@@ -23,10 +23,15 @@ export function collapseToolOutput(output: string, maxLines: number, maxChars: n
   return { output: preview, overflow: true }
 }
 
-/** Lines of a patch without its file headers, which is what a unified diff view renders. */
+/** Lines of a patch without its file and hunk headers, which is what a unified diff view renders. */
 export function patchBodyLines(patch: string) {
   const start = patch.search(/^@@ /m)
-  return start === -1 ? 0 : patch.slice(start).trimEnd().split("\n").length
+  if (start === -1) return 0
+  return patch
+    .slice(start)
+    .trimEnd()
+    .split("\n")
+    .filter((line) => !line.startsWith("@@") && !line.startsWith("\\")).length
 }
 
 export function collapseShellOutput(input: string, output: string, maxLines: number, maxChars: number) {
 
@@ -16,6 +16,7 @@ test("limits command input and output to the same line budget", () => {
 test("counts patch lines without the file headers", () => {
   const patch = ["Index: a.ts", "===", "--- a.ts", "+++ a.ts", "@@ -1,2 +1,2 @@", "-one", "+uno", " two", ""].join("\n")
 
-  expect(patchBodyLines(patch)).toBe(4)
+  expect(patchBodyLines(patch)).toBe(3)
+  expect(patchBodyLines(`${patch.trimEnd()}\n@@ -9 +9 @@\n-x\n+y\n\\ No newline at end of file`)).toBe(5)
   expect(patchBodyLines("Index: a.ts\n")).toBe(0)
 })