diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index 707fd9d430..11138fdc8a 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -2055,7 +2055,9 @@ dependencies = [
  "codex-protocol",
  "codex-utils-absolute-path",
  "notify",
+ "pretty_assertions",
  "regex-lite",
+ "reqwest",
  "serde_json",
  "shlex",
  "tempfile",
diff --git a/codex-rs/app-server-protocol/src/protocol/v2.rs b/codex-rs/app-server-protocol/src/protocol/v2.rs
index 05362b204e..4f6cfaa8ed 100644
--- a/codex-rs/app-server-protocol/src/protocol/v2.rs
+++ b/codex-rs/app-server-protocol/src/protocol/v2.rs
@@ -209,13 +209,26 @@ v2_enum_from_core!(
 );
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
-#[serde(rename_all = "camelCase")]
+#[serde(tag = "type", rename_all = "camelCase")]
+#[ts(tag = "type")]
 #[ts(export_to = "v2/")]
 pub enum ConfigLayerName {
-    Mdm,
-    System,
-    SessionFlags,
-    User,
+    /// Managed preferences layer delivered by MDM (macOS only).
+    #[serde(rename_all = "camelCase")]
+    #[ts(rename_all = "camelCase")]
+    Mdm { domain: String, key: String },
+    /// Managed config layer from a file (usually `managed_config.toml`).
+    #[serde(rename_all = "camelCase")]
+    #[ts(rename_all = "camelCase")]
+    System { file: AbsolutePathBuf },
+    /// Session-layer overrides supplied via `-c`/`--config`.
+    #[serde(rename_all = "camelCase")]
+    #[ts(rename_all = "camelCase")]
+    SessionFlags { override_keys: Vec<String> },
+    /// User config layer from a file (usually `config.toml`).
+    #[serde(rename_all = "camelCase")]
+    #[ts(rename_all = "camelCase")]
+    User { file: AbsolutePathBuf },
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default, JsonSchema, TS)]
@@ -289,7 +302,6 @@ pub struct Config {
 #[ts(export_to = "v2/")]
 pub struct ConfigLayerMetadata {
     pub name: ConfigLayerName,
-    pub source: String,
     pub version: String,
 }
 
@@ -298,7 +310,6 @@ pub struct ConfigLayerMetadata {
 #[ts(export_to = "v2/")]
 pub struct ConfigLayer {
     pub name: ConfigLayerName,
-    pub source: String,
     pub version: String,
     pub config: JsonValue,
 }
diff --git a/codex-rs/app-server/tests/suite/v2/config_rpc.rs b/codex-rs/app-server/tests/suite/v2/config_rpc.rs
index 199d2f88e6..d0cd78a99b 100644
--- a/codex-rs/app-server/tests/suite/v2/config_rpc.rs
+++ b/codex-rs/app-server/tests/suite/v2/config_rpc.rs
@@ -18,6 +18,7 @@ use codex_app_server_protocol::RequestId;
 use codex_app_server_protocol::SandboxMode;
 use codex_app_server_protocol::ToolsV2;
 use codex_app_server_protocol::WriteStatus;
+use codex_utils_absolute_path::AbsolutePathBuf;
 use pretty_assertions::assert_eq;
 use serde_json::json;
 use tempfile::TempDir;
@@ -42,6 +43,7 @@ model = "gpt-user"
 sandbox_mode = "workspace-write"
 "#,
     )?;
+    let user_file = AbsolutePathBuf::try_from(codex_home.path().join("config.toml"))?;
 
     let mut mcp = McpProcess::new(codex_home.path()).await?;
     timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
@@ -65,12 +67,19 @@ sandbox_mode = "workspace-write"
     assert_eq!(config.model.as_deref(), Some("gpt-user"));
     assert_eq!(
         origins.get("model").expect("origin").name,
-        ConfigLayerName::User
+        ConfigLayerName::User {
+            file: user_file.clone(),
+        }
     );
     let layers = layers.expect("layers present");
     assert_eq!(layers.len(), 2);
-    assert_eq!(layers[0].name, ConfigLayerName::SessionFlags);
-    assert_eq!(layers[1].name, ConfigLayerName::User);
+    assert_eq!(
+        layers[0].name,
+        ConfigLayerName::SessionFlags {
+            override_keys: Vec::new(),
+        }
+    );
+    assert_eq!(layers[1].name, ConfigLayerName::User { file: user_file });
 
     Ok(())
 }
@@ -88,6 +97,7 @@ web_search = true
 view_image = false
 "#,
     )?;
+    let user_file = AbsolutePathBuf::try_from(codex_home.path().join("config.toml"))?;
 
     let mut mcp = McpProcess::new(codex_home.path()).await?;
     timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
@@ -118,17 +128,26 @@ view_image = false
     );
     assert_eq!(
         origins.get("tools.web_search").expect("origin").name,
-        ConfigLayerName::User
+        ConfigLayerName::User {
+            file: user_file.clone(),
+        }
     );
     assert_eq!(
         origins.get("tools.view_image").expect("origin").name,
-        ConfigLayerName::User
+        ConfigLayerName::User {
+            file: user_file.clone(),
+        }
     );
 
     let layers = layers.expect("layers present");
     assert_eq!(layers.len(), 2);
-    assert_eq!(layers[0].name, ConfigLayerName::SessionFlags);
-    assert_eq!(layers[1].name, ConfigLayerName::User);
+    assert_eq!(
+        layers[0].name,
+        ConfigLayerName::SessionFlags {
+            override_keys: Vec::new(),
+        }
+    );
+    assert_eq!(layers[1].name, ConfigLayerName::User { file: user_file });
 
     Ok(())
 }
@@ -153,8 +172,10 @@ network_access = true
             serde_json::json!(user_dir)
         ),
     )?;
+    let user_file = AbsolutePathBuf::try_from(codex_home.path().join("config.toml"))?;
 
     let managed_path = codex_home.path().join("managed_config.toml");
+    let managed_file = AbsolutePathBuf::try_from(managed_path.clone())?;
     std::fs::write(
         &managed_path,
         format!(
@@ -197,19 +218,25 @@ writable_roots = [{}]
     assert_eq!(config.model.as_deref(), Some("gpt-system"));
     assert_eq!(
         origins.get("model").expect("origin").name,
-        ConfigLayerName::System
+        ConfigLayerName::System {
+            file: managed_file.clone(),
+        }
     );
 
     assert_eq!(config.approval_policy, Some(AskForApproval::Never));
     assert_eq!(
         origins.get("approval_policy").expect("origin").name,
-        ConfigLayerName::System
+        ConfigLayerName::System {
+            file: managed_file.clone(),
+        }
     );
 
     assert_eq!(config.sandbox_mode, Some(SandboxMode::WorkspaceWrite));
     assert_eq!(
         origins.get("sandbox_mode").expect("origin").name,
-        ConfigLayerName::User
+        ConfigLayerName::User {
+            file: user_file.clone(),
+        }
     );
 
     let sandbox = config
@@ -222,7 +249,9 @@ writable_roots = [{}]
             .get("sandbox_workspace_write.writable_roots.0")
             .expect("origin")
             .name,
-        ConfigLayerName::System
+        ConfigLayerName::System {
+            file: managed_file.clone(),
+        }
     );
 
     assert!(sandbox.network_access);
@@ -231,14 +260,24 @@ writable_roots = [{}]
             .get("sandbox_workspace_write.network_access")
             .expect("origin")
             .name,
-        ConfigLayerName::User
+        ConfigLayerName::User {
+            file: user_file.clone(),
+        }
     );
 
     let layers = layers.expect("layers present");
     assert_eq!(layers.len(), 3);
-    assert_eq!(layers[0].name, ConfigLayerName::System);
-    assert_eq!(layers[1].name, ConfigLayerName::SessionFlags);
-    assert_eq!(layers[2].name, ConfigLayerName::User);
+    assert_eq!(
+        layers[0].name,
+        ConfigLayerName::System { file: managed_file }
+    );
+    assert_eq!(
+        layers[1].name,
+        ConfigLayerName::SessionFlags {
+            override_keys: Vec::new(),
+        }
+    );
+    assert_eq!(layers[2].name, ConfigLayerName::User { file: user_file });
 
     Ok(())
 }
diff --git a/codex-rs/core/src/codex.rs b/codex-rs/core/src/codex.rs
index 9a21f7bfe2..5f0e322dae 100644
--- a/codex-rs/core/src/codex.rs
+++ b/codex-rs/core/src/codex.rs
@@ -2476,6 +2476,7 @@ async fn try_run_turn(
     let mut needs_follow_up = false;
     let mut last_agent_message: Option<String> = None;
     let mut active_item: Option<TurnItem> = None;
+    let mut should_emit_turn_diff = false;
     let receiving_span = info_span!("receiving_stream");
     let outcome: CodexResult<TurnRunResult> = loop {
         let handle_responses = info_span!(
@@ -2551,14 +2552,7 @@ async fn try_run_turn(
             } => {
                 sess.update_token_usage_info(&turn_context, token_usage.as_ref())
                     .await;
-                let unified_diff = {
-                    let mut tracker = turn_diff_tracker.lock().await;
-                    tracker.get_unified_diff()
-                };
-                if let Ok(Some(unified_diff)) = unified_diff {
-                    let msg = EventMsg::TurnDiff(TurnDiffEvent { unified_diff });
-                    sess.send_event(&turn_context, msg).await;
-                }
+                should_emit_turn_diff = true;
 
                 break Ok(TurnRunResult {
                     needs_follow_up,
@@ -2632,7 +2626,18 @@ async fn try_run_turn(
         }
     };
 
-    drain_in_flight(&mut in_flight, sess, turn_context).await?;
+    drain_in_flight(&mut in_flight, sess.clone(), turn_context.clone()).await?;
+
+    if should_emit_turn_diff {
+        let unified_diff = {
+            let mut tracker = turn_diff_tracker.lock().await;
+            tracker.get_unified_diff()
+        };
+        if let Ok(Some(unified_diff)) = unified_diff {
+            let msg = EventMsg::TurnDiff(TurnDiffEvent { unified_diff });
+            sess.clone().send_event(&turn_context, msg).await;
+        }
+    }
 
     outcome
 }
diff --git a/codex-rs/core/src/config/service.rs b/codex-rs/core/src/config/service.rs
index 393d637f31..ed561af61e 100644
--- a/codex-rs/core/src/config/service.rs
+++ b/codex-rs/core/src/config/service.rs
@@ -499,10 +499,10 @@ fn value_at_path<'a>(root: &'a TomlValue, segments: &[String]) -> Option<&'a Tom
 
 fn override_message(layer: &ConfigLayerName) -> String {
     match layer {
-        ConfigLayerName::Mdm => "Overridden by managed policy (mdm)".to_string(),
-        ConfigLayerName::System => "Overridden by managed config (system)".to_string(),
-        ConfigLayerName::SessionFlags => "Overridden by session flags".to_string(),
-        ConfigLayerName::User => "Overridden by user config".to_string(),
+        ConfigLayerName::Mdm { .. } => "Overridden by managed policy (mdm)".to_string(),
+        ConfigLayerName::System { .. } => "Overridden by managed config (system)".to_string(),
+        ConfigLayerName::SessionFlags { .. } => "Overridden by session flags".to_string(),
+        ConfigLayerName::User { .. } => "Overridden by user config".to_string(),
     }
 }
 
@@ -576,6 +576,7 @@ mod tests {
     use super::*;
     use anyhow::Result;
     use codex_app_server_protocol::AskForApproval;
+    use codex_utils_absolute_path::AbsolutePathBuf;
     use pretty_assertions::assert_eq;
     use tempfile::tempdir;
 
@@ -677,16 +678,19 @@ remote_compaction = true
     #[tokio::test]
     async fn read_includes_origins_and_layers() {
         let tmp = tempdir().expect("tempdir");
-        std::fs::write(tmp.path().join(CONFIG_TOML_FILE), "model = \"user\"").unwrap();
+        let user_path = tmp.path().join(CONFIG_TOML_FILE);
+        std::fs::write(&user_path, "model = \"user\"").unwrap();
+        let user_file = AbsolutePathBuf::try_from(user_path.clone()).expect("user file");
 
         let managed_path = tmp.path().join("managed_config.toml");
         std::fs::write(&managed_path, "approval_policy = \"never\"").unwrap();
+        let managed_file = AbsolutePathBuf::try_from(managed_path.clone()).expect("managed file");
 
         let service = ConfigService::with_overrides(
             tmp.path().to_path_buf(),
             vec![],
             LoaderOverrides {
-                managed_config_path: Some(managed_path),
+                managed_config_path: Some(managed_path.clone()),
                 #[cfg(target_os = "macos")]
                 managed_preferences_base64: None,
             },
@@ -707,12 +711,25 @@ remote_compaction = true
                 .get("approval_policy")
                 .expect("origin")
                 .name,
-            ConfigLayerName::System
+            ConfigLayerName::System {
+                file: managed_file.clone(),
+            }
         );
         let layers = response.layers.expect("layers present");
-        assert_eq!(layers.first().unwrap().name, ConfigLayerName::System);
-        assert_eq!(layers.get(1).unwrap().name, ConfigLayerName::SessionFlags);
-        assert_eq!(layers.last().unwrap().name, ConfigLayerName::User);
+        assert_eq!(
+            layers.first().unwrap().name,
+            ConfigLayerName::System { file: managed_file }
+        );
+        assert_eq!(
+            layers.get(1).unwrap().name,
+            ConfigLayerName::SessionFlags {
+                override_keys: Vec::new(),
+            }
+        );
+        assert_eq!(
+            layers.last().unwrap().name,
+            ConfigLayerName::User { file: user_file }
+        );
     }
 
     #[tokio::test]
@@ -726,12 +743,13 @@ remote_compaction = true
 
         let managed_path = tmp.path().join("managed_config.toml");
         std::fs::write(&managed_path, "approval_policy = \"never\"").unwrap();
+        let managed_file = AbsolutePathBuf::try_from(managed_path.clone()).expect("managed file");
 
         let service = ConfigService::with_overrides(
             tmp.path().to_path_buf(),
             vec![],
             LoaderOverrides {
-                managed_config_path: Some(managed_path),
+                managed_config_path: Some(managed_path.clone()),
                 #[cfg(target_os = "macos")]
                 managed_preferences_base64: None,
             },
@@ -764,7 +782,7 @@ remote_compaction = true
                 .get("approval_policy")
                 .expect("origin")
                 .name,
-            ConfigLayerName::System
+            ConfigLayerName::System { file: managed_file }
         );
         assert_eq!(result.status, WriteStatus::Ok);
         assert!(result.overridden_metadata.is_none());
@@ -773,7 +791,8 @@ remote_compaction = true
     #[tokio::test]
     async fn version_conflict_rejected() {
         let tmp = tempdir().expect("tempdir");
-        std::fs::write(tmp.path().join(CONFIG_TOML_FILE), "model = \"user\"").unwrap();
+        let user_path = tmp.path().join(CONFIG_TOML_FILE);
+        std::fs::write(&user_path, "model = \"user\"").unwrap();
 
         let service = ConfigService::new(tmp.path().to_path_buf(), vec![]);
         let error = service
@@ -830,7 +849,7 @@ remote_compaction = true
             tmp.path().to_path_buf(),
             vec![],
             LoaderOverrides {
-                managed_config_path: Some(managed_path),
+                managed_config_path: Some(managed_path.clone()),
                 #[cfg(target_os = "macos")]
                 managed_preferences_base64: None,
             },
@@ -860,10 +879,13 @@ remote_compaction = true
     #[tokio::test]
     async fn read_reports_managed_overrides_user_and_session_flags() {
         let tmp = tempdir().expect("tempdir");
-        std::fs::write(tmp.path().join(CONFIG_TOML_FILE), "model = \"user\"").unwrap();
+        let user_path = tmp.path().join(CONFIG_TOML_FILE);
+        std::fs::write(&user_path, "model = \"user\"").unwrap();
+        let user_file = AbsolutePathBuf::try_from(user_path.clone()).expect("user file");
 
         let managed_path = tmp.path().join("managed_config.toml");
         std::fs::write(&managed_path, "model = \"system\"").unwrap();
+        let managed_file = AbsolutePathBuf::try_from(managed_path.clone()).expect("managed file");
 
         let cli_overrides = vec![(
             "model".to_string(),
@@ -874,7 +896,7 @@ remote_compaction = true
             tmp.path().to_path_buf(),
             cli_overrides,
             LoaderOverrides {
-                managed_config_path: Some(managed_path),
+                managed_config_path: Some(managed_path.clone()),
                 #[cfg(target_os = "macos")]
                 managed_preferences_base64: None,
             },
@@ -890,12 +912,25 @@ remote_compaction = true
         assert_eq!(response.config.model.as_deref(), Some("system"));
         assert_eq!(
             response.origins.get("model").expect("origin").name,
-            ConfigLayerName::System
+            ConfigLayerName::System {
+                file: managed_file.clone(),
+            }
         );
         let layers = response.layers.expect("layers");
-        assert_eq!(layers.first().unwrap().name, ConfigLayerName::System);
-        assert_eq!(layers.get(1).unwrap().name, ConfigLayerName::SessionFlags);
-        assert_eq!(layers.get(2).unwrap().name, ConfigLayerName::User);
+        assert_eq!(
+            layers.first().unwrap().name,
+            ConfigLayerName::System { file: managed_file }
+        );
+        assert_eq!(
+            layers.get(1).unwrap().name,
+            ConfigLayerName::SessionFlags {
+                override_keys: vec!["model".to_string()],
+            }
+        );
+        assert_eq!(
+            layers.get(2).unwrap().name,
+            ConfigLayerName::User { file: user_file }
+        );
     }
 
     #[tokio::test]
@@ -905,12 +940,13 @@ remote_compaction = true
 
         let managed_path = tmp.path().join("managed_config.toml");
         std::fs::write(&managed_path, "approval_policy = \"never\"").unwrap();
+        let managed_file = AbsolutePathBuf::try_from(managed_path.clone()).expect("managed file");
 
         let service = ConfigService::with_overrides(
             tmp.path().to_path_buf(),
             vec![],
             LoaderOverrides {
-                managed_config_path: Some(managed_path),
+                managed_config_path: Some(managed_path.clone()),
                 #[cfg(target_os = "macos")]
                 managed_preferences_base64: None,
             },
@@ -929,7 +965,10 @@ remote_compaction = true
 
         assert_eq!(result.status, WriteStatus::OkOverridden);
         let overridden = result.overridden_metadata.expect("overridden metadata");
-        assert_eq!(overridden.overriding_layer.name, ConfigLayerName::System);
+        assert_eq!(
+            overridden.overriding_layer.name,
+            ConfigLayerName::System { file: managed_file }
+        );
         assert_eq!(overridden.effective_value, serde_json::json!("never"));
     }
 
diff --git a/codex-rs/core/src/config_loader/README.md b/codex-rs/core/src/config_loader/README.md
index da427c4544..9df656951c 100644
--- a/codex-rs/core/src/config_loader/README.md
+++ b/codex-rs/core/src/config_loader/README.md
@@ -16,7 +16,7 @@ Exported from `codex_core::config_loader`:
   - `origins() -> HashMap<String, ConfigLayerMetadata>`
   - `layers_high_to_low() -> Vec<ConfigLayer>`
   - `with_user_config(user_config) -> ConfigLayerStack`
-- `ConfigLayerEntry` (one layer’s `{name, source, config, version}`)
+- `ConfigLayerEntry` (one layer’s `{name, config, version}`; `name` carries source metadata)
 - `LoaderOverrides` (test/override hooks for managed config sources)
 - `merge_toml_values(base, overlay)` (public helper used elsewhere)
 
@@ -61,4 +61,3 @@ Implementation is split by concern:
 - `merge.rs`: recursive TOML merge.
 - `fingerprint.rs`: stable per-layer hashing and per-key origins traversal.
 - `macos.rs`: managed preferences integration (macOS only).
-
diff --git a/codex-rs/core/src/config_loader/mod.rs b/codex-rs/core/src/config_loader/mod.rs
index c7c522008d..89b225d6e6 100644
--- a/codex-rs/core/src/config_loader/mod.rs
+++ b/codex-rs/core/src/config_loader/mod.rs
@@ -10,9 +10,9 @@ mod tests;
 
 use crate::config::CONFIG_TOML_FILE;
 use codex_app_server_protocol::ConfigLayerName;
+use codex_utils_absolute_path::AbsolutePathBuf;
 use std::io;
 use std::path::Path;
-use std::path::PathBuf;
 use toml::Value as TomlValue;
 
 pub use merge::merge_toml_values;
@@ -20,8 +20,8 @@ pub use state::ConfigLayerEntry;
 pub use state::ConfigLayerStack;
 pub use state::LoaderOverrides;
 
-const SESSION_FLAGS_SOURCE: &str = "--config";
-const MDM_SOURCE: &str = "com.openai.codex/config_toml_base64";
+const MDM_PREFERENCES_DOMAIN: &str = "com.openai.codex";
+const MDM_PREFERENCES_KEY: &str = "config_toml_base64";
 
 /// Configuration layering pipeline (top overrides bottom):
 ///
@@ -51,24 +51,38 @@ pub async fn load_config_layers_state(
         .unwrap_or_else(|| layer_io::managed_config_default_path(codex_home));
 
     let layers = layer_io::load_config_layers_internal(codex_home, overrides).await?;
-    let cli_overrides = overrides::build_cli_overrides_layer(cli_overrides);
+    let session_override_keys = cli_overrides.iter().map(|(key, _)| key.clone()).collect();
+    let cli_overrides_layer = overrides::build_cli_overrides_layer(cli_overrides);
+    let user_file = AbsolutePathBuf::from_absolute_path(codex_home.join(CONFIG_TOML_FILE))?;
+
+    let system = match layers.managed_config {
+        Some(cfg) => {
+            let system_file = AbsolutePathBuf::from_absolute_path(managed_config_path.clone())?;
+            Some(ConfigLayerEntry::new(
+                ConfigLayerName::System { file: system_file },
+                cfg,
+            ))
+        }
+        None => None,
+    };
 
