New Export Version

Cut a new game export format version. This creates a standalone schema, migration module, and updates all references.

Background

Each export version has its own schema file (src/magebench/game/game-export-vN.schema.json). In this repo, export migrations live in the single module src/magebench/game/game_export_migrations.py, and raw export file I/O lives in src/magebench/game/game_exports.py.

Key files:

• src/magebench/game/game-export-v*.schema.json — per-version JSON Schemas
• src/magebench/game/game_export_migrations.py — current/legacy version constants and normalization helpers
• src/magebench/game/game_exports.py — raw export load/write helpers used by scripts and tests
• src/magebench/game/export_game.py — export producer (sets version, computes new fields)
• tests/test_game_export_migrations.py — roundtrip migration tests
• tests/test_export_schema.py — schema validation tests

Step 1: Determine what's changing

Ask the user what fields are being added, removed, or modified. Determine:

• The current version number N (check the "version" line in src/magebench/game/export_game.py)
• What new fields to add and their JSON Schema types
• Whether the up() migration needs external data or is purely derived from existing fields
• Whether the down() migration is lossless (can we reconstruct N from N+1?)

Before deciding on a version bump for a semantics-only fix, check whether the latest typed loaders (load_game_export, load_built_game_export) are used directly against committed exports in tests or scripts. If they only accept the newest version, a code-only version bump can break local consumers until the repo's game exports are migrated too. In that case, consider whether an in-place backfill on the existing version is the safer path.

Step 2: Create the new schema file

Copy src/magebench/game/game-export-vN.schema.json to src/magebench/game/game-export-v{N+1}.schema.json:

• Change "const": N to "const": N+1 in the version property
• Update $id, title, description to reference v{N+1}
• Add new fields to properties
• Add new $defs if needed

Step 3: Extend the migration module

Add vN <-> v{N+1} support to src/magebench/game/game_export_migrations.py:

"""Migration: vN -> v{N+1} (description of what changes)."""

SOURCE_VERSION = N
TARGET_VERSION = N + 1

def up(data: dict) -> dict:
    """Migrate from vN to v{N+1}."""
    assert data["version"] == N, f"Expected vN, got v{data['version']}"
    # Add new fields here
    data["version"] = N + 1
    return data

def down(data: dict) -> dict:
    """Migrate from v{N+1} to vN."""
    assert data["version"] == N + 1, f"Expected v{N+1}, got v{data['version']}"
    # Remove new fields here
    data["version"] = N
    return data

The migration must satisfy: down(up(game)) == game for all exported games.

Step 4: Update src/magebench/game/export_game.py

1. Change "version": N to "version": N+1 in build_export()
2. Add computation for new fields in build_export()
3. Update _validate_export(): change version == N to version == N+1
4. Update the comment referencing the schema filename

Step 5: Update schema references

These files reference the schema filename and need updating:

• Makefile (regen-schema-types and verify-schema-types targets) → game-export-v{N+1}.schema.json
• .claude/hooks/enforce-agents-rules.py — no change needed (uses glob pattern)
• doc/export-schema.md — update prose reference if it mentions a specific version

Step 6: Regenerate TypeScript types

make regen-schema-types

Verify the generated types look correct in website/src/types/game-export.d.ts.

Step 7: Add tests

In tests/test_export_schema.py, add:

• test_v{N+1}_schema_is_valid — validates the new schema structure
• test_v{N+1}_schema_accepts_v{N+1} — minimal valid export passes
• test_v{N+1}_schema_rejects_vN — old version is rejected

In tests/test_game_export_migrations.py, add migration tests:

• test_vN_to_v{N+1}_up_adds_fields — verify up() adds the right fields
• test_v{N+1}_to_vN_down_removes_fields — verify down() strips them
• test_round_trip_preserves_vN_structure — down(up(game)) == game

When raw-export helpers are intentionally schema-light (for example load_raw_game_export() tests), make the migration functions tolerant of partial payloads. Only assert on version and transform optional sections when they are present.

Step 8: Run checks

make check

All lint, typecheck, and tests must pass before proceeding.

Step 9: Create the PR (usually code only — data migration optional)

Default to a code-only PR. Game migrations touch hundreds of JSON files and GitHub cannot render large diffs. If the issue explicitly asks for a bounded in-repo migration (for example one season only), migrate only that slice and file a follow-up issue for the remaining historical exports.

1. Create the PR with the code changes (schema, migration module, export_game.py, tests, docs, TypeScript types).
2. If you did not migrate all committed exports, note the remaining migration scope in the PR description and file a follow-up issue.

Step 10: Follow-up migration

This repo does not currently have a generic export migration runner. For bounded migrations, use src/magebench/game/game_exports.py helpers (load_raw_game_export() / write_raw_game_export()) or add a one-off script in the PR. Verify the migrated files with make check.