feat: added IPython-backed Python tool with streaming output and Jupyter integration

- Added IPython-backed Python tool with streaming output and image/JSON rendering.
- Implemented Jupyter kernel gateway integration with WebSocket communication.
- Added Python prelude with 30+ shell-like utility functions for file operations.
- Migrated environment variables from PI_ to OMP_ prefix with automatic migration.
- Added streaming output system with automatic spill-to-disk for large outputs.
- Reorganized settings interface into behavior, tools, display, voice, status, lsp, and exa tabs.

packages/coding-agent/docs/python-repl.md

@@ -0,0 +1,77 @@
+# Python REPL (Jupyter Kernel Gateway)
+
+## Requirements
+
+- Python 3 available on PATH (or via an active virtualenv)
+- `jupyter-kernel-gateway` (`kernel_gateway` module) and `ipykernel` installed in the selected Python environment
+
+Install:
+```bash
+python -m pip install jupyter_kernel_gateway ipykernel
+```
+
+## How It Works
+
+The Python tool starts a Jupyter Kernel Gateway process locally, which manages an IPython kernel. All code execution goes through the gateway's REST and WebSocket APIs.
+
+Startup flow:
+1. Spawn `python -m kernel_gateway` on a random available port
+2. Wait for gateway to become ready (`GET /api/kernelspecs`)
+3. Create a kernel (`POST /api/kernels`)
+4. Connect WebSocket for execution messages
+5. Run prelude code (helper functions)
+
+## External Gateway Support
+
+Instead of spawning a local gateway, you can connect to an already-running Jupyter Kernel Gateway:
+
+```bash
+# Connect to external gateway
+export OMP_PYTHON_GATEWAY_URL="http://127.0.0.1:8888"
+
+# Optional: auth token if gateway requires it (KG_AUTH_TOKEN)
+export OMP_PYTHON_GATEWAY_TOKEN="your-token-here"
+```
+
+When `OMP_PYTHON_GATEWAY_URL` is set:
+- No local gateway process is spawned
+- Kernels are created on the external gateway
+- The gateway process is not killed on shutdown
+- Availability check uses `/api/kernelspecs` endpoint instead of local module check
+
+This is useful for:
+- Remote kernel execution
+- Shared kernel environments
+- Pre-configured gateway setups
+
+## Environment Propagation
+
+- The kernel inherits a filtered environment (explicit allowlist + denylist)
+- `PYTHONPATH` includes the working directory and any existing `PYTHONPATH` value
+- Virtual environments are detected via `VIRTUAL_ENV`, `.venv/`, or `venv/` and preferred when present
+
+## Kernel Modes
+
+Settings under `python` control exposure and reuse:
+- `toolMode`: `ipy-only` (default), `bash-only`, `both`
+- `kernelMode`: `session` (default, queued), `per-call`
+
+## Shell Bridge
+
+The Python prelude exposes `bash()` which:
+- Sources the shell snapshot when `OMP_SHELL_SNAPSHOT` is set
+- Runs via `bash -lc` when available, with OS fallbacks
+
+## Output Handling
+
+- Streams `stdout`/`stderr` as text
+- `image/png` display data renders inline in TUI
+- `application/json` display data renders as a collapsible tree
+- `text/html` display data is converted to basic markdown
+
+## Troubleshooting
+
+- **Kernel unavailable**: Ensure `python` + `jupyter-kernel-gateway` + `ipykernel` are installed; the session will fall back to bash-only.
+- **External gateway unreachable**: Check the URL is correct and the gateway is running. If auth is required, set `OMP_PYTHON_GATEWAY_TOKEN`.
+- **IPC tracing**: Set `OMP_PYTHON_IPC_TRACE=1` to log kernel message flow.
+- **Stdin requests**: Interactive input is not supported; refactor code to avoid `input()` or provide data programmatically.