Glass

Glass is a local, revision-safe Chrome automation runtime for agents. It combines semantic observation, verified workflows, MCP, CLI, TUI, and Rust APIs while keeping every browser action explicit and bounded.

Glass controls Chrome or Chromium through the Chrome DevTools Protocol (CDP); it does not include a browser runtime or create an autonomous action plan. Install the executable with Cargo, then use the safe observe → guarded action → verify loop.

Support status

The command-line interface (CLI), terminal user interface (TUI), Model Context Protocol (MCP) server, and Rust library use the same session runtime. The support table describes declared targets and target-specific validation requirements. Native runtime certification is not implied by a source build. See the cross-platform feature parity matrix for implementation inventory and the release evidence guide for the crates.io package and source-only GitHub Release boundary.

Install the local checkout

Prerequisite: install stable Rust and a supported Chrome or Chromium browser.

Run:

cargo install --path . --locked
glass --help

The command builds and installs the local glass executable.

The latest published package can be installed with:

cargo install glass-browser --locked

Use glass install-chromium when no supported system browser is available.

Read Installation and operations for browser discovery, profiles, attach mode, logging, policy, and deployment. See Experimental capabilities before enabling opt-in features.

Run Glass

Start the TUI for a visible session:

glass tui

Enter these commands in the TUI:

navigate https://example.com
observe

Run one operation from the CLI:

glass navigate https://example.com
glass --incognito --headed navigate https://example.com

Compile a bounded Task Protocol plan without starting Chrome:

glass task compile task.json
glass task compile task.json --explain

Validate authored Task Protocol JSON without compiling or starting Chrome:

glass task validate task.json

The canonical plan remains on stdout; --explain writes deterministic, redacted compilation metadata to stderr.

Inspect or diff validated browser-free Web IR drafts:

glass ir validate draft.json
glass ir inspect draft.json
glass ir diff before.json after.json
glass ir diff before.json after.json --summary
glass ir continuity before.json after.json field-1
glass ir canonical draft.json

ir diff prints detailed local diagnostics by default; --summary emits the bounded canonical diff projection used by the protocol helpers.

Use --profile NAME for persistent cookies and storage. Use --incognito for a disposable browser profile.

Interfaces

Experimental extraction and Web IR contracts are available from the Rust crate root (ExtractionRequest, ExtractionEvidence, and GlassWebIrDraft). They are browser-free contract and reconciliation APIs; the native browser extraction runtime is not yet a stable public surface.

Example MCP configuration:

{
  "mcpServers": {
    "glass": {
      "command": "/absolute/path/to/glass",
      "args": ["--mcp"]
    }
  }
}

Use an absolute path when the MCP client does not inherit your shell path. Keep stdout reserved for MCP frames. Read the MCP guide for frame limits, tools, lifecycle, and security.

Main capabilities

Glass provides these browser operations:

• navigate, click, double-click, hover, drag, type, clear, check, uncheck, and select;
• scroll, wait, inspect text, inspect the DOM, evaluate JavaScript, and capture screenshots or PDFs;
• upload files, handle JavaScript dialogs, and dismiss recognized consent controls;
• select page targets and frames;
• inspect and export cookies and web storage;
• run bounded batches and workflows; and
• use revision guards and bounded verification evidence.

Semantic observations provide bounded page and region data. Start with:

glass observe --level summary
glass observe --level interactive

Read the semantic observation guide before using observation references for actions.

Intent resolution compares semantic candidates before an action. Use:

glass resolve-intent request.json
glass execute-intent execution.json

Read the intent resolution guide for evidence, ambiguity, and revision rules.

Glass also includes workflow authoring and reliability checks. Read Workflow authoring and Reliability laboratory.

Targets and revisions

An observation returns bounded accessibility data and revisioned target references such as r7:b42. You can also use explicit locators:

glass click 'name=Save'
glass click 'role=button;name=Save'
glass click 'css=button.primary'

Guard an action with the revision from the observation:

glass click r7:b42 --expected-revision 7
glass type 'hello' --target r7:b43 --expected-revision 7

Glass rejects a stale revision before it sends the browser action. Read the action guide for result fields and recovery.

Rust library and clients

After publication, add the crate as glass:

[dependencies]
glass = { package = "glass-browser", version = "0.2" }

The library provides BrowserSession, session options, policies, observations, revision-safe actions, target and frame management, storage, downloads, screenshots, PDFs, semantic observations, and the MCP server.

The repository-only TypeScript client and Python client remain experimental repository clients for the 0.2.5 development line. They are not published as npm or PyPI packages, do not include a browser runtime, and do not change the primary Cargo installation path.

Safety and scope

Glass requires a local Chrome or Chromium process and a local CDP connection. It does not provide a hosted browser service or Windows support.

Use a dedicated browser profile. Keep the CDP endpoint local. Treat profiles, screenshots, DOM output, cookies, and logs as sensitive. Read the security policy before using authenticated sessions or attach mode.

Documentation

Start with the documentation index. It links to installation, CLI, actions, workflows, MCP, daemon mode, policy, security, architecture, and release guides.

Development

Run the checks before you submit a change:

cargo fmt --all -- --check
cargo test --all-targets --locked
cargo clippy --all-targets --all-features --locked -- -D warnings

Run the browser smoke test only when a supported browser is available:

GLASS_E2E=1 cargo test --test browser_smoke -- --nocapture

License

Glass is licensed under the MIT License.