fix: disable debouncing RequestRedraw in the TUI for now

changed the default debounce rate to 10ms because typing was laggy.

Before:


https://github.com/user-attachments/assets/e5d15fcb-6a2b-4837-b2b4-c3dcb4cc3409

After



https://github.com/user-attachments/assets/6f0005eb-fd49-4130-ba68-635ee0f2831f

.vscode/launch.json

@@ -0,0 +1,18 @@
+{
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "type": "lldb",
+            "request": "launch",
+            "name": "Cargo launch",
+            "cargo": {
+                "cwd": "${workspaceFolder}/codex-rs",
+                "args": [
+                    "build",
+                    "--bin=codex-tui"
+                ]
+            },
+            "args": []
+        }
+    ]
+}

.vscode/settings.json

@@ -0,0 +1,10 @@
+{
+    "rust-analyzer.checkOnSave": true,
+    "rust-analyzer.check.command": "clippy",
+    "rust-analyzer.check.extraArgs": ["--all-features", "--tests"],
+    "rust-analyzer.rustfmt.extraArgs": ["--config", "imports_granularity=Item"],
+    "[rust]": {
+        "editor.defaultFormatter": "rust-lang.rust-analyzer",
+        "editor.formatOnSave": true,
+    }
+}

AGENTS.md

@@ -3,3 +3,7 @@
 In the codex-rs folder where the rust code lives:
 
 - Never add or modify any code related to `CODEX_SANDBOX_NETWORK_DISABLED_ENV_VAR`. You operate in a sandbox where `CODEX_SANDBOX_NETWORK_DISABLED=1` will be set whenever you use the `shell` tool. Any existing code that uses `CODEX_SANDBOX_NETWORK_DISABLED_ENV_VAR` was authored with this fact in mind. It is often used to early exit out of tests that the author knew you would not be able to run given your sandbox limitations.
+
+Before creating a pull request with changes to `codex-rs`, run `just fmt` (in `codex-rs` directory) to format the code and `just fix` (in `codex-rs` directory) to fix any linter issues in the code, ensure the test suite passes by running `cargo test --all-features` in the `codex-rs` directory.
+
+When making individual changes prefer running tests on individual files or projects first.

codex-cli/bin/codex.js

@@ -15,7 +15,6 @@
  *      current platform / architecture, an error is thrown.
  */
 
-import { spawnSync } from "child_process";
 import fs from "fs";
 import path from "path";
 import { fileURLToPath, pathToFileURL } from "url";
@@ -35,7 +34,7 @@ const wantsNative = fs.existsSync(path.join(__dirname, "use-native")) ||
     : false);
 
 // Try native binary if requested.
-if (wantsNative) {
+if (wantsNative && process.platform !== 'win32') {
   const { platform, arch } = process;
 
   let targetTriple = null;
@@ -74,22 +73,76 @@ if (wantsNative) {
   }
 
   const binaryPath = path.join(__dirname, "..", "bin", `codex-${targetTriple}`);
-  const result = spawnSync(binaryPath, process.argv.slice(2), {
+
+  // Use an asynchronous spawn instead of spawnSync so that Node is able to
+  // respond to signals (e.g. Ctrl-C / SIGINT) while the native binary is
+  // executing. This allows us to forward those signals to the child process
+  // and guarantees that when either the child terminates or the parent
+  // receives a fatal signal, both processes exit in a predictable manner.
+  const { spawn } = await import("child_process");
+
+  const child = spawn(binaryPath, process.argv.slice(2), {
     stdio: "inherit",
   });
 
-  const exitCode = typeof result.status === "number" ? result.status : 1;
-  process.exit(exitCode);
-}
+  child.on("error", (err) => {
+    // Typically triggered when the binary is missing or not executable.
+    // Re-throwing here will terminate the parent with a non-zero exit code
+    // while still printing a helpful stack trace.
+    // eslint-disable-next-line no-console
+    console.error(err);
+    process.exit(1);
+  });
 
-// Fallback: execute the original JavaScript CLI.
+  // Forward common termination signals to the child so that it shuts down
+  // gracefully. In the handler we temporarily disable the default behavior of
+  // exiting immediately; once the child has been signaled we simply wait for
+  // its exit event which will in turn terminate the parent (see below).
+  const forwardSignal = (signal) => {
+    if (child.killed) {
+      return;
+    }
+    try {
+      child.kill(signal);
+    } catch {
+      /* ignore */
+    }
+  };
 
-// Resolve the path to the compiled CLI bundle
-const cliPath = path.resolve(__dirname, "../dist/cli.js");
-const cliUrl = pathToFileURL(cliPath).href;
+  ["SIGINT", "SIGTERM", "SIGHUP"].forEach((sig) => {
+    process.on(sig, () => forwardSignal(sig));
+  });
 
-// Load and execute the CLI
-(async () => {
+  // When the child exits, mirror its termination reason in the parent so that
+  // shell scripts and other tooling observe the correct exit status.
+  // Wrap the lifetime of the child process in a Promise so that we can await
+  // its termination in a structured way. The Promise resolves with an object
+  // describing how the child exited: either via exit code or due to a signal.
+  const childResult = await new Promise((resolve) => {
+    child.on("exit", (code, signal) => {
+      if (signal) {
+        resolve({ type: "signal", signal });
+      } else {
+        resolve({ type: "code", exitCode: code ?? 1 });
+      }
+    });
+  });
+
+  if (childResult.type === "signal") {
+    // Re-emit the same signal so that the parent terminates with the expected
+    // semantics (this also sets the correct exit code of 128 + n).
+    process.kill(process.pid, childResult.signal);
+  } else {
+    process.exit(childResult.exitCode);
+  }
+} else {
+  // Fallback: execute the original JavaScript CLI.
+
+  // Resolve the path to the compiled CLI bundle
+  const cliPath = path.resolve(__dirname, "../dist/cli.js");
+  const cliUrl = pathToFileURL(cliPath).href;
+
+  // Load and execute the CLI
   try {
     await import(cliUrl);
   } catch (err) {
@@ -97,4 +150,4 @@ const cliUrl = pathToFileURL(cliPath).href;
     console.error(err);
     process.exit(1);
   }
-})();
+}

codex-rs/Cargo.lock

@@ -399,6 +399,15 @@ version = "2.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6099cdc01846bc367c4e7dd630dc5966dccf36b652fae7a74e17b640411a91b2"
 
+[[package]]
+name = "block-buffer"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "bstr"
 version = "1.12.0"
@@ -671,6 +680,7 @@ dependencies = [
  "seccompiler",
  "serde",
  "serde_json",
+ "sha1",
  "strum_macros 0.27.1",
  "tempfile",
  "thiserror 2.0.12",
@@ -683,6 +693,7 @@ dependencies = [
  "tree-sitter",
  "tree-sitter-bash",
  "uuid",
+ "walkdir",
  "wildmatch",
  "wiremock",
 ]
@@ -932,6 +943,15 @@ version = "0.8.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "773648b94d0e5d620f64f280777445740e61fe701025087ec8b57f45c791888b"
 
+[[package]]
+name = "cpufeatures"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59ed5838eebb26a2bb2e58f6d5b5316989ae9d08bab10e0e6d103e656d1b0280"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "crc32fast"
 version = "1.4.2"
@@ -1006,6 +1026,16 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "460fbee9c2c2f33933d720630a6a0bac33ba7053db5344fac858d4b8952d77d5"
 
+[[package]]
+name = "crypto-common"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bfb12502f3fc46cca1bb51ac28df9d618d813cdc3d2f25b9fe775a34af26bb3"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
 [[package]]
 name = "ctor"
 version = "0.1.26"
@@ -1156,6 +1186,16 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6184e33543162437515c2e2b48714794e37845ec9851711914eec9d308f6ebe8"
 
+[[package]]
+name = "digest"
+version = "0.10.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+]
+
 [[package]]
 name = "dirs"
 version = "6.0.0"
@@ -1645,6 +1685,16 @@ dependencies = [
  "byteorder",
 ]
 
+[[package]]
+name = "generic-array"
+version = "0.14.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
 [[package]]
 name = "getopts"
 version = "0.2.23"
@@ -3944,6 +3994,17 @@ dependencies = [
  "syn 2.0.104",
 ]
 
+[[package]]
+name = "sha1"
+version = "0.10.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e3bf829a2d51ab4a5ddf1352d8470c140cadc8301b2ae1789db023f01cedd6ba"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
 [[package]]
 name = "sharded-slab"
 version = "0.1.7"
@@ -4851,6 +4912,12 @@ dependencies = [
  "unicode-width 0.2.0",
 ]
 
+[[package]]
+name = "typenum"
+version = "1.18.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1dccffe3ce07af9386bfd29e80c0ab1a8205a2fc34e4bcd40364df902cfa8f3f"
+
 [[package]]
 name = "unicase"
 version = "2.8.1"

codex-rs/core/Cargo.toml

@@ -28,6 +28,7 @@ rand = "0.9"
 reqwest = { version = "0.12", features = ["json", "stream"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+sha1 = "0.10.6"
 strum_macros = "0.27.1"
 thiserror = "2.0.12"
 time = { version = "0.3", features = ["formatting", "local-offset", "macros"] }
@@ -65,4 +66,5 @@ predicates = "3"
 pretty_assertions = "1.4.1"
 tempfile = "3"
 tokio-test = "0.4"
+walkdir = "2.5.0"
 wiremock = "0.6"

codex-rs/core/src/chat_completions.rs

@@ -134,7 +134,7 @@ pub(crate) async fn stream_chat_completions(
 
         match res {
             Ok(resp) if resp.status().is_success() => {
-                let (tx_event, rx_event) = mpsc::channel::<Result<ResponseEvent>>(16);
+                let (tx_event, rx_event) = mpsc::channel::<Result<ResponseEvent>>(1600);
                 let stream = resp.bytes_stream().map_err(CodexErr::Reqwest);
                 tokio::spawn(process_chat_sse(stream, tx_event));
                 return Ok(ResponseStream { rx_event });
@@ -426,6 +426,12 @@ where
                     // will never appear in a Chat Completions stream.
                     continue;
                 }
+                Poll::Ready(Some(Ok(ResponseEvent::OutputTextDelta(_))))
+                | Poll::Ready(Some(Ok(ResponseEvent::ReasoningSummaryDelta(_)))) => {
+                    // Deltas are ignored here since aggregation waits for the
+                    // final OutputItemDone.
+                    continue;
+                }
             }
         }
     }

codex-rs/core/src/client.rs

@@ -125,6 +125,7 @@ impl ModelClient {
             reasoning,
             previous_response_id: prompt.prev_id.clone(),
             store: prompt.store,
+            // TODO: make this configurable
             stream: true,
         };
 
@@ -148,7 +149,7 @@ impl ModelClient {
             let res = req_builder.send().await;
             match res {
                 Ok(resp) if resp.status().is_success() => {
-                    let (tx_event, rx_event) = mpsc::channel::<Result<ResponseEvent>>(16);
+                    let (tx_event, rx_event) = mpsc::channel::<Result<ResponseEvent>>(1600);
 
                     // spawn task to process SSE
                     let stream = resp.bytes_stream().map_err(CodexErr::Reqwest);
@@ -205,6 +206,7 @@ struct SseEvent {
     kind: String,
     response: Option<Value>,
     item: Option<Value>,
+    delta: Option<String>,
 }
 
