#19766: fix: Chrome relay extension auto-reattach after SPA navigation

## Summary Fixes #19744 — The Chrome Browser Relay extension loses its CDP connection after any click that triggers SPA in-page navigation (Gmail, Google Calendar, etc.), making it effectively read-only for SPAs. ## Root Cause `onDebuggerDetach` in `background.js` unconditionally calls `detachTab()` on any debugger detach event — including navigations where the tab still exists. It never attempts to re-attach, so the connection is permanently lost until the user manually clicks the extension badge again. ## Changes **Core fix — `onDebuggerDetach` rewritten:** - Detects navigation vs tab close (checks if tab still exists via `chrome.tabs.get`) - Skips re-attach for `chrome://` and extension pages - Sends `Target.detachedFromTarget` for old session before re-attaching (clean session handoff) - **3 retries with exponential backoff** (300ms → 700ms → 1500ms) to handle varying page load times - Each retry verifies: tab exists, relay connected, re-attach not cancelled by user - Logs at each step for debugging (`chrome://extensions` service worker console) **Race condition fixes:** - `reattachPending` Set prevents concurrent re-attach loops for the same tab - `connectOrToggleForActiveTab`: if user clicks badge during re-attach, cancels cleanly - `onRelayClosed`: clears `reattachPending` so in-flight retries bail out immediately **New: `chrome.tabs.onRemoved` listener:** - Original code had no handler for tab removal — could leave stale state - Now cleans up both `reattachPending` and `tabs` map on tab close ## Testing Tested with: - Gmail (clicking emails in inbox triggers SPA navigation) - Google Calendar (navigating between days/weeks) - Tabs that are closed during re-attach retry window - User toggling badge during re-attach ## Files Changed - `assets/chrome-extension/background.js` — 143 insertions, 2 deletions <!-- greptile_comment --> <h3>Greptile Summary</h3> This PR fixes the Chrome Browser Relay extension losing its CDP connection after SPA in-page navigations (Gmail, Google Calendar, etc.) by rewriting `onDebuggerDetach` to detect whether the tab still exists and attempt automatic re-attachment with exponential backoff retries. The approach is sound: it distinguishes navigation from tab close, cleans up old session state, notifies the relay, and retries with proper guards against races (concurrent re-attach, user toggle, relay disconnect, tab removal). - **Key issue found:** The `reason` parameter from `chrome.debugger.onDetach` is not checked for `canceled_by_user` or `replaced_with_devtools`, which means the extension will fight the user's explicit action to dismiss the debugger bar by re-attaching 3 times before giving up. - Race condition handling between `onRemoved` and `onDebuggerDetach` is correctly implemented. - The new `chrome.tabs.onRemoved` listener properly cleans up stale state. <h3>Confidence Score: 3/5</h3> - Generally safe to merge but has a notable UX bug where the extension will fight user-initiated debugger dismissal - The core SPA navigation re-attach logic is well-structured with proper race condition handling, but the missing check for `canceled_by_user` and `replaced_with_devtools` detach reasons is a real UX issue that will frustrate users who manually dismiss the debugger bar. - `assets/chrome-extension/background.js` — the `onDebuggerDetach` function needs to check the `reason` parameter before attempting re-attach _{Last reviewed commit: 0643000} <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->