Remove the deprecated thread/rollback API (#44915)

## What changed

Remove `thread/rollback`, its request and response types, generated bindings, and the core `Op::ThreadRollback` operation. Requests now follow the generic unknown-method rejection path. Document `thread/revert` as the alternative for paginated threads.

Keep historical `ThreadRolledBack` markers and legacy error deserialization so existing rollouts remain compatible with replay and migration.

## Testing

Adapt retained-context and Guardian history tests to append legacy rollback markers and resume threads, preserving coverage of surviving instructions, answers, and review history.

GitOrigin-RevId: b3da1becdf86b1869275aacb0ffc2817cee5af2e

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

@@ -5833,21 +5833,6 @@ class ThreadRevertedNotification(BaseModel):
     thread_id: Annotated[str, Field(alias="threadId")]
 
 
-class ThreadRollbackParams(BaseModel):
-    model_config = ConfigDict(
-        populate_by_name=True,
-    )
-    num_turns: Annotated[
-        int,
-        Field(
-            alias="numTurns",
-            description="The number of turns to drop from the end of the thread. Must be >= 1.\n\nThis only modifies the thread's history and does not revert local file changes that have been made by the agent. Clients are responsible for reverting these changes.",
-            ge=0,
-        ),
-    ]
-    thread_id: Annotated[str, Field(alias="threadId")]
-
-
 class ThreadSearchSortKey(Enum):
     created_at = "created_at"
     updated_at = "updated_at"
@@ -6815,15 +6800,6 @@ class ThreadApproveGuardianDeniedActionRequest(BaseModel):
     params: ThreadApproveGuardianDeniedActionParams
 
 
-class ThreadRollbackRequest(BaseModel):
-    model_config = ConfigDict(
-        populate_by_name=True,
-    )
-    id: RequestId
-    method: Annotated[Literal["thread/rollback"], Field(title="Thread/rollbackRequestMethod")]
-    params: ThreadRollbackParams
-
-
 class ThreadRevertRequest(BaseModel):
     model_config = ConfigDict(
         populate_by_name=True,
@@ -11767,7 +11743,7 @@ class Thread(BaseModel):
     turns: Annotated[
         list[Turn],
         Field(
-            description="Only populated on `thread/resume`, `thread/rollback`, `thread/fork`, and `thread/read` (when `includeTurns` is true) responses. For all other responses and notifications returning a Thread, the turns field will be an empty list."
+            description="Only populated on `thread/resume`, `thread/fork`, and `thread/read` (when `includeTurns` is true) responses. For all other responses and notifications returning a Thread, the turns field will be an empty list."
         ),
     ]
     updated_at: Annotated[
@@ -11934,18 +11910,6 @@ class ThreadRevertResponse(BaseModel):
     ] = None
 
 
-class ThreadRollbackResponse(BaseModel):
-    model_config = ConfigDict(
-        populate_by_name=True,
-    )
-    thread: Annotated[
-        Thread,
-        Field(
-            description="The updated thread after applying the rollback, with `turns` populated.\n\nThe ThreadItems stored in each Turn are lossy since we explicitly do not persist all agent interactions, such as command executions. This is the same behavior as `thread/resume`."
-        ),
-    ]
-
-
 class ThreadSearchResult(BaseModel):
     model_config = ConfigDict(
         populate_by_name=True,
@@ -12169,7 +12133,6 @@ class ClientRequest(
         | ThreadCompactStartRequest
         | ThreadShellCommandRequest
         | ThreadApproveGuardianDeniedActionRequest
-        | ThreadRollbackRequest
         | ThreadRevertRequest
         | ThreadListRequest
         | ThreadSectionListRequest
@@ -12277,7 +12240,6 @@ class ClientRequest(
         | ThreadCompactStartRequest
         | ThreadShellCommandRequest
         | ThreadApproveGuardianDeniedActionRequest
-        | ThreadRollbackRequest
         | ThreadRevertRequest
         | ThreadListRequest
         | ThreadSectionListRequest