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Browser Extension

By symptom.

Likely causeAction
Ghast Desktop not runningOpen Ghast Desktop
Wrong port or token in the extension's Options pageRe-copy from Settings → Integrations → Browser, paste into Options
Port collision with another local serviceSettings → Integrations → Browser → change port; update Options
Token rotated on the desktop sideRe-paste the new token
Sign-out wiped the vault keySign back in on the desktop
Likely causeAction
Auth subprotocol mismatch (rare)Reload the extension (chrome://extensions → refresh icon)
Network filter blocking localhost WebSocketTest with wscat -c ws://127.0.0.1:18189/v1/browser/stream

Agent can't see open tabs

Likely causeAction
Extension not attachedPopup → Attach Current Tab
Tabs in incognitoManifest V3 + debugger isn't allowed in incognito by default; enable extension in incognito if needed
Other extension holds the debugger exclusivelyDetach the other one; only one debugger per tab

Click / type on a selector does nothing

Likely causeAction
Selector doesn't match anything on the pageThe agent should fall back to DOM summarisation; check the tool call result
Element is in a Shadow DOMSome shadow roots are not traversed by default; the agent may need an explicit shadow path
Page has a CSP that blocks evaluated JSCDP can sometimes bypass via isolated worlds; if it fails, screenshot-based interaction is the fallback

Screenshots come back blank

Likely causeAction
Tab isn't fully loaded yetRetry; the agent has a wait helper
Tab is showing protected content (e.g. some video DRM)Some pages reject Page.captureScreenshot; rare

"Reconnect" button doesn't help

Likely causeAction
Service worker is stuckchrome://extensions → service worker → Inspect → reload page
Chrome itself needs a restartQuit Chrome fully (Cmd-Q), relaunch

Manifest auto-load (Option A) fails

Likely causeAction
Chrome not installed at standard pathInstall Chrome or use Option B (manual unpacked load)
Chrome refuses --load-extension (some enterprise policies)Check chrome://policy; manual load may still work in some configurations

After updating Ghast, the extension version is stale

Likely causeAction
Manually loaded extension wasn't reloadedchrome://extensions → refresh icon on the Ghast extension
Auto-launched Chrome was kept open across the updateQuit Chrome, relaunch via the Ghast Settings auto-launch button