From 9fe553461edfe508c94d042e1aeac42fbfeeefcc Mon Sep 17 00:00:00 2001
From: Alexandre Dulaunoy <a@foo.be>
Date: Tue, 1 Sep 2026 10:34:18 +0200
Subject: [PATCH] chore: isolate Rust implementation directory

---
 .gitignore                      |  1 +
 CONTRIBUTING.md                 |  5 +++++
 rust/README.md                  |  8 ++++++++
 tests/test_repository_layout.py | 21 +++++++++++++++++++++
 4 files changed, 35 insertions(+)
 create mode 100644 rust/README.md
 create mode 100644 tests/test_repository_layout.py

diff --git a/.gitignore b/.gitignore
index 17b6b7d..1f30d2f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,7 @@ __pycache__/
 *.egg-info/
 build/
 dist/
+target/
 .pytest_cache/
 .ruff_cache/
 rulezet-validation.toml
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index dfae841..bfed57f 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -30,8 +30,13 @@ src/rulezet_validation/
   sync.py       orchestration
   cli.py        argparse wiring only, no logic
   baseline/     manifest + the bundled probes
+rust/            all Rust crates and Rust implementation
 ```
 
+Rust source and Cargo manifests belong under the top-level `rust/` directory.
+The repository layout test enforces this boundary so Rust tooling does not become
+interspersed with the Python package.
+
 ## Things that will get a patch rejected
 
 **Anything other than a baseline hit moving a rule into quarantine.** The
diff --git a/rust/README.md b/rust/README.md
new file mode 100644
index 0000000..73d73ec
--- /dev/null
+++ b/rust/README.md
@@ -0,0 +1,8 @@
+# Rust implementation
+
+All Rust crates, Cargo manifests, and Rust source code for this project live in
+this directory. Keeping the Rust implementation here gives Cargo an isolated
+workspace while leaving the Python package under `src/rulezet_validation/`.
+
+New Rust crates should be created as children of this directory. Do not place
+`Cargo.toml`, `Cargo.lock`, or `*.rs` files elsewhere in the repository.
diff --git a/tests/test_repository_layout.py b/tests/test_repository_layout.py
new file mode 100644
index 0000000..1175807
--- /dev/null
+++ b/tests/test_repository_layout.py
@@ -0,0 +1,21 @@
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+RUST_ROOT = ROOT / "rust"
+RUST_FILES = {"Cargo.toml", "Cargo.lock"}
+
+
+def test_rust_implementation_is_contained_in_rust_directory():
+    misplaced = []
+
+    for path in ROOT.rglob("*"):
+        if any(part in {".git", ".venv", "target"} for part in path.parts):
+            continue
+        if path.is_file() and (path.suffix == ".rs" or path.name in RUST_FILES):
+            if not path.is_relative_to(RUST_ROOT):
+                misplaced.append(path.relative_to(ROOT).as_posix())
+
+    assert misplaced == [], (
+        "Rust source and Cargo files must live under rust/: "
+        + ", ".join(misplaced)
+    )