     Ok(ConfigLayerStack {
-        user: ConfigLayerEntry::new(
-            ConfigLayerName::User,
-            codex_home.join(CONFIG_TOML_FILE),
-            layers.base,
-        ),
+        user: ConfigLayerEntry::new(ConfigLayerName::User { file: user_file }, layers.base),
         session_flags: ConfigLayerEntry::new(
-            ConfigLayerName::SessionFlags,
-            PathBuf::from(SESSION_FLAGS_SOURCE),
-            cli_overrides,
+            ConfigLayerName::SessionFlags {
+                override_keys: session_override_keys,
+            },
+            cli_overrides_layer,
         ),
-        system: layers.managed_config.map(|cfg| {
-            ConfigLayerEntry::new(ConfigLayerName::System, managed_config_path.clone(), cfg)
+        system,
+        mdm: layers.managed_preferences.map(|cfg| {
+            ConfigLayerEntry::new(
+                ConfigLayerName::Mdm {
+                    domain: MDM_PREFERENCES_DOMAIN.to_string(),
+                    key: MDM_PREFERENCES_KEY.to_string(),
+                },
+                cfg,
+            )
         }),
-        mdm: layers
-            .managed_preferences
-            .map(|cfg| ConfigLayerEntry::new(ConfigLayerName::Mdm, PathBuf::from(MDM_SOURCE), cfg)),
     })
 }
diff --git a/codex-rs/core/src/config_loader/state.rs b/codex-rs/core/src/config_loader/state.rs
index e23cc243ce..b0c56af2e5 100644
--- a/codex-rs/core/src/config_loader/state.rs
+++ b/codex-rs/core/src/config_loader/state.rs
@@ -19,17 +19,15 @@ pub struct LoaderOverrides {
 #[derive(Debug, Clone)]
 pub struct ConfigLayerEntry {
     pub name: ConfigLayerName,
-    pub source: PathBuf,
     pub config: TomlValue,
     pub version: String,
 }
 
 impl ConfigLayerEntry {
-    pub fn new(name: ConfigLayerName, source: PathBuf, config: TomlValue) -> Self {
+    pub fn new(name: ConfigLayerName, config: TomlValue) -> Self {
         let version = version_for_toml(&config);
         Self {
             name,
-            source,
             config,
             version,
         }
@@ -38,7 +36,6 @@ impl ConfigLayerEntry {
     pub fn metadata(&self) -> ConfigLayerMetadata {
         ConfigLayerMetadata {
             name: self.name.clone(),
-            source: self.source.display().to_string(),
             version: self.version.clone(),
         }
     }
@@ -46,7 +43,6 @@ impl ConfigLayerEntry {
     pub fn as_layer(&self) -> ConfigLayer {
         ConfigLayer {
             name: self.name.clone(),
-            source: self.source.display().to_string(),
             version: self.version.clone(),
             config: serde_json::to_value(&self.config).unwrap_or(JsonValue::Null),
         }
@@ -64,11 +60,7 @@ pub struct ConfigLayerStack {
 impl ConfigLayerStack {
     pub fn with_user_config(&self, user_config: TomlValue) -> Self {
         Self {
-            user: ConfigLayerEntry::new(
-                self.user.name.clone(),
-                self.user.source.clone(),
-                user_config,
-            ),
+            user: ConfigLayerEntry::new(self.user.name.clone(), user_config),
             session_flags: self.session_flags.clone(),
             system: self.system.clone(),
             mdm: self.mdm.clone(),
diff --git a/codex-rs/core/src/openai_models/models_manager.rs b/codex-rs/core/src/openai_models/models_manager.rs
index b383079f44..844216e203 100644
--- a/codex-rs/core/src/openai_models/models_manager.rs
+++ b/codex-rs/core/src/openai_models/models_manager.rs
@@ -6,6 +6,7 @@ use codex_protocol::openai_models::ModelInfo;
 use codex_protocol::openai_models::ModelPreset;
 use codex_protocol::openai_models::ModelsResponse;
 use http::HeaderMap;
+use std::collections::HashSet;
 use std::path::PathBuf;
 use std::sync::Arc;
 use std::time::Duration;
@@ -35,7 +36,7 @@ const CODEX_AUTO_BALANCED_MODEL: &str = "codex-auto-balanced";
 #[derive(Debug)]
 pub struct ModelsManager {
     // todo(aibrahim) merge available_models and model family creation into one struct
-    available_models: RwLock<Vec<ModelPreset>>,
+    local_models: Vec<ModelPreset>,
     remote_models: RwLock<Vec<ModelInfo>>,
     auth_manager: Arc<AuthManager>,
     etag: RwLock<Option<String>>,
@@ -49,7 +50,7 @@ impl ModelsManager {
     pub fn new(auth_manager: Arc<AuthManager>) -> Self {
         let codex_home = auth_manager.codex_home().to_path_buf();
         Self {
-            available_models: RwLock::new(builtin_model_presets(auth_manager.get_auth_mode())),
+            local_models: builtin_model_presets(auth_manager.get_auth_mode()),
             remote_models: RwLock::new(Vec::new()),
             auth_manager,
             etag: RwLock::new(None),
@@ -64,7 +65,7 @@ impl ModelsManager {
     pub fn with_provider(auth_manager: Arc<AuthManager>, provider: ModelProviderInfo) -> Self {
         let codex_home = auth_manager.codex_home().to_path_buf();
         Self {
-            available_models: RwLock::new(builtin_model_presets(auth_manager.get_auth_mode())),
+            local_models: builtin_model_presets(auth_manager.get_auth_mode()),
             remote_models: RwLock::new(Vec::new()),
             auth_manager,
             etag: RwLock::new(None),
@@ -107,13 +108,13 @@ impl ModelsManager {
         if let Err(err) = self.refresh_available_models(config).await {
             error!("failed to refresh available models: {err}");
         }
-        self.available_models.read().await.clone()
+        let remote_models = self.remote_models.read().await.clone();
+        self.build_available_models(remote_models)
     }
 
     pub fn try_list_models(&self) -> Result<Vec<ModelPreset>, TryLockError> {
-        self.available_models
-            .try_read()
-            .map(|models| models.clone())
+        let remote_models = self.remote_models.try_read()?.clone();
+        Ok(self.build_available_models(remote_models))
     }
 
     fn find_family_for_model(slug: &str) -> ModelFamily {
@@ -123,8 +124,8 @@ impl ModelsManager {
     /// Look up the requested model family while applying remote metadata overrides.
     pub async fn construct_model_family(&self, model: &str, config: &Config) -> ModelFamily {
         Self::find_family_for_model(model)
-            .with_config_overrides(config)
             .with_remote_overrides(self.remote_models.read().await.clone())
+            .with_config_overrides(config)
     }
 
     pub async fn get_model(&self, model: &Option<String>, config: &Config) -> String {
@@ -136,11 +137,10 @@ impl ModelsManager {
         }
         // if codex-auto-balanced exists & signed in with chatgpt mode, return it, otherwise return the default model
         let auth_mode = self.auth_manager.get_auth_mode();
+        let remote_models = self.remote_models.read().await.clone();
         if auth_mode == Some(AuthMode::ChatGPT)
             && self
-                .available_models
-                .read()
-                .await
+                .build_available_models(remote_models)
                 .iter()
                 .any(|m| m.model == CODEX_AUTO_BALANCED_MODEL)
         {
@@ -163,7 +163,6 @@ impl ModelsManager {
     /// Replace the cached remote models and rebuild the derived presets list.
     async fn apply_remote_models(&self, models: Vec<ModelInfo>) {
         *self.remote_models.write().await = models;
-        self.build_available_models().await;
     }
 
     /// Attempt to satisfy the refresh from the cache when it matches the provider and TTL.
@@ -203,22 +202,55 @@ impl ModelsManager {
         }
     }
 
-    /// Convert remote model metadata into picker-ready presets, marking defaults.
-    async fn build_available_models(&self) {
-        let mut available_models = self.remote_models.read().await.clone();
-        available_models.sort_by(|a, b| a.priority.cmp(&b.priority));
-        let mut model_presets: Vec<ModelPreset> = available_models
-            .into_iter()
-            .map(Into::into)
-            .filter(|preset: &ModelPreset| preset.show_in_picker)
-            .collect();
-        if let Some(default) = model_presets.first_mut() {
+    /// Merge remote model metadata into picker-ready presets, preserving existing entries.
+    fn build_available_models(&self, mut remote_models: Vec<ModelInfo>) -> Vec<ModelPreset> {
+        remote_models.sort_by(|a, b| a.priority.cmp(&b.priority));
+
+        let remote_presets: Vec<ModelPreset> = remote_models.into_iter().map(Into::into).collect();
+        let existing_presets = self.local_models.clone();
+        let mut merged_presets = Self::merge_presets(remote_presets, existing_presets);
+        merged_presets = Self::filter_visible_models(merged_presets);
+
+        let has_default = merged_presets.iter().any(|preset| preset.is_default);
+        if let Some(default) = merged_presets.first_mut()
+            && !has_default
+        {
             default.is_default = true;
         }
-        {
-            let mut available_models_guard = self.available_models.write().await;
-            *available_models_guard = model_presets;
+
+        merged_presets
+    }
+
+    fn filter_visible_models(models: Vec<ModelPreset>) -> Vec<ModelPreset> {
+        models
+            .into_iter()
+            .filter(|model| model.show_in_picker)
+            .collect()
+    }
+
+    fn merge_presets(
+        remote_presets: Vec<ModelPreset>,
+        existing_presets: Vec<ModelPreset>,
+    ) -> Vec<ModelPreset> {
+        if remote_presets.is_empty() {
+            return existing_presets;
         }
+
+        let remote_slugs: HashSet<&str> = remote_presets
+            .iter()
+            .map(|preset| preset.model.as_str())
+            .collect();
+
+        let mut merged_presets = remote_presets.clone();
+        for mut preset in existing_presets {
+            if remote_slugs.contains(preset.model.as_str()) {
+                continue;
+            }
+            preset.is_default = false;
+            merged_presets.push(preset);
+        }
+
+        merged_presets
     }
 
     fn cache_path(&self) -> PathBuf {
@@ -261,11 +293,21 @@ mod tests {
     use crate::model_provider_info::WireApi;
     use codex_protocol::openai_models::ModelsResponse;
     use core_test_support::responses::mount_models_once;
+    use pretty_assertions::assert_eq;
     use serde_json::json;
     use tempfile::tempdir;
     use wiremock::MockServer;
 
     fn remote_model(slug: &str, display: &str, priority: i32) -> ModelInfo {
+        remote_model_with_visibility(slug, display, priority, "list")
+    }
+
+    fn remote_model_with_visibility(
+        slug: &str,
+        display: &str,
+        priority: i32,
+        visibility: &str,
+    ) -> ModelInfo {
         serde_json::from_value(json!({
             "slug": slug,
             "display_name": display,
@@ -273,7 +315,7 @@ mod tests {
             "default_reasoning_level": "medium",
             "supported_reasoning_levels": [{"effort": "low", "description": "low"}, {"effort": "medium", "description": "medium"}],
             "shell_type": "shell_command",
-            "visibility": "list",
+            "visibility": visibility,
             "minimal_client_version": [0, 1, 0],
             "supported_in_api": true,
             "priority": priority,
@@ -347,14 +389,23 @@ mod tests {
         assert_eq!(cached_remote, remote_models);
 
         let available = manager.list_models(&config).await;
-        assert_eq!(available.len(), 2);
-        assert_eq!(available[0].model, "priority-high");
+        let high_idx = available
+            .iter()
+            .position(|model| model.model == "priority-high")
+            .expect("priority-high should be listed");
+        let low_idx = available
+            .iter()
+            .position(|model| model.model == "priority-low")
+            .expect("priority-low should be listed");
         assert!(
-            available[0].is_default,
+            high_idx < low_idx,
+            "higher priority should be listed before lower priority"
+        );
+        assert!(
+            available[high_idx].is_default,
             "highest priority should be default"
         );
-        assert_eq!(available[1].model, "priority-low");
-        assert!(!available[1].is_default);
+        assert!(!available[low_idx].is_default);
         assert_eq!(
             models_mock.requests().len(),
             1,
@@ -493,4 +544,94 @@ mod tests {
             "stale cache refresh should fetch /models once"
         );
     }
+
+    #[tokio::test]
+    async fn refresh_available_models_drops_removed_remote_models() {
+        let server = MockServer::start().await;
+        let initial_models = vec![remote_model("remote-old", "Remote Old", 1)];
+        let initial_mock = mount_models_once(
+            &server,
+            ModelsResponse {
+                models: initial_models,
+                etag: String::new(),
+            },
+        )
+        .await;
+
+        let codex_home = tempdir().expect("temp dir");
+        let mut config = Config::load_from_base_config_with_overrides(
+            ConfigToml::default(),
+            ConfigOverrides::default(),
+            codex_home.path().to_path_buf(),
+        )
+        .expect("load default test config");
+        config.features.enable(Feature::RemoteModels);
+        let auth_manager =
+            AuthManager::from_auth_for_testing(CodexAuth::from_api_key("Test API Key"));
+        let provider = provider_for(server.uri());
+        let mut manager = ModelsManager::with_provider(auth_manager, provider);
+        manager.cache_ttl = Duration::ZERO;
+
+        manager
+            .refresh_available_models(&config)
+            .await
+            .expect("initial refresh succeeds");
+
+        server.reset().await;
+        let refreshed_models = vec![remote_model("remote-new", "Remote New", 1)];
+        let refreshed_mock = mount_models_once(
+            &server,
+            ModelsResponse {
+                models: refreshed_models,
+                etag: String::new(),
+            },
+        )
+        .await;
+
+        manager
+            .refresh_available_models(&config)
+            .await
+            .expect("second refresh succeeds");
+
+        let available = manager
+            .try_list_models()
+            .expect("models should be available");
+        assert!(
+            available.iter().any(|preset| preset.model == "remote-new"),
+            "new remote model should be listed"
+        );
+        assert!(
+            !available.iter().any(|preset| preset.model == "remote-old"),
+            "removed remote model should not be listed"
+        );
+        assert_eq!(
+            initial_mock.requests().len(),
+            1,
+            "initial refresh should only hit /models once"
+        );
+        assert_eq!(
+            refreshed_mock.requests().len(),
+            1,
+            "second refresh should only hit /models once"
+        );
+    }
+
+    #[test]
+    fn build_available_models_picks_default_after_hiding_hidden_models() {
+        let auth_manager =
+            AuthManager::from_auth_for_testing(CodexAuth::from_api_key("Test API Key"));
+        let provider = provider_for("http://example.test".to_string());
+        let mut manager = ModelsManager::with_provider(auth_manager, provider);
+        manager.local_models = Vec::new();
+
+        let hidden_model = remote_model_with_visibility("hidden", "Hidden", 0, "hide");
+        let visible_model = remote_model_with_visibility("visible", "Visible", 1, "list");
+
+        let mut expected = ModelPreset::from(visible_model.clone());
+        expected.is_default = true;
+
+        let available = manager.build_available_models(vec![hidden_model, visible_model]);
+
+        assert_eq!(available, vec![expected]);
+    }
 }
diff --git a/codex-rs/core/src/stream_events_utils.rs b/codex-rs/core/src/stream_events_utils.rs
index e1c9a65252..1373fdf248 100644
--- a/codex-rs/core/src/stream_events_utils.rs
+++ b/codex-rs/core/src/stream_events_utils.rs
@@ -16,7 +16,6 @@ use codex_protocol::models::FunctionCallOutputPayload;
 use codex_protocol::models::ResponseInputItem;
 use codex_protocol::models::ResponseItem;
 use futures::Future;
-use tracing::Instrument;
 use tracing::debug;
 use tracing::instrument;
 
@@ -59,16 +58,10 @@ pub(crate) async fn handle_output_item_done(
                 .await;
 
             let cancellation_token = ctx.cancellation_token.child_token();
-            let tool_runtime = ctx.tool_runtime.clone();
-
             let tool_future: InFlightFuture<'static> = Box::pin(
-                async move {
-                    let response_input = tool_runtime
-                        .handle_tool_call(call, cancellation_token)
-                        .await?;
-                    Ok(response_input)
-                }
-                .in_current_span(),
+                ctx.tool_runtime
+                    .clone()
+                    .handle_tool_call(call, cancellation_token),
             );
 
             output.needs_follow_up = true;
diff --git a/codex-rs/core/src/tools/mod.rs b/codex-rs/core/src/tools/mod.rs
index c1ef916d7a..9536eedafe 100644
--- a/codex-rs/core/src/tools/mod.rs
+++ b/codex-rs/core/src/tools/mod.rs
@@ -70,9 +70,11 @@ pub fn format_exec_output_for_model_freeform(
     // round to 1 decimal place
     let duration_seconds = ((exec_output.duration.as_secs_f32()) * 10.0).round() / 10.0;
 
-    let total_lines = exec_output.aggregated_output.text.lines().count();
+    let content = build_content_with_timeout(exec_output);
 
-    let formatted_output = truncate_text(&exec_output.aggregated_output.text, truncation_policy);
+    let total_lines = content.lines().count();
+
+    let formatted_output = truncate_text(&content, truncation_policy);
 
     let mut sections = Vec::new();
 
@@ -92,21 +94,21 @@ pub fn format_exec_output_str(
     exec_output: &ExecToolCallOutput,
     truncation_policy: TruncationPolicy,
 ) -> String {
-    let ExecToolCallOutput {
-        aggregated_output, ..
-    } = exec_output;
-
-    let content = aggregated_output.text.as_str();
-
-    let body = if exec_output.timed_out {
-        format!(
-            "command timed out after {} milliseconds\n{content}",
-            exec_output.duration.as_millis()
-        )
-    } else {
-        content.to_string()
-    };
+    let content = build_content_with_timeout(exec_output);
 
     // Truncate for model consumption before serialization.
-    formatted_truncate_text(&body, truncation_policy)
+    formatted_truncate_text(&content, truncation_policy)
+}
+
+/// Extracts exec output content and prepends a timeout message if the command timed out.
+fn build_content_with_timeout(exec_output: &ExecToolCallOutput) -> String {
+    if exec_output.timed_out {
+        format!(
+            "command timed out after {} milliseconds\n{}",
+            exec_output.duration.as_millis(),
+            exec_output.aggregated_output.text
+        )
+    } else {
+        exec_output.aggregated_output.text.clone()
+    }
 }
diff --git a/codex-rs/core/src/tools/parallel.rs b/codex-rs/core/src/tools/parallel.rs
index feef518e57..d146507e5c 100644
--- a/codex-rs/core/src/tools/parallel.rs
+++ b/codex-rs/core/src/tools/parallel.rs
@@ -47,7 +47,7 @@ impl ToolCallRuntime {
 
     #[instrument(skip_all, fields(call = ?call))]
     pub(crate) fn handle_tool_call(
-        &self,
+        self,
         call: ToolCall,
         cancellation_token: CancellationToken,
     ) -> impl std::future::Future<Output = Result<ResponseInputItem, CodexErr>> {
diff --git a/codex-rs/core/tests/common/Cargo.toml b/codex-rs/core/tests/common/Cargo.toml
index 95ea788b4c..0f0abbb3cb 100644
--- a/codex-rs/core/tests/common/Cargo.toml
+++ b/codex-rs/core/tests/common/Cargo.toml
@@ -22,3 +22,7 @@ tokio = { workspace = true, features = ["time"] }
 walkdir = { workspace = true }
 wiremock = { workspace = true }
 shlex = { workspace = true }
+
+[dev-dependencies]
+pretty_assertions = { workspace = true }
+reqwest = { workspace = true }
diff --git a/codex-rs/core/tests/common/lib.rs b/codex-rs/core/tests/common/lib.rs
index 61bac30cb1..dc0cc53f46 100644
--- a/codex-rs/core/tests/common/lib.rs
+++ b/codex-rs/core/tests/common/lib.rs
@@ -14,6 +14,7 @@ use std::path::PathBuf;
 use assert_cmd::cargo::cargo_bin;
 
 pub mod responses;
+pub mod streaming_sse;
 pub mod test_codex;
 pub mod test_codex_exec;
 
