feat: expose clearHistory() to reset the undo/redo stack by DisciplinedSoftware · Pull Request #373 · SSShooter/mind-elixir-core

DisciplinedSoftware · 2026-03-10T05:01:47Z

Motivation

When an application loads new data into an existing MindElixir instance via refresh(), the internal undo/redo history still contains snapshots from the previous diagram. This lets users press Ctrl+Z and silently travel back into an earlier diagram's state — a confusing and data-loss-prone experience.

A host needs a way to discard that stale history after loading new data.

Changes

`src/plugin/operationHistory.ts`

Adds mei.clearHistory(), which:

clears the history array
resets currentIndex to -1
re-captures current from mei.getData() so the fresh snapshot is the new undo baseline

`src/types/index.ts`

Declares clearHistory: () => void on MindElixirInstance with a JSDoc comment explaining its purpose.

Usage

mind.refresh(newData)
mind.clearHistory() // users can no longer undo back into the previous diagram

Adds a clearHistory() method to the operationHistory plugin that resets the undo/redo stack to an empty state with a fresh baseline snapshot. This is needed by hosts that load new data into an existing MindElixir instance (e.g. via refresh()) and want to prevent users from undoing back into the previous diagram's state.

gemini-code-assist · 2026-03-10T05:01:59Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a potential data-loss and confusing user experience when an application refreshes a MindElixir instance with new data. By exposing a new clearHistory() method, it provides a mechanism for applications to reset the undo/redo stack, ensuring that users cannot inadvertently revert to the state of a previously loaded diagram.

Highlights

New clearHistory() method: Introduced mei.clearHistory() to allow hosts to discard stale undo/redo history after loading new data, preventing users from undoing into previous diagram states.
clearHistory() implementation: The clearHistory() method clears the internal history array, resets currentIndex to -1, and captures the current diagram state as the new undo baseline.
Type definition and documentation: Added clearHistory: () => void to the MindElixirInstance interface in src/types/index.ts with a detailed JSDoc comment.

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Changelog

src/plugin/operationHistory.ts
- Implemented the clearHistory method on the MindElixirInstance to reset the undo/redo history.
src/types/index.ts
- Added the clearHistory method signature and JSDoc documentation to the MindElixirInstance interface.

Activity

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Code Review

This pull request introduces a clearHistory() method to the MindElixir instance, allowing users to reset the undo/redo stack after loading new data. No security vulnerabilities were found. However, there is a type safety concern where the MindElixirInstance interface defines clearHistory as a mandatory method, but its runtime assignment is conditional on the allowUndo option, which could lead to runtime errors if invoked when allowUndo is false.

gemini-code-assist · 2026-03-10T05:03:34Z

src/types/index.ts

+  /**
+   * Reset the undo/redo stack and update the internal baseline snapshot to the
+   * current diagram state. Call this after loading new data into an existing
+   * instance (e.g. after `refresh()`) to prevent users from undoing back into
+   * a previously loaded diagram.
+   */
+  clearHistory: () => void


The clearHistory method is declared as mandatory in the MindElixirInstance interface. However, its implementation in src/plugin/operationHistory.ts is only applied to the instance if the allowUndo option is true (as seen in src/methods.ts, line 94). If allowUndo is false, mei.clearHistory will not be defined at runtime, which could lead to a TypeError if the method is called, despite the type definition indicating its presence. To prevent this type-runtime mismatch, clearHistory should be marked as optional in the interface.

Suggested change

/**

* Reset the undo/redo stack and update the internal baseline snapshot to the

* current diagram state. Call this after loading new data into an existing

* instance (e.g. after `refresh()`) to prevent users from undoing back into

* a previously loaded diagram.

*/

clearHistory: () => void

/**

* Reset the undo/redo stack and update the internal baseline snapshot to the

* current diagram state. Call this after loading new data into an existing

* instance (e.g. after `refresh()`) to prevent users from undoing back into

* a previously loaded diagram.

*/

clearHistory?: () => void

Fixed in 15a42c9 — changed to clearHistory?: () => void and updated the JSDoc to note that it is only available when allowUndo is true.

Copilot

Pull request overview

This PR adds a public API to reset MindElixir’s undo/redo history after loading new data into an existing instance (e.g., via refresh()), preventing users from undoing back into a previously loaded diagram.

Changes:

Add mei.clearHistory() to clear the operation history stack and re-baseline the “current” snapshot.
Extend MindElixirInstance typings with a documented clearHistory() method.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
`src/plugin/operationHistory.ts`	Implements `mei.clearHistory()` to reset internal history state and baseline snapshot.
`src/types/index.ts`	Exposes `clearHistory(): void` on the public `MindElixirInstance` type with JSDoc guidance.

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Copilot · 2026-03-10T05:05:00Z

src/types/index.ts

+   * instance (e.g. after `refresh()`) to prevent users from undoing back into
+   * a previously loaded diagram.
+   */
+  clearHistory: () => void


clearHistory is declared as a required method on MindElixirInstance, but it’s only assigned inside the operationHistory plugin (and that plugin is skipped when allowUndo is false and in lite mode). This makes the type contract unsafe for consumers because mind.clearHistory() can be undefined at runtime. Consider either (a) making clearHistory optional in the interface, or (b) defining a default no-op implementation on the instance/prototype so it always exists regardless of allowUndo/build mode.

Suggested change

clearHistory: () => void

clearHistory?: () => void

Fixed in 15a42c9 — changed to clearHistory?: () => void and updated the JSDoc to note that it is only available when allowUndo is true.

