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zebra-spaces: rebuild SFU sub PC on connectionstatechange + visibility resume

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Lid-close / suspend recovery. When the OS suspends the browser, the
SFU sub PC goes 'disconnected' → 'failed' (or just stops carrying RTP
silently). On resume the old PC is dead but JS still holds a reference
to it, so we get frozen remote screens until the host hard-reboots.

Two recovery paths added:

1. pc.onconnectionstatechange — on 'failed' or 'closed' for the active
   sub PC, sfuUnsubscribe() then sfuSubscribe() to rebuild. The
   wantConnected guard prevents fighting a deliberate leave.

2. document visibilitychange → 'visible' — Chromium on Linux can
   silently keep the PC in 'connected' state through a suspend cycle
   without firing connectionstatechange. So we also probe on tab/lid
   wake: if the sub PC's connectionState is anything other than
   'connected'/'new'/'connecting', force the rebuild.

Both paths converge on the same teardown + re-subscribe so the SFU
sends a fresh initial SDP with every current publisher's tracks.

83 FSM tests still green; this is runtime-only and doesn't affect
the pure state machines yet.
This commit is contained in:
Russell Ballestrini 2026-06-02 11:25:41 -04:00
parent a2dda2d586
commit 6a72e77518
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1 changed files with 38 additions and 2 deletions
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40
web/zebra-spaces.html
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@ -1996,6 +1996,23 @@ async function sfuSubscribe(){
});
if (!ackRes.ok){ pc.close(); throw new Error('sfu subscribe-answer http '+ackRes.status); }
sfuSubPC = pc; sfuSubPeerID = offer.peer_id;
/* survive laptop-lid-close / network suspend. When the OS suspends the
* browser the SFU sub PC goes 'disconnected' first (transient) then
* 'failed'. On 'failed' the existing PC is dead — RTP can never
* recover even if we resume — so we tear it down and rebuild via
* sfuUnsubscribe + sfuSubscribe. The auto-rejoin code that follows
* a hard refresh handles the WS side; this handles the SFU side. */
pc.onconnectionstatechange = () => {
const s = pc.connectionState;
if (s === 'failed' || s === 'closed'){
logLine('err', 'sfu sub PC ' + s + ' — rebuilding');
if (sfuSubPC === pc){
sfuUnsubscribe().then(() => {
if (wantConnected && roomID) sfuSubscribe().catch(e => logLine('err','sfu re-subscribe: '+e.message));
});
}
}
};
/* SSE: server pushes renegotiation offers when publisher set changes.
* We answer each via POST /answer. ping events are keepalive only.
*
@ -3128,6 +3145,25 @@ if (navigator.mediaDevices && navigator.mediaDevices.addEventListener){
* sees how many inputs exist. */
refreshMicList();
/* laptop-lid-close / sleep / suspend recovery: when the tab comes back
* to visible, check whether our SFU sub PC is still in a healthy state.
* Some browsers (Chromium on Linux specifically) don't fire
* connectionstatechange on suspend → resume — the PC sits silently in
* 'connected' but no RTP flows. If it's in any non-live state, force
* the rebuild. */
document.addEventListener('visibilitychange', () => {
if (document.visibilityState !== 'visible') return;
if (!wantConnected || !sfuSubPC) return;
const s = sfuSubPC.connectionState;
if (s === 'failed' || s === 'closed' || s === 'disconnected'){
logLine('err', 'visibility back, sub PC ' + s + ' — rebuilding');
const pc = sfuSubPC;
sfuUnsubscribe().then(() => {
if (wantConnected && roomID) sfuSubscribe().catch(e => logLine('err','sfu re-subscribe: '+e.message));
});
}
});
/* ==================================================================
* leave / entry buttons
* ================================================================== */
@ -3226,8 +3262,8 @@ logLine('', 'ready — pick a handle, type a rendezvous code, enter the space');
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