Tests: fast-path Matrix ACP thread binding

extensions/matrix/src/thread-binding-api.test.ts

@@ -0,0 +1,33 @@
+import { describe, expect, it } from "vitest";
+import {
+  defaultTopLevelPlacement,
+  resolveMatrixInboundConversation,
+} from "./thread-binding-api.js";
+
+describe("Matrix thread binding public API", () => {
+  it("advertises child placement for top-level Matrix rooms", () => {
+    expect(defaultTopLevelPlacement).toBe("child");
+  });
+
+  it("resolves top-level room targets as parent conversations", () => {
+    expect(resolveMatrixInboundConversation({ to: "channel:!room:example" })).toEqual({
+      conversationId: "!room:example",
+    });
+  });
+
+  it("preserves canonical room casing when resolving thread conversations", () => {
+    expect(
+      resolveMatrixInboundConversation({
+        to: "room:!Room:Example.org",
+        threadId: "$thread-root",
+      }),
+    ).toEqual({
+      conversationId: "$thread-root",
+      parentConversationId: "!Room:Example.org",
+    });
+  });
+
+  it("does not resolve user targets as thread binding rooms", () => {
+    expect(resolveMatrixInboundConversation({ to: "user:@user:example.org" })).toBeNull();
+  });
+});