additive candidate confidence scoring

tests/test_candidate_graph.py

@@ -54,6 +54,7 @@ def test_candidate_generator_builds_review_seed_from_observed_facts():
     assert ability.source_refs[0].path == "README.md"
     interface_capability = ability.capabilities[0]
     assert interface_capability.name == "Expose Repository Interface"
+    assert interface_capability.confidence == 0.75
     assert interface_capability.features[0].type == "API"
     assert interface_capability.features[0].location == "app.py"
     assert interface_capability.evidence[0].strength == "strong"
@@ -94,3 +95,48 @@ def test_candidate_generator_enriches_descriptions_from_content_chunks():
 
     assert "MailRouter. Routes incoming customer email" in graph[0].description
     assert '@app.post("/classify")' in graph[0].capabilities[0].description
+
+
+def test_candidate_confidence_scoring_stays_conservative_for_weak_facts():
+    repository = Repository(
+        id=1,
+        name="WeakDocs",
+        url="/tmp/weak-docs",
+        description=None,
+        branch="main",
+        status="analyzed",
+    )
+
+    graph = CandidateGraphGenerator().generate(
+        repository,
+        [fact(1, "documentation", "README", "README.md")],
+    )
+
+    assert graph[0].confidence == 0.45
+    assert graph[0].capabilities == []
+
+
+def test_candidate_confidence_scoring_increases_with_supporting_facts():
+    repository = Repository(
+        id=1,
+        name="Supported",
+        url="/tmp/supported",
+        description=None,
+        branch="main",
+        status="analyzed",
+    )
+    facts = [
+        fact(1, "documentation", "README", "README.md"),
+        fact(2, "interface", "python route decorator", "app.py", '@app.get("/health")'),
+        fact(3, "test", "test_app.py", "tests/test_app.py"),
+        fact(4, "example", "client.py", "examples/client.py"),
+        fact(5, "framework", "FastAPI", "requirements.txt"),
+        fact(6, "language", "Python"),
+        fact(7, "manifest", "requirements.txt", "requirements.txt"),
+    ]
+
+    graph = CandidateGraphGenerator().generate(repository, facts)
+
+    assert graph[0].confidence == 1.0
+    assert graph[0].capabilities[0].confidence == 0.85
+    assert graph[0].capabilities[1].confidence == 0.75