diff --git a/codex-rs/core/tests/common/streaming_sse.rs b/codex-rs/core/tests/common/streaming_sse.rs
new file mode 100644
index 0000000000..4f1b3673b0
--- /dev/null
+++ b/codex-rs/core/tests/common/streaming_sse.rs
@@ -0,0 +1,680 @@
+use std::collections::VecDeque;
+use std::sync::Arc;
+use std::time::SystemTime;
+use std::time::UNIX_EPOCH;
+
+use tokio::io::AsyncReadExt;
+use tokio::io::AsyncWriteExt;
+use tokio::net::TcpListener;
+use tokio::sync::Mutex as TokioMutex;
+use tokio::sync::oneshot;
+
+/// Streaming SSE chunk payload gated by a per-chunk signal.
+#[derive(Debug)]
+pub struct StreamingSseChunk {
+    pub gate: Option<oneshot::Receiver<()>>,
+    pub body: String,
+}
+
+/// Minimal streaming SSE server for tests that need gated per-chunk delivery.
+pub struct StreamingSseServer {
+    uri: String,
+    shutdown: oneshot::Sender<()>,
+    task: tokio::task::JoinHandle<()>,
+}
+
+impl StreamingSseServer {
+    pub fn uri(&self) -> &str {
+        &self.uri
+    }
+
+    pub async fn shutdown(self) {
+        let _ = self.shutdown.send(());
+        let _ = self.task.await;
+    }
+}
+
+/// Starts a lightweight HTTP server that supports:
+/// - GET /v1/models -> empty models response
+/// - POST /v1/responses -> SSE stream gated per-chunk, served in order
+///
+/// Returns the server handle and a list of receivers that fire when each
+/// response stream finishes sending its final chunk.
+pub async fn start_streaming_sse_server(
+    responses: Vec<Vec<StreamingSseChunk>>,
+) -> (StreamingSseServer, Vec<oneshot::Receiver<i64>>) {
+    let listener = TcpListener::bind("127.0.0.1:0")
+        .await
+        .expect("bind streaming SSE server");
+    let addr = listener.local_addr().expect("streaming SSE server address");
+    let uri = format!("http://{addr}");
+
+    let mut completion_senders = Vec::with_capacity(responses.len());
+    let mut completion_receivers = Vec::with_capacity(responses.len());
+    for _ in 0..responses.len() {
+        let (tx, rx) = oneshot::channel();
+        completion_senders.push(tx);
+        completion_receivers.push(rx);
+    }
+
+    let state = Arc::new(TokioMutex::new(StreamingSseState {
+        responses: VecDeque::from(responses),
+        completions: VecDeque::from(completion_senders),
+    }));
+    let (shutdown_tx, mut shutdown_rx) = oneshot::channel();
+
+    let task = tokio::spawn(async move {
+        loop {
+            tokio::select! {
+                _ = &mut shutdown_rx => break,
+                accept_res = listener.accept() => {
+                    let (mut stream, _) = accept_res.expect("accept streaming SSE connection");
+                    let state = Arc::clone(&state);
+                    tokio::spawn(async move {
+                        let (request, body_prefix) = read_http_request(&mut stream).await;
+                        let Some((method, path)) = parse_request_line(&request) else {
+                            let _ = write_http_response(&mut stream, 400, "bad request", "text/plain").await;
+                            return;
+                        };
+
+                        if method == "GET" && path == "/v1/models" {
+                            if drain_request_body(&mut stream, &request, body_prefix)
+                                .await
+                                .is_err()
+                            {
+                                let _ = write_http_response(&mut stream, 400, "bad request", "text/plain").await;
+                                return;
+                            }
+                            let body = serde_json::json!({
+                                "data": [],
+                                "object": "list"
+                            })
+                            .to_string();
+                            let _ = write_http_response(&mut stream, 200, &body, "application/json").await;
+                            return;
+                        }
+
+                        if method == "POST" && path == "/v1/responses" {
+                            if drain_request_body(&mut stream, &request, body_prefix)
+                                .await
+                                .is_err()
+                            {
+                                let _ = write_http_response(&mut stream, 400, "bad request", "text/plain").await;
+                                return;
+                            }
+                            let Some((chunks, completion)) = take_next_stream(&state).await else {
+                                let _ = write_http_response(&mut stream, 500, "no responses queued", "text/plain").await;
+                                return;
+                            };
+
+                            if write_sse_headers(&mut stream).await.is_err() {
+                                return;
+                            }
+
+                            for chunk in chunks {
+                                if let Some(gate) = chunk.gate
+                                    && gate.await.is_err() {
+                                        return;
+                                    }
+                                if stream.write_all(chunk.body.as_bytes()).await.is_err() {
+                                    return;
+                                }
+                                let _ = stream.flush().await;
+                            }
+
+                            let _ = completion.send(unix_ms_now());
+                            let _ = stream.shutdown().await;
+                            return;
+                        }
+
+                        let _ = write_http_response(&mut stream, 404, "not found", "text/plain").await;
+                    });
+                }
+            }
+        }
+    });
+
+    (
+        StreamingSseServer {
+            uri,
+            shutdown: shutdown_tx,
+            task,
+        },
+        completion_receivers,
+    )
+}
+
+struct StreamingSseState {
+    responses: VecDeque<Vec<StreamingSseChunk>>,
+    completions: VecDeque<oneshot::Sender<i64>>,
+}
+
+async fn take_next_stream(
+    state: &TokioMutex<StreamingSseState>,
+) -> Option<(Vec<StreamingSseChunk>, oneshot::Sender<i64>)> {
+    let mut guard = state.lock().await;
+    let chunks = guard.responses.pop_front()?;
+    let completion = guard.completions.pop_front()?;
+    Some((chunks, completion))
+}
+
+async fn read_http_request(stream: &mut tokio::net::TcpStream) -> (String, Vec<u8>) {
+    let mut buf = Vec::new();
+    let mut scratch = [0u8; 1024];
+    loop {
+        let read = stream.read(&mut scratch).await.unwrap_or(0);
+        if read == 0 {
+            break;
+        }
+        buf.extend_from_slice(&scratch[..read]);
+        if let Some(end) = header_terminator_index(&buf) {
+            let header_end = end + 4;
+            let header = String::from_utf8_lossy(&buf[..header_end]).into_owned();
+            let rest = buf[header_end..].to_vec();
+            return (header, rest);
+        }
+    }
+    (String::from_utf8_lossy(&buf).into_owned(), Vec::new())
+}
+
+fn parse_request_line(request: &str) -> Option<(&str, &str)> {
+    let line = request.lines().next()?;
+    let mut parts = line.split_whitespace();
+    let method = parts.next()?;
+    let path = parts.next()?;
+    Some((method, path))
+}
+
+fn header_terminator_index(buf: &[u8]) -> Option<usize> {
+    buf.windows(4).position(|w| w == b"\r\n\r\n")
+}
+
+fn content_length(headers: &str) -> Option<usize> {
+    headers.lines().skip(1).find_map(|line| {
+        let mut parts = line.splitn(2, ':');
+        let name = parts.next()?.trim();
+        let value = parts.next()?.trim();
+        if name.eq_ignore_ascii_case("content-length") {
+            value.parse::<usize>().ok()
+        } else {
+            None
+        }
+    })
+}
+
+async fn drain_request_body(
+    stream: &mut tokio::net::TcpStream,
+    headers: &str,
+    mut body_prefix: Vec<u8>,
+) -> std::io::Result<()> {
+    let Some(content_len) = content_length(headers) else {
+        return Ok(());
+    };
+
+    if body_prefix.len() > content_len {
+        body_prefix.truncate(content_len);
+    }
+
+    let remaining = content_len.saturating_sub(body_prefix.len());
+    if remaining == 0 {
+        return Ok(());
+    }
+
+    let mut rest = vec![0u8; remaining];
+    stream.read_exact(&mut rest).await?;
+    Ok(())
+}
+
+async fn write_sse_headers(stream: &mut tokio::net::TcpStream) -> std::io::Result<()> {
+    let headers = "HTTP/1.1 200 OK\r\ncontent-type: text/event-stream\r\ncache-control: no-cache\r\nconnection: close\r\n\r\n";
+    stream.write_all(headers.as_bytes()).await
+}
+
+async fn write_http_response(
+    stream: &mut tokio::net::TcpStream,
+    status: i64,
+    body: &str,
+    content_type: &str,
+) -> std::io::Result<()> {
+    let body_len = body.len();
+    let headers = format!(
+        "HTTP/1.1 {status} OK\r\ncontent-type: {content_type}\r\ncontent-length: {body_len}\r\nconnection: close\r\n\r\n"
+    );
+    stream.write_all(headers.as_bytes()).await?;
+    stream.write_all(body.as_bytes()).await?;
+    stream.shutdown().await
+}
+
+fn unix_ms_now() -> i64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_millis() as i64
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pretty_assertions::assert_eq;
+    use reqwest::StatusCode;
+    use tokio::net::TcpStream;
+    use tokio::time::Duration;
+    use tokio::time::timeout;
+
+    fn split_response(response: &str) -> (&str, &str) {
+        response
+            .split_once("\r\n\r\n")
+            .expect("response missing header separator")
+    }
+
+    fn status_code(headers: &str) -> u16 {
+        let line = headers.lines().next().expect("status line");
+        let mut parts = line.split_whitespace();
+        let _ = parts.next();
+        let status = parts.next().expect("status code");
+        status.parse().expect("parse status code")
+    }
+
+    fn header_value<'a>(headers: &'a str, name: &str) -> Option<&'a str> {
+        headers.lines().skip(1).find_map(|line| {
+            let mut parts = line.splitn(2, ':');
+            let key = parts.next()?.trim();
+            let value = parts.next()?.trim();
+            if key.eq_ignore_ascii_case(name) {
+                Some(value)
+            } else {
+                None
+            }
+        })
+    }
+
+    async fn connect(uri: &str) -> TcpStream {
+        let addr = uri.strip_prefix("http://").expect("uri should be http");
+        TcpStream::connect(addr)
+            .await
+            .expect("connect to streaming SSE server")
+    }
+
+    async fn read_to_end(stream: &mut TcpStream) -> String {
+        let mut buf = Vec::new();
+        stream.read_to_end(&mut buf).await.expect("read response");
+        String::from_utf8_lossy(&buf).into_owned()
+    }
+
+    async fn read_until(stream: &mut TcpStream, needle: &str) -> (String, String) {
+        let mut buf = Vec::new();
+        let mut scratch = [0u8; 256];
+        let needle_bytes = needle.as_bytes();
+        loop {
+            let read = stream.read(&mut scratch).await.expect("read response");
+            if read == 0 {
+                break;
+            }
+            buf.extend_from_slice(&scratch[..read]);
+            if let Some(pos) = buf
+                .windows(needle_bytes.len())
+                .position(|window| window == needle_bytes)
+            {
+                let end = pos + needle_bytes.len();
+                let headers = String::from_utf8_lossy(&buf[..end]).into_owned();
+                let remainder = String::from_utf8_lossy(&buf[end..]).into_owned();
+                return (headers, remainder);
+            }
+        }
+        (String::from_utf8_lossy(&buf).into_owned(), String::new())
+    }
+
+    async fn send_request(stream: &mut TcpStream, request: &str) {
+        stream
+            .write_all(request.as_bytes())
+            .await
+            .expect("write request");
+    }
+
+    #[tokio::test]
+    async fn get_models_returns_empty_list() {
+        let (server, _) = start_streaming_sse_server(Vec::new()).await;
+        let mut stream = connect(server.uri()).await;
+        send_request(
+            &mut stream,
+            "GET /v1/models HTTP/1.1\r\nHost: 127.0.0.1\r\n\r\n",
+        )
+        .await;
+        let response = read_to_end(&mut stream).await;
+        let (headers, body) = split_response(&response);
+        assert_eq!(status_code(headers), 200);
+        assert_eq!(
+            header_value(headers, "content-type"),
+            Some("application/json")
+        );
+        let parsed: serde_json::Value = serde_json::from_str(body).expect("parse json body");
+        assert_eq!(
+            parsed,
+            serde_json::json!({
+                "data": [],
+                "object": "list"
+            })
+        );
+        server.shutdown().await;
+    }
+
+    #[tokio::test]
+    async fn post_responses_streams_in_order_and_closes() {
+        let chunks = vec![
+            StreamingSseChunk {
+                gate: None,
+                body: "event: one\n\n".to_string(),
+            },
+            StreamingSseChunk {
+                gate: None,
+                body: "event: two\n\n".to_string(),
+            },
+        ];
+        let (server, mut completions) = start_streaming_sse_server(vec![chunks]).await;
+        let mut stream = connect(server.uri()).await;
+        send_request(
+            &mut stream,
+            "POST /v1/responses HTTP/1.1\r\nHost: 127.0.0.1\r\nContent-Length: 0\r\n\r\n",
+        )
+        .await;
+        let response = read_to_end(&mut stream).await;
+        let (headers, body) = split_response(&response);
+        assert_eq!(status_code(headers), 200);
+        assert_eq!(
+            header_value(headers, "content-type"),
+            Some("text/event-stream")
+        );
+        assert_eq!(body, "event: one\n\nevent: two\n\n");
+        let mut extra = [0u8; 1];
+        let read = stream.read(&mut extra).await.expect("read after eof");
+        assert_eq!(read, 0);
+        let completion = completions.pop().expect("completion receiver");
+        let timestamp = completion.await.expect("completion timestamp");
+        assert!(timestamp > 0);
+        server.shutdown().await;
+    }
+
+    #[tokio::test]
+    async fn none_gate_streams_immediately() {
+        let chunks = vec![StreamingSseChunk {
+            gate: None,
+            body: "event: immediate\n\n".to_string(),
+        }];
+        let (server, _) = start_streaming_sse_server(vec![chunks]).await;
+        let mut stream = connect(server.uri()).await;
+        send_request(
+            &mut stream,
+            "POST /v1/responses HTTP/1.1\r\nHost: 127.0.0.1\r\nContent-Length: 0\r\n\r\n",
+        )
+        .await;
+        let (headers, remainder) = read_until(&mut stream, "\r\n\r\n").await;
+        let (headers, _) = split_response(&headers);
+        assert_eq!(status_code(headers), 200);
+        let immediate = format!("{remainder}{}", read_to_end(&mut stream).await);
+        assert_eq!(immediate, "event: immediate\n\n");
+        server.shutdown().await;
+    }
+
+    #[tokio::test]
+    async fn post_responses_with_no_queue_returns_500() {
+        let (server, _) = start_streaming_sse_server(Vec::new()).await;
+        let mut stream = connect(server.uri()).await;
+        send_request(
+            &mut stream,
+            "POST /v1/responses HTTP/1.1\r\nHost: 127.0.0.1\r\nContent-Length: 0\r\n\r\n",
+        )
+        .await;
+        let response = read_to_end(&mut stream).await;
+        let (headers, body) = split_response(&response);
+        assert_eq!(status_code(headers), 500);
+        assert_eq!(header_value(headers, "content-type"), Some("text/plain"));
+        assert_eq!(body, "no responses queued");
+        server.shutdown().await;
+    }
+
+    #[tokio::test]
+    async fn gated_chunks_wait_for_signal_and_preserve_order() {
+        let (gate_one_tx, gate_one_rx) = oneshot::channel();
+        let (gate_two_tx, gate_two_rx) = oneshot::channel();
+        let chunks = vec![
+            StreamingSseChunk {
+                gate: Some(gate_one_rx),
+                body: "event: one\n\n".to_string(),
+            },
+            StreamingSseChunk {
+                gate: Some(gate_two_rx),
+                body: "event: two\n\n".to_string(),
+            },
+        ];
+        let (server, _) = start_streaming_sse_server(vec![chunks]).await;
+        let mut stream = connect(server.uri()).await;
+        send_request(
+            &mut stream,
+            "POST /v1/responses HTTP/1.1\r\nHost: 127.0.0.1\r\nContent-Length: 0\r\n\r\n",
+        )
+        .await;
+        let (headers, remainder) = read_until(&mut stream, "\r\n\r\n").await;
+        let (headers, _) = split_response(&headers);
+        assert_eq!(status_code(headers), 200);
+        assert_eq!(
+            header_value(headers, "content-type"),
+            Some("text/event-stream")
+        );
+        assert!(
+            remainder.is_empty(),
+            "unexpected body before gate: {remainder:?}"
+        );
+        let mut scratch = [0u8; 32];
+        let pending = timeout(Duration::from_millis(200), stream.read(&mut scratch)).await;
+        assert!(pending.is_err());
+
+        let _ = gate_one_tx.send(());
+        let mut first_chunk = vec![0u8; "event: one\n\n".len()];
+        stream
+            .read_exact(&mut first_chunk)
+            .await
+            .expect("read first chunk");
+        assert_eq!(String::from_utf8_lossy(&first_chunk), "event: one\n\n");
+        let pending = timeout(Duration::from_millis(200), stream.read(&mut scratch)).await;
+        assert!(pending.is_err());
+
+        let _ = gate_two_tx.send(());
+        let remaining = read_to_end(&mut stream).await;
+        assert_eq!(remaining, "event: two\n\n");
+        server.shutdown().await;
+    }
+
+    #[tokio::test]
+    async fn multiple_responses_are_fifo_and_completion_timestamps_monotonic() {
+        let first_chunks = vec![StreamingSseChunk {
+            gate: None,
+            body: "event: first\n\n".to_string(),
+        }];
+        let second_chunks = vec![StreamingSseChunk {
+            gate: None,
+            body: "event: second\n\n".to_string(),
+        }];
+        let (server, mut completions) =
+            start_streaming_sse_server(vec![first_chunks, second_chunks]).await;
+
+        let mut first_stream = connect(server.uri()).await;
+        send_request(
+            &mut first_stream,
+            "POST /v1/responses HTTP/1.1\r\nHost: 127.0.0.1\r\nContent-Length: 0\r\n\r\n",
+        )
+        .await;
+        let first_response = read_to_end(&mut first_stream).await;
+        let (_, first_body) = split_response(&first_response);
+        assert_eq!(first_body, "event: first\n\n");
+
+        let mut second_stream = connect(server.uri()).await;
+        send_request(
+            &mut second_stream,
+            "POST /v1/responses HTTP/1.1\r\nHost: 127.0.0.1\r\nContent-Length: 0\r\n\r\n",
+        )
+        .await;
+        let second_response = read_to_end(&mut second_stream).await;
+        let (_, second_body) = split_response(&second_response);
+        assert_eq!(second_body, "event: second\n\n");
+
+        let first_completion = completions.remove(0);
+        let second_completion = completions.remove(0);
+        let first_timestamp = first_completion.await.expect("first completion");
+        let second_timestamp = second_completion.await.expect("second completion");
+        assert!(first_timestamp > 0);
+        assert!(second_timestamp > 0);
+        assert!(first_timestamp <= second_timestamp);
+        assert!(completions.is_empty());
+        server.shutdown().await;
+    }
+
+    #[tokio::test]
+    async fn unknown_route_returns_404() {
+        let (server, _) = start_streaming_sse_server(Vec::new()).await;
+        let mut stream = connect(server.uri()).await;
+        send_request(
+            &mut stream,
+            "GET /v1/unknown HTTP/1.1\r\nHost: 127.0.0.1\r\n\r\n",
+        )
+        .await;
+        let response = read_to_end(&mut stream).await;
+        let (headers, body) = split_response(&response);
+        assert_eq!(status_code(headers), 404);
+        assert_eq!(header_value(headers, "content-type"), Some("text/plain"));
+        assert_eq!(body, "not found");
+        server.shutdown().await;
+    }
+
+    #[tokio::test]
+    async fn malformed_request_returns_400() {
+        let (server, _) = start_streaming_sse_server(Vec::new()).await;
+        let mut stream = connect(server.uri()).await;
+        send_request(&mut stream, "BAD\r\n\r\n").await;
+        let response = read_to_end(&mut stream).await;
+        let (headers, body) = split_response(&response);
+        assert_eq!(status_code(headers), 400);
+        assert_eq!(header_value(headers, "content-type"), Some("text/plain"));
+        assert_eq!(body, "bad request");
+        server.shutdown().await;
+    }
+
+    #[tokio::test]
+    async fn responses_post_drains_request_body() {
+        let response_body = r#"event: response.completed
+data: {"type":"response.completed","response":{"id":"resp-1"}}
+
+"#;
+        let (server, mut completions) = start_streaming_sse_server(vec![vec![StreamingSseChunk {
+            gate: None,
+            body: response_body.to_string(),
+        }]])
+        .await;
+
+        let url = format!("{}/v1/responses", server.uri());
+        let payload = serde_json::json!({
+            "model": "gpt-5.1",
+            "instructions": "test",
+            "input": [{"type": "message", "role": "user", "content": [{"type": "input_text", "text": "hello"}]}],
+            "stream": true
+        });
+
+        let resp = reqwest::Client::new()
+            .post(url)
+            .json(&payload)
+            .send()
+            .await
+            .expect("send request");
+        assert_eq!(resp.status(), StatusCode::OK);
+
+        let bytes = resp.bytes().await.expect("read response body");
+        assert_eq!(bytes, response_body.as_bytes());
+
+        let completion = completions.remove(0);
+        let completed_at = completion.await.expect("completion timestamp");
+        assert!(completed_at > 0);
+
+        server.shutdown().await;
+    }
+
+    #[tokio::test]
+    async fn read_http_request_returns_after_header_terminator() {
+        let listener = TcpListener::bind("127.0.0.1:0")
+            .await
+            .expect("bind test listener");
+        let addr = listener.local_addr().expect("listener address");
+        let (tx, rx) = oneshot::channel();
+        let server_task = tokio::spawn(async move {
+            let (mut stream, _) = listener.accept().await.expect("accept client");
+            let (request, body) = read_http_request(&mut stream).await;
+            let _ = tx.send((request, body));
+        });
+
+        let mut client = TcpStream::connect(addr)
+            .await
+            .expect("connect to test listener");
+        let request = "GET / HTTP/1.1\r\nHost: 127.0.0.1\r\n\r\n";
+        client
+            .write_all(request.as_bytes())
+            .await
+            .expect("write request");
+        let (received, body) = timeout(Duration::from_millis(200), rx)
+            .await
+            .expect("read_http_request timed out")
+            .expect("receive request");
+        assert_eq!(received, request);
+        assert!(body.is_empty());
+        drop(client);
+        let _ = server_task.await;
+    }
+
+    #[test]
+    fn parse_request_line_handles_valid_and_invalid() {
+        assert_eq!(parse_request_line(""), None);
+        assert_eq!(parse_request_line("BAD"), None);
+        assert_eq!(
+            parse_request_line("GET /v1/models HTTP/1.1"),
+            Some(("GET", "/v1/models"))
+        );
+    }
+
+    #[tokio::test]
+    async fn take_next_stream_consumes_in_lockstep() {
+        let (first_tx, first_rx) = oneshot::channel();
+        let (second_tx, second_rx) = oneshot::channel();
+        let state = TokioMutex::new(StreamingSseState {
+            responses: VecDeque::from(vec![
+                vec![StreamingSseChunk {
+                    gate: None,
+                    body: "first".to_string(),
+                }],
+                vec![StreamingSseChunk {
+                    gate: None,
+                    body: "second".to_string(),
+                }],
+            ]),
+            completions: VecDeque::from(vec![first_tx, second_tx]),
+        });
+
+        let (first_chunks, first_completion) =
+            take_next_stream(&state).await.expect("first stream");
+        assert_eq!(first_chunks[0].body, "first");
+        let _ = first_completion.send(11);
+        assert_eq!(first_rx.await.expect("first completion"), 11);
+
+        let (second_chunks, second_completion) =
+            take_next_stream(&state).await.expect("second stream");
+        assert_eq!(second_chunks[0].body, "second");
+        let _ = second_completion.send(22);
+        assert_eq!(second_rx.await.expect("second completion"), 22);
+
+        let third = take_next_stream(&state).await;
+        assert!(third.is_none());
+    }
+
+    #[tokio::test]
+    async fn shutdown_terminates_accept_loop() {
+        let (server, _) = start_streaming_sse_server(Vec::new()).await;
+        let shutdown = timeout(Duration::from_millis(200), server.shutdown()).await;
+        assert!(shutdown.is_ok());
+    }
+}
diff --git a/codex-rs/core/tests/common/test_codex.rs b/codex-rs/core/tests/common/test_codex.rs
index 7a12a24a69..59379d7686 100644
--- a/codex-rs/core/tests/common/test_codex.rs
+++ b/codex-rs/core/tests/common/test_codex.rs
@@ -25,6 +25,7 @@ use wiremock::MockServer;
 use crate::load_default_config_for_test;
 use crate::responses::get_responses_request_bodies;
 use crate::responses::start_mock_server;
+use crate::streaming_sse::StreamingSseServer;
 use crate::wait_for_event;
 
 type ConfigMutator = dyn FnOnce(&mut Config) + Send;
@@ -89,6 +90,16 @@ impl TestCodexBuilder {
         self.build_with_home(server, home, None).await
     }
 
+    pub async fn build_with_streaming_server(
+        &mut self,
+        server: &StreamingSseServer,
+    ) -> anyhow::Result<TestCodex> {
+        let base_url = server.uri();
+        let home = Arc::new(TempDir::new()?);
+        self.build_with_home_and_base_url(format!("{base_url}/v1"), home, None)
+            .await
+    }
+
     pub async fn resume(
         &mut self,
         server: &wiremock::MockServer,
@@ -104,8 +115,28 @@ impl TestCodexBuilder {
         home: Arc<TempDir>,
         resume_from: Option<PathBuf>,
     ) -> anyhow::Result<TestCodex> {
-        let (config, cwd) = self.prepare_config(server, &home).await?;
+        let base_url = format!("{}/v1", server.uri());
+        let (config, cwd) = self.prepare_config(base_url, &home).await?;
+        self.build_from_config(config, cwd, home, resume_from).await
+    }
 
