Expose MCP app identity in app context (#29934)

## Why

MCP tool-call events need to expose trusted app identity and action
metadata directly so v2 clients do not have to infer it from tool names
or resource URIs.

## What changed

- Add optional `appName`, `templateId`, and `actionName` fields to MCP
tool-call `appContext`.
- Populate `appName` and `templateId` from trusted Codex Apps metadata,
and derive `actionName` from the trusted app resource metadata.
- Preserve all three fields through core events, legacy protocol events,
persisted thread history, resume redaction, and app-server v2 responses.
- Document the public `appContext` fields in
`codex-rs/app-server/README.md`.
- Regenerate app-server JSON and TypeScript schemas and add coverage for
serialization, persistence, redaction, and metadata propagation.

## Validation

- `just test -p codex-app-server-protocol mcp_tool_call`
- `just test -p codex-core
mcp_tool_call_item_metadata_only_trusts_codex_apps_identity
mcp_tool_call_item_includes_app_identity`
- `just write-app-server-schema`

---------

Co-authored-by: Martin Au-Yeung <280153141+martinauyeung-oai@users.noreply.github.com>

codex-rs/core/src/mcp_tool_call.rs

@@ -326,6 +326,9 @@ struct McpToolCallItemMetadata {
     connector_id: Option<String>,
     link_id: Option<String>,
     mcp_app_resource_uri: Option<String>,
+    app_name: Option<String>,
+    template_id: Option<String>,
+    action_name: Option<String>,
     plugin_id: Option<String>,
 }
 
@@ -342,6 +345,15 @@ impl McpToolCallItemMetadata {
             link_id: trusted_mcp_app_metadata.and_then(|metadata| metadata.link_id.clone()),
             mcp_app_resource_uri: metadata
                 .and_then(|metadata| metadata.mcp_app_resource_uri.clone()),
+            app_name: trusted_mcp_app_metadata.and_then(|metadata| metadata.connector_name.clone()),
+            template_id: trusted_mcp_app_metadata.and_then(|metadata| metadata.template_id.clone()),
+            action_name: trusted_mcp_app_metadata
+                .and_then(|metadata| metadata.codex_apps_meta.as_ref())
+                .and_then(|meta| meta.get(MCP_TOOL_RESOURCE_URI_META_KEY))
+                .and_then(serde_json::Value::as_str)
+                .and_then(|resource_uri| resource_uri.trim_matches('/').rsplit('/').next())
+                .filter(|action_name| !action_name.is_empty())
+                .map(str::to_string),
             plugin_id: metadata.and_then(|metadata| metadata.plugin_id.clone()),
         }
     }
@@ -881,6 +893,9 @@ async fn notify_mcp_tool_call_started(
         connector_id: item_metadata.connector_id,
         mcp_app_resource_uri: item_metadata.mcp_app_resource_uri,
         link_id: item_metadata.link_id,
+        app_name: item_metadata.app_name,
+        template_id: item_metadata.template_id,
+        action_name: item_metadata.action_name,
         plugin_id: item_metadata.plugin_id,
         status: McpToolCallStatus::InProgress,
         result: None,
@@ -923,6 +938,9 @@ async fn notify_mcp_tool_call_completed(
         connector_id: item_metadata.connector_id,
         mcp_app_resource_uri: item_metadata.mcp_app_resource_uri,
         link_id: item_metadata.link_id,
+        app_name: item_metadata.app_name,
+        template_id: item_metadata.template_id,
+        action_name: item_metadata.action_name,
         plugin_id: item_metadata.plugin_id,
         status,
         result,
@@ -999,6 +1017,7 @@ pub(crate) struct McpToolApprovalMetadata {
     tool_title: Option<String>,
     tool_description: Option<String>,
     mcp_app_resource_uri: Option<String>,
+    template_id: Option<String>,
     codex_apps_meta: Option<serde_json::Map<String, serde_json::Value>>,
     openai_file_input_params: Option<Vec<String>>,
 }
@@ -1009,6 +1028,8 @@ const MCP_TOOL_LINK_ID_META_KEY: &str = "link_id";
 const MCP_TOOL_PLUGIN_ID_META_KEY: &str = "plugin_id";
 const MCP_TOOL_THREAD_ID_META_KEY: &str = "threadId";
 const MCP_TOOL_CONNECTED_ACCOUNT_EMAIL_META_KEY: &str = "connected_account_email";
+const MCP_TOOL_TEMPLATE_ID_META_KEY: &str = "template_id";
+const MCP_TOOL_RESOURCE_URI_META_KEY: &str = "resource_uri";
 
 async fn custom_mcp_tool_approval_mode(
     sess: &Session,
@@ -1531,6 +1552,11 @@ pub(crate) async fn lookup_mcp_tool_metadata(
         tool_title: tool_info.tool.title,
         tool_description: tool_info.tool.description.map(std::borrow::Cow::into_owned),
         mcp_app_resource_uri: get_mcp_app_resource_uri(tool_info.tool.meta.as_deref()),
+        template_id: codex_apps_meta
+            .as_ref()
+            .and_then(|meta| meta.get(MCP_TOOL_TEMPLATE_ID_META_KEY))
+            .and_then(serde_json::Value::as_str)
+            .map(str::to_string),
         codex_apps_meta,
         // Disallow custom MCPs from uploading files via fileParams.
         openai_file_input_params: openai_file_input_params_for_server(