Merge remote-tracking branch 'origin/main' into streaming

Stream model responses (#1810 )
Stream models thoughts and responses instead of waiting for the whole thing to come through. Very rough right now, but I'm making the risk call to push through.
2026-02-06 00:43:40 +00:00 · 2025-08-04 21:24:09 -07:00 · 2025-08-05 04:23:22 +00:00 · 2025-08-04 21:13:23 -07:00 · 2025-08-04 20:56:14 -07:00 · 2025-08-04 19:41:08 -07:00
42 changed files with 2945 additions and 390 deletions
--- a/.github/actions/codex/bun.lock
+++ b/.github/actions/codex/bun.lock
@@ -11,7 +11,7 @@
        "@types/bun": "^1.2.19",
        "@types/node": "^24.1.0",
        "prettier": "^3.6.2",
-        "typescript": "^5.8.3",
+        "typescript": "^5.9.2",
      },
    },
  },
@@ -68,7 +68,7 @@

    "tunnel": ["tunnel@0.0.6", "", {}, "sha512-1h/Lnq9yajKY2PEbBadPXj3VxsDDu844OnaAo52UVmIzIvwwtBPIuNvkjuzBlTWpfJyUbG3ez0KSBibQkj4ojg=="],

-    "typescript": ["typescript@5.8.3", "", { "bin": { "tsc": "bin/tsc", "tsserver": "bin/tsserver" } }, "sha512-p1diW6TqL9L07nNxvRMM7hMMw4c5XOo/1ibL4aAIGmSAt9slTE1Xgw5KWuof2uTOvCg9BY7ZRi+GaF+7sfgPeQ=="],
+    "typescript": ["typescript@5.9.2", "", { "bin": { "tsc": "bin/tsc", "tsserver": "bin/tsserver" } }, "sha512-CWBzXQrc/qOkhidw1OzBTQuYRbfyxDXJMVJ1XNwUHGROVmuaeiEm3OslpZ1RV96d7SKKjZKrSJu3+t/xlw3R9A=="],

    "undici": ["undici@5.29.0", "", { "dependencies": { "@fastify/busboy": "^2.0.0" } }, "sha512-raqeBD6NQK4SkWhQzeYKd1KmIG6dllBOTt55Rmkt4HtI9mwdWtJljnrXjAFUBLTSN67HWrOIZ3EPF4kjUw80Bg=="],

--- a/.github/actions/codex/package.json
+++ b/.github/actions/codex/package.json
@@ -16,6 +16,6 @@
        "@types/bun": "^1.2.19",
        "@types/node": "^24.1.0",
        "prettier": "^3.6.2",
-        "typescript": "^5.8.3"
+        "typescript": "^5.9.2"
    }
 }
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -661,7 +661,7 @@ dependencies = [
 "clap",
 "codex-core",
 "serde",
- "toml 0.9.2",
+ "toml 0.9.4",
 ]

 [[package]]
@@ -699,6 +699,7 @@ dependencies = [
 "serde_json",
 "sha1",
 "shlex",
+ "similar",
 "strum_macros 0.27.2",
 "tempfile",
 "thiserror 2.0.12",
@@ -706,7 +707,7 @@ dependencies = [
 "tokio",
 "tokio-test",
 "tokio-util",
- "toml 0.9.2",
+ "toml 0.9.4",
 "tracing",
 "tree-sitter",
 "tree-sitter-bash",
@@ -830,7 +831,7 @@ dependencies = [
 "tempfile",
 "tokio",
 "tokio-test",
- "toml 0.9.2",
+ "toml 0.9.4",
 "tracing",
 "tracing-subscriber",
 "uuid",
@@ -880,6 +881,7 @@ dependencies = [
 "unicode-segmentation",
 "unicode-width 0.1.14",
 "uuid",
+ "vt100",
 ]

 [[package]]
@@ -1472,7 +1474,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "778e2ac28f6c47af28e4907f13ffd1e1ddbd400980a9abd7c8df189bf578a5ad"
 dependencies = [
 "libc",
- "windows-sys 0.60.2",
+ "windows-sys 0.52.0",
 ]

