Hosted Hatch scan exits 0 "redirected" when [tool.uv.sources] pins the patched package, but Hatch's uv installer obeys the source: url/path sources install the unpatched wheel and git sources break every install #673

[agent] Found by the scheduled Hatch bug-hunt routine (ledger #314).

Summary

In a Hatch project whose environment uses installer = "uv", a [tool.uv.sources] entry for the patched package (for example a url, path or git source) takes precedence over the PEP 508 direct reference that hosted mode writes into [project].dependencies. Hatch installs the project with uv pip install -e ., and uv applies the project's tool.uv.sources. Hosted scan never looks at [tool.uv.sources]. It rewrites six==1.16.0 to six @ <patch url>#sha256=… and reports success, redirected: 1, exit 0. Then:

• with a url or path source, every fresh Hatch env silently installs the unpatched upstream wheel;
• with a git source, every Hatch env creation fails with Conflicting URLs for package six.

The docs say a source table is refused before anything is written, so the scan should have failed closed.

Impact

CI gets a green scan and a pyproject that looks patched, but the vulnerable code still ships. For git sources the project stops installing at all. vex does correctly omit six (not_applied) when it inspects the env, so the silent part is the scan result. Vendored mode on the same project refuses (with pypi_uv_no_lockfile), so it fails closed.

Repro (Hatch 1.18.1, uv 0.12, Linux; local mock patch API serving a patched six 1.16.0 wheel)

mkdir app && cd app && mkdir -p src/app && touch src/app/__init__.py
cat > pyproject.toml <<'EOF'
[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"

[project]
name = "app"
version = "0.1.0"
dependencies = ["six==1.16.0"]

[tool.hatch.envs.default]
installer = "uv"

[tool.uv.sources]
six = { url = "https://files.pythonhosted.org/packages/d9/5a/e7c31adbe875f2abbb91bd84cf2dc52d792b5a01506781dbcf25c91daf11/six-1.16.0-py2.py3-none-any.whl" }
EOF
socket-patch scan --mode hosted --yes --json --ecosystems pypi …   # exit 0, status success, redirect.redirected = 1, no warnings
grep dependencies pyproject.toml   # six @ http://…/patch/pypi/six/1.16.0/…/six-1.16.0-py2.py3-none-any.whl#sha256=…
hatch run python -c 'import six; print(getattr(six, "SOCKET_PATCHED", "UNPATCHED"))'   # fresh env -> UNPATCHED

Swap the source for { path = "/abs/six-1.16.0-py2.py3-none-any.whl" } to get the same result. With { git = "https://github.com/benjaminp/six", tag = "1.16.0" }, hatch run fails with:

error: Requirements contain conflicting URLs for package `six`:
- git+https://github.com/benjaminp/[email protected]
- http://127.0.0.1:18080/patch/pypi/six/1.16.0/…/six-1.16.0-py2.py3-none-any.whl

Expected vs actual

• Expected: docs/testing/hatch.md: "A range, transitive-only declaration, dynamic dependency metadata, custom environment plugin, source table or conditional override is refused before writing. Use agent mode…". A uv source for a package Hatch installs through uv should be refused (or at least warned about) the same way Hatch sources are, with nothing written and a non-zero or warning result.
• Actual: exit 0 success, redirected: 1, no warning. The rewrite is either ignored (url/path) or breaks installs (git).

Matrix (Linux, each cell run twice)

macOS / Windows: not probed (probe branches can't be deleted from this sandbox right now). The rewrite is OS-independent.

Suspect code

crates/socket-patch-core/src/utils/hatch.rs:247 refuses only Hatch's own tool.hatch.sources / env. plan() (utils/hatch.rs:344) reads installer == "uv" for the env but never consults tool.uv.sources, so rewrite_project (utils/hatch.rs:187) rewrites a dependency that uv then resolves from the source. A fix could refuse (or warn and skip) any patched name that appears in [tool.uv.sources] when an env that installs the project uses the uv installer.

Related but different: #564 (uv lane, no-sources = true).

Backlog review — 2026-10-08

Priority: P1 → P2. Hatch/uv URL or path overrides can keep installing upstream bytes despite the hosted scan; git overrides cause an install failure. VEX rejects the mismatched environment. Retain this real source-selection defect at P2.