 #[derive(Debug, Deserialize)]
@@ -337,6 +339,22 @@ where
                     return;
                 }
             }
+            "response.output_text.delta" => {
+                if let Some(delta) = event.delta {
+                    let event = ResponseEvent::OutputTextDelta(delta);
+                    if tx_event.send(Ok(event)).await.is_err() {
+                        return;
+                    }
+                }
+            }
+            "response.reasoning_summary_text.delta" => {
+                if let Some(delta) = event.delta {
+                    let event = ResponseEvent::ReasoningSummaryDelta(delta);
+                    if tx_event.send(Ok(event)).await.is_err() {
+                        return;
+                    }
+                }
+            }
             "response.created" => {
                 if event.response.is_some() {
                     let _ = tx_event.send(Ok(ResponseEvent::Created {})).await;
@@ -360,10 +378,8 @@ where
             | "response.function_call_arguments.delta"
             | "response.in_progress"
             | "response.output_item.added"
-            | "response.output_text.delta"
             | "response.output_text.done"
             | "response.reasoning_summary_part.added"
-            | "response.reasoning_summary_text.delta"
             | "response.reasoning_summary_text.done" => {
                 // Currently, we ignore these events, but we handle them
                 // separately to skip the logging message in the `other` case.
@@ -375,7 +391,7 @@ where
 
 /// used in tests to stream from a text SSE file
 async fn stream_from_fixture(path: impl AsRef<Path>) -> Result<ResponseStream> {
-    let (tx_event, rx_event) = mpsc::channel::<Result<ResponseEvent>>(16);
+    let (tx_event, rx_event) = mpsc::channel::<Result<ResponseEvent>>(1600);
     let f = std::fs::File::open(path.as_ref())?;
     let lines = std::io::BufReader::new(f).lines();
 

codex-rs/core/src/client_common.rs

@@ -57,6 +57,8 @@ pub enum ResponseEvent {
         response_id: String,
         token_usage: Option<TokenUsage>,
     },
+    OutputTextDelta(String),
+    ReasoningSummaryDelta(String),
 }
 
 #[derive(Debug, Serialize)]

codex-rs/core/src/codex.rs

@@ -51,7 +51,6 @@ use crate::exec::process_exec_tool_call;
 use crate::exec_env::create_env;
 use crate::flags::OPENAI_STREAM_MAX_RETRIES;
 use crate::mcp_connection_manager::McpConnectionManager;
-use crate::mcp_connection_manager::try_parse_fully_qualified_tool_name;
 use crate::mcp_tool_call::handle_mcp_tool_call;
 use crate::models::ContentItem;
 use crate::models::FunctionCallOutputPayload;
@@ -61,7 +60,9 @@ use crate::models::ResponseInputItem;
 use crate::models::ResponseItem;
 use crate::models::ShellToolCallParams;
 use crate::project_doc::get_user_instructions;
+use crate::protocol::AgentMessageDeltaEvent;
 use crate::protocol::AgentMessageEvent;
+use crate::protocol::AgentReasoningDeltaEvent;
 use crate::protocol::AgentReasoningEvent;
 use crate::protocol::ApplyPatchApprovalRequestEvent;
 use crate::protocol::AskForApproval;
@@ -103,7 +104,7 @@ impl Codex {
     /// submitted to start the session.
     pub async fn spawn(config: Config, ctrl_c: Arc<Notify>) -> CodexResult<(Codex, String)> {
         let (tx_sub, rx_sub) = async_channel::bounded(64);
-        let (tx_event, rx_event) = async_channel::bounded(64);
+        let (tx_event, rx_event) = async_channel::bounded(1600);
 
         let instructions = get_user_instructions(&config).await;
         let configure_session = Op::ConfigureSession {
@@ -1121,15 +1122,8 @@ async fn try_run_turn(
 
     let mut stream = sess.client.clone().stream(&prompt).await?;
 
-    // Buffer all the incoming messages from the stream first, then execute them.
-    // If we execute a function call in the middle of handling the stream, it can time out.
-    let mut input = Vec::new();
-    while let Some(event) = stream.next().await {
-        input.push(event?);
-    }
-
     let mut output = Vec::new();
-    for event in input {
+    while let Some(Ok(event)) = stream.next().await {
         match event {
             ResponseEvent::Created => {
                 let mut state = sess.state.lock().unwrap();
@@ -1172,6 +1166,20 @@ async fn try_run_turn(
                 state.previous_response_id = Some(response_id);
                 break;
             }
+            ResponseEvent::OutputTextDelta(delta) => {
+                let event = Event {
+                    id: sub_id.to_string(),
+                    msg: EventMsg::AgentMessageDelta(AgentMessageDeltaEvent { delta }),
+                };
+                sess.tx_event.send(event).await.ok();
+            }
+            ResponseEvent::ReasoningSummaryDelta(delta) => {
+                let event = Event {
+                    id: sub_id.to_string(),
+                    msg: EventMsg::AgentReasoningDelta(AgentReasoningDeltaEvent { delta }),
+                };
+                sess.tx_event.send(event).await.ok();
+            }
         }
     }
     Ok(output)
@@ -1283,7 +1291,7 @@ async fn handle_function_call(
             handle_container_exec_with_params(params, sess, sub_id, call_id).await
         }
         _ => {
-            match try_parse_fully_qualified_tool_name(&name) {
+            match sess.mcp_connection_manager.parse_tool_name(&name) {
                 Some((server, tool_name)) => {
                     // TODO(mbolin): Determine appropriate timeout for tool call.
                     let timeout = None;

codex-rs/core/src/mcp_connection_manager.rs

@@ -7,6 +7,7 @@
 //! `"<server><MCP_TOOL_NAME_DELIMITER><tool>"` as the key.
 
 use std::collections::HashMap;
+use std::collections::HashSet;
 use std::time::Duration;
 
 use anyhow::Context;
@@ -16,8 +17,12 @@ use codex_mcp_client::McpClient;
 use mcp_types::ClientCapabilities;
 use mcp_types::Implementation;
 use mcp_types::Tool;
+
+use sha1::Digest;
+use sha1::Sha1;
 use tokio::task::JoinSet;
 use tracing::info;
+use tracing::warn;
 
 use crate::config_types::McpServerConfig;
 
@@ -26,7 +31,8 @@ use crate::config_types::McpServerConfig;
 ///
 /// OpenAI requires tool names to conform to `^[a-zA-Z0-9_-]+$`, so we must
 /// choose a delimiter from this character set.
-const MCP_TOOL_NAME_DELIMITER: &str = "__OAI_CODEX_MCP__";
+const MCP_TOOL_NAME_DELIMITER: &str = "__";
+const MAX_TOOL_NAME_LENGTH: usize = 64;
 
 /// Timeout for the `tools/list` request.
 const LIST_TOOLS_TIMEOUT: Duration = Duration::from_secs(10);
@@ -35,16 +41,42 @@ const LIST_TOOLS_TIMEOUT: Duration = Duration::from_secs(10);
 /// spawned successfully.
 pub type ClientStartErrors = HashMap<String, anyhow::Error>;
 
-fn fully_qualified_tool_name(server: &str, tool: &str) -> String {
-    format!("{server}{MCP_TOOL_NAME_DELIMITER}{tool}")
+fn qualify_tools(tools: Vec<ToolInfo>) -> HashMap<String, ToolInfo> {
+    let mut used_names = HashSet::new();
+    let mut qualified_tools = HashMap::new();
+    for tool in tools {
+        let mut qualified_name = format!(
+            "{}{}{}",
+            tool.server_name, MCP_TOOL_NAME_DELIMITER, tool.tool_name
+        );
+        if qualified_name.len() > MAX_TOOL_NAME_LENGTH {
+            let mut hasher = Sha1::new();
+            hasher.update(qualified_name.as_bytes());
+            let sha1 = hasher.finalize();
+            let sha1_str = format!("{sha1:x}");
+
+            // Truncate to make room for the hash suffix
+            let prefix_len = MAX_TOOL_NAME_LENGTH - sha1_str.len();
+
+            qualified_name = format!("{}{}", &qualified_name[..prefix_len], sha1_str);
+        }
+
+        if used_names.contains(&qualified_name) {
+            warn!("skipping duplicated tool {}", qualified_name);
+            continue;
+        }
+
+        used_names.insert(qualified_name.clone());
+        qualified_tools.insert(qualified_name, tool);
+    }
+
+    qualified_tools
 }
 
-pub(crate) fn try_parse_fully_qualified_tool_name(fq_name: &str) -> Option<(String, String)> {
-    let (server, tool) = fq_name.split_once(MCP_TOOL_NAME_DELIMITER)?;
-    if server.is_empty() || tool.is_empty() {
-        return None;
-    }
-    Some((server.to_string(), tool.to_string()))
+struct ToolInfo {
+    server_name: String,
+    tool_name: String,
+    tool: Tool,
 }
 
 /// A thin wrapper around a set of running [`McpClient`] instances.
@@ -57,7 +89,7 @@ pub(crate) struct McpConnectionManager {
     clients: HashMap<String, std::sync::Arc<McpClient>>,
 
     /// Fully qualified tool name -> tool instance.
-    tools: HashMap<String, Tool>,
+    tools: HashMap<String, ToolInfo>,
 }
 
 impl McpConnectionManager {
@@ -79,9 +111,19 @@ impl McpConnectionManager {
 
         // Launch all configured servers concurrently.
         let mut join_set = JoinSet::new();
+        let mut errors = ClientStartErrors::new();
 
         for (server_name, cfg) in mcp_servers {
-            // TODO: Verify server name: require `^[a-zA-Z0-9_-]+$`?
+            // Validate server name before spawning
+            if !is_valid_mcp_server_name(&server_name) {
+                let error = anyhow::anyhow!(
+                    "invalid server name '{}': must match pattern ^[a-zA-Z0-9_-]+$",
+                    server_name
+                );
+                errors.insert(server_name, error);
+                continue;
+            }
+
             join_set.spawn(async move {
                 let McpServerConfig { command, args, env } = cfg;
                 let client_res = McpClient::new_stdio_client(command, args, env).await;
@@ -117,7 +159,6 @@ impl McpConnectionManager {
 
         let mut clients: HashMap<String, std::sync::Arc<McpClient>> =
             HashMap::with_capacity(join_set.len());
-        let mut errors = ClientStartErrors::new();
 
         while let Some(res) = join_set.join_next().await {
             let (server_name, client_res) = res?; // JoinError propagation
@@ -132,7 +173,9 @@ impl McpConnectionManager {
             }
         }
 
-        let tools = list_all_tools(&clients).await?;
+        let all_tools = list_all_tools(&clients).await?;
+
+        let tools = qualify_tools(all_tools);
 
         Ok((Self { clients, tools }, errors))
     }
@@ -140,7 +183,10 @@ impl McpConnectionManager {
     /// Returns a single map that contains **all** tools. Each key is the
     /// fully-qualified name for the tool.
     pub fn list_all_tools(&self) -> HashMap<String, Tool> {
-        self.tools.clone()
+        self.tools
+            .iter()
+            .map(|(name, tool)| (name.clone(), tool.tool.clone()))
+            .collect()
     }
 
