chore: gate pyo3 extension module behind optional feature

Author: tzanko-matev

.agents/tasks/2025/08/18-1208-tracer-trait

@@ -71,3 +71,8 @@ artefact, it will be used only for testing.
 
 Refer to the design-docs folder for the current planned design. Add/update files in the folder to match what was implemented in this task.
 
+
+--- FOLLOW UP TASK ---
+1. In codetracer-python-recorder/Cargo.toml, move pyo3’s extension-module feature to an optional crate feature and enable it only for release builds.
+2. Update Justfile (and CI scripts) to run cargo test --no-default-features so the test binary links with the Python C library.
+3. Add pyo3 with auto-initialize under [dev-dependencies] if tests require the interpreter to be initialized automatically.

.github/workflows/ci.yml

@@ -21,6 +21,8 @@ jobs:
           nix_path: nixpkgs=channel:nixos-25.05
           extra_nix_config: |
             experimental-features = nix-command flakes
+      - name: Run Rust tests
+        run: nix develop --command bash -lc 'cargo test --manifest-path codetracer-python-recorder/Cargo.toml --no-default-features'
       - name: Build Rust module and run tests via Nix
         run: nix develop --command bash -lc 'just venv ${{matrix.python-version}} dev test'
 

Justfile

@@ -32,9 +32,13 @@ dev:
     uv run --directory codetracer-python-recorder maturin develop --uv
 
 # Run unit tests of dev build
-test:
+test: cargo-test
     uv run --group dev --group test pytest
 
+# Run Rust unit tests without default features to link Python C library
+cargo-test:
+    cargo test --manifest-path codetracer-python-recorder/Cargo.toml --no-default-features
+
 # Run tests only on the pure recorder
 test-pure:
     uv run --group dev --group test pytest codetracer-pure-python-recorder

codetracer-python-recorder/Cargo.toml

@@ -10,6 +10,13 @@ repository = "https://github.com/metacraft-labs/codetracer-python-recorder"
 name = "codetracer_python_recorder"
 crate-type = ["cdylib"]
 
+[features]
+extension-module = ["pyo3/extension-module"]
+default = ["extension-module"]
+
 [dependencies]
-pyo3 = { version = "0.25.1", features = ["extension-module"] }
-runtime_tracing = "0.14.0"
+pyo3 = { version = "0.25.1" }
+runtime_tracing = "0.14.0"
+
+[dev-dependencies]
+pyo3 = { version = "0.25.1", features = ["auto-initialize"] }