diff --git a/docs/config.md b/docs/config.md
index 64e4480..797150b 100644
--- a/docs/config.md
+++ b/docs/config.md
@@ -198,7 +198,7 @@ Rules:
 | `pipeline.render.format` | string | No | `markdown` (only supported value) |
 | `pipeline.render.title` | string | No | empty (falls back to `session.title` when set) |
 | `pipeline.render.include_timestamps` | bool | No | `true` |
-| `pipeline.render.include_segment_ids` | bool | No | `false` |
+| `pipeline.render.include_segment_ids` | bool | No | `true` |
 | `pipeline.render.include_metadata` | bool | No | `false` |
 | `pipeline.scriptorium.binary` | string | No | `scriptorium` |
 | `pipeline.scriptorium.config_path` | string | No | empty |
diff --git a/internal/adapters/seriatim/subprocess.go b/internal/adapters/seriatim/subprocess.go
index 835e3a7..124db7e 100644
--- a/internal/adapters/seriatim/subprocess.go
+++ b/internal/adapters/seriatim/subprocess.go
@@ -577,9 +577,9 @@ func buildRenderArgs(req RenderRequest, format string) []string {
 		"--input-file", req.InputTranscriptPath,
 		"--output-file", req.OutputRenderedPath,
 		"--format", format,
-		"--include-timestamps", strconv.FormatBool(req.IncludeTimestamps),
-		"--include-segment-ids", strconv.FormatBool(req.IncludeSegmentIDs),
-		"--include-metadata", strconv.FormatBool(req.IncludeMetadata),
+		"--include-timestamps=" + strconv.FormatBool(req.IncludeTimestamps),
+		"--include-segment-ids=" + strconv.FormatBool(req.IncludeSegmentIDs),
+		"--include-metadata=" + strconv.FormatBool(req.IncludeMetadata),
 	}
 	if strings.TrimSpace(req.Title) != "" {
 		args = append(args, "--title", req.Title)
diff --git a/internal/adapters/seriatim/subprocess_test.go b/internal/adapters/seriatim/subprocess_test.go
index d684db7..42e7af8 100644
--- a/internal/adapters/seriatim/subprocess_test.go
+++ b/internal/adapters/seriatim/subprocess_test.go
@@ -628,9 +628,9 @@ func TestSubprocessRunnerRenderSuccessInvocationAndProvenance(t *testing.T) {
 		"--input-file", req.InputTranscriptPath,
 		"--output-file", req.OutputRenderedPath,
 		"--format", req.Format,
-		"--include-timestamps", "true",
-		"--include-segment-ids", "false",
-		"--include-metadata", "true",
+		"--include-timestamps=true",
+		"--include-segment-ids=true",
+		"--include-metadata=false",
 		"--title", req.Title,
 	}
 	if strings.Join(rec.Args, "\n") != strings.Join(wantArgs, "\n") {
@@ -946,8 +946,8 @@ func renderReqForTest(t *testing.T) RenderRequest {
 		Format:              "markdown",
 		Title:               "Session 42",
 		IncludeTimestamps:   true,
-		IncludeSegmentIDs:   false,
-		IncludeMetadata:     true,
+		IncludeSegmentIDs:   true,
+		IncludeMetadata:     false,
 		GeneratedConfigPath: filepath.Join(dir, "seriatim.render.generated.yml"),
 		StdoutLogPath:       filepath.Join(dir, "seriatim.render.stdout.log"),
 		StderrLogPath:       filepath.Join(dir, "seriatim.render.stderr.log"),
diff --git a/internal/config/config.go b/internal/config/config.go
index 991bddc..38bcbb1 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -216,7 +216,7 @@ type RenderConfig struct {
 	Format            string `yaml:"format"`
 	Title             string `yaml:"title"`
 	IncludeTimestamps *bool  `yaml:"include_timestamps"`
-	IncludeSegmentIDs bool   `yaml:"include_segment_ids"`
+	IncludeSegmentIDs *bool  `yaml:"include_segment_ids"`
 	IncludeMetadata   bool   `yaml:"include_metadata"`
 }
 
diff --git a/internal/config/defaults.go b/internal/config/defaults.go
index 0898fda..2b6892a 100644
--- a/internal/config/defaults.go
+++ b/internal/config/defaults.go
@@ -44,7 +44,7 @@ const (
 	DefaultRenderFormat       = "markdown"
 	DefaultRenderTitle        = ""
 	DefaultRenderTimestamps   = true
-	DefaultRenderSegmentIDs   = false
+	DefaultRenderSegmentIDs   = true
 	DefaultRenderMetadata     = false
 
 	DefaultNormalizeOutputPath   = artifactmodel.TranscriptPathFinal
diff --git a/internal/config/load.go b/internal/config/load.go
index 6c17ef4..23c6944 100644
--- a/internal/config/load.go
+++ b/internal/config/load.go
@@ -527,6 +527,9 @@ func applyRenderDefaults(cfg **RenderConfig) {
 	if (*cfg).IncludeTimestamps == nil {
 		(*cfg).IncludeTimestamps = boolPtr(DefaultRenderTimestamps)
 	}
+	if (*cfg).IncludeSegmentIDs == nil {
+		(*cfg).IncludeSegmentIDs = boolPtr(DefaultRenderSegmentIDs)
+	}
 }
 
