feat: add --json flag to codex exec

codex-rs/exec/src/cli.rs

@@ -51,6 +51,10 @@ pub struct Cli {
     #[arg(long = "color", value_enum, default_value_t = Color::Auto)]
     pub color: Color,
 
+    /// Print events to stdout as JSONL.
+    #[arg(long = "json", default_value_t = false)]
+    pub json: bool,
+
     /// Specifies file where the last message from the agent should be written.
     #[arg(long = "output-last-message")]
     pub last_message_file: Option<PathBuf>,

codex-rs/exec/src/event_processor.rs

@@ -30,7 +30,15 @@ use std::time::Instant;
 /// a limit so they can see the full transcript.
 const MAX_OUTPUT_LINES_FOR_EXEC_TOOL_CALL: usize = 20;
 
-pub(crate) struct EventProcessor {
+pub(crate) trait EventProcessor {
+    /// Print summary of effective configuration and user prompt.
+    fn print_config_summary(&mut self, config: &Config, prompt: &str);
+
+    /// Handle a single event emitted by the agent.
+    fn process_event(&mut self, event: Event);
+}
+
+pub(crate) struct EventProcessorWithHumanOutput {
     call_id_to_command: HashMap<String, ExecCommandBegin>,
     call_id_to_patch: HashMap<String, PatchApplyBegin>,
 
@@ -57,7 +65,7 @@ pub(crate) struct EventProcessor {
     reasoning_started: bool,
 }
 
-impl EventProcessor {
+impl EventProcessorWithHumanOutput {
     pub(crate) fn create_with_ansi(with_ansi: bool, config: &Config) -> Self {
         let call_id_to_command = HashMap::new();
         let call_id_to_patch = HashMap::new();
@@ -128,11 +136,11 @@ macro_rules! ts_println {
     }};
 }
 
-impl EventProcessor {
+impl EventProcessor for EventProcessorWithHumanOutput {
     /// Print a concise summary of the effective configuration that will be used
     /// for the session. This mirrors the information shown in the TUI welcome
     /// screen.
-    pub(crate) fn print_config_summary(&mut self, config: &Config, prompt: &str) {
+    fn print_config_summary(&mut self, config: &Config, prompt: &str) {
         const VERSION: &str = env!("CARGO_PKG_VERSION");
         ts_println!(
             self,
@@ -177,7 +185,7 @@ impl EventProcessor {
         );
     }
 
-    pub(crate) fn process_event(&mut self, event: Event) {
+    fn process_event(&mut self, event: Event) {
         let Event { id: _, msg } = event;
         match msg {
             EventMsg::Error(ErrorEvent { message }) => {

codex-rs/exec/src/event_processor_with_json_output.rs

@@ -0,0 +1,33 @@
+use codex_core::config::Config;
+use codex_core::protocol::Event;
+use codex_core::protocol::EventMsg;
+
+use crate::event_processor::EventProcessor;
+
+pub(crate) struct EventProcessorWithJsonOutput;
+
+impl EventProcessorWithJsonOutput {
+    pub fn new() -> Self {
+        Self {}
+    }
+}
+
+impl EventProcessor for EventProcessorWithJsonOutput {
+    fn print_config_summary(&mut self, _config: &Config, _prompt: &str) {
+        let _ = _config;
+        // Intentionally left blank – human summary not needed in JSON mode.
+    }
+
+    fn process_event(&mut self, event: Event) {
+        match event.msg {
+            EventMsg::AgentMessageDelta(_) | EventMsg::AgentReasoningDelta(_) => {
+                // Suppress streaming events in JSON mode.
+            }
+            _ => {
+                if let Ok(line) = serde_json::to_string(&event) {
+                    println!("{line}");
+                }
+            }
+        }
+    }
+}

codex-rs/exec/src/lib.rs

@@ -1,5 +1,6 @@
 mod cli;
 mod event_processor;
+mod event_processor_with_json_output;
 
 use std::io::IsTerminal;
 use std::io::Read;
@@ -19,12 +20,15 @@ use codex_core::protocol::InputItem;
 use codex_core::protocol::Op;
 use codex_core::protocol::TaskCompleteEvent;
 use codex_core::util::is_inside_git_repo;
-use event_processor::EventProcessor;
+use event_processor::EventProcessorWithHumanOutput;
+use event_processor_with_json_output::EventProcessorWithJsonOutput;
 use tracing::debug;
 use tracing::error;
 use tracing::info;
 use tracing_subscriber::EnvFilter;
 
+use crate::event_processor::EventProcessor;
+
 pub async fn run_main(cli: Cli, codex_linux_sandbox_exe: Option<PathBuf>) -> anyhow::Result<()> {
     let Cli {
         images,
@@ -36,6 +40,7 @@ pub async fn run_main(cli: Cli, codex_linux_sandbox_exe: Option<PathBuf>) -> any
         skip_git_repo_check,
         color,
         last_message_file,
+        json: json_mode,
         sandbox_mode: sandbox_mode_cli_arg,
         prompt,
         config_overrides,
@@ -115,9 +120,16 @@ pub async fn run_main(cli: Cli, codex_linux_sandbox_exe: Option<PathBuf>) -> any
     };
 
     let config = Config::load_with_cli_overrides(cli_kv_overrides, overrides)?;
-    let mut event_processor = EventProcessor::create_with_ansi(stdout_with_ansi, &config);
-    // Print the effective configuration and prompt so users can see what Codex
-    // is using.
+    let mut event_processor: Box<dyn EventProcessor> = if json_mode {
+        Box::new(EventProcessorWithJsonOutput::new())
+    } else {
+        Box::new(EventProcessorWithHumanOutput::create_with_ansi(
+            stdout_with_ansi,
+            &config,
+        ))
+    };
+
+    // Human processor prints summary; JSON processor is a no-op.
     event_processor.print_config_summary(&config, &prompt);
 
     if !skip_git_repo_check && !is_inside_git_repo(&config) {