[5/8] Rename Python SDK package to openai-codex (#21905)

## Why

The SDK should publish under the reserved public distribution name
`openai-codex`, and its import module should match that name in the
Python style. Since package names can contain hyphens but import modules
cannot, the public import path becomes `openai_codex`.

Keeping the rename separate from the public API surface change makes the
naming change easy to review and avoids mixing it with API curation.

## What

- Rename the SDK distribution from `openai-codex-app-server-sdk` to
`openai-codex`.
- Rename the import package from `codex_app_server` to `openai_codex`.
- Keep the runtime wheel as the separate `openai-codex-cli-bin`
dependency.
- Update docs, examples, notebooks, artifact scripts, lockfile metadata,
and tests for the new distribution/module names.

## Stack

1. #21891 `[1/8]` Pin Python SDK runtime dependency
2. #21893 `[2/8]` Generate Python SDK types from pinned runtime
3. #21895 `[3/8]` Run Python SDK tests in CI
4. #21896 `[4/8]` Define Python SDK public API surface
5. This PR `[5/8]` Rename Python SDK package to `openai-codex`
6. #21910 `[6/8]` Add high-level Python SDK approval mode
7. #22014 `[7/8]` Add Python SDK app-server integration harness
8. #22021 `[8/8]` Add Python SDK Ruff formatting

## Verification

- Updated package metadata and public API tests to assert the
distribution and import names.

Co-authored-by: Codex <noreply@openai.com>

sdk/python/src/openai_codex/_message_router.py

@@ -0,0 +1,160 @@
+from __future__ import annotations
+
+import queue
+import threading
+from collections import deque
+
+from .errors import AppServerError, map_jsonrpc_error
+from .generated.notification_registry import notification_turn_id
+from .models import JsonValue, Notification, UnknownNotification
+
+ResponseQueueItem = JsonValue | BaseException
+NotificationQueueItem = Notification | BaseException
+
+
+class MessageRouter:
+    """Route reader-thread messages to the SDK operation waiting for them.
+
+    The app-server stdio transport is a single ordered stream, so only the
+    reader thread should consume stdout. This router keeps the rest of the SDK
+    from competing for that stream by giving each in-flight JSON-RPC request
+    and active turn stream its own queue.
+    """
+
+    def __init__(self) -> None:
+        """Create empty response, turn, and global notification queues."""
+        self._lock = threading.Lock()
+        self._response_waiters: dict[str, queue.Queue[ResponseQueueItem]] = {}
+        self._turn_notifications: dict[str, queue.Queue[NotificationQueueItem]] = {}
+        self._pending_turn_notifications: dict[str, deque[Notification]] = {}
+        self._global_notifications: queue.Queue[NotificationQueueItem] = queue.Queue()
+
+    def create_response_waiter(self, request_id: str) -> queue.Queue[ResponseQueueItem]:
+        """Register a one-shot queue for a JSON-RPC response id."""
+
+        waiter: queue.Queue[ResponseQueueItem] = queue.Queue(maxsize=1)
+        with self._lock:
+            self._response_waiters[request_id] = waiter
+        return waiter
+
+    def discard_response_waiter(self, request_id: str) -> None:
+        """Remove a response waiter when the request could not be written."""
+
+        with self._lock:
+            self._response_waiters.pop(request_id, None)
+
+    def next_global_notification(self) -> Notification:
+        """Block until the next notification that is not scoped to a turn."""
+
+        item = self._global_notifications.get()
+        if isinstance(item, BaseException):
+            raise item
+        return item
+
+    def register_turn(self, turn_id: str) -> None:
+        """Register a queue for a turn stream and replay early events."""
+
+        turn_queue: queue.Queue[NotificationQueueItem] = queue.Queue()
+        with self._lock:
+            if turn_id in self._turn_notifications:
+                return
+            # A turn can emit events immediately after turn/start, before the
+            # caller receives the TurnHandle and starts streaming.
+            pending = self._pending_turn_notifications.pop(turn_id, deque())
+            self._turn_notifications[turn_id] = turn_queue
+        for notification in pending:
+            turn_queue.put(notification)
+
+    def unregister_turn(self, turn_id: str) -> None:
+        """Stop routing future turn events to the stream queue."""
+
+        with self._lock:
+            self._turn_notifications.pop(turn_id, None)
+
+    def next_turn_notification(self, turn_id: str) -> Notification:
+        """Block until the next notification for a registered turn."""
+
+        with self._lock:
+            turn_queue = self._turn_notifications.get(turn_id)
+        if turn_queue is None:
+            raise RuntimeError(f"turn {turn_id!r} is not registered for streaming")
+        item = turn_queue.get()
+        if isinstance(item, BaseException):
+            raise item
+        return item
+
+    def route_response(self, msg: dict[str, JsonValue]) -> None:
+        """Deliver a JSON-RPC response or error to its request waiter."""
+
+        request_id = msg.get("id")
+        with self._lock:
+            waiter = self._response_waiters.pop(str(request_id), None)
+        if waiter is None:
+            return
+
+        if "error" in msg:
+            err = msg["error"]
+            if isinstance(err, dict):
+                waiter.put(
+                    map_jsonrpc_error(
+                        int(err.get("code", -32000)),
+                        str(err.get("message", "unknown")),
+                        err.get("data"),
+                    )
+                )
+            else:
+                waiter.put(AppServerError("Malformed JSON-RPC error response"))
+            return
+
+        waiter.put(msg.get("result"))
+
+    def route_notification(self, notification: Notification) -> None:
+        """Deliver a notification to a turn queue or the global queue."""
+
+        turn_id = self._notification_turn_id(notification)
+        if turn_id is None:
+            self._global_notifications.put(notification)
+            return
+
+        with self._lock:
+            turn_queue = self._turn_notifications.get(turn_id)
+            if turn_queue is None:
+                if notification.method == "turn/completed":
+                    self._pending_turn_notifications.pop(turn_id, None)
+                    return
+                self._pending_turn_notifications.setdefault(turn_id, deque()).append(
+                    notification
+                )
+                return
+        turn_queue.put(notification)
+
+    def fail_all(self, exc: BaseException) -> None:
+        """Wake every blocked waiter when the reader thread exits."""
+
+        with self._lock:
+            response_waiters = list(self._response_waiters.values())
+            self._response_waiters.clear()
+            turn_queues = list(self._turn_notifications.values())
+            self._pending_turn_notifications.clear()
+        # Put the same transport failure into every queue so no SDK call blocks
+        # forever waiting for a response that cannot arrive.
+        for waiter in response_waiters:
+            waiter.put(exc)
+        for turn_queue in turn_queues:
+            turn_queue.put(exc)
+        self._global_notifications.put(exc)
+
+    def _notification_turn_id(self, notification: Notification) -> str | None:
+        """Extract routing ids from known generated payloads or raw unknown payloads."""
+        payload = notification.payload
+        if isinstance(payload, UnknownNotification):
+            raw_turn_id = payload.params.get("turnId")
+            if isinstance(raw_turn_id, str):
+                return raw_turn_id
+            raw_turn = payload.params.get("turn")
+            if isinstance(raw_turn, dict):
+                raw_nested_turn_id = raw_turn.get("id")
+                if isinstance(raw_nested_turn_id, str):
+                    return raw_nested_turn_id
+            return None
+        return notification_turn_id(payload)