feat(cli/demo): add --demo developer message injection

code-rs/cli/src/main.rs

@@ -88,6 +88,10 @@ struct MultitoolCli {
     #[clap(long = "auto", global = true, default_value_t = false)]
     auto_drive: bool,
 
+    /// Developer-role message to prepend to every turn for demos.
+    #[clap(long = "demo", global = true, value_name = "TEXT")]
+    demo_developer_message: Option<String>,
+
     #[clap(subcommand)]
     subcommand: Option<Subcommand>,
 }
@@ -406,10 +410,12 @@ async fn cli_main(code_linux_sandbox_exe: Option<PathBuf>) -> anyhow::Result<()>
         config_overrides: root_config_overrides,
         mut interactive,
         auto_drive,
+        demo_developer_message,
         subcommand,
     } = MultitoolCli::parse();
 
     interactive.finalize_defaults();
+    interactive.demo_developer_message = demo_developer_message.clone();
 
     match subcommand {
         None => {
@@ -439,6 +445,7 @@ async fn cli_main(code_linux_sandbox_exe: Option<PathBuf>) -> anyhow::Result<()>
             if auto_drive {
                 exec_cli.auto_drive = true;
             }
+            exec_cli.demo_developer_message = demo_developer_message.clone();
             prepend_config_flags(
                 &mut exec_cli.config_overrides,
                 root_config_overrides.clone(),
@@ -450,6 +457,7 @@ async fn cli_main(code_linux_sandbox_exe: Option<PathBuf>) -> anyhow::Result<()>
             if !exec_cli.full_auto && !exec_cli.dangerously_bypass_approvals_and_sandbox {
                 exec_cli.full_auto = true;
             }
+            exec_cli.demo_developer_message = demo_developer_message.clone();
             prepend_config_flags(
                 &mut exec_cli.config_overrides,
                 root_config_overrides.clone(),

code-rs/core/src/codex.rs

@@ -222,6 +222,7 @@ pub(crate) struct TurnContext {
     pub(crate) cwd: PathBuf,
     pub(crate) base_instructions: Option<String>,
     pub(crate) user_instructions: Option<String>,
+    pub(crate) demo_developer_message: Option<String>,
     pub(crate) compact_prompt_override: Option<String>,
     pub(crate) approval_policy: AskForApproval,
     pub(crate) sandbox_policy: SandboxPolicy,
@@ -999,6 +1000,7 @@ impl Codex {
             notify: config.notify.clone(),
             cwd: config.cwd.clone(),
             resume_path: resume_path.clone(),
+            demo_developer_message: config.demo_developer_message.clone(),
         };
 
         let config = Arc::new(config);
@@ -1364,6 +1366,7 @@ pub(crate) struct Session {
     cwd: PathBuf,
     base_instructions: Option<String>,
     user_instructions: Option<String>,
+    demo_developer_message: Option<String>,
     compact_prompt_override: Option<String>,
     approval_policy: AskForApproval,
     sandbox_policy: SandboxPolicy,
@@ -2131,6 +2134,7 @@ impl Session {
             cwd: self.cwd.clone(),
             base_instructions: self.base_instructions.clone(),
             user_instructions: self.user_instructions.clone(),
+            demo_developer_message: self.demo_developer_message.clone(),
             compact_prompt_override: self.compact_prompt_override.clone(),
             approval_policy: self.approval_policy,
             sandbox_policy: self.sandbox_policy.clone(),
@@ -4263,6 +4267,7 @@ async fn submission_loop(
                 notify,
                 cwd,
                 resume_path,
+                demo_developer_message,
             } => {
                 debug!(
                     "Configuring session: model={model}; provider={provider:?}; resume={resume_path:?}"
@@ -4596,6 +4601,7 @@ async fn submission_loop(
                     tx_event: tx_event.clone(),
                     user_instructions: effective_user_instructions.clone(),
                     base_instructions,
+                    demo_developer_message: demo_developer_message.clone(),
                     compact_prompt_override: config.compact_prompt_override.clone(),
                     approval_policy,
                     sandbox_policy,
@@ -5131,6 +5137,7 @@ async fn spawn_review_thread(
         cwd: parent_turn_context.cwd.clone(),
         base_instructions: Some(REVIEW_PROMPT.to_string()),
         user_instructions: None,
+        demo_developer_message: parent_turn_context.demo_developer_message.clone(),
         compact_prompt_override: parent_turn_context.compact_prompt_override.clone(),
         approval_policy: parent_turn_context.approval_policy,
         sandbox_policy: parent_turn_context.sandbox_policy.clone(),
@@ -5749,7 +5756,11 @@ async fn run_turn(
             status_items, // Include status items with this request
             base_instructions_override: tc.base_instructions.clone(),
             include_additional_instructions: true,
-            prepend_developer_messages: Vec::new(),
+            prepend_developer_messages: tc
+                .demo_developer_message
+                .clone()
+                .into_iter()
+                .collect(),
             text_format: tc.text_format_override.clone(),
             model_override: None,
             model_family_override: None,

