Reasonix ACP snapshot

ACP is a separate interface surface between an editor/client and the Reasonix engine. The pinned source uses NDJSON JSON-RPC 2.0 over stdin/stdout. Requests and notifications may run concurrently, while writes are serialized by a mutex so frames cannot interleave.

An event adapter projects engine events into ACP session/update. When a tool needs approval, the server sends session/request_permission and resolves the client's choice back into a runtime decision. Todos, tool progress, compaction notices, and extension UI each need a projection policy; engine events and ACP events are not assumed to be one-to-one.

Confirmed

• Framing, message-size cap, and request correlation.
• Prompt/cancel concurrency is not blocked by one long-running turn in the read loop.
• Approval requests and session updates have explicit adapters.
• ACP session metadata persists work mode and tool-approval mode.

Still unknown

• Compatibility with specific editor versions.
• Full semantics across disconnect and reconnect.
• Backpressure and memory behavior for large traces.
• Whether permission UI expresses every Reasonix-specific decision accurately.

Claim: reasonix-source-acp. Evidence can be upgraded only after integrating a real ACP client, saving a redacted wire trace, and testing cancellation, approval, and reconnect.