     /// Invoke the tool indicated by the (server, tool) pair.
@@ -162,13 +208,19 @@ impl McpConnectionManager {
             .await
             .with_context(|| format!("tool call failed for `{server}/{tool}`"))
     }
+
+    pub fn parse_tool_name(&self, tool_name: &str) -> Option<(String, String)> {
+        self.tools
+            .get(tool_name)
+            .map(|tool| (tool.server_name.clone(), tool.tool_name.clone()))
+    }
 }
 
 /// Query every server for its available tools and return a single map that
 /// contains **all** tools. Each key is the fully-qualified name for the tool.
-pub async fn list_all_tools(
+async fn list_all_tools(
     clients: &HashMap<String, std::sync::Arc<McpClient>>,
-) -> Result<HashMap<String, Tool>> {
+) -> Result<Vec<ToolInfo>> {
     let mut join_set = JoinSet::new();
 
     // Spawn one task per server so we can query them concurrently. This
@@ -185,18 +237,19 @@ pub async fn list_all_tools(
         });
     }
 
-    let mut aggregated: HashMap<String, Tool> = HashMap::with_capacity(join_set.len());
+    let mut aggregated: Vec<ToolInfo> = Vec::with_capacity(join_set.len());
 
     while let Some(join_res) = join_set.join_next().await {
         let (server_name, list_result) = join_res?;
         let list_result = list_result?;
 
         for tool in list_result.tools {
-            // TODO(mbolin): escape tool names that contain invalid characters.
-            let fq_name = fully_qualified_tool_name(&server_name, &tool.name);
-            if aggregated.insert(fq_name.clone(), tool).is_some() {
-                panic!("tool name collision for '{fq_name}': suspicious");
-            }
+            let tool_info = ToolInfo {
+                server_name: server_name.clone(),
+                tool_name: tool.name.clone(),
+                tool,
+            };
+            aggregated.push(tool_info);
         }
     }
 
@@ -208,3 +261,97 @@ pub async fn list_all_tools(
 
     Ok(aggregated)
 }
+
+fn is_valid_mcp_server_name(server_name: &str) -> bool {
+    !server_name.is_empty()
+        && server_name
+            .chars()
+            .all(|c| c.is_ascii_alphanumeric() || c == '_' || c == '-')
+}
+
+#[cfg(test)]
+#[allow(clippy::unwrap_used)]
+mod tests {
+    use super::*;
+    use mcp_types::ToolInputSchema;
+
+    fn create_test_tool(server_name: &str, tool_name: &str) -> ToolInfo {
+        ToolInfo {
+            server_name: server_name.to_string(),
+            tool_name: tool_name.to_string(),
+            tool: Tool {
+                annotations: None,
+                description: Some(format!("Test tool: {tool_name}")),
+                input_schema: ToolInputSchema {
+                    properties: None,
+                    required: None,
+                    r#type: "object".to_string(),
+                },
+                name: tool_name.to_string(),
+            },
+        }
+    }
+
+    #[test]
+    fn test_qualify_tools_short_non_duplicated_names() {
+        let tools = vec![
+            create_test_tool("server1", "tool1"),
+            create_test_tool("server1", "tool2"),
+        ];
+
+        let qualified_tools = qualify_tools(tools);
+
+        assert_eq!(qualified_tools.len(), 2);
+        assert!(qualified_tools.contains_key("server1__tool1"));
+        assert!(qualified_tools.contains_key("server1__tool2"));
+    }
+
+    #[test]
+    fn test_qualify_tools_duplicated_names_skipped() {
+        let tools = vec![
+            create_test_tool("server1", "duplicate_tool"),
+            create_test_tool("server1", "duplicate_tool"),
+        ];
+
+        let qualified_tools = qualify_tools(tools);
+
+        // Only the first tool should remain, the second is skipped
+        assert_eq!(qualified_tools.len(), 1);
+        assert!(qualified_tools.contains_key("server1__duplicate_tool"));
+    }
+
+    #[test]
+    fn test_qualify_tools_long_names_same_server() {
+        let server_name = "my_server";
+
+        let tools = vec![
+            create_test_tool(
+                server_name,
+                "extremely_lengthy_function_name_that_absolutely_surpasses_all_reasonable_limits",
+            ),
+            create_test_tool(
+                server_name,
+                "yet_another_extremely_lengthy_function_name_that_absolutely_surpasses_all_reasonable_limits",
+            ),
+        ];
+
+        let qualified_tools = qualify_tools(tools);
+
+        assert_eq!(qualified_tools.len(), 2);
+
+        let mut keys: Vec<_> = qualified_tools.keys().cloned().collect();
+        keys.sort();
+
+        assert_eq!(keys[0].len(), 64);
+        assert_eq!(
+            keys[0],
+            "my_server__extremely_lena02e507efc5a9de88637e436690364fd4219e4ef"
+        );
+
+        assert_eq!(keys[1].len(), 64);
+        assert_eq!(
+            keys[1],
+            "my_server__yet_another_e1c3987bd9c50b826cbe1687966f79f0c602d19ca"
+        );
+    }
+}

codex-rs/core/src/protocol.rs

@@ -282,9 +282,15 @@ pub enum EventMsg {
     /// Agent text output message
     AgentMessage(AgentMessageEvent),
 
+    /// Agent text output delta message
+    AgentMessageDelta(AgentMessageDeltaEvent),
+
     /// Reasoning event from agent.
     AgentReasoning(AgentReasoningEvent),
 
+    /// Agent reasoning delta event from agent.
+    AgentReasoningDelta(AgentReasoningDeltaEvent),
+
     /// Ack the client's configure message.
     SessionConfigured(SessionConfiguredEvent),
 
@@ -340,11 +346,21 @@ pub struct AgentMessageEvent {
     pub message: String,
 }
 
+#[derive(Debug, Clone, Deserialize, Serialize)]
+pub struct AgentMessageDeltaEvent {
+    pub delta: String,
+}
+
 #[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct AgentReasoningEvent {
     pub text: String,
 }
 
+#[derive(Debug, Clone, Deserialize, Serialize)]
+pub struct AgentReasoningDeltaEvent {
+    pub delta: String,
+}
+
 #[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct McpToolCallBeginEvent {
     /// Identifier so this can be paired with the McpToolCallEnd event.

codex-rs/core/src/rollout.rs

@@ -153,13 +153,15 @@ struct LogFileInfo {
 }
 
 fn create_log_file(config: &Config, session_id: Uuid) -> std::io::Result<LogFileInfo> {
-    // Resolve ~/.codex/sessions and create it if missing.
-    let mut dir = config.codex_home.clone();
-    dir.push(SESSIONS_SUBDIR);
-    fs::create_dir_all(&dir)?;
-
+    // Resolve ~/.codex/sessions/YYYY/MM/DD and create it if missing.
     let timestamp = OffsetDateTime::now_local()
         .map_err(|e| IoError::other(format!("failed to get local time: {e}")))?;
+    let mut dir = config.codex_home.clone();
+    dir.push(SESSIONS_SUBDIR);
+    dir.push(timestamp.year().to_string());
+    dir.push(format!("{:02}", u8::from(timestamp.month())));
+    dir.push(format!("{:02}", timestamp.day()));
+    fs::create_dir_all(&dir)?;
 
     // Custom format for YYYY-MM-DDThh-mm-ss. Use `-` instead of `:` for
     // compatibility with filesystems that do not allow colons in filenames.

codex-rs/core/tests/cli_stream.rs

@@ -2,7 +2,12 @@
 
 use assert_cmd::Command as AssertCommand;
 use codex_core::exec::CODEX_SANDBOX_NETWORK_DISABLED_ENV_VAR;
+use serde_json::Value;
+use std::time::Duration;
+use std::time::Instant;
 use tempfile::TempDir;
+use uuid::Uuid;
+use walkdir::WalkDir;
 use wiremock::Mock;
 use wiremock::MockServer;
 use wiremock::ResponseTemplate;
@@ -71,8 +76,8 @@ async fn chat_mode_stream_cli() {
     println!("Stderr:\n{}", String::from_utf8_lossy(&output.stderr));
     assert!(output.status.success());
     let stdout = String::from_utf8_lossy(&output.stdout);
-    assert!(stdout.contains("hi"));
-    assert_eq!(stdout.matches("hi").count(), 1);
+    let hi_lines = stdout.lines().filter(|line| line.trim() == "hi").count();
+    assert_eq!(hi_lines, 1, "Expected exactly one line with 'hi'");
 
     server.verify().await;
 }
@@ -117,3 +122,154 @@ async fn responses_api_stream_cli() {
     let stdout = String::from_utf8_lossy(&output.stdout);
     assert!(stdout.contains("fixture hello"));
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn integration_creates_and_checks_session_file() {
+    // Honor sandbox network restrictions for CI parity with the other tests.
+    if std::env::var(CODEX_SANDBOX_NETWORK_DISABLED_ENV_VAR).is_ok() {
+        println!(
+            "Skipping test because it cannot execute when network is disabled in a Codex sandbox."
+        );
+        return;
+    }
+
+    // 1. Temp home so we read/write isolated session files.
+    let home = TempDir::new().unwrap();
+
+    // 2. Unique marker we'll look for in the session log.
+    let marker = format!("integration-test-{}", Uuid::new_v4());
+    let prompt = format!("echo {marker}");
+
+    // 3. Use the same offline SSE fixture as responses_api_stream_cli so the test is hermetic.
+    let fixture =
+        std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("tests/cli_responses_fixture.sse");
+
+    // 4. Run the codex CLI through cargo (ensures the right bin is built) and invoke `exec`,
+    //    which is what records a session.
+    let mut cmd = AssertCommand::new("cargo");
+    cmd.arg("run")
+        .arg("-p")
+        .arg("codex-cli")
+        .arg("--quiet")
+        .arg("--")
+        .arg("exec")
+        .arg("--skip-git-repo-check")
+        .arg("-C")
+        .arg(env!("CARGO_MANIFEST_DIR"))
+        .arg(&prompt);
+    cmd.env("CODEX_HOME", home.path())
+        .env("OPENAI_API_KEY", "dummy")
+        .env("CODEX_RS_SSE_FIXTURE", &fixture)
+        // Required for CLI arg parsing even though fixture short-circuits network usage.
+        .env("OPENAI_BASE_URL", "http://unused.local");
+
+    let output = cmd.output().unwrap();
+    assert!(
+        output.status.success(),
+        "codex-cli exec failed: {}",
+        String::from_utf8_lossy(&output.stderr)
+    );
+
+    // 5. Sessions are written asynchronously; wait briefly for the directory to appear.
+    let sessions_dir = home.path().join("sessions");
+    let start = Instant::now();
+    while !sessions_dir.exists() && start.elapsed() < Duration::from_secs(2) {
+        std::thread::sleep(Duration::from_millis(50));
+    }
+
+    // 6. Scan all session files and find the one that contains our marker.
+    let mut matching_files = vec![];
+    for entry in WalkDir::new(&sessions_dir) {
+        let entry = entry.unwrap();
+        if entry.file_type().is_file() && entry.file_name().to_string_lossy().ends_with(".jsonl") {
+            let path = entry.path();
+            let content = std::fs::read_to_string(path).unwrap();
+            let mut lines = content.lines();
+            // Skip SessionMeta (first line)
+            let _ = lines.next();
+            for line in lines {
+                let item: Value = serde_json::from_str(line).unwrap();
+                if let Some("message") = item.get("type").and_then(|t| t.as_str()) {
+                    if let Some(content) = item.get("content") {
+                        if content.to_string().contains(&marker) {
+                            matching_files.push(path.to_owned());
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+    }
+    assert_eq!(
+        matching_files.len(),
+        1,
+        "Expected exactly one session file containing the marker, found {}",
+        matching_files.len()
+    );
+    let path = &matching_files[0];
+
+    // 7. Verify directory structure: sessions/YYYY/MM/DD/filename.jsonl
+    let rel = match path.strip_prefix(&sessions_dir) {
+        Ok(r) => r,
+        Err(_) => panic!("session file should live under sessions/"),
+    };
+    let comps: Vec<String> = rel
+        .components()
+        .map(|c| c.as_os_str().to_string_lossy().into_owned())
+        .collect();
+    assert_eq!(
+        comps.len(),
+        4,
+        "Expected sessions/YYYY/MM/DD/<file>, got {rel:?}"
+    );
+    let year = &comps[0];
+    let month = &comps[1];
+    let day = &comps[2];
+    assert!(
+        year.len() == 4 && year.chars().all(|c| c.is_ascii_digit()),
+        "Year dir not 4-digit numeric: {year}"
+    );
+    assert!(
+        month.len() == 2 && month.chars().all(|c| c.is_ascii_digit()),
+        "Month dir not zero-padded 2-digit numeric: {month}"
+    );
+    assert!(
+        day.len() == 2 && day.chars().all(|c| c.is_ascii_digit()),
+        "Day dir not zero-padded 2-digit numeric: {day}"
+    );
+    // Range checks (best-effort; won't fail on leading zeros)
+    if let Ok(m) = month.parse::<u8>() {
+        assert!((1..=12).contains(&m), "Month out of range: {m}");
+    }
+    if let Ok(d) = day.parse::<u8>() {
+        assert!((1..=31).contains(&d), "Day out of range: {d}");
+    }
+
+    // 8. Parse SessionMeta line and basic sanity checks.
+    let content = std::fs::read_to_string(path).unwrap();
+    let mut lines = content.lines();
+    let meta: Value = serde_json::from_str(lines.next().unwrap()).unwrap();
+    assert!(meta.get("id").is_some(), "SessionMeta missing id");
+    assert!(
+        meta.get("timestamp").is_some(),
+        "SessionMeta missing timestamp"
+    );
+
+    // 9. Confirm at least one message contains the marker.
+    let mut found_message = false;
+    for line in lines {
+        let item: Value = serde_json::from_str(line).unwrap();
+        if item.get("type").map(|t| t == "message").unwrap_or(false) {
+            if let Some(content) = item.get("content") {
+                if content.to_string().contains(&marker) {
+                    found_message = true;
+                    break;
+                }
+            }
+        }
+    }
+    assert!(
+        found_message,
+        "No message found in session file containing the marker"
+    );
+}

codex-rs/core/tests/stream_no_completed.rs

@@ -32,6 +32,8 @@ fn sse_completed(id: &str) -> String {
 }
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+// this test is flaky (has race conditions), so we ignore it for now
+#[ignore]
 async fn retries_on_early_close() {
     #![allow(clippy::unwrap_used)]
 

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

@@ -1,492 +1,37 @@
-use codex_common::elapsed::format_elapsed;
 use codex_common::summarize_sandbox_policy;
 use codex_core::WireApi;
 use codex_core::config::Config;
 use codex_core::model_supports_reasoning_summaries;
-use codex_core::protocol::AgentMessageEvent;
-use codex_core::protocol::BackgroundEventEvent;
-use codex_core::protocol::ErrorEvent;
 use codex_core::protocol::Event;
-use codex_core::protocol::EventMsg;
-use codex_core::protocol::ExecCommandBeginEvent;
-use codex_core::protocol::ExecCommandEndEvent;
-use codex_core::protocol::FileChange;
-use codex_core::protocol::McpToolCallBeginEvent;
-use codex_core::protocol::McpToolCallEndEvent;
-use codex_core::protocol::PatchApplyBeginEvent;
-use codex_core::protocol::PatchApplyEndEvent;
-use codex_core::protocol::SessionConfiguredEvent;
-use codex_core::protocol::TokenUsage;
-use owo_colors::OwoColorize;
-use owo_colors::Style;
-use shlex::try_join;
-use std::collections::HashMap;
-use std::time::Instant;
 
-/// This should be configurable. When used in CI, users may not want to impose
-/// a limit so they can see the full transcript.
-const MAX_OUTPUT_LINES_FOR_EXEC_TOOL_CALL: usize = 20;
+pub(crate) trait EventProcessor {
+    /// Print summary of effective configuration and user prompt.
+    fn print_config_summary(&mut self, config: &Config, prompt: &str);
 
-pub(crate) struct EventProcessor {
-    call_id_to_command: HashMap<String, ExecCommandBegin>,
-    call_id_to_patch: HashMap<String, PatchApplyBegin>,
-
-    /// Tracks in-flight MCP tool calls so we can calculate duration and print
-    /// a concise summary when the corresponding `McpToolCallEnd` event is
-    /// received.
-    call_id_to_tool_call: HashMap<String, McpToolCallBegin>,
-
-    // To ensure that --color=never is respected, ANSI escapes _must_ be added
-    // using .style() with one of these fields. If you need a new style, add a
-    // new field here.
-    bold: Style,
-    italic: Style,
-    dimmed: Style,
-
-    magenta: Style,
-    red: Style,
-    green: Style,
-    cyan: Style,
-
-    /// Whether to include `AgentReasoning` events in the output.
-    show_agent_reasoning: bool,
+    /// Handle a single event emitted by the agent.
+    fn process_event(&mut self, event: Event);
 }
 
-impl EventProcessor {
-    pub(crate) fn create_with_ansi(with_ansi: bool, show_agent_reasoning: bool) -> Self {
-        let call_id_to_command = HashMap::new();
-        let call_id_to_patch = HashMap::new();
-        let call_id_to_tool_call = HashMap::new();
-
-        if with_ansi {
-            Self {
-                call_id_to_command,
-                call_id_to_patch,
-                bold: Style::new().bold(),
-                italic: Style::new().italic(),
-                dimmed: Style::new().dimmed(),
-                magenta: Style::new().magenta(),
-                red: Style::new().red(),
-                green: Style::new().green(),
-                cyan: Style::new().cyan(),
-                call_id_to_tool_call,
-                show_agent_reasoning,
-            }
-        } else {
-            Self {
-                call_id_to_command,
-                call_id_to_patch,
-                bold: Style::new(),
-                italic: Style::new(),
-                dimmed: Style::new(),
-                magenta: Style::new(),
-                red: Style::new(),
-                green: Style::new(),
-                cyan: Style::new(),
-                call_id_to_tool_call,
-                show_agent_reasoning,
-            }
-        }
-    }
-}
-
-struct ExecCommandBegin {
-    command: Vec<String>,
-    start_time: Instant,
-}
-
-/// Metadata captured when an `McpToolCallBegin` event is received.
-struct McpToolCallBegin {
-    /// Formatted invocation string, e.g. `server.tool({"city":"sf"})`.
-    invocation: String,
-    /// Timestamp when the call started so we can compute duration later.
-    start_time: Instant,
-}
-
-struct PatchApplyBegin {
-    start_time: Instant,
-    auto_approved: bool,
-}
-
-// Timestamped println helper. The timestamp is styled with self.dimmed.
-#[macro_export]
-macro_rules! ts_println {
-    ($self:ident, $($arg:tt)*) => {{
-        let now = chrono::Utc::now();
-        let formatted = now.format("[%Y-%m-%dT%H:%M:%S]");
-        print!("{} ", formatted.style($self.dimmed));
-        println!($($arg)*);
-    }};
-}
-
-impl EventProcessor {
-    /// 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) {
-        const VERSION: &str = env!("CARGO_PKG_VERSION");
-        ts_println!(
-            self,
-            "OpenAI Codex v{} (research preview)\n--------",
-            VERSION
-        );
-
-        let mut entries = vec![
-            ("workdir", config.cwd.display().to_string()),
-            ("model", config.model.clone()),
-            ("provider", config.model_provider_id.clone()),
-            ("approval", format!("{:?}", config.approval_policy)),
-            ("sandbox", summarize_sandbox_policy(&config.sandbox_policy)),
-        ];
-        if config.model_provider.wire_api == WireApi::Responses
-            && model_supports_reasoning_summaries(config)
-        {
-            entries.push((
-                "reasoning effort",
-                config.model_reasoning_effort.to_string(),
-            ));
-            entries.push((
-                "reasoning summaries",
-                config.model_reasoning_summary.to_string(),
-            ));
-        }
-
-        for (key, value) in entries {
-            println!("{} {}", format!("{key}:").style(self.bold), value);
-        }
-
-        println!("--------");
-
-        // Echo the prompt that will be sent to the agent so it is visible in the
-        // transcript/logs before any events come in. Note the prompt may have been
-        // read from stdin, so it may not be visible in the terminal otherwise.
-        ts_println!(
-            self,
-            "{}\n{}",
-            "User instructions:".style(self.bold).style(self.cyan),
-            prompt
-        );
+pub(crate) fn create_config_summary_entries(config: &Config) -> Vec<(&'static str, String)> {
+    let mut entries = vec![
+        ("workdir", config.cwd.display().to_string()),
+        ("model", config.model.clone()),
+        ("provider", config.model_provider_id.clone()),
+        ("approval", format!("{:?}", config.approval_policy)),
+        ("sandbox", summarize_sandbox_policy(&config.sandbox_policy)),
+    ];
+    if config.model_provider.wire_api == WireApi::Responses
+        && model_supports_reasoning_summaries(config)
+    {
+        entries.push((
+            "reasoning effort",
+            config.model_reasoning_effort.to_string(),
+        ));
+        entries.push((
+            "reasoning summaries",
+            config.model_reasoning_summary.to_string(),
+        ));
     }
 
