diff --git a/codebase/@features/broadcast/controller/broadcast-controller.ts b/codebase/@features/broadcast/controller/broadcast-controller.ts
index b91dbdac..c989b995 100644
--- a/codebase/@features/broadcast/controller/broadcast-controller.ts
+++ b/codebase/@features/broadcast/controller/broadcast-controller.ts
@@ -13,15 +13,15 @@
  * consistent state after every mutation.
  */
 
-import type { Destination, RelayStatus, ObsScene } from "../shared/types";
+import type { Destination, RelayStatus, ObsScene, IDestinationStore } from "../shared/types";
 import { ObsClient, ObsError } from "./obs-client";
 import { FanoutManager } from "./fanout-manager";
-import { DestinationStore } from "./destination-store";
 
 export interface BroadcastControllerOptions {
   obs: ObsClient;
   fanout: FanoutManager;
-  store: DestinationStore;
+  /** Any IDestinationStore impl (file-backed in controller, Postgres in backend-api). */
+  store: IDestinationStore;
 }
 
 export class BroadcastController {
@@ -35,7 +35,7 @@ export class BroadcastController {
     return this.opts.fanout;
   }
 
-  get store(): DestinationStore {
+  get store(): IDestinationStore {
     return this.opts.store;
   }
 
diff --git a/codebase/@features/broadcast/controller/destination-store.ts b/codebase/@features/broadcast/controller/destination-store.ts
index 8ca04e43..a2a710ec 100644
--- a/codebase/@features/broadcast/controller/destination-store.ts
+++ b/codebase/@features/broadcast/controller/destination-store.ts
@@ -10,11 +10,11 @@
  * - All mutations await save.
  */
 
-import type { Destination } from "../shared/types";
+import type { Destination, IDestinationStore } from "../shared/types";
 
 const DEFAULT_FILE = "/data/destinations.json";
 
-export class DestinationStore {
+export class DestinationStore implements IDestinationStore {
   private destinations: Destination[] = [];
   private filePath: string;
   private readonly intendedFilePath: string;
diff --git a/codebase/@features/broadcast/shared/types.ts b/codebase/@features/broadcast/shared/types.ts
index ebcef73e..677321a8 100644
--- a/codebase/@features/broadcast/shared/types.ts
+++ b/codebase/@features/broadcast/shared/types.ts
@@ -15,6 +15,43 @@ export interface Destination {
   url: string;
 }
 
+/**
+ * Default tenant id for the Quinn-first phase. Every persisted row carries a
+ * tenant_id so flipping to multi-performer later is a data activation, not a
+ * schema rewrite. Until SSO/`my` performer identity is wired as the tenant key,
+ * all broadcast rows belong to this seeded tenant.
+ */
+export const DEFAULT_TENANT_ID = 1;
+
+/**
+ * Persistence contract for RTMP destinations.
+ *
+ * Two implementations satisfy this (DIP — BroadcastController depends only on
+ * the interface, never the concrete class):
+ *   - file-backed `DestinationStore`  (controller/, zero-dep, bare-droplet path)
+ *   - `PgDestinationStore`            (backend-api/, Postgres, always-on control plane)
+ *
+ * `list()`/`find()` are synchronous: both impls keep an authoritative in-memory
+ * snapshot, hydrated by `load()` and kept in sync on every mutation.
+ */
+export interface IDestinationStore {
+  /** Hydrate in-memory state. `initialFromEnv` seeds when the backing store is empty. */
+  load(initialFromEnv?: Destination[]): Promise<void>;
+  /** Snapshot copy (safe to mutate by caller). */
+  list(): Destination[];
+  find(name: string): Destination | undefined;
+  /** Idempotent upsert by name. Returns the new full list. */
+  add(dest: Destination): Promise<Destination[]>;
+  /** Remove by name (no-op if absent). Returns the new full list. */
+  remove(name: string): Promise<Destination[]>;
+  /** Replace the whole set. Returns the new full list. */
+  replaceAll(newList: Destination[]): Promise<Destination[]>;
+  /** Diagnostic: where state persists (file path, "postgres", or "" for memory-only). */
+  readonly path: string;
+  /** True when persistence degraded to a fallback/memory-only location. */
+  readonly isUsingFallback: boolean;
+}
+
 export interface FanoutStatus {
   name: string;
   url: string; // may be redacted in some contexts