Remove lead/worker provider (#7989)

Signed-off-by: Douwe Osinga <douwe@squareup.com>
Co-authored-by: Douwe Osinga <douwe@squareup.com>

crates/goose-cli/src/session/builder.rs

@@ -648,18 +648,8 @@ pub async fn build_session(session_config: SessionBuilderConfig) -> CliSession {
             process::exit(1);
         }
     };
-    let provider_for_display = Arc::clone(&new_provider);
-
-    if let Some(lead_worker) = new_provider.as_lead_worker() {
-        let (lead_model, worker_model) = lead_worker.get_model_info();
-        tracing::info!(
-            "🤖 Lead/Worker Mode Enabled: Lead model (first 3 turns): {}, Worker model (turn 4+): {}, Auto-fallback on failures: Enabled",
-            lead_model,
-            worker_model
-        );
-    } else {
-        tracing::info!("🤖 Using model: {}", resolved.model_name);
-    }
+    let provider_for_debug = Arc::clone(&new_provider);
+    tracing::info!("🤖 Using model: {}", resolved.model_name);
 
     agent
         .update_provider(new_provider, &session_id)
@@ -692,7 +682,7 @@ pub async fn build_session(session_config: SessionBuilderConfig) -> CliSession {
     let agent_ptr = resolve_and_load_extensions(
         agent,
         extensions_for_provider,
-        Arc::clone(&provider_for_display),
+        Arc::clone(&provider_for_debug),
         session_config.interactive,
         &session_id,
     )
@@ -732,7 +722,6 @@ pub async fn build_session(session_config: SessionBuilderConfig) -> CliSession {
             &resolved.provider_name,
             &resolved.model_name,
             &Some(session_id),
-            Some(&provider_for_display),
         );
     }
     session

crates/goose-cli/src/session/mod.rs

@@ -79,10 +79,6 @@ enum StreamEvent {
         #[serde(flatten)]
         data: NotificationData,
     },
-    ModelChange {
-        model: String,
-        mode: String,
-    },
     Error {
         error: String,
     },
@@ -1070,13 +1066,6 @@ impl CliSession {
                         Some(Ok(AgentEvent::HistoryReplaced(updated_conversation))) => {
                             self.messages = updated_conversation;
                         }
-                        Some(Ok(AgentEvent::ModelChange { model, mode })) => {
-                            if is_stream_json_mode {
-                                emit_stream_event(&StreamEvent::ModelChange { model: model.clone(), mode: mode.clone() });
-                            } else if self.debug {
-                                eprintln!("Model changed to {} in {} mode", model, mode);
-                            }
-                        }
                         Some(Err(e)) => {
                             handle_agent_error(&e, is_stream_json_mode);
                             cancel_token_clone.cancel();

crates/goose-cli/src/session/output.rs

@@ -17,7 +17,7 @@ use std::cell::RefCell;
 use std::collections::HashMap;
 use std::io::{Error, IsTerminal, Write};
 use std::path::Path;
-use std::sync::{Arc, LazyLock};
+use std::sync::LazyLock;
 use std::time::Duration;
 
 use super::streaming_buffer::MarkdownBuffer;
@@ -1251,7 +1251,6 @@ pub fn display_session_info(
     provider: &str,
     model: &str,
     session_id: &Option<String>,
-    provider_instance: Option<&Arc<dyn goose::providers::base::Provider>>,
 ) {
     set_terminal_title();
 
@@ -1263,16 +1262,7 @@ pub fn display_session_info(
         "new session"
     };
 
-    let model_display = if let Some(provider_inst) = provider_instance {
-        if let Some(lead_worker) = provider_inst.as_lead_worker() {
-            let (lead_model, worker_model) = lead_worker.get_model_info();
-            format!("{} → {}", lead_model, worker_model)
-        } else {
-            model.to_string()
-        }
-    } else {
-        model.to_string()
-    };
+    let model_display = model.to_string();
 
     let cwd_display = std::env::current_dir()
         .ok()