-    pub(crate) fn process_event(&mut self, event: Event) {
-        let Event { id: _, msg } = event;
-        match msg {
-            EventMsg::Error(ErrorEvent { message }) => {
-                let prefix = "ERROR:".style(self.red);
-                ts_println!(self, "{prefix} {message}");
-            }
-            EventMsg::BackgroundEvent(BackgroundEventEvent { message }) => {
-                ts_println!(self, "{}", message.style(self.dimmed));
-            }
-            EventMsg::TaskStarted | EventMsg::TaskComplete(_) => {
-                // Ignore.
-            }
-            EventMsg::TokenCount(TokenUsage { total_tokens, .. }) => {
-                ts_println!(self, "tokens used: {total_tokens}");
-            }
-            EventMsg::AgentMessage(AgentMessageEvent { message }) => {
-                ts_println!(
-                    self,
-                    "{}\n{message}",
-                    "codex".style(self.bold).style(self.magenta)
-                );
-            }
-            EventMsg::ExecCommandBegin(ExecCommandBeginEvent {
-                call_id,
-                command,
-                cwd,
-            }) => {
-                self.call_id_to_command.insert(
-                    call_id.clone(),
-                    ExecCommandBegin {
-                        command: command.clone(),
-                        start_time: Instant::now(),
-                    },
-                );
-                ts_println!(
-                    self,
-                    "{} {} in {}",
-                    "exec".style(self.magenta),
-                    escape_command(&command).style(self.bold),
-                    cwd.to_string_lossy(),
-                );
-            }
-            EventMsg::ExecCommandEnd(ExecCommandEndEvent {
-                call_id,
-                stdout,
-                stderr,
-                exit_code,
-            }) => {
-                let exec_command = self.call_id_to_command.remove(&call_id);
-                let (duration, call) = if let Some(ExecCommandBegin {
-                    command,
-                    start_time,
-                }) = exec_command
-                {
-                    (
-                        format!(" in {}", format_elapsed(start_time)),
-                        format!("{}", escape_command(&command).style(self.bold)),
-                    )
-                } else {
-                    ("".to_string(), format!("exec('{call_id}')"))
-                };
-
-                let output = if exit_code == 0 { stdout } else { stderr };
-                let truncated_output = output
-                    .lines()
-                    .take(MAX_OUTPUT_LINES_FOR_EXEC_TOOL_CALL)
-                    .collect::<Vec<_>>()
-                    .join("\n");
-                match exit_code {
-                    0 => {
-                        let title = format!("{call} succeeded{duration}:");
-                        ts_println!(self, "{}", title.style(self.green));
-                    }
-                    _ => {
-                        let title = format!("{call} exited {exit_code}{duration}:");
-                        ts_println!(self, "{}", title.style(self.red));
-                    }
-                }
-                println!("{}", truncated_output.style(self.dimmed));
-            }
-            EventMsg::McpToolCallBegin(McpToolCallBeginEvent {
-                call_id,
-                server,
-                tool,
-                arguments,
-            }) => {
-                // Build fully-qualified tool name: server.tool
-                let fq_tool_name = format!("{server}.{tool}");
-
-                // Format arguments as compact JSON so they fit on one line.
-                let args_str = arguments
-                    .as_ref()
-                    .map(|v: &serde_json::Value| {
-                        serde_json::to_string(v).unwrap_or_else(|_| v.to_string())
-                    })
-                    .unwrap_or_default();
-
-                let invocation = if args_str.is_empty() {
-                    format!("{fq_tool_name}()")
-                } else {
-                    format!("{fq_tool_name}({args_str})")
-                };
-
-                self.call_id_to_tool_call.insert(
-                    call_id.clone(),
-                    McpToolCallBegin {
-                        invocation: invocation.clone(),
-                        start_time: Instant::now(),
-                    },
-                );
-
-                ts_println!(
-                    self,
-                    "{} {}",
-                    "tool".style(self.magenta),
-                    invocation.style(self.bold),
-                );
-            }
-            EventMsg::McpToolCallEnd(tool_call_end_event) => {
-                let is_success = tool_call_end_event.is_success();
-                let McpToolCallEndEvent { call_id, result } = tool_call_end_event;
-                // Retrieve start time and invocation for duration calculation and labeling.
-                let info = self.call_id_to_tool_call.remove(&call_id);
-
-                let (duration, invocation) = if let Some(McpToolCallBegin {
-                    invocation,
-                    start_time,
-                    ..
-                }) = info
-                {
-                    (format!(" in {}", format_elapsed(start_time)), invocation)
-                } else {
-                    (String::new(), format!("tool('{call_id}')"))
-                };
-
-                let status_str = if is_success { "success" } else { "failed" };
-                let title_style = if is_success { self.green } else { self.red };
-                let title = format!("{invocation} {status_str}{duration}:");
-
-                ts_println!(self, "{}", title.style(title_style));
-
-                if let Ok(res) = result {
-                    let val: serde_json::Value = res.into();
-                    let pretty =
-                        serde_json::to_string_pretty(&val).unwrap_or_else(|_| val.to_string());
-
-                    for line in pretty.lines().take(MAX_OUTPUT_LINES_FOR_EXEC_TOOL_CALL) {
-                        println!("{}", line.style(self.dimmed));
-                    }
-                }
-            }
-            EventMsg::PatchApplyBegin(PatchApplyBeginEvent {
-                call_id,
-                auto_approved,
-                changes,
-            }) => {
-                // Store metadata so we can calculate duration later when we
-                // receive the corresponding PatchApplyEnd event.
-                self.call_id_to_patch.insert(
-                    call_id.clone(),
-                    PatchApplyBegin {
-                        start_time: Instant::now(),
-                        auto_approved,
-                    },
-                );
-
-                ts_println!(
-                    self,
-                    "{} auto_approved={}:",
-                    "apply_patch".style(self.magenta),
-                    auto_approved,
-                );
-
-                // Pretty-print the patch summary with colored diff markers so
-                // it’s easy to scan in the terminal output.
-                for (path, change) in changes.iter() {
-                    match change {
-                        FileChange::Add { content } => {
-                            let header = format!(
-                                "{} {}",
-                                format_file_change(change),
-                                path.to_string_lossy()
-                            );
-                            println!("{}", header.style(self.magenta));
-                            for line in content.lines() {
-                                println!("{}", line.style(self.green));
-                            }
-                        }
-                        FileChange::Delete => {
-                            let header = format!(
-                                "{} {}",
-                                format_file_change(change),
-                                path.to_string_lossy()
-                            );
-                            println!("{}", header.style(self.magenta));
-                        }
-                        FileChange::Update {
-                            unified_diff,
-                            move_path,
-                        } => {
-                            let header = if let Some(dest) = move_path {
-                                format!(
-                                    "{} {} -> {}",
-                                    format_file_change(change),
-                                    path.to_string_lossy(),
-                                    dest.to_string_lossy()
-                                )
-                            } else {
-                                format!("{} {}", format_file_change(change), path.to_string_lossy())
-                            };
-                            println!("{}", header.style(self.magenta));
-
-                            // Colorize diff lines. We keep file header lines
-                            // (--- / +++) without extra coloring so they are
-                            // still readable.
-                            for diff_line in unified_diff.lines() {
-                                if diff_line.starts_with('+') && !diff_line.starts_with("+++") {
-                                    println!("{}", diff_line.style(self.green));
-                                } else if diff_line.starts_with('-')
-                                    && !diff_line.starts_with("---")
-                                {
-                                    println!("{}", diff_line.style(self.red));
-                                } else {
-                                    println!("{diff_line}");
-                                }
-                            }
-                        }
-                    }
-                }
-            }
-            EventMsg::PatchApplyEnd(PatchApplyEndEvent {
-                call_id,
-                stdout,
-                stderr,
-                success,
-            }) => {
-                let patch_begin = self.call_id_to_patch.remove(&call_id);
-
-                // Compute duration and summary label similar to exec commands.
-                let (duration, label) = if let Some(PatchApplyBegin {
-                    start_time,
-                    auto_approved,
-                }) = patch_begin
-                {
-                    (
-                        format!(" in {}", format_elapsed(start_time)),
-                        format!("apply_patch(auto_approved={auto_approved})"),
-                    )
-                } else {
-                    (String::new(), format!("apply_patch('{call_id}')"))
-                };
-
-                let (exit_code, output, title_style) = if success {
-                    (0, stdout, self.green)
-                } else {
-                    (1, stderr, self.red)
-                };
-
-                let title = format!("{label} exited {exit_code}{duration}:");
-                ts_println!(self, "{}", title.style(title_style));
-                for line in output.lines() {
-                    println!("{}", line.style(self.dimmed));
-                }
-            }
-            EventMsg::ExecApprovalRequest(_) => {
-                // Should we exit?
-            }
-            EventMsg::ApplyPatchApprovalRequest(_) => {
-                // Should we exit?
-            }
-            EventMsg::AgentReasoning(agent_reasoning_event) => {
-                if self.show_agent_reasoning {
-                    ts_println!(
-                        self,
-                        "{}\n{}",
-                        "thinking".style(self.italic).style(self.magenta),
-                        agent_reasoning_event.text
-                    );
-                }
-            }
-            EventMsg::SessionConfigured(session_configured_event) => {
-                let SessionConfiguredEvent {
-                    session_id,
-                    model,
-                    history_log_id: _,
-                    history_entry_count: _,
-                } = session_configured_event;
-
-                ts_println!(
-                    self,
-                    "{} {}",
-                    "codex session".style(self.magenta).style(self.bold),
-                    session_id.to_string().style(self.dimmed)
-                );
-
-                ts_println!(self, "model: {}", model);
-                println!();
-            }
-            EventMsg::GetHistoryEntryResponse(_) => {
-                // Currently ignored in exec output.
-            }
-        }
-    }
-}
-
-fn escape_command(command: &[String]) -> String {
-    try_join(command.iter().map(|s| s.as_str())).unwrap_or_else(|_| command.join(" "))
-}
-
-fn format_file_change(change: &FileChange) -> &'static str {
-    match change {
-        FileChange::Add { .. } => "A",
-        FileChange::Delete => "D",
-        FileChange::Update {
-            move_path: Some(_), ..
-        } => "R",
-        FileChange::Update {
-            move_path: None, ..
-        } => "M",
-    }
+    entries
 }