code-rs/core/src/config.rs

@@ -272,6 +272,10 @@ pub struct Config {
     /// User-provided instructions from AGENTS.md.
     pub user_instructions: Option<String>,
 
+    /// Optional developer-role message to prepend to every turn for demos.
+    /// Set by the CLI via `--demo`; not loaded from disk.
+    pub demo_developer_message: Option<String>,
+
     /// Base instructions override.
     pub base_instructions: Option<String>,
 
@@ -2898,6 +2902,7 @@ impl Config {
             notify: cfg.notify,
             notices: cfg.notice.unwrap_or_default(),
             user_instructions,
+            demo_developer_message: None,
             base_instructions,
             compact_prompt_override,
             mcp_servers: cfg.mcp_servers,

code-rs/core/src/protocol.rs

@@ -116,6 +116,12 @@ pub enum Op {
         /// Path to a rollout file to resume from.
         #[serde(skip_serializing_if = "Option::is_none")]
         resume_path: Option<std::path::PathBuf>,
+
+        /// Optional developer-role message to prepend to every turn for demos.
+        /// This is a CLI-only knob; it is not persisted in config files.
+        #[serde(skip_serializing_if = "Option::is_none")]
+        #[serde(default)]
+        demo_developer_message: Option<String>,
     },
 
     /// Abort current task.

code-rs/exec/src/cli.rs

@@ -76,6 +76,11 @@ pub struct Cli {
     #[clap(skip)]
     pub config_overrides: CliConfigOverrides,
 
+    /// Optional developer-role message to prepend to every turn for demos.
+    /// Set by the multitool root CLI via `--demo`.
+    #[clap(skip)]
+    pub demo_developer_message: Option<String>,
+
     /// Specifies color settings for use in the output.
     #[arg(long = "color", value_enum, default_value_t = Color::Auto)]
     pub color: Color,

code-rs/exec/src/lib.rs

@@ -276,6 +276,7 @@ pub async fn run_main(cli: Cli, code_linux_sandbox_exe: Option<PathBuf>) -> anyh
     };
 
     let mut config = Config::load_with_cli_overrides(cli_kv_overrides, overrides)?;
+    config.demo_developer_message = cli.demo_developer_message.clone();
     let slash_context = SlashContext {
         agents: &config.agents,
         subagent_commands: &config.subagent_commands,

code-rs/mcp-server/src/message_processor.rs

@@ -1628,6 +1628,7 @@ fn configure_session_op_from_config(config: &Config) -> Op {
         notify: config.notify.clone(),
         cwd: config.cwd.clone(),
         resume_path: None,
+        demo_developer_message: config.demo_developer_message.clone(),
     }
 }
 

code-rs/tui/src/chatwidget.rs

@@ -20634,6 +20634,7 @@ Have we met every part of this goal and is there no further work to do?"#
                 notify: self.config.notify.clone(),
                 cwd: self.config.cwd.clone(),
                 resume_path: None,
+                demo_developer_message: self.config.demo_developer_message.clone(),
             };
             self.submit_op(op);
 
