From 14f15cfed48bc7519e8e5eeac03f483f4b11ef3a Mon Sep 17 00:00:00 2001
From: Theo Browne <me@t3.gg>
Date: Wed, 2 Sep 2026 01:03:56 -0700
Subject: [PATCH] fix(server): stop titling linked PR threads from local git
 history (#9191)

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
---
 .../TextGenerationPrompts.test.ts              | 18 ++++++++++++++++++
 .../textGeneration/TextGenerationPrompts.ts    |  8 ++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/apps/server/src/textGeneration/TextGenerationPrompts.test.ts b/apps/server/src/textGeneration/TextGenerationPrompts.test.ts
index f382f9af09214ba54f877f5c176615978df014f1..253d88779827a4bb7bad9820971c0d8b7b06791e 100644
--- a/apps/server/src/textGeneration/TextGenerationPrompts.test.ts
+++ b/apps/server/src/textGeneration/TextGenerationPrompts.test.ts
@@ -188,6 +188,24 @@ describe("buildThreadTitlePrompt", () => {
     expect(result.prompt).toContain("67890 bytes");
   });
 
+  it.each([
+    { mode: "initial", previousTitle: undefined },
+    { mode: "regeneration", previousTitle: "Open Projects in Desktop App" },
+  ])(
+    "tells the $mode prompt not to title linked PRs from local git history",
+    ({ previousTitle }) => {
+      const result = buildThreadTitlePrompt({
+        message: "$takeover https://github.com/pingdotgg/t3code/pull/8588",
+        ...(previousTitle === undefined ? {} : { previousTitle }),
+      });
+
+      expect(result.prompt).toContain(
+        "Local git history is not evidence of what a linked PR or issue is about.",
+      );
+      expect(result.prompt).toContain('such as "Take Over PR 8588"');
+    },
+  );
+
   it("regenerates from recent thread contents and identifies the previous title", () => {
     const result = buildThreadTitlePrompt({
       message: `USER:\nInvestigate reconnect regressions\n\nASSISTANT:\nThe remaining issue is stale session state`,
diff --git a/apps/server/src/textGeneration/TextGenerationPrompts.ts b/apps/server/src/textGeneration/TextGenerationPrompts.ts
index c676a1760d0d0390a0e007a965eaa9a52c6a548b..b1c55939878a35727e2fe6abe6321f18e3d3019d 100644
--- a/apps/server/src/textGeneration/TextGenerationPrompts.ts
+++ b/apps/server/src/textGeneration/TextGenerationPrompts.ts
@@ -238,7 +238,9 @@ Editorial rules:
 - Do not copy and truncate the user's message.
 - Avoid project names already visible in the UI, quotes, labels, filler, and trailing punctuation.
 - Use attached images as primary context for UI issues.
-- When a URL or attachment is the only source of the subject, use available tools to inspect it. If it cannot be resolved, remain accurate rather than guessing.`;
+- When a URL or attachment is the only source of the subject, use available tools to inspect it directly.
+- Local git history is not evidence of what a linked PR or issue is about. Never title the thread after branch names, commit messages, or merged commits found in the checkout.
+- If a linked PR or issue cannot be read, fall back to the user's stated action plus its number, such as "Take Over PR 8588". This is the one case where a PR or issue number belongs in the title.`;
 
 function regenerateThreadTitlePrompt(previousTitle: string): string {
   return `Regenerate the title for an existing T3 Code thread so the user can recognize it weeks later.
@@ -265,7 +267,9 @@ Editorial rules:
 - Do not copy and truncate a thread message.
 - Avoid project names already visible in the UI, PR numbers, quotes, labels, filler, and trailing punctuation.
 - Use attached images as primary context for UI issues.
-- When a URL or attachment is the only source of the subject, use available tools to inspect it. If it cannot be resolved, remain accurate rather than guessing.
+- When a URL or attachment is the only source of the subject, use available tools to inspect it directly.
+- Local git history is not evidence of what a linked PR or issue is about. Never title the thread after branch names, commit messages, or merged commits found in the checkout.
+- If a linked PR or issue cannot be read, fall back to the user's stated action plus its number, such as "Take Over PR 8588". This is the one case where a PR or issue number belongs in the title.
 - Return a meaningfully improved title, not a cosmetic paraphrase of the previous title.
 
 Examples of the distinction:
-- 
2.54.0