 [[package]]
@@ -1552,7 +1554,7 @@ checksum = "0ce92ff622d6dadf7349484f42c93271a0d49b7cc4d466a936405bacbe10aa78"
 dependencies = [
 "cfg-if",
 "rustix 1.0.8",
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]

 [[package]]
@@ -1755,7 +1757,7 @@ version = "0.2.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cba6ae63eb948698e300f645f87c70f76630d505f23b8907cf1e193ee85048c1"
 dependencies = [
- "unicode-width 0.2.0",
+ "unicode-width 0.2.1",
 ]

 [[package]]
@@ -2016,7 +2018,7 @@ dependencies = [
 "libc",
 "percent-encoding",
 "pin-project-lite",
- "socket2 0.6.0",
+ "socket2",
 "system-configuration",
 "tokio",
 "tower-service",
@@ -2335,7 +2337,7 @@ checksum = "e04d7f318608d35d4b61ddd75cbdaee86b023ebe2bd5a66ee0915f0bf93095a9"
 dependencies = [
 "hermit-abi",
 "libc",
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]

 [[package]]
@@ -3391,7 +3393,7 @@ dependencies = [
 [[package]]
 name = "ratatui"
 version = "0.29.0"
-source = "git+https://github.com/nornagon/ratatui?branch=nornagon-v0.29.0-patch#bca287ddc5d38fe088c79e2eda22422b96226f2e"
+source = "git+https://github.com/nornagon/ratatui?branch=nornagon-v0.29.0-patch#9b2ad1298408c45918ee9f8241a6f95498cdbed2"
 dependencies = [
 "bitflags 2.9.1",
 "cassowary",
@@ -3405,7 +3407,7 @@ dependencies = [
 "strum 0.26.3",
 "unicode-segmentation",
 "unicode-truncate",
- "unicode-width 0.2.0",
+ "unicode-width 0.2.1",
 ]

 [[package]]
@@ -3719,7 +3721,7 @@ dependencies = [
 "errno",
 "libc",
 "linux-raw-sys 0.4.15",
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]

 [[package]]
@@ -3732,7 +3734,7 @@ dependencies = [
 "errno",
 "libc",
 "linux-raw-sys 0.9.4",
- "windows-sys 0.60.2",
+ "windows-sys 0.52.0",
 ]

 [[package]]
@@ -3996,9 +3998,9 @@ dependencies = [

 [[package]]
 name = "serde_json"
-version = "1.0.141"
+version = "1.0.142"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "30b9eff21ebe718216c6ec64e1d9ac57087aad11efc64e32002bce4a0d4c03d3"
+checksum = "030fedb782600dcbd6f02d479bf0d817ac3bb40d644745b769d6a96bc3afc5a7"
 dependencies = [
 "indexmap 2.10.0",
 "itoa",
@@ -4187,16 +4189,6 @@ version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b7c388c1b5e93756d0c740965c41e8822f866621d41acbdf6336a6a168f8840c"

-[[package]]
-name = "socket2"
-version = "0.5.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e22376abed350d73dd1cd119b57ffccad95b4e585a7cda43e286245ce23c0678"
-dependencies = [
- "libc",
- "windows-sys 0.52.0",
-]
-
 [[package]]
 name = "socket2"
 version = "0.6.0"
@@ -4508,7 +4500,7 @@ dependencies = [
 "getrandom 0.3.3",
 "once_cell",
 "rustix 1.0.8",
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]

 [[package]]
@@ -4555,7 +4547,7 @@ checksum = "c13547615a44dc9c452a8a534638acdf07120d4b6847c8178705da06306a3057"
 dependencies = [
 "smawk",
 "unicode-linebreak",
- "unicode-width 0.2.0",
+ "unicode-width 0.2.1",
 ]

 [[package]]
@@ -4672,9 +4664,9 @@ dependencies = [

 [[package]]
 name = "tokio"
-version = "1.46.1"
+version = "1.47.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0cc3a2344dafbe23a245241fe8b09735b521110d30fcefbbd5feb1797ca35d17"
+checksum = "89e49afdadebb872d3145a5638b59eb0691ea23e46ca484037cfab3b76b95038"
 dependencies = [
 "backtrace",
 "bytes",
@@ -4685,9 +4677,9 @@ dependencies = [
 "pin-project-lite",
 "signal-hook-registry",
 "slab",
- "socket2 0.5.10",
+ "socket2",
 "tokio-macros",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]