@@ -21260,6 +21261,7 @@ Have we met every part of this goal and is there no further work to do?"#
             notify: self.config.notify.clone(),
             cwd: self.config.cwd.clone(),
             resume_path: None,
+            demo_developer_message: self.config.demo_developer_message.clone(),
         };
         self.submit_op(op);
     }
@@ -21284,6 +21286,7 @@ Have we met every part of this goal and is there no further work to do?"#
                 notify: self.config.notify.clone(),
                 cwd: self.config.cwd.clone(),
                 resume_path: None,
+                demo_developer_message: self.config.demo_developer_message.clone(),
             };
             self.submit_op(op);
         }
@@ -21488,6 +21491,7 @@ Have we met every part of this goal and is there no further work to do?"#
                 notify: self.config.notify.clone(),
                 cwd: self.config.cwd.clone(),
                 resume_path: None,
+                demo_developer_message: self.config.demo_developer_message.clone(),
             };
             let _ = self.code_op_tx.send(op);
         } else {
@@ -21630,6 +21634,7 @@ Have we met every part of this goal and is there no further work to do?"#
             notify: self.config.notify.clone(),
             cwd: self.config.cwd.clone(),
             resume_path: None,
+            demo_developer_message: self.config.demo_developer_message.clone(),
         };
 
         self.submit_op(op);
@@ -21669,6 +21674,7 @@ Have we met every part of this goal and is there no further work to do?"#
             notify: self.config.notify.clone(),
             cwd: self.config.cwd.clone(),
             resume_path: None,
+            demo_developer_message: self.config.demo_developer_message.clone(),
         };
 
         self.submit_op(op);
@@ -22719,6 +22725,7 @@ Have we met every part of this goal and is there no further work to do?"#
             notify: self.config.notify.clone(),
             cwd: self.config.cwd.clone(),
             resume_path: None,
+            demo_developer_message: self.config.demo_developer_message.clone(),
         };
         self.submit_op(op);
 
@@ -34163,6 +34170,7 @@ impl ChatWidget<'_> {
             notify: self.config.notify.clone(),
             cwd: self.config.cwd.clone(),
             resume_path: None,
+            demo_developer_message: self.config.demo_developer_message.clone(),
         };
         self.submit_op(op);
 

code-rs/tui/src/cli.rs

@@ -99,6 +99,11 @@ pub struct Cli {
     #[clap(skip)]
     pub config_overrides: CliConfigOverrides,
 
+    /// Optional developer-role message to prepend to every turn for demos.
+    /// Set by the multitool root CLI via `--demo`.
+    #[clap(skip)]
+    pub demo_developer_message: Option<String>,
+
     /// Start in resume picker mode when true (used by `code resume`).
     #[clap(skip)]
     pub resume_picker: bool,

code-rs/tui/src/lib.rs

@@ -480,6 +480,8 @@ pub async fn run_main(
         }
     };
 
+    config.demo_developer_message = cli.demo_developer_message.clone();
+
     let cli_model_override = cli.model.is_some()
         || cli_kv_overrides
             .iter()
@@ -508,7 +510,10 @@ pub async fn run_main(
                         cli_kv_overrides.clone(),
                         overrides.clone(),
                     ) {
-                        Ok(updated) => config = updated,
+                        Ok(updated) => {
+                            config = updated;
+                            config.demo_developer_message = cli.demo_developer_message.clone();
+                        }
                         Err(err) => {
                             eprintln!("Error reloading configuration: {err}");
                             std::process::exit(1);
@@ -532,7 +537,10 @@ pub async fn run_main(
                                 cli_kv_overrides.clone(),
                                 overrides.clone(),
                             ) {
-                                Ok(updated) => config = updated,
+                                Ok(updated) => {
+                                    config = updated;
+                                    config.demo_developer_message = cli.demo_developer_message.clone();
+                                }
                                 Err(err) => {
                                     eprintln!("Error reloading configuration: {err}");
                                     std::process::exit(1);