feat(tui): render initial config-options banner at session startup

nori-rs/tui/src/chatwidget/helpers.rs

@@ -75,6 +75,13 @@ impl ChatWidget {
                     ),
                 );
             }
+        } else if !next_snapshot.is_empty() {
+            self.add_to_history(
+                crate::nori::session_config_history::new_agent_options_initial_history_cell(
+                    self.bottom_pane.agent_display_name(),
+                    config_options,
+                ),
+            );
         }
 
         self.acp_config_option_snapshot = Some(next_snapshot);

nori-rs/tui/src/chatwidget/tests/part3.rs

@@ -469,10 +469,10 @@ fn session_config_update_history_shows_only_changed_values_after_baseline() {
             ],
         },
     ));
-    assert!(
-        drain_insert_history(&mut rx).is_empty(),
-        "the first config snapshot should establish a baseline without history noise"
-    );
+    // Drain (and discard) the initial-snapshot banner so the snapshot below
+    // captures only the subsequent change-diff cell. The banner is covered
+    // by `session_config_update_history_renders_startup_banner_on_first_snapshot`.
+    let _ = drain_insert_history(&mut rx);
 
     chat.handle_client_event(nori_protocol::ClientEvent::SessionConfigUpdate(
         nori_protocol::SessionConfigUpdate {
@@ -509,6 +509,46 @@ fn session_config_update_history_shows_only_changed_values_after_baseline() {
     assert_snapshot!("session_config_update_changed_values_history", rendered);
 }
 
+#[test]
+fn session_config_update_history_renders_startup_banner_on_first_snapshot() {
+    let (mut chat, mut rx, _op_rx) = make_chatwidget_manual();
+    chat.set_agent("claude-code");
+
+    chat.handle_client_event(nori_protocol::ClientEvent::SessionConfigUpdate(
+        nori_protocol::SessionConfigUpdate {
+            config_options: vec![
+                select_config_option(
+                    "mode",
+                    "Mode",
+                    "default",
+                    &[("default", "Default"), ("plan", "Plan")],
+                ),
+                select_config_option(
+                    "model",
+                    "Model",
+                    "opus-4-6",
+                    &[("opus-4-6", "Opus 4.6"), ("sonnet-4-6", "Sonnet 4.6")],
+                ),
+                select_config_option(
+                    "effort",
+                    "Effort",
+                    "medium",
+                    &[("medium", "Medium"), ("high", "High")],
+                ),
+            ],
+        },
+    ));
+
+    let cells = drain_insert_history(&mut rx);
+    let rendered = cells
+        .iter()
+        .map(|lines| lines_to_single_string(lines))
+        .collect::<Vec<_>>()
+        .join("\n");
+
+    assert_snapshot!("session_config_update_startup_banner", rendered);
+}
+
 #[test]
 fn session_config_set_history_uses_final_agent_named_message() {
     let (mut chat, mut rx, _op_rx) = make_chatwidget_manual();

nori-rs/tui/src/chatwidget/tests/snapshots/nori_tui__chatwidget__tests__part3__session_config_update_startup_banner.snap

@@ -0,0 +1,5 @@
+---
+source: tui/src/chatwidget/tests/part3.rs
+expression: rendered
+---
+• Claude Code options: Mode=Default, Model=Opus 4.6, Effort=Medium (/config to change)

nori-rs/tui/src/nori/session_config_history.rs

@@ -39,6 +39,33 @@ pub(crate) fn changed_values(
         .collect()
 }
 
+/// Initial-snapshot banner shown the first time the agent announces its
+/// session config options. Lists every option's current value and surfaces
+/// the `/config` affordance so the user knows how to change them.
+pub(crate) fn new_agent_options_initial_history_cell(
+    agent_display_name: &str,
+    config_options: &[acp::SessionConfigOption],
+) -> PlainHistoryCell {
+    let agent_display_name = if agent_display_name.is_empty() {
+        "Agent"
+    } else {
+        agent_display_name
+    };
+    let values: Vec<SessionConfigDisplayValue> =
+        config_options.iter().filter_map(display_value).collect();
+
+    let mut line = vec!["• ".dim(), format!("{agent_display_name} options: ").into()];
+    for (index, value) in values.iter().enumerate() {
+        if index > 0 {
+            line.push(", ".into());
+        }
+        line.push(format!("{}={}", value.name, value.value).cyan().bold());
+    }
+    line.push(" (/config to change)".dim());
+
+    PlainHistoryCell::new(vec![Line::from(line)])
+}
+
 pub(crate) fn new_agent_options_history_cell(
     agent_display_name: &str,
     changes: &[SessionConfigDisplayValue],