 [[package]]
@@ -4772,9 +4764,9 @@ dependencies = [

 [[package]]
 name = "toml"
-version = "0.9.2"
+version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed0aee96c12fa71097902e0bb061a5e1ebd766a6636bb605ba401c45c1650eac"
+checksum = "41ae868b5a0f67631c14589f7e250c1ea2c574ee5ba21c6c8dd4b1485705a5a1"
 dependencies = [
 "indexmap 2.10.0",
 "serde",
@@ -5003,7 +4995,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "911e93158bf80bbc94bad533b2b16e3d711e1132d69a6a6980c3920a63422c19"
 dependencies = [
 "ratatui",
- "unicode-width 0.2.0",
+ "unicode-width 0.2.1",
 ]

 [[package]]
@@ -5071,9 +5063,9 @@ checksum = "7dd6e30e90baa6f72411720665d41d89b9a3d039dc45b8faea1ddd07f617f6af"

 [[package]]
 name = "unicode-width"
-version = "0.2.0"
+version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1fc81956842c57dac11422a97c3b8195a1ff727f06e85c84ed2e8aa277c9a0fd"
+checksum = "4a1a07cc7db3810833284e8d372ccdc6da29741639ecc70c9ec107df0fa6154c"

 [[package]]
 name = "unicode-xid"
@@ -5158,6 +5150,27 @@ version = "0.9.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"

+[[package]]
+name = "vt100"
+version = "0.16.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "054ff75fb8fa83e609e685106df4faeffdf3a735d3c74ebce97ec557d5d36fd9"
+dependencies = [
+ "itoa",
+ "unicode-width 0.2.1",
+ "vte",
+]
+
+[[package]]
+name = "vte"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a5924018406ce0063cd67f8e008104968b74b563ee1b85dde3ed1f7cb87d3dbd"
+dependencies = [
+ "arrayvec",
+ "memchr",
+]
+
 [[package]]
 name = "wait-timeout"
 version = "0.2.1"
@@ -5346,7 +5359,7 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
 dependencies = [
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]

 [[package]]
--- a/codex-rs/core/Cargo.toml
+++ b/codex-rs/core/Cargo.toml
@@ -34,6 +34,7 @@ serde_json = "1"
 serde_bytes = "0.11"
 sha1 = "0.10.6"
 shlex = "1.3.0"
+similar = "2.7.0"
 strum_macros = "0.27.2"
 thiserror = "2.0.12"
 time = { version = "0.3", features = ["formatting", "local-offset", "macros"] }
@@ -45,7 +46,7 @@ tokio = { version = "1", features = [
    "signal",
 ] }
 tokio-util = "0.7.14"
-toml = "0.9.2"
+toml = "0.9.4"
 tracing = { version = "0.1.41", features = ["log"] }
 tree-sitter = "0.25.8"
 tree-sitter-bash = "0.25.0"
--- a/codex-rs/core/prompt.md
+++ b/codex-rs/core/prompt.md
@@ -9,8 +9,10 @@ You MUST adhere to the following criteria when executing the task:
 - Analyzing code for vulnerabilities is allowed.
 - Showing user code and tool call details is allowed.
 - User instructions may overwrite the _CODING GUIDELINES_ section in this developer message.
+- `user_instructions` are not part of the user's request, but guidance for how to complete the task.
+- Do not cite `user_instructions` back to the user unless a specific piece is relevant.
 - Do not use \`ls -R\`, \`find\`, or \`grep\` - these are slow in large repos. Use \`rg\` and \`rg --files\`.
- Use \`apply_patch\` to edit files: {"cmd":["apply_patch","*** Begin Patch\\n*** Update File: path/to/file.py\\n@@ def example():\\n- pass\\n+ return 123\\n*** End Patch"]}
+- Use \`apply_patch\` to edit files: {"command":["apply_patch","*** Begin Patch\\n*** Update File: path/to/file.py\\n@@ def example():\\n- pass\\n+ return 123\\n*** End Patch"]}
 - If completing the user's task requires writing or modifying files:
  - Your code and final answer should follow these _CODING GUIDELINES_:
    - Fix the problem at the root cause rather than applying surface-level patches, when possible.
@@ -40,16 +42,16 @@ You MUST adhere to the following criteria when executing the task:

