Discover available Jupyter kernel specs and project venvs.

Returns a list of dicts with keys: name, display_name, language, source. Use the "name" value as the kernel_name argument to kernel_start.

If scan_dir is provided, also checks for a .venv with ipykernel installed at that path and includes it as a "venv:" entry.

Start a kernel by name, as returned by kernel_discover.

kernel_name is either a registered Jupyter spec name (e.g. "python3") or a venv reference ("venv:/path/to/project") from kernel_discover.

cwd sets the working directory. Defaults to the venv project dir for venv kernels, or the user's home directory for registered specs.

Only one kernel can run at a time — call kernel_stop first if one is already running.

Return the current kernel status.

Returns a dict with: running, alive, project_dir, connection_file, python, pending_executions, transport, ip, shell_port, iopub_port. Returns {"running": False} if no kernel is running.

Stop the running kernel and clean up resources.

Restart the kernel, clearing all variables, imports, and state.

Pending executions are discarded. The kernel process is replaced but the connection is preserved — no need to call kernel_start again.

Interrupt the running kernel (send SIGINT).

Use this to cancel a long-running execution without losing kernel state.

Execute code on the running kernel and return structured output.

Output is returned as tagged text blocks: [stdout], [stderr], [result] (last expression value), [error] (with traceback), plus image blocks for plots and display calls.

If timeout is set and execution exceeds it, returns any output collected so far plus a [pending] block with a msg_id. Pass that msg_id to kernel_get_output to retrieve the rest. Without timeout, blocks until done.

Retrieve output for a pending execution by msg_id.

If still running, waits up to timeout seconds (or returns immediately if timeout is omitted). Returns the same tagged blocks as kernel_execute: [stdout], [stderr], [result], [error], images, and [pending] if not yet done.

Once complete output is returned, the record is cleaned up — calling again with the same msg_id will return an error.