diff --git a/codex-rs/core/src/codex.rs b/codex-rs/core/src/codex.rs
index 3a8faac441..0036cd2563 100644
--- a/codex-rs/core/src/codex.rs
+++ b/codex-rs/core/src/codex.rs
@@ -2570,11 +2570,13 @@ impl Session {
         .await
     }
 
+    /// `maybe_user_input` is only consulted for explicit plugin mentions on this turn.
+    /// Pass `None` when no raw current-turn user input is available.
     async fn build_settings_update_items(
         &self,
         reference_context_item: Option<&TurnContextItem>,
         current_context: &TurnContext,
-        additional_developer_sections: Vec<String>,
+        maybe_user_input: Option<&[UserInput]>,
     ) -> Vec<ResponseItem> {
         // TODO: Make context updates a pure diff of persisted previous/current TurnContextItem
         // state so replay/backtracking is deterministic. Runtime inputs that affect model-visible
@@ -2586,6 +2588,9 @@ impl Session {
         };
         let shell = self.user_shell();
         let exec_policy = self.services.exec_policy.current();
+        let additional_developer_sections = self
+            .build_explicit_plugin_developer_sections(current_context, maybe_user_input)
+            .await;
         crate::context_manager::updates::build_settings_update_items(
             reference_context_item,
             previous_turn_settings.as_ref(),
@@ -2597,6 +2602,47 @@ impl Session {
         )
     }
 
+    /// `maybe_user_input` is only used to derive explicit plugin-mention guidance for this turn.
+    /// When the raw user input is unavailable, pass `None` and no turn-local plugin guidance will
+    /// be added to the canonical developer envelope.
+    async fn build_explicit_plugin_developer_sections(
+        &self,
+        turn_context: &TurnContext,
+        maybe_user_input: Option<&[UserInput]>,
+    ) -> Vec<String> {
+        let Some(user_input) = maybe_user_input else {
+            return Vec::new();
+        };
+
+        let loaded_plugins = self
+            .services
+            .plugins_manager
+            .plugins_for_config(&turn_context.config);
+        let mentioned_plugins =
+            collect_explicit_plugin_mentions(user_input, loaded_plugins.capability_summaries());
+        if mentioned_plugins.is_empty() {
+            return Vec::new();
+        }
+
+        let mcp_tools = self
+            .services
+            .mcp_connection_manager
+            .read()
+            .await
+            .list_all_tools()
+            .await;
+        let available_connectors = if turn_context.apps_enabled() {
+            let connectors = connectors::merge_plugin_apps_with_accessible(
+                loaded_plugins.effective_apps(),
+                connectors::accessible_connectors_from_mcp_tools(&mcp_tools),
+            );
+            connectors::with_app_enabled_state(connectors, &turn_context.config)
+        } else {
+            Vec::new()
+        };
+        build_plugin_developer_sections(&mentioned_plugins, &mcp_tools, &available_connectors)
+    }
+
     /// Persist the event to rollout and send it to clients.
     pub(crate) async fn send_event(&self, turn_context: &TurnContext, msg: EventMsg) {
         let legacy_source = msg.clone();
@@ -3433,10 +3479,12 @@ impl Session {
         }
     }
 
