Document host browser tab reuse workflow

Update the Browser tool prompt and plugin DOX so agents list and activate existing tabs by URL or title before opening new host-browser tabs.

Alessandro committed Jun 3, 2026 at 03:45 UTC d871b2e0d7a87acc42afff1ea9dbecec34b7f45d

2 files changed +3 -1

plugins/AGENTS.md

@@ -48,6 +48,7 @@

48 - Keep plugin README and docs current when user-visible plugin behavior changes.

49 - Check configuration before injecting setup or discovery banners so configured plugins do not keep advertising setup.

50 - Use highly unique banner IDs prefixed by plugin name.

51 +- Browser tool prompts must preserve the existing-tab workflow: when a user refers to an already-open URL, tab, or page title, guide agents to `list` and then `set_active` or `navigate` by `browser_id` instead of blindly opening a new tab.

52 - When preparing community plugins, keep plugin contents at the standalone repository root with `plugin.yaml`, `README.md`, and a root `LICENSE`.

53 - Plugin Index submissions use a separate `index.yaml` under `a0-plugins/plugins/<name>/`; do not confuse it with runtime `plugin.yaml`.

plugins/_browser/prompts/agent.system.tool.browser.md

+2 -1

@@ -14,7 +14,8 @@ Actions: `open`, `list`, `state`, `set_active`, `navigate`, `back`, `forward`, `

14 Common args: `action`, `browser_id`, `url`, `ref`, `target_ref`, `text`, `selector`, `selectors`, `script`, `modifiers`, `keys`, `key`, `include_content`, `focus_popup`, `event_type`, `x`, `y`, `to_x`, `to_y`, `delta_x`, `delta_y`, `button`, `quality`, `full_page`, `path`, `paths`, `value`, `values`, `checked`, `width`, `height`, `calls`.

16 Workflow:

17 -- `open` creates a tab and returns id/state.

17 +- `open` creates a tab and returns id/state. In host-browser mode, if the requested URL is already open, the host may reuse and activate that existing tab.

18 +- If the user asks for an existing tab, page title, or already-open URL, call `list` first, match by `title` or `currentUrl`, then use `set_active` or `navigate` on that `browser_id` instead of opening a new tab.

19 - `content` returns markdown with refs like `[link 3]`, `[button 6]`, `[input text 8]`.

20 - Interactions use refs from the latest `content` capture.

21 - For same-page controls that are easier to identify structurally, `click`, `type`, `submit`, `type_submit`, `scroll`, `select_option`, `set_checked`, and `upload_file` may use `selector` instead of `ref`; the tool resolves the selector through `content` first.