The build-llms regen-drift guard caught that llms-full.txt was stale relative
to the CHANGELOG + CLAUDE.md edits in the prior commit. Per CLAUDE.md the
bundle is auto-derived: bump VERSION/CHANGELOG/CLAUDE.md, then run
`bun run build:llms`. Did the second part now.

llms.txt unchanged (it's just the curated index). Only llms-full.txt picks
up the v0.31.4.1 CHANGELOG entry and the new "Version format is mandatory"
section in CLAUDE.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Root cause of test (2) failing on the v0.31.4.1 PR (and on master since
#795 landed): CI's scripts/test-shard.sh hashed every test file into 4
shards via FNV-1a, INCLUDING *.serial.test.ts files. Serial files share
file-wide state (top-level mock.module, module singletons) that's
supposed to be quarantined by the .serial.test.ts naming + local
run-serial-tests.sh running them at --max-concurrency=1.

In CI the quarantine didn't apply. eval-takes-quality-runner.serial.test.ts
(new in #795) hashes into shard 2, where it calls:

  mock.module('../src/core/ai/gateway.ts', () => ({
    chat: async (opts) => { ... },
    configureGateway: () => undefined,
  }));

That replaces every export of gateway.ts at module-load time for the
WHOLE shard process. voyage-multimodal.test.ts also lives in shard 2
(both files happen to hash there), and it imports `embedMultimodal` from
gateway.ts. After the serial file loads, `embedMultimodal` is undefined
inside the shard process, and all 18 of voyage-multimodal's
embedMultimodal tests fail. Tests still passed locally because
run-unit-shard.sh excludes .serial files from its parallel pass.

Fix:
  - scripts/test-shard.sh: add `-not -name '*.serial.test.ts'` to the
    find expression so serial files no longer compete for shard buckets.
    Add --dry-run-list flag to mirror run-unit-shard.sh's interface so
    the regression test can introspect without spawning bun test.
  - .github/workflows/test.yml: add a `bun run test:serial` step that
    runs on shard 1 (which already runs `bun run verify`). Uses the
    existing scripts/run-serial-tests.sh which invokes bun test at
    --max-concurrency=1, matching local behavior.
  - test/scripts/test-shard.slow.test.ts: 4 regression cases that pin
    the contract (no serial files in any shard, no e2e files in any
    shard, plain files partitioned without overlap). .slow.test.ts
    because it shells out 4× with pure-bash FNV-1a hashing (~14s
    wallclock); excluded from the local fast loop, runs in CI via the
    same hash bucketing as other slow tests.
  - CLAUDE.md: update the CI vs local divergence section so this
    intentional asymmetry is documented going forward.

Build-llms drift in test (1) was fixed in the prior commit (c99a4af).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

The prior commit updated the "CI vs local: intentionally divergent file sets"
section in CLAUDE.md, which drifted llms-full.txt. Per CLAUDE.md the bundle
is auto-derived: edit CLAUDE.md, then run `bun run build:llms`. Did the
second part now.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>