Allow prompt version selection without inputs

internal/adapter/http/handler_test.go

@@ -192,6 +192,124 @@ func TestHandlerPostRunsSuccessWithExplicitProfileID(t *testing.T) {
 	}
 }
 
+func TestHandlerAllowsOmittedInputsAndMapsPromptVersion(t *testing.T) {
+	r := &fakeRunner{result: &promptkit.RunResult{
+		Artifact:             promptkit.Artifact{Body: []byte("ok")},
+		Validation:           promptkit.ValidationResult{Status: promptkit.ValidationPassed, Mode: promptkit.ValidationNone, IsValid: true},
+		EffectiveModelParams: promptkit.ExecutionTarget{Endpoint: "http://llm/v1", Model: "m1"},
+	}}
+	h := NewHandler(r)
+
+	for _, body := range []string{
+		`{"prompt_id":"prompt-1","prompt_version":"2"}`,
+		`{"prompt_id":"prompt-1","prompt_version":"2","inputs":{}}`,
+	} {
+		req := httptest.NewRequest(http.MethodPost, "/v1/runs", bytes.NewBufferString(body))
+		w := httptest.NewRecorder()
+		h.ServeHTTP(w, req)
+
+		if w.Code != http.StatusOK {
+			t.Fatalf("expected 200, got %d body=%s", w.Code, w.Body.String())
+		}
+		if r.last.PromptVersion != "2" {
+			t.Fatalf("expected prompt version to be mapped, got %q", r.last.PromptVersion)
+		}
+		if r.last.Inputs != nil {
+			t.Fatalf("expected omitted or empty inputs to remain nil, got %#v", r.last.Inputs)
+		}
+	}
+}
+
+func TestHandlerDelegatesDefinitionInputRequirements(t *testing.T) {
+	tests := []struct {
+		name       string
+		definition string
+		wantStatus int
+		wantCode   string
+	}{
+		{
+			name: "no declared inputs",
+			definition: `id: p
+version: "1"
+default_profile: exec
+messages:
+  - role: user
+    content: "hello"
+output:
+  format: text
+  validation_mode: none
+`,
+			wantStatus: http.StatusOK,
+		},
+		{
+			name: "optional input omitted",
+			definition: `id: p
+version: "1"
+default_profile: exec
+inputs:
+  - name: note
+    required: false
+messages:
+  - role: user
+    content: "hello"
+output:
+  format: text
+  validation_mode: none
+`,
+			wantStatus: http.StatusOK,
+		},
+		{
+			name: "required input omitted",
+			definition: `id: p
+version: "1"
+default_profile: exec
+inputs:
+  - name: note
+    required: true
+messages:
+  - role: user
+    content: "hello"
+output:
+  format: text
+  validation_mode: none
+`,
+			wantStatus: http.StatusBadRequest,
+			wantCode:   "prompt_render_failed",
+		},
+		{
+			name: "template input omitted",
+			definition: `id: p
+version: "1"
+default_profile: exec
+messages:
+  - role: user
+    content: '{{input "note"}}'
+output:
+  format: text
+  validation_mode: none
+`,
+			wantStatus: http.StatusBadRequest,
+			wantCode:   "prompt_render_failed",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			h := newDefinitionHandler(t, tc.definition)
+			req := httptest.NewRequest(http.MethodPost, "/v1/runs", bytes.NewBufferString(`{"prompt_id":"p"}`))
+			w := httptest.NewRecorder()
+			h.ServeHTTP(w, req)
+
+			if w.Code != tc.wantStatus {
+				t.Fatalf("expected %d, got %d body=%s", tc.wantStatus, w.Code, w.Body.String())
+			}
+			if tc.wantCode != "" {
+				assertHTTPErrorCode(t, w, tc.wantStatus, tc.wantCode)
+			}
+		})
+	}
+}
+
 func TestHandlerInlineRefsWorkWithoutArtifactRoot(t *testing.T) {
 	h := newArtifactRootHandler(t, "")
 
@@ -931,6 +1049,31 @@ model: model
 	return engine
 }
 
+func newDefinitionHandler(t *testing.T, definition string) *Handler {
+	t.Helper()
+
+	promptDir := t.TempDir()
+	profileDir := t.TempDir()
+	if err := os.WriteFile(filepath.Join(promptDir, "prompt.yaml"), []byte(definition), 0o644); err != nil {
+		t.Fatalf("write prompt fixture: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(profileDir, "profile.yaml"), []byte(`id: exec
+endpoint: http://example.invalid/v1
+model: model
+`), 0o644); err != nil {
+		t.Fatalf("write profile fixture: %v", err)
+	}
+
+	engine, err := promptkit.NewEngine(promptkit.Config{
+		PromptDir:  promptDir,
+		ProfileDir: profileDir,
+	}, promptkit.WithLLMClient(handlerLLMClient{}))
+	if err != nil {
+		t.Fatalf("construct public engine: %v", err)
+	}
+	return NewHandler(engine)
+}
+
 func assertHTTPErrorCode(t *testing.T, w *httptest.ResponseRecorder, status int, code string) {
 	t.Helper()