1.3.0

lite-bootstrap 1.3.0 — free-threaded Python support, orjson becomes opt-in

1.3.0 is a minor release. Backward compatible with 1.2.3, with one dependency
change (orjson moves from a mandatory core dependency to an opt-in extra).
It lands free-threaded CPython (3.13t/3.14t) support for core and most extras,
plus two import-safety fixes surfaced while verifying it.

Features

• Free-threaded CPython (3.13t/3.14t) support. lite-bootstrap is pure
  Python; the only thing that ever blocked it on a free-threaded interpreter
  was the mandatory orjson dependency (below). Core, logging, sentry,
  fastapi, and faststream (plus their -sentry/-logging/-metrics
  combos) now install and run on both 3.13t and 3.14t. litestar (+
  litestar-metrics) and fastmcp (+ fastmcp-metrics) land on 3.14t
  only — msgspec (litestar) and cffi (fastmcp, via cryptography) both
  gate free-threaded support to Python 3.14+ and fail to build from source on
  3.13t. The gRPC otl exporter (grpcio has no ft wheels — use the new
  otl-http extra instead) and pyroscope (pyroscope-io is abi3-only and
  unmaintained) remain unavailable on free-threaded builds pending upstream
  fixes. See
  architecture/free-threading.md for
  the full support matrix and planning/deferred.md for the
  ecosystem blockers.

• OTLP-http exporter: new opentelemetry_exporter_protocol config (grpc
  default | http) and an otl-http extra (no grpcio) so OTLP trace export
  works on free-threaded Python. otl now pulls
  opentelemetry-exporter-otlp-proto-grpc directly (was the opentelemetry-exporter-otlp
  meta); grpc behavior is unchanged.

• orjson is now an opt-in extra (lite-bootstrap[orjson]) instead of a
  mandatory core dependency — it shipped no free-threaded wheels and its build
  refuses to compile under a free-threaded interpreter, which meant nothing,
  not even the pure extras, could install on ft before this change. The
  logging serializer falls back to the stdlib json accelerator when orjson
  is absent (byte-identical output for JSON-native values; ~2-5x slower;
  non-JSON-native types in log extra, e.g. datetime/UUID, render via repr
  instead of orjson's native encoding). Add [orjson] to keep the fast path
  on a standard (GIL) build. If your code relied on import lite_bootstrap
  pulling orjson in transitively, depend on orjson directly.

Bug fixes

• import_checker's dotted find_spec checks no longer crash on an
  incomplete namespace. find_spec imports a dotted name's parent package
  first, so a present-but-incomplete opentelemetry install (e.g.
  opentelemetry-api without opentelemetry-instrumentation) previously
  raised ModuleNotFoundError instead of returning False, crashing import lite_bootstrap. Affected dotted checks now go through a
  ModuleNotFoundError-safe helper.
• The gRPC OTLP exporter is no longer imported unconditionally.
  opentelemetry_instrument.py used to import
  opentelemetry.exporter.otlp.proto.grpc.trace_exporter whenever bare
  opentelemetry-api resolved, crashing import lite_bootstrap in any
  environment with opentelemetry-api present but the exporter package
  absent (e.g. lite-bootstrap[fastmcp], which pulls in bare
  opentelemetry-api transitively). The exporter import — and its use in
  bootstrap() — now sit behind their own is_otlp_grpc_exporter_installed
  guard. When opentelemetry_endpoint is set but the selected exporter package
  is absent, bootstrap() emits an InstrumentDependencyMissingWarning naming
  the extra to install ([otl] for gRPC, [otl-http] for HTTP); see
  architecture/instruments.md.
• The OpenTelemetry instrument no longer assumes the SDK is present when only
  the API is. is_opentelemetry_installed (find_spec("opentelemetry")) is
  true with just opentelemetry-api, but the instrument imports
  opentelemetry.sdk.* — a separate distribution. An api-only environment
  (e.g. lite-bootstrap[fastmcp]) therefore still crashed at the sdk import
  even after the exporter guard above. A new is_opentelemetry_sdk_installed
  flag gates the sdk imports, and check_dependencies() requires both the api
  and the sdk. With all three fixes, lite-bootstrap[fastmcp] imports and runs
  on free-threaded 3.14t.

These bugs are not ft-specific — they affect any environment with a partial
opentelemetry stack — but ft verification work is what surfaced them.

Backwards compatibility

Fully backward compatible with 1.2.3 at the API level. The one dependency
change is the orjson move to opt-in described above; everything that imports
or configures lite-bootstrap continues to work unchanged on a standard (GIL)
build once orjson is installed (directly, or via the [orjson] extra).

References

• Design bundle: planning/changes/2026-07-18.01-free-threaded-python-support.md,
  planning/changes/2026-07-19.01-fix-otel-api-sdk-conflation.md,
  planning/changes/2026-07-19.02-otlp-http-exporter.md.