From 23db233bb5ac910f7a02c4dcb2c015feeeb45ade Mon Sep 17 00:00:00 2001
From: Peter Steinberger <steipete@gmail.com>
Date: Wed, 29 Jul 2026 01:51:48 -0400
Subject: [PATCH] fix(msteams): recognize provider-prefixed target ids
 (#115609)

* fix(msteams): recognize provider-prefixed target ids

* style(msteams): format explicit target regression matrix
---
 extensions/msteams/src/channel.test.ts        | 20 +++++++++++++
 .../msteams/src/resolve-allowlist.test.ts     | 29 +++++++++++++++----
 extensions/msteams/src/resolve-allowlist.ts   |  2 +-
 3 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/extensions/msteams/src/channel.test.ts b/extensions/msteams/src/channel.test.ts
index 284171e15475..12528fc0e6ae 100644
--- a/extensions/msteams/src/channel.test.ts
+++ b/extensions/msteams/src/channel.test.ts
@@ -108,6 +108,26 @@ describe("msteamsPlugin", () => {
     expect(looksLikeId?.("a:1bfPersonalChat")).toBe(true);
     expect(looksLikeId?.("user:Jane Doe")).toBe(false);
   });
+
+  it("recognizes provider-prefixed explicit targets without claiming display names", () => {
+    const messaging = msteamsPlugin.messaging;
+    const aadUserId = "40a1a0ed-4ff2-4164-a219-55518990c197";
+
+    expect(
+      ["teams", "msteams"].map((provider) => {
+        const target = `${provider}:user:${aadUserId}`;
+        return {
+          explicit: messaging?.targetResolver?.looksLikeId?.(target),
+          normalized: messaging?.normalizeTarget?.(target),
+        };
+      }),
+    ).toEqual([
+      { explicit: true, normalized: `user:${aadUserId}` },
+      { explicit: true, normalized: `user:${aadUserId}` },
+    ]);
+    expect(messaging?.targetResolver?.looksLikeId?.("teams:user:Jane Doe")).toBe(false);
+    expect(messaging?.targetResolver?.looksLikeId?.("msteams:user:Jane Doe")).toBe(false);
+  });
 });
 
 describe("msteams config schema", () => {
diff --git a/extensions/msteams/src/resolve-allowlist.test.ts b/extensions/msteams/src/resolve-allowlist.test.ts
index df540b469521..5b3a3cee74a4 100644
--- a/extensions/msteams/src/resolve-allowlist.test.ts
+++ b/extensions/msteams/src/resolve-allowlist.test.ts
@@ -500,12 +500,29 @@ describe("looksLikeMSTeamsTargetId", () => {
     expect(looksLikeMSTeamsTargetId("user:40a1a0ed-4ff2-4164-a219-55518990c197")).toBe(true);
   });
 
-  it.each(["", "   ", "user:John Smith", "Product Team/Roadmap", "Engineering", "hello"])(
-    "rejects non-id inputs (%s)",
-    (raw) => {
-      expect(looksLikeMSTeamsTargetId(raw)).toBe(false);
-    },
-  );
+  it.each([
+    "teams:user:40a1a0ed-4ff2-4164-a219-55518990c197",
+    "msteams:user:40a1a0ed-4ff2-4164-a219-55518990c197",
+    "TEAMS:conversation:19:abc@thread.tacv2",
+    "msteams:19:abc@thread.tacv2",
+    "teams:29:1a2b3c4d5e6f",
+    "  teams:user:40a1a0ed-4ff2-4164-a219-55518990c197  ",
+  ])("accepts provider-prefixed explicit ids (%s)", (raw) => {
+    expect(looksLikeMSTeamsTargetId(raw)).toBe(true);
+  });
+
+  it.each([
+    "",
+    "   ",
+    "user:John Smith",
+    "teams:user:John Smith",
+    "msteams:user:John Smith",
+    "Product Team/Roadmap",
+    "Engineering",
+    "hello",
+  ])("rejects non-id inputs (%s)", (raw) => {
+    expect(looksLikeMSTeamsTargetId(raw)).toBe(false);
+  });
 
   it("normalizes leading/trailing whitespace before classifying", () => {
     expect(looksLikeMSTeamsTargetId("  19:abc@thread.tacv2  ")).toBe(true);
diff --git a/extensions/msteams/src/resolve-allowlist.ts b/extensions/msteams/src/resolve-allowlist.ts
index 309100b1ac80..9e269e14ed63 100644
--- a/extensions/msteams/src/resolve-allowlist.ts
+++ b/extensions/msteams/src/resolve-allowlist.ts
@@ -183,7 +183,7 @@ export function looksLikeMSTeamsConversationId(raw: string): boolean {
  * can forward verbatim to the channel adapter.
  */
 export function looksLikeMSTeamsTargetId(raw: string): boolean {
-  const trimmed = raw.trim();
+  const trimmed = stripProviderPrefix(raw.trim()).trim();
   if (looksLikeMSTeamsConversationId(trimmed)) {
     return true;
   }