Merge branch 'mai/knuth/phase15-tags-management-unify' fix

db/migrate.go

@@ -16,10 +16,40 @@ var migrations embed.FS
 // EmbeddedMigrations exposes the raw embedded FS for tests.
 var EmbeddedMigrations = migrations
 
-// ApplyMigrations runs every embedded migration file in lexicographic order.
-// Idempotent because each migration is written as CREATE ... IF NOT EXISTS /
-// CREATE OR REPLACE / ON CONFLICT DO NOTHING.
+// ApplyMigrations runs every embedded migration that has not yet been
+// recorded in projax.schema_migrations. Migrations are applied in lexicographic
+// filename order; each successful apply inserts a row in schema_migrations so
+// subsequent boots short-circuit without re-running. This lets later
+// migrations destructively drop columns earlier ones created — historical
+// idempotency-on-re-run is no longer required.
 func ApplyMigrations(ctx context.Context, pool *pgxpool.Pool) error {
+	// Bootstrap the tracker. Lives in the projax schema so it shares grants
+	// with the rest of the surface. CREATE SCHEMA IF NOT EXISTS would fail
+	// without database-level CREATE; the tracker only creates within a
+	// schema we already own.
+	if _, err := pool.Exec(ctx, `
+		create table if not exists projax.schema_migrations (
+			name        text primary key,
+			applied_at  timestamptz not null default now()
+		)`); err != nil {
+		return fmt.Errorf("ensure schema_migrations: %w", err)
+	}
+
+	applied := map[string]struct{}{}
+	rows, err := pool.Query(ctx, `select name from projax.schema_migrations`)
+	if err != nil {
+		return fmt.Errorf("read applied migrations: %w", err)
+	}
+	for rows.Next() {
+		var n string
+		if err := rows.Scan(&n); err != nil {
+			rows.Close()
+			return fmt.Errorf("scan applied: %w", err)
+		}
+		applied[n] = struct{}{}
+	}
+	rows.Close()
+
 	entries, err := migrations.ReadDir("migrations")
 	if err != nil {
 		return fmt.Errorf("read migrations dir: %w", err)
@@ -34,6 +64,9 @@ func ApplyMigrations(ctx context.Context, pool *pgxpool.Pool) error {
 	sort.Strings(names)
 
 	for _, name := range names {
+		if _, ok := applied[name]; ok {
+			continue
+		}
 		body, err := migrations.ReadFile("migrations/" + name)
 		if err != nil {
 			return fmt.Errorf("read %s: %w", name, err)
@@ -41,6 +74,12 @@ func ApplyMigrations(ctx context.Context, pool *pgxpool.Pool) error {
 		if _, err := pool.Exec(ctx, string(body)); err != nil {
 			return fmt.Errorf("apply %s: %w", name, err)
 		}
+		if _, err := pool.Exec(ctx,
+			`insert into projax.schema_migrations (name) values ($1) on conflict (name) do nothing`,
+			name,
+		); err != nil {
+			return fmt.Errorf("record applied %s: %w", name, err)
+		}
 	}
 	return nil
 }

db/migrate_test.go

@@ -58,11 +58,13 @@ func TestMigrationsAreIdempotent(t *testing.T) {
 	}
 
 	var n int
-	if err := pool.QueryRow(ctx, `select count(*) from projax.items where 'area' = any(kind) and parent_id is null`).Scan(&n); err != nil {
-		t.Fatalf("count areas: %v", err)
+	if err := pool.QueryRow(ctx,
+		`select count(*) from projax.items where cardinality(parent_ids) = 0`,
+	).Scan(&n); err != nil {
+		t.Fatalf("count roots: %v", err)
 	}
 	if n < 7 {
-		t.Fatalf("expected at least 7 seeded areas, got %d", n)
+		t.Fatalf("expected at least 7 seeded roots, got %d", n)
 	}
 }