+    /// `maybe_user_input` is only consulted for explicit plugin mentions on this turn.
+    /// Pass `None` when no raw current-turn user input is available.
     pub(crate) async fn build_initial_context(
         &self,
         turn_context: &TurnContext,
-        additional_developer_sections: Vec<String>,
+        maybe_user_input: Option<&[UserInput]>,
     ) -> Vec<ResponseItem> {
         let mut developer_sections = Vec::<String>::with_capacity(8);
         let mut contextual_user_sections = Vec::<String>::with_capacity(2);
@@ -3557,7 +3605,10 @@ impl Session {
         {
             developer_sections.push(plugin_section);
         }
-        developer_sections.extend(additional_developer_sections);
+        developer_sections.extend(
+            self.build_explicit_plugin_developer_sections(turn_context, maybe_user_input)
+                .await,
+        );
         if turn_context.features.enabled(Feature::CodexGitCommit)
             && let Some(commit_message_instruction) = commit_message_trailer_instruction(
                 turn_context.config.commit_attribution.as_deref(),
@@ -3645,39 +3696,27 @@ impl Session {
     /// Mid-turn compaction is the other path that can re-establish that baseline when it
     /// reinjects full initial context into replacement history. Other non-regular tasks
     /// intentionally do not update the baseline.
+    ///
+    /// `maybe_user_input` is only used to derive explicit plugin-mention guidance for the
+    /// canonical developer envelope on this turn.
     pub(crate) async fn record_context_updates_and_set_reference_context_item(
         &self,
         turn_context: &TurnContext,
-    ) {
-        self.record_context_updates_with_additional_developer_sections(
-            turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
-        .await;
-    }
-
-    // Some turn-local guidance, such as explicit plugin mention hints, belongs in the canonical
-    // pre-user developer message for the current turn but should not become durable
-    // `TurnContextItem` state. Thread those sections into the context builders here so they share
-    // the standard developer envelope without affecting the persisted diff baseline.
-    async fn record_context_updates_with_additional_developer_sections(
-        &self,
-        turn_context: &TurnContext,
-        additional_developer_sections: Vec<String>,
+        maybe_user_input: Option<&[UserInput]>,
     ) {
         let reference_context_item = {
             let state = self.state.lock().await;
             state.reference_context_item()
         };
         let context_items = if reference_context_item.is_none() {
-            self.build_initial_context(turn_context, additional_developer_sections)
+            self.build_initial_context(turn_context, maybe_user_input)
                 .await
         } else {
             // Steady-state path: append only context diffs to minimize token overhead.
             self.build_settings_update_items(
                 reference_context_item.as_ref(),
                 turn_context,
-                additional_developer_sections,
+                maybe_user_input,
             )
             .await
         };
@@ -5557,7 +5596,8 @@ pub(crate) async fn run_turn(
         .plugins_manager
         .plugins_for_config(&turn_context.config);
     // Structured plugin:// mentions are resolved from the current session's
-    // enabled plugins, then converted into turn-scoped guidance below.
+    // enabled plugins here for telemetry/tool selection; the canonical context
+    // builders derive any explicit plugin guidance from `maybe_user_input`.
     let mentioned_plugins =
         collect_explicit_plugin_mentions(&input, loaded_plugins.capability_summaries());
     let mcp_tools = if turn_context.apps_enabled() || !mentioned_plugins.is_empty() {
@@ -5643,23 +5683,16 @@ pub(crate) async fn run_turn(
             .await;
     }
 
-    let plugin_developer_sections =
-        build_plugin_developer_sections(&mentioned_plugins, &mcp_tools, &available_connectors);
     let mentioned_plugin_metadata = mentioned_plugins
         .iter()
         .filter_map(crate::plugins::PluginCapabilitySummary::telemetry_metadata)
         .collect::<Vec<_>>();
 
-    if plugin_developer_sections.is_empty() {
-        sess.record_context_updates_and_set_reference_context_item(turn_context.as_ref())
-            .await;
-    } else {
-        sess.record_context_updates_with_additional_developer_sections(
-            turn_context.as_ref(),
-            plugin_developer_sections,
-        )
-        .await;
-    }
+    sess.record_context_updates_and_set_reference_context_item(
+        turn_context.as_ref(),
+        /*maybe_user_input*/ Some(&input),
+    )
+    .await;
 
     let mut explicitly_enabled_connectors = collect_explicit_app_ids(&input);
     explicitly_enabled_connectors.extend(collect_explicit_app_ids_from_skill_items(
diff --git a/codex-rs/core/src/codex_tests.rs b/codex-rs/core/src/codex_tests.rs
index c7d29ea9f7..a588f5ddb1 100644
--- a/codex-rs/core/src/codex_tests.rs
+++ b/codex-rs/core/src/codex_tests.rs
@@ -957,21 +957,24 @@ async fn resumed_history_injects_initial_context_on_first_context_update_only()
     assert_eq!(expected, history_before_seed.raw_items());
 
     session
-        .record_context_updates_and_set_reference_context_item(&turn_context)
+        .record_context_updates_and_set_reference_context_item(
+            &turn_context,
+            /*maybe_user_input*/ None,
+        )
         .await;
     expected.extend(
         session
-            .build_initial_context(
-                &turn_context,
-                /*additional_developer_sections*/ Vec::new(),
-            )
+            .build_initial_context(&turn_context, /*maybe_user_input*/ None)
             .await,
     );
     let history_after_seed = session.clone_history().await;
     assert_eq!(expected, history_after_seed.raw_items());
 
