fix: replace direct state mutation in editor with proper store action

[andeplane]

Fixes #300

Problem

Edit.tsx was directly mutating file.content on the simulation object in the store:

const file = simulation?.files.find(...);
if (file) {
  file.content = newValue; // ← bypasses easy-peasy
}

This breaks easy-peasy's immutability contract, skips React re-renders for components observing simulation.files, and is inconsistent with the rest of the codebase.

Fix

• Added updateFileContent({ fileName, content }) action to SimulationModel that updates simulation.files immutably via .map()
• Edit.tsx now dispatches this action via useStoreActions
• Editor reads file content from simulation.files (the real source of truth) rather than the stale selectedFile reference

[gemini-code-assist]

Summary of Changes

Hello @andeplane, 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 resolves an issue where the editor component was directly modifying the application's state, bypassing the established state management patterns. The changes refactor the file content update mechanism to leverage a dedicated store action, ensuring all state modifications are handled consistently and immutably. This enhancement improves data integrity, predictability, and optimizes React's rendering efficiency by preventing stale data issues.

Highlights

• State Management Consistency: Replaced direct mutation of file.content within Edit.tsx with a proper easy-peasy store action, ensuring all state updates adhere to the immutability contract.
• New Store Action: Introduced a new updateFileContent action in src/store/simulation.ts to handle file content updates immutably, using a .map() operation to create a new array of files.
• Editor Data Source: Modified the editor in Edit.tsx to read the current file content directly from the simulation.files state, ensuring it always reflects the true source of truth and triggers correct React re-renders.

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Changelog

• src/containers/Edit.tsx
  • Refactored file content updates to dispatch the updateFileContent action via useStoreActions.
• src/store/simulation.ts
  • Added updateFileContent action to immutably update file content within the simulation state.

Activity

• No human activity has been recorded on this pull request yet.

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[gemini-code-assist]

Code Review

This pull request correctly addresses a critical issue of direct state mutation by introducing a proper easy-peasy action for updating file content. The changes ensure immutability, which fixes potential rendering bugs and aligns with best practices for state management. The implementation is clean and effectively resolves the problem described.

[gemini-code-assist]

The current logic for finding currentFile uses optional chaining (?.) inside the .find() callback. If selectedFile is null or undefined, this will result in searching for a file where fileName is undefined, which is likely not the intended behavior and could lead to subtle bugs if a file without a name exists.

A more robust approach is to check for selectedFile's existence before accessing its fileName property within the predicate. This makes the logic clearer and safer.

  const currentFile =
    simulation?.files.find(
      (file) => selectedFile && file.fileName === selectedFile.fileName,
    ) ?? selectedFile;

[andeplane]

/gemini review

[gemini-code-assist]

Code Review

This pull request correctly fixes a direct state mutation bug in Edit.tsx by introducing a proper updateFileContent action in the easy-peasy store. The change ensures state updates are immutable, which fixes potential rendering issues. The implementation is clean and effectively resolves the problem. I've added one suggestion for a potential future refactoring to further improve state management consistency.

[gemini-code-assist]

This logic to find the currentFile is a good workaround for the fact that selectedFile (from state.app) can become stale after its content is updated in state.simulation. However, this indicates a potential design improvement.

To ensure a single source of truth and improve maintainability, consider refactoring the app state to store only the selectedFile.fileName. The Edit component could then always derive the full currentFile object from state.simulation.simulation.files.

This would eliminate the need for this workaround and make the state management more robust. Here's a conceptual example:

// In your component:
const selectedFileName = useStoreState((state) => state.app.selectedFileName); // Assuming app state stores only the name
const files = useStoreState((state) => state.simulation.simulation?.files);
const currentFile = files?.find((file) => file.fileName === selectedFileName);

// ... use currentFile

This is a suggestion for future improvement and may be out of scope for the current fix.

[andeplane]

Addressed Gemini review: fixed the currentFile lookup to guard against selectedFile being null/undefined. Changed file.fileName === selectedFile?.fileName to selectedFile && file.fileName === selectedFile.fileName inside the .find() predicate, making the intent explicit and avoiding a subtle bug where a file without a name could match.