Correct engine construction edge cases

engine_test.go

@@ -2374,6 +2374,116 @@ func TestRunStructuredOutputWorksWithSchemaFile(t *testing.T) {
 	}
 }
 
+func TestSingleFileOptionsPreserveWhitespaceInPaths(t *testing.T) {
+	profile := promptkit.Profile{
+		ID:       "exact-path-profile",
+		Endpoint: "http://example.test/v1",
+		Model:    "exact-path-model",
+	}
+	promptDocument := []byte(`
+id: exact-path-prompt
+version: "1.0.0"
+default_profile: exact-path-profile
+messages:
+  - role: user
+    content: exact path
+output:
+  format: text
+  validation_mode: none
+`)
+	profileDocument := []byte(`
+id: exact-path-profile
+endpoint: http://example.test/v1
+model: exact-path-model
+`)
+
+	tests := []struct {
+		name     string
+		baseName string
+		content  []byte
+		engine   func(string) (*promptkit.Engine, error)
+	}{
+		{
+			name:     "prompt",
+			baseName: "prompt.yaml",
+			content:  promptDocument,
+			engine: func(path string) (*promptkit.Engine, error) {
+				return promptkit.NewEngine(promptkit.Config{},
+					promptkit.WithPromptFile(path),
+					promptkit.WithProfiles(profile),
+				)
+			},
+		},
+		{
+			name:     "profile",
+			baseName: "profile.yaml",
+			content:  profileDocument,
+			engine: func(path string) (*promptkit.Engine, error) {
+				return promptkit.NewEngine(promptkit.Config{},
+					promptkit.WithPromptFS(contractPromptFS("exact-path-prompt", "exact-path-profile", "exact path"), "."),
+					promptkit.WithProfileFile(path),
+				)
+			},
+		},
+		{
+			name:     "schema",
+			baseName: "schema.json",
+			content:  []byte(publicSchemaJSON()),
+			engine: func(path string) (*promptkit.Engine, error) {
+				promptSource := fstest.MapFS{
+					"prompt.yaml": &fstest.MapFile{Data: []byte(fmt.Sprintf(`
+id: exact-path-prompt
+version: "1.0.0"
+default_profile: exact-path-profile
+messages:
+  - role: user
+    content: exact path
+output:
+  format: json
+  validation_mode: json_schema
+  schema_path: %q
+`, filepath.Base(path)))},
+				}
+				return promptkit.NewEngine(promptkit.Config{},
+					promptkit.WithPromptFS(promptSource, "."),
+					promptkit.WithProfiles(profile),
+					promptkit.WithSchemaFile(path),
+				)
+			},
+		},
+	}
+	positions := []struct {
+		name   string
+		prefix string
+		suffix string
+	}{
+		{name: "leading whitespace", prefix: " "},
+		{name: "trailing whitespace", suffix: " "},
+	}
+
+	for _, tc := range tests {
+		for _, position := range positions {
+			t.Run(tc.name+"/"+position.name, func(t *testing.T) {
+				path := filepath.Join(t.TempDir(), position.prefix+tc.baseName+position.suffix)
+				if err := os.WriteFile(path, tc.content, 0o644); err != nil {
+					t.Fatalf("write source file: %v", err)
+				}
+				engine, err := tc.engine(path)
+				if err != nil {
+					t.Fatalf("construct engine from exact path %q: %v", path, err)
+				}
+				prepared, err := engine.Prepare(context.Background(), promptkit.RunRequest{PromptID: "exact-path-prompt"})
+				if err != nil {
+					t.Fatalf("prepare from exact path %q: %v", path, err)
+				}
+				if prepared.EffectiveModelParams.Model != "exact-path-model" {
+					t.Fatalf("prepared model = %q, want exact-path-model", prepared.EffectiveModelParams.Model)
+				}
+			})
+		}
+	}
+}
+
 func TestSourceOptionsRejectInvalidInputs(t *testing.T) {
 	missingFile := filepath.Join(t.TempDir(), "missing.yaml")
 	directoryPath := t.TempDir()
@@ -2405,6 +2515,16 @@ func TestSourceOptionsRejectInvalidInputs(t *testing.T) {
 			}
 		})
 	}
+
+	t.Run("later valid replacement does not hide invalid option", func(t *testing.T) {
+		_, err := promptkit.NewEngine(promptkit.Config{PromptDir: frameworkPromptDir},
+			promptkit.WithProfileFS(nil, "profiles"),
+			promptkit.WithProfileFS(contractProfileFS("profile", "model"), "."),
+		)
+		if !errors.Is(err, promptkit.ErrInvalidConfig) {
+			t.Fatalf("expected ErrInvalidConfig, got %v", err)
+		}
+	})
 }
 
 func TestPackageOptionsComposeFromSlice(t *testing.T) {