feat(backend): add PUT /api/sources/:sourceId (#87)

Add a PUT endpoint that inserts or fully replaces a user's source
config. Unlike PATCH (which deep-merges and requires an existing row),
PUT requires both `enabled` and `config`, performs an upsert via
INSERT ... ON CONFLICT DO UPDATE, and replaces config entirely.

- Add `upsertConfig` to user-sources data layer
- Add `upsertSourceConfig` to UserSessionManager
- Add `addSource` to UserSession for new source registration
- 12 new tests covering insert, replace, validation, and session refresh

Co-authored-by: Ona <no-reply@ona.com>

apps/aelis-backend/src/session/user-session-manager.ts

@@ -136,6 +136,52 @@ export class UserSessionManager {
 		}
 	}
 
+	/**
+	 * Validates, persists, and upserts a user's source config, then
+	 * refreshes the cached session. Unlike updateSourceConfig, this
+	 * inserts a new row if one doesn't exist and fully replaces config
+	 * (no merge).
+	 *
+	 * @throws {SourceNotFoundError} if the sourceId has no registered provider
+	 * @throws {InvalidSourceConfigError} if config fails schema validation
+	 */
+	async upsertSourceConfig(
+		userId: string,
+		sourceId: string,
+		data: { enabled: boolean; config: unknown },
+	): Promise<void> {
+		const provider = this.providers.get(sourceId)
+		if (!provider) {
+			throw new SourceNotFoundError(sourceId, userId)
+		}
+
+		if (provider.configSchema) {
+			const validated = provider.configSchema(data.config)
+			if (validated instanceof type.errors) {
+				throw new InvalidSourceConfigError(sourceId, validated.summary)
+			}
+		}
+
+		await sources(this.db, userId).upsertConfig(sourceId, {
+			enabled: data.enabled,
+			config: data.config,
+		})
+
+		const session = this.sessions.get(userId)
+		if (session) {
+			if (!data.enabled) {
+				session.removeSource(sourceId)
+			} else {
+				const source = await provider.feedSourceForUser(userId, data.config)
+				if (session.hasSource(sourceId)) {
+					session.replaceSource(sourceId, source)
+				} else {
+					session.addSource(source)
+				}
+			}
+		}
+	}
+
 	/**
 	 * Replaces a provider and updates all active sessions.
 	 * The new provider must have the same sourceId as an existing one.

apps/aelis-backend/src/session/user-session.ts

@@ -73,6 +73,32 @@ export class UserSession {
 		return this.sources.has(sourceId)
 	}
 
+	/**
+	 * Registers a new source in the engine and invalidates all caches.
+	 * Stops and restarts the engine to establish reactive subscriptions.
+	 */
+	addSource(source: FeedSource): void {
+		if (this.sources.has(source.id)) {
+			throw new Error(`Cannot add source "${source.id}": already registered`)
+		}
+
+		const wasStarted = this.engine.isStarted()
+
+		if (wasStarted) {
+			this.engine.stop()
+		}
+
+		this.engine.register(source)
+		this.sources.set(source.id, source)
+
+		this.invalidateEnhancement()
+		this.enhancingPromise = null
+
+		if (wasStarted) {
+			this.engine.start()
+		}
+	}
+
 	/**
 	 * Replaces a source in the engine and invalidates all caches.
 	 * Stops and restarts the engine to re-establish reactive subscriptions.