feat: add private office media signaling

server/src/media/bindings.ts

@@ -0,0 +1,41 @@
+/** Server-authoritative lookup for authored office screen surfaces. */
+
+import { Plan } from "../../../src/interiors/plan.ts";
+import type { Office } from "../../../src/interiors/types.ts";
+import FRONTIER_VALLEY from "../../../src/offices/frontier-valley.ts";
+import LUMBRIDGE_HQ from "../../../src/offices/lumbridge-hq.ts";
+import MATEO_COURT from "../../../src/offices/mateo-court.ts";
+import type { ScreenShareBinding } from "../../../src/media/signalingTypes.ts";
+
+const SCREEN_KINDS = new Set([
+  "tera:screen.monitor",
+  "tera:screen.wall-display",
+]);
+
+const BUNDLED_OFFICES: ReadonlyMap<string, Office> = new Map(
+  [LUMBRIDGE_HQ, FRONTIER_VALLEY, MATEO_COURT].map((office) => [office.id, office]),
+);
+
+/**
+ * A bundled pack is public sample geometry, so its exact authored screen
+ * catalogue is the only bundled exception. No real/private pack is inferred.
+ */
+export function bundledMediaOffice(officeId: string): Office | null {
+  return BUNDLED_OFFICES.get(officeId) ?? null;
+}
+
+/**
+ * Confirm an exact client binding against a validated/resolved office pack.
+ * Room membership is computed from the prop's authored position rather than
+ * trusting a caller-provided label.
+ */
+export function officeHasMediaBinding(office: Office, binding: ScreenShareBinding): boolean {
+  if (office.id !== binding.officeId) return false;
+  const plan = new Plan(office, { depth: "full", warn: false });
+  const level = plan.level(binding.levelId);
+  if (!level) return false;
+  const prop = level.props.find((candidate) => candidate.id === binding.screenId);
+  if (!prop || !SCREEN_KINDS.has(prop.kind)) return false;
+  const roomId = plan.roomAt(level.id, prop.position)?.id ?? null;
+  return roomId === binding.roomId;
+}