diff --git a/codex-rs/analytics/src/analytics_client_tests.rs b/codex-rs/analytics/src/analytics_client_tests.rs
index 515fcc56379e..269d33326f72 100644
--- a/codex-rs/analytics/src/analytics_client_tests.rs
+++ b/codex-rs/analytics/src/analytics_client_tests.rs
@@ -303,10 +303,10 @@ fn sample_turn_completed_notification(
     })
 }
 
-fn sample_turn_resolved_config(turn_id: &str) -> TurnResolvedConfigFact {
+fn sample_turn_resolved_config(thread_id: &str, turn_id: &str) -> TurnResolvedConfigFact {
     TurnResolvedConfigFact {
         turn_id: turn_id.to_string(),
-        thread_id: "thread-2".to_string(),
+        thread_id: thread_id.to_string(),
         num_input_images: 1,
         submission_type: None,
         ephemeral: false,
@@ -419,6 +419,38 @@ async fn ingest_rejected_turn_steer(
         /*include_started*/ false, /*include_token_usage*/ false,
     )
     .await;
+    reducer
+        .ingest(
+            AnalyticsFact::Initialize {
+                connection_id: 8,
+                params: InitializeParams {
+                    client_info: ClientInfo {
+                        name: "codex-web".to_string(),
+                        title: None,
+                        version: "1.0.0".to_string(),
+                    },
+                    capabilities: None,
+                },
+                product_client_id: "codex-web".to_string(),
+                runtime: sample_runtime_metadata(),
+                rpc_transport: AppServerRpcTransport::Stdio,
+            },
+            out,
+        )
+        .await;
+    reducer
+        .ingest(
+            AnalyticsFact::ClientResponse {
+                connection_id: 8,
+                request_id: RequestId::Integer(6),
+                response: Box::new(sample_thread_resume_response(
+                    "thread-2", /*ephemeral*/ false, "gpt-5",
+                )),
+            },
+            out,
+        )
+        .await;
+    out.clear();
     reducer
         .ingest(
             AnalyticsFact::ClientRequest {
@@ -519,7 +551,7 @@ async fn ingest_turn_prerequisites(
         reducer
             .ingest(
                 AnalyticsFact::Custom(CustomAnalyticsFact::TurnResolvedConfig(Box::new(
-                    sample_turn_resolved_config("turn-2"),
+                    sample_turn_resolved_config("thread-2", "turn-2"),
                 ))),
                 out,
             )
@@ -1436,6 +1468,110 @@ async fn subagent_thread_started_publishes_without_initialize() {
     assert_eq!(payload[0]["event_params"]["subagent_source"], "review");
 }
 
+#[tokio::test]
+async fn subagent_thread_started_inherits_parent_connection_for_new_thread() {
+    let mut reducer = AnalyticsReducer::default();
+    let mut events = Vec::new();
+    let parent_thread_id =
+        codex_protocol::ThreadId::from_string("44444444-4444-4444-4444-444444444444")
+            .expect("valid parent thread id");
+    let parent_thread_id_string = parent_thread_id.to_string();
+
+    reducer
+        .ingest(
+            AnalyticsFact::Initialize {
+                connection_id: 7,
+                params: InitializeParams {
+                    client_info: ClientInfo {
+                        name: "parent-client".to_string(),
+                        title: None,
+                        version: "1.0.0".to_string(),
+                    },
+                    capabilities: None,
+                },
+                product_client_id: "parent-client".to_string(),
+                runtime: sample_runtime_metadata(),
+                rpc_transport: AppServerRpcTransport::Stdio,
+            },
+            &mut events,
+        )
+        .await;
+    reducer
+        .ingest(
+            AnalyticsFact::ClientResponse {
+                connection_id: 7,
+                request_id: RequestId::Integer(1),
+                response: Box::new(sample_thread_start_response(
+                    &parent_thread_id_string,
+                    /*ephemeral*/ false,
+                    "gpt-5",
+                )),
+            },
+            &mut events,
+        )
+        .await;
+
+    reducer
+        .ingest(
+            AnalyticsFact::Custom(CustomAnalyticsFact::SubAgentThreadStarted(
+                SubAgentThreadStartedInput {
+                    thread_id: "thread-review".to_string(),
+                    parent_thread_id: None,
+                    product_client_id: "parent-client".to_string(),
+                    client_name: "parent-client".to_string(),
+                    client_version: "1.0.0".to_string(),
+                    model: "gpt-5".to_string(),
+                    ephemeral: false,
+                    subagent_source: SubAgentSource::ThreadSpawn {
+                        parent_thread_id,
+                        depth: 1,
+                        agent_path: None,
+                        agent_nickname: None,
+                        agent_role: None,
