Dev Browser Skill

Use dev-browser CLI to run multi-step browser automation with persistent page state.

Defaults

• Prefer multi-step execution: Use one run --code block for multiple actions whenever possible.
• Reuse page names: Keep the same --page name across turns to preserve state.
• Control via daemon commands: Explicitly use ensure/status/stop/clean.
• CLI must be available: Ensure dev-browser command is installed and on PATH (from the separated CLI package).

Setup

If dev-browser command is missing, install CLI globally:

pnpm add -g @jtsang/dev-browser-cli
# or: npm install -g @jtsang/dev-browser-cli

Ensure daemon is running before actions:

dev-browser daemon ensure --mode launch --json
# optional: choose launch engine (default: patchright)
dev-browser daemon ensure --mode launch --engine playwright --json

Use extension mode when user wants their existing Chrome session:

dev-browser daemon ensure --mode extension --json

Useful lifecycle commands:

dev-browser daemon status --json
dev-browser daemon stop --mode launch
dev-browser daemon clean --stale-only
dev-browser doctor

Run Multi-Step Scripts

Use run --code as the primary execution command.

dev-browser run --mode launch --page checkout --json --code '
await page.goto("https://example.com");
await helpers.waitForPageLoad(page);
await page.fill("input[name=email]", "test@example.com");
await page.click("button[type=submit]");
return { url: page.url(), title: await page.title() };
'

Execution Context

--code runs as async JavaScript function body with injected values:

• page – persistent Playwright Page for --page name
• client – dev-browser client instance
• helpers – utility helpers (waitForPageLoad)
• log(entry) – structured step logs collected in output

Output Contract

Success (ok: true) includes:

• mode
• pageName
• data (your returned value)
• logs
• timingMs

Failure (ok: false) includes:

• error.code (RUN_TIMEOUT or RUN_EXEC_ERROR)
• error.message
• error.retryable

Workflow Pattern

For complex tasks:

1. daemon ensure
2. Run one multi-step run --code
3. Evaluate JSON result
4. If needed, run another run --code with same --page
5. On completion, daemon stop (or rely on idle TTL)

Page State Inspection

Use run --code for debugging snapshots/screenshots:

dev-browser run --page debug --json --code '
await page.screenshot({ path: "debug.png", fullPage: true });
const snapshot = await client.getAISnapshot("debug");
return { url: page.url(), title: await page.title(), snapshot };
'

Notes

• run --code accepts JavaScript only (no TypeScript syntax inside code body).
• Same --page name is serialized by lock to prevent concurrent mutation conflicts.
• Runtime data is stored under ~/.dev-browser/ (override with DEV_BROWSER_HOME).