## Thinking Path
> - Paperclip is the open source app people use to manage AI agents for
work.
> - Apps give those agents governed access to external tools.
> - Remote MCP setup needs secure endpoint validation and durable
credentials.
> - PostHog needs both browser sign-in and personal API key setup paths.
> - This pull request adds the shared remote MCP foundation and the
PostHog definition.
> - The benefit is a secure and reusable base for later app connection
work.
## Linked Issues or Issue Description
Refs #11965
This is stack 1 of 11. It replaces the first reviewable part of #11965.
## What Changed
- Add guarded remote MCP setup and credential handling.
- Add PostHog OAuth and API key connection methods.
- Add focused server, shared contract, and UI coverage.
- Keep the migration replay-safe and idempotent.
- Give the late-close security regression the same 10-second CI headroom
as the adjacent real-timer handshake test.
- Synchronize fake-timer handshake tests at the exact ensure-session
boundary so real filesystem setup cannot race the fake deadline.
- Drive PTY overflow coverage only after listener registration so
scheduling cannot reorder the test fixture.
## Verification
- pnpm exec vitest run
packages/adapter-utils/src/acpx-engine/execute.test.ts
server/src/__tests__/plugin-worker-manager.test.ts (220 passed; affected
cases also passed five focused stress repetitions)
- `pnpm exec vitest run
packages/adapter-utils/src/acpx-engine/execute.test.ts -t "never leaks a
sandbox-provided value from a late close rejection into logs or the
result"` (1 passed)
- `pnpm exec vitest run
packages/adapter-utils/src/acpx-engine/execute.test.ts -t "never
promotes a late ensureSession resolution|closes a late-resolving real
handle exactly once"` (2 passed)
- `pnpm -r typecheck`
- `pnpm --filter @paperclipai/server exec vitest run
src/__tests__/tool-access-service.test.ts`
- `pnpm --filter @paperclipai/db check:migrations`
- `pnpm build`
## Risks
- Remote endpoint validation can reject configurations that previously
passed without checks.
- OAuth configuration errors can block setup until the operator corrects
the provider settings.
- The migration uses guarded statements so repeated execution is safe.
- The test-only synchronization changes do not affect runtime behavior;
they remove filesystem/fake-clock and listener-registration races
observed under parallel CI load.
> I checked `ROADMAP.md`. This stack continues the existing app
connection work from #11965 and does not duplicate another planned item.
## Model Used
OpenAI Codex, GPT-5. The runtime model ID and context window were not
exposed. The model used reasoning, tool use, and code execution.
## 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 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: Paperclip <noreply@paperclip.ing>
Dotta