refactor: share paren-aware chunk break scan

src/auto-reply/chunk.test.ts

@@ -25,6 +25,45 @@ function expectFencesBalanced(chunks: string[]) {
   }
 }
 
+type ChunkCase = {
+  name: string;
+  text: string;
+  limit: number;
+  expected: string[];
+};
+
+function runChunkCases(
+  chunker: (text: string, limit: number) => string[],
+  cases: ChunkCase[],
+) {
+  for (const { name, text, limit, expected } of cases) {
+    it(name, () => {
+      expect(chunker(text, limit)).toEqual(expected);
+    });
+  }
+}
+
+const parentheticalCases: ChunkCase[] = [
+  {
+    name: "keeps parenthetical phrases together",
+    text: "Heads up now (Though now I'm curious)ok",
+    limit: 35,
+    expected: ["Heads up now", "(Though now I'm curious)ok"],
+  },
+  {
+    name: "handles nested parentheses",
+    text: "Hello (outer (inner) end) world",
+    limit: 26,
+    expected: ["Hello (outer (inner) end)", "world"],
+  },
+  {
+    name: "ignores unmatched closing parentheses",
+    text: "Hello) world (ok)",
+    limit: 12,
+    expected: ["Hello)", "world (ok)"],
+  },
+];
+
 describe("chunkText", () => {
   it("keeps multi-line text in one chunk when under limit", () => {
     const text = "Line one\n\nLine two\n\nLine three";
@@ -68,11 +107,7 @@ describe("chunkText", () => {
     expect(chunks).toEqual(["Supercalif", "ragilistic", "expialidoc", "ious"]);
   });
 
-  it("keeps parenthetical phrases together", () => {
-    const text = "Heads up now (Though now I'm curious)ok";
-    const chunks = chunkText(text, 35);
-    expect(chunks).toEqual(["Heads up now", "(Though now I'm curious)ok"]);
-  });
+  runChunkCases(chunkText, [parentheticalCases[0]]);
 });
 
 describe("resolveTextChunkLimit", () => {
@@ -191,17 +226,7 @@ describe("chunkMarkdownText", () => {
     }
   });
 
-  it("keeps parenthetical phrases together", () => {
-    const text = "Heads up now (Though now I'm curious)ok";
-    const chunks = chunkMarkdownText(text, 35);
-    expect(chunks).toEqual(["Heads up now", "(Though now I'm curious)ok"]);
-  });
-
-  it("handles nested parentheses", () => {
-    const text = "Hello (outer (inner) end) world";
-    const chunks = chunkMarkdownText(text, 26);
-    expect(chunks).toEqual(["Hello (outer (inner) end)", "world"]);
-  });
+  runChunkCases(chunkMarkdownText, parentheticalCases);
 
   it("hard-breaks when a parenthetical exceeds the limit", () => {
     const text = `(${"a".repeat(80)})`;
@@ -209,10 +234,4 @@ describe("chunkMarkdownText", () => {
     expect(chunks[0]?.length).toBe(20);
     expect(chunks.join("")).toBe(text);
   });
-
-  it("ignores unmatched closing parentheses", () => {
-    const text = "Hello) world (ok)";
-    const chunks = chunkMarkdownText(text, 12);
-    expect(chunks).toEqual(["Hello)", "world (ok)"]);
-  });
 });

src/auto-reply/chunk.ts

@@ -91,23 +91,7 @@ export function chunkText(text: string, limit: number): string[] {
     const window = remaining.slice(0, limit);
 
     // 1) Prefer a newline break inside the window (outside parentheses).
-    let lastNewline = -1;
-    let lastWhitespace = -1;
-    let depth = 0;
-    for (let i = 0; i < window.length; i++) {
-      const char = window[i];
-      if (char === "(") {
-        depth += 1;
-        continue;
-      }
-      if (char === ")" && depth > 0) {
-        depth -= 1;
-        continue;
-      }
-      if (depth !== 0) continue;
-      if (char === "\n") lastNewline = i;
-      else if (/\s/.test(char)) lastWhitespace = i;
-    }
+    const { lastNewline, lastWhitespace } = scanParenAwareBreakpoints(window);
 
     // 2) Otherwise prefer the last whitespace (word boundary) inside the window.
     let breakIdx = lastNewline > 0 ? lastNewline : lastWhitespace;
@@ -243,12 +227,26 @@ function pickSafeBreakIndex(
   window: string,
   spans: ReturnType<typeof parseFenceSpans>,
 ): number {
+  const { lastNewline, lastWhitespace } = scanParenAwareBreakpoints(
+    window,
+    (index) => isSafeFenceBreak(spans, index),
+  );
+
+  if (lastNewline > 0) return lastNewline;
+  if (lastWhitespace > 0) return lastWhitespace;
+  return -1;
+}
+
+function scanParenAwareBreakpoints(
+  window: string,
+  isAllowed: (index: number) => boolean = () => true,
+): { lastNewline: number; lastWhitespace: number } {
   let lastNewline = -1;
   let lastWhitespace = -1;
   let depth = 0;
 
   for (let i = 0; i < window.length; i++) {
-    if (!isSafeFenceBreak(spans, i)) continue;
+    if (!isAllowed(i)) continue;
     const char = window[i];
     if (char === "(") {
       depth += 1;
@@ -263,7 +261,5 @@ function pickSafeBreakIndex(
     else if (/\s/.test(char)) lastWhitespace = i;
   }
 
-  if (lastNewline > 0) return lastNewline;
-  if (lastWhitespace > 0) return lastWhitespace;
-  return -1;
+  return { lastNewline, lastWhitespace };
 }