Tabloom

A Chrome extension that records the active tab's audio, lets users trim and remove silent sections, and download it as MP3.

Run it

1. Install dependencies with npm install.
2. Run npm run build; the loadable extension is created in dist/.
3. In Chrome, open chrome://extensions, enable Developer mode, select Load unpacked, and choose dist/.
4. Pin the extension, open it on an audible tab, and choose Start recording. There is no sharing picker: audio only is captured from the tab that was active when the action was invoked.
5. You can close the popup while recording. Reopen it to pause, resume, finish, or cancel. Finished recordings are kept locally in IndexedDB until the next recording replaces them.

Agent Notes 🤖

• No runtime WebExtension polyfill is used. The project uses Chrome's native chrome.* global and @types/chrome. Safari and Firefox provide a native browser.* global, but Chrome does not; therefore there is no native browser replacement that works unchanged in all three browsers.
• Direct capture is intentionally implemented with chrome.tabCapture.getMediaStreamId() and audio-only getUserMedia() constraints. Chrome requires the tabCapture permission and a user invocation, but does not show a source picker. The extension reconnects the capture stream to the audio destination so playback continues during recording.
• The recording runs in an MV3 offscreen document, not the popup. The service worker obtains a tabCapture stream ID and the offscreen document owns MediaRecorder, so popup lifecycle no longer affects capture.
• MP3 export uses @breezystack/lamejs, the maintained ESM/type-enabled fork. It replaces the legacy lamejs package, which has the known bundler error MPEGMode is not defined.
• Safari WebExtensions do not expose this Chrome-specific tabCapture feature, so the exact no-picker, automatically-selected-tab requirement cannot be fulfilled in Safari with WebExtension APIs alone. The UI reports this limitation instead of falling back to screen sharing. A Safari version would require an approved native macOS companion using Apple capture APIs, which is a separate product architecture.
• The source recording is decoded with Web Audio, so trimming and silence deletion operate on PCM audio. Export uses LAME at a configurable bitrate up to 320 kbps, the MP3 maximum.
• Recordings stay in memory and are not uploaded or persisted. Keep the popup open while recording; closing it ends the extension page and may end the session.

Verification checklist

1. Start a recording on an audible tab and confirm the toolbar badge says REC.
2. Pause and resume; the timer should exclude the paused interval.
3. Finish, verify the preview plays, and trim the range.
4. Use Delete silent parts on a recording with a known pause, then export and inspect the MP3 bitrate.