 Your patch language is a stripped‑down, file‑oriented diff format designed to be easy to parse and safe to apply. You can think of it as a high‑level envelope:

-**_ Begin Patch
+*** Begin Patch
 [ one or more file sections ]
-_** End Patch
+*** End Patch

 Within that envelope, you get a sequence of file operations.
 You MUST include a header to specify the action you are taking.
 Each operation starts with one of three headers:

-**_ Add File: <path> - create a new file. Every following line is a + line (the initial contents).
-_** Delete File: <path> - remove an existing file. Nothing follows.
+*** Add File: <path> - create a new file. Every following line is a + line (the initial contents).
+*** Delete File: <path> - remove an existing file. Nothing follows.
 \*\*\* Update File: <path> - patch an existing file in place (optionally with a rename).

 May be immediately followed by \*\*\* Move to: <new path> if you want to rename the file.
@@ -63,28 +65,28 @@ Within a hunk each line starts with:
  At the end of a truncated hunk you can emit \*\*\* End of File.

 Patch := Begin { FileOp } End
-Begin := "**_ Begin Patch" NEWLINE
-End := "_** End Patch" NEWLINE
+Begin := "*** Begin Patch" NEWLINE
+End := "*** End Patch" NEWLINE
 FileOp := AddFile | DeleteFile | UpdateFile
-AddFile := "**_ Add File: " path NEWLINE { "+" line NEWLINE }
-DeleteFile := "_** Delete File: " path NEWLINE
-UpdateFile := "**_ Update File: " path NEWLINE [ MoveTo ] { Hunk }
-MoveTo := "_** Move to: " newPath NEWLINE
+AddFile := "*** Add File: " path NEWLINE { "+" line NEWLINE }
+DeleteFile := "*** Delete File: " path NEWLINE
+UpdateFile := "*** Update File: " path NEWLINE [ MoveTo ] { Hunk }
+MoveTo := "*** Move to: " newPath NEWLINE
 Hunk := "@@" [ header ] NEWLINE { HunkLine } [ "*** End of File" NEWLINE ]
 HunkLine := (" " | "-" | "+") text NEWLINE

 A full patch can combine several operations:

-**_ Begin Patch
-_** Add File: hello.txt
+*** Begin Patch
+*** Add File: hello.txt
 +Hello world
-**_ Update File: src/app.py
-_** Move to: src/main.py
+*** Update File: src/app.py
+*** Move to: src/main.py
@@ def greet():
 -print("Hi")
 +print("Hello, world!")
-**_ Delete File: obsolete.txt
-_** End Patch
+*** Delete File: obsolete.txt
+*** End Patch

 It is important to remember:

@@ -101,7 +103,7 @@ Plan updates

 A tool named `update_plan` is available. Use it to keep an up‑to‑date, step‑by‑step plan for the task so you can follow your progress. When making your plans, keep in mind that you are a deployed coding agent - `update_plan` calls should not involve doing anything that you aren't capable of doing. For example, `update_plan` calls should NEVER contain tasks to merge your own pull requests. Only stop to ask the user if you genuinely need their feedback on a change.

- At the start of the task, call `update_plan` with an initial plan: a short list of 1‑sentence steps with a `status` for each step (`pending`, `in_progress`, or `completed`). There should always be exactly one `in_progress` step until everything is done.
+- At the start of any nontrivial task, call `update_plan` with an initial plan: a short list of 1‑sentence steps with a `status` for each step (`pending`, `in_progress`, or `completed`). There should always be exactly one `in_progress` step until everything is done.
 - Whenever you finish a step, call `update_plan` again, marking the finished step as `completed` and the next step as `in_progress`.
 - If your plan needs to change, call `update_plan` with the revised steps and include an `explanation` describing the change.
 - When all steps are complete, make a final `update_plan` call with all steps marked `completed`.
--- a/codex-rs/core/src/chat_completions.rs
+++ b/codex-rs/core/src/chat_completions.rs
@@ -40,7 +40,7 @@ pub(crate) async fn stream_chat_completions(
    let full_instructions = prompt.get_full_instructions(model);
    messages.push(json!({"role": "system", "content": full_instructions}));

