feat(streams): add phase-1 single-server SFU session and transport APIs

Backend/media/sfu/noop.ts

@@ -1,6 +1,7 @@
 import { randomUUID } from 'crypto';
 
 import { mediaConfig } from '../config';
+import { SfuSessionRegistry } from './registry';
 import type {
   SfuPublishTransportRequest,
   SfuPublishTransportResult,
@@ -25,11 +26,11 @@ const toIceServers = (): Array<{ urls: string; username?: string; credential?: s
 
 export class NoopSfuService implements SfuService {
   mode: 'single_server_sfu' = 'single_server_sfu';
-  private readonly sessions = new Map<string, SfuSessionDescriptor>();
+  private readonly registry = new SfuSessionRegistry();
 
   async startSession(input: SfuSessionStartInput): Promise<SfuSessionDescriptor> {
     const now = new Date().toISOString();
-    const existing = this.sessions.get(input.streamSessionId);
+    const existing = this.registry.get(input.streamSessionId);
     if (existing) return existing;
 
     const descriptor: SfuSessionDescriptor = {
@@ -40,18 +41,24 @@ export class NoopSfuService implements SfuService {
       state: 'starting',
       createdAt: now,
     };
-    this.sessions.set(input.streamSessionId, descriptor);
-    return descriptor;
+    return this.registry.set(descriptor);
+  }
+
+  async setSessionState(streamSessionId: string, state: SfuSessionDescriptor['state']): Promise<void> {
+    this.registry.updateState(streamSessionId, state);
   }
 
   async endSession(streamSessionId: string): Promise<void> {
-    const existing = this.sessions.get(streamSessionId);
-    if (!existing) return;
-    this.sessions.set(streamSessionId, { ...existing, state: 'ended' });
+    this.registry.updateState(streamSessionId, 'ending');
+    this.registry.updateState(streamSessionId, 'ended');
   }
 
   async getSession(streamSessionId: string): Promise<SfuSessionDescriptor | null> {
-    return this.sessions.get(streamSessionId) ?? null;
+    return this.registry.get(streamSessionId);
+  }
+
+  async listSessions(): Promise<SfuSessionDescriptor[]> {
+    return this.registry.list();
   }
 
   async createPublishTransport(_input: SfuPublishTransportRequest): Promise<SfuPublishTransportResult> {
@@ -68,4 +75,3 @@ export class NoopSfuService implements SfuService {
     };
   }
 }
-