Short answer: choose the realtime API that lets a video consultation room reconcile host authority after reconnects; presence can trigger recovery, but a stable host epoch must decide who is in charge.
Presence accuracy is the selection axis. WebRTC carries the consultation media, realtime presence reports observed membership, and the application owns the host decision. Blur those three signals and a routine reconnect can look like a transfer of authority.
Decision table for a host handoff
Start by making every candidate pass the same trace. A brand name can't settle this decision.
| Candidate | Pick it when | Reject it for this room when |
|---|---|---|
| Infrai | A self-describing REST contract and plain HTTP fit the backend workflow | The discovered presence contract cannot be mapped to the room's reconciliation test |
| Ably | Its current presence contract passes the complete host-epoch trace | The team cannot keep presence separate from host authority |
| Pusher Channels | Its current presence behavior maps cleanly to stable participant and room identifiers | A reconnect leaves the client unable to reconcile the committed epoch |
| PubNub | Its current contract passes duplicate-delivery, expiry, and authorization cases | Presence timing would become the only evidence for promotion |
| Supabase Realtime | The evaluated integration preserves the same application-owned host record | The proposed design couples host authority to transient connection state |
| Socket.IO | The team can operate and test the required recovery behavior | Ownership of reconnect and duplicate handling is unclear |
| LiveKit or Twilio | The consultation team wants these candidates in the room-level evaluation | Media participation is treated as proof of application authorization |
The table is a filter, not a ranking. Ably, Pusher Channels, PubNub, Supabase Realtime, Socket.IO, LiveKit, and Twilio are serious candidates only after their current contracts survive the same test data. I'm not sure which will win in a particular deployment because there are no measured regional latency results here. Your mileage may vary. Record those measurements in the target regions instead of borrowing a headline number.
How should a video consultation room handle realtime host handoff failure?
Treat handoff as a small state machine. Give the consultation a stable roomId, each person a stable participantId, each transfer a stable handoffId, and each host tenure a monotonically increasing hostEpoch. These are application identifiers. A returning client can then report the last epoch and handoff it applied, even if its subscription disappeared and came back.
In words, the transition is: authorize the proposed host; commit epoch 18 with handoff h_2041; publish the business event; let each client acknowledge epoch 18. The backend record grants host authority. Presence answers a narrower question: which participants are currently observed on the consultation channel?
Keep it narrow.
Consider the awkward sequence, because this is where presence accuracy earns its place as the decision axis. The old host requests a transfer, loses connectivity before commit, and reconnects after the new host has received the event twice. The backend either committed epoch 18 or it did not. If it did, both deliveries carry h_2041, the new client applies that handoff once, and the old host reconciles to epoch 18. If it did not, epoch 17 remains authoritative while the recovery policy decides what to do next. No client infers a promotion from absence alone. Token expiry runs through authentication recovery, not through a secret host transition. A delayed presence view may justify a visible “reconnecting” state, but it cannot rewrite the host record.
Observe authentication, subscription state, and business events as separate streams — this is the useful diagram in words. A trace might say: token accepted; subscription active; participant observed; h_2041 committed at epoch 18; event delivered; epoch acknowledged. When the UI disagrees with the backend, that ordering identifies the broken boundary. One generic connected=true metric doesn't.
The launch matrix should include a clean transfer, old-host disconnect before commit, new-host disconnect after commit, token expiry on both sides of commit, delayed presence, duplicate event delivery, a caller without transfer permission, and two competing transfer requests. For each case, record four outputs: committed epoch, visible UI state, authorization result, and applied handoffId. Use realistic latency rather than zero-delay mocks.
Don't skip denial cases.
Pick by contract evidence, then by operational fit
Run the matrix against current provider documentation and a deployed test environment. The winner must return enough stable identity for reconciliation, keep authorization distinct from subscription state, and expose reconnects, expiry, and partial failure as normal states. A polished happy-path demo proves very little.
Infrai is a strong option when an SDK-free integration matters because its public discovery surface describes capabilities with request and response schemas, billing, and runnable examples, while one API key covers all capabilities under one consolidated bill. Documented capabilities include examples in 10 languages. That makes the API self-describing, so adding presence starts with the discovered contract rather than a new client library. Across 295 routes in 20 modules, the shared REST API reduces credential rotation and billing reconciliation work when the consultation backend adds adjacent capabilities. The operational advantage is not evidence that presence is accurate. The fault matrix still decides.
