cloud: codex cloud exec (#5060)

By analogy to `codex exec`, this kicks off a task in codex cloud
noninteractively.

codex-rs/cloud-tasks/src/cli.rs

@@ -1,3 +1,4 @@
+use clap::Args;
 use clap::Parser;
 use codex_common::CliConfigOverrides;
 
@@ -6,4 +7,43 @@ use codex_common::CliConfigOverrides;
 pub struct Cli {
     #[clap(skip)]
     pub config_overrides: CliConfigOverrides,
+
+    #[command(subcommand)]
+    pub command: Option<Command>,
+}
+
+#[derive(Debug, clap::Subcommand)]
+pub enum Command {
+    /// Submit a new Codex Cloud task without launching the TUI.
+    Exec(ExecCommand),
+}
+
+#[derive(Debug, Args)]
+pub struct ExecCommand {
+    /// Task prompt to run in Codex Cloud.
+    #[arg(value_name = "QUERY")]
+    pub query: Option<String>,
+
+    /// Target environment identifier (see `codex cloud` to browse).
+    #[arg(long = "env", value_name = "ENV_ID")]
+    pub environment: String,
+
+    /// Number of assistant attempts (best-of-N).
+    #[arg(
+        long = "attempts",
+        default_value_t = 1usize,
+        value_parser = parse_attempts
+    )]
+    pub attempts: usize,
+}
+
+fn parse_attempts(input: &str) -> Result<usize, String> {
+    let value: usize = input
+        .parse()
+        .map_err(|_| "attempts must be an integer between 1 and 4".to_string())?;
+    if (1..=4).contains(&value) {
+        Ok(value)
+    } else {
+        Err("attempts must be between 1 and 4".to_string())
+    }
 }