driving-tauri-apps

Driving Tauri apps with tauri-browser

tauri-browser is a CLI + in-app plugin (tauri-plugin-debug-bridge) that lets an agent drive a running Tauri app: snapshot the DOM with element refs, click/fill, run JS, take screenshots, and call Tauri commands directly. Use plugin + CLI 0.4.1 or newer — it fixed four foundational bugs (see "Old versions" below).

Setup (consuming app)

# src-tauri/Cargo.toml
[dependencies]
tauri-plugin-debug-bridge = { version = "0.4.1", optional = true }
[features]
debug = ["dep:tauri-plugin-debug-bridge"]

// lib.rs
#[cfg(feature = "debug")]
let builder = builder.plugin(tauri_plugin_debug_bridge::init());

Run with pnpm tauri dev --features debug. No capability configuration needed (≥0.4.1 self-grants its ACL permission). The CLI auto-discovers port + token from /tmp/tauri-debug-bridge/; with several live apps, pass --app com.example.id.

Core loop

tauri-browser connect                          # health check; proves the bridge is up
tauri-browser snapshot -i                      # interactive elements with @refs
tauri-browser click @e3                        # by ref, or CSS: click '[title="Send"]'
tauri-browser fill 'textarea' "hello"          # React-safe as of 0.4.1
tauri-browser run-js "return document.title"   # escape hatch for anything else
tauri-browser screenshot out.png               # native WKWebView capture
tauri-browser invoke list_things '{"id":"x"}'  # call a Tauri command directly

The gotchas that actually bite

1. Snapshot refs go stale on re-render. @refs are data-debug-ref attributes assigned at snapshot time; any framework re-render can drop them. Re-snapshot immediately before clicking, or click by CSS selector / run-js element search instead.

2. invoke bypasses the frontend. Data created via invoke lands in the backend, but the app's store (Zustand/Redux/etc.) doesn't know. Either run-js "location.reload()" to re-init, or drive the UI to refetch. Corollary: verify backend effects with another invoke (e.g. list_*), verify UI effects with run-js/screenshot.

3. Verify framework state, not DOM values. After fill, the DOM value can look right while app state didn't update. Probe a state-driven signal instead — e.g. is the submit button enabled: run-js "return !document.querySelector('[title=\"Send\"]').disabled".

4. Waiting on async app work: poll a completion signal in a shell loop rather than sleeping blind:

   for i in $(seq 1 40); do
     done=$(tauri-browser run-js "return document.body.innerText.includes('Suggested follow-ups')" | grep -c true)
     [ "$done" = "1" ] && break; sleep 5
   done
   

5. After changing the plugin or Cargo deps, the dev watcher won't rebuild — it only watches .rs files. touch src-tauri/src/main.rs, then confirm the running binary actually has the change (strings target/debug/app | grep <marker>) before re-testing.

6. Multi-line run-js needs explicit return; single-line expressions are auto-returned. await works (the wrapper is async). Avoid triggering alert/confirm — they block the bridge.

Recipes

Seed demo data through the backend, then drive the UI:

tauri-browser invoke create_notebook '{"title":"Demo"}'          # returns the id
tauri-browser invoke add_source_file '{"notebookId":"...","path":"/abs/file.md"}'
tauri-browser run-js "location.reload()"                          # store refetch
tauri-browser click '[title="Demo"]'                              # navigate to it

Fill a React composer and submit:

tauri-browser fill 'textarea' 'What is blocking our enterprise deals?'
tauri-browser click '[title="Send"]'

Screenshot a specific UI state: drive to the state, confirm it exists (run-js "return !!document.querySelector('[role=dialog]')"), then screenshot. Screenshots are correct even when the window is occluded (≥0.4.1 forces a render pass).

Old versions (pre-0.4.1) — symptoms and workarounds

Symptom	Cause	≥0.4.1	Workaround on old versions
eval/snapshot/invoke time out; connect/screenshot fine	Tauri ACL silently denies the plugin's eval_callback	plugin self-grants at runtime	add "debug-bridge:default" to a capability file (breaks release builds if plugin is feature-gated)
Screenshots miss changes you just made (modal absent)	occluded window returns last composited frame	afterScreenUpdates forces fresh render	focus the app first via osascript, wait ~2s
fill sets the DOM but app state never updates	React's value tracker dedupes the input event	prototype value setter	run-js with Object.getOwnPropertyDescriptor(proto,'value').set.call(el, text) + dispatch input
"Multiple apps detected" with one app running	stale discovery files from exited apps	liveness probe + cleanup	delete dead files in /tmp/tauri-debug-bridge/

Guidelines

• Always connect first; if the bridge is down, nothing else will work and errors mislead.
• Prefer invoke for data setup (fast, deterministic) and real UI interaction for anything you're screenshotting or verifying — the point of driving the UI is exercising the real code path.
• Screenshot verification beats DOM assertions for visual work; read the image, don't trust selectors.