codex-app-server-client

Shared in-process app-server client used by conversational CLI surfaces:

• codex-exec
• codex-tui

Purpose

This crate centralizes startup and lifecycle management for an in-process codex-app-server runtime, so CLI clients do not need to duplicate:

• app-server bootstrap and initialize handshake
• in-memory request/event transport wiring
• lifecycle orchestration around caller-provided startup identity
• graceful shutdown behavior

Startup identity

Callers pass both the app-server SessionSource and the initialize client_info.name explicitly when starting the facade.

That keeps thread metadata (for example in thread/list and thread/read) aligned with the originating runtime without baking TUI/exec-specific policy into the shared client layer.

Transport model

The in-process path uses typed channels:

• client -> server: ClientRequest / ClientNotification
• server -> client: InProcessServerEvent
  • ServerRequest
  • ServerNotification
  • LegacyNotification

JSON serialization is still used at external transport boundaries (stdio/websocket), but the in-process hot path is typed.

Typed requests still receive app-server responses through the JSON-RPC result envelope internally. That is intentional: the in-process path is meant to preserve app-server semantics while removing the process boundary, not to introduce a second response contract.

Bootstrap behavior

The client facade starts an already-initialized in-process runtime, but thread bootstrap still follows normal app-server flow:

• caller sends thread/start or thread/resume
• app-server returns the immediate typed response
• richer session metadata may arrive later as a SessionConfigured legacy event

Surfaces such as TUI and exec may therefore need a short bootstrap phase where they reconcile startup response data with later events.

Backpressure and shutdown

• Queues are bounded and use DEFAULT_IN_PROCESS_CHANNEL_CAPACITY by default.
• Full queues return explicit overload behavior instead of unbounded growth.
• shutdown() performs a bounded graceful shutdown and then aborts if timeout is exceeded.

If the client falls behind on event consumption, the worker emits InProcessServerEvent::Lagged and may reject pending server requests so approval flows do not hang indefinitely behind a saturated queue.