+                    },
+                    created_at: 130,
+                },
+            )),
+            &mut events,
+        )
+        .await;
+
+    events.clear();
+    reducer
+        .ingest(
+            AnalyticsFact::Custom(CustomAnalyticsFact::Compaction(Box::new(
+                CodexCompactionEvent {
+                    thread_id: "thread-review".to_string(),
+                    turn_id: "turn-compact".to_string(),
+                    trigger: CompactionTrigger::Manual,
+                    reason: CompactionReason::UserRequested,
+                    implementation: CompactionImplementation::Responses,
+                    phase: CompactionPhase::StandaloneTurn,
+                    strategy: CompactionStrategy::Memento,
+                    status: CompactionStatus::Completed,
+                    error: None,
+                    active_context_tokens_before: 131_000,
+                    active_context_tokens_after: 64_000,
+                    started_at: 100,
+                    completed_at: 101,
+                    duration_ms: Some(1200),
+                },
+            ))),
+            &mut events,
+        )
+        .await;
+
+    let payload = serde_json::to_value(&events).expect("serialize events");
+    assert_eq!(
+        payload[0]["event_params"]["app_server_client"]["product_client_id"],
+        "parent-client"
+    );
+    assert_eq!(
+        payload[0]["event_params"]["parent_thread_id"],
+        "44444444-4444-4444-4444-444444444444"
+    );
+}
+
 #[test]
 fn plugin_used_event_serializes_expected_shape() {
     let tracking = TrackEventsContext {
@@ -2130,7 +2266,7 @@ async fn turn_start_error_response_discards_pending_start_request() {
     reducer
         .ingest(
             AnalyticsFact::Custom(CustomAnalyticsFact::TurnResolvedConfig(Box::new(
-                sample_turn_resolved_config("turn-2"),
+                sample_turn_resolved_config("thread-2", "turn-2"),
             ))),
             &mut out,
         )
diff --git a/codex-rs/analytics/src/reducer.rs b/codex-rs/analytics/src/reducer.rs
index 43da35c47c3e..b1dc822d4365 100644
--- a/codex-rs/analytics/src/reducer.rs
+++ b/codex-rs/analytics/src/reducer.rs
@@ -74,8 +74,7 @@ pub(crate) struct AnalyticsReducer {
     requests: HashMap<(u64, RequestId), RequestState>,
     turns: HashMap<String, TurnState>,
     connections: HashMap<u64, ConnectionState>,
-    thread_connections: HashMap<String, u64>,
-    thread_metadata: HashMap<String, ThreadMetadataState>,
+    threads: HashMap<String, ThreadAnalyticsState>,
 }
 
 struct ConnectionState {
@@ -83,6 +82,69 @@ struct ConnectionState {
     runtime: CodexRuntimeMetadata,
 }
 
+#[derive(Default)]
+struct ThreadAnalyticsState {
+    connection_id: Option<u64>,
+    metadata: Option<ThreadMetadataState>,
+}
+
+#[derive(Clone, Copy)]
+struct AnalyticsDropSite<'a> {
+    event_name: &'static str,
+    thread_id: &'a str,
+    turn_id: Option<&'a str>,
+    review_id: Option<&'a str>,
+    item_id: Option<&'a str>,
+}
+
+impl<'a> AnalyticsDropSite<'a> {
+    fn guardian(input: &'a GuardianReviewEventParams) -> Self {
+        Self {
+            event_name: "guardian",
+            thread_id: &input.thread_id,
+            turn_id: Some(&input.turn_id),
+            review_id: Some(&input.review_id),
+            item_id: None,
+        }
+    }
+
+    fn compaction(input: &'a CodexCompactionEvent) -> Self {
+        Self {
+            event_name: "compaction",
+            thread_id: &input.thread_id,
+            turn_id: Some(&input.turn_id),
+            review_id: None,
+            item_id: None,
+        }
+    }
+
+    fn turn_steer(thread_id: &'a str) -> Self {
+        Self {
+            event_name: "turn steer",
+            thread_id,
+            turn_id: None,
+            review_id: None,
+            item_id: None,
+        }
+    }
+
+    fn turn(thread_id: &'a str, turn_id: &'a str) -> Self {
+        Self {
+            event_name: "turn",
+            thread_id,
+            turn_id: Some(turn_id),
+            review_id: None,
+            item_id: None,
+        }
+    }
+}
+
+enum MissingAnalyticsContext {
+    ThreadConnection,
+    Connection { connection_id: u64 },
+    ThreadMetadata,
+}
+
 #[derive(Clone)]
 struct ThreadMetadataState {
     thread_source: Option<&'static str>,
@@ -274,6 +336,26 @@ impl AnalyticsReducer {
         input: SubAgentThreadStartedInput,
         out: &mut Vec<TrackEventRequest>,
     ) {
+        let parent_thread_id = input
+            .parent_thread_id
+            .clone()
+            .or_else(|| subagent_parent_thread_id(&input.subagent_source));
+        let parent_connection_id = parent_thread_id
+            .as_ref()
+            .and_then(|parent_thread_id| self.threads.get(parent_thread_id))
+            .and_then(|thread| thread.connection_id);
+        let thread_state = self.threads.entry(input.thread_id.clone()).or_default();
