Show contribution tracks at the top of CONTRIBUTING.md

CONTRIBUTING.md

@@ -3,6 +3,20 @@
 We welcome contributions! We all benefit when new ideas, skills, and reviewer
 perspectives are shared across the open-source community.
 
+## Which track is my change?
+
+Pick a track before you open an issue or PR. The full rules for each track are
+in [Contribution Tracks & Workflow](#contribution-tracks--workflow); this
+section points to them.
+
+*   **Small fix within the Track 1 limits:** open a PR with the
+    [PR template](.github/PULL_REQUEST_TEMPLATE.md).
+*   **New feature, architectural change, or anything over the Track 1
+    limits:** open a
+    [feature proposal issue](https://github.com/google/elephant-goldfish-model/issues/new?template=feature_proposal.md)
+    and follow the Track 2 steps. Existing design docs are listed in
+    [docs/designs/README.md](docs/designs/README.md).
+
 ## Design Principles
 
 These general principles guide development of the EGM framework:

tests/unit/test_link_integrity.py

@@ -39,13 +39,21 @@ def extract_headers(content: str) -> Set[str]:
   slugs = set()
   for match in HEADER_PATTERN.finditer(content):
     title = match.group(2).strip().lower()
-    # Normalize slug: remove punctuation, replace spaces with hyphens
-    slug = re.sub(r"[^a-z0-9\s-]", "", title)
-    slug = re.sub(r"\s+", "-", slug)
+    # Turn each space into its own hyphen, as GitHub does, so removed
+    # punctuation leaves "--": "Tracks & Workflow" -> "tracks--workflow".
+    slug = re.sub(r"[^a-z0-9 -]", "", title)
+    slug = slug.replace(" ", "-")
     slugs.add(slug)
   return slugs
 
 
+def test_heading_slug_keeps_one_hyphen_per_space() -> None:
+  """Verifies removed punctuation leaves a double hyphen, as on GitHub."""
+  assert extract_headers("## Contribution Tracks & Workflow\n") == {
+      "contribution-tracks--workflow"
+  }
+
+
 def test_relative_markdown_links_resolve_on_disk(
     repo_root: pathlib.Path,
 ) -> None: