deterministic input/output hints for interface capabilities

src/repo_registry/candidate_graph/generator.py

@@ -138,8 +138,8 @@ class CandidateGraphGenerator:
         return CandidateCapabilityDraft(
             name="Expose Repository Interface",
             description=self._interface_description(chunks),
-            inputs=[],
-            outputs=["callable interface"],
+            inputs=self._interface_inputs(interfaces),
+            outputs=self._interface_outputs(interfaces),
             confidence=self._interface_confidence(
                 interfaces=interfaces,
                 tests=tests,
@@ -195,6 +195,28 @@ class CandidateGraphGenerator:
             return "API"
         return "interface"
 
+    def _interface_inputs(self, interfaces: list[ObservedFact]) -> list[str]:
+        feature_types = {self._feature_type(fact) for fact in interfaces}
+        inputs: list[str] = []
+        if "API" in feature_types:
+            inputs.append("HTTP request")
+        if "CLI" in feature_types:
+            inputs.append("CLI arguments")
+        if not inputs:
+            inputs.append("caller input")
+        return inputs
+
+    def _interface_outputs(self, interfaces: list[ObservedFact]) -> list[str]:
+        feature_types = {self._feature_type(fact) for fact in interfaces}
+        outputs: list[str] = []
+        if "API" in feature_types:
+            outputs.append("HTTP response")
+        if "CLI" in feature_types:
+            outputs.append("command output")
+        if not outputs:
+            outputs.append("callable interface result")
+        return outputs
+
     def _feature_name(self, fact: ObservedFact, chunks: list[ContentChunk]) -> str:
         route_name = self._route_feature_name(fact.value)
         if route_name:

tests/test_candidate_graph.py

@@ -55,6 +55,8 @@ def test_candidate_generator_builds_review_seed_from_observed_facts():
     interface_capability = ability.capabilities[0]
     assert interface_capability.name == "Expose Repository Interface"
     assert interface_capability.confidence == 0.75
+    assert interface_capability.inputs == ["HTTP request"]
+    assert interface_capability.outputs == ["HTTP response"]
     assert interface_capability.features[0].type == "API"
     assert interface_capability.features[0].name == "POST /classify"
     assert interface_capability.features[0].location == "app.py"
@@ -180,5 +182,29 @@ def test_candidate_generator_names_cli_features_from_nearby_function():
     graph = CandidateGraphGenerator().generate(repository, facts, chunks)
 
     feature = graph[0].capabilities[0].features[0]
+    capability = graph[0].capabilities[0]
     assert feature.type == "CLI"
     assert feature.name == "CLI command import_repositories"
+    assert capability.inputs == ["CLI arguments"]
+    assert capability.outputs == ["command output"]
+
+
+def test_candidate_generator_uses_generic_io_for_unknown_interfaces():
+    repository = Repository(
+        id=1,
+        name="UnknownInterface",
+        url="/tmp/unknown-interface",
+        description=None,
+        branch="main",
+        status="analyzed",
+    )
+    facts = [
+        fact(1, "documentation", "README", "README.md"),
+        fact(2, "interface", "possible surface", "src/plugin.py"),
+    ]
+
+    graph = CandidateGraphGenerator().generate(repository, facts)
+
+    capability = graph[0].capabilities[0]
+    assert capability.inputs == ["caller input"]
+    assert capability.outputs == ["callable interface result"]