From 0a67f227e14bfb980730dae659df438e0127f81f Mon Sep 17 00:00:00 2001
From: Alex Southwell <4596216+saphid@users.noreply.github.com>
Date: Mon, 2 Nov 2026 18:56:52 +1100
Subject: [PATCH] fix(server): create_threads titles no longer end in a broken
 character

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 apps/server/src/mcp/OrchestratorMcpService.test.ts | 8 ++++++++
 apps/server/src/mcp/OrchestratorMcpService.ts      | 9 ++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/apps/server/src/mcp/OrchestratorMcpService.test.ts b/apps/server/src/mcp/OrchestratorMcpService.test.ts
index 47a6bda166ce1..328d32f635685 100644
--- a/apps/server/src/mcp/OrchestratorMcpService.test.ts
+++ b/apps/server/src/mcp/OrchestratorMcpService.test.ts
@@ -2037,6 +2037,14 @@ describe("OrchestratorMcpService provider resolution", () => {
               ...request,
               clientRequestId: "empty",
             });
+            const emojiAtLimit = yield* service.createThreads(scope, {
+              threads: [{ ...request.threads[0]!, prompt: `${"a".repeat(76)}😀 and more work.` }],
+              clientRequestId: "emoji-title",
+            });
+            const titled = yield* orchestrator.getThreadProjection(
+              emojiAtLimit.threads[0]!.threadId,
+            );
+            assert.equal(titled.thread.title, `${"a".repeat(76)}...`);
 
             yield* settings.updateSettings({
               projectSettingsOverrides: {
diff --git a/apps/server/src/mcp/OrchestratorMcpService.ts b/apps/server/src/mcp/OrchestratorMcpService.ts
index 910a1531aedb8..108ab946245a0 100644
--- a/apps/server/src/mcp/OrchestratorMcpService.ts
+++ b/apps/server/src/mcp/OrchestratorMcpService.ts
@@ -742,7 +742,14 @@ function threadTitle(input: {
 }): string {
   const detail = input.title?.trim() || input.prompt?.trim();
   if (!detail) return `${input.parentTitle} thread ${input.index + 1}`;
-  return detail.length > 80 ? `${detail.slice(0, 77)}...` : detail;
+  if (detail.length <= 80) return detail;
+  let end = 77;
+  const previous = detail.charCodeAt(end - 1);
+  const next = detail.charCodeAt(end);
+  if (previous >= 0xd800 && previous <= 0xdbff && next >= 0xdc00 && next <= 0xdfff) {
+    end -= 1;
+  }
+  return `${detail.slice(0, end)}...`;
 }
 
 function threadSettlement(