diff --git a/README.md b/README.md
index 946c39a..cf8d54a 100644
--- a/README.md
+++ b/README.md
@@ -105,6 +105,8 @@ Trim outputs and diagnostics:
   - `logs/scriptorium.bounds.render.stderr.log`
   - `config/scriptorium.bounds.render.generated.yml`
 
+Render-debug files are diagnostics and are not treated as canonical stage output artifact refs.
+
 ## Scriptorium Configuration
 
 `pipeline.scriptorium` is optional. When present, Narratio validates and uses it for analyze-stage artifact generation.
diff --git a/architecture.md b/architecture.md
index 9c45683..0495cbb 100644
--- a/architecture.md
+++ b/architecture.md
@@ -196,6 +196,8 @@ Expected trim outputs and diagnostics:
   - `logs/scriptorium.bounds.render.stderr.log`
   - `config/scriptorium.bounds.render.generated.yml`
 
+Render-debug files are diagnostics. They are recorded in stage metadata/log/config refs and are not treated as canonical stage output artifact refs.
+
 ## 8. Analyze Stage (Current Implementation)
 
 The current real analyze implementation supports only `scriptorium.artifacts.session_recap`.
diff --git a/internal/adapters/seriatim/runner.go b/internal/adapters/seriatim/runner.go
index 17bd295..313ba3d 100644
--- a/internal/adapters/seriatim/runner.go
+++ b/internal/adapters/seriatim/runner.go
@@ -6,8 +6,6 @@ import (
 	"time"
 )
 
-// TODO: implement a real Seriatim subprocess adapter.
-
 // Runner is the adapter boundary for seriatim merge/trim invocations.
 type Runner interface {
 	Run(ctx context.Context, req MergeRequest) (MergeResult, error)
diff --git a/internal/config/config.go b/internal/config/config.go
index e65382d..66db116 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -84,7 +84,7 @@ type AuditaConfig struct {
 	Report                   *bool    `yaml:"report"`
 }
 
-// TrimConfig configures the future trim stage boundary.
+// TrimConfig configures trim-stage transcript boundary behavior.
 type TrimConfig struct {
 	Enabled    bool               `yaml:"enabled"`
 	OutputPath string             `yaml:"output_path"`
diff --git a/internal/stage/trim.go b/internal/stage/trim.go
index c02d096..517eaf0 100644
--- a/internal/stage/trim.go
+++ b/internal/stage/trim.go
@@ -329,14 +329,6 @@ func (trimStage) Run(ctx context.Context, env *Env, m *manifest.Manifest) (*Stag
 			AbsolutePath: finalBoundsOutputPath,
 		},
 	}
-	if renderOutputPath != "" {
-		outputs = append(outputs, artifacts.Ref{
-			Kind:         "session_bounds_render",
-			Category:     "artifacts",
-			SessionID:    sessionID,
-			AbsolutePath: renderOutputPath,
-		})
-	}
 
 	return &StageResult{
 		Outputs:          outputs,
diff --git a/internal/stage/trim_test.go b/internal/stage/trim_test.go
index 76a025e..dd1e220 100644
--- a/internal/stage/trim_test.go
+++ b/internal/stage/trim_test.go
@@ -112,6 +112,33 @@ func TestTrimStageRecordsLogAndGeneratedConfigRefs(t *testing.T) {
 	}
 }
 
+func TestTrimStageRenderDebugDiagnosticsAreNotStageOutputs(t *testing.T) {
+	env, m, scr, _ := setupTrimEnv(t)
+	paths := env.ArtifactStore.SessionPaths(m.SessionID)
+	writeFile(t, filepath.Join(paths.TranscriptsDir, "processed.json"), `{"segments":[{"id":1},{"id":2}]}`)
+	scr.BoundsBody = `{"trim_action":"trim","start_segment_id":1,"end_segment_id":2}`
+
+	cfg := *env.Config.Pipeline.Trim
+	cfg.Bounds.RenderDebug = true
+	env.Config.Pipeline.Trim = &cfg
+
+	result, err := (trimStage{}).Run(context.Background(), env, m)
+	if err != nil {
+		t.Fatalf("trim.Run() error = %v", err)
+	}
+	if len(scr.RenderRequests) != 1 {
+		t.Fatalf("scriptorium render requests = %d, want 1", len(scr.RenderRequests))
+	}
+	for _, out := range result.Outputs {
+		if out.Kind == "session_bounds_render" {
+			t.Fatalf("render diagnostics should not be stage outputs: %#v", result.Outputs)
+		}
+	}
+	if result.Metadata["bounds_render_output_path"] == nil {
+		t.Fatalf("bounds_render_output_path metadata missing: %#v", result.Metadata)
+	}
+}
+
 func TestTrimStageFailsWhenProcessedTranscriptMissing(t *testing.T) {
 	env, m, _, _ := setupTrimEnv(t)
 	_, err := (trimStage{}).Run(context.Background(), env, m)