Enable git attribution across Codex entry points (#34819)

## What changed

- Install the git attribution extension in the app server, MCP server, and `codex debug prompt-input` so authenticated workspace policy controls the commit and pull request attribution instructions sent to the model.
- Resolve attribution settings from the process-level ChatGPT base URL, independent of per-thread or per-tool configuration overrides.
- Treat git attribution as contextual developer content when mapping model events.

## Testing

- Cover policy fetch retries, workspace switches, rollbacks, cold thread resumes with legacy instructions, MCP tool calls, and prompt-debug output.

GitOrigin-RevId: 57d182c432c20d7c1c6c429057b6163c9f32088d

codex-rs/core/src/event_mapping.rs

@@ -42,6 +42,7 @@ const CONTEXTUAL_DEVELOPER_PREFIXES: &[&str] = &[
     COLLABORATION_MODE_OPEN_TAG,
     MULTI_AGENT_MODE_OPEN_TAG,
     ENVIRONMENTS_INSTRUCTIONS_OPEN_TAG,
+    "<git_attribution>",
     PLUGINS_INSTRUCTIONS_OPEN_TAG,
     REALTIME_CONVERSATION_OPEN_TAG,
     SKILLS_INSTRUCTIONS_OPEN_TAG,

codex-rs/core/src/prompt_debug.rs

@@ -2,6 +2,7 @@ use std::sync::Arc;
 
 use codex_exec_server::EnvironmentManager;
 use codex_exec_server::ExecServerRuntimePaths;
+use codex_extension_api::ExtensionRegistry;
 use codex_extension_api::UserInstructionsProvider;
 use codex_login::AuthManager;
 use codex_protocol::error::CodexErr;
@@ -20,7 +21,6 @@ use crate::state_db_bridge::StateDbHandle;
 use crate::thread_manager::StartThreadOptions;
 use crate::thread_manager::ThreadManager;
 use crate::thread_manager::thread_store_from_config;
-use codex_extension_api::empty_extension_registry;
 
 /// Build the model-visible `input` list for a single debug turn.
 #[doc(hidden)]
@@ -28,6 +28,7 @@ pub async fn build_prompt_input(
     mut config: Config,
     input: Vec<UserInput>,
     state_db: Option<StateDbHandle>,
+    extensions: Arc<ExtensionRegistry<Config>>,
     user_instructions_provider: Arc<dyn UserInstructionsProvider>,
 ) -> CodexResult<Vec<ResponseItem>> {
     config.ephemeral = true;
@@ -56,7 +57,7 @@ pub async fn build_prompt_input(
             .await
             .map_err(|err| CodexErr::Fatal(err.to_string()))?,
         ),
-        empty_extension_registry(),
+        extensions,
         user_instructions_provider,
         /*analytics_events_client*/ None,
         thread_store,