Add LangSmith tracing plugin for Temporal workflows

CLAUDE.md

@@ -0,0 +1,51 @@
+# CLAUDE.md — Temporal Python SDK
+
+## CI Pipeline
+
+CI is defined in `.github/workflows/ci.yml`. The main jobs are:
+
+### `build-lint-test` (matrix: Python 3.10/3.14 x multiple OS)
+1. `poe build-develop` — builds the Rust bridge via maturin
+2. `poe lint` — runs ALL of the following (defined in `pyproject.toml [tool.poe.tasks]`):
+   - `uv run ruff check --select I` — import sorting
+   - `uv run ruff format --check` — code formatting
+   - `uv run pyright` — type checking (whole repo)
+   - `uv run mypy --namespace-packages --check-untyped-defs .` — type checking (whole repo)
+   - `uv run basedpyright` — stricter type checking (whole repo, catches more than pyright)
+   - `uv run pydocstyle --ignore-decorators=overload` — docstring style
+3. `poe test` — runs `uv run pytest`
+4. Time-skipping tests (non-ARM only)
+
+### `test-latest-deps` (ubuntu, Python 3.13, upgraded deps)
+Same as above but with `uv lock --upgrade` first.
+
+### `features-tests`
+Runs the `temporalio/features` repo tests against this branch.
+
+## Before Pushing
+
+Always run the full lint suite locally before pushing:
+```
+uv run ruff check --select I
+uv run ruff format --check
+uv run pyright
+uv run mypy --namespace-packages --check-untyped-defs .
+uv run basedpyright
+uv run pydocstyle --ignore-decorators=overload
+```
+
+Or equivalently: `poe lint` (requires `poe build-develop` first).
+
+To auto-fix formatting: `poe format` (runs `ruff check --select I --fix` + `ruff format`).
+
+## Dev Commands
+
+All commands use `uv run` prefix. Key poe tasks:
+- `poe build-develop` — build Rust bridge (required before lint/test)
+- `poe format` — auto-fix formatting
+- `poe lint` — run all linters
+- `poe test` — run pytest
+
+## Branch Naming
+
+Temporal convention: prepend `maplexu/` to branch names.

pyproject.toml

@@ -64,6 +64,7 @@ dev = [
   "openinference-instrumentation-google-adk>=0.1.8",
   "googleapis-common-protos==1.70.0",
   "pytest-rerunfailures>=16.1",
+  "langsmith>=0.7.17",
 ]
 
 [tool.poe.tasks]

temporalio/contrib/langsmith/__init__.py

@@ -0,0 +1,14 @@
+"""LangSmith integration for Temporal SDK.
+
+This package provides LangSmith tracing integration for Temporal workflows,
+activities, and other operations. It includes automatic run creation and
+context propagation for distributed tracing in LangSmith.
+"""
+
+from temporalio.contrib.langsmith._interceptor import LangSmithInterceptor
+from temporalio.contrib.langsmith._plugin import LangSmithPlugin
+
+__all__ = [
+    "LangSmithInterceptor",
+    "LangSmithPlugin",
+]