schema-migration-safety

name	schema-migration-safety
description	Generate two-step rollout-safe Django migrations plus model-field patching using jig.

Schema Migration Safety (Jig)

Use this skill for backwards-compatible model field rollout.

Required Variables

• app_label
• model_name
• field_name
• field_type
• add_field_kwargs
• final_field_kwargs
• previous_migration
• add_migration_name
• finalize_migration_name
• backfill_value

Usage

jig run ${CLAUDE_SKILL_DIR}/recipe.yaml --vars '{
  "app_label": "core",
  "model_name": "Entity",
  "field_name": "classification",
  "field_type": "models.CharField",
  "add_field_kwargs": "max_length=20, null=True",
  "final_field_kwargs": "max_length=20",
  "previous_migration": "0007_auto_20260407_1200",
  "add_migration_name": "0008_add_entity_classification",
  "finalize_migration_name": "0009_enforce_entity_classification",
  "backfill_value": "\"standard\""
}'

Notes

• Migration 1 adds nullable field + backfill.
• Migration 2 enforces final constraints.
• model_file patching targets the rendered model_name class anchor directly.
• If jig fails, use rendered output from stderr and apply manually.