[Copilot]

Tapping the greyed-out Undo button with an empty undo stack still played the undo animation. It should do nothing on any platform while the stack is empty.

Cause

Since #4013, undo declares isActive: isUndoEnabled in place of canExecute. Without canExecute, the command always counts as executable, so Cmd+Z always calls preventDefault and blocks native undo (#3879). Two side effects on the toolbar:

• Undo always counts as executable, so tapping it while greyed out runs a no-op undo and animates the icon.
• ToolbarButton animates a command that has isActive only when it goes from inactive to active. As a result, a real undo never animated, and the animation only ever played on the wrong tap.

Change

• src/commands/undo.ts:

  • Restores canExecute: isUndoEnabled.
  • Adds the existing preventDefault: true flag, which keyDown honours even when canExecute is false, so Cmd+Z still always swallows native undo.
  • Drops isActive.

  canExecute: state => isUndoEnabled(state),
  // Always call e.preventDefault() to block native undo, even when there is nothing to undo.
  preventDefault: true,

• Resulting behaviour:

  • Toolbar and Command Center: the Undo button can't be tapped while the stack is empty.
  • The command palette lists Undo as disabled while the stack is empty.
  • A successful undo now animates the icon, matching Redo.
  • Undo no longer gets the Command Center "active" glow, matching Redo.
  • Unchanged: native history gestures (handleNativeHistory checks isUndoEnabled directly) and long-press opening the UndoSlider.

Test

• src/e2e/puppeteer/__tests__/undo.ts (mobile):
  • Taps Undo on an empty stack and expects zero animation mounts.
  • Then makes an edit and expects exactly one mount when Undo is tapped. This positive control shows the first tap actually reached the button.
  • Counts mounts with a MutationObserver, because under Puppeteer LottieAnimation jumps to its last frame and unmounts as soon as it's ready. Reading the DOM after the tap would miss it.

• Fixes Toolbar: Greyed-out Undo button can be tapped when there is nothing to undo #5994

[github-actions]

Preview Deployment · Oct 23, 2026, 12:14 AM UTC · 5a5ac4f

[BayuAri]

Confirmed fixed.
Undo button is disabled on first open and when there is no Undo Stack to execute accordingly

[trevinhofmann]

This change results in the Undo toolbar button being disabled for ~500ms on the first edit due to the text edit throttling.

Can you please resolve this? One option to consider is updating Editable.tsx to commit the first edit immediately by adding isUndoEnabled as one of the conditions here:

em/src/components/Editable.tsx

Lines 848 to 855 in a80340a

	wrappedValue !== incomingValue ||
	emojiSpaceAdded ||
	transient ||
	contextLengthChange ||
	urlChange ||
	formattingChange ||
	isEmpty ||
	isDivider(newValue)

Case to reproduce below (please also add as a test case, if feasible... not sure if we have a nice way to simulate reloading the app / starting with a thought but an empty history):

1. Create a thought Hello
2. Reload the application
3. Place the cursor at the end of Hello and type W (becoming HelloW)

Result: The "Undo" button is disabled for ~500ms until becoming active and working

Expected: The "Undo" button should become immediately active, as it does in main.

[Copilot]

Fixed in 3f1deef. I used your suggestion: Editable now commits an edit immediately when !isUndoEnabled(state), so the first keystroke after a reload enables Undo right away.

• Undo grouping: unchanged. Typing World after a reload and tapping Undo once still returns to Hello, because the undo history merges the immediate edit with the throttled edits that follow it.
• Test: added to src/e2e/puppeteer/__tests__/undo.ts (mobile, persistent storage). It reloads, types W at the end of Hello, taps Undo right away, and expects Hello. Before the fix it failed with expected 'HelloW' to be 'Hello'.
• Side effect on desktop: the first keystroke after a reload now starts the distraction-free toolbar fade about 500ms sooner, the same as edits that already commit immediately (URLs, formatting).
• Docs: docs/commands.md "Flushing pending edits" now describes this exception to the throttle.

[trevinhofmann]

@copilot - Can you please address this review comment and resolve the defect?

#6082 (comment)

[trevinhofmann]

LGTM, thank you!

[raineorshine]

The Lottie animation is a side effect of the undo button being enabled when it shouldn’t. While it makes sense as a proxy for the actual issue, it is not a good candidate for automated testing. It’s big and slow, and too tightly coupled to animation implementation details. Unfortunately the agent didn’t pick up on this distinction.

I would completey remove both of these tests.

5a5ac4f