     session
-        .record_context_updates_and_set_reference_context_item(&turn_context)
+        .record_context_updates_and_set_reference_context_item(
+            &turn_context,
+            /*maybe_user_input*/ None,
+        )
         .await;
     let history_after_second_seed = session.clone_history().await;
     assert_eq!(
@@ -1346,10 +1349,7 @@ async fn thread_rollback_drops_last_turn_from_history() {
     let rollout_path = attach_rollout_recorder(&sess).await;
 
     let initial_context = sess
-        .build_initial_context(
-            tc.as_ref(),
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(tc.as_ref(), /*maybe_user_input*/ None)
         .await;
     let turn_1 = vec![
         user_message("turn 1 user"),
@@ -1415,10 +1415,7 @@ async fn thread_rollback_clears_history_when_num_turns_exceeds_existing_turns()
     attach_rollout_recorder(&sess).await;
 
     let initial_context = sess
-        .build_initial_context(
-            tc.as_ref(),
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(tc.as_ref(), /*maybe_user_input*/ None)
         .await;
     let turn_1 = vec![user_message("turn 1 user")];
     let mut full_history = Vec::new();
@@ -1446,10 +1443,7 @@ async fn thread_rollback_fails_without_persisted_rollout_path() {
     let (sess, tc, rx) = make_session_and_context_with_rx().await;
 
     let initial_context = sess
-        .build_initial_context(
-            tc.as_ref(),
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(tc.as_ref(), /*maybe_user_input*/ None)
         .await;
     sess.record_into_history(&initial_context, tc.as_ref())
         .await;
@@ -1768,10 +1762,7 @@ async fn thread_rollback_fails_when_turn_in_progress() {
     let (sess, tc, rx) = make_session_and_context_with_rx().await;
 
     let initial_context = sess
-        .build_initial_context(
-            tc.as_ref(),
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(tc.as_ref(), /*maybe_user_input*/ None)
         .await;
     sess.record_into_history(&initial_context, tc.as_ref())
         .await;
@@ -1794,10 +1785,7 @@ async fn thread_rollback_fails_when_num_turns_is_zero() {
     let (sess, tc, rx) = make_session_and_context_with_rx().await;
 
     let initial_context = sess
-        .build_initial_context(
-            tc.as_ref(),
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(tc.as_ref(), /*maybe_user_input*/ None)
         .await;
     sess.record_into_history(&initial_context, tc.as_ref())
         .await;
@@ -3734,7 +3722,7 @@ async fn build_settings_update_items_emits_environment_item_for_network_changes(
         .build_settings_update_items(
             Some(&reference_context_item),
             &current_context,
-            /*additional_developer_sections*/ Vec::new(),
+            /*maybe_user_input*/ None,
         )
         .await;
 
@@ -3773,7 +3761,7 @@ async fn build_settings_update_items_emits_environment_item_for_time_changes() {
         .build_settings_update_items(
             Some(&reference_context_item),
             &current_context,
-            /*additional_developer_sections*/ Vec::new(),
+            /*maybe_user_input*/ None,
         )
         .await;
 
@@ -3809,7 +3797,7 @@ async fn build_settings_update_items_emits_realtime_start_when_session_becomes_l
         .build_settings_update_items(
             Some(&previous_context.to_turn_context_item()),
             &current_context,
-            /*additional_developer_sections*/ Vec::new(),
+            /*maybe_user_input*/ None,
         )
         .await;
 
@@ -3838,7 +3826,7 @@ async fn build_settings_update_items_emits_realtime_end_when_session_stops_being
         .build_settings_update_items(
             Some(&previous_context.to_turn_context_item()),
             &current_context,
-            /*additional_developer_sections*/ Vec::new(),
+            /*maybe_user_input*/ None,
         )
         .await;
 
@@ -3875,7 +3863,7 @@ async fn build_settings_update_items_uses_previous_turn_settings_for_realtime_en
         .build_settings_update_items(
             Some(&previous_context_item),
             &current_context,
-            /*additional_developer_sections*/ Vec::new(),
+            /*maybe_user_input*/ None,
         )
         .await;
 
