fix(maestro): align structured diff hunks

web/src/structuredDiff.test.ts

@@ -78,6 +78,25 @@ describe("computeDiffLines", () => {
     ]);
   });
 
+  it("marks an unchanged unterminated final context line", () => {
+    expect(texts(computeDiffLines("a\nb\nc", "a\nX\nc"))).toEqual([
+      ["ctx", "a"],
+      ["del", "b"],
+      ["add", "X"],
+      ["ctx", "c"],
+      ["eof", "\\ No newline at end of file"],
+    ]);
+  });
+
+  it("marks an unterminated new file only once", () => {
+    const lines = computeDiffLines(null, "a");
+    expect(texts(lines)).toEqual([
+      ["add", "a"],
+      ["eof", "\\ No newline at end of file"],
+    ]);
+    expect(lines.filter((line) => line.kind === "eof")).toHaveLength(1);
+  });
+
   it("collapses a long unchanged interior run, keeping 3 lines of context each side", () => {
     const common = Array.from({ length: 20 }, (_, i) => `line${i}`);
     const oldText = [...common.slice(0, 10), "OLD", ...common.slice(10)].join("\n");
@@ -111,9 +130,10 @@ describe("computeDiffLines", () => {
       ["ctx", "lead0"],
       ["ctx", "lead1"],
     ]);
-    expect(texts(lines).slice(-2)).toEqual([
+    expect(texts(lines).slice(-3)).toEqual([
       ["ctx", "trail0"],
       ["ctx", "trail1"],
+      ["eof", "\\ No newline at end of file"],
     ]);
   });