diff --git a/extensions/msteams/src/monitor-handler/message-handler.authz.test.ts b/extensions/msteams/src/monitor-handler/message-handler.authz.test.ts
index e54cb355468..fdc8fb0e9d3 100644
--- a/extensions/msteams/src/monitor-handler/message-handler.authz.test.ts
+++ b/extensions/msteams/src/monitor-handler/message-handler.authz.test.ts
@@ -651,6 +651,7 @@ describe("msteams monitor handler authz", () => {
     expect(dispatched?.ctxPayload).toMatchObject({
       BodyForAgent:
         "[Thread history]\nAlice: Allowed context\n[/Thread history]\n\nCurrent message",
+      GroupSpace: "team123",
     });
     expect(
       String((dispatched?.ctxPayload as { BodyForAgent?: string }).BodyForAgent),
diff --git a/extensions/msteams/src/monitor-handler/message-handler.ts b/extensions/msteams/src/monitor-handler/message-handler.ts
index b50ad9ae076..e304059314e 100644
--- a/extensions/msteams/src/monitor-handler/message-handler.ts
+++ b/extensions/msteams/src/monitor-handler/message-handler.ts
@@ -773,6 +773,7 @@ export function createMSTeamsMessageHandler(deps: MSTeamsMessageHandlerDeps) {
       ChatType: isDirectMessage ? "direct" : isChannel ? "channel" : "group",
       ConversationLabel: envelopeFrom,
       GroupSubject: !isDirectMessage ? conversationType : undefined,
+      GroupSpace: teamId,
       SenderName: senderName,
       SenderId: senderId,
       Provider: "msteams" as const,
diff --git a/extensions/slack/src/monitor/message-handler/prepare.test.ts b/extensions/slack/src/monitor/message-handler/prepare.test.ts
index e03a92fba2f..56f60f38060 100644
--- a/extensions/slack/src/monitor/message-handler/prepare.test.ts
+++ b/extensions/slack/src/monitor/message-handler/prepare.test.ts
@@ -196,6 +196,7 @@ describe("slack prepareSlackMessage inbound contract", () => {
 
     expect(prepared).toBeTruthy();
     expectInboundContextContract(prepared!.ctxPayload as any);
+    expect(prepared!.ctxPayload.GroupSpace).toBe("T1");
   });
 
   it("does not enable Slack status reactions when the message timestamp is missing", async () => {
diff --git a/extensions/slack/src/monitor/message-handler/prepare.ts b/extensions/slack/src/monitor/message-handler/prepare.ts
index 43dfaf44464..d753dd2dde8 100644
--- a/extensions/slack/src/monitor/message-handler/prepare.ts
+++ b/extensions/slack/src/monitor/message-handler/prepare.ts
@@ -736,6 +736,7 @@ export async function prepareSlackMessage(params: {
     ChatType: isDirectMessage ? "direct" : "channel",
     ConversationLabel: envelopeFrom,
     GroupSubject: isRoomish ? roomLabel : undefined,
+    GroupSpace: ctx.teamId || undefined,
     GroupSystemPrompt: groupSystemPrompt,
     UntrustedContext: untrustedChannelMetadata ? [untrustedChannelMetadata] : undefined,
     SenderName: senderName,
diff --git a/extensions/slack/src/monitor/slash.test.ts b/extensions/slack/src/monitor/slash.test.ts
index ce70282f791..b4f8eb77ee0 100644
--- a/extensions/slack/src/monitor/slash.test.ts
+++ b/extensions/slack/src/monitor/slash.test.ts
@@ -983,9 +983,10 @@ describe("slack slash command session metadata", () => {
     expect(recordSessionMetaFromInboundMock).toHaveBeenCalledTimes(1);
     const call = recordSessionMetaFromInboundMock.mock.calls[0]?.[0] as {
       sessionKey?: string;
-      ctx?: { OriginatingChannel?: string };
+      ctx?: { GroupSpace?: string; OriginatingChannel?: string };
     };
     expect(call.ctx?.OriginatingChannel).toBe("slack");
+    expect(call.ctx?.GroupSpace).toBe("T1");
     expect(call.sessionKey).toBeDefined();
   });
 
diff --git a/extensions/slack/src/monitor/slash.ts b/extensions/slack/src/monitor/slash.ts
index b6f5e2966b6..e29689f6e8b 100644
--- a/extensions/slack/src/monitor/slash.ts
+++ b/extensions/slack/src/monitor/slash.ts
@@ -577,6 +577,7 @@ export async function registerSlackMonitorSlashCommands(params: {
                 : `slack:group:${command.channel_id}`,
           }) ?? (isDirectMessage ? senderName : roomLabel),
         GroupSubject: isRoomish ? roomLabel : undefined,
+        GroupSpace: ctx.teamId || undefined,
         GroupSystemPrompt: groupSystemPrompt,
         UntrustedContext: untrustedChannelMetadata ? [untrustedChannelMetadata] : undefined,
         SenderName: senderName,