+    async fn build_with_home_and_base_url(
+        &mut self,
+        base_url: String,
+        home: Arc<TempDir>,
+        resume_from: Option<PathBuf>,
+    ) -> anyhow::Result<TestCodex> {
+        let (config, cwd) = self.prepare_config(base_url, &home).await?;
+        self.build_from_config(config, cwd, home, resume_from).await
+    }
+
+    async fn build_from_config(
+        &mut self,
+        config: Config,
+        cwd: Arc<TempDir>,
+        home: Arc<TempDir>,
+        resume_from: Option<PathBuf>,
+    ) -> anyhow::Result<TestCodex> {
         let auth = self.auth.clone();
         let conversation_manager = ConversationManager::with_models_provider_and_home(
             auth.clone(),
@@ -139,11 +170,11 @@ impl TestCodexBuilder {
 
     async fn prepare_config(
         &mut self,
-        server: &wiremock::MockServer,
+        base_url: String,
         home: &TempDir,
     ) -> anyhow::Result<(Config, Arc<TempDir>)> {
         let model_provider = ModelProviderInfo {
-            base_url: Some(format!("{}/v1", server.uri())),
+            base_url: Some(base_url),
             ..built_in_model_providers()["openai"].clone()
         };
         let cwd = Arc::new(TempDir::new()?);
diff --git a/codex-rs/core/tests/suite/remote_models.rs b/codex-rs/core/tests/suite/remote_models.rs
index bf01196c78..c139964d07 100644
--- a/codex-rs/core/tests/suite/remote_models.rs
+++ b/codex-rs/core/tests/suite/remote_models.rs
@@ -41,6 +41,7 @@ use core_test_support::skip_if_no_network;
 use core_test_support::skip_if_sandbox;
 use core_test_support::wait_for_event;
 use core_test_support::wait_for_event_match;
+use pretty_assertions::assert_eq;
 use serde_json::json;
 use tempfile::TempDir;
 use tokio::time::Duration;
@@ -298,6 +299,108 @@ async fn remote_models_apply_remote_base_instructions() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn remote_models_preserve_builtin_presets() -> Result<()> {
+    skip_if_no_network!(Ok(()));
+    skip_if_sandbox!(Ok(()));
+
+    let server = MockServer::start().await;
+    let remote_model = test_remote_model("remote-alpha", ModelVisibility::List, 0);
+    let models_mock = mount_models_once(
+        &server,
+        ModelsResponse {
+            models: vec![remote_model.clone()],
+            etag: String::new(),
+        },
+    )
+    .await;
+
+    let codex_home = TempDir::new()?;
+    let mut config = load_default_config_for_test(&codex_home);
+    config.features.enable(Feature::RemoteModels);
+
+    let auth = CodexAuth::from_api_key("dummy");
+    let provider = ModelProviderInfo {
+        base_url: Some(format!("{}/v1", server.uri())),
+        ..built_in_model_providers()["openai"].clone()
+    };
+    let manager = ModelsManager::with_provider(
+        codex_core::auth::AuthManager::from_auth_for_testing(auth),
+        provider,
+    );
+
+    manager
+        .refresh_available_models(&config)
+        .await
+        .expect("refresh succeeds");
+
+    let available = manager.list_models(&config).await;
+    let remote = available
+        .iter()
+        .find(|model| model.model == "remote-alpha")
+        .expect("remote model should be listed");
+    let mut expected_remote: ModelPreset = remote_model.into();
+    expected_remote.is_default = true;
+    assert_eq!(*remote, expected_remote);
+    assert!(
+        available
+            .iter()
+            .any(|model| model.model == "gpt-5.1-codex-max"),
+        "builtin presets should remain available after refresh"
+    );
+    assert_eq!(
+        models_mock.requests().len(),
+        1,
+        "expected a single /models request"
+    );
+
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn remote_models_hide_picker_only_models() -> Result<()> {
+    skip_if_no_network!(Ok(()));
+    skip_if_sandbox!(Ok(()));
+
+    let server = MockServer::start().await;
+    let remote_model = test_remote_model("codex-auto-balanced", ModelVisibility::Hide, 0);
+    mount_models_once(
+        &server,
+        ModelsResponse {
+            models: vec![remote_model],
+            etag: String::new(),
+        },
+    )
+    .await;
+
+    let codex_home = TempDir::new()?;
+    let mut config = load_default_config_for_test(&codex_home);
+    config.features.enable(Feature::RemoteModels);
+
+    let auth = CodexAuth::create_dummy_chatgpt_auth_for_testing();
+    let provider = ModelProviderInfo {
+        base_url: Some(format!("{}/v1", server.uri())),
+        ..built_in_model_providers()["openai"].clone()
+    };
+    let manager = ModelsManager::with_provider(
+        codex_core::auth::AuthManager::from_auth_for_testing(auth),
+        provider,
+    );
+
+    let selected = manager.get_model(&None, &config).await;
+    assert_eq!(selected, "gpt-5.1-codex-max");
+
+    let available = manager.list_models(&config).await;
+    assert!(
+        available
+            .iter()
+            .all(|model| model.model != "codex-auto-balanced"),
+        "hidden models should not appear in the picker list"
+    );
+
+    Ok(())
+}
+
 async fn wait_for_model_available(
     manager: &Arc<ModelsManager>,
     slug: &str,
@@ -362,3 +465,32 @@ where
         conversation_manager,
     })
 }
+
+fn test_remote_model(slug: &str, visibility: ModelVisibility, priority: i32) -> ModelInfo {
+    ModelInfo {
+        slug: slug.to_string(),
+        display_name: format!("{slug} display"),
+        description: Some(format!("{slug} description")),
+        default_reasoning_level: ReasoningEffort::Medium,
+        supported_reasoning_levels: vec![ReasoningEffortPreset {
+            effort: ReasoningEffort::Medium,
+            description: ReasoningEffort::Medium.to_string(),
+        }],
+        shell_type: ConfigShellToolType::ShellCommand,
+        visibility,
+        minimal_client_version: ClientVersion(0, 1, 0),
+        supported_in_api: true,
+        priority,
+        upgrade: None,
+        base_instructions: None,
+        supports_reasoning_summaries: false,
+        support_verbosity: false,
+        default_verbosity: None,
+        apply_patch_tool_type: None,
+        truncation_policy: TruncationPolicyConfig::bytes(10_000),
+        supports_parallel_tool_calls: false,
+        context_window: None,
+        reasoning_summary_format: ReasoningSummaryFormat::None,
+        experimental_supported_tools: Vec::new(),
+    }
+}
diff --git a/codex-rs/core/tests/suite/shell_command.rs b/codex-rs/core/tests/suite/shell_command.rs
index 10e972b3de..34124b35dc 100644
--- a/codex-rs/core/tests/suite/shell_command.rs
+++ b/codex-rs/core/tests/suite/shell_command.rs
@@ -13,10 +13,15 @@ use core_test_support::test_codex::TestCodexHarness;
 use core_test_support::test_codex::test_codex;
 use serde_json::json;
 
-fn shell_responses(call_id: &str, command: &str, login: Option<bool>) -> Vec<String> {
+fn shell_responses_with_timeout(
+    call_id: &str,
+    command: &str,
+    login: Option<bool>,
+    timeout_ms: i64,
+) -> Vec<String> {
     let args = json!({
         "command": command,
-        "timeout_ms": 2_000,
+        "timeout_ms": timeout_ms,
         "login": login,
     });
 
@@ -36,6 +41,10 @@ fn shell_responses(call_id: &str, command: &str, login: Option<bool>) -> Vec<Str
     ]
 }
 
+fn shell_responses(call_id: &str, command: &str, login: Option<bool>) -> Vec<String> {
+    shell_responses_with_timeout(call_id, command, login, 2_000)
+}
+
 async fn shell_command_harness_with(
     configure: impl FnOnce(TestCodexBuilder) -> TestCodexBuilder,
 ) -> Result<TestCodexHarness> {
@@ -54,6 +63,20 @@ async fn mount_shell_responses(
     mount_sse_sequence(harness.server(), shell_responses(call_id, command, login)).await;
 }
 
+async fn mount_shell_responses_with_timeout(
+    harness: &TestCodexHarness,
+    call_id: &str,
+    command: &str,
+    login: Option<bool>,
+    timeout_ms: i64,
+) {
+    mount_sse_sequence(
+        harness.server(),
+        shell_responses_with_timeout(call_id, command, login, timeout_ms),
+    )
+    .await;
+}
+
 fn assert_shell_command_output(output: &str, expected: &str) -> Result<()> {
     let normalized_output = output
         .replace("\r\n", "\n")
@@ -172,3 +195,32 @@ async fn pipe_output_without_login() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn shell_command_times_out_with_timeout_ms() -> anyhow::Result<()> {
+    skip_if_no_network!(Ok(()));
+
+    let harness = shell_command_harness_with(|builder| builder.with_model("gpt-5.1")).await?;
+
+    let call_id = "shell-command-timeout";
+    let command = if cfg!(windows) {
+        "timeout /t 5"
+    } else {
+        "sleep 5"
+    };
+    mount_shell_responses_with_timeout(&harness, call_id, command, None, 200).await;
+    harness
+        .submit("run a long command with a short timeout")
+        .await?;
+
+    let output = harness.function_call_stdout(call_id).await;
+    let normalized_output = output
+        .replace("\r\n", "\n")
+        .replace('\r', "\n")
+        .trim_end_matches('\n')
+        .to_string();
+    let expected_pattern = r"(?s)^Exit code: 124\nWall time: [0-9]+(?:\.[0-9]+)? seconds\nOutput:\ncommand timed out after [0-9]+ milliseconds\n?$";
+    assert_regex_match(expected_pattern, &normalized_output);
+
+    Ok(())
+}
diff --git a/codex-rs/core/tests/suite/tool_parallelism.rs b/codex-rs/core/tests/suite/tool_parallelism.rs
index abb55f3a14..0ec5221f40 100644
--- a/codex-rs/core/tests/suite/tool_parallelism.rs
+++ b/codex-rs/core/tests/suite/tool_parallelism.rs
@@ -1,6 +1,7 @@
 #![cfg(not(target_os = "windows"))]
 #![allow(clippy::unwrap_used)]
 
+use std::fs;
 use std::time::Duration;
 use std::time::Instant;
 
@@ -13,16 +14,22 @@ use codex_protocol::user_input::UserInput;
 use core_test_support::responses::ev_assistant_message;
 use core_test_support::responses::ev_completed;
 use core_test_support::responses::ev_function_call;
+use core_test_support::responses::ev_response_created;
+use core_test_support::responses::ev_shell_command_call_with_args;
 use core_test_support::responses::mount_sse_once;
 use core_test_support::responses::mount_sse_sequence;
 use core_test_support::responses::sse;
 use core_test_support::responses::start_mock_server;
 use core_test_support::skip_if_no_network;
+use core_test_support::streaming_sse::StreamingSseChunk;
+use core_test_support::streaming_sse::start_streaming_sse_server;
 use core_test_support::test_codex::TestCodex;
 use core_test_support::test_codex::test_codex;
 use core_test_support::wait_for_event;
+use pretty_assertions::assert_eq;
 use serde_json::Value;
 use serde_json::json;
+use tokio::sync::oneshot;
 
 async fn run_turn(test: &TestCodex, prompt: &str) -> anyhow::Result<()> {
     let session_model = test.session_configured.model.clone();
@@ -280,3 +287,123 @@ async fn tool_results_grouped() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn shell_tools_start_before_response_completed_when_stream_delayed() -> anyhow::Result<()> {
+    skip_if_no_network!(Ok(()));
+
+    let output_file = tempfile::NamedTempFile::new()?;
+    let output_path = output_file.path();
+    let first_response_id = "resp-1";
+    let second_response_id = "resp-2";
+
+    let command = format!(
+        "perl -MTime::HiRes -e 'print int(Time::HiRes::time()*1000), \"\\n\"' >> \"{}\"",
+        output_path.display()
+    );
+    let args = json!({
+        "command": command,
+        "timeout_ms": 1_000,
+    });
+
+    let first_chunk = sse(vec![
+        ev_response_created(first_response_id),
+        ev_shell_command_call_with_args("call-1", &args),
+        ev_shell_command_call_with_args("call-2", &args),
+        ev_shell_command_call_with_args("call-3", &args),
+        ev_shell_command_call_with_args("call-4", &args),
+    ]);
+    let second_chunk = sse(vec![ev_completed(first_response_id)]);
+    let follow_up = sse(vec![
+        ev_assistant_message("msg-1", "done"),
+        ev_completed(second_response_id),
+    ]);
+
+    let (first_gate_tx, first_gate_rx) = oneshot::channel();
+    let (completion_gate_tx, completion_gate_rx) = oneshot::channel();
+    let (follow_up_gate_tx, follow_up_gate_rx) = oneshot::channel();
+    let (streaming_server, completion_receivers) = start_streaming_sse_server(vec![
+        vec![
+            StreamingSseChunk {
+                gate: Some(first_gate_rx),
+                body: first_chunk,
+            },
+            StreamingSseChunk {
+                gate: Some(completion_gate_rx),
+                body: second_chunk,
+            },
+        ],
+        vec![StreamingSseChunk {
+            gate: Some(follow_up_gate_rx),
+            body: follow_up,
+        }],
+    ])
+    .await;
+
+    let mut builder = test_codex().with_model("gpt-5.1");
+    let test = builder
+        .build_with_streaming_server(&streaming_server)
+        .await?;
+
+    let session_model = test.session_configured.model.clone();
+    test.codex
+        .submit(Op::UserTurn {
+            items: vec![UserInput::Text {
+                text: "stream delayed completion".into(),
+            }],
+            final_output_json_schema: None,
+            cwd: test.cwd.path().to_path_buf(),
+            approval_policy: AskForApproval::Never,
+            sandbox_policy: SandboxPolicy::DangerFullAccess,
+            model: session_model,
+            effort: None,
+            summary: ReasoningSummary::Auto,
+        })
+        .await?;
+
+    let _ = first_gate_tx.send(());
+    let _ = follow_up_gate_tx.send(());
+
+    let timestamps = tokio::time::timeout(Duration::from_secs(1), async {
+        loop {
+            let contents = fs::read_to_string(output_path)?;
+            let timestamps = contents
+                .lines()
+                .filter(|line| !line.trim().is_empty())
+                .map(|line| {
+                    line.trim()
+                        .parse::<i64>()
+                        .map_err(|err| anyhow::anyhow!("invalid timestamp {line:?}: {err}"))
+                })
+                .collect::<Result<Vec<_>, _>>()?;
+            if timestamps.len() == 4 {
+                return Ok::<_, anyhow::Error>(timestamps);
+            }
+            tokio::time::sleep(Duration::from_millis(10)).await;
+        }
+    })
+    .await??;
+
+    let _ = completion_gate_tx.send(());
+    wait_for_event(&test.codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;
+
+    let mut completion_iter = completion_receivers.into_iter();
+    let completed_at = completion_iter
+        .next()
+        .expect("completion receiver missing")
+        .await
+        .expect("completion timestamp missing");
+    let count = i64::try_from(timestamps.len()).expect("timestamp count fits in i64");
+    assert_eq!(count, 4);
+
+    for timestamp in timestamps {
+        assert!(
+            timestamp < completed_at,
+            "timestamp {timestamp} should be before completed {completed_at}"
+        );
+    }
+
+    streaming_server.shutdown().await;
+
+    Ok(())
+}
diff --git a/codex-rs/tui2/Cargo.toml b/codex-rs/tui2/Cargo.toml
index fd542feda9..eb4e9cebde 100644
--- a/codex-rs/tui2/Cargo.toml
+++ b/codex-rs/tui2/Cargo.toml
@@ -106,8 +106,8 @@ arboard = { workspace = true }
 
