Fighting Game · Guides & deep dives

Mod Save Game Compatibility

data key, saved mod version, whether the reference is required for load, whether vanilla fallback data exists, and whether a migration is available.

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Task: TODOS.phase-72.72.14.2.12

V2 mod save game compatibility is a pre-disable gate for mod management flows. It detects whether disabling a mod would break save loading, warns before disable when fallback or migration paths exist, and blocks disable when a save depends on required mod-owned data with no safe replacement.

Policy#

FV2ModSaveGameCompatibilityPolicy is created by BuildDefaultModSaveGameCompatibilityPolicy and enables:

  • warning before disabling a mod referenced by saves
  • blocking required save references with no fallback or migration
  • allowing disable when vanilla fallback data exists
  • allowing disable after save migration
  • backup-before-disable actions
  • a deterministic issue cap

Save References#

FV2ModSaveGameReference records the mod id, save slot, entity id, asset path, data key, saved mod version, whether the reference is required for load, whether vanilla fallback data exists, and whether a migration is available.

Malformed disable requests and save references are blocking validation issues: the evaluator requires a target mod id and save slot before disable decisions can be trusted.

Disable Preflight#

EvaluateModSaveGameCompatibility compares pending disable mod ids with save references and returns an FV2ModSaveGameCompatibilityReport.

Required save references without a fallback or migration produce Blocker issues and actions to keep the mod enabled or block disable. Migratable references produce Warning issues plus backup and migration actions. Fallback references produce Warning issues plus backup and disable-with-warning actions.

The report exposes bSafeToDisable, bRequiresWarning, SaveReferencesEvaluated, warning/blocking counts, issues, and actions so mod browser, auto-update, and settings flows can warn before disable without duplicating save compatibility logic.

Verification#

Run:

bash
python3 V2/ue/Tools/check-v2-mod-save-game-compatibility.py
python3 -m json.tool V2/ue/Content/V2/Modding/ModSaveGameCompatibility_V2_Contract.json

The focused checker verifies runtime types, disable preflight behavior, required save-reference blockers, migration warnings, fallback warnings, backup actions, invalid-input validation, automation assertions, docs, CI/Horde wiring, and TODO evidence for 72.14.2.12.