Disable CDP proxy compression

[rgarcia]

Summary

• Disable websocket permessage-deflate for both legs of the CDP proxy.
• Add an e2e benchmark for repeated Page.captureScreenshot calls through the built headless image.

Benchmark results

Command:

go test -run '^$' -bench '^BenchmarkCDPCaptureScreenshot$' -benchtime=20x -count=1 -v ./e2e

Image was rebuilt before each benchmark:

DOCKER_BUILDKIT=1 docker build -f images/chromium-headless/image/Dockerfile -t onkernel/chromium-headless-test:latest .

Proxy compression	Result	Throughput	Payload
Enabled (CompressionContextTakeover)	302.5ms/op	4.674 screenshot_MiB/s	1,482,564 screenshot_bytes/op
Disabled (CompressionDisabled)	236.7ms/op	5.974 screenshot_MiB/s	1,482,564 screenshot_bytes/op

Disabling compression improved this screenshot benchmark by roughly 22% latency / 1.28x throughput.

Test plan

• go test -run '^$' -bench '^$' ./e2e
• go test ./lib/devtoolsproxy
• Rebuilt onkernel/chromium-headless-test:latest
• Ran BenchmarkCDPCaptureScreenshot before and after disabling proxy compression

Made with Cursor

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Note

Low Risk
Proxy-only transport change with no auth or API surface changes; tradeoff is higher wire size on compressible traffic in exchange for lower CPU/latency on large CDP messages.

Overview
Turns off permessage-deflate on both the client-facing and upstream WebSocket legs in devtoolsproxy (CompressionDisabled instead of CompressionContextTakeover), so CDP traffic—including large base64 screenshot payloads—is no longer compressed in the proxy path.

Adds BenchmarkCDPCaptureScreenshot in e2e: Docker headless container, CDP target setup, repeated Page.captureScreenshot, and custom metrics (screenshot_bytes/op, screenshot_MiB/s) to track proxy screenshot performance over time.

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[hiroTamada]

lgtm. clean two-line proxy change + well-scoped e2e benchmark. trade-off (CPU/latency for wire bytes) is the right call for screenshot-heavy CDP workloads; worth keeping an eye on JSON-heavy traffic over slow links.