## Thinking Path
> - Paperclip is the open source app people use to manage AI agents for
work
> - The server has a task-drain admission hold so operators can stop new
agent work and wait for quiescence before maintenance
> - Cloud deploys restart tenant containers, but the Cloud control plane
has no sanctioned credential for the drain routes, so agent runs are
killed mid-restart
> - The only Cloud credential this server trusts is the runtime identity
assertion, deliberately scoped to the one-time bootstrap health call
> - This pull request adds a disjoint, action-bound Cloud control
assertion accepted only on the task-drain endpoint
> - The benefit is that Cloud can hold new work and drain a stack before
it restarts the container, through the same authorization and audit
paths a human operator uses
## Linked Issues or Issue Description
Refs #12485 (the task-drain admission hold this makes reachable for the
Cloud control plane).
**Problem or motivation**
Cloud deploys restart the container without stopping agent work first.
The task-drain hold from #12485 exists for exactly this, but its routes
require instance-admin board authority. The Cloud control plane holds no
such credential: the runtime identity assertion is accepted only on `GET
/api/health`, by design. So in-flight runs die at every deploy.
**Proposed solution**
A second, deliberately disjoint use of the same Cloud signing key
(`PAPERCLIP_CLOUD_RUNTIME_IDENTITY_JWKS`): a control assertion with its
own JWS type (`paperclip-cloud-control+jwt`), its own audience, an
`action` claim, a request id, and a short maximum lifetime. A new
middleware accepts the `x-paperclip-cloud-control` header only on
`/api/instance/task-drain`, binds each method to one exact action
(`task-drain:read` / `task-drain:start` / `task-drain:stop`), verifies
the assertion against the configured JWKS and
`PAPERCLIP_CLOUD_STACK_ID`, and installs a synthetic instance-admin
board actor so the existing route authorization, validation,
transactional audit, and activity publishing run unchanged (audit rows
record actor id `paperclip-cloud`). The header is rejected with 400
anywhere else, so it can never become an ambient credential. The board
mutation guard exempts the new `cloud_control` source exactly like the
other non-browser lanes.
**Alternatives considered**
Widening the existing runtime identity middleware would conflate a
one-time bootstrap claim with a repeatable management credential and
weaken both. A per-stack minted instance-admin API key would work with
no auth change but adds a long-lived privileged credential per tenant to
store and rotate. The action-bound short-lived assertion keeps
authorization per-call and stateless.
**Additional context**
Self-hosted instances have no `PAPERCLIP_CLOUD_STACK_ID` and reject
every assertion — the feature is inert off Cloud. A runtime identity
token cannot replay as a control token or vice versa (disjoint `typ` and
`aud`, covered by tests). The Cloud-side caller (drain before deploy,
bounded quiescence wait) lands separately in the Cloud control plane.
## What Changed
- `server/src/services/cloud-runtime-identity.ts`:
`verifyCloudControlAssertion` plus the control
header/audience/type/action constants, reusing the existing JWKS
resolution, JWS parsing, and lifetime discipline.
- `server/src/middleware/cloud-control.ts` (new): accepts the header
only on the task-drain endpoint, per-method action binding, installs the
synthetic instance-admin actor on success, 401 on invalid assertions,
400 anywhere else.
- `server/src/app.ts`: mounts the middleware directly after the actor
middleware, so a valid assertion replaces whatever actor the request
otherwise resolved to.
- `server/src/middleware/board-mutation-guard.ts`: `cloud_control` joins
the non-browser exemptions.
- `server/src/types/express.d.ts`,
`server/src/services/authorization.ts`: `"cloud_control"` added to the
actor source unions.
## Verification
- `pnpm exec vitest run --project @paperclipai/server
server/src/__tests__/cloud-control-task-drain.test.ts
server/src/__tests__/instance-settings-routes.test.ts
server/src/__tests__/heartbeat-task-drain.test.ts
server/src/__tests__/heartbeat-scheduling-suppression.test.ts
server/src/__tests__/cloud-runtime-identity.test.ts` — 87 tests, all
passing.
- `pnpm --filter @paperclipai/server exec tsc --noEmit` reports no new
errors against the base commit's known pre-existing set.
- The new suite covers: acceptance per method, cross-action rejection,
unknown-action rejection, runtime-identity-token replay rejection,
wrong-audience rejection, wrong-stack and self-hosted rejection, expiry
and oversized-lifetime rejection, unknown-key rejection, request id
validation, endpoint containment (400 elsewhere, 400 on unbound
methods), pass-through without the header, and the mutation-guard
exemption.
## Risks
Low risk, additive. No behavior changes without the header; the header
grants nothing outside the one endpoint; each assertion authorizes one
action for at most five minutes; the existing route-level validation,
queued transitions, and audit writes are unchanged. The browser-facing
Cloud proxy strips Cloud headers, and possession of the shared
tenant-session token cannot mint an assertion (signing key never leaves
Cloud).
## Model Used
Claude (Anthropic) — Fable 5 (`claude-fable-5`), extended thinking,
agentic tool use 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
(module doc comments carry the contract)
- [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
- [x] I will address all Greptile and reviewer comments before
requesting merge
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