Function configureConnection

src/db/index.ts:30–45

* Apply connection-level PRAGMAs. Shared by `initialize` and `open` so the two * paths can't drift. * * `busy_timeout` is set FIRST, before any pragma that might touch the database * file (notably `journal_mode`). If another process holds a write lock at open * time, the later pragmas — and the

(db: SqliteDatabase)

 * (e.g. the git-hook `codegraph sync` running while the MCP server writes).
 */
function configureConnection(db: SqliteDatabase): void {
  db.pragma('busy_timeout = 5000');      // MUST be first — see above
  db.pragma('foreign_keys = ON');
  db.pragma('journal_mode = WAL');       // node:sqlite supports WAL on every platform
  db.pragma('synchronous = NORMAL');     // safe with WAL mode
  db.pragma('cache_size = -64000');      // 64 MB page cache
  db.pragma('temp_store = MEMORY');      // temp tables in memory
  db.pragma('mmap_size = 268435456');    // 256 MB memory-mapped I/O
  // Without a journal_size_limit the -wal file never shrinks below its
  // high-water mark while a connection lives: checkpoints fold frames back but
  // leave the file at full size, so one giant deferred-sync WAL stays giant
  // forever. With the limit set, any checkpoint that resets the WAL truncates
  // the file back down. Killed-process leftovers are handled separately by
  // healOversizedWal() at open. (#1431)
  db.pragma(`journal_size_limit = ${WAL_HEAL_THRESHOLD_BYTES}`);
}

/**
 * WAL size past which `healOversizedWal` (run at every `open`) checkpoints and