The tool is named codemode again and scripts configure it with a first-line // @options: {...} instead of the // @exec: pragma. yield_time_ms is gone; max_output_tokens and timeout_ms remain. Comments, docs, and tests no longer describe the tool in terms of another agent.
The agent loop is back to main's tool execution: it only exports runToolCall(), honors isError results, and passes structuredContent through afterToolCall. Nested calls (ctx.executeTool, ids, events with parentToolCallId, the nestedCalls record) live in coding-agent and start on the first call.
AgentSession no longer knows exec or tool_search. Tools adjust the declared loadout through a generic prepareLoadout hook, and codemode and tool_search use it like any other tool.
exec and tool_search move to built-in extensions under src/extensions/ and register inactive (defaultActive: false). The CLI loads them with MCP; SDK sessions add createCodemodeExtension(), createToolSearchExtension(), and createMcpExtension(). Extensions gain pi.getSettings() and model catalog and classifier access on ModelRegistry.
The codemode tool is now exec and follows the exec tool of OpenAI Codex, so scripts written for Codex run unchanged:
- // @exec: pragma with yield_time_ms, max_output_tokens (default 10000 tokens) and the pi addition timeout_ms; Codex's grammar and error messages
- text(), image() (data URLs, { image_url }, MCP ImageContent), exit(), ALL_TOOLS, tools under normalized identifiers; console and return values append text
- Results start with Script completed/failed and the wall time; failed scripts return an error result that keeps partial output and appends Script error
- Output over the token budget keeps its start and end like Codex; the full text is spilled to a temp file
- MCP tools resolve to their CallToolResult (isError resolves) and are declared as CallToolResult<T>; bash resolves to { output, exit_code, wall_time_seconds }, also for non-zero exits
- The description uses Codex's layout: helper list, deferred-tool guidance, shared MCP types, one section per tool grouped by namespace (MCP servers, with their instructions)
