## Why External-agent import should be discoverable and deliberate without blocking startup or claiming the public `codex [PROMPT]` CLI namespace. The slash command keeps the flow local to the interactive TUI and reuses the existing app-server import API. ## What changed - add the user-facing `/import` slash command - detect external-agent importable items only when the command is invoked - run imports through the embedded local app-server - show start and completion messages, refresh configuration, and block duplicate imports while one is pending - reject the flow for unsupported remote and local-daemon sessions ## Validation - `just test -p codex-tui external_agent_config_migration` (10 passed) - manually exercised an isolated TUI fixture with existing external-agent setup and session data using a fresh `CODEX_HOME` - verified picker customization, plugin and session detection, import completion, repeated invocation, and imported-session resume context - the broader `just test -p codex-tui` run passed 2,805 tests, with 2 unrelated guardian feature-flag failures and 4 skipped tests ## Draft follow-ups - review whether completion messaging should remain attached to the initiating chat if the user switches chats during an import - review shutdown semantics for an in-progress background import ## Stack 1. [#27064](https://github.com/openai/codex/pull/27064): remove the startup migration flow 2. [#27065](https://github.com/openai/codex/pull/27065): extract the picker renderer 3. [#27070](https://github.com/openai/codex/pull/27070): add the external-agent import picker UX 4. [#27071](https://github.com/openai/codex/pull/27071): expose the flow through `/import` **This PR is stack item 4.** Draft while the lower stack dependencies are reviewed.
codex-app-server-client
Shared in-process app-server client used by conversational CLI surfaces:
codex-execcodex-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:
InProcessServerEventServerRequestServerNotificationLegacyNotification
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/startorthread/resume - app-server returns the immediate typed response
- richer session metadata may arrive later as a
SessionConfiguredlegacy 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_CAPACITYby 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.