ci: the drift job checks an installed wheel, not just the source tree

.github/workflows/ci.yml

@@ -236,6 +236,25 @@ jobs:
         run: |
           uv sync --all-extras --group dev
           uv run pytest
+      - name: The wheel still imports against the re-resolved versions
+        # The other half of #103. The suite above runs from the source tree, so a
+        # packaging break that only shows in an *installed* wheel -- a subpackage
+        # dropped, or an extra whose new major moves a module the package imports
+        # at import time -- would not surface there. #101 was exactly that shape:
+        # `mcp>=1.2` resolved to 2.0.0 for anyone installing fresh,
+        # `mcp.server.fastmcp` had gone, and `grapharc[mcp]` was broken on
+        # arrival while every locked job stayed green.
+        #
+        # Same script the build job runs, pointed at a clean environment built
+        # from `pyproject.toml`'s ranges rather than from `uv.lock`.
+        run: |
+          uv build
+          uv venv --python 3.12 /tmp/driftcheck
+          uv pip install --python /tmp/driftcheck/bin/python "$(echo dist/*.whl)[all]"
+          cd /tmp
+          /tmp/driftcheck/bin/python "$GITHUB_WORKSPACE/scripts/wheel_import_walk.py" \
+            --source-tree "$GITHUB_WORKSPACE" --expect-prefix /tmp/driftcheck/
+          /tmp/driftcheck/bin/grapharc --version
       - name: Say so where someone will see it
         # A scheduled run reports to nobody. This repository has already paid
         # for that: `pages.yml` failed on two consecutive pushes and the
@@ -291,48 +310,16 @@ jobs:
         run: uvx twine check --strict dist/*
       - name: Wheel installs and imports in a clean environment
         # Runs from /tmp so an `import grapharc` cannot fall back to the
-        # checked-out source tree and pass for the wrong reason.
+        # checked-out source tree and pass for the wrong reason. The check is
+        # `scripts/wheel_import_walk.py` rather than a heredoc because
+        # `upstream-drift` needs exactly the same one against re-resolved
+        # dependencies, and two copies of it would drift apart.
         run: |
           uv venv --python 3.12 /tmp/wheelcheck
           uv pip install --python /tmp/wheelcheck/bin/python "$(echo dist/*.whl)[all]"
           cd /tmp
-          SOURCE_TREE="$GITHUB_WORKSPACE" /tmp/wheelcheck/bin/python - <<'PY'
-          import importlib
-          import os
-          import pkgutil
-          import sys
-          from pathlib import Path
-
-          import grapharc
-
-          assert "/tmp/wheelcheck/" in grapharc.__file__, grapharc.__file__
-          from grapharc import Budget, GraphARC, GraphARCState  # noqa: F401
-          from grapharc.gateway import get_model  # noqa: F401
-          from grapharc.harness import Harness  # noqa: F401
-
-          # Compared against the checkout rather than a magic number. A `walked
-          # > N` check cannot notice a whole subpackage going missing, and one
-          # did go missing in testing: hatchling treats `.gitignore` as a build
-          # exclusion unless `ignore-vcs` is set, and the build still succeeds.
-          source = Path(os.environ["SOURCE_TREE"]) / "grapharc"
-          expected = {
-              ".".join(("grapharc", *path.relative_to(source).parts))[: -len(".py")].removesuffix(
-                  ".__init__"
-              )
-              for path in source.rglob("*.py")
-              if "__pycache__" not in path.parts
-          }
-          installed = {m.name for m in pkgutil.walk_packages(grapharc.__path__, "grapharc.")}
-          installed.add("grapharc")
-
-          missing = sorted(expected - installed)
-          if missing:
-              sys.exit(f"in the source tree but not in the wheel: {missing}")
-
-          for name in sorted(installed):
-              importlib.import_module(name)
-          print(f"ok: {len(installed)} modules imported from wheel {grapharc.__version__}")
-          PY
+          /tmp/wheelcheck/bin/python "$GITHUB_WORKSPACE/scripts/wheel_import_walk.py" \
+            --source-tree "$GITHUB_WORKSPACE" --expect-prefix /tmp/wheelcheck/
           /tmp/wheelcheck/bin/grapharc --version
       - name: Sdist installs and imports in a clean environment
         run: |

scripts/wheel_import_walk.py

@@ -0,0 +1,95 @@
+"""Every module in the source tree is in the installed wheel, and imports.
+
+Run against a *clean* environment that has `grapharc` installed from a built
+wheel, from a working directory outside the checkout — otherwise `import
+grapharc` can fall back to the source tree and pass for the wrong reason. This
+file lives in `scripts/`, which contains no `grapharc` package, so running it by
+path does not put the checkout on `sys.path` either.
+
+Two jobs need exactly this check, which is why it is a file rather than a
+heredoc:
+
+- `build`, against the dependencies `uv.lock` pins — the shipped artifact is
+  importable;
+- `upstream-drift`, against dependencies re-resolved from `pyproject.toml` with
+  no ceiling — the shipped artifact is *still* importable once upstream moves.
+  That is the half issue #103 asked for: `uv.lock` hides a new major from every
+  other job, because keeping development reproducible is the lockfile's whole
+  job.
+
+The comparison is against the checkout rather than a magic number. A `walked >
+N` check cannot notice a whole subpackage going missing, and one did go missing
+in testing: hatchling treats `.gitignore` as a build exclusion unless
+`ignore-vcs` is set, and the build still succeeds.
+"""
+
+from __future__ import annotations
+
+import argparse
+import importlib
+import pkgutil
+import sys
+from pathlib import Path
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        "--source-tree",
+        required=True,
+        type=Path,
+        help="the checkout to compare against (the directory holding grapharc/)",
+    )
+    parser.add_argument(
+        "--expect-prefix",
+        required=True,
+        help="a path fragment the imported package must come from, e.g. /tmp/wheelcheck/",
+    )
+    args = parser.parse_args()
+
+    import grapharc
+
+    if args.expect_prefix not in grapharc.__file__:
+        return _fail(
+            f"imported grapharc from {grapharc.__file__}, which is not under "
+            f"{args.expect_prefix!r} — the installed wheel is not what was imported"
+        )
+
+    # The public entry points, named explicitly: these are what a reader of the
+    # README types first, so a wheel that walks cleanly and cannot do these is
+    # still broken.
+    from grapharc import Budget, GraphARC, GraphARCState  # noqa: F401
+    from grapharc.gateway import get_model  # noqa: F401
+    from grapharc.harness import Harness  # noqa: F401
+
+    source = args.source_tree / "grapharc"
+    if not source.is_dir():
+        return _fail(f"no grapharc package under {args.source_tree}")
+
+    expected = {
+        ".".join(("grapharc", *path.relative_to(source).parts))[: -len(".py")].removesuffix(
+            ".__init__"
+        )
+        for path in source.rglob("*.py")
+        if "__pycache__" not in path.parts
+    }
+    installed = {module.name for module in pkgutil.walk_packages(grapharc.__path__, "grapharc.")}
+    installed.add("grapharc")
+
+    missing = sorted(expected - installed)
+    if missing:
+        return _fail(f"in the source tree but not in the wheel: {missing}")
+
+    for name in sorted(installed):
+        importlib.import_module(name)
+    print(f"ok: {len(installed)} modules imported from wheel {grapharc.__version__}")
+    return 0
+
+
+def _fail(message: str) -> int:
+    print(f"error: {message}", file=sys.stderr)
+    return 1
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())