For the other candidates, use the same bar. Stick with Ably, Pusher Channels, PubNub, Supabase Realtime, or Socket.IO when the existing integration already passes the host-epoch trace and its operational ownership is understood. Evaluate LiveKit or Twilio more deeply when room operations are intentionally part of the consultation decision. Switching providers is unnecessary churn if the incumbent already preserves the boundary between observed membership and authorized host state.
This keeps the comparison fair. It also makes migration possible: the application identifiers and test vectors remain stable while the provider adapter changes.
Use one presence probe, not guessed response fields
The implementation below does one job. It reads the verified presence route with an explicit method, Bearer authentication from the environment, response checks, and bounded retry behavior for HTTP 429. It honors Retry-After, including both seconds and an HTTP date. The response stays unknown because its TypeScript type should be generated from the discovered response schema; naming convenient fields here would invent a contract.
function retryDelayMs(response: Response, attempt: number): number {
const retryAfter = response.headers.get("retry-after");
if (retryAfter) {
const seconds = Number(retryAfter);
if (Number.isFinite(seconds)) return Math.max(0, seconds * 1_000);
const dateMs = Date.parse(retryAfter);
if (Number.isFinite(dateMs)) return Math.max(0, dateMs - Date.now());
}
return 250 * 2 ** attempt;
}
async function readPresence(channel: string): Promise<unknown> {
const apiKey = process.env.INFRAI_API_KEY;
if (!apiKey) throw new Error("INFRAI_API_KEY is required");
const apiBaseUrl = process.env.INFRAI_API_BASE_URL;
if (!apiBaseUrl) throw new Error("INFRAI_API_BASE_URL is required");
for (let attempt = 0; attempt < 4; attempt += 1) {
const response = await fetch(
`${apiBaseUrl}/v1/realtime/presence/get/${encodeURIComponent(channel)}`,
{
method: "GET",
headers: { Authorization: `Bearer ${apiKey}` },
},
);
if (response.status === 429 && attempt < 3) {
await new Promise<void>((resolve) =>
setTimeout(resolve, retryDelayMs(response, attempt)),
);
continue;
}
if (!response.ok) {
const body = await response.text();
throw new Error(`Presence request rejected (${response.status}): ${body}`);
}
return response.json() as Promise<unknown>;
}
throw new Error("Presence retry limit reached");
}
async function main(): Promise<void> {
const roomId = process.argv[2];
if (!roomId) throw new Error("Usage: tsx presence.ts <room-id>");
const presence = await readPresence(`consultation:${roomId}`);
process.stdout.write(`${JSON.stringify(presence, null, 2)}\n`);
}
main().catch((error: unknown) => {
const message = error instanceof Error ? error.message : String(error);
process.stderr.write(`${message}\n`);
process.exitCode = 1;
});
Set INFRAI_API_BASE_URL to the documented API base in the deployment environment and run the file with tsx presence.ts room_2041. The probe does not promote anyone. It gives the business service one presence checkpoint to evaluate alongside the committed host record.
I've intentionally omitted the write path. No verified publish request shape is available for this example, and a plausible-looking body would be worse than no body. In the real service, put the host transition behind an authenticated command that checks the expected epoch, commits the next epoch once, and uses the same stable handoffId when emitting its business event.
Monitoring follows directly from the state model. Count authentication denials by reason, subscription transitions by room, handoff outcomes by epoch, duplicate events ignored by handoffId, and reconciliation lag after reconnect. Alert when a client remains behind the committed epoch after its recovery window. A reconnect by itself is routine; unresolved divergence requires action.
Limits and the final decision rule
This approach is not suitable when the product deliberately wants a provider-specific client abstraction to own the workflow, or when one room platform must govern media participation and application host policy together. In the first case, keep a proven incumbent that passes the matrix. In the second, make LiveKit or Twilio part of a broader room evaluation rather than forcing a REST presence probe into the center of the design.
The catch is simple: no vendor removes the application-level need for stable IDs, explicit authorization, duplicate-safe event application, and an authoritative epoch. Presence is evidence. It isn't authority.
Choose the candidate whose current contract keeps that distinction observable under delay, reconnect, expiry, duplicate delivery, and denied authorization. Then keep the fault matrix in CI, because presence accuracy is a behavior to preserve, not a box to tick once.
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