v0.5.0

[0.5.0] - 2026-03-16

Major feature release. Substantial surface added; several subtle
behavioral changes worth noting on upgrade.

Added

• Online backup API. XqliteNIF.backup/2 + restore/2 (one-shot),
  plus backup_with_progress/6 (page-by-page with progress messages to
  a PID, cancel-token support).
• Session extension. session_new, session_attach, session_changeset,
  session_delete, changeset_invert, changeset_concat,
  changeset_apply with conflict strategies (:omit, :replace,
  :abort).
• Incremental blob I/O. blob_open, blob_read, blob_write,
  blob_close. Read and write multi-GB column values without loading
  them into memory.
• Extension loading. enable_load_extension/2 and
  load_extension/2,3. Opt-in; disabled by default.
• Serialize / deserialize. serialize/1 captures the entire live
  database as a single binary byte-for-byte identical to its on-disk
  form; deserialize/2 loads it back.
• Log hook and update hook via raw enif_send. Per-connection
  update notifications as {:xqlite_update, action, db, table, rowid};
  global log hook as {:xqlite_log, code, message}.
• Type extension behaviour. Xqlite.TypeExtension for bidirectional
  Elixir↔SQLite conversion. Built-ins shipped for DateTime, Date,
  Time, NaiveDateTime.
• Xqlite.Result struct implementing the Table.Reader protocol —
  consumable directly by Explorer, Kino, VegaLite.
• XqliteNIF.transaction_status/1 — structured query of the
  current connection's transaction state.
• Read-only opens. open_readonly/1 and open_in_memory_readonly/1.
• Transaction modes. deferred, immediate, exclusive.
• Schema-prefixed PRAGMAs. :db_name option for PRAGMAs that accept
  a database name parameter.

Changed

• PRAGMA schema reworked from a keyword list to Xqlite.PragmaSpec
  structs. Public shape change for anyone introspecting PRAGMA
  metadata.
• PRAGMA SET now returns the echoed value instead of discarding it,
  matching the {:ok, echoed_value} shape of the rest of the API.
• XqliteNIF.close/1 eagerly releases the underlying SQLite
  connection rather than waiting for Elixir GC.
• rusqlite upgraded 0.38 → 0.39. UTF-8 errors now carry the column
  index of the offending value.

Fixed

• Stream finalization data race where sqlite3_finalize could run
  without the connection Mutex held — a BEAM-segfault-class bug.
• stream_fetch now holds the Mutex for the entire fetch loop (was
  dropping it between steps).
• TOCTOU race in the with_conn closed-flag check.
• Atom-table exhaustion protection: user input no longer becomes atoms
  unconditionally.
• SQL length overflow guard in stream_open.
• Integer-truncation guard for FFI bind calls.
• Identifier quoting: single quotes → double quotes for SQLite spec
  compliance.
• PRAGMA name validation against SQL injection (reject non-identifier
  PRAGMA names).
• PRAGMA validation catch-all for unknown names and corrected numeric
  ranges.
• Interruption detection, cancel ordering, and error-code mapping.