@@ -3894,10 +3882,7 @@ async fn build_initial_context_uses_previous_realtime_state() {
     turn_context.realtime_active = true;
 
     let initial_context = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
     let developer_texts = developer_input_texts(&initial_context);
     assert!(
@@ -3913,10 +3898,7 @@ async fn build_initial_context_uses_previous_realtime_state() {
         state.set_reference_context_item(Some(previous_context_item));
     }
     let resumed_context = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
     let resumed_developer_texts = developer_input_texts(&resumed_context);
     assert!(
@@ -3943,10 +3925,7 @@ async fn build_initial_context_omits_default_image_save_location_with_image_hist
         .await;
 
     let initial_context = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
     let developer_texts = developer_input_texts(&initial_context);
     assert!(
@@ -3962,10 +3941,7 @@ async fn build_initial_context_omits_default_image_save_location_without_image_h
     let (session, turn_context) = make_session_and_context().await;
 
     let initial_context = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
     let developer_texts = developer_input_texts(&initial_context);
 
@@ -4080,10 +4056,7 @@ async fn build_initial_context_uses_previous_turn_settings_for_realtime_end() {
         .set_previous_turn_settings(Some(previous_turn_settings))
         .await;
     let initial_context = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
     let developer_texts = developer_input_texts(&initial_context);
     assert!(
@@ -4107,10 +4080,7 @@ async fn build_initial_context_restates_realtime_start_when_reference_context_is
         .set_previous_turn_settings(Some(previous_turn_settings))
         .await;
     let initial_context = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
     let developer_texts = developer_input_texts(&initial_context);
     assert!(
@@ -4126,14 +4096,14 @@ async fn record_context_updates_and_set_reference_context_item_injects_full_cont
  {
     let (session, turn_context) = make_session_and_context().await;
     session
-        .record_context_updates_and_set_reference_context_item(&turn_context)
+        .record_context_updates_and_set_reference_context_item(
+            &turn_context,
+            /*maybe_user_input*/ None,
+        )
         .await;
     let history = session.clone_history().await;
     let initial_context = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
     assert_eq!(history.raw_items().to_vec(), initial_context);
 
@@ -4162,7 +4132,10 @@ async fn record_context_updates_and_set_reference_context_item_reinjects_full_co
         .record_into_history(std::slice::from_ref(&compacted_summary), &turn_context)
         .await;
     session
-        .record_context_updates_and_set_reference_context_item(&turn_context)
+        .record_context_updates_and_set_reference_context_item(
+            &turn_context,
+            /*maybe_user_input*/ None,
+        )
         .await;
     {
         let mut state = session.state.lock().await;
@@ -4173,17 +4146,17 @@ async fn record_context_updates_and_set_reference_context_item_reinjects_full_co
         .await;
 
     session
-        .record_context_updates_and_set_reference_context_item(&turn_context)
+        .record_context_updates_and_set_reference_context_item(
+            &turn_context,
+            /*maybe_user_input*/ None,
+        )
         .await;
 
     let history = session.clone_history().await;
     let mut expected_history = vec![compacted_summary];
     expected_history.extend(
         session
-            .build_initial_context(
-                &turn_context,
-                /*additional_developer_sections*/ Vec::new(),
-            )
+            .build_initial_context(&turn_context, /*maybe_user_input*/ None)
             .await,
     );
     assert_eq!(history.raw_items().to_vec(), expected_history);
@@ -4232,13 +4205,16 @@ async fn record_context_updates_and_set_reference_context_item_persists_baseline
         .build_settings_update_items(
             Some(&previous_context_item),
             &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
+            /*maybe_user_input*/ None,
         )
         .await;
     assert_eq!(update_items, Vec::new());
 
     session
-        .record_context_updates_and_set_reference_context_item(&turn_context)
+        .record_context_updates_and_set_reference_context_item(
+            &turn_context,
+            /*maybe_user_input*/ None,
+        )
         .await;
 
     assert_eq!(
@@ -4284,10 +4260,7 @@ async fn build_initial_context_prepends_model_switch_message() {
         .set_previous_turn_settings(Some(previous_turn_settings))
         .await;
     let initial_context = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
 