Copilot · 2026-03-10T05:05:00Z

src/plugin/operationHistory.ts

+  mei.clearHistory = function () {
+    history = []
+    currentIndex = -1
+    current = mei.getData()


clearHistory() clears the history stack but leaves currentSelectedNodes unchanged. Since the intended usage is right after refresh(), selection is typically cleared, and the next operation may incorrectly record the previous diagram’s selected node IDs in currentSelected, which can break selection restoration on undo/redo. Reset currentSelectedNodes inside clearHistory() (e.g., derive it from mei.currentNodes) or update the selection tracking to handle deselection events as well.

Suggested change

current = mei.getData()

current = mei.getData()

// keep cached selection in sync with current diagram state

currentSelectedNodes = mei.currentNodes.map(n => n.nodeObj)

Fixed in 601dc4b — added currentSelectedNodes = [] to clearHistory() so stale node IDs from the previous diagram cannot affect selection restoration after refresh() + clearHistory().

Copilot · 2026-03-10T05:05:00Z

src/plugin/operationHistory.ts

+  mei.clearHistory = function () {
+    history = []
+    currentIndex = -1
+    current = mei.getData()
+  }


No automated test is added for the new clearHistory() behavior. There are existing Playwright specs covering operation history/undo/redo; please add a test that (1) performs some operations, (2) calls refresh(newData) + clearHistory(), then (3) asserts that undo/redo cannot revert into the pre-refresh diagram and that the first undo baseline is the refreshed data.

Added in 1e50bf0 — new file tests/clear-history.spec.ts with three Playwright tests:

Undo cannot revert into the pre-refresh diagram — performs ops on diagram A, calls refresh(B) + clearHistory(), then asserts Ctrl+Z/Ctrl+Y are no-ops across the diagram boundary.

Operations after clearHistory() are undoable normally — verifies that new operations on diagram B undo/redo correctly, and that the stack doesn't reach back into diagram A.

First undo baseline is the refreshed state — verifies that undoing the first post-refresh operation lands exactly on the refreshed diagram, not an earlier one.

…iew fixes - Reset currentSelectedNodes to [] so stale selection IDs from the previous diagram cannot corrupt undo/redo selection restoration after a refresh + clearHistory() call. - (types updated in next commit to mark clearHistory as optional)

clearHistory is only registered by the operationHistory plugin, which is skipped when allowUndo is false. Declaring it as a required method would be a type-runtime mismatch. Mark it optional and update the JSDoc to mention the allowUndo prerequisite.

DisciplinedSoftware · 2026-03-10T05:10:39Z

Thank you both for the reviews! Fixed in the two follow-up commits:

clearHistory?: () => void (optional) — changed in 15a42c9. The JSDoc now also explicitly notes that clearHistory is only available when allowUndo is true.

currentSelectedNodes reset — added currentSelectedNodes = [] inside clearHistory() in 601dc4b. Without this, stale node IDs from the previous diagram could corrupt selection restoration on the first undo after a refresh() + clearHistory() call.

Tests — noted. The existing Playwright test suite for operation history would be the right place; happy to add a test case if that would help move this forward.

Tests verify: - Undo cannot revert into a pre-refresh diagram after clearHistory() - Operations performed after clearHistory() are themselves undoable/redoable - The first undo baseline is the refreshed diagram state, not a prior one

SSShooter

Thanks for your contribution! This is indeed a design oversight, but a few changes are needed here.

SSShooter · 2026-03-11T02:13:30Z

src/plugin/operationHistory.ts

+    history = []
+    currentIndex = -1
+    current = mei.getData()
+    currentSelectedNodes = []


better use mei.clearSelection()

That's indeed better. Done.

SSShooter · 2026-03-11T02:22:31Z

tests/clear-history.spec.ts

If the test is failing, please remove it for now.

Oups...
The tests should pass now.

SSShooter

LGTM

DisciplinedSoftware added 2 commits March 10, 2026 00:59

feat: add clearHistory() to MindElixirInstance type declaration

e6e688b

Copilot AI review requested due to automatic review settings March 10, 2026 05:01

Copilot started reviewing on behalf of DisciplinedSoftware March 10, 2026 05:02 View session

gemini-code-assist bot reviewed Mar 10, 2026

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Copilot AI reviewed Mar 10, 2026

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DisciplinedSoftware added 2 commits March 10, 2026 01:09

test: add Playwright tests for clearHistory()

1e50bf0

Tests verify: - Undo cannot revert into a pre-refresh diagram after clearHistory() - Operations performed after clearHistory() are themselves undoable/redoable - The first undo baseline is the refreshed diagram state, not a prior one

SSShooter reviewed Mar 11, 2026

View reviewed changes

fix: use mei.clearSelection() in clearHistory and fix tests

90b0e0e

DisciplinedSoftware force-pushed the feat/clear-history branch from 8596e68 to 90b0e0e Compare March 11, 2026 05:20

SSShooter approved these changes Mar 11, 2026

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SSShooter merged commit 14ff39b into SSShooter:master Mar 11, 2026
1 check passed

DisciplinedSoftware deleted the feat/clear-history branch March 11, 2026 15:22

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DisciplinedSoftware commented Mar 10, 2026

Motivation

Changes

src/plugin/operationHistory.ts

src/types/index.ts

Usage

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Summary of Changes

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`src/plugin/operationHistory.ts`

`src/types/index.ts`