 func applyNormalizeDefaults(cfg *NormalizeConfig) {
diff --git a/internal/config/render_test.go b/internal/config/render_test.go
index 3deca70..5215bda 100644
--- a/internal/config/render_test.go
+++ b/internal/config/render_test.go
@@ -30,8 +30,8 @@ func TestRenderLoadAndValidate(t *testing.T) {
 				if cfg.Pipeline.Render.IncludeTimestamps == nil || !*cfg.Pipeline.Render.IncludeTimestamps {
 					t.Fatalf("render.include_timestamps = %#v, want true", cfg.Pipeline.Render.IncludeTimestamps)
 				}
-				if cfg.Pipeline.Render.IncludeSegmentIDs {
-					t.Fatalf("render.include_segment_ids = true, want false")
+				if cfg.Pipeline.Render.IncludeSegmentIDs == nil || !*cfg.Pipeline.Render.IncludeSegmentIDs {
+					t.Fatalf("render.include_segment_ids = %#v, want true", cfg.Pipeline.Render.IncludeSegmentIDs)
 				}
 				if cfg.Pipeline.Render.IncludeMetadata {
 					t.Fatalf("render.include_metadata = true, want false")
@@ -59,14 +59,26 @@ func TestRenderLoadAndValidate(t *testing.T) {
 				if cfg.Pipeline.Render.IncludeTimestamps == nil || *cfg.Pipeline.Render.IncludeTimestamps {
 					t.Fatalf("render.include_timestamps = %#v, want false", cfg.Pipeline.Render.IncludeTimestamps)
 				}
-				if !cfg.Pipeline.Render.IncludeSegmentIDs {
-					t.Fatalf("render.include_segment_ids = false, want true")
+				if cfg.Pipeline.Render.IncludeSegmentIDs == nil || !*cfg.Pipeline.Render.IncludeSegmentIDs {
+					t.Fatalf("render.include_segment_ids = %#v, want true", cfg.Pipeline.Render.IncludeSegmentIDs)
 				}
 				if !cfg.Pipeline.Render.IncludeMetadata {
 					t.Fatalf("render.include_metadata = false, want true")
 				}
 			},
 		},
+		{
+			name: "explicit segment ids false overrides default",
+			renderYAML: `render:
+  include_segment_ids: false
+`,
+			assert: func(t *testing.T, cfg *Config) {
+				t.Helper()
+				if cfg.Pipeline.Render.IncludeSegmentIDs == nil || *cfg.Pipeline.Render.IncludeSegmentIDs {
+					t.Fatalf("render.include_segment_ids = %#v, want false", cfg.Pipeline.Render.IncludeSegmentIDs)
+				}
+			},
+		},
 		{
 			name: "invalid render format fails",
 			renderYAML: `render:
diff --git a/internal/config/validate.go b/internal/config/validate.go
index fb3df42..c5b5d30 100644
--- a/internal/config/validate.go
+++ b/internal/config/validate.go
@@ -312,6 +312,9 @@ func validateRender(cfg *RenderConfig) error {
 	if cfg.IncludeTimestamps == nil {
 		return fmt.Errorf("pipeline.render.include_timestamps must be set (defaults should populate this)")
 	}
+	if cfg.IncludeSegmentIDs == nil {
+		return fmt.Errorf("pipeline.render.include_segment_ids must be set (defaults should populate this)")
+	}
 	format := strings.TrimSpace(cfg.Format)
 	if format != "markdown" {
 		return fmt.Errorf("pipeline.render.format must be markdown")
diff --git a/internal/stage/render.go b/internal/stage/render.go
index c2de8af..639f02a 100644
--- a/internal/stage/render.go
+++ b/internal/stage/render.go
@@ -69,7 +69,10 @@ func (renderStage) Run(ctx context.Context, env *Env, m *manifest.Manifest) (*St
 	}
 	title := resolveRenderTitle(renderCfg, env.Config.Session)
 	includeTimestamps := renderCfg.IncludeTimestamps == nil || *renderCfg.IncludeTimestamps
-	includeSegmentIDs := renderCfg.IncludeSegmentIDs
+	includeSegmentIDs := config.DefaultRenderSegmentIDs
+	if renderCfg.IncludeSegmentIDs != nil {
+		includeSegmentIDs = *renderCfg.IncludeSegmentIDs
+	}
 	includeMetadata := renderCfg.IncludeMetadata
 
 	meta := map[string]any{
@@ -237,11 +240,12 @@ func renderConfigOrDefault(cfg *config.RenderConfig) *config.RenderConfig {
 	}
 	enabled := true
 	includeTimestamps := true
+	includeSegmentIDs := config.DefaultRenderSegmentIDs
 	return &config.RenderConfig{
 		Enabled:           &enabled,
 		Format:            config.DefaultRenderFormat,
 		IncludeTimestamps: &includeTimestamps,
-		IncludeSegmentIDs: config.DefaultRenderSegmentIDs,
+		IncludeSegmentIDs: &includeSegmentIDs,
 		IncludeMetadata:   config.DefaultRenderMetadata,
 	}
 }
diff --git a/internal/stage/render_test.go b/internal/stage/render_test.go
index a2a5d8f..57d87c3 100644
--- a/internal/stage/render_test.go
+++ b/internal/stage/render_test.go
@@ -165,6 +165,7 @@ func setupRenderEnv(t *testing.T) (*Env, *manifest.Manifest, *seriatim.FakeRunne
 
 	enabled := true
 	includeTimestamps := true
+	includeSegmentIDs := false
 	seriatimReport := false
 	cfg := &config.Config{
 		PipelinePath: pipelinePath,
@@ -183,7 +184,7 @@ func setupRenderEnv(t *testing.T) (*Env, *manifest.Manifest, *seriatim.FakeRunne
 				Format:            "markdown",
 				Title:             "Pipeline Title",
 				IncludeTimestamps: &includeTimestamps,
-				IncludeSegmentIDs: false,
+				IncludeSegmentIDs: &includeSegmentIDs,
 				IncludeMetadata:   false,
 			},
 		},