## Thinking Path
> - Paperclip is the open source app people use to manage AI agents for
work.
> - The `server/services/environments.ts` module lazily provisions a
managed Kubernetes sandbox environment for each company on first
heartbeat. Idempotency relies on `ensureKubernetesEnvironment` returning
the single managed row per company.
> - The `(company_id, driver)` unique index in the `environments` schema
is partial on `driver='local'` only, so two concurrent callers (e.g.
simultaneous first heartbeats from a freshly synced tenant) can both
insert a `driver='sandbox'` row before either sees the other.
> - The function tried to converge after the race by re-reading, picking
the oldest managed row as winner, and deleting the loser. Under
autocommit + read-committed, each post-insert SELECT is a fresh snapshot
— A may not see B's row, B may not see A's, so both pick their own and
neither deletes. Two rows survive.
> - The same race fired in CI as `expected 2 to be 1` at
`environment-service.test.ts:293`, gating multiple unrelated PRs on
retries.
> - This pull request encodes the operator-level invariant ("at most one
Paperclip-managed sandbox row per company") at the DB layer with a
partial unique index, then switches `ensureKubernetesEnvironment` to
`INSERT … ON CONFLICT DO NOTHING` keyed on that index. Losers re-read
the surviving row.
> - The benefit is the race is impossible by construction — no
application-side convergence loop, no test flake, and any future
`ensureXyzSandboxEnvironment` that sets `managedByPaperclip=true`
inherits the invariant for free.
## Linked Issues or Issue Description
Paperclip issue: PAPA-783 — implement managed-sandbox dedup fix (phase 2
of the approved plan on the parent flake-investigation issue).
This is the phase-2 fix for the flaky `environmentService > deduplicates
concurrent managed Kubernetes environment creation` test introduced by
`4ad94d0bd` (PR #7938). Failing CI runs since then on at least PRs
#7595, #8233, #8215, #8212. The plan was reviewed and approved on the
parent issue before implementation.
Closely related (not duplicates):
- PR #7938 — introduced the test and the in-process convergence loop
being replaced here.
- PR #7595, PR #8233, PR #8215, PR #8212 — downstream PRs affected by
the flake; one of them will be rebased onto this fix as the acceptance
gate.
## What Changed
- `packages/db/src/schema/environments.ts`: added
`environments_company_managed_sandbox_idx`, a partial unique index on
`(company_id) WHERE driver='sandbox' AND
(metadata->>'managedByPaperclip')::boolean = true`. The umbrella
`managedByPaperclip` predicate covers any current or future
Paperclip-managed sandbox flavor without needing a new index per
provider.
- `packages/db/src/migrations/0102_managed_sandbox_dedup_index.sql`:
one-shot dedup `DELETE` keeping the oldest managed-sandbox row per
`company_id` (scoped to `driver='sandbox' AND managedByPaperclip=true`),
`RAISE NOTICE` if any duplicates were removed, then `CREATE UNIQUE INDEX
IF NOT EXISTS environments_company_managed_sandbox_idx`. `CONCURRENTLY`
is omitted because the codebase's migration runner wraps each file in a
transaction (see `applyPendingMigrationsManually`); the table holds 1–3
rows per company, so the short lock is acceptable and consistent with
every other migration in the repo.
- `server/src/services/environments.ts`: `ensureKubernetesEnvironment`
now uses `INSERT … ON CONFLICT DO NOTHING` keyed on the new index. On
conflict it re-reads the surviving managed-sandbox row and returns it.
Drops the post-insert convergence (re-read by `createdAt ASC, id ASC`,
delete the loser) and the trailing comment that flagged "until a partial
unique index is added via migration" as the proper long-term fix.
- Unused `asc` import removed from
`server/src/services/environments.ts`.
## Verification
Local (matches the success criteria in the issue body):
```
$ cd server
$ passes=0; for i in $(seq 1 20); do
pnpm vitest run src/__tests__/environment-service.test.ts -t "deduplicates concurrent" \
&& passes=$((passes+1)) || break
done; echo "$passes/20"
20/20
$ passes=0; for i in $(seq 1 10); do
pnpm vitest run src/__tests__/environment-service.test.ts \
&& passes=$((passes+1)) || break
done; echo "$passes/10"
10/10
```
Adversarial fan-out stress (temporarily bumped `Array.from({ length: 8
}, …)` to `length: 32` on both dedup tests; reverted before commit):
```
$ # both dedup tests fan-out-of-32, 10 iterations
10/10
```
Two ensure paths exist in the parent plan, but only
`ensureKubernetesEnvironment` is on `master`.
`ensureManagedSandboxEnvironment` (referenced by the approved plan as
commit `dce9a9622`) lives only on an unmerged feature branch, not
master. The plan's helper-extraction and symmetric dedup test for that
path are deferred to whichever PR lands the second ensure path — it
inherits the same DB invariant by setting `managedByPaperclip=true`.
Discrepancy was flagged on the issue thread before implementation.
Typecheck:
```
$ pnpm -C server typecheck
ok
```
## Risks
Low risk.
- **Migration safety.** `IF NOT EXISTS` on the index makes the migration
idempotent. The dedup `DELETE` is bounded to rows matching the
managed-sandbox predicate; in production this should be a no-op (no race
has been reported in the wild — only in CI). On dev/CI DBs that already
accumulated duplicates, the migration emits a `NOTICE` reporting the
count.
- **No `CONCURRENTLY`.** The migration runner wraps each `.sql` file in
a transaction, which is incompatible with `CREATE INDEX CONCURRENTLY`.
The `environments` table holds 1–3 rows per company and the row count is
bounded by company count; the short ACCESS EXCLUSIVE during `CREATE
UNIQUE INDEX` is acceptable here and matches every other index migration
in the repo.
- **Predicate scope.** The partial index predicate matches exactly the
rows that `ensureKubernetesEnvironment` writes (`driver='sandbox'` with
`metadata.managedByPaperclip=true`). Tenant-created sandbox envs (via
`svc.create`) do not set this marker and are not covered — no false
positives, no surprise constraint violations on unrelated inserts.
## Model Used
Claude (Anthropic), `claude-opus-4-7`. Tool use: code edit + bash +
filesystem search; no extended-thinking mode.
## 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 run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [ ] All Paperclip CI gates are green
- [ ] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [ ] I will address all Greptile and reviewer comments before
requesting merge
Co-authored-by: Paperclip <noreply@paperclip.ing>
Devin Foley
f3e01c63bd