The file cache in package_dependencies.jsonl is keyed on (name, version, python_version) only; if deps constraints for an integration change in TEST_SUITE_CONFIG, a subsequent run will return the previously-cached (now incorrect) resolved dependencies without re-running the pip dry-run, silently producing wrong transitive dependency pins.

In _has_free_threading_dependencies (populate_tox.py ~line 730), when a transitive dependency only ships as a source distribution, the code does:

package_release = wheel_filename.rstrip(".tar.gz")
dependency_name, dependency_version = package_release.split("-")

The unpack assumes exactly two parts. For any sdist whose package name contains a hyphen (e.g. azure-core-1.29.5.tar.gz, google-auth-2.x.y.tar.gz, typing-extensions-...tar.gz), split("-") yields ≥3 elements and raises ValueError: too many values to unpack (expected 2), aborting tox generation for that combination.

Use package_release.rsplit("-", 1) to split off only the version (PEP 440 versions never contain - in this context once the sdist filename is formed). Note also that rstrip(".tar.gz") is character-based and will over-strip filenames ending in characters from {., t, a, r, g, z} (e.g. foo-1.0.tar.gz → foo-1.0 ok, but foobar-1.0.tar.gz → foobar-1.0 also ok; however foo-1.2.tar.gz is fine while a name like boto3-... is fine — but the pattern is still fragile and should be removesuffix(".tar.gz")).

When _render_transitive_dependencies calls fetch_package_dependencies with a non-empty constraints tuple, _fetch_package_dependencies_from_cache ignores constraints in its key lookup, so a prior unconstrained disk-cache entry (e.g. one written by _has_free_threading_dependencies for the same (package, version, "3.14t") triple) is returned as-is, silently discarding the constraints and producing incorrect pinned transitive dependencies for that Python version.

When _render_transitive_dependencies raises DryRunFailed for a particular (release, python_version), the loop continues without appending to release.transitive_dependencies, but the release stays in test_releases and gets rendered into tox.ini with pins from whichever Python versions succeeded. The failure is only surfaced via a print() during generation, so the generated tox.ini carries no marker that pinning is partially missing for one Python version. Since this is a developer-run CI tooling script with visible stdout output (not runtime/production code), severity is low — consider either failing the run, or emitting a comment into the generated env so the gap is auditable after the fact.