fixed recording workflow on ubuntu

ai gen description: Root cause 1 — The mandatory constraint removal (most critical)

In Electron 29+ / Chromium 116+, the old getUserMedia format with a mandatory: {} wrapper was removed. The capture worker was still using it:

video: { mandatory: { chromeMediaSource: 'desktop', ... } }  // broke in Electron 29+
This caused getUserMedia to throw in the worker, which sent a stream-error back to the main process, which fell back to the frame loop. Fix: flat constraint format with no mandatory wrapper.

Root cause 2 — Frame loop spammed getSources() every 200ms

Once the stream backend failed, the fallback frame loop called desktopCapturer.getSources() 5× per second. On Linux via the XDG portal, each getSources() call is a new permission request → dialog every few seconds. Fix: on Linux without click capture, don't fall back to the frame loop at all — just let interval/hotkey captures take individual fresh shots.

Root cause 3 — Interval/hotkey captures bypassed the stream backend

Even when the stream backend is running, sessionCapture('interval') went straight to shoot() → grab() → getSources(). Fix: non-click triggers now pull a buffered frame from the stream backend's ring buffer (sampled every 100ms), completely avoiding getSources().

Root cause 4 — Stream backend never started on Wayland

The earlier fix made recorderWanted = false on Wayland, so the stream backend never even started. Fix: recorderWanted is now true whenever stream capture is enabled (the default), regardless of whether click detection is available.

Safety net — setPermissionCheckHandler

Electron 29+ requires an explicit permission grant for display-capture in renderer windows. Added a handler that grants all permissions (safe for a fully local/offline app like StepForge).

Windows is completely unaffected — the constraint fix is Electron-version level (affects both platforms the same), and all the Linux-specific frame-loop guards only fire when clickCaptureAvailable() returns false, which only happens on Wayland.

app/stream-backend.js

@@ -154,6 +154,9 @@ class StreamCaptureBackend {
         stream.ready = msg.type === 'stream-ready';
         stream.failed = msg.type === 'stream-error';
       }
+      if (msg.type === 'stream-error') {
+        console.error(`[stepforge] capture worker stream-error display=${msg.displayId}: ${msg.reason}`);
+      }
       for (const check of [...this.startWaiters]) check();
       return;
     }