feat: add webp screenshot format from upstream Playwright MCP

[JustasMonkev]

Summary

Resolves #123 by mirroring upstream microsoft/playwright#41152 / commit f3114b3 (merged 2026-07-10): browser_take_screenshot now accepts type: 'webp' alongside png/jpeg.

Changes in src/tools/screenshot.ts:

• Add 'webp' to the type enum and update the default-filename description to {png|jpeg|webp}.
• Match upstream quality handling: quality: 90 only for jpeg; png/webp use browser defaults (upstream: quality: fileType === 'jpeg' ? 90 : undefined).
• Compute the response image contentType as image/${fileType} so webp returns image/webp.

Plus README parameter docs and three new schema/handler tests.

Version bump — maintainer note

WebP is a new Playwright core capability, so the pin moves from 1.61.0 to 1.62.0-alpha-2026-07-10 (the first build containing #41152; latest stable 1.61.1 still types screenshots as "png"|"jpeg" and throws on webp at runtime). If you'd rather not ship a nightly pin, hold this PR until 1.62.0 stable and I/you can swap the pin — the rest of the diff is unchanged. Note npm ls shows a cosmetic invalid flag on @axe-core/playwright's playwright-core >= 1.0.0 peer range because semver prereleases don't satisfy plain ranges; install and tests are unaffected, and it disappears at 1.62.0 stable.

Why it matters

The tool surface had diverged from upstream Playwright MCP: clients could not request WebP screenshots even though upstream browser_take_screenshot now supports them.

Validation

• npm run build, npm run lint (eslint + typecheck) — clean on the alpha.
• npm test — 355 passed / 9 skipped (3 new webp tests).
• End-to-end: launched real Chromium via the bumped playwright, page.screenshot({ type: 'webp' }) produced a valid WebP (RIFF/WEBP magic bytes, 19 KB).
• npm run test:mcp fails identically on main (harness declares tests for non-exposed browser_network_request/browser_drop — pre-existing, tracked by Sync browser MCP tools with upstream Playwright: network response body/headers, evaluate expressions, browser_drop #116), so it's unrelated to this diff.

🤖 Generated with Claude Code

https://claude.ai/code/session_01VNuK5H15LdnhueURhz1rEq

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Generated by Claude Code

Summary by CodeRabbit

• New Features

  • Added WebP support to the screenshot tool.
  • Screenshot results now report the correct image format for PNG, JPEG, and WebP files.
  • JPEG quality settings are applied only to JPEG screenshots.

• Documentation

  • Updated screenshot tool documentation to include WebP as a supported format.

[coderabbitai]

📝 Walkthrough

Walkthrough

Changes

WebP screenshot support

Layer / File(s)	Summary
Screenshot contract and execution src/tools/screenshot.ts, package.json, README.md	The screenshot tool accepts webp, forwards the format to Playwright, applies quality only to JPEG, returns the matching image content type, updates documentation, and bumps Playwright versions.
Screenshot format validation tests/tools-screenshot.test.ts	Tests cover WebP forwarding, format-specific quality handling, and rejection of invalid screenshot types.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related issues

• Sync browser_take_screenshot with upstream Playwright MCP: add webp output format (blocked on Playwright bump) #123 — Covers the requested WebP screenshot support implemented by this pull request.

Possibly related PRs

• JustasMonkev/mcp-accessibility-scanner#99 — Previously extended browser_take_screenshot parameters and their Playwright mapping.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: adding WebP screenshot support from upstream Playwright MCP.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

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• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/kind-mendel-60pvm1

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@package.json`:
- Around line 52-53: Align the `@playwright/test` dependency with playwright and
playwright-core by updating its version to 1.62.0-alpha-2026-07-10 in
package.json, ensuring all Playwright packages resolve to the same version.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 6b6e2e38-2ebd-4fb5-850d-0c4adadd5ea2

📥 Commits

Reviewing files that changed from the base of the PR and between 51c90a7 and 5815519.

⛔ Files ignored due to path filters (1)

• package-lock.json is excluded by !**/package-lock.json

📒 Files selected for processing (4)

• README.md
• package.json
• src/tools/screenshot.ts
• tests/tools-screenshot.test.ts

[coderabbitai]

🗄️ Data Integrity & Integration | 🟠 Major | ⚡ Quick win

@playwright/test version mismatch with playwright/playwright-core.

playwright and playwright-core are bumped to 1.62.0-alpha-2026-07-10, but @playwright/test (Line 61) remains at 1.61.0. This creates a duplicate playwright-core installation in node_modules (1.61.0 via @playwright/test transitive, 1.62.0-alpha direct), which can lead to API mismatches and subtle runtime issues if both are imported in the same process.

🔧 Proposed fix

-		"`@playwright/test`": "1.61.0",
+		"`@playwright/test`": "1.62.0-alpha-2026-07-10",

Also applies to: 61-61

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@package.json` around lines 52 - 53, Align the `@playwright/test` dependency
with playwright and playwright-core by updating its version to
1.62.0-alpha-2026-07-10 in package.json, ensuring all Playwright packages
resolve to the same version.

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 581551918c

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[chatgpt-codex-connector]

Align the Playwright CLI version used by installs

This new nested 1.61.0 copy exists because @playwright/test remains at 1.61.0 while the runtime playwright/playwright-core packages were bumped to 1.62 alpha. I checked the CI workflow, and its browser install step still runs npx playwright install --with-deps chromium; after npm ci npm links the top-level playwright bin from @playwright/test, so that step uses this 1.61 CLI/browser revision while the application imports the 1.62 runtime. In environments that skip postinstall downloads or rely on the explicit install step, launches can hit Playwright's executable-version mismatch; bump @playwright/test to the same version or invoke the root playwright-core CLI.

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