Use long for edit byte totals to avoid overflow

[dsarno]

Summary

• switch ApplyTextEdits to track UTF-8 byte counts with long
• wrap byte count accumulation in checked to guard against overflow

Testing

• pytest -q

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https://chatgpt.com/codex/tasks/task_e_68a1e82028f883279970e50b1fbf06e7

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[greptile-apps]

Greptile Summary

This PR addresses a potential integer overflow issue in the ApplyTextEdits method within the Unity MCP Bridge's script management system. The change modifies how UTF-8 byte counts are tracked during text editing operations by switching from a 32-bit int to a 64-bit long for the totalBytes variable and adding overflow protection with a checked block.

The modification is part of the ManageScript.cs file, which handles script editing operations in Unity's MCP Bridge. This bridge enables communication between Unity applications and Large Language Models via the Model Context Protocol. The ApplyTextEdits method processes text modifications and validates their size, making it critical for the system's text editing functionality.

The change integrates seamlessly with the existing codebase architecture. The method continues to function identically from an external perspective, but now handles edge cases more robustly. The long type provides a practically unlimited range for byte counting (9.2 × 10^18 vs 2.1 × 10^9 for int), while the checked block ensures any theoretical overflow would throw an OverflowException rather than silently wrapping to negative values.

Important Files Changed

File Changes

Filename	Score	Overview
UnityMcpBridge/Editor/Tools/ManageScript.cs	5/5	Changed totalBytes from int to long and added overflow protection with checked block

Confidence score: 5/5

• This PR is safe to merge with minimal risk
• Score reflects simple, defensive programming improvements with no behavioral changes
• No files require special attention

Sequence Diagram

sequenceDiagram
    participant User
    participant ManageScript
    participant FileSystem
    participant SHA256
    participant ValidationSystem
    participant RefreshDebounce
    participant AssetDatabase

    User->>ManageScript: "HandleCommand(apply_text_edits)"
    ManageScript->>FileSystem: "File.ReadAllText(fullPath)"
    FileSystem-->>ManageScript: "original content"
    
    ManageScript->>SHA256: "ComputeSha256(original)"
    SHA256-->>ManageScript: "currentSha"
    
    alt precondition check fails
        ManageScript-->>User: "Error: stale_file"
    end
    
    ManageScript->>ManageScript: "Convert edits to spans"
    ManageScript->>ManageScript: "Check totalBytes <= MaxEditPayloadBytes"
    
    alt payload too large
        ManageScript-->>User: "Error: too_large"
    end
    
    ManageScript->>ManageScript: "Sort spans descending by start"
    ManageScript->>ManageScript: "Check for overlapping edits"
    
    alt edits overlap
        ManageScript-->>User: "Error: Edits overlap"
    end
    
    ManageScript->>ManageScript: "Apply edits to working text"
    ManageScript->>ValidationSystem: "CheckBalancedDelimiters(working)"
    ValidationSystem-->>ManageScript: "validation result"
    
    alt unbalanced delimiters
        ManageScript-->>User: "Error: unbalanced_braces"
    end
    
    ManageScript->>SHA256: "ComputeSha256(working)"
    SHA256-->>ManageScript: "newSha"
    
    ManageScript->>FileSystem: "File.WriteAllText(tmp, working)"
    ManageScript->>FileSystem: "File.Replace(tmp, fullPath, backup)"
    FileSystem-->>ManageScript: "write complete"
    
    ManageScript->>RefreshDebounce: "ScheduleScriptRefresh(relativePath)"
    RefreshDebounce->>AssetDatabase: "ImportAsset(relPath)"
    
    ManageScript-->>User: "Success: Applied edits"

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