fix(undo-redo): eviction policy to not have unbounded undo-redo stacks

[icecrasher321]

Summary

Must evict undo-redo stacks to 5 most recent edited workflows.

Type of Change

• Bug fix

Testing

Tested manually

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Preview	Comments	Updated (UTC)
docs	Skipped			Nov 20, 2025 8:08pm

[greptile-apps]

Greptile Overview

Greptile Summary

Implements LRU (Least Recently Used) eviction policy for undo-redo stacks to prevent unbounded memory growth in localStorage.

Key changes:

• Added MAX_STACKS constant (5) to limit number of workflow undo-redo stacks
• Added lastUpdated timestamp tracking to each stack for LRU eviction
• Implemented eviction logic that removes the oldest stack when creating a 6th stack
• Added safeStorageAdapter to gracefully handle localStorage QuotaExceededError
• Updated all stack operations (push, undo, redo) to maintain lastUpdated timestamps

The implementation correctly handles edge cases like existing stacks without lastUpdated (defaults to 0, evicted first) and maintains backward compatibility.

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• the LRU eviction logic is correctly implemented (evicts only when creating a new stack beyond MAX_STACKS limit), localStorage error handling is robust, backward compatibility is maintained with default timestamp of 0 for old stacks
• No files require special attention

Important Files Changed

File Analysis

Filename	Score	Overview
apps/sim/stores/undo-redo/store.ts	5/5	implemented LRU eviction policy for undo-redo stacks (max 5 workflows), added safe localStorage adapter to handle quota errors
apps/sim/stores/undo-redo/types.ts	5/5	added optional lastUpdated timestamp field to track most recently edited workflows for eviction

Sequence Diagram

sequenceDiagram
    participant User
    participant Store as UndoRedoStore
    participant Storage as safeStorageAdapter
    participant LS as localStorage

    User->>Store: push(workflowId, userId, entry)
    Store->>Store: Check if stackKeys.length >= MAX_STACKS
    alt Creating new stack when at limit
        Store->>Store: Find oldest stack by lastUpdated
        Store->>Store: Delete oldest stack
    end
    Store->>Store: Update/create stack with entry
    Store->>Store: Set lastUpdated = Date.now()
    Store->>Storage: setItem(state)
    alt localStorage has space
        Storage->>LS: localStorage.setItem()
    else QuotaExceededError
        Storage->>Storage: Log warning, continue
    end
    
    User->>Store: undo/redo operation
    Store->>Store: Update lastUpdated = Date.now()
    Store->>Storage: setItem(state)
    Storage->>LS: localStorage.setItem()

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[greptile-apps]

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