fix(align): remove whole auto run between manual anchors on edit

Co-Authored-By: Claude Haiku 5.5 <[email protected]>

src/align/warp.ts

@@ -75,16 +75,17 @@ function checkSlot(left: Anchor | undefined, right: Anchor | undefined, a: Omit<
   if (right && !(a.midiSec < right.midiSec && a.audioSec < right.audioSec)) throw new Error("anchor would cross its right neighbour");
 }
 
-// Inserts a manual anchor at index `at` of an already-sorted list, then drops the immediate
-// neighbours of that anchor when they are auto. Never reaches past a manual anchor.
+// Inserts a manual anchor at index `at` of an already-sorted list. Removes the whole contiguous run of
+// auto anchors on each side, up to the nearest manual anchor (or the song start/end). Crossing checks
+// apply only against those manual neighbours, since the autos in between are removed.
 function insertManual(list: Anchor[], at: number, a: Omit<Anchor, "kind">): Anchor[] {
-  checkSlot(list[at - 1], list[at], a);
-  const out = [...list.slice(0, at), { midiSec: a.midiSec, audioSec: a.audioSec, kind: "manual" as const }, ...list.slice(at)];
-  const p = at;
-  const drop = new Set<number>();
-  if (p - 1 >= 0 && out[p - 1]!.kind === "auto") drop.add(p - 1);
-  if (p + 1 < out.length && out[p + 1]!.kind === "auto") drop.add(p + 1);
-  return sortedCopy(out.filter((_, i) => !drop.has(i)));
+  let l = at - 1;
+  while (l >= 0 && list[l]!.kind === "auto") l--;
+  let r = at;
+  while (r < list.length && list[r]!.kind === "auto") r++;
+  checkSlot(list[l], list[r], a);
+  const out = [...list.slice(0, l + 1), { midiSec: a.midiSec, audioSec: a.audioSec, kind: "manual" as const }, ...list.slice(r)];
+  return sortedCopy(out);
 }
 
 export function addManual(anchors: Anchor[], a: Omit<Anchor, "kind">): Anchor[] {

tests/align/warp.test.ts

@@ -108,17 +108,32 @@ describe("addManual", () => {
     expect(addManual([], { midiSec: 2, audioSec: 2.5 })).toEqual([M(2, 2.5)]);
   });
 
-  test("removes only the auto immediate neighbours, keeps manual ones and farther autos", () => {
-    // M0 | A2 | A4 | M8 ; insert manual at 6 -> A4 (immediate left, auto) goes; A2 stays (not adjacent); M8 stays
+  test("removes the whole contiguous auto run up to the nearest manual on each side", () => {
+    // M0 | A2 | A4 | M8 ; insert manual at 6 -> both autos between M0 and M8 go (the run stops at manuals)
     const base = [M(0, 0), A(2, 2), A(4, 4.5), M(8, 8)];
-    expect(addManual(base, { midiSec: 6, audioSec: 6.2 })).toEqual([
-      M(0, 0),
-      A(2, 2),
-      M(6, 6.2),
-      M(8, 8),
+    expect(addManual(base, { midiSec: 6, audioSec: 6.2 })).toEqual([M(0, 0), M(6, 6.2), M(8, 8)]);
+  });
+
+  test("autos every 2 s: adding a manual at 20 s removes autos between manuals at 10 s and 30 s only", () => {
+    const autos = [2, 4, 6, 8, 12, 14, 16, 18, 22, 24, 26, 28].map((t) => A(t, t));
+    const base = [...autos.slice(0, 4), M(10, 10), M(30, 30), ...autos.slice(4)].sort((x, y) => x.midiSec - y.midiSec);
+    // autos 12..28 sit between the manuals at 10 and 30 and go; 2..8 (before 10) are kept
+    expect(addManual(base, { midiSec: 20, audioSec: 20 })).toEqual([
+      A(2, 2), A(4, 4), A(6, 6), A(8, 8), M(10, 10), M(20, 20), M(30, 30),
     ]);
   });
 
+  test("moving a manual anchor across several autos succeeds and removes the crossed autos", () => {
+    // M0 | A10 | A20 | M30 | A40 | M60 ; move M30 -> midi 45 (crosses A40, stays before M60)
+    const base = [M(0, 0), A(10, 10), A(20, 20), M(30, 30), A(40, 40), M(60, 60)];
+    expect(moveAnchor(base, 3, { midiSec: 45, audioSec: 45 })).toEqual([M(0, 0), M(45, 45), M(60, 60)]);
+  });
+
+  test("auto runs are removed even when they are the only anchors besides the moved one", () => {
+    const base = [A(2, 2), A(4, 4), A(6, 6)];
+    expect(addManual(base, { midiSec: 5, audioSec: 5 })).toEqual([M(5, 5)]);
+  });
+
   test("keeps manual neighbours untouched", () => {
     const base = [M(0, 0), M(8, 8)];
     expect(addManual(base, { midiSec: 4, audioSec: 4 })).toEqual([M(0, 0), M(4, 4), M(8, 8)]);
@@ -158,9 +173,15 @@ describe("moveAnchor", () => {
     expect(() => moveAnchor(base, 1, { midiSec: 4, audioSec: 8.5 })).toThrow();
   });
 
-  test("throws when moved past an auto neighbour", () => {
+  test("moving past an auto neighbour is allowed; the crossed auto is removed", () => {
     const base = [M(0, 0), A(4, 4), M(8, 8)];
-    expect(() => moveAnchor(base, 2, { midiSec: 3, audioSec: 3 })).toThrow();
+    expect(moveAnchor(base, 2, { midiSec: 3, audioSec: 3 })).toEqual([M(0, 0), M(3, 3)]);
+  });
+
+  test("crossing a manual neighbour in audio time throws even with an auto between", () => {
+    const base = [M(0, 0), A(4, 4), M(8, 8), A(12, 12), M(16, 16)];
+    // Moving M(8) to audio 17 puts it past its right manual neighbour M(16) (audio 16); autos between are ignored.
+    expect(() => moveAnchor(base, 2, { midiSec: 10, audioSec: 17 })).toThrow();
   });
 
   test("throws on a bad index", () => {