enhancement : Add onboarding validation command (webwright doctor)

@app.command() で示されている CLI 統合ポイントから始め、提案されている webwright/run/doctor.py モジュールと CHECKS 構造を確認します。名前付きの環境、Playwright、設定、ランタイムのチェックを実装し、webwright doctor がセットアップの問題に対する実行可能な修正方法とともに pass/fail の結果を報告するようにします。

Add webwright doctor onboarding validation command

Summary

Add a webwright doctor CLI command that validates local environment setup and provides actionable fixes for common onboarding/runtime issues.

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Current State

Webwright setup currently requires multiple manual steps:

• Python environment setup
• Playwright installation
• Chromium browser installation
• Claude/Codex plugin setup
• API key configuration
• Browser runtime validation

When something is misconfigured, failures often happen later during runtime with limited debugging guidance.

Examples:

• Missing Chromium binaries
• Playwright not installed
• Missing API keys
• Plugin manifest/configuration issues
• Screenshot permission failures

This creates onboarding friction for new contributors and users.

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Desired State

Provide a command:

webwright doctor

that validates the local environment before runtime.

Example output:

Webwright Doctor

[PASS] Python 3.11 detected
[PASS] playwright installed
[FAIL] Chromium missing
       Fix: playwright install chromium

[PASS] OPENAI_API_KEY detected
[FAIL] Claude plugin manifest missing

4/6 checks passed

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Proposed Checks

Environment

• Python version compatibility
• Required package availability
• Writable directories

Playwright

• Playwright installation
• Chromium/browser availability
• Headless launch validation

Configuration

• API key detection
• Plugin manifest detection
• Environment variable validation

Runtime Validation

• Launch browser
• Open simple webpage
• Capture screenshot successfully

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Proposed Implementation

New Module

webwright/run/doctor.py

CLI Integration

@app.command()
def doctor():
    run_doctor()

Suggested Structure

CHECKS = [
    check_python,
    check_playwright,
    check_chromium,
    check_api_keys,
    check_plugins,
    check_screenshot,
]

Optional Enhancements

• --verbose
• --fix
• JSON output mode
• CI compatibility

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Benefits

• Easier onboarding
• Better contributor experience
• Faster debugging
• Fewer duplicate setup issues
• Reduced maintainer support burden

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Scope

This should be relatively self-contained and beginner/intermediate contributor friendly.