feat: browser automation tool (Playwright)

[kienbui1995]

New browser tool for headless web testing:

Actions: navigate, screenshot, click, type, evaluate JS
How: Generates Playwright script → runs via Node.js → returns text + screenshot
Deps: Requires npm i -g playwright && npx playwright install chromium
Graceful: Clear error messages if playwright/node missing

Closes the biggest competitive gap vs Cursor and Cline.

29 tools, 192 tests.

Summary by CodeRabbit

Release Notes

• New Features
  • Added Browser tool for web automation and headless testing, supporting page navigation, screenshots, element clicking, text input, and JavaScript evaluation.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 0c778cc2-ff6f-457e-8543-5a328341648d

📥 Commits

Reviewing files that changed from the base of the PR and between 045f7b1 and 31562a3.

📒 Files selected for processing (4)

• README.md
• mc/crates/mc-core/src/runtime.rs
• mc/crates/mc-tools/src/registry.rs
• mc/crates/mc-tools/src/spec.rs

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📝 Walkthrough

Walkthrough

A new "browser" tool was added for headless web/UI testing, enabling actions like navigate, screenshot, click, type, and evaluate on web pages. The feature increments the built-in tools count from 28 to 29 across documentation and tests, with runtime dispatch logic and tool specification definitions.

Changes

Cohort / File(s)	Summary
Tool Specification mc/crates/mc-tools/src/spec.rs	Added new browser ToolSpec entry with JSON schema defining required action field (constrained to navigate, screenshot, click, type, evaluate) and optional fields (url, selector, text, script).
Runtime Execution mc/crates/mc-core/src/runtime.rs	Implemented new execute_browser async helper that dispatches browser tool requests, reads action-specific JSON parameters, generates inline Playwright (Node) scripts, executes them via node process, and returns results with error handling for missing fields, missing dependencies, and execution failures.
Documentation & Tests README.md, mc/crates/mc-tools/src/registry.rs	Updated built-in tools count from 28 to 29 in README feature documentation and registry unit test assertion.

Sequence Diagram(s)

sequenceDiagram
    participant Client as Client/Dispatcher
    participant Runtime as Runtime Handler
    participant Script as Script Generator
    participant Node as Node Process
    
    Client->>Runtime: dispatch tool (name="browser")
    activate Runtime
    Runtime->>Runtime: validate action & parameters
    Runtime->>Script: construct Playwright script
    activate Script
    Script->>Script: build action-specific JS code
    Script-->>Runtime: return script content
    deactivate Script
    Runtime->>Runtime: write to /tmp/mc_browser_script.js
    Runtime->>Node: execute via node process
    activate Node
    Node->>Node: run Playwright commands
    Node-->>Runtime: return output
    deactivate Node
    Runtime->>Runtime: parse result & error status
    Runtime-->>Client: return (output, error_flag)
    deactivate Runtime

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Estimated code review effort

🎯 4 (Complex) | ⏱️ ~40 minutes

Poem

🐰 A browser tool hops into the warren today,
With Playwright scripts it web-tests the way,
Twenty-nine tools now stand at the gate,
Navigate, click, and screenshot—it's great!
From rabbit's own paws, the web comes alive! 🌐✨

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/browser-tool

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