+        thread_state
+            .metadata
+            .get_or_insert_with(|| ThreadMetadataState {
+                thread_source: Some("subagent"),
+                initialization_mode: ThreadInitializationMode::New,
+                subagent_source: Some(subagent_source_name(&input.subagent_source)),
+                parent_thread_id,
+            });
+        if thread_state.connection_id.is_none() {
+            thread_state.connection_id = parent_connection_id;
+        }
         out.push(TrackEventRequest::ThreadInitialized(
             subagent_thread_started_event_request(input),
         ));
@@ -284,23 +366,9 @@ impl AnalyticsReducer {
         input: GuardianReviewEventParams,
         out: &mut Vec<TrackEventRequest>,
     ) {
-        let Some(connection_id) = self.thread_connections.get(&input.thread_id) else {
-            tracing::warn!(
-                thread_id = %input.thread_id,
-                turn_id = %input.turn_id,
-                review_id = %input.review_id,
-                "dropping guardian analytics event: missing thread connection metadata"
-            );
-            return;
-        };
-        let Some(connection_state) = self.connections.get(connection_id) else {
-            tracing::warn!(
-                thread_id = %input.thread_id,
-                turn_id = %input.turn_id,
-                review_id = %input.review_id,
-                connection_id,
-                "dropping guardian analytics event: missing connection metadata"
-            );
+        let Some(connection_state) =
+            self.thread_connection_or_warn(AnalyticsDropSite::guardian(&input))
+        else {
             return;
         };
         out.push(TrackEventRequest::GuardianReview(Box::new(
@@ -686,10 +754,13 @@ impl AnalyticsReducer {
         };
         let thread_metadata =
             ThreadMetadataState::from_thread_metadata(&thread_source, initialization_mode);
-        self.thread_connections
-            .insert(thread_id.clone(), connection_id);
-        self.thread_metadata
-            .insert(thread_id.clone(), thread_metadata.clone());
+        self.threads.insert(
+            thread_id.clone(),
+            ThreadAnalyticsState {
+                connection_id: Some(connection_id),
+                metadata: Some(thread_metadata.clone()),
+            },
+        );
         out.push(TrackEventRequest::ThreadInitialized(
             ThreadInitializedEvent {
                 event_type: "codex_thread_initialized",
@@ -710,29 +781,9 @@ impl AnalyticsReducer {
     }
 
     fn ingest_compaction(&mut self, input: CodexCompactionEvent, out: &mut Vec<TrackEventRequest>) {
-        let Some(connection_id) = self.thread_connections.get(&input.thread_id) else {
-            tracing::warn!(
-                thread_id = %input.thread_id,
-                turn_id = %input.turn_id,
-                "dropping compaction analytics event: missing thread connection metadata"
-            );
-            return;
-        };
-        let Some(connection_state) = self.connections.get(connection_id) else {
-            tracing::warn!(
-                thread_id = %input.thread_id,
-                turn_id = %input.turn_id,
-                connection_id,
-                "dropping compaction analytics event: missing connection metadata"
-            );
-            return;
-        };
-        let Some(thread_metadata) = self.thread_metadata.get(&input.thread_id) else {
-            tracing::warn!(
-                thread_id = %input.thread_id,
-                turn_id = %input.turn_id,
-                "dropping compaction analytics event: missing thread lifecycle metadata"
-            );
+        let Some((connection_state, thread_metadata)) =
+            self.thread_context_or_warn(AnalyticsDropSite::compaction(&input))
+        else {
             return;
         };
         out.push(TrackEventRequest::Compaction(Box::new(
@@ -787,11 +838,13 @@ impl AnalyticsReducer {
         let Some(connection_state) = self.connections.get(&connection_id) else {
             return;
         };
-        let Some(thread_metadata) = self.thread_metadata.get(&pending_request.thread_id) else {
-            tracing::warn!(
-                thread_id = %pending_request.thread_id,
-                "dropping turn steer analytics event: missing thread lifecycle metadata"
-            );
+        let drop_site = AnalyticsDropSite::turn_steer(&pending_request.thread_id);
+        let Some(thread_metadata) = self
+            .threads
+            .get(drop_site.thread_id)
+            .and_then(|thread| thread.metadata.as_ref())
+        else {
+            warn_missing_analytics_context(&drop_site, MissingAnalyticsContext::ThreadMetadata);
             return;
         };
         out.push(TrackEventRequest::TurnSteer(CodexTurnSteerEventRequest {
@@ -824,42 +877,34 @@ impl AnalyticsReducer {
