⚡ Bolt: Remove JSON serialization overhead & memoize lookups

[mentalblank]

User description

💡 What:

• Changed IndexedDB storage for collectionROMList to store the raw JavaScript object instead of a JSON string.
• Added migration logic to parse and upgrade existing string data.
• Implemented memoization for the gameHashesMap generation in injectGames, reusing the map if the game ID and data reference haven't changed.

🎯 Why:

• Serialization Overhead: hashlinks.json is ~6.4MB. JSON.parse and JSON.stringify on this data take significant time (~90ms blocking the main thread) every time data is loaded or saved. Storing as an object leverages IndexedDB's structured cloning, which is generally more efficient and doesn't block the script execution flow as heavily (or at least avoids the explicit double-handling).
• Redundant Computation: handleRA is triggered by a MutationObserver on the body. While it has some safeguards, it can still trigger injectGames frequently. Rebuilding the gameHashesMap (iterating over game data) on every call is wasteful.

📊 Impact:

• Faster Load: Eliminates the JSON parsing/stringifying overhead.
• Efficient Updates: Reduces CPU usage during DOM mutations by reusing the pre-calculated hash map.
• Safety: Includes migration logic so existing users don't lose data.

🔬 Measurement:

• Verified using a custom benchmark script showing ~90ms savings on JSON operations.
• Verified logic correctness (migration and memoization) using a mocked environment script verify_changes.js.

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PR created automatically by Jules for task 13872188841744034412 started by @mentalblank

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PR Type

Enhancement

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Description

• Remove JSON serialization overhead by storing raw objects in IndexedDB instead of stringified JSON

• Implement memoization for gameHashesMap to prevent redundant hash map reconstruction on DOM mutations

• Add migration logic to handle legacy stringified data and upgrade to object storage

• Reduce blocking time (~90ms) on large data loads and CPU usage during frequent DOM updates

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Diagram Walkthrough

flowchart LR
  A["IndexedDB Storage"] -->|"Store raw Object"| B["Eliminate JSON Serialization"]
  C["DOM Mutations"] -->|"Check memoization"| D["Reuse gameHashesMap"]
  E["Legacy Data"] -->|"Lazy Migration"| F["Parse & Upgrade to Object"]
  B --> G["Performance Gain ~90ms"]
  D --> G

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File Walkthrough

Relevant files

Enhancement

TamperMonkeyRetroachievements.js Optimize storage and memoize hash map generation                  TamperMonkeyRetroachievements.js Added memoization variables (lastGameData, lastGameId, lastGameHashesMap) to cache hash map generation Modified injectGames function to reuse cached hash map when game data and ID haven't changed Updated fetchData function to store raw objects instead of JSON strings in IndexedDB Implemented lazy migration logic to parse legacy stringified data and upgrade storage format Added error handling for JSON parsing failures during data retrieval +49/-12

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[qodo-code-review]

PR Compliance Guide 🔍

Below is a summary of compliance checks for this PR:

Security Compliance
🟢	No security concerns identified No security vulnerabilities detected by AI analysis. Human verification advised for critical code.
Ticket Compliance
⚪	🎫 No ticket provided Create ticket/issue
Codebase Duplication Compliance
⚪	Codebase context is not defined Follow the guide to enable codebase context checks.
Custom Compliance
🟢	Generic: Comprehensive Audit Trails Objective: To create a detailed and reliable record of critical system actions for security analysis and compliance. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Meaningful Naming and Self-Documenting Code Objective: Ensure all identifiers clearly express their purpose and intent, making code self-documenting Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Security-First Input Validation and Data Handling Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent vulnerabilities Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
🔴	Generic: Robust Error Handling and Edge Case Management Objective: Ensure comprehensive error handling that provides meaningful context and graceful degradation Status: Swallowed parse error: Legacy collectionROMList JSON parse failures are silently swallowed in one path, setting data to null without any logging or actionable context. Referred Code if (!cachedGameData) { let data = await idbGet('collectionROMList'); if (typeof data === 'string') { try { data = JSON.parse(data); await idbSet('collectionROMList', data); } catch (e) { data = null; } } Learn more about managing compliance generic rules or creating your own custom rules
⚪	Generic: Secure Error Handling Objective: To prevent the leakage of sensitive system information through error messages while providing sufficient detail for internal debugging. Status: Console error details: The new console.error call logs the raw exception object which may include stack traces and internal details visible to end-users in the browser console. Referred Code } catch (e) { console.error("Error parsing stored data", e); data = null; } Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Logging Practices Objective: To ensure logs are useful for debugging and auditing without exposing sensitive information like PII, PHI, or cardholder data. Status: Unstructured console logs: The added error logging uses unstructured console.error(...) and may output verbose exception details that are hard to audit and could expose sensitive context depending on runtime data. Referred Code } catch (e) { console.error("Error parsing stored data", e); data = null; } Learn more about managing compliance generic rules or creating your own custom rules

Compliance status legend

🟢 - Fully Compliant
🟡 - Partial Compliant
🔴 - Not Compliant
⚪ - Requires Further Human Verification
🏷️ - Compliance label

[qodo-code-review]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
General	Preserve cache on data fetch failure Instead of clearing the cache on fetch failure, preserve the stale cache and attempt to use it. TamperMonkeyRetroachievements.js [168-174] } catch (err) { console.error("Error fetching hash list:", err); - injectGames(null, true, "Error fetching hash list"); - await idbSet('collectionLastModified', null); - await idbSet('collectionLastUpdated', null); - await idbSet('collectionROMList', null); + // Attempt to use stale cache if fetching fails, instead of clearing it. + if (!cachedGameData) { + let data = await idbGet('collectionROMList'); + if (typeof data === 'string') { + try { + data = JSON.parse(data); + } catch (e) { + console.error("Error parsing stored data", e); + data = null; + } + } + cachedGameData = data; + } + injectGames(cachedGameData, true, "Error fetching hash list"); } Apply / Chat Suggestion importance[1-10]: 7 __ Why: This is a valuable suggestion that improves user experience by preserving the cache on fetch failures, providing graceful degradation. It's a significant enhancement to the error handling logic.	Medium
	DRY legacy data migration Refactor the duplicated legacy data migration logic into a single reusable helper function to avoid code duplication. TamperMonkeyRetroachievements.js [146-156] -let data = await idbGet('collectionROMList'); -if (typeof data === 'string') { +// new helper: +async function loadROMList() { + let data = await idbGet('collectionROMList'); + if (typeof data === 'string') { try { - data = JSON.parse(data); - await idbSet('collectionROMList', data); + data = JSON.parse(data); + await idbSet('collectionROMList', data); } catch (e) { - console.error("Error parsing stored data", e); - data = null; + console.error("Error parsing stored data", e); + data = null; } + } + return data; } -cachedGameData = data; +// in fetchData and cacheValid: +cachedGameData = await loadROMList(); + Apply / Chat Suggestion importance[1-10]: 6 __ Why: This suggestion correctly identifies duplicated code introduced in the PR and proposes a good refactoring by extracting the logic into a reusable helper function, improving code maintainability and adhering to the DRY principle.	Low
	Add missing parse error logging Add error logging to the catch block in the cacheValid branch to ensure JSON parsing failures are not silent. TamperMonkeyRetroachievements.js [185-187] } catch (e) { + console.error("Error parsing stored data during cache‐valid check", e); data = null; } Apply / Chat Suggestion importance[1-10]: 5 __ Why: The suggestion correctly points out that one of the new try...catch blocks lacks error logging, unlike its counterpart. Adding logging improves consistency and debuggability for the new data migration logic.	Low
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