 
 [dev-dependencies]
-codex-core = { workspace = true, features = ["test-support"] }
 assert_matches = { workspace = true }
+codex-core = { workspace = true, features = ["test-support"] }
 chrono = { workspace = true, features = ["serde"] }
 insta = { workspace = true }
 pretty_assertions = { workspace = true }
diff --git a/codex-rs/tui2/docs/streaming_wrapping_design.md b/codex-rs/tui2/docs/streaming_wrapping_design.md
new file mode 100644
index 0000000000..28937c377f
--- /dev/null
+++ b/codex-rs/tui2/docs/streaming_wrapping_design.md
@@ -0,0 +1,85 @@
+# Streaming Markdown Wrapping & Animation – TUI2 Notes
+
+This document mirrors the original `tui/streaming_wrapping_design.md` and
+captures how the same concerns apply to the new `tui2` crate. It exists so that
+future viewport and streaming work in TUI2 can rely on the same context without
+having to cross‑reference the legacy TUI implementation.
+
+At a high level, the design constraints are the same:
+
+- Streaming agent responses are rendered incrementally, with an animation loop
+  that reveals content over time.
+- Non‑streaming history cells are rendered width‑agnostically and wrapped only
+  at display time, so they reflow correctly when the terminal is resized.
+- Streaming content should eventually follow the same “wrap on display” model so
+  the transcript reflows consistently across width changes, without regressing
+  animation or markdown semantics.
+
+## 1. Where streaming is implemented in TUI2
+
+TUI2 keeps the streaming pipeline conceptually aligned with the legacy TUI but
+in a separate crate:
+
+- `tui2/src/markdown_stream.rs` implements the markdown streaming collector and
+  animation controller for agent deltas.
+- `tui2/src/chatwidget.rs` integrates streamed content into the transcript via
+  `HistoryCell` implementations.
+- `tui2/src/history_cell.rs` provides the concrete history cell types used by
+  the inline transcript and overlays.
+- `tui2/src/wrapping.rs` contains the shared text wrapping utilities used by
+  both streaming and non‑streaming render paths:
+  - `RtOptions` describes viewport‑aware wrapping (width, indents, algorithm).
+  - `word_wrap_line`, `word_wrap_lines`, and `word_wrap_lines_borrowed` provide
+    span‑aware wrapping that preserves markdown styling and emoji width.
+
+As in the original TUI, the key tension is between:
+
+- **Pre‑wrapping streamed content at commit time** (simpler animation, but
+  baked‑in splits that don’t reflow), and
+- **Deferring wrapping to render time** (better reflow, but requires a more
+  sophisticated streaming cell model or recomputation on each frame).
+
+## 2. Current behavior and limitations
+
+TUI2 is intentionally conservative for now:
+
+- Streaming responses use the same markdown streaming and wrapping utilities as
+  the legacy TUI, with width decisions made near the streaming collector.
+- The transcript viewport (`App::render_transcript_cells` in
+  `tui2/src/app.rs`) always uses `word_wrap_lines_borrowed` against the
+  current `Rect` width, so:
+  - Non‑streaming cells reflow naturally on resize.
+  - Streamed cells respect whatever wrapping was applied when their lines were
+    constructed, and may not fully “un‑wrap” if that work happened at a fixed
+    width earlier in the pipeline.
+
+This means TUI2 shares the same fundamental limitation documented in the
+original design note: streamed paragraphs can retain historical wrap decisions
+made at the time they were streamed, even if the viewport later grows wider.
+
+## 3. Design directions (forward‑looking)
+
+The options outlined in the legacy document apply here as well:
+
+1. **Keep the current behavior but clarify tests and documentation.**
+   - Ensure tests in `tui2/src/markdown_stream.rs`, `tui2/src/markdown_render.rs`,
+     `tui2/src/history_cell.rs`, and `tui2/src/wrapping.rs` encode the current
+     expectations around streaming, wrapping, and emoji / markdown styling.
+2. **Move towards width‑agnostic streaming cells.**
+   - Introduce a dedicated streaming history cell that stores the raw markdown
+     buffer and lets `HistoryCell::display_lines(width)` perform both markdown
+     rendering and wrapping based on the current viewport width.
+   - Keep the commit animation logic expressed in terms of “logical” positions
+     (e.g., number of tokens or lines committed) rather than pre‑wrapped visual
+     lines at a fixed width.
+3. **Hybrid “visual line count” model.**
+   - Track committed visual lines as a scalar and re‑render the streamed prefix
+     at the current width, revealing only the first `N` visual lines on each
+     animation tick.
+
+TUI2 does not yet implement these refactors; it intentionally stays close to
+the legacy behavior while the viewport work (scrolling, selection, exit
+transcripts) is being ported. This document exists to make that trade‑off
+explicit for TUI2 and to provide a natural home for any TUI2‑specific streaming
+wrapping notes as the design evolves.
+
diff --git a/codex-rs/tui2/docs/tui_viewport_and_history.md b/codex-rs/tui2/docs/tui_viewport_and_history.md
new file mode 100644
index 0000000000..8485e93646
--- /dev/null
+++ b/codex-rs/tui2/docs/tui_viewport_and_history.md
@@ -0,0 +1,454 @@
+# TUI2 Viewport, Transcript, and History – Design Notes
+
+This document describes the viewport and history model we are implementing in the new
+`codex-rs/tui2` crate. It builds on lessons from the legacy TUI and explains why we moved away
+from directly writing history into terminal scrollback.
+
+The target audience is Codex developers and curious contributors who want to understand or
+critique how TUI2 owns its viewport, scrollback, and suspend behavior.
+
+Unless stated otherwise, references to “the TUI” in this document mean the TUI2 implementation;
+when we mean the legacy TUI specifically, we call it out explicitly.
+
+---
+
+## 1. Problem Overview
+
+Historically, the legacy TUI tried to “cooperate” with the terminal’s own scrollback:
+
+- The inline viewport sat somewhere above the bottom of the screen.
+- When new history arrived, we tried to insert it directly into the terminal scrollback above the
+  viewport.
+- On certain transitions (e.g. switching sessions, overlays), we cleared and re‑wrote portions of
+  the screen from scratch.
+
+This had several failure modes:
+
+- **Terminal‑dependent behavior.**
+  - Different terminals handle scroll regions, clears, and resize semantics differently.
+  - What looked correct in one terminal could drop or duplicate content in another.
+
+- **Resizes and layout churn.**
+  - The TUI reacts to resizes, focus changes, and overlay transitions.
+  - When the viewport moved or its size changed, our attempts to keep scrollback “aligned” with the
+    in‑memory history could go out of sync.
+  - In practice this meant:
+    - Some lines were lost or overwritten.
+    - Others were duplicated or appeared in unexpected places.
+
+- **“Clear and rewrite everything” didn’t save us.**
+  - We briefly tried a strategy of clearing large regions (or the full screen) and re‑rendering
+    history when the layout changed.
+  - This ran into two issues:
+    - Terminals treat full clears differently. For example, Terminal.app often leaves the cleared
+      screen as a “page” at the top of scrollback, some terminals interpret only a subset of the
+      ANSI clear/scrollback codes, and others (like iTerm2) gate “clear full scrollback” behind
+      explicit user consent.
+    - Replaying a long session is expensive and still subject to timing/race conditions with user
+      output (e.g. shell prompts) when we weren’t in alt screen.
+
+The net result: the legacy TUI could not reliably guarantee “the history you see on screen is complete, in
+order, and appears exactly once” across terminals, resizes, suspend/resume, and overlay transitions.
+
+---
+
+## 2. Goals
+
+The redesign is guided by a few explicit goals:
+
+1. **Codex, not the terminal, owns the viewport.**
+   - The in‑memory transcript (a list of history entries) is the single source of truth for what’s
+     on screen.
+   - The TUI decides how to map that transcript into the current viewport; scrollback becomes an
+     output target, not an extra data structure we try to maintain.
+
+2. **History must be correct, ordered, and never silently dropped.**
+   - Every logical history cell should either:
+     - Be visible in the TUI, or
+     - Have been printed into scrollback as part of a suspend/exit flow.
+   - We would rather (rarely) duplicate content than risk losing it.
+
+3. **Avoid unnecessary duplication.**
+   - When emitting history to scrollback (on suspend or exit), print each logical cell’s content at
+     most once.
+   - Streaming cells are allowed to be “re‑seen” as they grow, but finished cells should not keep
+     reappearing.
+
+4. **Behave sensibly under resizes.**
+   - TUI rendering should reflow to the current width on every frame.
+   - History printed to scrollback may have been wrapped at different widths over time; that is
+     acceptable, but it must not cause missing content or unbounded duplication.
+
+5. **Suspend/alt‑screen interaction is predictable.**
+   - `Ctrl+Z` should:
+     - Cleanly exit alt screen, if active.
+     - Print a consistent transcript prefix into normal scrollback.
+     - Resume with the TUI fully redrawn, without stale artifacts.
+
+---
+
+## 3. New Viewport & Transcript Model
+
+### 3.1 Transcript as a logical sequence of cells
+
+At a high level, the TUI transcript is a list of “cells”, each representing one logical thing in
+the conversation:
+
+- A user prompt (with padding and a distinct background).
+- An agent response (which may arrive in multiple streaming chunks).
+- System or info rows (session headers, migration banners, reasoning summaries, etc.).
+
+Each cell knows how to draw itself for a given width: how many lines it needs, what prefixes to
+use, how to style its content. The transcript itself is purely logical:
+
+- It has no scrollback coordinates or terminal state baked into it.
+- It can be re‑rendered for any viewport width.
+
+The TUI’s job is to take this logical sequence and decide how much of it fits into the current
+viewport, and how it should be wrapped and styled on screen.
+
+### 3.2 Building viewport lines from the transcript
+
+To render the main transcript area above the composer, the TUI:
+
+1. Defines a “transcript region” as the full frame minus the height of the bottom input area.
+2. Flattens all cells into a list of visual lines, remembering for each visual line which cell it
+   came from and which line within that cell it corresponds to.
+3. Uses this flattened list plus a scroll position to decide which visual line should appear at the
+   top of the region.
+4. Clears the transcript region and draws the visible slice of lines into it.
+5. For user messages, paints the entire row background (including padding lines) so the user block
+   stands out even when it does not fill the whole width.
+6. Applies selection styling and other overlays on top of the rendered lines.
+
+Scrolling (mouse wheel, PgUp/PgDn, Home/End) operates entirely in terms of these flattened lines
+and the current scroll anchor. The terminal’s own scrollback is not part of this calculation; it
+only ever sees fully rendered frames.
+
+### 3.3 Alternate screen, overlays, and redraw guarantees
+
+The TUI uses the terminal’s alternate screen for:
+
+- The main interactive chat session (so the viewport can cover the full terminal).
+- Full‑screen overlays such as the transcript pager, diff view, model migration screen, and
+  onboarding.
+
+Conceptually:
+
+- Entering alt screen:
+  - Switches the terminal into alt screen and expands the viewport to cover the full terminal.
+  - Clears that alt‑screen buffer.
+
+- Leaving alt screen:
+  - Disables “alternate scroll” so mouse wheel events behave predictably.
+  - Returns to the normal screen.
+
+- On leaving overlays and on resuming from suspend, the TUI viewport is explicitly cleared and fully
+  redrawn:
+  - This prevents stale overlay content or shell output from lingering in the TUI area.
+  - The next frame reconstructs the UI entirely from the in‑memory transcript and other state, not
+    from whatever the terminal happened to remember.
+
+Alt screen is therefore treated as a temporary render target. The only authoritative copy of the UI
+is the in‑memory state.
+
+---
+
+## 4. Mouse, Selection, and Scrolling
+
+Mouse interaction is a first‑class part of the new design:
+
+- **Scrolling.**
+  - Mouse wheel scrolls the transcript in fixed line increments.
+  - Keyboard shortcuts (PgUp/PgDn/Home/End) use the same scroll model, so the footer can show
+    consistent hints regardless of input device.
+
+- **Selection.**
+  - A click‑and‑drag gesture defines a linear text selection in terms of the flattened transcript
+    lines (not raw buffer coordinates).
+  - Selection tracks the _content_ rather than a fixed screen row. When the transcript scrolls, the
+    selection moves along with the underlying lines instead of staying glued to a particular Y
+    position.
+  - The selection only covers the “transcript text” area; it intentionally skips the left gutter
+    that we use for bullets/prefixes.
+
+- **Copy.**
+  - When the user triggers copy, the TUI re‑renders just the transcript region off‑screen using the
+    same wrapping as the visible view.
+  - It then walks the selected lines and columns in that off‑screen buffer to reconstruct the exact
+    text region the user highlighted (including internal spaces and empty lines).
+  - That text is sent to the system clipboard and a status footer indicates success or failure.
+
+Because scrolling, selection, and copy all operate on the same flattened transcript representation,
+they remain consistent even as the viewport resizes or the chat composer grows/shrinks. Owning our
+own scrolling also means we must own mouse interactions end‑to‑end: if we left scrolling entirely
+to the terminal, we could not reliably line up selections with transcript content or avoid
+accidentally copying gutter/margin characters instead of just the conversation text.
+
+---
+
+## 5. Printing History to Scrollback
+
+We still want the final session (and suspend points) to appear in the user’s normal scrollback, but
+we no longer try to maintain scrollback in lock‑step with the TUI frame. Instead, we treat
+scrollback as an **append‑only log** of logical transcript cells.
+
+In practice this means:
+
+- The TUI may print history both when you suspend (`Ctrl+Z`) and when you exit.
+- Some users may prefer to only print on exit (for example to keep scrollback quieter during long
+  sessions). The current design anticipates gating suspend‑time printing behind a config toggle so
+  that this behavior can be made opt‑in or opt‑out without touching the core viewport logic, but
+  that switch has not been implemented yet.
+
+### 5.1 Cell‑based high‑water mark
+
+Internally, the TUI keeps a simple “high‑water mark” for history printing:
+
+- Think of this as “how many cells at the front of the transcript have already been sent to
+  scrollback.”
+- It is just a counter over the logical transcript, not over wrapped lines.
+- It moves forward only when we have actually printed more history.
+
+This means we never try to guess “how many terminal lines have already been printed”; we only
+remember that “the first N logical entries are done.”
+
+### 5.2 Rendering new cells for scrollback
+
+When we need to print history (on suspend or exit), we:
+
+1. Take the suffix of the transcript that lies beyond the high‑water mark.
+2. Render just that suffix into styled lines at the **current** terminal width.
+3. Write those lines to stdout.
+4. Advance the high‑water mark to include all cells we just printed.
+
+Older cells are never re‑rendered for scrollback; they remain in whatever wrapping they had when
+they were first printed. This avoids the line‑count–based bugs we had before while still allowing
+the on‑screen TUI to reflow freely.
+
+### 5.3 Suspend (`Ctrl+Z`) flow
+
+On suspend (typically `Ctrl+Z` on Unix):
+
+- Before yielding control back to the shell, the TUI:
+  - Leaves alt screen if it is active and restores normal terminal modes.
+  - Determines which transcript cells have not yet been printed and renders them for the current
+    width.
+  - Prints those new lines once into normal scrollback.
+  - Marks those cells as printed in the high‑water mark.
+  - Finally, sends the process to the background.
+
+On `fg`, the process resumes, re‑enters TUI modes, and redraws the viewport from the in‑memory
+transcript. The history printed during suspend stays in scrollback and is not touched again.
+
+### 5.4 Exit flow
+
+When the TUI exits, we follow the same principle:
+
+- We compute the suffix of the transcript that has not yet been printed (taking into account any
+  prior suspends).
+- We render just that suffix to styled lines at the current width.
+- The outer `main` function leaves alt screen, restores the terminal, and prints those lines, plus a
+  blank line and token usage summary.
+
+If you never suspended, exit prints the entire transcript once. If you did suspend one or more
+times, exit prints only the cells appended after the last suspend. In both cases, each logical
+conversation entry reaches scrollback exactly once.
+
+---
+
+## 6. Streaming, Width Changes, and Tradeoffs
+
+### 6.1 Streaming cells
+
+Streaming agent responses are represented as a sequence of history entries:
+
+- The first chunk produces a “first line” entry for the message.
+- Subsequent chunks produce continuation entries that extend that message.
+
+From the history/scrollback perspective:
+
+- Each streaming chunk is just another entry in the logical transcript.
+- The high‑water mark is a simple count of how many entries at the _front_ of the transcript have
+  already been printed.
+- As new streaming chunks arrive, they are appended as new entries and will be included the next
+  time we print history on suspend or exit.
+
+We do **not** attempt to reprint or retroactively merge older chunks. In scrollback you will see the
+streaming response as a series of discrete blocks, matching the internal history structure.
+
+Today, streaming rendering still “bakes in” some width at the time chunks are committed: line breaks
+for the streaming path are computed using the width that was active at the time, and stored in the
+intermediate representation. This is a known limitation and is called out in more detail in
+`codex-rs/tui2/docs/streaming_wrapping_design.md`; a follow‑up change will make streaming behavior
+match the rest of the transcript more closely (wrap only at display time, not at commit time).
+
+### 6.2 Width changes over time
+
+Because we now use a **cell‑level** high‑water mark instead of a visual line‑count, width changes
+are handled gracefully:
+
+- On every suspend/exit, we render the not‑yet‑printed suffix of the transcript at the **current**
+  width and append those lines.
+- Previously printed entries remain in scrollback with whatever wrapping they had at the time they
+  were printed.
+- We no longer rely on “N lines printed before, therefore skip N lines of the newly wrapped
+  transcript,” which was the source of dropped and duplicated content when widths changed.
+
+This does mean scrollback can contain older cells wrapped for narrower or wider widths than the
+final terminal size, but:
+
+- Each logical cell’s content appears exactly once.
+- New cells are append‑only and never overwrite or implicitly “shrink” earlier content.
+- The on‑screen TUI always reflows to the current width independently of scrollback.
+
+If we later choose to also re‑emit the “currently streaming” cell when printing on suspend (to make
+sure the latest chunk of a long answer is always visible in scrollback), that would intentionally
+duplicate a small number of lines at the boundary of that cell. The design assumes any such behavior
+would be controlled by configuration (for example, by disabling suspend‑time printing entirely for
+users who prefer only exit‑time output).
+
+### 6.3 Why not reflow scrollback?
+
+In theory we could try to reflow already‑printed content when widths change by:
+
+- Recomputing the entire transcript at the new width, and
+- Printing diffs that “rewrite” old regions in scrollback.
+
+In practice, this runs into the same issues that motivated the redesign:
+
+- Terminals treat full clears and scroll regions differently.
+- There is no portable way to “rewrite” arbitrary portions of scrollback above the visible buffer.
+- Interleaving user output (e.g. shell prompts after suspend) makes it impossible to reliably
+  reconstruct the original scrollback structure.
+
+We therefore deliberately accept that scrollback is **append‑only** and not subject to reflow;
+correctness is measured in terms of logical transcript content, not pixel‑perfect layout.
+
+---
+
+## 7. Backtrack and Overlays (Context)
+
+While this document is focused on viewport and history, it’s worth mentioning a few related
+behaviors that rely on the same model.
+
+### 7.1 Transcript overlay and backtrack
+
+The transcript overlay (pager) is a full‑screen view of the same logical transcript:
+
+- When opened, it takes a snapshot of the current transcript and renders it in an alt‑screen
+  overlay.
+- Backtrack mode (`Esc` sequences) walks backwards through user messages in that snapshot and
+  highlights the candidate “edit from here” point.
+- Confirming a backtrack request forks the conversation on the server and trims the in‑memory
+  transcript so that only history up to the chosen user message remains, then re‑renders that prefix
+  in the main view.
+
+The overlay is purely a different _view_ of the same transcript; it never infers anything from
+scrollback.
+
+---
+
+## 8. Summary of Tradeoffs
+
+**What we gain:**
+
+- The TUI has a clear, single source of truth for history (the in‑memory transcript).
+- Viewport rendering is deterministic and independent of scrollback.
+- Suspend and exit flows:
+  - Print each logical history cell exactly once.
+  - Are robust to terminal width changes.
+  - Interact cleanly with alt screen and raw‑mode toggling.
+- Streaming, overlays, selection, and backtrack all share the same logical history model.
+- Because cells are always re‑rendered live from the transcript, per‑cell interactions can become
+  richer over time. Instead of treating the transcript as “dead text”, we can make individual
+  entries interactive after they are rendered: expanding or contracting tool calls, diffs, or
+  reasoning summaries in place, jum…truncated… \*\*\*
+
+---
+
+## 9. TUI2 Implementation Notes
+
+This section maps the design above onto the `codex-rs/tui2` crate so future viewport work has
+concrete code pointers.
+
+### 9.1 Transcript state and layout
+
+The main app struct (`codex-rs/tui2/src/app.rs`) tracks the transcript and viewport state with:
+
+- `transcript_cells: Vec<Arc<dyn HistoryCell>>` – the logical history.
+- `transcript_scroll: TranscriptScroll` – whether the viewport is pinned to the bottom or
+  anchored at a specific cell/line pair.
+- `transcript_selection: TranscriptSelection` – a selection expressed in screen coordinates over
+  the flattened transcript region.
+- `transcript_view_top` / `transcript_total_lines` – the current viewport’s top line index and
+  total number of wrapped lines for the inline transcript area.
+
+### 9.2 Rendering, wrapping, and selection
+
+`App::render_transcript_cells` defines the transcript region, builds flattened lines via
+`App::build_transcript_lines`, wraps them with `word_wrap_lines_borrowed` from
+`codex-rs/tui2/src/wrapping.rs`, and applies selection via `apply_transcript_selection` before
+writing to the frame buffer.
+
+Streaming wrapping details live in `codex-rs/tui2/docs/streaming_wrapping_design.md`.
+
+### 9.3 Input, selection, and footer state
+
+Mouse handling lives in `App::handle_mouse_event`, keyboard scrolling in
+`App::handle_key_event`, selection rendering in `App::apply_transcript_selection`, and copy in
+`App::copy_transcript_selection` plus `codex-rs/tui2/src/clipboard_copy.rs`. Scroll/selection UI
+state is forwarded through `ChatWidget::set_transcript_ui_state`,
+`BottomPane::set_transcript_ui_state`, and `ChatComposer::footer_props`, with footer text
+assembled in `codex-rs/tui2/src/bottom_pane/footer.rs`.
+
+### 9.4 Exit transcript output
+
+`App::run` returns `session_lines` on `AppExitInfo` after flattening with
+`App::build_transcript_lines` and converting to ANSI via `App::render_lines_to_ansi`. The CLI
+prints those lines before the token usage and resume hints.
+
+## 10. Future Work and Open Questions
+
+This section collects design questions that follow naturally from the current model and are worth
+explicit discussion before we commit to further UI changes.
+
+- **“Scroll mode” vs “live follow” UI.**
+  - We already distinguish “scrolled away from bottom” vs “following the latest output” in the
+    footer and scroll state. Do we need a more explicit “scroll mode vs live mode” affordance (e.g.,
+    a dedicated indicator or toggle), or is the current behavior sufficient and adding more chrome
+    would be noise?
+
+- **Ephemeral scroll indicator.**
+  - For long sessions, a more visible sense of “where am I?” could help. One option is a minimalist
+    scrollbar that appears while the user is actively scrolling and fades out when idle. A full
+    “mini‑map” is probably too heavy for a TUI given the limited vertical space, but we could
+    imagine adding simple markers along the scrollbar to show where prior prompts occurred, or
+    where text search matches are, without trying to render a full preview of the buffer.
+
+- **Selection affordances.**
+  - Today, the primary hint that selection is active is the reversed text and the “Ctrl+Y copy
+    selection” footer text. Do we want an explicit “Selecting… (Esc to cancel)” status while a drag
+    is in progress, or would that be redundant/clutter for most users?
+
+- **Suspend banners in scrollback.**
+  - When printing history on suspend, should we also emit a small banner such as
+    `--- codex suspended; history up to here ---` to make those boundaries obvious in scrollback?
+    This would slightly increase noise but could make multi‑suspend sessions easier to read.
+
+- **Configuring suspend printing behavior.**
+  - The design already assumes that suspend‑time printing can be gated by config. Questions to
+    resolve:
+    - Should printing on suspend be on or off by default?
+    - Should we support multiple modes (e.g., “off”, “print all new cells”, “print streaming cell
+      tail only”) or keep it binary?
+
+- **Streaming duplication at the edges.**
+  - If we later choose to always re‑emit the “currently streaming” message when printing on suspend,
+    we would intentionally allow a small amount of duplication at the boundary of that message (for
+    example, its last line appearing twice across suspends). Is that acceptable if it improves the
+    readability of long streaming answers in scrollback, and should the ability to disable
+    suspend‑time printing be our escape hatch for users who care about exact de‑duplication?\*\*\*
+
+---
+
diff --git a/codex-rs/tui2/src/app.rs b/codex-rs/tui2/src/app.rs
index bb4c632447..032a228ec4 100644
--- a/codex-rs/tui2/src/app.rs
+++ b/codex-rs/tui2/src/app.rs
@@ -3,10 +3,13 @@ use crate::app_event::AppEvent;
 use crate::app_event_sender::AppEventSender;
 use crate::bottom_pane::ApprovalRequest;
 use crate::chatwidget::ChatWidget;
+use crate::clipboard_copy;
+use crate::custom_terminal::Frame;
 use crate::diff_render::DiffSummary;
 use crate::exec_command::strip_bash_lc_and_escape;
 use crate::file_search::FileSearchManager;
 use crate::history_cell::HistoryCell;
+use crate::history_cell::UserHistoryCell;
 use crate::model_migration::ModelMigrationOutcome;
 use crate::model_migration::migration_copy_for_models;
 use crate::model_migration::run_model_migration_prompt;
@@ -19,6 +22,9 @@ use crate::skill_error_prompt::run_skill_error_prompt;
 use crate::tui;
 use crate::tui::TuiEvent;
 use crate::update_action::UpdateAction;
+use crate::wrapping::RtOptions;
+use crate::wrapping::word_wrap_line;
+use crate::wrapping::word_wrap_lines_borrowed;
 use codex_ansi_escape::ansi_escape_line;
 use codex_core::AuthManager;
 use codex_core::ConversationManager;
@@ -46,9 +52,14 @@ use color_eyre::eyre::WrapErr;
 use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;
 use crossterm::event::KeyEventKind;
+use crossterm::event::MouseButton;
+use ratatui::buffer::Buffer;
+use ratatui::layout::Rect;
 use ratatui::style::Stylize;
 use ratatui::text::Line;
+use ratatui::widgets::Clear;
 use ratatui::widgets::Paragraph;
+use ratatui::widgets::WidgetRef;
 use ratatui::widgets::Wrap;
 use std::collections::BTreeMap;
 use std::path::Path;
@@ -60,6 +71,7 @@ use std::thread;
 use std::time::Duration;
 use tokio::select;
 use tokio::sync::mpsc::unbounded_channel;
+use unicode_width::UnicodeWidthStr;
 
 #[cfg(not(debug_assertions))]
 use crate::history_cell::UpdateAvailableHistoryCell;
@@ -69,6 +81,12 @@ pub struct AppExitInfo {
     pub token_usage: TokenUsage,
     pub conversation_id: Option<ConversationId>,
     pub update_action: Option<UpdateAction>,
+    /// ANSI-styled transcript lines to print after the TUI exits.
+    ///
+    /// These lines are rendered against the same width as the final TUI
+    /// viewport and include styling (colors, bold, etc.) so that scrollback
+    /// preserves the visual structure of the on-screen transcript.
+    pub session_lines: Vec<String>,
 }
 
 impl From<AppExitInfo> for codex_tui::AppExitInfo {
@@ -268,6 +286,7 @@ async fn handle_model_migration_prompt_if_needed(
                     token_usage: TokenUsage::default(),
                     conversation_id: None,
                     update_action: None,
+                    session_lines: Vec::new(),
                 });
             }
         }
@@ -290,6 +309,12 @@ pub(crate) struct App {
 
     pub(crate) transcript_cells: Vec<Arc<dyn HistoryCell>>,
 
+    #[allow(dead_code)]
+    transcript_scroll: TranscriptScroll,
+    transcript_selection: TranscriptSelection,
+    transcript_view_top: usize,
+    transcript_total_lines: usize,
+
     // Pager overlay state (Transcript or Static like Diff)
     pub(crate) overlay: Option<Overlay>,
     pub(crate) deferred_history_lines: Vec<Line<'static>>,
@@ -314,6 +339,42 @@ pub(crate) struct App {
     skip_world_writable_scan_once: bool,
 }
 
