refactor(msteams): extract implicit mention logic into testable utility

vongohren · claude · vongohren · commit 847590bcafdd · 2026-03-09T15:30:06.000+01:00
Extract the implicit mention computation from message-handler.ts into a
dedicated implicit-mention.ts module. Both the production code and the
tests now import the same function, so regressions in the logic will be
caught by the test suite.

Addresses review feedback about test helper duplicating production logic.

Co-Authored-By: Claude Opus 4.6 (1M context) &lt;noreply@anthropic.com&gt;
diff --git a/extensions/msteams/src/monitor-handler/implicit-mention.ts b/extensions/msteams/src/monitor-handler/implicit-mention.ts
@@ -0,0 +1,27 @@
+import { extractMSTeamsConversationMessageId, normalizeMSTeamsConversationId } from "../inbound.js";
+import { wasMSTeamsMessageSent } from "../sent-message-cache.js";
+
+/**
+ * Determines whether an inbound Teams activity is an implicit mention —
+ * i.e. a thread reply to a message the bot previously sent.
+ *
+ * Two lookup paths:
+ *  1. `replyToId` directly references a bot-sent message.
+ *  2. `conversation.id` contains `;messageid=<threadRootId>` pointing to a
+ *     bot-sent (or bot-cached) thread root. This covers the case where Teams
+ *     omits `replyToId` on thread replies.
+ */
+export function computeImplicitMention(activity: {
+  conversation?: { id?: string };
+  replyToId?: string;
+}): boolean {
+  const rawConversationId = activity.conversation?.id ?? "";
+  const conversationId = normalizeMSTeamsConversationId(rawConversationId);
+  const replyToId = activity.replyToId ?? undefined;
+  const threadRootId = extractMSTeamsConversationMessageId(rawConversationId);
+  return Boolean(
+    conversationId &&
+    ((replyToId && wasMSTeamsMessageSent(conversationId, replyToId)) ||
+      (threadRootId && wasMSTeamsMessageSent(conversationId, threadRootId))),
+  );
+}
diff --git a/extensions/msteams/src/monitor-handler/message-handler.implicit-mention.test.ts b/extensions/msteams/src/monitor-handler/message-handler.implicit-mention.test.ts
@@ -1,43 +1,6 @@
 import { describe, expect, it, beforeEach } from "vitest";
-import { extractMSTeamsConversationMessageId, normalizeMSTeamsConversationId } from "../inbound.js";
-import {
-  clearMSTeamsSentMessageCache,
-  recordMSTeamsSentMessage,
-  wasMSTeamsMessageSent,
-} from "../sent-message-cache.js";
-
-/**
- * Tests for the implicit mention detection logic as implemented in
- * message-handler.ts lines 678-687. We test the computation directly
- * rather than through the full handler to avoid needing the full
- * PluginRuntime/routing setup.
- *
- * The logic under test:
- *   const rawConversationId = activity.conversation?.id ?? "";
- *   const conversationId = normalizeMSTeamsConversationId(rawConversationId);
- *   const replyToId = activity.replyToId ?? undefined;
- *   const threadRootId = extractMSTeamsConversationMessageId(rawConversationId);
- *   const implicitMention = Boolean(
- *     conversationId && (
- *       (replyToId && wasMSTeamsMessageSent(conversationId, replyToId)) ||
- *       (threadRootId && wasMSTeamsMessageSent(conversationId, threadRootId))
- *     ),
- *   );
- */
-function computeImplicitMention(activity: {
-  conversation?: { id?: string };
-  replyToId?: string;
-}): boolean {
-  const rawConversationId = activity.conversation?.id ?? "";
-  const conversationId = normalizeMSTeamsConversationId(rawConversationId);
-  const replyToId = activity.replyToId ?? undefined;
-  const threadRootId = extractMSTeamsConversationMessageId(rawConversationId);
-  return Boolean(
-    conversationId &&
-    ((replyToId && wasMSTeamsMessageSent(conversationId, replyToId)) ||
-      (threadRootId && wasMSTeamsMessageSent(conversationId, threadRootId))),
-  );
-}
+import { clearMSTeamsSentMessageCache, recordMSTeamsSentMessage } from "../sent-message-cache.js";
+import { computeImplicitMention } from "./implicit-mention.js";
 
 describe("implicit mention detection (conversation.id threadRootId fallback)", () => {
   const CONV_ID = "19:group@thread.tacv2";
diff --git a/extensions/msteams/src/monitor-handler/message-handler.ts b/extensions/msteams/src/monitor-handler/message-handler.ts
@@ -46,7 +46,8 @@ import { extractMSTeamsPollVote } from "../polls.js";
 import { createMSTeamsReplyDispatcher } from "../reply-dispatcher.js";
 import { getMSTeamsRuntime } from "../runtime.js";
 import type { MSTeamsTurnContext } from "../sdk-types.js";
-import { recordMSTeamsSentMessage, wasMSTeamsMessageSent } from "../sent-message-cache.js";
+import { recordMSTeamsSentMessage } from "../sent-message-cache.js";
+import { computeImplicitMention } from "./implicit-mention.js";
 import { resolveMSTeamsInboundMedia } from "./inbound-media.js";
 
 export function createMSTeamsMessageHandler(deps: MSTeamsMessageHandlerDeps) {
@@ -687,13 +688,7 @@ export function createMSTeamsMessageHandler(deps: MSTeamsMessageHandlerDeps) {
     const wasMentioned = wasMSTeamsBotMentioned(activity);
     const rawConversationId = activity.conversation?.id ?? "";
     const conversationId = normalizeMSTeamsConversationId(rawConversationId);
-    const replyToId = activity.replyToId ?? undefined;
-    const threadRootId = extractMSTeamsConversationMessageId(rawConversationId);
-    const implicitMention = Boolean(
-      conversationId &&
-      ((replyToId && wasMSTeamsMessageSent(conversationId, replyToId)) ||
-        (threadRootId && wasMSTeamsMessageSent(conversationId, threadRootId))),
-    );
+    const implicitMention = computeImplicitMention(activity);
 
     await inboundDebouncer.enqueue({
       context,
