refactor: dedupe INSERT SQL and DDL exec in migrate.ts

- Extract INSERT_MIGRATION_SQL constant; was repeated three times.
- Hoist db.exec(SCHEMA_MIGRATIONS_DDL) above the genesis-stamp branch
  so it is no longer duplicated in both arms of the if/else.
- Prepare insertRow once and reuse it for both genesis-stamping and
  the per-file insert in the apply loop.
- Simplify existence probe in stampMigration to SELECT 1 and drop the
  misleading MigrationRow cast (only existence was checked).

dist/migrate.js

@@ -11,6 +11,7 @@ const SCHEMA_MIGRATIONS_DDL = `
     applied_at INTEGER NOT NULL
   );
 `;
+const INSERT_MIGRATION_SQL = `INSERT INTO schema_migrations (version, name, checksum, applied_at) VALUES (?, ?, ?, ?)`;
 function sha256Hex(body) {
     return createHash('sha256').update(body).digest('hex');
 }
@@ -54,28 +55,24 @@ export function applyMigrations(db, migrationsDir, opts = {}) {
         return { applied: 0, pending: 0, alreadyApplied: 0, stamped: [] };
     }
     const schemaMigrationsExists = tableExists(db, 'schema_migrations');
-    const stamped = [];
     const genesisFile = files.find((f) => f.version === GENESIS_VERSION);
     const shouldStampGenesis = !schemaMigrationsExists &&
         genesisFile !== undefined &&
         (opts.stampGenesis === true || tableExists(db, probeTable));
+    db.exec(SCHEMA_MIGRATIONS_DDL);
+    const insertRow = db.prepare(INSERT_MIGRATION_SQL);
+    const stamped = [];
     if (shouldStampGenesis && genesisFile) {
-        db.exec(SCHEMA_MIGRATIONS_DDL);
         const reason = opts.stampGenesis
             ? 'stampGenesis option set'
             : `detected pre-existing '${probeTable}' table`;
         log(`WARN genesis-stamp: marked ${genesisFile.name} as applied without executing (${reason})`);
-        db.prepare(`INSERT INTO schema_migrations (version, name, checksum, applied_at) VALUES (?, ?, ?, ?)`).run(genesisFile.version, genesisFile.name, genesisFile.checksum, Date.now());
+        insertRow.run(genesisFile.version, genesisFile.name, genesisFile.checksum, Date.now());
         stamped.push(genesisFile.version);
     }
-    else {
-        db.exec(SCHEMA_MIGRATIONS_DDL);
-    }
-    const appliedRows = readAppliedRows(db);
-    const appliedByVersion = new Map(appliedRows.map((r) => [r.version, r]));
+    const appliedByVersion = new Map(readAppliedRows(db).map((r) => [r.version, r]));
     let applied = 0;
     let alreadyApplied = 0;
-    const insertRow = db.prepare(`INSERT INTO schema_migrations (version, name, checksum, applied_at) VALUES (?, ?, ?, ?)`);
     for (const file of files) {
         const existing = appliedByVersion.get(file.version);
         if (existing) {
@@ -103,11 +100,11 @@ export function stampMigration(db, migrationsDir, version) {
     }
     db.exec(SCHEMA_MIGRATIONS_DDL);
     const existing = db
-        .prepare(`SELECT version, name, checksum, applied_at FROM schema_migrations WHERE version = ?`)
+        .prepare(`SELECT 1 FROM schema_migrations WHERE version = ?`)
         .get(file.version);
     if (existing) {
         throw new Error(`migration already applied: ${file.name}`);
     }
-    db.prepare(`INSERT INTO schema_migrations (version, name, checksum, applied_at) VALUES (?, ?, ?, ?)`).run(file.version, file.name, file.checksum, Date.now());
+    db.prepare(INSERT_MIGRATION_SQL).run(file.version, file.name, file.checksum, Date.now());
     return file;
 }

src/migrate.ts

@@ -43,6 +43,8 @@ const SCHEMA_MIGRATIONS_DDL = `
   );
 `;
 
+const INSERT_MIGRATION_SQL = `INSERT INTO schema_migrations (version, name, checksum, applied_at) VALUES (?, ?, ?, ?)`;
+
 function sha256Hex(body: string): string {
   return createHash('sha256').update(body).digest('hex');
 }
@@ -97,38 +99,31 @@ export function applyMigrations(
   }
 
   const schemaMigrationsExists = tableExists(db, 'schema_migrations');
-  const stamped: string[] = [];
-
   const genesisFile = files.find((f) => f.version === GENESIS_VERSION);
   const shouldStampGenesis =
     !schemaMigrationsExists &&
     genesisFile !== undefined &&
     (opts.stampGenesis === true || tableExists(db, probeTable));
 
+  db.exec(SCHEMA_MIGRATIONS_DDL);
+  const insertRow = db.prepare(INSERT_MIGRATION_SQL);
+
+  const stamped: string[] = [];
   if (shouldStampGenesis && genesisFile) {
-    db.exec(SCHEMA_MIGRATIONS_DDL);
     const reason = opts.stampGenesis
       ? 'stampGenesis option set'
       : `detected pre-existing '${probeTable}' table`;
     log(
       `WARN genesis-stamp: marked ${genesisFile.name} as applied without executing (${reason})`,
     );
-    db.prepare(
-      `INSERT INTO schema_migrations (version, name, checksum, applied_at) VALUES (?, ?, ?, ?)`,
-    ).run(genesisFile.version, genesisFile.name, genesisFile.checksum, Date.now());
+    insertRow.run(genesisFile.version, genesisFile.name, genesisFile.checksum, Date.now());
     stamped.push(genesisFile.version);
-  } else {
-    db.exec(SCHEMA_MIGRATIONS_DDL);
   }
 
-  const appliedRows = readAppliedRows(db);
-  const appliedByVersion = new Map(appliedRows.map((r) => [r.version, r]));
+  const appliedByVersion = new Map(readAppliedRows(db).map((r) => [r.version, r]));
 
   let applied = 0;
   let alreadyApplied = 0;
-  const insertRow = db.prepare(
-    `INSERT INTO schema_migrations (version, name, checksum, applied_at) VALUES (?, ?, ?, ?)`,
-  );
 
   for (const file of files) {
     const existing = appliedByVersion.get(file.version);
@@ -166,15 +161,16 @@ export function stampMigration(
   }
   db.exec(SCHEMA_MIGRATIONS_DDL);
   const existing = db
-    .prepare(
-      `SELECT version, name, checksum, applied_at FROM schema_migrations WHERE version = ?`,
-    )
-    .get(file.version) as MigrationRow | undefined;
+    .prepare(`SELECT 1 FROM schema_migrations WHERE version = ?`)
+    .get(file.version);
   if (existing) {
     throw new Error(`migration already applied: ${file.name}`);
   }
-  db.prepare(
-    `INSERT INTO schema_migrations (version, name, checksum, applied_at) VALUES (?, ?, ?, ?)`,
-  ).run(file.version, file.name, file.checksum, Date.now());
+  db.prepare(INSERT_MIGRATION_SQL).run(
+    file.version,
+    file.name,
+    file.checksum,
+    Date.now(),
+  );
   return file;
 }