Clear undo/redo history a library referenced in the stack is being removed

chrome/content/zotero/xpcom/data/library.js

@@ -683,6 +683,13 @@ Zotero.Library.prototype._eraseData = async function (env) {
 	await Zotero.DB.queryAsync("DELETE FROM libraries WHERE libraryID=?", this.libraryID);
 	// TODO: Emit event so this doesn't have to be here
 	await Zotero.Fulltext.clearLibraryVersion(this.libraryID);
+
+	// Discard undo/redo history that references this library
+	if (Zotero.UndoHistory) {
+		Zotero.DB.addCurrentCallback('commit', function () {
+			Zotero.UndoHistory.clearForLibrary(this.libraryID);
+		}.bind(this));
+	}
 };
 
 Zotero.Library.prototype._finalizeErase = async function (env) {

chrome/content/zotero/xpcom/undoHistory.js

@@ -58,6 +58,17 @@ Zotero.UndoHistory = {
 		this._pendingEntry = null;
 	},
 
+	/**
+	 * Discard both stacks if any entry references an object in the given library.
+	 * @param {Integer} libraryID
+	 */
+	clearForLibrary(libraryID) {
+		let affectsLibrary = entry => entry.changes.some(change => change.libraryID === libraryID);
+		if (this._undoStack.some(affectsLibrary) || this._redoStack.some(affectsLibrary)) {
+			this.clear();
+		}
+	},
+
 	/**
 	 * Return a window controller for cmd_undo/cmd_redo that defers to
 	 * native text-editing controllers when they are active.

test/tests/undoHistoryTest.js

@@ -281,6 +281,58 @@ describe("Zotero.UndoHistory", function () {
 		});
 	});
 
+	describe("library erasure", function () {
+		it("should clear undo history when a related library is erased", async function () {
+			let group = await createGroup();
+			let collection = await createDataObject(
+				'collection', { libraryID: group.libraryID, name: 'Group Collection' }
+			);
+			Zotero.UndoHistory.clear();
+
+			collection.name = 'Renamed';
+			await collection.saveTx({ undoAction: 'undo-action-rename-collection' });
+			assert.isTrue(Zotero.UndoHistory.canUndo());
+
+			// The group's objects are cascade-deleted without per-object events, so
+			// the related undo entry must be discarded
+			await group.eraseTx();
+			assert.isFalse(Zotero.UndoHistory.canUndo());
+			assert.isFalse(Zotero.UndoHistory.canRedo());
+		});
+
+		it("should clear undo history when the erased library is referenced only in the redo stack", async function () {
+			let group = await createGroup();
+			let collection = await createDataObject(
+				'collection', { libraryID: group.libraryID, name: 'Group Collection' }
+			);
+			Zotero.UndoHistory.clear();
+
+			collection.name = 'Renamed';
+			await collection.saveTx({ undoAction: 'undo-action-rename-collection' });
+			// Move the entry onto the redo stack
+			await Zotero.UndoHistory.undo();
+			assert.isTrue(Zotero.UndoHistory.canRedo());
+
+			await group.eraseTx();
+			assert.isFalse(Zotero.UndoHistory.canRedo());
+			assert.isFalse(Zotero.UndoHistory.canUndo());
+		});
+
+		it("should preserve undo history when an unrelated library is erased", async function () {
+			// Record an undo entry in the user library
+			let collection = await createDataObject('collection', { name: 'My Library Collection' });
+			Zotero.UndoHistory.clear();
+			collection.name = 'Renamed';
+			await collection.saveTx({ undoAction: 'undo-action-rename-collection' });
+			assert.isTrue(Zotero.UndoHistory.canUndo());
+
+			// Erasing an unrelated group must not touch the user-library history
+			let group = await createGroup();
+			await group.eraseTx();
+			assert.isTrue(Zotero.UndoHistory.canUndo());
+		});
+	});
+
 	describe("canUndo/canRedo", function () {
 		it("should return false when stacks are empty", function () {
 			assert.isFalse(Zotero.UndoHistory.canUndo());