Function setEntry

src/services/SessionMemory/multiStore.ts:162–198

(store: string, key: string, value: string)

/** Write an entry to a store. Creates the store dir if needed. */
export function setEntry(store: string, key: string, value: string): void {
  validateStoreName(store)
  validateKey(key)

  // D2: Guard against unbounded value sizes (1 MB limit).
  // File-fallback vault is not designed for large data blobs.
  const byteLength = Buffer.byteLength(value, 'utf8')
  if (byteLength > MAX_VALUE_BYTES) {
    throw new Error(
      `Entry value too large: ${byteLength} bytes exceeds the 1 MB limit. ` +
        'Use external storage for large data.',
    )
  }

  const storeDir = getStoreDir(store)
  if (!existsSync(storeDir)) {
    mkdirSync(storeDir, { recursive: true })
  }
  const entryPath = getEntryPath(store, key)

  // C2: Atomic write — write to a .tmp file then rename.
  // On POSIX, rename(2) is atomic; on Windows it is best-effort but safe.
  // This prevents half-written files on crash mid-write.
  const tmpPath = join(storeDir, `.${randomBytes(8).toString('hex')}.tmp`)
  try {
    writeFileSync(tmpPath, value, 'utf8')
    renameSync(tmpPath, entryPath)
  } catch (err) {
    // Clean up tmp file on error
    try {
      rmSync(tmpPath, { force: true })
    } catch {
      /* ignore cleanup error */
    }
    throw err
  }
}

/** Read an entry from a store. Returns null if not found. */
export function getEntry(store: string, key: string): string | null {