feat(python): add typed metrics template package

.config/mise/tasks/weaver/test/_default

@@ -1,3 +1,3 @@
 #!/usr/bin/env bash
 #MISE description="Run every policy and template package test, and validate generated code"
-#MISE depends=["weaver:test:policies", "weaver:test:templates", "weaver:test:go", "weaver:test:rust", "weaver:test:typescript_effect", "weaver:test:typescript"]
+#MISE depends=["weaver:test:policies", "weaver:test:templates", "weaver:test:go", "weaver:test:rust", "weaver:test:typescript_effect", "weaver:test:typescript", "weaver:test:python"]

.config/mise/tasks/weaver/test/python

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+#MISE description="Type-check, lint, and run consumer tests against generated Python"
+set -euo pipefail
+exec ./buildscripts/check_python_output.sh

.github/workflows/checks.yml

@@ -41,6 +41,7 @@ jobs:
       - run: mise run weaver:test:rust
       - run: mise run weaver:test:typescript_effect
       - run: mise run weaver:test:typescript
+      - run: mise run weaver:test:python
 
   markdown:
     name: Markdown

AGENTS.md

@@ -38,6 +38,11 @@ Each template package includes:
 Generated Go must pass `gofmt`, `go build`, and `go vet`, which
 `mise run weaver:test:go` checks.
 
+Generated Python must pass `ruff format --check`, `ruff check`, and
+`mypy --strict`, and each case's `test_consumer.py` must pass, which
+`mise run weaver:test:python` checks against the pinned OpenTelemetry Python
+API and SDK.
+
 Generated Rust must pass formatting, consumer tests, and Clippy, which
 `mise run weaver:test:rust` checks against the pinned OpenTelemetry Rust API
 and SDK.

CONTRIBUTING.md

@@ -60,6 +60,13 @@ temporary crates and runs formatting, consumer tests, and Clippy. Put consumer
 tests in a case's `test.rs`, importing the generated crate as
 `generated_semconv`.
 
+For the Python package, `mise run weaver:test:python` runs formatting, lint,
+and `mypy --strict` over every expected module and runs each case's
+`test_consumer.py` with an SDK `InMemoryMetricReader`. Consumers import the
+generated package as `semconv`. Requirements are locked with hashes in
+`buildscripts/python/` and installed in a disposable virtual environment outside
+the checkout.
+
 For the TypeScript package, `mise run weaver:test:typescript` type-checks every
 expected module and runs each case's `consumer.test.ts` against the pinned
 OpenTelemetry JavaScript API and SDK. Consumers import `./metrics.ts`, may use

README.md

@@ -6,7 +6,7 @@ is versioned and released from this repository, ready to be referenced by tag.
 
 **The packages turn a semantic convention registry into code and keep that
 registry fit for generation.** Templates generate typed telemetry helpers, such
-as typed attribute values and signal helpers on the OpenTelemetry Go and
+as typed attribute values and signal helpers on the OpenTelemetry Go, Python and
 Rust APIs.
 Policies run during `weaver registry check` and reject conventions a template
 cannot render, before any code is written.
@@ -31,6 +31,7 @@ Templates live under [`templates`](templates) and policies under
 does and the params it accepts.
 
 - [Go code generation](templates/code/go/README.md)
+- [Python metrics](templates/code/python/README.md)
 - [Rust code generation](templates/code/rust/README.md)
 - [TypeScript metrics](templates/code/typescript/README.md)
 - [Effect TypeScript metrics](templates/code/typescript_effect/README.md)

buildscripts/check_python_output.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT="$(pwd)"
+PACKAGE_DIR="${ROOT}/templates/code/python"
+TOOLING_DIR="${ROOT}/buildscripts/python"
+WORK_DIR="$(mktemp -d "${TMPDIR:-/tmp}/weaver-python.XXXXXX")"
+trap 'rm -rf "${WORK_DIR}"' EXIT
+export PYTHONDONTWRITEBYTECODE=1
+
+for test_dir in "${PACKAGE_DIR}"/tests/*/; do
+  test_name="$(basename "${test_dir}")"
+  [[ -f "${test_dir}expected-error.txt" ]] && continue
+  if [[ ! -f "${test_dir}expected/__init__.py" ]]; then
+    echo "  FAIL: ${test_name} is missing expected/__init__.py."
+    exit 1
+  fi
+  if [[ ! -f "${test_dir}test_consumer.py" ]]; then
+    echo "  FAIL: ${test_name} is missing test_consumer.py."
+    exit 1
+  fi
+  mkdir -p "${WORK_DIR}/cases/${test_name}/semconv"
+  cp -R "${test_dir}expected/." "${WORK_DIR}/cases/${test_name}/semconv/"
+  cp "${test_dir}test_consumer.py" "${WORK_DIR}/cases/${test_name}/"
+done
+
+uv venv --quiet --python "$(command -v python)" "${WORK_DIR}/venv"
+uv pip install --quiet --python "${WORK_DIR}/venv/bin/python" --require-hashes --no-deps -r "${TOOLING_DIR}/requirements.txt"
+BIN="${WORK_DIR}/venv/bin"
+
+echo "-> Checking ruff format ..."
+"${BIN}/ruff" format --check --config "${TOOLING_DIR}/ruff.toml" "${WORK_DIR}/cases"
+echo "-> Checking ruff check ..."
+"${BIN}/ruff" check --no-cache --config "${TOOLING_DIR}/ruff.toml" "${WORK_DIR}/cases"
+
+shopt -s nullglob
+cases=("${WORK_DIR}"/cases/*/)
+if [[ ${#cases[@]} -eq 0 ]]; then
+  echo 'FAIL: no Python cases found'
+  exit 1
+fi
+for case_dir in "${cases[@]}"; do
+  echo "-> Checking Python [$(basename "${case_dir}")] ..."
+  (
+    cd "${case_dir}"
+    "${BIN}/mypy" --config-file "${TOOLING_DIR}/mypy.ini" --cache-dir "${WORK_DIR}/mypy-cache" semconv test_consumer.py
+    "${BIN}/python" -m pytest --quiet --disable-warnings -p no:cacheprovider test_consumer.py
+  )
+done

buildscripts/python/mypy.ini

@@ -0,0 +1,5 @@
+[mypy]
+python_version = 3.12
+strict = True
+warn_unused_ignores = True
+cache_dir = .mypy_cache

buildscripts/python/requirements.in

@@ -0,0 +1,6 @@
+# Regenerate requirements.txt with: mise exec -- uv pip compile --generate-hashes --python-version 3.12 --no-header -o requirements.txt requirements.in
+mypy==2.4.1
+opentelemetry-api==1.45.2
+opentelemetry-sdk==1.45.2
+pytest==9.2.0
+ruff==0.17.3