test(streaming): kill piezoStream surviving mutants (#591 hit list)

[ng]

Summary

Works this week's top entry on the mutation hit list (#591): src/streaming/piezoStream.ts, 151 surviving mutants — the largest single contributor after last week's mqttBridge pass (#635).

• ~30 new tests + tightened assertions in existing ones, targeting the survivor list extracted from run 29145443368's mutation-report-streaming artifact:
  • readRawRecord: direct byte-level tests — every seq/data CBOR encoding width (inline/1/2/4/8-byte), the 23-byte inline boundary, per-byte key corruption, exact error messages, data: null for placeholders, exact nextOffset.
  • findIndexEntry: boundary-exact binary-search assertions (kills the </<= and loop-condition mutants).
  • decodeSensorFrames: primitive/null inner values must not abort the batch.
  • Seek: full-window replay is not silently truncated (64 MB cap regression), window boundary is inclusive at exactly +30s, replay stops for good at the first out-of-window frame, incomplete/droppedFrames absent on clean replays, distinct error messages for no-file vs no-frames, numeric-string and Infinity timestamps rejected.
  • Tail loop: split-record delivery is exactly-once with a seekable index offset (leftover-buffer offset accounting), resync warnings carry exact byte counts, resync from a malformed record that itself starts with 0xa2, Pod 3 scalar capSense snapshot, non-frzHealth frames don't reach server listeners.
  • Lifecycle: shutdown actually closes the listening port, connect/disconnect/drop-count log lines asserted (field-debugging surface per docs/DEBUGGING.md).
• One minimal source change: readRawRecord, findIndexEntry, int32BufferToArray, decodeSensorFrames added to the existing __test__ export so the parser can be tested without a WS server per assertion.
• New /mutation-hitlist skill (.claude/skills/mutation-hitlist/): packages the weekly workflow — issue lookup, artifact download, survivors.py extraction, killing-test playbook by mutator type, known equivalent-mutant categories, CI-based verification.

Expected remaining survivors are the documented equivalent classes: module-level initializer mutants (false survivors under the vitest runner's module cache), timing/perf-only values (poll intervals, yield cadence, read-chunk sizes), and double-guarded checks. The mutation-test label on this PR triggers the scoped CI run for exact numbers.

Test plan

• pnpm exec vitest run src/streaming/tests/piezoStream.test.ts — 91 passed, 0 failed
• eslint clean on both changed files
• mutation-test label applied → CI mutation run on this PR posts the before/after summary
• Compare PR mutation summary against the 151-survivor baseline; comment results on 📊 Mutation testing — weekly baseline #591

🛏️ Beam this PR onto a sleepypod ✨

Pick the snippet that matches your pod. Already-installed pods can't use the curl bootstraps below — sleepypod's egress firewall DROPs github.com, and the script that knows how to unblock WAN is the very file curl is trying to fetch. Use sp-update instead; it's on disk and opens WAN as its first step.

🔄 Already on a sleepypod (most common — review a PR on a running pod):

sudo sp-update test/piezostream-mutants-591

🚀 Fresh pod / first install — bootstraps from GitHub, rebuilds every push:

curl -fsSL https://raw.githubusercontent.com/sleepypod/core/test/piezostream-mutants-591/scripts/install \
  | sudo bash -s -- --branch test/piezostream-mutants-591

🎯 Pin to this exact build (run 29174117551 · 3081292) — fresh-pod path, locked to one CI artifact for reproducible review:

curl -fsSL https://raw.githubusercontent.com/sleepypod/core/3081292a8fc9bb6ae3c496199798d784208a39a2/scripts/install \
  | sudo bash -s -- \
      --branch test/piezostream-mutants-591 \
      --artifact-url 'https://nightly.link/sleepypod/core/actions/runs/29174117551/sleepypod-core.zip'

🧊 Artifact: sleepypod-core · self-destructs in 30 days 💥

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 5cdd9cac-68ac-4b64-bb43-3107bae02603

📥 Commits

Reviewing files that changed from the base of the PR and between 613b69a and 3081292.

📒 Files selected for processing (4)

• .claude/skills/mutation-hitlist/SKILL.md
• .claude/skills/mutation-hitlist/survivors.py
• src/streaming/piezoStream.ts
• src/streaming/tests/piezoStream.test.ts

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch test/piezostream-mutants-591

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

📢 Thoughts on this report? Let us know!

[github-actions]

🎉 This PR is included in version 2.5.0 🎉

The release is available on GitHub release

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[github-actions]

Mutation test report

Shard	Score	Killed	Survived	No cov	Timeout	Errors	Total
mutation-report-db	—	—	—	—	—	—	(report missing)
hardware-lib	68.2%	1667	592	180	7	985	3456
homekit	62.6%	290	164	9	0	201	689
hooks	73.5%	886	296	23	1	483	1707
server	59.5%	1421	595	371	2	1682	5117
services-scheduler	73.2%	561	186	16	3	251	1019
streaming	83.3%	1014	165	27	12	411	1638

Full HTML reports: mutation-report-<shard> artifacts. Actionable hit list: mutation-hitlist artifact.