Add observation-only model request lifecycle hooks (#55144)

## What changed

- Add `PreModelRequest` and `PostModelRequest` hooks around model request attempts, including retries. Pass model, session, turn, and optional subagent context; report completion, failure, or cancellation with errors and token usage when available.
- Treat hook output as diagnostic data without allowing it to veto requests or alter model context. Wait for synchronous post-request hooks before dispatching tools, while asynchronous hooks allow streaming tool dispatch to continue.
- Apply memory-consolidation hook filtering and expose the new events through configuration, protocol schemas, generated clients, and the hooks browser.

## Testing

Add integration coverage for failures and retries, ignored control directives, cancellation, synchronous and asynchronous tool ordering, interrupted-turn resume and token accounting, and memory-consolidation filtering. Update hook schema fixtures and hooks browser snapshots.

GitOrigin-RevId: 6ed7b39fc8bb94cf467e350d07d97fcc729c21ce

sdk/python/src/openai_codex/generated/v2_all.py

@@ -1984,6 +1984,8 @@ class HookErrorInfo(BaseModel):
 
 
 class HookEventName(Enum):
+    pre_model_request = "preModelRequest"
+    post_model_request = "postModelRequest"
     pre_tool_use = "preToolUse"
     permission_request = "permissionRequest"
     post_tool_use = "postToolUse"
@@ -2422,8 +2424,14 @@ class ManagedHooksRequirements(BaseModel):
         list[ConfiguredHookMatcherGroup], Field(alias="PermissionRequest")
     ]
     post_compact: Annotated[list[ConfiguredHookMatcherGroup], Field(alias="PostCompact")]
+    post_model_request: Annotated[
+        list[ConfiguredHookMatcherGroup] | None, Field(alias="PostModelRequest")
+    ] = []
     post_tool_use: Annotated[list[ConfiguredHookMatcherGroup], Field(alias="PostToolUse")]
     pre_compact: Annotated[list[ConfiguredHookMatcherGroup], Field(alias="PreCompact")]
+    pre_model_request: Annotated[
+        list[ConfiguredHookMatcherGroup] | None, Field(alias="PreModelRequest")
+    ] = []
     pre_tool_use: Annotated[list[ConfiguredHookMatcherGroup], Field(alias="PreToolUse")]
     session_end: Annotated[list[ConfiguredHookMatcherGroup] | None, Field(alias="SessionEnd")] = []
     session_start: Annotated[list[ConfiguredHookMatcherGroup], Field(alias="SessionStart")]