Add in-process app server and wire up exec to use it

codex-rs/Cargo.toml

@@ -4,6 +4,7 @@ members = [
     "ansi-escape",
     "async-utils",
     "app-server",
+    "app-server-client",
     "app-server-protocol",
     "app-server-test-client",
     "debug-client",
@@ -86,6 +87,7 @@ codex-api = { path = "codex-api" }
 codex-artifacts = { path = "artifacts" }
 codex-package-manager = { path = "package-manager" }
 codex-app-server = { path = "app-server" }
+codex-app-server-client = { path = "app-server-client" }
 codex-app-server-protocol = { path = "app-server-protocol" }
 codex-app-server-test-client = { path = "app-server-test-client" }
 codex-apply-patch = { path = "apply-patch" }

codex-rs/app-server-client/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "codex-app-server-client"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[lib]
+name = "codex_app_server_client"
+path = "src/lib.rs"
+
+[lints]
+workspace = true
+
+[dependencies]
+codex-app-server = { workspace = true }
+codex-app-server-protocol = { workspace = true }
+codex-arg0 = { workspace = true }
+codex-core = { workspace = true }
+codex-feedback = { workspace = true }
+codex-protocol = { workspace = true }
+serde = { workspace = true }
+serde_json = { workspace = true }
+tokio = { workspace = true, features = ["sync", "time", "rt"] }
+toml = { workspace = true }
+tracing = { workspace = true }
+
+[dev-dependencies]
+pretty_assertions = { workspace = true }
+serde_json = { workspace = true }
+tokio = { workspace = true, features = ["macros", "rt-multi-thread"] }

codex-rs/app-server-client/README.md

@@ -0,0 +1,67 @@
+# 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.