## Thinking Path
> - Paperclip is the open source app people use to manage AI agents for
work
> - Its PR CI runs the general-server vitest lane pinned to
`maxWorkers=1` and sharded across 3 runners (introduced in #8360)
> - Suites were assigned to shards round-robin by sorted file index, so
shard test time was unbalanced: a recent PR run split 73s / 153s / 115s,
and the heaviest shard made "General tests (server 2/3)" the slowest
check in the whole workflow at 314s wall
> - The slowest shard sets the lane's wall time, so unbalanced
partitions waste the other two runners and stretch the PR critical path
> - This pull request replaces the round-robin assignment with a
deterministic longest-processing-time partition weighted by a checked-in
per-suite duration manifest
> - The benefit is near-even shard weights (projected 113s / 113s / 113s
with the current manifest), taking roughly 40s off the PR critical path
with no reduction in coverage
## Linked Issues or Issue Description
- Refs #8360 (introduced the 3-way general-server sharding this PR
rebalances)
- No public issue exists. Problem: the general-server test lane's
round-robin shard assignment ignores per-suite duration, so one shard
can carry multiple 30s+ suites while another finishes in half the time;
the slowest shard alone determines the check's wall time.
## What Changed
- `scripts/general-server-shard.mjs` (new): manifest loader and
deterministic LPT (longest-processing-time) partitioner; suites missing
from the manifest get the median recorded weight, and a missing or
malformed manifest degrades to uniform weights so the lane never fails
on stale data
- `scripts/general-server-shard-durations.json` (new): per-suite
duration manifest sampled from a real PR run (240 suites); the
`$comment` field documents how to regenerate it
- `scripts/run-vitest-stable.mjs`: both shard-selection sites (run and
`--dry-run`) now use the balanced partition instead of index round-robin
- `scripts/__tests__/run-vitest-stable-shard.test.mjs`: 6 new tests
covering skew-balance vs round-robin, determinism, median fallback for
unlisted suites, malformed-manifest degradation, manifest coverage of
the current suite set, and real-partition balance
- `server/src/__tests__/heartbeat-issue-rewake-throttle.test.ts`:
hardened the `afterEach` sweep — post-run bookkeeping (run-event
records, follow-up wake scheduling) can still insert rows briefly after
a run reaches a terminal status, and a late insert landing between the
`agent_wakeup_requests` and `agents` deletes failed teardown with a
foreign-key violation on the first CI attempt of this PR; the sweep now
retries so a late background write cannot take down the shard
- `release-verify.yml` shares the same runner script and inherits the
balancing with no workflow change
## Verification
- `node --test scripts/__tests__/run-vitest-stable-shard.test.mjs` — 9/9
pass (run against current master)
- `npx vitest run src/__tests__/heartbeat-issue-rewake-throttle.test.ts`
— 6/6 pass against embedded Postgres with the hardened teardown
- `node --test scripts/__tests__/release-verify-workflow.test.mjs` — 2/2
pass
- `node scripts/run-vitest-stable.mjs --dry-run` with each shard flag
shows every suite assigned exactly once across the 3 shards, with
projected weights ~113s each
## Risks
- Low risk: partition changes which runner executes which suite, not
what runs; a completeness test asserts every suite is assigned to
exactly one shard
- The duration manifest will drift as suites are added/changed; unlisted
suites get the median weight and a coverage test flags when the manifest
covers less than half the suite set, so drift degrades balance
gracefully rather than breaking the lane
> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.
## Model Used
- Claude Fable 5 (`claude-fable-5`, Anthropic), extended thinking
enabled, agentic tool use (file edits, shell, test execution) via Claude
Code
## Checklist
- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have searched GitHub for duplicate or related PRs and linked
them above
- [x] I have either (a) linked existing issues with `Fixes: #` / `Closes
#` / `Refs #` OR (b) described the issue in-PR following the relevant
issue template
- [x] I have not referenced internal/instance-local Paperclip issues or
links (only public GitHub `#NNN` / `github.com/paperclipai/paperclip`
URLs)
- [x] My branch name describes the change (e.g. `docs/...`, `fix/...`)
and contains no internal Paperclip ticket id or instance-derived details
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] All Paperclip CI gates are green
- [x] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge
---------
Co-authored-by: Claude (Paperclip SWE) <noreply@paperclip.ing>
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