refactor: share thread binding id parser

src/channels/thread-binding-id.test.ts

@@ -0,0 +1,43 @@
+import { describe, expect, it } from "vitest";
+import { resolveThreadBindingConversationIdFromBindingId } from "./thread-binding-id.js";
+
+describe("resolveThreadBindingConversationIdFromBindingId", () => {
+  it("returns the conversation id for matching account-prefixed binding ids", () => {
+    expect(
+      resolveThreadBindingConversationIdFromBindingId({
+        accountId: "default",
+        bindingId: "default:thread-123",
+      }),
+    ).toBe("thread-123");
+  });
+
+  it("returns undefined when binding id is missing or account prefix does not match", () => {
+    expect(
+      resolveThreadBindingConversationIdFromBindingId({
+        accountId: "default",
+        bindingId: undefined,
+      }),
+    ).toBeUndefined();
+    expect(
+      resolveThreadBindingConversationIdFromBindingId({
+        accountId: "default",
+        bindingId: "work:thread-123",
+      }),
+    ).toBeUndefined();
+  });
+
+  it("trims whitespace and rejects empty ids after the account prefix", () => {
+    expect(
+      resolveThreadBindingConversationIdFromBindingId({
+        accountId: "default",
+        bindingId: "  default:group-1:topic:99  ",
+      }),
+    ).toBe("group-1:topic:99");
+    expect(
+      resolveThreadBindingConversationIdFromBindingId({
+        accountId: "default",
+        bindingId: "default:   ",
+      }),
+    ).toBeUndefined();
+  });
+});

src/channels/thread-binding-id.ts

@@ -0,0 +1,15 @@
+export function resolveThreadBindingConversationIdFromBindingId(params: {
+  accountId: string;
+  bindingId?: string;
+}): string | undefined {
+  const bindingId = params.bindingId?.trim();
+  if (!bindingId) {
+    return undefined;
+  }
+  const prefix = `${params.accountId}:`;
+  if (!bindingId.startsWith(prefix)) {
+    return undefined;
+  }
+  const conversationId = bindingId.slice(prefix.length).trim();
+  return conversationId || undefined;
+}