Playwright browser streaming for agents

[selfcontained]

Summary

• Adds implementation plan for enabling agents to stream their Playwright browser session as a live MJPEG video feed in the Dispatch UI
• Agent makes one call (dispatch-stream start --playwright <port>), backend handles everything via CDP Page.startScreencast
• Validated at ~37 FPS with ~13KB JPEG frames, zero additional npm dependencies (Node 25 native WebSocket)

Key design decisions

• MJPEG over HTTP — browsers render natively in <img> tags, zero frontend complexity
• No DB changes — stream state is in-memory Map
• Server-driven capture — agent only calls once, backend runs the CDP loop independently
• iOS Simulator streaming planned as follow-up (validated at ~4.5 FPS via subprocess loop)

Implementation scope (docs only for now)

See docs/playwright-streaming-plan.md for the full plan covering:

• src/stream-manager.ts (new) — CDP WebSocket consumer + MJPEG multiplexer
• src/server.ts — new stream routes, SSE events, hasStream injection
• bin/dispatch-stream (new) — shell script for agents
• Frontend — live mode toggle + pulsing LIVE badge in media sidebar

Test plan

• Implementation PR(s) to follow

🤖 Generated with Claude Code