diff --git a/docs/roadmap/remediation.md b/docs/roadmap/remediation.md
index e361c75..5c66ffa 100644
--- a/docs/roadmap/remediation.md
+++ b/docs/roadmap/remediation.md
@@ -87,7 +87,13 @@ directory resolves from the pipeline root. Preserve digest relocation invariance
 
 ## 3. Enforce unique base definitions even when a profile removes them
 
-Status: Open — P2
+Status: Resolved — P2
+
+Resolution: Named-profile loading now validates the independently resolved base
+through the same ConfigKit definition and public metadata history before accepting
+the selected result. Duplicate ordinary or family definitions therefore fail even
+when an overlay nulls their container or all of Scriptorium. A single base owner
+with a legitimate profile override remains supported.
 
 **Evidence:** `rejectDuplicateBaseDefinitions` at
 `internal/config/pipeline_configkit.go:354` enumerates only artifact/family keys
diff --git a/internal/config/pipeline_configkit.go b/internal/config/pipeline_configkit.go
index 505eba3..023e817 100644
--- a/internal/config/pipeline_configkit.go
+++ b/internal/config/pipeline_configkit.go
@@ -42,18 +42,20 @@ type pipelineFieldOwnership struct {
 
 func loadPipelineWithConfigKit(path string, opts PipelineLoadOptions) (*PipelineConfig, error) {
 	profile := selectedPipelineProfileName(opts)
-	result, err := configkit.Load(configkit.File(path), configkit.Options[PipelineConfig]{
-		Imports: true,
-		Profile: profile,
-		Definition: configkit.Definition[PipelineConfig]{
-			Defaults: pipelineConfigDefaults,
-			Resolve:  resolvePipelineConfig,
-			Validate: validatePipelineConfigKit,
-		},
-	})
+	result, err := loadPipelineConfigKitResult(path, profile)
 	if err != nil {
 		return nil, describePipelineLoadError(err)
 	}
+	if profile != "" {
+		base, err := loadPipelineConfigKitResult(path, "")
+		if err != nil {
+			return nil, describePipelineLoadError(err)
+		}
+		baseConfig := base.Config
+		if err := rejectDuplicateBaseDefinitions(&baseConfig, base.Metadata(), base.Sources()); err != nil {
+			return nil, fmt.Errorf("load pipeline config: %w", err)
+		}
+	}
 	cfg := result.Config
 	metadata, err := pipelineMetadataFromConfigKit(&cfg, result, opts)
 	if err != nil {
@@ -63,6 +65,18 @@ func loadPipelineWithConfigKit(path string, opts PipelineLoadOptions) (*Pipeline
 	return &cfg, nil
 }
 
+func loadPipelineConfigKitResult(path, profile string) (*configkit.Result[PipelineConfig], error) {
+	return configkit.Load(configkit.File(path), configkit.Options[PipelineConfig]{
+		Imports: true,
+		Profile: profile,
+		Definition: configkit.Definition[PipelineConfig]{
+			Defaults: pipelineConfigDefaults,
+			Resolve:  resolvePipelineConfig,
+			Validate: validatePipelineConfigKit,
+		},
+	})
+}
+
 func describePipelineLoadError(err error) error {
 	return describeConfigKitLoadError("pipeline", err)
 }
diff --git a/internal/config/pipeline_configkit_test.go b/internal/config/pipeline_configkit_test.go
index fb61169..3a6f7f2 100644
--- a/internal/config/pipeline_configkit_test.go
+++ b/internal/config/pipeline_configkit_test.go
@@ -52,10 +52,10 @@ whisperx:
 
 func TestPipelineConfigKitRejectsDuplicateBaseDeclarations(t *testing.T) {
 	for _, test := range []struct {
-		name, first, second string
+		name, first, second, clearedContainer string
 	}{
-		{name: "artifact", first: "scriptorium:\n  artifacts:\n    recap:\n      prompt_id: recap\n", second: "scriptorium:\n  artifacts:\n    recap:\n      output_path: artifacts/recap.md\n"},
-		{name: "artifact family", first: "scriptorium:\n  artifact_families:\n    recap:\n      for_each: party.characters\n", second: "scriptorium:\n  artifact_families:\n    recap:\n      output_path_pattern: artifacts/{character_id}.md\n"},
+		{name: "artifact", first: "scriptorium:\n  artifacts:\n    recap:\n      prompt_id: recap\n", second: "scriptorium:\n  artifacts:\n    recap:\n      output_path: artifacts/recap.md\n", clearedContainer: "scriptorium:\n  artifacts: null\n"},
+		{name: "artifact family", first: "scriptorium:\n  artifact_families:\n    recap:\n      for_each: party.characters\n", second: "scriptorium:\n  artifact_families:\n    recap:\n      output_path_pattern: artifacts/{character_id}.md\n", clearedContainer: "scriptorium:\n  artifact_families: null\n"},
 	} {
 		t.Run(test.name, func(t *testing.T) {
 			dir := t.TempDir()
@@ -68,16 +68,46 @@ whisperx:
 `)
 			writePipelineFixture(t, dir, "first.yml", test.first)
 			writePipelineFixture(t, dir, "second.yml", test.second)
+			writePipelineFixture(t, dir, "profiles/clear-container.yml", test.clearedContainer)
+			writePipelineFixture(t, dir, "profiles/clear-scriptorium.yml", "scriptorium: null\n")
 
-			_, err := LoadPipeline(filepath.Join(dir, "pipeline.yml"))
-			if err == nil || !strings.Contains(err.Error(), "declared by multiple base files") ||
-				!strings.Contains(err.Error(), "first.yml") || !strings.Contains(err.Error(), "second.yml") {
-				t.Fatalf("duplicate declaration error = %v", err)
+			for _, profile := range []string{"", "clear-container", "clear-scriptorium"} {
+				t.Run(profile, func(t *testing.T) {
+					options := PipelineLoadOptions{}
+					if profile != "" {
+						options.Profile = &profile
+					}
+					_, err := LoadPipelineWithOptions(filepath.Join(dir, "pipeline.yml"), options)
+					if err == nil || !strings.Contains(err.Error(), "declared by multiple base files") ||
+						!strings.Contains(err.Error(), "first.yml") || !strings.Contains(err.Error(), "second.yml") {
+						t.Fatalf("duplicate declaration error = %v", err)
+					}
+				})
 			}
 		})
 	}
 }
 
+func TestPipelineConfigKitAllowsOneBaseDeclarationWithProfileOverride(t *testing.T) {
+	dir := t.TempDir()
+	writePipelineFixture(t, dir, "pipeline.yml", `configkit:
+  imports:
+    - path: artifact.yml
+whisperx:
+  transcribe_url: https://transcription.example.test/transcribe
+`)
+	writePipelineFixture(t, dir, "artifact.yml", "scriptorium:\n  artifacts:\n    recap:\n      prompt_id: base\n      output_path: artifacts/recap.md\n")
+	writePipelineFixture(t, dir, "profiles/testing.yml", "scriptorium:\n  artifacts:\n    recap:\n      prompt_id: testing\n")
+	profile := "testing"
+	cfg, err := LoadPipelineWithOptions(filepath.Join(dir, "pipeline.yml"), PipelineLoadOptions{Profile: &profile})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := cfg.Scriptorium.Artifacts["recap"].PromptID; got != "testing" {
+		t.Fatalf("profile prompt = %q, want testing", got)
+	}
+}
+
 func TestPipelineConfigKitRejectsUnknownDirectiveAlias(t *testing.T) {
 	dir := t.TempDir()
 	path := writePipelineFixture(t, dir, "pipeline.yml", "composition:\n  imports: []\n")