Fix config validation edge cases

internal/core/config/file_config_test.go

@@ -234,6 +234,89 @@ llm_profiles:
 	}
 }
 
+func TestApplyFileConfigRejectsDuplicateTrimmedLLMProfileIDs(t *testing.T) {
+	fileCfg, err := ParseFileConfigYAML([]byte(`
+version: 1
+llm_profiles:
+  default:
+    model: first
+  " default ":
+    model: second
+`))
+	if err != nil {
+		t.Fatalf("ParseFileConfigYAML: %v", err)
+	}
+
+	cfg := Default()
+	err = cfg.applyFileConfigWithLookup(fileCfg, emptyLookup)
+	if err == nil || !strings.Contains(err.Error(), "llm profile id") || !strings.Contains(err.Error(), "duplicated") {
+		t.Fatalf("expected duplicate LLM profile ID error, got %v", err)
+	}
+}
+
+func TestApplyFileConfigRejectsDuplicateTrimmedPipelineIDs(t *testing.T) {
+	fileCfg, err := ParseFileConfigYAML([]byte(`
+version: 1
+pipelines:
+  example:
+    input: fake/input
+  " example ":
+    input: fake/other-input
+`))
+	if err != nil {
+		t.Fatalf("ParseFileConfigYAML: %v", err)
+	}
+
+	cfg := Default()
+	err = cfg.applyFileConfigWithLookup(fileCfg, emptyLookup)
+	if err == nil || !strings.Contains(err.Error(), "pipeline id") || !strings.Contains(err.Error(), "duplicated") {
+		t.Fatalf("expected duplicate pipeline ID error, got %v", err)
+	}
+}
+
+func TestApplyFileConfigRejectsDuplicateTrimmedArtifactLaneIDs(t *testing.T) {
+	fileCfg, err := ParseFileConfigYAML([]byte(`
+version: 1
+pipelines:
+  example:
+    input: fake/input
+    artifacts:
+      events:
+        extract: fake/extract
+      " events ":
+        extract: fake/other-extract
+`))
+	if err != nil {
+		t.Fatalf("ParseFileConfigYAML: %v", err)
+	}
+
+	cfg := Default()
+	err = cfg.applyFileConfigWithLookup(fileCfg, emptyLookup)
+	if err == nil || !strings.Contains(err.Error(), `pipeline "example" artifact lane id`) || !strings.Contains(err.Error(), "duplicated") {
+		t.Fatalf("expected duplicate artifact lane ID error, got %v", err)
+	}
+}
+
+func TestApplyFileConfigAllowsRetryOnlyLLMProfile(t *testing.T) {
+	cfg := parseAndApplyConfig(t, `
+version: 1
+llm_profiles:
+  retry-only:
+    max_retries: 3
+`)
+
+	profile := cfg.LLMProfiles["retry-only"]
+	if profile.MaxRetries != 3 {
+		t.Fatalf("unexpected max retries: %d", profile.MaxRetries)
+	}
+	if profile.TimeoutSeconds != 0 {
+		t.Fatalf("expected unset timeout, got %d", profile.TimeoutSeconds)
+	}
+	if profile.MaxConcurrency != 0 {
+		t.Fatalf("expected unset max concurrency, got %d", profile.MaxConcurrency)
+	}
+}
+
 func TestApplyFileConfigRejectsInvalidAPIKeyEnv(t *testing.T) {
 	tests := []struct {
 		name string