codex-rs/exec/src/event_processor_with_human_output.rs

@@ -0,0 +1,520 @@
+use codex_common::elapsed::format_elapsed;
+use codex_core::config::Config;
+use codex_core::protocol::AgentMessageDeltaEvent;
+use codex_core::protocol::AgentMessageEvent;
+use codex_core::protocol::AgentReasoningDeltaEvent;
+use codex_core::protocol::BackgroundEventEvent;
+use codex_core::protocol::ErrorEvent;
+use codex_core::protocol::Event;
+use codex_core::protocol::EventMsg;
+use codex_core::protocol::ExecCommandBeginEvent;
+use codex_core::protocol::ExecCommandEndEvent;
+use codex_core::protocol::FileChange;
+use codex_core::protocol::McpToolCallBeginEvent;
+use codex_core::protocol::McpToolCallEndEvent;
+use codex_core::protocol::PatchApplyBeginEvent;
+use codex_core::protocol::PatchApplyEndEvent;
+use codex_core::protocol::SessionConfiguredEvent;
+use codex_core::protocol::TokenUsage;
+use owo_colors::OwoColorize;
+use owo_colors::Style;
+use shlex::try_join;
+use std::collections::HashMap;
+use std::io::Write;
+use std::time::Instant;
+
+use crate::event_processor::EventProcessor;
+use crate::event_processor::create_config_summary_entries;
+
+/// This should be configurable. When used in CI, users may not want to impose
+/// a limit so they can see the full transcript.
+const MAX_OUTPUT_LINES_FOR_EXEC_TOOL_CALL: usize = 20;
+pub(crate) struct EventProcessorWithHumanOutput {
+    call_id_to_command: HashMap<String, ExecCommandBegin>,
+    call_id_to_patch: HashMap<String, PatchApplyBegin>,
+
+    /// Tracks in-flight MCP tool calls so we can calculate duration and print
+    /// a concise summary when the corresponding `McpToolCallEnd` event is
+    /// received.
+    call_id_to_tool_call: HashMap<String, McpToolCallBegin>,
+
+    // To ensure that --color=never is respected, ANSI escapes _must_ be added
+    // using .style() with one of these fields. If you need a new style, add a
+    // new field here.
+    bold: Style,
+    italic: Style,
+    dimmed: Style,
+
+    magenta: Style,
+    red: Style,
+    green: Style,
+    cyan: Style,
+
+    /// Whether to include `AgentReasoning` events in the output.
+    show_agent_reasoning: bool,
+    answer_started: bool,
+    reasoning_started: bool,
+}
+
+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();
+        let call_id_to_tool_call = HashMap::new();
+
+        if with_ansi {
+            Self {
+                call_id_to_command,
+                call_id_to_patch,
+                bold: Style::new().bold(),
+                italic: Style::new().italic(),
+                dimmed: Style::new().dimmed(),
+                magenta: Style::new().magenta(),
+                red: Style::new().red(),
+                green: Style::new().green(),
+                cyan: Style::new().cyan(),
+                call_id_to_tool_call,
+                show_agent_reasoning: !config.hide_agent_reasoning,
+                answer_started: false,
+                reasoning_started: false,
+            }
+        } else {
+            Self {
+                call_id_to_command,
+                call_id_to_patch,
+                bold: Style::new(),
+                italic: Style::new(),
+                dimmed: Style::new(),
+                magenta: Style::new(),
+                red: Style::new(),
+                green: Style::new(),
+                cyan: Style::new(),
+                call_id_to_tool_call,
+                show_agent_reasoning: !config.hide_agent_reasoning,
+                answer_started: false,
+                reasoning_started: false,
+            }
+        }
+    }
+}
+
+struct ExecCommandBegin {
+    command: Vec<String>,
+    start_time: Instant,
+}
+
+/// Metadata captured when an `McpToolCallBegin` event is received.
+struct McpToolCallBegin {
+    /// Formatted invocation string, e.g. `server.tool({"city":"sf"})`.
+    invocation: String,
+    /// Timestamp when the call started so we can compute duration later.
+    start_time: Instant,
+}
+
+struct PatchApplyBegin {
+    start_time: Instant,
+    auto_approved: bool,
+}
+
+// Timestamped println helper. The timestamp is styled with self.dimmed.
+#[macro_export]
+macro_rules! ts_println {
+    ($self:ident, $($arg:tt)*) => {{
+        let now = chrono::Utc::now();
+        let formatted = now.format("[%Y-%m-%dT%H:%M:%S]");
+        print!("{} ", formatted.style($self.dimmed));
+        println!($($arg)*);
+    }};
+}
+
+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.
+    fn print_config_summary(&mut self, config: &Config, prompt: &str) {
+        const VERSION: &str = env!("CARGO_PKG_VERSION");
+        ts_println!(
+            self,
+            "OpenAI Codex v{} (research preview)\n--------",
+            VERSION
+        );
+
+        let entries = create_config_summary_entries(config);
+
+        for (key, value) in entries {
+            println!("{} {}", format!("{key}:").style(self.bold), value);
+        }
+
+        println!("--------");
+
+        // Echo the prompt that will be sent to the agent so it is visible in the
+        // transcript/logs before any events come in. Note the prompt may have been
+        // read from stdin, so it may not be visible in the terminal otherwise.
+        ts_println!(
+            self,
+            "{}\n{}",
+            "User instructions:".style(self.bold).style(self.cyan),
+            prompt
+        );
+    }
+
+    fn process_event(&mut self, event: Event) {
+        let Event { id: _, msg } = event;
+        match msg {
+            EventMsg::Error(ErrorEvent { message }) => {
+                let prefix = "ERROR:".style(self.red);
+                ts_println!(self, "{prefix} {message}");
+            }
+            EventMsg::BackgroundEvent(BackgroundEventEvent { message }) => {
+                ts_println!(self, "{}", message.style(self.dimmed));
+            }
+            EventMsg::TaskStarted | EventMsg::TaskComplete(_) => {
+                // Ignore.
+            }
+            EventMsg::TokenCount(TokenUsage { total_tokens, .. }) => {
+                ts_println!(self, "tokens used: {total_tokens}");
+            }
+            EventMsg::AgentMessageDelta(AgentMessageDeltaEvent { delta }) => {
+                if !self.answer_started {
+                    ts_println!(self, "{}\n", "codex".style(self.italic).style(self.magenta));
+                    self.answer_started = true;
+                }
+                print!("{delta}");
+                #[allow(clippy::expect_used)]
+                std::io::stdout().flush().expect("could not flush stdout");
+            }
+            EventMsg::AgentReasoningDelta(AgentReasoningDeltaEvent { delta }) => {
+                if !self.show_agent_reasoning {
+                    return;
+                }
+                if !self.reasoning_started {
+                    ts_println!(
+                        self,
+                        "{}\n",
+                        "thinking".style(self.italic).style(self.magenta),
+                    );
+                    self.reasoning_started = true;
+                }
+                print!("{delta}");
+                #[allow(clippy::expect_used)]
+                std::io::stdout().flush().expect("could not flush stdout");
+            }
+            EventMsg::AgentMessage(AgentMessageEvent { message }) => {
+                // if answer_started is false, this means we haven't received any
+                // delta. Thus, we need to print the message as a new answer.
+                if !self.answer_started {
+                    ts_println!(
+                        self,
+                        "{}\n{}",
+                        "codex".style(self.italic).style(self.magenta),
+                        message,
+                    );
+                } else {
+                    println!();
+                    self.answer_started = false;
+                }
+            }
+            EventMsg::ExecCommandBegin(ExecCommandBeginEvent {
+                call_id,
+                command,
+                cwd,
+            }) => {
+                self.call_id_to_command.insert(
+                    call_id.clone(),
+                    ExecCommandBegin {
+                        command: command.clone(),
+                        start_time: Instant::now(),
+                    },
+                );
+                ts_println!(
+                    self,
+                    "{} {} in {}",
+                    "exec".style(self.magenta),
+                    escape_command(&command).style(self.bold),
+                    cwd.to_string_lossy(),
+                );
+            }
+            EventMsg::ExecCommandEnd(ExecCommandEndEvent {
+                call_id,
+                stdout,
+                stderr,
+                exit_code,
+            }) => {
+                let exec_command = self.call_id_to_command.remove(&call_id);
+                let (duration, call) = if let Some(ExecCommandBegin {
+                    command,
+                    start_time,
+                }) = exec_command
+                {
+                    (
+                        format!(" in {}", format_elapsed(start_time)),
+                        format!("{}", escape_command(&command).style(self.bold)),
+                    )
+                } else {
+                    ("".to_string(), format!("exec('{call_id}')"))
+                };
+
+                let output = if exit_code == 0 { stdout } else { stderr };
+                let truncated_output = output
+                    .lines()
+                    .take(MAX_OUTPUT_LINES_FOR_EXEC_TOOL_CALL)
+                    .collect::<Vec<_>>()
+                    .join("\n");
+                match exit_code {
+                    0 => {
+                        let title = format!("{call} succeeded{duration}:");
+                        ts_println!(self, "{}", title.style(self.green));
+                    }
+                    _ => {
+                        let title = format!("{call} exited {exit_code}{duration}:");
+                        ts_println!(self, "{}", title.style(self.red));
+                    }
+                }
+                println!("{}", truncated_output.style(self.dimmed));
+            }
+            EventMsg::McpToolCallBegin(McpToolCallBeginEvent {
+                call_id,
+                server,
+                tool,
+                arguments,
+            }) => {
+                // Build fully-qualified tool name: server.tool
+                let fq_tool_name = format!("{server}.{tool}");
+
+                // Format arguments as compact JSON so they fit on one line.
+                let args_str = arguments
+                    .as_ref()
+                    .map(|v: &serde_json::Value| {
+                        serde_json::to_string(v).unwrap_or_else(|_| v.to_string())
+                    })
+                    .unwrap_or_default();
+
+                let invocation = if args_str.is_empty() {
+                    format!("{fq_tool_name}()")
+                } else {
+                    format!("{fq_tool_name}({args_str})")
+                };
+
+                self.call_id_to_tool_call.insert(
+                    call_id.clone(),
+                    McpToolCallBegin {
+                        invocation: invocation.clone(),
+                        start_time: Instant::now(),
+                    },
+                );
+
+                ts_println!(
+                    self,
+                    "{} {}",
+                    "tool".style(self.magenta),
+                    invocation.style(self.bold),
+                );
+            }
+            EventMsg::McpToolCallEnd(tool_call_end_event) => {
+                let is_success = tool_call_end_event.is_success();
+                let McpToolCallEndEvent { call_id, result } = tool_call_end_event;
+                // Retrieve start time and invocation for duration calculation and labeling.
+                let info = self.call_id_to_tool_call.remove(&call_id);
+
+                let (duration, invocation) = if let Some(McpToolCallBegin {
+                    invocation,
+                    start_time,
+                    ..
+                }) = info
+                {
+                    (format!(" in {}", format_elapsed(start_time)), invocation)
+                } else {
+                    (String::new(), format!("tool('{call_id}')"))
+                };
+
+                let status_str = if is_success { "success" } else { "failed" };
+                let title_style = if is_success { self.green } else { self.red };
+                let title = format!("{invocation} {status_str}{duration}:");
+
+                ts_println!(self, "{}", title.style(title_style));
+
+                if let Ok(res) = result {
+                    let val: serde_json::Value = res.into();
+                    let pretty =
+                        serde_json::to_string_pretty(&val).unwrap_or_else(|_| val.to_string());
+
+                    for line in pretty.lines().take(MAX_OUTPUT_LINES_FOR_EXEC_TOOL_CALL) {
+                        println!("{}", line.style(self.dimmed));
+                    }
+                }
+            }
+            EventMsg::PatchApplyBegin(PatchApplyBeginEvent {
+                call_id,
+                auto_approved,
+                changes,
+            }) => {
+                // Store metadata so we can calculate duration later when we
+                // receive the corresponding PatchApplyEnd event.
+                self.call_id_to_patch.insert(
+                    call_id.clone(),
+                    PatchApplyBegin {
+                        start_time: Instant::now(),
+                        auto_approved,
+                    },
+                );
+
+                ts_println!(
+                    self,
+                    "{} auto_approved={}:",
+                    "apply_patch".style(self.magenta),
+                    auto_approved,
+                );
+
+                // Pretty-print the patch summary with colored diff markers so
+                // it's easy to scan in the terminal output.
+                for (path, change) in changes.iter() {
+                    match change {
+                        FileChange::Add { content } => {
+                            let header = format!(
+                                "{} {}",
+                                format_file_change(change),
+                                path.to_string_lossy()
+                            );
+                            println!("{}", header.style(self.magenta));
+                            for line in content.lines() {
+                                println!("{}", line.style(self.green));
+                            }
+                        }
+                        FileChange::Delete => {
+                            let header = format!(
+                                "{} {}",
+                                format_file_change(change),
+                                path.to_string_lossy()
+                            );
+                            println!("{}", header.style(self.magenta));
+                        }
+                        FileChange::Update {
+                            unified_diff,
+                            move_path,
+                        } => {
+                            let header = if let Some(dest) = move_path {
+                                format!(
+                                    "{} {} -> {}",
+                                    format_file_change(change),
+                                    path.to_string_lossy(),
+                                    dest.to_string_lossy()
+                                )
+                            } else {
+                                format!("{} {}", format_file_change(change), path.to_string_lossy())
+                            };
+                            println!("{}", header.style(self.magenta));
+
+                            // Colorize diff lines. We keep file header lines
+                            // (--- / +++) without extra coloring so they are
+                            // still readable.
+                            for diff_line in unified_diff.lines() {
+                                if diff_line.starts_with('+') && !diff_line.starts_with("+++") {
+                                    println!("{}", diff_line.style(self.green));
+                                } else if diff_line.starts_with('-')
+                                    && !diff_line.starts_with("---")
+                                {
+                                    println!("{}", diff_line.style(self.red));
+                                } else {
+                                    println!("{diff_line}");
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            EventMsg::PatchApplyEnd(PatchApplyEndEvent {
+                call_id,
+                stdout,
+                stderr,
+                success,
+            }) => {
+                let patch_begin = self.call_id_to_patch.remove(&call_id);
+
+                // Compute duration and summary label similar to exec commands.
+                let (duration, label) = if let Some(PatchApplyBegin {
+                    start_time,
+                    auto_approved,
+                }) = patch_begin
+                {
+                    (
+                        format!(" in {}", format_elapsed(start_time)),
+                        format!("apply_patch(auto_approved={auto_approved})"),
+                    )
+                } else {
+                    (String::new(), format!("apply_patch('{call_id}')"))
+                };
+
+                let (exit_code, output, title_style) = if success {
+                    (0, stdout, self.green)
+                } else {
+                    (1, stderr, self.red)
+                };
+
+                let title = format!("{label} exited {exit_code}{duration}:");
+                ts_println!(self, "{}", title.style(title_style));
+                for line in output.lines() {
+                    println!("{}", line.style(self.dimmed));
+                }
+            }
+            EventMsg::ExecApprovalRequest(_) => {
+                // Should we exit?
+            }
+            EventMsg::ApplyPatchApprovalRequest(_) => {
+                // Should we exit?
+            }
+            EventMsg::AgentReasoning(agent_reasoning_event) => {
+                if self.show_agent_reasoning {
+                    if !self.reasoning_started {
+                        ts_println!(
+                            self,
+                            "{}\n{}",
+                            "codex".style(self.italic).style(self.magenta),
+                            agent_reasoning_event.text,
+                        );
+                    } else {
+                        println!();
+                        self.reasoning_started = false;
+                    }
+                }
+            }
+            EventMsg::SessionConfigured(session_configured_event) => {
+                let SessionConfiguredEvent {
+                    session_id,
+                    model,
+                    history_log_id: _,
+                    history_entry_count: _,
+                } = session_configured_event;
+
+                ts_println!(
+                    self,
+                    "{} {}",
+                    "codex session".style(self.magenta).style(self.bold),
+                    session_id.to_string().style(self.dimmed)
+                );
+
+                ts_println!(self, "model: {}", model);
+                println!();
+            }
+            EventMsg::GetHistoryEntryResponse(_) => {
+                // Currently ignored in exec output.
+            }
+        }
+    }
+}
+
+fn escape_command(command: &[String]) -> String {
+    try_join(command.iter().map(|s| s.as_str())).unwrap_or_else(|_| command.join(" "))
+}
+
+fn format_file_change(change: &FileChange) -> &'static str {
+    match change {
+        FileChange::Add { .. } => "A",
+        FileChange::Delete => "D",
+        FileChange::Update {
+            move_path: Some(_), ..
+        } => "R",
+        FileChange::Update {
+            move_path: None, ..
+        } => "M",
+    }
+}

