diff --git a/bt-daemon/src/translate/codex.rs b/bt-daemon/src/translate/codex.rs
index adc93c9..a496b57 100644
--- a/bt-daemon/src/translate/codex.rs
+++ b/bt-daemon/src/translate/codex.rs
@@ -280,6 +280,7 @@ impl AgentTranslator for CodexTranslator {
                 if let Some(hook) = decode::<SessionStartHook>(payload) {
                     self.session_source = hook.source;
                     self.permission_mode = hook.permission_mode;
+                    self.update_open_main_root_source(&mut ops);
                 }
             }
             "SubagentStart" => {
@@ -430,6 +431,34 @@ impl CodexTranslator {
         );
     }
 
+    fn update_open_main_root_source(&self, ops: &mut Vec<SpanOp>) {
+        let Some(source) = &self.session_source else {
+            return;
+        };
+        if !self.root_opened {
+            return;
+        }
+        let model = self
+            .main_path
+            .as_ref()
+            .and_then(|path| self.scopes.get(path))
+            .and_then(|scope| scope.model.clone());
+        ops.push(SpanOp::Merge(SpanRow {
+            span_id: self.root_span_id.clone(),
+            root_span_id: self.root_span_id.clone(),
+            input: Some(json!({
+                "model": model,
+                "cwd": self.root_cwd,
+                "source": source,
+            })),
+            metadata: Some(json!({
+                "source": "codex",
+                "session_source": source,
+            })),
+            ..Default::default()
+        }));
+    }
+
     fn record_compaction_trigger(&mut self, hook: CompactHook, ops: &mut Vec<SpanOp>) {
         let turn_id = hook.turn_id;
         let trigger = hook.trigger.unwrap_or_else(|| "manual".to_string());
@@ -594,20 +623,26 @@ impl CodexTranslator {
                         let model_turn_id = context.turn_id;
                         scope.model = Some(m.clone());
                         if scope.root_created {
-                            let input = if scope.kind == ScopeKind::Main {
-                                json!({
-                                    "model": m,
-                                    "cwd": self.root_cwd,
-                                    "source": self.session_source,
-                                })
+                            let (input, metadata) = if scope.kind == ScopeKind::Main {
+                                (
+                                    json!({
+                                        "model": m,
+                                        "cwd": self.root_cwd,
+                                        "source": self.session_source,
+                                    }),
+                                    json!({
+                                        "model": m,
+                                        "source": "codex",
+                                    }),
+                                )
                             } else {
-                                json!({ "model": m })
+                                (json!({ "model": m }), json!({ "model": m }))
                             };
                             ops.push(SpanOp::Merge(SpanRow {
                                 span_id: scope.turn_parent_span_id.clone(),
                                 root_span_id: self.root_span_id.clone(),
                                 input: Some(input),
-                                metadata: Some(json!({ "model": m })),
+                                metadata: Some(metadata),
                                 ..Default::default()
                             }));
                         }
@@ -685,9 +720,8 @@ impl CodexTranslator {
                         );
                     }
                 }
-                // `source` identifies the agent consistently across all coding-agent
-                // integrations. Codex's SessionStart source (for example, startup or
-                // resume) describes how this session began, so keep it separately.
+                // `source` is the stable integration identity used to classify
+                // traces. The native SessionStart lifecycle source is separate.
                 md.insert("source".into(), json!("codex"));
                 if let Some(session_source) = &self.session_source {
                     md.insert("session_source".into(), json!(session_source));
diff --git a/bt-daemon/tests/codex_translator.rs b/bt-daemon/tests/codex_translator.rs
index 6d63d9c..c094db2 100644
--- a/bt-daemon/tests/codex_translator.rs
+++ b/bt-daemon/tests/codex_translator.rs
@@ -267,6 +267,72 @@ fn codex_happy_path_builds_session_turn_llm_tool_tree() {
     );
 }
 
+#[test]
+fn codex_root_preserves_canonical_source_across_lifecycle_events() {
+    let tmp = tempfile::tempdir().unwrap();
+
+    for source in ["startup", "resume", "compact"] {
+        let transcript = tmp.path().join(format!("{source}.jsonl"));
+        append(
+            &transcript,
+            json!({ "timestamp": "2026-01-01T00:00:01Z", "type": "session_meta",
+                    "payload": { "id": "session-1", "cwd": "/x/app" } }),
+        );
+        append(
+            &transcript,
+            json!({ "timestamp": "2026-01-01T00:00:02Z", "type": "turn_context",
+                    "payload": { "model": "gpt-5.5" } }),
+        );
+        let session_id = format!("lifecycle-{source}");
+        let registry = Registry::default_agents();
+        let mut translator = registry.create("codex", &session_id);
+        let ctx = SessionCtx {
+            session_id: session_id.clone(),
+            config: None,
+        };
+        let mut ops = translator
+            .handle(
+                &envelope(
+                    &session_id,
+                    "SessionStart",
+                    transcript.to_str().unwrap(),
+                    json!({ "source": "startup" }),
+                ),
+                &ctx,
+            )
+            .unwrap();
+
+        if source != "startup" {
+            // A resumed or compacted session can exit before writing another
+            // model-bearing turn_context record.
+            ops.extend(
+                translator
+                    .handle(
+                        &envelope(
+                            &session_id,
+                            "SessionStart",
+                            transcript.to_str().unwrap(),
+                            json!({ "source": source }),
+                        ),
+                        &ctx,
+                    )
+                    .unwrap(),
+            );
+        }
+
+        let rows = reduce(ops);
+        let root = find(&rows, SpanType::Task, "codex: app");
+        assert_eq!(root.input.as_ref().unwrap()["source"], json!(source));
+        assert_eq!(root.input.as_ref().unwrap()["model"], json!("gpt-5.5"));
+        assert_eq!(root.input.as_ref().unwrap()["cwd"], json!("/x/app"));
+        assert_eq!(root.metadata.as_ref().unwrap()["source"], json!("codex"));
+        assert_eq!(
+            root.metadata.as_ref().unwrap()["session_source"],
+            json!(source)
+        );
+    }
+}
+
 #[test]
 fn codex_trailing_injected_user_row_does_not_replace_hook_prompt() {
     let tmp = tempfile::tempdir().unwrap();