Reversible Apply & Restoration

One of the greatest fears developers face when optimizing quality settings is: “What if these changes break something and we can’t remember the original values?”

DeviceFit eliminates this risk through durable, cryptographically-hashed change journaling (ChangeJournalService.cs).

Candidate Selected ──> Calculate SHA256 ──> Write Journal Entry ──> Apply Settings ──> Revert Anytime (1-Click)

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How the Change Journal Works

When you click Apply Reviewed Config in the Experiment Desk:

1. Pre-Apply Hash Calculation: DeviceFit reads the target asset file on disk (such as UniversalRenderPipelineGlobalSettings.asset or a texture meta file) and computes its SHA256 checksum.
2. Journal Persistence: A new record is appended to Library/DeviceFit/ChangeJournal.json:

   {
     "changeId": "CHG-20261022-094120",
     "timestamp": "2026-10-22T09:41:20Z",
     "targetAssetPath": "Assets/Settings/URP-High.asset",
     "preApplySha256": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
     "modifiedProperties": [
       { "name": "shadowDistance", "oldValue": 150.0, "newValue": 80.0 },
       { "name": "cascadeCount", "oldValue": 4, "newValue": 2 }
     ],
     "status": "APPLIED"
   }
   

3. In-Place Modification: Settings are written to the asset using serialized object transactions, followed by AssetDatabase.SaveAssets().

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Source Conflict Detection (DF-T06)

What happens if an artist or level designer modifies the URP Asset after DeviceFit applied a candidate setting?

In DF-T06_SourceConflict_BlocksBlindOverwrite, when you click Restore:

1. DeviceFit re-computes the current SHA256 checksum of the target asset on disk.
2. If the current hash does not match either the preApplySha256 or the post-apply state, DeviceFit detects an external modification conflict.
3. Blind overwrite is blocked, and the Applied Changes Window prompts the user with an actionable diff: [Conflict] Asset modified externally by user. Restore blocked to prevent data loss. [Force Revert] [Cancel]

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Crash & Interrupt Safety (DF-T07)

If Unity crashes or domain reload interrupts a multi-step apply operation:

• The journal status remains PENDING_VERIFICATION.
• Upon next editor launch, the journal detects the incomplete operation and offers safe automated rollback to the pre-apply state.