+/// Scroll state for the inline transcript viewport.
+///
+/// This tracks whether the transcript is pinned to the latest line or anchored
+/// at a specific cell/line pair so later viewport changes can implement
+/// scrollback without losing the notion of "bottom".
+#[allow(dead_code)]
+#[derive(Debug, Clone, Copy, Default)]
+enum TranscriptScroll {
+    #[default]
+    ToBottom,
+    Scrolled {
+        cell_index: usize,
+        line_in_cell: usize,
+    },
+}
+/// Content-relative selection within the inline transcript viewport.
+///
+/// Selection endpoints are expressed in terms of flattened, wrapped transcript
+/// line indices and columns, so the highlight tracks logical conversation
+/// content even when the viewport scrolls or the terminal is resized.
+#[derive(Debug, Clone, Copy, Default)]
+struct TranscriptSelection {
+    anchor: Option<TranscriptSelectionPoint>,
+    head: Option<TranscriptSelectionPoint>,
+}
+
+/// A single endpoint of a transcript selection.
+///
+/// `line_index` is an index into the flattened wrapped transcript lines, and
+/// `column` is a zero-based column offset within that visual line, counted from
+/// the first content column to the right of the transcript gutter.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+struct TranscriptSelectionPoint {
+    line_index: usize,
+    column: u16,
+}
 impl App {
     async fn shutdown_current_conversation(&mut self) {
         if let Some(conversation_id) = self.chat_widget.conversation_id() {
@@ -433,6 +494,10 @@ impl App {
             file_search,
             enhanced_keys_supported,
             transcript_cells: Vec::new(),
+            transcript_scroll: TranscriptScroll::ToBottom,
+            transcript_selection: TranscriptSelection::default(),
+            transcript_view_top: 0,
+            transcript_total_lines: 0,
             overlay: None,
             deferred_history_lines: Vec::new(),
             has_emitted_history_lines: false,
@@ -493,11 +558,25 @@ impl App {
                 app.handle_tui_event(tui, event).await?
             }
         } {}
+        let width = tui.terminal.last_known_screen_size.width;
+        let session_lines = if width == 0 {
+            Vec::new()
+        } else {
+            let (lines, meta) = Self::build_transcript_lines(&app.transcript_cells, width);
+            let is_user_cell: Vec<bool> = app
+                .transcript_cells
+                .iter()
+                .map(|cell| cell.as_any().is::<UserHistoryCell>())
+                .collect();
+            Self::render_lines_to_ansi(&lines, &meta, &is_user_cell, width)
+        };
+
         tui.terminal.clear()?;
         Ok(AppExitInfo {
             token_usage: app.token_usage(),
             conversation_id: app.chat_widget.conversation_id(),
             update_action: app.pending_update_action,
+            session_lines,
         })
     }
 
@@ -513,6 +592,9 @@ impl App {
                 TuiEvent::Key(key_event) => {
                     self.handle_key_event(tui, key_event).await;
                 }
+                TuiEvent::Mouse(mouse_event) => {
+                    self.handle_mouse_event(tui, mouse_event);
+                }
                 TuiEvent::Paste(pasted) => {
                     // Many terminals convert newlines to \r when pasting (e.g., iTerm2),
                     // but tui-textarea expects \n. Normalize CR to LF.
@@ -529,21 +611,880 @@ impl App {
                     {
                         return Ok(true);
                     }
-                    tui.draw(
-                        self.chat_widget.desired_height(tui.terminal.size()?.width),
-                        |frame| {
-                            self.chat_widget.render(frame.area(), frame.buffer);
-                            if let Some((x, y)) = self.chat_widget.cursor_pos(frame.area()) {
-                                frame.set_cursor_position((x, y));
-                            }
-                        },
-                    )?;
+                    let cells = self.transcript_cells.clone();
+                    tui.draw(tui.terminal.size()?.height, |frame| {
+                        let chat_height = self.chat_widget.desired_height(frame.area().width);
+                        let chat_top = self.render_transcript_cells(frame, &cells, chat_height);
+                        let chat_area = Rect {
+                            x: frame.area().x,
+                            y: chat_top,
+                            width: frame.area().width,
+                            height: chat_height.min(
+                                frame
+                                    .area()
+                                    .height
+                                    .saturating_sub(chat_top.saturating_sub(frame.area().y)),
+                            ),
+                        };
+                        self.chat_widget.render(chat_area, frame.buffer);
+                        let chat_bottom = chat_area.y.saturating_add(chat_area.height);
+                        if chat_bottom < frame.area().bottom() {
+                            Clear.render_ref(
+                                Rect {
+                                    x: frame.area().x,
+                                    y: chat_bottom,
+                                    width: frame.area().width,
+                                    height: frame.area().bottom().saturating_sub(chat_bottom),
+                                },
+                                frame.buffer,
+                            );
+                        }
+                        if let Some((x, y)) = self.chat_widget.cursor_pos(chat_area) {
+                            frame.set_cursor_position((x, y));
+                        }
+                    })?;
+                    let transcript_scrolled =
+                        !matches!(self.transcript_scroll, TranscriptScroll::ToBottom);
+                    let selection_active = matches!(
+                        (self.transcript_selection.anchor, self.transcript_selection.head),
+                        (Some(a), Some(b)) if a != b
+                    );
+                    let scroll_position = if self.transcript_total_lines == 0 {
+                        None
+                    } else {
+                        Some((
+                            self.transcript_view_top.saturating_add(1),
+                            self.transcript_total_lines,
+                        ))
+                    };
+                    self.chat_widget.set_transcript_ui_state(
+                        transcript_scrolled,
+                        selection_active,
+                        scroll_position,
+                    );
                 }
             }
         }
         Ok(true)
     }
 
+    pub(crate) fn render_transcript_cells(
+        &mut self,
+        frame: &mut Frame,
+        cells: &[Arc<dyn HistoryCell>],
+        chat_height: u16,
+    ) -> u16 {
+        let area = frame.area();
+        if area.width == 0 || area.height == 0 {
+            self.transcript_scroll = TranscriptScroll::ToBottom;
+            self.transcript_view_top = 0;
+            self.transcript_total_lines = 0;
+            return area.bottom().saturating_sub(chat_height);
+        }
+
+        let chat_height = chat_height.min(area.height);
+        let max_transcript_height = area.height.saturating_sub(chat_height);
+        if max_transcript_height == 0 {
+            self.transcript_scroll = TranscriptScroll::ToBottom;
+            self.transcript_view_top = 0;
+            self.transcript_total_lines = 0;
+            return area.y;
+        }
+
+        let transcript_area = Rect {
+            x: area.x,
+            y: area.y,
+            width: area.width,
+            height: max_transcript_height,
+        };
+
+        let (lines, meta) = Self::build_transcript_lines(cells, transcript_area.width);
+        if lines.is_empty() {
+            Clear.render_ref(transcript_area, frame.buffer);
+            self.transcript_scroll = TranscriptScroll::ToBottom;
+            self.transcript_view_top = 0;
+            self.transcript_total_lines = 0;
+            return area.y;
+        }
+
+        let wrapped = word_wrap_lines_borrowed(&lines, transcript_area.width.max(1) as usize);
+        if wrapped.is_empty() {
+            self.transcript_scroll = TranscriptScroll::ToBottom;
+            self.transcript_view_top = 0;
+            self.transcript_total_lines = 0;
+            return area.y;
+        }
+
+        let is_user_cell: Vec<bool> = cells
+            .iter()
+            .map(|c| c.as_any().is::<UserHistoryCell>())
+            .collect();
+        let base_opts: RtOptions<'_> = RtOptions::new(transcript_area.width.max(1) as usize);
+        let mut wrapped_is_user_row: Vec<bool> = Vec::with_capacity(wrapped.len());
+        let mut first = true;
+        for (idx, line) in lines.iter().enumerate() {
+            let opts = if first {
+                base_opts.clone()
+            } else {
+                base_opts
+                    .clone()
+                    .initial_indent(base_opts.subsequent_indent.clone())
+            };
+            let seg_count = word_wrap_line(line, opts).len();
+            let is_user_row = meta
+                .get(idx)
+                .and_then(Option::as_ref)
+                .map(|(cell_index, _)| is_user_cell.get(*cell_index).copied().unwrap_or(false))
+                .unwrap_or(false);
+            wrapped_is_user_row.extend(std::iter::repeat_n(is_user_row, seg_count));
+            first = false;
+        }
+
+        let total_lines = wrapped.len();
+        self.transcript_total_lines = total_lines;
+        let max_visible = std::cmp::min(max_transcript_height as usize, total_lines);
+        let max_start = total_lines.saturating_sub(max_visible);
+
+        let top_offset = match self.transcript_scroll {
+            TranscriptScroll::ToBottom => max_start,
+            TranscriptScroll::Scrolled {
+                cell_index,
+                line_in_cell,
+            } => {
+                let mut anchor = None;
+                for (idx, entry) in meta.iter().enumerate() {
+                    if let Some((ci, li)) = entry
+                        && *ci == cell_index
+                        && *li == line_in_cell
+                    {
+                        anchor = Some(idx);
+                        break;
+                    }
+                }
+                if let Some(idx) = anchor {
+                    idx.min(max_start)
+                } else {
+                    self.transcript_scroll = TranscriptScroll::ToBottom;
+                    max_start
+                }
+            }
+        };
+        self.transcript_view_top = top_offset;
+
+        let transcript_visible_height = max_visible as u16;
+        let chat_top = if total_lines <= max_transcript_height as usize {
+            let gap = if transcript_visible_height == 0 { 0 } else { 1 };
+            area.y
+                .saturating_add(transcript_visible_height)
+                .saturating_add(gap)
+        } else {
+            area.bottom().saturating_sub(chat_height)
+        };
+
+        let clear_height = chat_top.saturating_sub(area.y);
+        if clear_height > 0 {
+            Clear.render_ref(
+                Rect {
+                    x: area.x,
+                    y: area.y,
+                    width: area.width,
+                    height: clear_height,
+                },
+                frame.buffer,
+            );
+        }
+
+        let transcript_area = Rect {
+            x: area.x,
+            y: area.y,
+            width: area.width,
+            height: transcript_visible_height,
+        };
+
+        for (row_index, line_index) in (top_offset..total_lines).enumerate() {
+            if row_index >= max_visible {
+                break;
+            }
+
+            let y = transcript_area.y + row_index as u16;
+            let row_area = Rect {
+                x: transcript_area.x,
+                y,
+                width: transcript_area.width,
+                height: 1,
+            };
+
+            if wrapped_is_user_row
+                .get(line_index)
+                .copied()
+                .unwrap_or(false)
+            {
+                let base_style = crate::style::user_message_style();
+                for x in row_area.x..row_area.right() {
+                    let cell = &mut frame.buffer[(x, y)];
+                    let style = cell.style().patch(base_style);
+                    cell.set_style(style);
+                }
+            }
+
+            wrapped[line_index].render_ref(row_area, frame.buffer);
+        }
+
+        self.apply_transcript_selection(transcript_area, frame.buffer);
+        chat_top
+    }
+
+    /// Handle mouse interaction in the main transcript view.
+    ///
+    /// - Mouse wheel movement scrolls the conversation history by small, fixed increments,
+    ///   independent of the terminal's own scrollback.
+    /// - Mouse clicks and drags adjust a text selection defined in terms of
+    ///   flattened transcript lines and columns, so the selection is anchored
+    ///   to the underlying content rather than absolute screen rows.
+    /// - When the user drags to extend a selection while the view is following the bottom
+    ///   and a task is actively running (e.g., streaming a response), the scroll mode is
+    ///   first converted into an anchored position so that ongoing updates no longer move
+    ///   the viewport under the selection. A simple click without a drag does not change
+    ///   scroll behavior.
+    fn handle_mouse_event(
+        &mut self,
+        tui: &mut tui::Tui,
+        mouse_event: crossterm::event::MouseEvent,
+    ) {
+        use crossterm::event::MouseEventKind;
+
+        if self.overlay.is_some() {
+            return;
+        }
+
+        let size = tui.terminal.last_known_screen_size;
+        let width = size.width;
+        let height = size.height;
+        if width == 0 || height == 0 {
+            return;
+        }
+
+        let chat_height = self.chat_widget.desired_height(width);
+        if chat_height >= height {
+            return;
+        }
+
+        // Only handle events over the transcript area above the composer.
+        let transcript_height = height.saturating_sub(chat_height);
+        if transcript_height == 0 {
+            return;
+        }
+
+        let transcript_area = Rect {
+            x: 0,
+            y: 0,
+            width,
+            height: transcript_height,
+        };
+        let base_x = transcript_area.x.saturating_add(2);
+        let max_x = transcript_area.right().saturating_sub(1);
+
+        let mut clamped_x = mouse_event.column;
+        let mut clamped_y = mouse_event.row;
+
+        if clamped_y < transcript_area.y || clamped_y >= transcript_area.bottom() {
+            clamped_y = transcript_area.y;
+        }
+        if clamped_x < base_x {
+            clamped_x = base_x;
+        }
+        if clamped_x > max_x {
+            clamped_x = max_x;
+        }
+
+        let streaming = self.chat_widget.is_task_running();
+
+        match mouse_event.kind {
+            MouseEventKind::ScrollUp => {
+                self.scroll_transcript(
+                    tui,
+                    -3,
+                    transcript_area.height as usize,
+                    transcript_area.width,
+                );
+            }
+            MouseEventKind::ScrollDown => {
+                self.scroll_transcript(
+                    tui,
+                    3,
+                    transcript_area.height as usize,
+                    transcript_area.width,
+                );
+            }
+            MouseEventKind::Down(MouseButton::Left) => {
+                if let Some(point) = self.transcript_point_from_coordinates(
+                    transcript_area,
+                    base_x,
+                    clamped_x,
+                    clamped_y,
+                ) {
+                    self.transcript_selection.anchor = Some(point);
+                    self.transcript_selection.head = Some(point);
+                }
+            }
+            MouseEventKind::Drag(MouseButton::Left) => {
+                if let Some(anchor) = self.transcript_selection.anchor
+                    && let Some(point) = self.transcript_point_from_coordinates(
+                        transcript_area,
+                        base_x,
+                        clamped_x,
+                        clamped_y,
+                    )
+                {
+                    if streaming
+                        && matches!(self.transcript_scroll, TranscriptScroll::ToBottom)
+                        && point != anchor
+                    {
+                        self.lock_transcript_scroll_to_current_view(
+                            transcript_area.height as usize,
+                            transcript_area.width,
+                        );
+                    }
+                    self.transcript_selection.head = Some(point);
+                }
+            }
+            MouseEventKind::Up(MouseButton::Left) => {
+                if self.transcript_selection.anchor == self.transcript_selection.head {
+                    self.transcript_selection = TranscriptSelection::default();
+                }
+            }
+            _ => {}
+        }
+    }
+
+    /// Scroll the transcript by a fixed number of visual lines.
+    ///
+    /// This is the shared implementation behind mouse wheel movement and PgUp/PgDn keys in
+    /// the main view. Scroll state is expressed in terms of transcript cells and their
+    /// internal line indices, so scrolling refers to logical conversation content and
+    /// remains stable even as wrapping or streaming causes visual reflows.
+    fn scroll_transcript(
+        &mut self,
+        tui: &mut tui::Tui,
+        delta_lines: i32,
+        visible_lines: usize,
+        width: u16,
+    ) {
+        if visible_lines == 0 {
+            return;
+        }
+
+        let (lines, meta) = Self::build_transcript_lines(&self.transcript_cells, width);
+        let total_lines = lines.len();
+        if total_lines <= visible_lines {
+            self.transcript_scroll = TranscriptScroll::ToBottom;
+            return;
+        }
+
+        let max_start = total_lines.saturating_sub(visible_lines);
+
+        let current_top = match self.transcript_scroll {
+            TranscriptScroll::ToBottom => max_start,
+            TranscriptScroll::Scrolled {
+                cell_index,
+                line_in_cell,
+            } => {
+                let mut anchor = None;
+                for (idx, entry) in meta.iter().enumerate() {
+                    if let Some((ci, li)) = entry
+                        && *ci == cell_index
+                        && *li == line_in_cell
+                    {
+                        anchor = Some(idx);
+                        break;
+                    }
+                }
+                anchor.unwrap_or(max_start).min(max_start)
+            }
+        };
+
+        if delta_lines == 0 {
+            return;
+        }
+
+        let new_top = if delta_lines < 0 {
+            current_top.saturating_sub(delta_lines.unsigned_abs() as usize)
+        } else {
+            current_top
+                .saturating_add(delta_lines as usize)
+                .min(max_start)
+        };
+
+        if new_top == max_start {
+            self.transcript_scroll = TranscriptScroll::ToBottom;
+        } else {
+            let anchor = meta.iter().skip(new_top).find_map(|entry| *entry);
+            if let Some((cell_index, line_in_cell)) = anchor {
+                self.transcript_scroll = TranscriptScroll::Scrolled {
+                    cell_index,
+                    line_in_cell,
+                };
+            } else if let Some(prev_idx) = (0..=new_top).rfind(|&idx| meta[idx].is_some()) {
+                if let Some((cell_index, line_in_cell)) = meta[prev_idx] {
+                    self.transcript_scroll = TranscriptScroll::Scrolled {
+                        cell_index,
+                        line_in_cell,
+                    };
+                } else {
+                    self.transcript_scroll = TranscriptScroll::ToBottom;
+                }
+            } else {
+                self.transcript_scroll = TranscriptScroll::ToBottom;
+            }
+        }
+
+        tui.frame_requester().schedule_frame();
+    }
+
+    /// Convert a `ToBottom` (auto-follow) scroll state into a fixed anchor at the current view.
+    ///
+    /// When the user begins a mouse selection while new output is streaming in, the view
+    /// should stop auto-following the latest line so the selection stays on the intended
+    /// content. This helper inspects the flattened transcript at the given width, derives
+    /// a concrete position corresponding to the current top row, and switches into a scroll
+    /// mode that keeps that position stable until the user scrolls again.
+    fn lock_transcript_scroll_to_current_view(&mut self, visible_lines: usize, width: u16) {
+        if self.transcript_cells.is_empty() || visible_lines == 0 || width == 0 {
+            return;
+        }
+
+        let (lines, meta) = Self::build_transcript_lines(&self.transcript_cells, width);
+        if lines.is_empty() || meta.is_empty() {
+            return;
+        }
+
+        let total_lines = lines.len();
+        let max_visible = std::cmp::min(visible_lines, total_lines);
+        if max_visible == 0 {
+            return;
+        }
+
+        let max_start = total_lines.saturating_sub(max_visible);
+        let top_offset = match self.transcript_scroll {
+            TranscriptScroll::ToBottom => max_start,
+            TranscriptScroll::Scrolled { .. } => {
+                // Already anchored; nothing to lock.
+                return;
+            }
+        };
+
+        let mut anchor = None;
+        if let Some((cell_index, line_in_cell)) = meta.iter().skip(top_offset).flatten().next() {
+            anchor = Some((*cell_index, *line_in_cell));
+        }
+        if anchor.is_none()
+            && let Some((cell_index, line_in_cell)) =
+                meta[..top_offset].iter().rev().flatten().next()
+        {
+            anchor = Some((*cell_index, *line_in_cell));
+        }
+
+        if let Some((cell_index, line_in_cell)) = anchor {
+            self.transcript_scroll = TranscriptScroll::Scrolled {
+                cell_index,
+                line_in_cell,
+            };
+        }
+    }
+
+    /// Build the flattened transcript lines for rendering, scrolling, and exit transcripts.
+    ///
+    /// Returns both the visible `Line` buffer and a parallel metadata vector
+    /// that maps each line back to its originating `(cell_index, line_in_cell)`
+    /// pair, or `None` for spacer lines. This allows the scroll state to anchor
+    /// to a specific history cell even as new content arrives or the viewport
+    /// size changes, and gives exit transcript renderers enough structure to
+    /// style user rows differently from agent rows.
+    fn build_transcript_lines(
+        cells: &[Arc<dyn HistoryCell>],
+        width: u16,
+    ) -> (Vec<Line<'static>>, Vec<Option<(usize, usize)>>) {
+        let mut lines: Vec<Line<'static>> = Vec::new();
+        let mut meta: Vec<Option<(usize, usize)>> = Vec::new();
+        let mut has_emitted_lines = false;
+
+        for (cell_index, cell) in cells.iter().enumerate() {
+            let cell_lines = cell.display_lines(width);
+            if cell_lines.is_empty() {
+                continue;
+            }
+
+            if !cell.is_stream_continuation() {
+                if has_emitted_lines {
+                    lines.push(Line::from(""));
+                    meta.push(None);
+                } else {
+                    has_emitted_lines = true;
+                }
+            }
+
+            for (line_in_cell, line) in cell_lines.into_iter().enumerate() {
+                meta.push(Some((cell_index, line_in_cell)));
+                lines.push(line);
+            }
+        }
+
+        (lines, meta)
+    }
+
+    /// Render flattened transcript lines into ANSI strings suitable for
+    /// printing after the TUI exits.
+    ///
+    /// This helper mirrors the original TUI viewport behavior:
+    ///  - Merges line-level style into each span so the ANSI output matches
+    ///    the on-screen styling (e.g., blockquotes, lists).
+    ///  - For user-authored rows, pads the background style out to the full
+    ///    terminal width so prompts appear as solid blocks in scrollback.
+    ///  - Streams spans through the shared vt100 writer so downstream tests
+    ///    and tools see consistent escape sequences.
+    fn render_lines_to_ansi(
+        lines: &[Line<'static>],
+        meta: &[Option<(usize, usize)>],
+        is_user_cell: &[bool],
+        width: u16,
+    ) -> Vec<String> {
+        lines
+            .iter()
+            .enumerate()
+            .map(|(idx, line)| {
+                let is_user_row = meta
+                    .get(idx)
+                    .and_then(|entry| entry.as_ref())
+                    .map(|(cell_index, _)| is_user_cell.get(*cell_index).copied().unwrap_or(false))
+                    .unwrap_or(false);
+
+                let mut merged_spans: Vec<ratatui::text::Span<'static>> = line
+                    .spans
+                    .iter()
+                    .map(|span| ratatui::text::Span {
+                        style: span.style.patch(line.style),
+                        content: span.content.clone(),
+                    })
+                    .collect();
+
+                if is_user_row && width > 0 {
+                    let text: String = merged_spans
+                        .iter()
+                        .map(|span| span.content.as_ref())
+                        .collect();
+                    let text_width = UnicodeWidthStr::width(text.as_str());
+                    let total_width = usize::from(width);
+                    if text_width < total_width {
+                        let pad_len = total_width.saturating_sub(text_width);
+                        if pad_len > 0 {
+                            let pad_style = crate::style::user_message_style();
+                            merged_spans.push(ratatui::text::Span {
+                                style: pad_style,
+                                content: " ".repeat(pad_len).into(),
+                            });
+                        }
+                    }
+                }
+
+                let mut buf: Vec<u8> = Vec::new();
+                let _ = crate::insert_history::write_spans(&mut buf, merged_spans.iter());
+                String::from_utf8(buf).unwrap_or_default()
+            })
+            .collect()
+    }
+
+    /// Apply the current transcript selection to the given buffer.
+    ///
+    /// The selection is defined in terms of flattened wrapped transcript line
+    /// indices and columns. This method maps those content-relative endpoints
+    /// into the currently visible viewport based on `transcript_view_top` and
+    /// `transcript_total_lines`, so the highlight moves with the content as the
+    /// user scrolls.
+    fn apply_transcript_selection(&self, area: Rect, buf: &mut Buffer) {
+        let (anchor, head) = match (
+            self.transcript_selection.anchor,
+            self.transcript_selection.head,
+        ) {
+            (Some(a), Some(h)) => (a, h),
+            _ => return,
+        };
+
+        if self.transcript_total_lines == 0 {
+            return;
+        }
+
+        let base_x = area.x.saturating_add(2);
+        let max_x = area.right().saturating_sub(1);
+
+        let mut start = anchor;
+        let mut end = head;
+        if (end.line_index < start.line_index)
+            || (end.line_index == start.line_index && end.column < start.column)
+        {
+            std::mem::swap(&mut start, &mut end);
+        }
+
+        let visible_start = self.transcript_view_top;
+        let visible_end = self
+            .transcript_view_top
+            .saturating_add(area.height as usize)
+            .min(self.transcript_total_lines);
+
+        for (row_index, line_index) in (visible_start..visible_end).enumerate() {
+            if line_index < start.line_index || line_index > end.line_index {
+                continue;
+            }
+
+            let y = area.y + row_index as u16;
+
+            let mut first_text_x = None;
+            let mut last_text_x = None;
+            for x in base_x..=max_x {
+                let cell = &buf[(x, y)];
+                if cell.symbol() != " " {
+                    if first_text_x.is_none() {
+                        first_text_x = Some(x);
+                    }
+                    last_text_x = Some(x);
+                }
+            }
+
+            let (text_start, text_end) = match (first_text_x, last_text_x) {
+                // Treat indentation spaces as part of the selectable region by
+                // starting from the first content column to the right of the
+                // transcript gutter, but still clamp to the last non-space
+                // glyph so trailing padding is not included.
+                (Some(_), Some(e)) => (base_x, e),
+                _ => continue,
+            };
+
+            let line_start_col = if line_index == start.line_index {
+                start.column
+            } else {
+                0
+            };
+            let line_end_col = if line_index == end.line_index {
+                end.column
+            } else {
+                max_x.saturating_sub(base_x)
+            };
+
+            let row_sel_start = base_x.saturating_add(line_start_col);
+            let row_sel_end = base_x.saturating_add(line_end_col).min(max_x);
+
+            if row_sel_start > row_sel_end {
+                continue;
+            }
+
+            let from_x = row_sel_start.max(text_start);
+            let to_x = row_sel_end.min(text_end);
+
+            if from_x > to_x {
+                continue;
+            }
+
+            for x in from_x..=to_x {
+                let cell = &mut buf[(x, y)];
+                let style = cell.style();
+                cell.set_style(style.add_modifier(ratatui::style::Modifier::REVERSED));
+            }
+        }
+    }
+
+    /// Copy the currently selected transcript region to the system clipboard.
+    ///
+    /// The selection is defined in terms of flattened wrapped transcript line
+    /// indices and columns, and this method reconstructs the same wrapped
+    /// transcript used for on-screen rendering so the copied text closely
+    /// matches the highlighted region.
+    fn copy_transcript_selection(&mut self, tui: &tui::Tui) {
+        let (anchor, head) = match (
+            self.transcript_selection.anchor,
+            self.transcript_selection.head,
+        ) {
+            (Some(a), Some(h)) if a != h => (a, h),
+            _ => return,
+        };
+
+        let size = tui.terminal.last_known_screen_size;
+        let width = size.width;
+        let height = size.height;
+        if width == 0 || height == 0 {
+            return;
+        }
+
+        let chat_height = self.chat_widget.desired_height(width);
+        if chat_height >= height {
+            return;
+        }
+
+        let transcript_height = height.saturating_sub(chat_height);
+        if transcript_height == 0 {
+            return;
+        }
+
+        let transcript_area = Rect {
+            x: 0,
+            y: 0,
+            width,
+            height: transcript_height,
+        };
+
+        let cells = self.transcript_cells.clone();
+        let (lines, _) = Self::build_transcript_lines(&cells, transcript_area.width);
+        if lines.is_empty() {
+            return;
+        }
+
+        let wrapped = crate::wrapping::word_wrap_lines_borrowed(
+            &lines,
+            transcript_area.width.max(1) as usize,
+        );
+        let total_lines = wrapped.len();
+        if total_lines == 0 {
+            return;
+        }
+
+        let max_visible = transcript_area.height as usize;
+        let visible_start = self
+            .transcript_view_top
+            .min(total_lines.saturating_sub(max_visible));
+        let visible_end = std::cmp::min(visible_start + max_visible, total_lines);
+
+        let mut buf = Buffer::empty(transcript_area);
+        Clear.render_ref(transcript_area, &mut buf);
+
+        for (row_index, line_index) in (visible_start..visible_end).enumerate() {
+            let row_area = Rect {
+                x: transcript_area.x,
+                y: transcript_area.y + row_index as u16,
+                width: transcript_area.width,
+                height: 1,
+            };
+            wrapped[line_index].render_ref(row_area, &mut buf);
+        }
+
+        let base_x = transcript_area.x.saturating_add(2);
+        let max_x = transcript_area.right().saturating_sub(1);
+
+        let mut start = anchor;
+        let mut end = head;
+        if (end.line_index < start.line_index)
+            || (end.line_index == start.line_index && end.column < start.column)
+        {
+            std::mem::swap(&mut start, &mut end);
+        }
+
+        let mut lines_out: Vec<String> = Vec::new();
+
+        for (row_index, line_index) in (visible_start..visible_end).enumerate() {
+            if line_index < start.line_index || line_index > end.line_index {
+                continue;
+            }
+
+            let y = transcript_area.y + row_index as u16;
+
+            let line_start_col = if line_index == start.line_index {
+                start.column
+            } else {
+                0
+            };
+            let line_end_col = if line_index == end.line_index {
+                end.column
+            } else {
+                max_x.saturating_sub(base_x)
+            };
+
+            let row_sel_start = base_x.saturating_add(line_start_col);
+            let row_sel_end = base_x.saturating_add(line_end_col).min(max_x);
+
+            if row_sel_start > row_sel_end {
+                continue;
+            }
+
+            let mut first_text_x = None;
+            let mut last_text_x = None;
+            for x in base_x..=max_x {
+                let cell = &buf[(x, y)];
+                if cell.symbol() != " " {
+                    if first_text_x.is_none() {
+                        first_text_x = Some(x);
+                    }
+                    last_text_x = Some(x);
+                }
+            }
+
+            let (text_start, text_end) = match (first_text_x, last_text_x) {
+                // Treat indentation spaces as part of the copyable region by
+                // starting from the first content column to the right of the
+                // transcript gutter, but still clamp to the last non-space
+                // glyph so trailing padding is not included.
+                (Some(_), Some(e)) => (base_x, e),
+                _ => {
+                    lines_out.push(String::new());
+                    continue;
+                }
+            };
+
+            let from_x = row_sel_start.max(text_start);
+            let to_x = row_sel_end.min(text_end);
+            if from_x > to_x {
+                continue;
+            }
+
+            let mut line_text = String::new();
+            for x in from_x..=to_x {
+                let cell = &buf[(x, y)];
+                let symbol = cell.symbol();
+                if !symbol.is_empty() {
+                    line_text.push_str(symbol);
+                }
+            }
+
+            lines_out.push(line_text);
+        }
+
+        if lines_out.is_empty() {
+            return;
+        }
+
+        let text = lines_out.join("\n");
+        if let Err(err) = clipboard_copy::copy_text(text) {
+            tracing::error!(error = %err, "failed to copy selection to clipboard");
+        }
+    }
+
+    /// Map a mouse position in the transcript area to a content-relative
+    /// selection point, if there is transcript content to select.
+    fn transcript_point_from_coordinates(
+        &self,
+        transcript_area: Rect,
+        base_x: u16,
+        x: u16,
+        y: u16,
+    ) -> Option<TranscriptSelectionPoint> {
+        if self.transcript_total_lines == 0 {
+            return None;
+        }
+
+        let mut row_index = y.saturating_sub(transcript_area.y);
+        if row_index >= transcript_area.height {
+            if transcript_area.height == 0 {
+                return None;
+            }
+            row_index = transcript_area.height.saturating_sub(1);
+        }
+
+        let max_line = self.transcript_total_lines.saturating_sub(1);
+        let line_index = self
+            .transcript_view_top
+            .saturating_add(usize::from(row_index))
+            .min(max_line);
+        let column = x.saturating_sub(base_x);
+
+        Some(TranscriptSelectionPoint { line_index, column })
+    }
+
     async fn handle_event(&mut self, tui: &mut tui::Tui, event: AppEvent) -> Result<bool> {
         let model_family = self
             .server
@@ -655,8 +1596,8 @@ impl App {
             }
             AppEvent::InsertHistoryCell(cell) => {
                 let cell: Arc<dyn HistoryCell> = cell.into();
-                if let Some(Overlay::Transcript(t)) = &mut self.overlay {
-                    t.insert_cell(cell.clone());
+                if let Some(Overlay::Transcript(transcript)) = &mut self.overlay {
+                    transcript.insert_cell(cell.clone());
                     tui.frame_requester().schedule_frame();
                 }
                 self.transcript_cells.push(cell.clone());
@@ -674,8 +1615,6 @@ impl App {
                     }
                     if self.overlay.is_some() {
                         self.deferred_history_lines.extend(display);
-                    } else {
-                        tui.insert_history_lines(display);
                     }
                 }
             }
@@ -1139,6 +2078,83 @@ impl App {
                     self.chat_widget.handle_key_event(key_event);
                 }
             }
+            KeyEvent {
+                code: KeyCode::Char('y'),
+                modifiers: crossterm::event::KeyModifiers::CONTROL,
+                kind: KeyEventKind::Press | KeyEventKind::Repeat,
+                ..
+            } => {
+                self.copy_transcript_selection(tui);
+            }
+            KeyEvent {
+                code: KeyCode::PageUp,
+                kind: KeyEventKind::Press | KeyEventKind::Repeat,
+                ..
+            } => {
+                let size = tui.terminal.last_known_screen_size;
+                let width = size.width;
+                let height = size.height;
+                if width > 0 && height > 0 {
+                    let chat_height = self.chat_widget.desired_height(width);
+                    if chat_height < height {
+                        let transcript_height = height.saturating_sub(chat_height);
+                        if transcript_height > 0 {
+                            let delta = -i32::from(transcript_height);
+                            self.scroll_transcript(
+                                tui,
+                                delta,
+                                usize::from(transcript_height),
+                                width,
+                            );
+                        }
+                    }
+                }
+            }
+            KeyEvent {
+                code: KeyCode::PageDown,
+                kind: KeyEventKind::Press | KeyEventKind::Repeat,
+                ..
+            } => {
+                let size = tui.terminal.last_known_screen_size;
+                let width = size.width;
+                let height = size.height;
+                if width > 0 && height > 0 {
+                    let chat_height = self.chat_widget.desired_height(width);
+                    if chat_height < height {
+                        let transcript_height = height.saturating_sub(chat_height);
+                        if transcript_height > 0 {
+                            let delta = i32::from(transcript_height);
+                            self.scroll_transcript(
+                                tui,
+                                delta,
+                                usize::from(transcript_height),
+                                width,
+                            );
+                        }
+                    }
+                }
+            }
+            KeyEvent {
+                code: KeyCode::Home,
+                kind: KeyEventKind::Press | KeyEventKind::Repeat,
+                ..
+            } => {
+                if !self.transcript_cells.is_empty() {
+                    self.transcript_scroll = TranscriptScroll::Scrolled {
+                        cell_index: 0,
+                        line_in_cell: 0,
+                    };
+                    tui.frame_requester().schedule_frame();
+                }
+            }
+            KeyEvent {
+                code: KeyCode::End,
+                kind: KeyEventKind::Press | KeyEventKind::Repeat,
+                ..
+            } => {
+                self.transcript_scroll = TranscriptScroll::ToBottom;
+                tui.frame_requester().schedule_frame();
+            }
             // Enter confirms backtrack when primed + count > 0. Otherwise pass to widget.
             KeyEvent {
                 code: KeyCode::Enter,
@@ -1218,6 +2234,7 @@ mod tests {
     use codex_core::protocol::SandboxPolicy;
     use codex_core::protocol::SessionConfiguredEvent;
     use codex_protocol::ConversationId;
+    use pretty_assertions::assert_eq;
     use ratatui::prelude::Line;
     use std::path::PathBuf;
     use std::sync::Arc;
@@ -1245,6 +2262,10 @@ mod tests {
             active_profile: None,
             file_search,
             transcript_cells: Vec::new(),
+            transcript_scroll: TranscriptScroll::ToBottom,
+            transcript_selection: TranscriptSelection::default(),
+            transcript_view_top: 0,
+            transcript_total_lines: 0,
             overlay: None,
             deferred_history_lines: Vec::new(),
             has_emitted_history_lines: false,
@@ -1285,6 +2306,10 @@ mod tests {
                 active_profile: None,
                 file_search,
                 transcript_cells: Vec::new(),
+                transcript_scroll: TranscriptScroll::ToBottom,
+                transcript_selection: TranscriptSelection::default(),
+                transcript_view_top: 0,
+                transcript_total_lines: 0,
                 overlay: None,
                 deferred_history_lines: Vec::new(),
                 has_emitted_history_lines: false,
@@ -1444,6 +2469,68 @@ mod tests {
         assert_eq!(prefill, "follow-up (edited)");
     }
 
