Session Closeout: Browser Agent CDP Enhancements (2026-04-25)

Context

Continued from prior session that migrated browser-agent from Tampermonkey to MV3 extension (v2.0.0). This session added CDP (Chrome DevTools Protocol) enhancements to solve FB Marketplace automation challenges: CSP-blocked eval, timer throttling on unfocused tabs, and React event delegation issues.

What Was Built

  • cdpEval — Run arbitrary JS via CDP Runtime.evaluate, bypasses Content Security Policy on Facebook/Google Photos/Deepgram
  • cdpKeys — Send special keystrokes (ArrowDown, Enter, Tab, Escape) via CDP Input.dispatchKeyEvent
  • mouseMoved in CDP click — React event delegation requires mouseMoved before mousePressed for dialog item clicks to register
  • Fixed double character insertion — CDP keyDown with text + char event both inserted characters; removed text from keyDown

Key Discovery: FB Category Picker

FB Marketplace Category field is a dialog picker (not autocomplete). Clicking the combobox opens a scrollable dialog with [role=”button”] items organized by section. Must click the button element, not the text. Condition field IS a standard dropdown with [role=”option”] elements.

Result

Successfully posted FB Marketplace listing (Eufy Smart Scale, $10) using all-CDP workflow. Extension version bumped from 2.0.0 to 2.2.0.

Commits

  • 2b2634c — Add cdpEval and cdpKeys commands
  • fc396eb — v2.1.0: mouseMoved in CDP click
  • 501be8d — v2.2.0: fix double char insertion
  • 531cff4 — Doc updates

Open Items

  • Update fb-marketplace-poster to use CDP commands for category selection
  • Add –await flag to cdp-eval CLI for promise support
  • Consider routing content script polling through background worker to bypass timer throttling

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