     let ResponseItem::Message { role, content, .. } = &initial_context[0] else {
@@ -4356,7 +4329,10 @@ async fn record_context_updates_and_set_reference_context_item_persists_full_rei
         }))
         .await;
     session
-        .record_context_updates_and_set_reference_context_item(&turn_context)
+        .record_context_updates_and_set_reference_context_item(
+            &turn_context,
+            /*maybe_user_input*/ None,
+        )
         .await;
     session.ensure_rollout_materialized().await;
     session.flush_rollout().await;
@@ -4969,10 +4945,7 @@ async fn sample_rollout(
     // personality_spec) matches reconstruction.
     let reconstruction_turn = session.new_default_turn().await;
     let mut initial_context = session
-        .build_initial_context(
-            reconstruction_turn.as_ref(),
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(reconstruction_turn.as_ref(), /*maybe_user_input*/ None)
         .await;
     // Ensure personality_spec is present when Personality is enabled, so expected matches
     // what reconstruction produces (build_initial_context may omit it when baked into model).
diff --git a/codex-rs/core/src/compact.rs b/codex-rs/core/src/compact.rs
index 70958ef659..f03455e341 100644
--- a/codex-rs/core/src/compact.rs
+++ b/codex-rs/core/src/compact.rs
@@ -201,10 +201,7 @@ async fn run_compact_task_inner(
         InitialContextInjection::BeforeLastUserMessage
     ) {
         let initial_context = sess
-            .build_initial_context(
-                turn_context.as_ref(),
-                /*additional_developer_sections*/ Vec::new(),
-            )
+            .build_initial_context(turn_context.as_ref(), /*maybe_user_input*/ None)
             .await;
         new_history =
             insert_initial_context_before_last_real_user_or_summary(new_history, initial_context);
diff --git a/codex-rs/core/src/compact_remote.rs b/codex-rs/core/src/compact_remote.rs
index c24331292f..255f163874 100644
--- a/codex-rs/core/src/compact_remote.rs
+++ b/codex-rs/core/src/compact_remote.rs
@@ -178,11 +178,8 @@ pub(crate) async fn process_compacted_history(
         initial_context_injection,
         InitialContextInjection::BeforeLastUserMessage
     ) {
-        sess.build_initial_context(
-            turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
-        .await
+        sess.build_initial_context(turn_context, /*maybe_user_input*/ None)
+            .await
     } else {
         Vec::new()
     };
diff --git a/codex-rs/core/src/compact_tests.rs b/codex-rs/core/src/compact_tests.rs
index 1af4bc4991..628e52989a 100644
--- a/codex-rs/core/src/compact_tests.rs
+++ b/codex-rs/core/src/compact_tests.rs
@@ -10,10 +10,7 @@ async fn process_compacted_history_with_test_session(
         .set_previous_turn_settings(previous_turn_settings.cloned())
         .await;
     let initial_context = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
     let refreshed = crate::compact_remote::process_compacted_history(
         &session,
diff --git a/codex-rs/core/src/thread_manager_tests.rs b/codex-rs/core/src/thread_manager_tests.rs
index 09b99b852d..d124119b98 100644
--- a/codex-rs/core/src/thread_manager_tests.rs
+++ b/codex-rs/core/src/thread_manager_tests.rs
@@ -196,10 +196,7 @@ fn out_of_range_truncation_drops_pre_user_active_turn_prefix() {
 async fn ignores_session_prefix_messages_when_truncating() {
     let (session, turn_context) = make_session_and_context().await;
     let mut items = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
     items.push(user_msg("feature request"));
     items.push(assistant_msg("ack"));
diff --git a/codex-rs/core/src/thread_rollout_truncation_tests.rs b/codex-rs/core/src/thread_rollout_truncation_tests.rs
index 5bb14cb2f8..9e3f09d7e3 100644
--- a/codex-rs/core/src/thread_rollout_truncation_tests.rs
+++ b/codex-rs/core/src/thread_rollout_truncation_tests.rs
@@ -125,10 +125,7 @@ fn truncates_rollout_from_start_applies_thread_rollback_markers() {
 async fn ignores_session_prefix_messages_when_truncating_rollout_from_start() {
     let (session, turn_context) = make_session_and_context().await;
     let mut items = session
-        .build_initial_context(
-            &turn_context,
-            /*additional_developer_sections*/ Vec::new(),
-        )
+        .build_initial_context(&turn_context, /*maybe_user_input*/ None)
         .await;
     items.push(user_msg("feature request"));
     items.push(assistant_msg("ack"));