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: