refactor(vibe): simplify durable session flow

backend/src/services/vibe-session-coordinator.service.ts

@@ -1,12 +1,6 @@
 import { DbService, VibeEvent, VibePlan, VibeSession } from './db.service.js';
 import { SessionDirector } from './session-director.service.js';
 import { Candidate } from './generators.service.js';
-import {
-  initialVibeState,
-  normalizeVibeContext,
-  normalizeVibeEventPayload,
-  VibeContext,
-} from './vibe-context.service.js';
 
 /**
  * This is deliberately a narrow bridge between the durable Vibe ledger and
@@ -16,7 +10,7 @@ import {
 export const DEFAULT_VIBE_POLICY_VERSION = 'vibe-v2-initial';
 
 export const VIBE_EVENT_TYPES = [
-  'session_started', 'session_resumed', 'session_ended', 'context_changed',
+  'session_started', 'session_resumed', 'session_ended',
   'plan_published', 'track_served', 'playback_started', 'progress', 'completed',
   'skipped', 'disliked', 'kept', 'favourite_added', 'queue_removed',
   'manual_search', 'album_opened', 'artist_opened', 'playlist_added',
@@ -27,9 +21,6 @@ export type VibeEventType = (typeof VIBE_EVENT_TYPES)[number];
 
 export interface StartVibeSessionInput {
   seedTrackId?: string;
-  context?: VibeContext | Record<string, unknown>;
-  intent?: string;
-  policyVersion?: string;
   resumeSessionId?: string;
 }
 
@@ -79,14 +70,19 @@ export class VibeSessionCoordinator {
 
   async start(userId: string, input: StartVibeSessionInput): Promise<VibeSessionResponse> {
     if (input.resumeSessionId) return this.resume(userId, input.resumeSessionId);
-    const context = normalizeVibeContext({ ...(input.context ?? {}) });
-    const initialState = initialVibeState(context);
-    const policyVersion = input.policyVersion ?? DEFAULT_VIBE_POLICY_VERSION;
+    // Vibe has no reliable device/activity/location signal. Start from neutral
+    // recommendation state and let actual listening behaviour shape the plan.
+    const initialState = {
+      energy: 0.5,
+      noveltyHunger: 0.3,
+      explorationCoefficient: 0.3,
+      discoveryRadius: 0.38,
+      sessionGoal: { type: 'discovery' as const, target: 1, progress: 0 },
+    };
     const session = await this.db.createVibeSession({
       userId,
-      policyVersion,
+      policyVersion: DEFAULT_VIBE_POLICY_VERSION,
       seedTrackId: input.seedTrackId ?? null,
-      context: { ...context },
       profile: {
         goals: initialState.sessionGoal,
         explorationCoefficient: initialState.explorationCoefficient,
@@ -99,14 +95,13 @@ export class VibeSessionCoordinator {
     // session while the durable tables remain the source of truth.
     await this.db.createSessionState(
       userId,
-      initialState.contextLabel ?? input.intent,
+      undefined,
       {
         energy: initialState.energy,
         noveltyHunger: initialState.noveltyHunger,
         explorationCoefficient: initialState.explorationCoefficient,
         discoveryRadius: initialState.discoveryRadius,
         sessionGoal: initialState.sessionGoal,
-        context,
       },
       session.id,
     );
@@ -114,7 +109,7 @@ export class VibeSessionCoordinator {
       sessionId: session.id,
       userId,
       type: 'session_started',
-      payload: { policyVersion, context, intent: input.intent ?? null },
+      payload: { policyVersion: DEFAULT_VIBE_POLICY_VERSION },
     });
 
     const candidates = await this.director.buildPlan(userId, session.id, input.seedTrackId);
@@ -128,8 +123,7 @@ export class VibeSessionCoordinator {
         reason: 'session_started',
         stateSnapshot: state,
         objectiveSnapshot: {
-          policyVersion,
-          intent: input.intent ?? null,
+          policyVersion: DEFAULT_VIBE_POLICY_VERSION,
           horizonTracks: candidates.length,
           ...(candidates[0]?.plan?.objective ?? {}),
         },
@@ -203,7 +197,6 @@ export class VibeSessionCoordinator {
       // events are immutable. The DB repeats this boundary for non-HTTP
       // callers; keeping it here also makes coordinator callers see exactly
       // what will be persisted.
-      const payload = normalizeVibeEventPayload(input.type, input.payload);
       const result = await this.db.recordVibeEvent({
         sessionId,
         userId,
@@ -213,7 +206,7 @@ export class VibeSessionCoordinator {
         occurredAt: input.occurredAt,
         positionMs: input.positionMs,
         durationMs: input.durationMs,
-        payload,
+        payload: input.payload,
       });
       // The ledger write is authoritative; this idempotent projection updates
       // exploration only after the exact event exists. Keep the compatibility