chore(Justfile): allow regenerating migrations by commit hash

Justfile

@@ -34,20 +34,33 @@ test:
 format:
     mix format
 
-
-regen-migrations migration_name:
-  #!/bin/bash
+# Usage:
+#   just regen-migrations migration_name [commit_hash]
+# If commit_hash is given, rollback & delete the migrations from that commit.
+# Otherwise, rollback & delete all untracked migrations.
+regen-migrations migration_name commit_hash='':
+  #!/usr/bin/env bash
   set -euo pipefail
-  # Get count of untracked migrations
-  N_MIGRATIONS=$(git ls-files --others priv/repo/migrations | wc -l)
-  # Rollback untracked migrations
-  mix ash_postgres.rollback -n $N_MIGRATIONS
-  # Delete untracked migrations and snapshots
-  git ls-files --others priv/repo/migrations | xargs rm
-  git ls-files --others priv/resource_snapshots | xargs rm
-  # Regenerate migrations
-  mix ash.codegen --name {{migration_name}}
-  # Run migrations if flag
-  if echo $* | grep -e "-m" -q; then
-    mix ash.migrate
+  # Pick migrations either from the given commit or untracked files
+  if [ -n "{{commit_hash}}" ]; then
+    echo "→ Rolling back migrations from commit {{commit_hash}}"
+    MIG_FILES=$(git show --name-only --pretty=format: "{{commit_hash}}" \
+                | grep -E "^priv/repo/migrations/|^priv/resource_snapshots")
+  else
+    echo "→ Rolling back all untracked migrations"
+    MIG_FILES=$(git ls-files --others priv/repo/migrations)
   fi
+
+  # Roll back in Ash
+  COUNT=$(echo "$MIG_FILES" | wc -l)
+  mix ash_postgres.rollback -n "$COUNT"
+
+  # Remove the migration files
+  echo removing $MIG_FILES
+  echo "$MIG_FILES" | xargs rm -f
+
+  # Also clean up any untracked resource snapshots
+  git ls-files --others priv/resource_snapshots | xargs rm -f
+
+  # Generate a fresh migration
+  mix ash.codegen --name "{{migration_name}}"