## Thinking Path
> - Paperclip is the open source app people use to manage AI agents for
work
> - The Rust runner now owns validated, scoped ACPX reducer events and
safe session suspension
> - Durable PRP transport must receive provider-neutral events rather
than sidecar-native envelopes
> - Semantic calls and questions must retain the exact run, session,
turn, item, and provider-request authority used by the durable command
stream
> - Terminal, result, assistant, process, and diagnostic events also
need one reviewed projection boundary
> - Permission requests remain impossible under the pinned Codex policy
and must fail closed if they reach projection
> - This pull request adds only that package-local projection without
selecting ACPX in runnerd
## Linked Issues or Issue Description
Refs #12422
## What Changed
- Add a validated durable ACPX event projection context bound to one
run, normalized session, turn, and item.
- Pass already normalized activity events through without reintroducing
provider-native envelopes.
- Project authorized tool calls into canonical semantic input receipts
with exact correlation and content digests.
- Project structured questions into provider-neutral
`paperclip.runtime_request.v2` events.
- Preserve both the public projected request identity and the original
provider request identity so responses resolve the exact sidecar
request.
- Project dynamic semantic operation results as `semantic_tool.result`;
only reserved finish/block operations may propose the run result.
- Project semantic completion results into `run.result.proposed`.
- Project terminal-flushed assistant messages on the final channel and
turn terminal states into existing provider-neutral event families.
- Project sanitized process metadata and diagnostics into bounded
harness diagnostics.
- Validate runtime-request origins against their strict durable shape
and fall back from empty optional titles to a valid question prompt.
- Reject invalid identities, projected-identity collisions, unstable
semantic receipt identities, permission requests, and cross-turn
projection fail closed.
- Add integration coverage across reducer event families, correlation,
identity validation, projected question resolution, and pinned-policy
denial.
- Document the durable projection boundary.
- Do not change dependencies, lockfiles, workflows, runnerd selection,
server behavior, UI, or migrations.
## Verification
- Replay base: `80639f4f69c8938eb74bdc0833df93e0ed91dab3` (`master`
after #12422 merged).
- Exact replay head: `3cb29581d2bcbc4b47f8069baffd721c6ce4e444`.
- Stable patch ID: `92910b56575e67ae83960177d467a565019ba282`.
- The exact delta is 22 files, 1,206 additions, and 59 deletions, all in
`packages/paperclip-runner`; it contains no lockfile, workflow, server,
UI, dependency, or migration change.
- `git diff --check` and the Cargo formatting check pass on the replayed
delta.
- Exact-head GitHub Actions run `33372209037` (attempt 2): **PASSED**
with 23/23 jobs passed.
- Greptile reviewed exact head
`3cb29581d2bcbc4b47f8069baffd721c6ce4e444`: **5/5**, with zero
unresolved review threads.
- Superagent, contributor trust, Socket, and Snyk security checks:
**PASSED**.
- No local test result is claimed. GitHub Actions is the authoritative
verification environment for this replayed revision.
## Risks
- This function accepts reducer output, not raw sidecar frames. Callers
must preserve the existing scope-first decode and reduction order.
- Semantic input includes the already sanitized provider input while its
content receipt uses the same canonical digest.
- Structured input preserves the validated provider-neutral question set
and sanitized origin.
- Noncanonical provider request identities are deterministically
projected for PRP while the original identity remains authoritative for
the sidecar resolution command.
- Existing PRP v1 identifiers remain schema-compatible; the only public
ID-schema change widens turn/item limits from 160 to 240 characters. The
internal ACPX sidecar wire schema now mirrors the stable IDs its Rust
transport already enforced.
- The projector verifies event-carried terminal and assistant turn
identifiers against the durable context.
- No production path invokes this projector in this pull request.
Durable command execution remains the next slice.