+    #[test]
+    fn transcript_selection_moves_with_scroll() {
+        use ratatui::buffer::Buffer;
+        use ratatui::layout::Rect;
+
+        let mut app = make_test_app();
+        app.transcript_total_lines = 3;
+
+        let area = Rect {
+            x: 0,
+            y: 0,
+            width: 10,
+            height: 2,
+        };
+
+        // Anchor selection to logical line 1, columns 2..4.
+        app.transcript_selection = TranscriptSelection {
+            anchor: Some(TranscriptSelectionPoint {
+                line_index: 1,
+                column: 2,
+            }),
+            head: Some(TranscriptSelectionPoint {
+                line_index: 1,
+                column: 4,
+            }),
+        };
+
+        // First render: top of view is line 0, so line 1 maps to the second row.
+        app.transcript_view_top = 0;
+        let mut buf = Buffer::empty(area);
+        for x in 2..area.width {
+            buf[(x, 0)].set_symbol("A");
+            buf[(x, 1)].set_symbol("B");
+        }
+
+        app.apply_transcript_selection(area, &mut buf);
+
+        // No selection should be applied to the first row when the view is anchored at the top.
+        for x in 0..area.width {
+            let cell = &buf[(x, 0)];
+            assert!(cell.style().add_modifier.is_empty());
+        }
+
+        // After scrolling down by one line, the same logical line should now be
+        // rendered on the first row, and the highlight should move with it.
+        app.transcript_view_top = 1;
+        let mut buf_scrolled = Buffer::empty(area);
+        for x in 2..area.width {
+            buf_scrolled[(x, 0)].set_symbol("B");
+            buf_scrolled[(x, 1)].set_symbol("C");
+        }
+
+        app.apply_transcript_selection(area, &mut buf_scrolled);
+
+        // After scrolling, the selection should now be applied on the first row rather than the
+        // second.
+        for x in 0..area.width {
+            let cell = &buf_scrolled[(x, 1)];
+            assert!(cell.style().add_modifier.is_empty());
+        }
+    }
+
     #[tokio::test]
     async fn new_session_requests_shutdown_for_previous_conversation() {
         let (mut app, mut app_event_rx, mut op_rx) = make_test_app_with_channels();
@@ -1485,6 +2572,19 @@ mod tests {
         assert!(session_summary(TokenUsage::default(), None).is_none());
     }
 
+    #[test]
+    fn render_lines_to_ansi_pads_user_rows_to_full_width() {
+        let line: Line<'static> = Line::from("hi");
+        let lines = vec![line];
+        let meta = vec![Some((0usize, 0usize))];
+        let is_user_cell = vec![true];
+        let width: u16 = 10;
+
+        let rendered = App::render_lines_to_ansi(&lines, &meta, &is_user_cell, width);
+        assert_eq!(rendered.len(), 1);
+        assert!(rendered[0].contains("hi"));
+    }
+
     #[test]
     fn session_summary_includes_resume_hint() {
         let usage = TokenUsage {
diff --git a/codex-rs/tui2/src/bottom_pane/chat_composer.rs b/codex-rs/tui2/src/bottom_pane/chat_composer.rs
index 919866b00c..7ca10c6d24 100644
--- a/codex-rs/tui2/src/bottom_pane/chat_composer.rs
+++ b/codex-rs/tui2/src/bottom_pane/chat_composer.rs
@@ -118,6 +118,9 @@ pub(crate) struct ChatComposer {
     footer_hint_override: Option<Vec<(String, String)>>,
     context_window_percent: Option<i64>,
     context_window_used_tokens: Option<i64>,
+    transcript_scrolled: bool,
+    transcript_selection_active: bool,
+    transcript_scroll_position: Option<(usize, usize)>,
     skills: Option<Vec<SkillMetadata>>,
     dismissed_skill_popup_token: Option<String>,
 }
@@ -166,6 +169,9 @@ impl ChatComposer {
             footer_hint_override: None,
             context_window_percent: None,
             context_window_used_tokens: None,
+            transcript_scrolled: false,
+            transcript_selection_active: false,
+            transcript_scroll_position: None,
             skills: None,
             dismissed_skill_popup_token: None,
         };
@@ -1531,6 +1537,9 @@ impl ChatComposer {
             is_task_running: self.is_task_running,
             context_window_percent: self.context_window_percent,
             context_window_used_tokens: self.context_window_used_tokens,
+            transcript_scrolled: self.transcript_scrolled,
+            transcript_selection_active: self.transcript_selection_active,
+            transcript_scroll_position: self.transcript_scroll_position,
         }
     }
 
@@ -1551,6 +1560,23 @@ impl ChatComposer {
             .map(|items| if items.is_empty() { 0 } else { 1 })
     }
 
+    /// Update the footer's view of transcript scroll state for the inline viewport.
+    ///
+    /// This state is derived from the main `App`'s transcript viewport and passed
+    /// through the bottom pane so the footer can indicate when the transcript is
+    /// scrolled away from the bottom, whether a selection is active, and the
+    /// current `(visible_top, total)` position.
+    pub(crate) fn set_transcript_ui_state(
+        &mut self,
+        scrolled: bool,
+        selection_active: bool,
+        scroll_position: Option<(usize, usize)>,
+    ) {
+        self.transcript_scrolled = scrolled;
+        self.transcript_selection_active = selection_active;
+        self.transcript_scroll_position = scroll_position;
+    }
+
     fn sync_popups(&mut self) {
         let file_token = Self::current_at_token(&self.textarea);
         let skill_token = self.current_skill_token();
diff --git a/codex-rs/tui2/src/bottom_pane/footer.rs b/codex-rs/tui2/src/bottom_pane/footer.rs
index d47ffec98b..7f2b4e6285 100644
--- a/codex-rs/tui2/src/bottom_pane/footer.rs
+++ b/codex-rs/tui2/src/bottom_pane/footer.rs
@@ -22,6 +22,9 @@ pub(crate) struct FooterProps {
     pub(crate) is_task_running: bool,
     pub(crate) context_window_percent: Option<i64>,
     pub(crate) context_window_used_tokens: Option<i64>,
+    pub(crate) transcript_scrolled: bool,
+    pub(crate) transcript_selection_active: bool,
+    pub(crate) transcript_scroll_position: Option<(usize, usize)>,
 }
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
@@ -94,6 +97,27 @@ fn footer_lines(props: FooterProps) -> Vec<Line<'static>> {
                 key_hint::plain(KeyCode::Char('?')).into(),
                 " for shortcuts".dim(),
             ]);
+            if props.transcript_scrolled {
+                line.push_span(" · ".dim());
+                line.push_span(key_hint::plain(KeyCode::PageUp));
+                line.push_span("/");
+                line.push_span(key_hint::plain(KeyCode::PageDown));
+                line.push_span(" scroll".dim());
+                line.push_span(" · ".dim());
+                line.push_span(key_hint::plain(KeyCode::Home));
+                line.push_span("/");
+                line.push_span(key_hint::plain(KeyCode::End));
+                line.push_span(" jump".dim());
+                if let Some((current, total)) = props.transcript_scroll_position {
+                    line.push_span(" · ".dim());
+                    line.push_span(Span::from(format!("{current}/{total}")).dim());
+                }
+            }
+            if props.transcript_selection_active {
+                line.push_span(" · ".dim());
+                line.push_span(key_hint::ctrl(KeyCode::Char('y')));
+                line.push_span(" copy selection".dim());
+            }
             vec![line]
         }
         FooterMode::ShortcutOverlay => {
@@ -440,6 +464,24 @@ mod tests {
                 is_task_running: false,
                 context_window_percent: None,
                 context_window_used_tokens: None,
+                transcript_scrolled: false,
+                transcript_selection_active: false,
+                transcript_scroll_position: None,
+            },
+        );
+
+        snapshot_footer(
+            "footer_shortcuts_transcript_scrolled_and_selection",
+            FooterProps {
+                mode: FooterMode::ShortcutSummary,
+                esc_backtrack_hint: false,
+                use_shift_enter_hint: false,
+                is_task_running: false,
+                context_window_percent: None,
+                context_window_used_tokens: None,
+                transcript_scrolled: true,
+                transcript_selection_active: true,
+                transcript_scroll_position: Some((3, 42)),
             },
         );
 
@@ -452,6 +494,9 @@ mod tests {
                 is_task_running: false,
                 context_window_percent: None,
                 context_window_used_tokens: None,
+                transcript_scrolled: false,
+                transcript_selection_active: false,
+                transcript_scroll_position: None,
             },
         );
 
@@ -464,6 +509,9 @@ mod tests {
                 is_task_running: false,
                 context_window_percent: None,
                 context_window_used_tokens: None,
+                transcript_scrolled: false,
+                transcript_selection_active: false,
+                transcript_scroll_position: None,
             },
         );
 
@@ -476,6 +524,9 @@ mod tests {
                 is_task_running: true,
                 context_window_percent: None,
                 context_window_used_tokens: None,
+                transcript_scrolled: false,
+                transcript_selection_active: false,
+                transcript_scroll_position: None,
             },
         );
 
@@ -488,6 +539,9 @@ mod tests {
                 is_task_running: false,
                 context_window_percent: None,
                 context_window_used_tokens: None,
+                transcript_scrolled: false,
+                transcript_selection_active: false,
+                transcript_scroll_position: None,
             },
         );
 
@@ -500,6 +554,9 @@ mod tests {
                 is_task_running: false,
                 context_window_percent: None,
                 context_window_used_tokens: None,
+                transcript_scrolled: false,
+                transcript_selection_active: false,
+                transcript_scroll_position: None,
             },
         );
 
@@ -512,6 +569,9 @@ mod tests {
                 is_task_running: true,
                 context_window_percent: Some(72),
                 context_window_used_tokens: None,
+                transcript_scrolled: false,
+                transcript_selection_active: false,
+                transcript_scroll_position: None,
             },
         );
 
