diff --git a/apps/server/src/textGeneration/TextGenerationPrompts.ts b/apps/server/src/textGeneration/TextGenerationPrompts.ts
index 6015e83b5d4..17277c04894 100644
--- a/apps/server/src/textGeneration/TextGenerationPrompts.ts
+++ b/apps/server/src/textGeneration/TextGenerationPrompts.ts
@@ -38,7 +38,10 @@ export function buildCommitMessagePrompt(input: CommitMessagePromptInput) {
       ? "Return a JSON object with keys: subject, body, branch."
       : "Return a JSON object with keys: subject, body.",
     "Rules:",
-    "- subject must be imperative, <= 72 chars, and no trailing period",
+    "- subject must follow Conventional Commits format: type(scope): description",
+    "- type must be one of: feat, fix, docs, style, refactor, test, chore",
+    "- scope is optional; description is imperative, no trailing period",
+    "- full subject line must be <= 72 chars",
     "- body can be empty string or short bullet points",
     ...(wantsBranch
       ? ["- branch must be a short semantic git branch fragment for this change"]