codex-rs/exec/src/event_processor_with_json_output.rs

@@ -0,0 +1,48 @@
+use std::collections::HashMap;
+
+use codex_core::config::Config;
+use codex_core::protocol::Event;
+use codex_core::protocol::EventMsg;
+use serde_json::json;
+
+use crate::event_processor::EventProcessor;
+use crate::event_processor::create_config_summary_entries;
+
+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 entries = create_config_summary_entries(config)
+            .into_iter()
+            .map(|(key, value)| (key.to_string(), value))
+            .collect::<HashMap<String, String>>();
+        #[allow(clippy::expect_used)]
+        let config_json =
+            serde_json::to_string(&entries).expect("Failed to serialize config summary to JSON");
+        println!("{config_json}");
+
+        let prompt_json = json!({
+            "prompt": prompt,
+        });
+        println!("{prompt_json}");
+    }
+
+    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 +1,7 @@
 mod cli;
 mod event_processor;
+mod event_processor_with_human_output;
+mod event_processor_with_json_output;
 
 use std::io::IsTerminal;
 use std::io::Read;
@@ -19,12 +21,15 @@ 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_with_human_output::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 +41,7 @@ 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,
@@ -115,8 +121,15 @@ 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.hide_agent_reasoning);
+    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,
+        ))
+    };
+
     // Print the effective configuration and prompt so users can see what Codex
     // is using.
     event_processor.print_config_summary(&config, &prompt);

codex-rs/justfile

@@ -23,3 +23,10 @@ file-search *args:
 # format code
 fmt:
     cargo fmt -- --config imports_granularity=Item
+
+fix:
+    cargo clippy --fix --all-features --tests --allow-dirty
+
+install:
+    rustup show active-toolchain
+    cargo fetch

codex-rs/mcp-server/src/codex_tool_runner.rs

@@ -171,6 +171,12 @@ pub async fn run_codex_tool_session(
                     EventMsg::SessionConfigured(_) => {
                         tracing::error!("unexpected SessionConfigured event");
                     }
+                    EventMsg::AgentMessageDelta(_) => {
+                        // TODO: think how we want to support this in the MCP
+                    }
+                    EventMsg::AgentReasoningDelta(_) => {
+                        // TODO: think how we want to support this in the MCP
+                    }
                     EventMsg::Error(_)
                     | EventMsg::TaskStarted
                     | EventMsg::TokenCount(_)

codex-rs/rust-toolchain.toml

@@ -0,0 +1,3 @@
+[toolchain]
+channel = "1.88.0"
+components = [ "clippy", "rustfmt", "rust-src"]

codex-rs/tui/src/app.rs

@@ -18,8 +18,22 @@ use crossterm::event::KeyEvent;
 use crossterm::event::MouseEvent;
 use crossterm::event::MouseEventKind;
 use std::path::PathBuf;
+use std::sync::Arc;
+use std::sync::Mutex;
 use std::sync::mpsc::Receiver;
 use std::sync::mpsc::channel;
+use std::thread;
+use std::time::Duration;
+
+/// Debouncing is often a helpful performance optimization, though as shown in
+/// https://github.com/openai/codex/pull/1610, it requires care to ensure that
+/// it works well with interrupts via ctrl-C. For now, we favor correctness at
+/// the cost of performance, but it would be worth revisiting this in the
+/// future.
+const DEBOUNCE_REDRAW_REQUESTS: bool = false;
+
+/// Time window for debouncing redraw requests.
+const REDRAW_DEBOUNCE: Duration = Duration::from_millis(10);
 
 /// Top-level application state: which full-screen view is currently active.
 #[allow(clippy::large_enum_variant)]
@@ -46,6 +60,9 @@ pub(crate) struct App<'a> {
 
     file_search: FileSearchManager,
 
+    /// True when a redraw has been scheduled but not yet executed.
+    pending_redraw: Arc<Mutex<bool>>,
+
     /// Stored parameters needed to instantiate the ChatWidget later, e.g.,
     /// after dismissing the Git-repo warning.
     chat_args: Option<ChatWidgetArgs>,
@@ -60,7 +77,7 @@ struct ChatWidgetArgs {
     initial_images: Vec<PathBuf>,
 }
 
-impl<'a> App<'a> {
+impl App<'_> {
     pub(crate) fn new(
         config: Config,
         initial_prompt: Option<String>,
@@ -70,6 +87,7 @@ impl<'a> App<'a> {
     ) -> Self {
         let (app_event_tx, app_event_rx) = channel();
         let app_event_tx = AppEventSender::new(app_event_tx);
+        let pending_redraw = Arc::new(Mutex::new(false));
         let scroll_event_helper = ScrollEventHelper::new(app_event_tx.clone());
 
         // Spawn a dedicated thread for reading the crossterm event loop and
@@ -83,7 +101,7 @@ impl<'a> App<'a> {
                             app_event_tx.send(AppEvent::KeyEvent(key_event));
                         }
                         crossterm::event::Event::Resize(_, _) => {
-                            app_event_tx.send(AppEvent::Redraw);
+                            app_event_tx.send(AppEvent::RequestRedraw);
                         }
                         crossterm::event::Event::Mouse(MouseEvent {
                             kind: MouseEventKind::ScrollUp,
@@ -152,6 +170,7 @@ impl<'a> App<'a> {
             app_state,
             config,
             file_search,
+            pending_redraw,
             chat_args,
         }
     }
@@ -162,6 +181,29 @@ impl<'a> App<'a> {
         self.app_event_tx.clone()
     }
 
+    /// Schedule a redraw if one is not already pending.
+    #[allow(clippy::unwrap_used)]
+    fn schedule_redraw(&self) {
+        {
+            #[allow(clippy::unwrap_used)]
+            let mut flag = self.pending_redraw.lock().unwrap();
+            if *flag {
+                return;
+            }
+            *flag = true;
+        }
+
+        let tx = self.app_event_tx.clone();
+        let pending_redraw = self.pending_redraw.clone();
+        thread::spawn(move || {
+            thread::sleep(REDRAW_DEBOUNCE);
+            tx.send(AppEvent::Redraw);
+            #[allow(clippy::unwrap_used)]
+            let mut f = pending_redraw.lock().unwrap();
+            *f = false;
+        });
+    }
+
     pub(crate) fn run(
         &mut self,
         terminal: &mut tui::Tui,
@@ -169,12 +211,19 @@ impl<'a> App<'a> {
     ) -> Result<()> {
         // Insert an event to trigger the first render.
         let app_event_tx = self.app_event_tx.clone();
-        app_event_tx.send(AppEvent::Redraw);
+        app_event_tx.send(AppEvent::RequestRedraw);
 
         while let Ok(event) = self.app_event_rx.recv() {
             match event {
+                AppEvent::RequestRedraw => {
+                    if DEBOUNCE_REDRAW_REQUESTS {
+                        self.schedule_redraw();
+                    } else {
+                        self.redraw_immediately(terminal)?;
+                    }
+                }
                 AppEvent::Redraw => {
-                    self.draw_next_frame(terminal)?;
+                    self.redraw_immediately(terminal)?;
                 }
                 AppEvent::KeyEvent(key_event) => {
                     match key_event {
@@ -199,7 +248,21 @@ impl<'a> App<'a> {
                             modifiers: crossterm::event::KeyModifiers::CONTROL,
                             ..
                         } => {
-                            self.app_event_tx.send(AppEvent::ExitRequest);
+                            match &mut self.app_state {
+                                AppState::Chat { widget } => {
+                                    if widget.composer_is_empty() {
+                                        self.app_event_tx.send(AppEvent::ExitRequest);
+                                    } else {
+                                        // Treat Ctrl+D as a normal key event when the composer
+                                        // is not empty so that it doesn't quit the application
+                                        // prematurely.
+                                        self.dispatch_key_event(key_event);
+                                    }
+                                }
+                                AppState::Login { .. } | AppState::GitWarning { .. } => {
+                                    self.app_event_tx.send(AppEvent::ExitRequest);
+                                }
+                            }
                         }
                         _ => {
                             self.dispatch_key_event(key_event);
@@ -235,7 +298,7 @@ impl<'a> App<'a> {
                             Vec::new(),
                         ));
                         self.app_state = AppState::Chat { widget: new_widget };
-                        self.app_event_tx.send(AppEvent::Redraw);
+                        self.app_event_tx.send(AppEvent::RequestRedraw);
                     }
                     SlashCommand::ToggleMouseMode => {
                         if let Err(e) = mouse_capture.toggle() {
@@ -283,6 +346,8 @@ impl<'a> App<'a> {
     }
 
     fn draw_next_frame(&mut self, terminal: &mut tui::Tui) -> Result<()> {
+        // TODO: add a throttle to avoid redrawing too often
+
         match &mut self.app_state {
             AppState::Chat { widget } => {
                 terminal.draw(|frame| frame.render_widget_ref(&**widget, frame.area()))?;
@@ -320,7 +385,7 @@ impl<'a> App<'a> {
                         args.initial_images,
                     ));
                     self.app_state = AppState::Chat { widget };
-                    self.app_event_tx.send(AppEvent::Redraw);
+                    self.app_event_tx.send(AppEvent::RequestRedraw);
                 }
                 GitWarningOutcome::Quit => {
                     self.app_event_tx.send(AppEvent::ExitRequest);
@@ -332,6 +397,10 @@ impl<'a> App<'a> {
         }
     }
 
