcript search null/empty behavior (#908)

[groupthinking]

Summary

Closes the single open gap on #908 by adding the regression coverage its
acceptance criteria claim, without touching the optimization itself.

This is not a competing implementation. #908 explicitly forbids one. The
perf work already landed on main via merged PR #972 (ded0eccf3) and is
correct — I verified both call sites hoist properly. Behavior here is
byte-for-byte preserved; the logic is only relocated so it can be tested.

The finding

#908 lists this as satisfied:

• Null and empty search behavior is preserved.

It is preserved — but nothing enforced it:

Component	Tests before	Ships in production
InteractiveTranscript.tsx	0	yes, via dashboard/panels.tsx
TranscriptViewer.tsx	0	yes, via dashboard/panels.tsx

The refactor added the null guards (seg.text ? … : false, part ? … : '')
precisely because nullish text was a live risk — so they were load-bearing from
day one. A future refactor could drop them and every check would stay green.

Approach, and the constraint

apps/web/vitest.config.ts sets environment: 'node' deliberately:

Uses the node environment because the current suite exercises pure logic …
Add a jsdom project later if/when component rendering tests land.

Introducing jsdom/RTL would be an architectural decision that isn't mine to make
unilaterally, and rendering tests aren't needed to lock in this invariant.

So: extract the pure predicate into src/lib/transcript-search.ts and test it in
the node env. Precedent already exists — src/lib/timestamp.ts is shared pure
logic imported by these exact two components.

Rejected alternative: replicating the predicate inside the test. That
validates a copy rather than the shipped code — a vacuous test.

InteractiveTranscript re-exports TranscriptSegment, so panels.tsx needed no
changes.

Covered invariants (16 tests)

• empty / null / undefined query returns all segments, never zero
• nullish seg.text is a non-match, never a thrown TypeError
• case-insensitive matching in both directions
• speaker + search compose as AND, not OR
• regex metacharacters escaped — "a.b" must not match "axb"
• invalid raw patterns ((, [) do not throw
• highlight regex omits /g so .test() cannot desync via lastIndex
• the query is lowercased exactly once per pass, not once per segment

That last one asserts the actual performance property #972 shipped. A regression
to per-segment normalization now fails the suite instead of silently costing N
allocations per keystroke.

Non-vacuous by negative control

Each guard reverted individually in the shipped module, not in the test:

#	Mutation	Result
NC-1	drop seg.text ? guard	1 failed / 15 passed
NC-2	drop empty-query guard	2 failed / 14 passed
NC-3	drop regex escaping	2 failed / 14 passed
NC-4	add /g flag	1 failed / 15 passed
NC-5	normalize inside the loop	1 failed / 15 passed
NC-6	drop null short-circuit	1 failed / 15 passed
—	restore	16 passed

Every mutation is caught. No test passes for the wrong reason.

Verification

A/B against a stashed baseline (ambient AI_GATEWAY_API_KEY unset for hermeticity):

	Files	Tests	Failed
baseline (stashed)	44	245	0
with changes	45	261	0

Zero new failures. tsc --noEmit clean, eslint clean.

Refs #908, #972

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
v0-uvai	Ready	Preview, v0	Aug 2, 2026 2:56pm

[coderabbitai]

Important

Review skipped

Auto reviews are limited based on label configuration.

🏷️ Required labels (at least one) (1)

• [‘architecture-gap’, ‘bug’, ‘ci-cd’, ‘ci/cd’, ‘copilot-rabbit’, ‘documentation’, ‘duplicate’, ‘enhancement’, ‘frontend’, ‘github_actions’, ‘good first issue’, ‘help wanted’, ‘high-priority’, ‘invalid’, ‘javascript’, ‘ml-model’, ‘needs-triage’, ‘pipeline-critical’, ‘placeholder-code’, ‘priority:high’, ‘python’, ‘python:uv’, ‘question’, ‘styling’, ‘tests’, ‘v0’]

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository YAML (base), Repository UI (inherited), Organization UI (inherited)

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: a9dc76ba-77e4-4dad-b5c9-db673b82ab62

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Snapshot Warnings

⚠️: No snapshots were found for the head SHA 82459d4.

Ensure that dependencies are being submitted on PR branches and consider enabling retry-on-snapshot-warnings. See the documentation for more information and troubleshooting advice.

Scanned Files

None

[github-actions]

Agent Completion Truth Gate: NOT_APPLICABLE

Evidence agrees.

Machine-readable verdict

{
  "details": {},
  "reasons": [],
  "verdict": "not_applicable"
}

Workflow evidence

[linear-code]

GRV-376