@@ -524,6 +584,9 @@ mod tests {
                 is_task_running: false,
                 context_window_percent: None,
                 context_window_used_tokens: Some(123_456),
+                transcript_scrolled: false,
+                transcript_selection_active: false,
+                transcript_scroll_position: None,
             },
         );
     }
diff --git a/codex-rs/tui2/src/bottom_pane/mod.rs b/codex-rs/tui2/src/bottom_pane/mod.rs
index 8516687284..fbab5e14a2 100644
--- a/codex-rs/tui2/src/bottom_pane/mod.rs
+++ b/codex-rs/tui2/src/bottom_pane/mod.rs
@@ -381,6 +381,17 @@ impl BottomPane {
         self.request_redraw();
     }
 
+    pub(crate) fn set_transcript_ui_state(
+        &mut self,
+        scrolled: bool,
+        selection_active: bool,
+        scroll_position: Option<(usize, usize)>,
+    ) {
+        self.composer
+            .set_transcript_ui_state(scrolled, selection_active, scroll_position);
+        self.request_redraw();
+    }
+
     /// Show a generic list selection view with the provided items.
     pub(crate) fn show_selection_view(&mut self, params: list_selection_view::SelectionViewParams) {
         let view = list_selection_view::ListSelectionView::new(params, self.app_event_tx.clone());
diff --git a/codex-rs/tui2/src/bottom_pane/snapshots/codex_tui2__bottom_pane__footer__tests__footer_shortcuts_transcript_scrolled_and_selection.snap b/codex-rs/tui2/src/bottom_pane/snapshots/codex_tui2__bottom_pane__footer__tests__footer_shortcuts_transcript_scrolled_and_selection.snap
new file mode 100644
index 0000000000..ee592efa26
--- /dev/null
+++ b/codex-rs/tui2/src/bottom_pane/snapshots/codex_tui2__bottom_pane__footer__tests__footer_shortcuts_transcript_scrolled_and_selection.snap
@@ -0,0 +1,5 @@
+---
+source: tui2/src/bottom_pane/footer.rs
+expression: terminal.backend()
+---
+"  100% context left · ? for shortcuts · pgup/pgdn scroll · home/end jump · 3/42 "
diff --git a/codex-rs/tui2/src/chatwidget.rs b/codex-rs/tui2/src/chatwidget.rs
index 7dec1ae542..5461bea729 100644
--- a/codex-rs/tui2/src/chatwidget.rs
+++ b/codex-rs/tui2/src/chatwidget.rs
@@ -3073,6 +3073,30 @@ impl ChatWidget {
     pub(crate) fn clear_esc_backtrack_hint(&mut self) {
         self.bottom_pane.clear_esc_backtrack_hint();
     }
+
+    /// Return true when the bottom pane currently has an active task.
+    ///
+    /// This is used by the viewport to decide when mouse selections should
+    /// disengage auto-follow behavior while responses are streaming.
+    pub(crate) fn is_task_running(&self) -> bool {
+        self.bottom_pane.is_task_running()
+    }
+
+    /// Inform the bottom pane about the current transcript scroll state.
+    ///
+    /// This is used by the footer to surface when the inline transcript is
+    /// scrolled away from the bottom and to display the current
+    /// `(visible_top, total)` scroll position alongside other shortcuts.
+    pub(crate) fn set_transcript_ui_state(
+        &mut self,
+        scrolled: bool,
+        selection_active: bool,
+        scroll_position: Option<(usize, usize)>,
+    ) {
+        self.bottom_pane
+            .set_transcript_ui_state(scrolled, selection_active, scroll_position);
+    }
+
     /// Forward an `Op` directly to codex.
     pub(crate) fn submit_op(&self, op: Op) {
         // Record outbound operation for session replay fidelity.
diff --git a/codex-rs/tui2/src/clipboard_copy.rs b/codex-rs/tui2/src/clipboard_copy.rs
new file mode 100644
index 0000000000..76718704e5
--- /dev/null
+++ b/codex-rs/tui2/src/clipboard_copy.rs
@@ -0,0 +1,79 @@
+use tracing::error;
+
+#[derive(Debug)]
+pub enum ClipboardError {
+    ClipboardUnavailable(String),
+    WriteFailed(String),
+}
+
+impl std::fmt::Display for ClipboardError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ClipboardError::ClipboardUnavailable(msg) => {
+                write!(f, "clipboard unavailable: {msg}")
+            }
+            ClipboardError::WriteFailed(msg) => write!(f, "failed to write to clipboard: {msg}"),
+        }
+    }
+}
+
+impl std::error::Error for ClipboardError {}
+
+pub trait ClipboardManager {
+    fn set_text(&mut self, text: String) -> Result<(), ClipboardError>;
+}
+
+#[cfg(not(target_os = "android"))]
+pub struct ArboardClipboardManager {
+    inner: Option<arboard::Clipboard>,
+}
+
+#[cfg(not(target_os = "android"))]
+impl ArboardClipboardManager {
+    pub fn new() -> Self {
+        match arboard::Clipboard::new() {
+            Ok(cb) => Self { inner: Some(cb) },
+            Err(err) => {
+                error!(error = %err, "failed to initialize clipboard");
+                Self { inner: None }
+            }
+        }
+    }
+}
+
+#[cfg(not(target_os = "android"))]
+impl ClipboardManager for ArboardClipboardManager {
+    fn set_text(&mut self, text: String) -> Result<(), ClipboardError> {
+        let Some(cb) = &mut self.inner else {
+            return Err(ClipboardError::ClipboardUnavailable(
+                "clipboard is not available in this environment".to_string(),
+            ));
+        };
+        cb.set_text(text)
+            .map_err(|e| ClipboardError::WriteFailed(e.to_string()))
+    }
+}
+
+#[cfg(target_os = "android")]
+pub struct ArboardClipboardManager;
+
+#[cfg(target_os = "android")]
+impl ArboardClipboardManager {
+    pub fn new() -> Self {
+        ArboardClipboardManager
+    }
+}
+
+#[cfg(target_os = "android")]
+impl ClipboardManager for ArboardClipboardManager {
+    fn set_text(&mut self, _text: String) -> Result<(), ClipboardError> {
+        Err(ClipboardError::ClipboardUnavailable(
+            "clipboard text copy is unsupported on Android".to_string(),
+        ))
+    }
+}
+
+pub fn copy_text(text: String) -> Result<(), ClipboardError> {
+    let mut manager = ArboardClipboardManager::new();
+    manager.set_text(text)
+}
diff --git a/codex-rs/tui2/src/insert_history.rs b/codex-rs/tui2/src/insert_history.rs
index 36ef47da5e..e0e2731678 100644
--- a/codex-rs/tui2/src/insert_history.rs
+++ b/codex-rs/tui2/src/insert_history.rs
@@ -241,7 +241,7 @@ impl ModifierDiff {
     }
 }
 
-fn write_spans<'a, I>(mut writer: &mut impl Write, content: I) -> io::Result<()>
+pub(crate) fn write_spans<'a, I>(mut writer: &mut impl Write, content: I) -> io::Result<()>
 where
     I: IntoIterator<Item = &'a Span<'a>>,
 {
diff --git a/codex-rs/tui2/src/lib.rs b/codex-rs/tui2/src/lib.rs
index a0c034c146..7587779234 100644
--- a/codex-rs/tui2/src/lib.rs
+++ b/codex-rs/tui2/src/lib.rs
@@ -40,6 +40,7 @@ mod ascii_animation;
 mod bottom_pane;
 mod chatwidget;
 mod cli;
+mod clipboard_copy;
 mod clipboard_paste;
 mod color;
 pub mod custom_terminal;
@@ -369,6 +370,7 @@ async fn run_ratatui_app(
                         token_usage: codex_core::protocol::TokenUsage::default(),
                         conversation_id: None,
                         update_action: Some(action),
+                        session_lines: Vec::new(),
                     });
                 }
             }
@@ -408,6 +410,7 @@ async fn run_ratatui_app(
                 token_usage: codex_core::protocol::TokenUsage::default(),
                 conversation_id: None,
                 update_action: None,
+                session_lines: Vec::new(),
             });
         }
         // if the user acknowledged windows or made an explicit decision ato trust the directory, reload the config accordingly
@@ -443,6 +446,7 @@ async fn run_ratatui_app(
                     token_usage: codex_core::protocol::TokenUsage::default(),
                     conversation_id: None,
                     update_action: None,
+                    session_lines: Vec::new(),
                 });
             }
         }
@@ -481,6 +485,7 @@ async fn run_ratatui_app(
                     token_usage: codex_core::protocol::TokenUsage::default(),
                     conversation_id: None,
                     update_action: None,
+                    session_lines: Vec::new(),
                 });
             }
             other => other,
@@ -491,6 +496,12 @@ async fn run_ratatui_app(
 
     let Cli { prompt, images, .. } = cli;
 
+    // Run the main chat + transcript UI on the terminal's alternate screen so
+    // the entire viewport can be used without polluting normal scrollback. This
+    // mirrors the behavior of the legacy TUI but keeps inline mode available
+    // for smaller prompts like onboarding and model migration.
+    let _ = tui.enter_alt_screen();
+
     let app_result = App::run(
         &mut tui,
         auth_manager,
@@ -504,7 +515,17 @@ async fn run_ratatui_app(
     )
     .await;
 
+    let _ = tui.leave_alt_screen();
     restore();
+    if let Ok(exit_info) = &app_result {
+        let mut stdout = std::io::stdout();
+        for line in exit_info.session_lines.iter() {
+            let _ = writeln!(stdout, "{line}");
+        }
+        if !exit_info.session_lines.is_empty() {
+            let _ = writeln!(stdout);
+        }
+    }
     // Mark the end of the recorded session.
     session_log::log_session_end();
     // ignore error when collecting usage – report underlying error instead
diff --git a/codex-rs/tui2/src/model_migration.rs b/codex-rs/tui2/src/model_migration.rs
index fa59b8fcc9..90cd4b2b37 100644
--- a/codex-rs/tui2/src/model_migration.rs
+++ b/codex-rs/tui2/src/model_migration.rs
@@ -114,6 +114,7 @@ pub(crate) async fn run_model_migration_prompt(
         if let Some(event) = events.next().await {
             match event {
                 TuiEvent::Key(key_event) => screen.handle_key(key_event),
+                TuiEvent::Mouse(_) => {}
                 TuiEvent::Paste(_) => {}
                 TuiEvent::Draw => {
                     let _ = alt.tui.draw(u16::MAX, |frame| {
diff --git a/codex-rs/tui2/src/onboarding/onboarding_screen.rs b/codex-rs/tui2/src/onboarding/onboarding_screen.rs
index 14999b2229..3ba2619a87 100644
--- a/codex-rs/tui2/src/onboarding/onboarding_screen.rs
+++ b/codex-rs/tui2/src/onboarding/onboarding_screen.rs
@@ -393,6 +393,7 @@ pub(crate) async fn run_onboarding_app(
     while !onboarding_screen.is_done() {
         if let Some(event) = tui_events.next().await {
             match event {
+                TuiEvent::Mouse(_) => {}
                 TuiEvent::Key(key_event) => {
                     onboarding_screen.handle_key_event(key_event);
                 }
diff --git a/codex-rs/tui2/src/pager_overlay.rs b/codex-rs/tui2/src/pager_overlay.rs
index 46aaba8644..06a7cad467 100644
--- a/codex-rs/tui2/src/pager_overlay.rs
+++ b/codex-rs/tui2/src/pager_overlay.rs
@@ -14,6 +14,8 @@ use crate::tui;
 use crate::tui::TuiEvent;
 use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;
+use crossterm::event::MouseEvent;
+use crossterm::event::MouseEventKind;
 use ratatui::buffer::Buffer;
 use ratatui::buffer::Cell;
 use ratatui::layout::Rect;
@@ -283,6 +285,24 @@ impl PagerView {
         Ok(())
     }
 
+    fn handle_mouse_scroll(&mut self, tui: &mut tui::Tui, event: MouseEvent) -> Result<()> {
+        let step: usize = 3;
+        match event.kind {
+            MouseEventKind::ScrollUp => {
+                self.scroll_offset = self.scroll_offset.saturating_sub(step);
+            }
+            MouseEventKind::ScrollDown => {
+                self.scroll_offset = self.scroll_offset.saturating_add(step);
+            }
+            _ => {
+                return Ok(());
+            }
+        }
+        tui.frame_requester()
+            .schedule_frame_in(Duration::from_millis(16));
+        Ok(())
+    }
+
     /// Returns the height of one page in content rows.
     ///
     /// Prefers the last rendered content height (excluding header/footer chrome);
@@ -506,6 +526,7 @@ impl TranscriptOverlay {
                 }
                 other => self.view.handle_key_event(tui, other),
             },
+            TuiEvent::Mouse(mouse_event) => self.view.handle_mouse_scroll(tui, mouse_event),
             TuiEvent::Draw => {
                 tui.draw(u16::MAX, |frame| {
                     self.render(frame.area(), frame.buffer);
@@ -565,6 +586,7 @@ impl StaticOverlay {
                 }
                 other => self.view.handle_key_event(tui, other),
             },
+            TuiEvent::Mouse(mouse_event) => self.view.handle_mouse_scroll(tui, mouse_event),
             TuiEvent::Draw => {
                 tui.draw(u16::MAX, |frame| {
                     self.render(frame.area(), frame.buffer);
diff --git a/codex-rs/tui2/src/skill_error_prompt.rs b/codex-rs/tui2/src/skill_error_prompt.rs
index 33d3b5dce1..41aaefa4c9 100644
--- a/codex-rs/tui2/src/skill_error_prompt.rs
+++ b/codex-rs/tui2/src/skill_error_prompt.rs
@@ -58,6 +58,7 @@ pub(crate) async fn run_skill_error_prompt(
         if let Some(event) = events.next().await {
             match event {
                 TuiEvent::Key(key_event) => screen.handle_key(key_event),
+                TuiEvent::Mouse(_) => {}
                 TuiEvent::Paste(_) => {}
                 TuiEvent::Draw => {
                     let _ = alt.tui.draw(u16::MAX, |frame| {
diff --git a/codex-rs/tui2/src/tui.rs b/codex-rs/tui2/src/tui.rs
index f9566da908..807c807c87 100644
--- a/codex-rs/tui2/src/tui.rs
+++ b/codex-rs/tui2/src/tui.rs
@@ -1,4 +1,3 @@
-use std::fmt;
 use std::io::IsTerminal;
 use std::io::Result;
 use std::io::Stdout;
@@ -10,12 +9,13 @@ use std::sync::Arc;
 use std::sync::atomic::AtomicBool;
 use std::sync::atomic::Ordering;
 
-use crossterm::Command;
 use crossterm::SynchronizedUpdate;
 use crossterm::event::DisableBracketedPaste;
 use crossterm::event::DisableFocusChange;
+use crossterm::event::DisableMouseCapture;
 use crossterm::event::EnableBracketedPaste;
 use crossterm::event::EnableFocusChange;
+use crossterm::event::EnableMouseCapture;
 use crossterm::event::Event;
 use crossterm::event::KeyEvent;
 use crossterm::event::KeyboardEnhancementFlags;
@@ -24,7 +24,6 @@ use crossterm::event::PushKeyboardEnhancementFlags;
 use crossterm::terminal::EnterAlternateScreen;
 use crossterm::terminal::LeaveAlternateScreen;
 use crossterm::terminal::supports_keyboard_enhancement;
-use ratatui::backend::Backend;
 use ratatui::backend::CrosstermBackend;
 use ratatui::crossterm::execute;
 use ratatui::crossterm::terminal::disable_raw_mode;
@@ -74,56 +73,18 @@ pub fn set_modes() -> Result<()> {
     );
 
     let _ = execute!(stdout(), EnableFocusChange);
+    // Enable application mouse mode so scroll events are delivered as
+    // Mouse events instead of arrow keys.
+    let _ = execute!(stdout(), EnableMouseCapture);
     Ok(())
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-struct EnableAlternateScroll;
-
-impl Command for EnableAlternateScroll {
-    fn write_ansi(&self, f: &mut impl fmt::Write) -> fmt::Result {
-        write!(f, "\x1b[?1007h")
-    }
-
-    #[cfg(windows)]
-    fn execute_winapi(&self) -> Result<()> {
-        Err(std::io::Error::other(
-            "tried to execute EnableAlternateScroll using WinAPI; use ANSI instead",
-        ))
-    }
-
-    #[cfg(windows)]
-    fn is_ansi_code_supported(&self) -> bool {
-        true
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-struct DisableAlternateScroll;
-
-impl Command for DisableAlternateScroll {
-    fn write_ansi(&self, f: &mut impl fmt::Write) -> fmt::Result {
-        write!(f, "\x1b[?1007l")
-    }
-
-    #[cfg(windows)]
-    fn execute_winapi(&self) -> Result<()> {
-        Err(std::io::Error::other(
-            "tried to execute DisableAlternateScroll using WinAPI; use ANSI instead",
-        ))
-    }
-
-    #[cfg(windows)]
-    fn is_ansi_code_supported(&self) -> bool {
-        true
-    }
-}
-
 /// Restore the terminal to its original state.
 /// Inverse of `set_modes`.
 pub fn restore() -> Result<()> {
     // Pop may fail on platforms that didn't support the push; ignore errors.
     let _ = execute!(stdout(), PopKeyboardEnhancementFlags);
+    let _ = execute!(stdout(), DisableMouseCapture);
     execute!(stdout(), DisableBracketedPaste)?;
     let _ = execute!(stdout(), DisableFocusChange);
     disable_raw_mode()?;
@@ -161,6 +122,7 @@ pub enum TuiEvent {
     Key(KeyEvent),
     Paste(String),
     Draw,
+    Mouse(crossterm::event::MouseEvent),
 }
 
 pub struct Tui {
@@ -297,6 +259,9 @@ impl Tui {
                                     Event::Paste(pasted) => {
                                         yield TuiEvent::Paste(pasted);
                                     }
+                                    Event::Mouse(mouse_event) => {
+                                        yield TuiEvent::Mouse(mouse_event);
+                                    }
                                     Event::FocusGained => {
                                         terminal_focused.store(true, Ordering::Relaxed);
                                         crate::terminal_palette::requery_default_colors();
@@ -305,7 +270,6 @@ impl Tui {
                                     Event::FocusLost => {
                                         terminal_focused.store(false, Ordering::Relaxed);
                                     }
-                                    _ => {}
                                 }
                             }
                             Some(Err(_)) | None => {
@@ -341,8 +305,6 @@ impl Tui {
     /// inline viewport for restoration when leaving.
     pub fn enter_alt_screen(&mut self) -> Result<()> {
         let _ = execute!(self.terminal.backend_mut(), EnterAlternateScreen);
-        // Enable "alternate scroll" so terminals may translate wheel to arrows
-        let _ = execute!(self.terminal.backend_mut(), EnableAlternateScroll);
         if let Ok(size) = self.terminal.size() {
             self.alt_saved_viewport = Some(self.terminal.viewport_area);
             self.terminal.set_viewport_area(ratatui::layout::Rect::new(
@@ -359,8 +321,6 @@ impl Tui {
 
     /// Leave alternate screen and restore the previously saved inline viewport, if any.
     pub fn leave_alt_screen(&mut self) -> Result<()> {
-        // Disable alternate scroll when leaving alt-screen
-        let _ = execute!(self.terminal.backend_mut(), DisableAlternateScroll);
         let _ = execute!(self.terminal.backend_mut(), LeaveAlternateScreen);
         if let Some(saved) = self.alt_saved_viewport.take() {
             self.terminal.set_viewport_area(saved);
@@ -404,30 +364,13 @@ impl Tui {
 
             let size = terminal.size()?;
 
-            let mut area = terminal.viewport_area;
-            area.height = height.min(size.height);
-            area.width = size.width;
-            // If the viewport has expanded, scroll everything else up to make room.
-            if area.bottom() > size.height {
-                terminal
-                    .backend_mut()
-                    .scroll_region_up(0..area.top(), area.bottom() - size.height)?;
-                area.y = size.height - area.height;
-            }
+            let area = Rect::new(0, 0, size.width, height.min(size.height));
             if area != terminal.viewport_area {
                 // TODO(nornagon): probably this could be collapsed with the clear + set_viewport_area above.
                 terminal.clear()?;
                 terminal.set_viewport_area(area);
             }
 
-            if !self.pending_history_lines.is_empty() {
-                crate::insert_history::insert_history_lines(
-                    terminal,
-                    self.pending_history_lines.clone(),
-                )?;
-                self.pending_history_lines.clear();
-            }
-
             // Update the y position for suspending so Ctrl-Z can place the cursor correctly.
             #[cfg(unix)]
             {
diff --git a/codex-rs/tui2/src/tui/job_control.rs b/codex-rs/tui2/src/tui/job_control.rs
index 3680419489..0796e93f67 100644
--- a/codex-rs/tui2/src/tui/job_control.rs
+++ b/codex-rs/tui2/src/tui/job_control.rs
@@ -18,8 +18,6 @@ use ratatui::layout::Rect;
 
 use crate::key_hint;
 
-use super::DisableAlternateScroll;
-use super::EnableAlternateScroll;
 use super::Terminal;
 
 pub const SUSPEND_KEY: key_hint::KeyBinding = key_hint::ctrl(KeyCode::Char('z'));
@@ -63,8 +61,7 @@ impl SuspendContext {
     /// - Trigger SIGTSTP so the process can be resumed and continue drawing with the saved state.
     pub(crate) fn suspend(&self, alt_screen_active: &Arc<AtomicBool>) -> Result<()> {
         if alt_screen_active.load(Ordering::Relaxed) {
-            // Leave alt-screen so the terminal returns to the normal buffer while suspended; also turn off alt-scroll.
-            let _ = execute!(stdout(), DisableAlternateScroll);
+            // Leave alt-screen so the terminal returns to the normal buffer while suspended.
             let _ = execute!(stdout(), LeaveAlternateScreen);
             self.set_resume_action(ResumeAction::RestoreAlt);
         } else {
@@ -157,11 +154,10 @@ impl PreparedResumeAction {
         match self {
             PreparedResumeAction::RealignViewport(area) => {
                 terminal.set_viewport_area(area);
+                terminal.clear()?;
             }
             PreparedResumeAction::RestoreAltScreen => {
                 execute!(terminal.backend_mut(), EnterAlternateScreen)?;
-                // Enable "alternate scroll" so terminals may translate wheel to arrows
-                execute!(terminal.backend_mut(), EnableAlternateScroll)?;
                 if let Ok(size) = terminal.size() {
                     terminal.set_viewport_area(Rect::new(0, 0, size.width, size.height));
                     terminal.clear()?;