---
name: tau-e2e-testing-tmux
description: Use Tau's dev tmux helper for manual agent-controlled end-to-end testing of the current checkout.
---

# Tau end-to-end testing with tmux

Use the hidden `tau dev tmux` helper to run a manual Tau session in a private
tmux server with isolated scratch state. This is for agent-controlled manual E2E
checks, not an automated test framework.

1. Build the current checkout:
   ```sh
   cargo build -p dpc-tau
   ```
2. Start an isolated tmux session. When `--scratch-root` / `--root` is omitted,
   the helper generates a unique temporary scratch root and prints it in the
   startup output. Copy the printed `scratch root:` value into `scratch_root`
   for later commands:
   ```sh
   target/debug/tau dev tmux start \
     --tau-bin target/debug/tau
   scratch_root='<printed scratch root>'
   ```
   By default this sets scratch `HOME`, `XDG_CONFIG_HOME`, `XDG_STATE_HOME`,
   `XDG_RUNTIME_DIR`, disables all extensions, and enables only `core-shell`
   with its working directory pointed at scratch `work/`. Use `--workdir` only
   for an existing external directory that should not be created or chmodded by
   the helper.

   Provider access is opt-in. If `~/.config/tau/testing.yaml` is absent, start
   prints a warning and copies no real provider credentials/config/state. To let
   the tmux Tau use selected real provider profiles, configure exact provider
   profile names:
   ```yaml
   testing_providers:
     - chatgpt
   ```
   Discover exact profile names in the real Tau environment with
   `tau provider list`; use the displayed profile name, which must match the
   stem of `~/.local/state/tau/auth.d/<provider>.json`.
   The helper copies only `~/.local/state/tau/auth.d/<provider>.json` for those
   names into scratch state and then enables `provider-builtin`; it never copies
   all providers or general user config. For more detail, load the built-in
   self-knowledge skills `tau-self-knowledge-e2e-testing` and
   `tau-self-knowledge-ext-provider-builtin`.
3. Inspect the UI using the printed scratch root:
   ```sh
   target/debug/tau dev tmux capture --scratch-root "$scratch_root"
   ```
4. Send input:
   ```sh
   target/debug/tau dev tmux send --scratch-root "$scratch_root" -- :version
   ```
   Add `--no-enter` to paste without submitting.
5. Stop and clean up:
   ```sh
   target/debug/tau dev tmux stop --scratch-root "$scratch_root" --remove-scratch
   ```

Use `--scratch-root` or its shorter `--root` alias when you need a specific
scratch location. Use `--session`, `--width`, and `--height` when you need a
non-default session name or fixed pane size.