Milestone 3: candidate graph generation

tests/test_candidate_graph.py

@@ -0,0 +1,45 @@
+from repo_registry.candidate_graph.generator import CandidateGraphGenerator
+from repo_registry.core.models import ObservedFact, Repository
+
+
+def fact(id, kind, name, path="", value=""):
+    return ObservedFact(
+        id=id,
+        repository_id=1,
+        analysis_run_id=1,
+        snapshot_id=1,
+        kind=kind,
+        path=path,
+        name=name,
+        value=value,
+        metadata={},
+    )
+
+
+def test_candidate_generator_builds_review_seed_from_observed_facts():
+    repository = Repository(
+        id=1,
+        name="MailRouter",
+        url="/tmp/mail-router",
+        description=None,
+        branch="main",
+        status="analyzed",
+    )
+    facts = [
+        fact(1, "documentation", "README", "README.md"),
+        fact(2, "interface", "python route decorator", "app.py", '@app.post("/classify")'),
+        fact(3, "test", "test_app.py", "tests/test_app.py"),
+        fact(4, "framework", "FastAPI", "requirements.txt"),
+    ]
+
+    graph = CandidateGraphGenerator().generate(repository, facts)
+
+    assert len(graph) == 1
+    ability = graph[0]
+    assert ability.name == "Review MailRouter Repository Usefulness"
+    assert ability.source_refs[0].path == "README.md"
+    interface_capability = ability.capabilities[0]
+    assert interface_capability.name == "Expose Repository Interface"
+    assert interface_capability.features[0].type == "API"
+    assert interface_capability.features[0].location == "app.py"
+    assert interface_capability.evidence[0].strength == "strong"