> 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
- OpenAI Codex with GPT-5.6, agentic 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 linked the preceding public PR or described the issue in-PR
- [x] I have not referenced internal or instance-local Paperclip issues
or links
- [x] My branch name describes the change and contains no internal
Paperclip ticket id
- [ ] 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
## Thinking Path
> - Paperclip Runner now has a complete guarded Codex vertical slice.
> - The next provider series must not start by importing a provider
implementation or dependency bundle.
> - ACPX needs one bounded, versioned process boundary shared by
TypeScript and Rust.
> - A schema is the authority; checked-in generated inventories keep
both languages in lockstep.
> - Unknown versions, commands, event types, and properties must fail
closed.
> - This pull request therefore lands only the sidecar wire contract and
its drift gate.
> - No ACPX runtime, dependency, executable, package export, or
production selection is added.
## Linked Issues or Issue Description
This is the first package-local unit in the post-Codex provider series.
**What happened?**
The integration branch contains an ACPX provider, but its TypeScript
sidecar and Rust client need a small shared authority before either
implementation can be reviewed safely. Importing the final integration
implementation directly would mix the protocol, runtime, third-party
dependencies, and production wiring.
**Expected behavior**
The schema defines every ACPX sidecar request, response, event, command,
event type, and protocol version. Generated TypeScript and Rust
inventories must drift-check against that schema. No runtime can select
or execute ACPX yet.
**Steps to reproduce**
1. Change the protocol version, command inventory, or event inventory in
the schema.
2. Run the runner protocol type check without regenerating the language
inventories.
3. Observe the drift gate fail.
**Paperclip version or commit**
Stacked on `runner-server-semantic-codex` at `ebd7f9df7`.
## What Changed
- Add the internal ACPX sidecar v2 JSON Schema outside the public PRP v1
schema catalog.
- Generate one TypeScript inventory and one Rust inventory from that
schema.
- Add generate and check hooks to the existing runner protocol-type
workflow.
- Add fail-closed AJV tests for all three message families, version
drift, unknown commands, and extra properties.
- Keep the generated Rust module unregistered until the Rust ACPX
transport exists.
## Compatibility Boundary
- Codex remains the only production runner provider.
- `paperclip_runner` selection and the default-off rollout flag are
unchanged.
- No ACPX package, patch, lockfile, binary entry point, root export,
server file, UI file, workflow, or dependency is added.
- The schema is shipped with the existing `protocol` directory but is
not added to the public PRP manifest.
- Existing direct adapters continue through their current paths.
- Diff against the actual stacked base: 6 files.
## Verification
- Runner TypeScript typecheck and both generated-contract drift gates —
passed.
- Runner TypeScript tests — 37 files and 355 Vitest tests passed; 11
Node contract tests passed.
- Rust provider-bridge regression suite after restacking — 14/14 passed.
- `pnpm -r typecheck` — passed for all applicable workspaces.
- `pnpm build` — passed, including runner binary, server, UI, and
workspace packages.
- `pnpm test:run` — attempted; the local host reproduced unrelated
workspace/Postgres and port-exposure failures in unchanged server
suites. The changed runner contract suites pass, and the repository's
serialized/sharded GitHub checks remain authoritative for those
host-sensitive suites.
- Prettier, rustfmt, generated-source drift checks, and `git diff
--check` — passed.
- `pnpm-lock.yaml` is unchanged.
## Risks
The main risk is allowing schema and generated language inventories to
diverge. Build and typecheck now fail on any drift. The sidecar
implementation and third-party ACPX packages are deliberately absent, so
this PR cannot alter runtime behavior or expand the production attack
surface.
## Model Used
OpenAI Codex with GPT-5 and repository tool use.
## 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
- [x] I have described the issue and expected behavior in this PR
- [x] I have not referenced internal or instance-local Paperclip issues
or links
- [x] My branch name describes the change and contains no internal task
identifier
- [x] I have run the affected tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] I have documented the compatibility and security boundary
- [ ] All applicable GitHub Actions are green
- [ ] Greptile is 5/5 with every actionable comment resolved
- [x] I will address all review findings before requesting merge
Dotta