+    fn redraw_immediately(&mut self, terminal: &mut tui::Tui) -> Result<()> {
+        self.draw_next_frame(terminal)
+    }
+
     fn dispatch_paste_event(&mut self, pasted: String) {
         match &mut self.app_state {
             AppState::Chat { widget } => widget.handle_paste(pasted),

codex-rs/tui/src/app_event.rs

@@ -8,6 +8,10 @@ use crate::slash_command::SlashCommand;
 pub(crate) enum AppEvent {
     CodexEvent(Event),
 
+    /// Request a redraw which will be debounced by the [`App`].
+    RequestRedraw,
+
+    /// Actually draw the next frame.
     Redraw,
 
     KeyEvent(KeyEvent),

codex-rs/tui/src/bottom_pane/chat_composer.rs

@@ -76,6 +76,11 @@ impl ChatComposer<'_> {
         this
     }
 
+    /// Returns true if the composer currently contains no user input.
+    pub(crate) fn is_empty(&self) -> bool {
+        self.textarea.is_empty()
+    }
+
     /// Update the cached *context-left* percentage and refresh the placeholder
     /// text. The UI relies on the placeholder to convey the remaining
     /// context when the composer is empty.

codex-rs/tui/src/bottom_pane/chat_composer_history.rs

@@ -72,8 +72,7 @@ impl ChatComposerHistory {
             return false;
         }
 
-        let lines = textarea.lines();
-        if lines.len() == 1 && lines[0].is_empty() {
+        if textarea.is_empty() {
             return true;
         }
 
@@ -85,6 +84,7 @@ impl ChatComposerHistory {
             return false;
         }
 
+        let lines = textarea.lines();
         matches!(&self.last_history_text, Some(prev) if prev == &lines.join("\n"))
     }
 

codex-rs/tui/src/bottom_pane/mod.rs

@@ -162,6 +162,10 @@ impl BottomPane<'_> {
         }
     }
 
+    pub(crate) fn composer_is_empty(&self) -> bool {
+        self.composer.is_empty()
+    }
+
     pub(crate) fn is_task_running(&self) -> bool {
         self.is_task_running
     }
@@ -208,7 +212,7 @@ impl BottomPane<'_> {
     }
 
     pub(crate) fn request_redraw(&self) {
-        self.app_event_tx.send(AppEvent::Redraw)
+        self.app_event_tx.send(AppEvent::RequestRedraw)
     }
 
     /// Returns true when a popup inside the composer is visible.

codex-rs/tui/src/bottom_pane/status_indicator_view.rs

@@ -24,7 +24,7 @@ impl StatusIndicatorView {
     }
 }
 
-impl<'a> BottomPaneView<'a> for StatusIndicatorView {
+impl BottomPaneView<'_> for StatusIndicatorView {
     fn update_status_text(&mut self, text: String) -> ConditionalUpdate {
         self.update_text(text);
         ConditionalUpdate::NeedsRedraw

codex-rs/tui/src/chatwidget.rs

@@ -3,7 +3,9 @@ use std::sync::Arc;
 
 use codex_core::codex_wrapper::init_codex;
 use codex_core::config::Config;
+use codex_core::protocol::AgentMessageDeltaEvent;
 use codex_core::protocol::AgentMessageEvent;
+use codex_core::protocol::AgentReasoningDeltaEvent;
 use codex_core::protocol::AgentReasoningEvent;
 use codex_core::protocol::ApplyPatchApprovalRequestEvent;
 use codex_core::protocol::ErrorEvent;
@@ -49,6 +51,8 @@ pub(crate) struct ChatWidget<'a> {
     config: Config,
     initial_user_message: Option<UserMessage>,
     token_usage: TokenUsage,
+    reasoning_buffer: String,
+    answer_buffer: String,
 }
 
 #[derive(Clone, Copy, Eq, PartialEq)]
@@ -135,6 +139,8 @@ impl ChatWidget<'_> {
                 initial_images,
             ),
             token_usage: TokenUsage::default(),
+            reasoning_buffer: String::new(),
+            answer_buffer: String::new(),
         }
     }
 
@@ -240,16 +246,51 @@ impl ChatWidget<'_> {
                 self.request_redraw();
             }
             EventMsg::AgentMessage(AgentMessageEvent { message }) => {
+                // if the answer buffer is empty, this means we haven't received any
+                // delta. Thus, we need to print the message as a new answer.
+                if self.answer_buffer.is_empty() {
+                    self.conversation_history
+                        .add_agent_message(&self.config, message);
+                } else {
+                    self.conversation_history
+                        .replace_prev_agent_message(&self.config, message);
+                }
+                self.answer_buffer.clear();
+                self.request_redraw();
+            }
+            EventMsg::AgentMessageDelta(AgentMessageDeltaEvent { delta }) => {
+                if self.answer_buffer.is_empty() {
+                    self.conversation_history
+                        .add_agent_message(&self.config, "".to_string());
+                }
+                self.answer_buffer.push_str(&delta.clone());
                 self.conversation_history
-                    .add_agent_message(&self.config, message);
+                    .replace_prev_agent_message(&self.config, self.answer_buffer.clone());
+                self.request_redraw();
+            }
+            EventMsg::AgentReasoningDelta(AgentReasoningDeltaEvent { delta }) => {
+                if self.reasoning_buffer.is_empty() {
+                    self.conversation_history
+                        .add_agent_reasoning(&self.config, "".to_string());
+                }
+                self.reasoning_buffer.push_str(&delta.clone());
+                self.conversation_history
+                    .replace_prev_agent_reasoning(&self.config, self.reasoning_buffer.clone());
                 self.request_redraw();
             }
             EventMsg::AgentReasoning(AgentReasoningEvent { text }) => {
-                if !self.config.hide_agent_reasoning {
+                // if the reasoning buffer is empty, this means we haven't received any
+                // delta. Thus, we need to print the message as a new reasoning.
+                if self.reasoning_buffer.is_empty() {
                     self.conversation_history
-                        .add_agent_reasoning(&self.config, text);
-                    self.request_redraw();
+                        .add_agent_reasoning(&self.config, "".to_string());
+                } else {
+                    // else, we rerender one last time.
+                    self.conversation_history
+                        .replace_prev_agent_reasoning(&self.config, text);
                 }
+                self.reasoning_buffer.clear();
+                self.request_redraw();
             }
             EventMsg::TaskStarted => {
                 self.bottom_pane.clear_ctrl_c_quit_hint();
@@ -390,7 +431,7 @@ impl ChatWidget<'_> {
     }
 
     fn request_redraw(&mut self) {
-        self.app_event_tx.send(AppEvent::Redraw);
+        self.app_event_tx.send(AppEvent::RequestRedraw);
     }
 
     pub(crate) fn add_diff_output(&mut self, diff_output: String) {
@@ -432,6 +473,10 @@ impl ChatWidget<'_> {
         }
     }
 
+    pub(crate) fn composer_is_empty(&self) -> bool {
+        self.bottom_pane.composer_is_empty()
+    }
+
     /// Forward an `Op` directly to codex.
     pub(crate) fn submit_op(&self, op: Op) {
         if let Err(e) = self.codex_op_tx.send(op) {

codex-rs/tui/src/conversation_history_widget.rs

@@ -202,6 +202,14 @@ impl ConversationHistoryWidget {
         self.add_to_history(HistoryCell::new_agent_reasoning(config, text));
     }
 
+    pub fn replace_prev_agent_reasoning(&mut self, config: &Config, text: String) {
+        self.replace_last_agent_reasoning(config, text);
+    }
+
+    pub fn replace_prev_agent_message(&mut self, config: &Config, text: String) {
+        self.replace_last_agent_message(config, text);
+    }
+
     pub fn add_background_event(&mut self, message: String) {
         self.add_to_history(HistoryCell::new_background_event(message));
     }
@@ -249,6 +257,42 @@ impl ConversationHistoryWidget {
         });
     }
 
+    pub fn replace_last_agent_reasoning(&mut self, config: &Config, text: String) {
+        if let Some(idx) = self
+            .entries
+            .iter()
+            .rposition(|entry| matches!(entry.cell, HistoryCell::AgentReasoning { .. }))
+        {
+            let width = self.cached_width.get();
+            let entry = &mut self.entries[idx];
+            entry.cell = HistoryCell::new_agent_reasoning(config, text);
+            let height = if width > 0 {
+                entry.cell.height(width)
+            } else {
+                0
+            };
+            entry.line_count.set(height);
+        }
+    }
+
+    pub fn replace_last_agent_message(&mut self, config: &Config, text: String) {
+        if let Some(idx) = self
+            .entries
+            .iter()
+            .rposition(|entry| matches!(entry.cell, HistoryCell::AgentMessage { .. }))
+        {
+            let width = self.cached_width.get();
+            let entry = &mut self.entries[idx];
+            entry.cell = HistoryCell::new_agent_message(config, text);
+            let height = if width > 0 {
+                entry.cell.height(width)
+            } else {
+                0
+            };
+            entry.line_count.set(height);
+        }
+    }
+
     pub fn record_completed_exec_command(
         &mut self,
         call_id: String,
@@ -454,7 +498,7 @@ impl WidgetRef for ConversationHistoryWidget {
 
         {
             // Choose a thumb color that stands out only when this pane has focus so that the
-            // user’s attention is naturally drawn to the active viewport. When unfocused we show
+            // user's attention is naturally drawn to the active viewport. When unfocused we show
             // a low-contrast thumb so the scrollbar fades into the background without becoming
             // invisible.
             let thumb_style = if self.has_input_focus {

codex-rs/tui/src/status_indicator_widget.rs

@@ -65,7 +65,7 @@ impl StatusIndicatorWidget {
                     std::thread::sleep(Duration::from_millis(200));
                     counter = counter.wrapping_add(1);
                     frame_idx_clone.store(counter, Ordering::Relaxed);
-                    app_event_tx_clone.send(AppEvent::Redraw);
+                    app_event_tx_clone.send(AppEvent::RequestRedraw);
                 }
             });
         }