fix(server): keep characters intact in generated commit subjects

packages/provider-core/src/server/textGenerationUtils.test.ts

@@ -0,0 +1,33 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import { sanitizeCommitSubject } from "./textGenerationUtils.ts";
+
+describe("sanitizeCommitSubject", () => {
+  it.each([
+    { name: "an emoji", prefixLength: 71, character: "🚀" },
+    { name: "an accented character", prefixLength: 71, character: "e\u0301" },
+    { name: "an emoji with a skin tone", prefixLength: 70, character: "👍🏽" },
+    { name: "a flag", prefixLength: 69, character: "🇮🇹" },
+    { name: "a joined emoji", prefixLength: 65, character: "👨‍👩‍👧‍👦" },
+  ])("keeps $name intact at the subject limit", ({ prefixLength, character }) => {
+    const prefix = "a".repeat(prefixLength);
+
+    expect(sanitizeCommitSubject(`${prefix}${character} more`)).toBe(prefix);
+  });
+
+  it("keeps a complete character that ends exactly at the limit", () => {
+    const expected = `${"a".repeat(70)}🚀`;
+
+    expect(sanitizeCommitSubject(`${expected} more`)).toBe(expected);
+  });
+
+  it("uses the existing fallback when a single character exceeds the limit", () => {
+    expect(sanitizeCommitSubject(`a${"\u0301".repeat(72)} more`)).toBe("Update project files");
+  });
+
+  it("keeps the existing ASCII limit and subject normalization", () => {
+    expect(sanitizeCommitSubject("a".repeat(80))).toBe("a".repeat(72));
+    expect(sanitizeCommitSubject("  Fix tests...\nignored  ")).toBe("Fix tests");
+    expect(sanitizeCommitSubject("...")).toBe("Update project files");
+  });
+});

packages/provider-core/src/server/textGenerationUtils.ts

@@ -40,7 +40,15 @@ export function sanitizeCommitSubject(raw: string): string {
   if (withoutTrailingPeriod.length <= 72) {
     return withoutTrailingPeriod;
   }
-  return withoutTrailingPeriod.slice(0, 72).trimEnd();
+  const segments = new Intl.Segmenter(undefined, { granularity: "grapheme" }).segment(
+    withoutTrailingPeriod,
+  );
+  let subject = "";
+  for (const { segment } of segments) {
+    if (subject.length + segment.length > 72) break;
+    subject += segment;
+  }
+  return subject.trimEnd() || "Update project files";
 }
 
 /** Normalise a raw PR title to a single line with a sensible fallback. */