         {
             return;
         }
-        let connection_metadata = turn_state
-            .connection_id
-            .and_then(|connection_id| self.connections.get(&connection_id))
-            .map(|connection_state| {
-                (
-                    connection_state.app_server_client.clone(),
-                    connection_state.runtime.clone(),
-                )
-            });
-        let Some((app_server_client, runtime)) = connection_metadata else {
-            if let Some(connection_id) = turn_state.connection_id {
-                tracing::warn!(
-                    turn_id,
-                    connection_id,
-                    "dropping turn analytics event: missing connection metadata"
-                );
-            }
+        let Some(thread_id) = turn_state.thread_id.as_ref() else {
             return;
         };
-        let Some(thread_id) = turn_state.thread_id.as_ref() else {
+        let Some(connection_id) = turn_state.connection_id else {
             return;
         };
-        let Some(thread_metadata) = self.thread_metadata.get(thread_id) else {
-            tracing::warn!(
-                thread_id,
-                turn_id,
-                "dropping turn analytics event: missing thread lifecycle metadata"
+        let Some(connection_state) = self.connections.get(&connection_id) else {
+            warn_missing_analytics_context(
+                &AnalyticsDropSite::turn(thread_id, turn_id),
+                MissingAnalyticsContext::Connection { connection_id },
             );
             return;
         };
+        let drop_site = AnalyticsDropSite::turn(thread_id, turn_id);
+        let Some(thread_metadata) = self
+            .threads
+            .get(drop_site.thread_id)
+            .and_then(|thread| thread.metadata.as_ref())
+        else {
+            warn_missing_analytics_context(&drop_site, MissingAnalyticsContext::ThreadMetadata);
+            return;
+        };
         out.push(TrackEventRequest::TurnEvent(Box::new(
             CodexTurnEventRequest {
                 event_type: "codex_turn_event",
                 event_params: codex_turn_event_params(
-                    app_server_client,
-                    runtime,
+                    connection_state.app_server_client.clone(),
+                    connection_state.runtime.clone(),
                     turn_id.to_string(),
                     turn_state,
                     thread_metadata,
@@ -868,6 +913,67 @@ impl AnalyticsReducer {
         )));
         self.turns.remove(turn_id);
     }
+
+    fn thread_connection_or_warn(
+        &self,
+        drop_site: AnalyticsDropSite<'_>,
+    ) -> Option<&ConnectionState> {
+        let Some(thread_state) = self.threads.get(drop_site.thread_id) else {
+            warn_missing_analytics_context(&drop_site, MissingAnalyticsContext::ThreadConnection);
+            return None;
+        };
+        let Some(connection_id) = thread_state.connection_id else {
+            warn_missing_analytics_context(&drop_site, MissingAnalyticsContext::ThreadConnection);
+            return None;
+        };
+        let Some(connection_state) = self.connections.get(&connection_id) else {
+            warn_missing_analytics_context(
+                &drop_site,
+                MissingAnalyticsContext::Connection { connection_id },
+            );
+            return None;
+        };
+        Some(connection_state)
+    }
+
+    fn thread_context_or_warn(
+        &self,
+        drop_site: AnalyticsDropSite<'_>,
+    ) -> Option<(&ConnectionState, &ThreadMetadataState)> {
+        let connection_state = self.thread_connection_or_warn(drop_site)?;
+        let Some(thread_metadata) = self
+            .threads
+            .get(drop_site.thread_id)
+            .and_then(|thread| thread.metadata.as_ref())
+        else {
+            warn_missing_analytics_context(&drop_site, MissingAnalyticsContext::ThreadMetadata);
+            return None;
+        };
+        Some((connection_state, thread_metadata))
+    }
+}
+
+fn warn_missing_analytics_context(
+    drop_site: &AnalyticsDropSite<'_>,
+    missing: MissingAnalyticsContext,
+) {
+    let (missing_context, connection_id) = match missing {
+        MissingAnalyticsContext::ThreadConnection => ("thread_connection", None),
+        MissingAnalyticsContext::Connection { connection_id } => {
+            ("connection", Some(connection_id))
+        }
+        MissingAnalyticsContext::ThreadMetadata => ("thread_metadata", None),
+    };
+    tracing::warn!(
+        thread_id = %drop_site.thread_id,
+        turn_id = ?drop_site.turn_id,
+        review_id = ?drop_site.review_id,
+        item_id = ?drop_site.item_id,
+        missing_context,
+        connection_id,
+        "dropping {} analytics event: missing analytics context",
+        drop_site.event_name
+    );
 }
 
 fn codex_turn_event_params(