refactor: isolate playback and upload use cases

packages/core/src/wave.ts

@@ -0,0 +1,62 @@
+/** Policy shared by web and native players; queue ownership stays with the adapter. */
+export const EARLY_SKIP_MS = 30_000;
+export const WAVE_REFILL_AT = 2;
+export type WaveOutcome = 'complete' | 'skip' | 'skip_early' | 'like' | 'dislike';
+export interface WaveInfo {
+  sessionId: string;
+  activity: string | null;
+  mood: string | null;
+  fallback: boolean;
+}
+export interface WaveFeedback { track_id: string; outcome: WaveOutcome }
+export interface WaveGateway<T> {
+  next(sessionId: string, feedback: WaveFeedback[]): Promise<T>;
+}
+
+export class WaveCoordinator<T> {
+  private sessionId: string | null = null;
+  private generation = 0;
+  private pending: WaveFeedback[] = [];
+  private loading: number | null = null;
+
+  constructor(private readonly gateway: WaveGateway<T>) {}
+
+  get version() { return this.generation; }
+  isCurrent(version: number) { return version === this.generation; }
+
+  /** Also invalidates in-flight responses when the context changes within a session. */
+  activate(sessionId: string | null) {
+    this.sessionId = sessionId;
+    this.pending = [];
+    this.loading = null;
+    return ++this.generation;
+  }
+
+  changeContext(sessionId: string) {
+    const pending = this.sessionId === sessionId ? this.pending : [];
+    const version = this.activate(sessionId);
+    this.pending = pending;
+    return version;
+  }
+
+  note(trackId: string, outcome: WaveOutcome) {
+    if (this.sessionId) this.pending.push({ track_id: trackId, outcome });
+  }
+
+  async refill(remaining: number, refresh: boolean, apply: (result: T, current: () => boolean) => void | Promise<void>) {
+    const id = this.sessionId;
+    const version = this.generation;
+    if (!id || this.loading === version || (!refresh && remaining > WAVE_REFILL_AT)) return;
+    this.loading = version;
+    const feedback = this.pending;
+    this.pending = [];
+    try {
+      const result = await this.gateway.next(id, feedback);
+      if (this.isCurrent(version)) await apply(result, () => this.isCurrent(version));
+    } catch {
+      if (this.isCurrent(version)) this.pending = [...feedback, ...this.pending];
+    } finally {
+      if (this.loading === version) this.loading = null;
+    }
+  }
+}