1 files changed, 50 insertions, 0 deletions
diff --git a/apps/web/src/commands/timeline/element/shift-split-remainder.ts b/apps/web/src/commands/timeline/element/shift-split-remainder.ts
new file mode 100644
index 00000000..3799c8f9
--- /dev/null
+++ b/apps/web/src/commands/timeline/element/shift-split-remainder.ts
@@ -0,0 +1,50 @@
+import { Command, type CommandResult } from "@/commands/base-command";
+import type { MediaTime } from "@/wasm";
+import { MoveElementCommand } from "./move-elements";
+import type { SplitElementsCommand } from "./split-elements";
+
+/**
+ * Moves the right-side elements produced by a SplitElementsCommand to a new
+ * start time. Must run after the split inside a BatchCommand: the right-side
+ * element ids only exist once the split has executed. Rebuilds the inner move
+ * on every execute() so redo picks up the fresh ids a re-executed split
+ * generates.
+ */
+export class ShiftSplitRemainderCommand extends Command {
+	private inner: MoveElementCommand | null = null;
+
+	constructor({
+		split,
+		newStartTime,
+	}: {
+		split: SplitElementsCommand;
+		newStartTime: MediaTime;
+	}) {
+		super();
+		this.split = split;
+		this.newStartTime = newStartTime;
+	}
+
+	private readonly split: SplitElementsCommand;
+	private readonly newStartTime: MediaTime;
+
+	execute(): CommandResult | undefined {
+		const rightSideElements = this.split.getRightSideElements();
+		if (rightSideElements.length === 0) {
+			return undefined;
+		}
+		this.inner = new MoveElementCommand({
+			moves: rightSideElements.map((element) => ({
+				sourceTrackId: element.trackId,
+				targetTrackId: element.trackId,
+				elementId: element.elementId,
+				newStartTime: this.newStartTime,
+			})),
+		});
+		return this.inner.execute();
+	}
+
+	undo(): void {
+		this.inner?.undo();
+	}
+}