-    if let Some(instr) = &prompt.user_instructions {
+    if let Some(instr) = &prompt.get_formatted_user_instructions() {
        messages.push(json!({"role": "user", "content": instr}));
    }

@@ -120,7 +120,7 @@ pub(crate) async fn stream_chat_completions(

    debug!(
        "POST to {}: {}",
-        provider.get_full_url(),
+        provider.get_full_url(&None),
        serde_json::to_string_pretty(&payload).unwrap_or_default()
    );

@@ -129,7 +129,7 @@ pub(crate) async fn stream_chat_completions(
    loop {
        attempt += 1;

-        let req_builder = provider.create_request_builder(client)?;
+        let req_builder = provider.create_request_builder(client, &None).await?;

        let res = req_builder
            .header(reqwest::header::ACCEPT, "text/event-stream")
@@ -260,6 +260,11 @@ async fn process_chat_sse<S>(
                .and_then(|d| d.get("content"))
                .and_then(|c| c.as_str())
            {
+                // Emit a delta so downstream consumers can stream text live.
+                let _ = tx_event
+                    .send(Ok(ResponseEvent::OutputTextDelta(content.to_string())))
+                    .await;
+
                let item = ResponseItem::Message {
                    role: "assistant".to_string(),
                    content: vec![ContentItem::OutputText {
@@ -439,11 +444,14 @@ 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;
+                Poll::Ready(Some(Ok(ResponseEvent::OutputTextDelta(delta)))) => {
+                    // Forward deltas unchanged so callers can stream text
+                    // live while still receiving a single aggregated
+                    // OutputItemDone at the end of the turn.
+                    return Poll::Ready(Some(Ok(ResponseEvent::OutputTextDelta(delta))));
+                }
+                Poll::Ready(Some(Ok(ResponseEvent::ReasoningSummaryDelta(delta)))) => {
+                    return Poll::Ready(Some(Ok(ResponseEvent::ReasoningSummaryDelta(delta))));
                }
            }
        }
--- a/codex-rs/core/src/client.rs
+++ b/codex-rs/core/src/client.rs
@@ -30,7 +30,6 @@ use crate::config::Config;
 use crate::config_types::ReasoningEffort as ReasoningEffortConfig;
 use crate::config_types::ReasoningSummary as ReasoningSummaryConfig;
 use crate::error::CodexErr;
-use crate::error::EnvVarError;
 use crate::error::Result;
 use crate::flags::CODEX_RS_SSE_FIXTURE;
 use crate::model_provider_info::ModelProviderInfo;
@@ -122,24 +121,11 @@ impl ModelClient {
            return stream_from_fixture(path, self.provider.clone()).await;
        }

-        let auth = self.auth.as_ref().ok_or_else(|| {
-            CodexErr::EnvVar(EnvVarError {
-                var: "OPENAI_API_KEY".to_string(),
-                instructions: Some("Create an API key (https://platform.openai.com) and export it as an environment variable.".to_string()),
-            })
-        })?;
+        let auth = self.auth.clone();

-        let store = prompt.store && auth.mode != AuthMode::ChatGPT;
+        let auth_mode = auth.as_ref().map(|a| a.mode);

-        let base_url = match self.provider.base_url.clone() {
-            Some(url) => url,
-            None => match auth.mode {
-                AuthMode::ChatGPT => "https://chatgpt.com/backend-api/codex".to_string(),
-                AuthMode::ApiKey => "https://api.openai.com/v1".to_string(),
-            },
-        };
-
-        let token = auth.get_token().await?;
+        let store = prompt.store && auth_mode != Some(AuthMode::ChatGPT);

        let full_instructions = prompt.get_full_instructions(&self.config.model);
        let tools_json = create_tools_json_for_responses_api(
@@ -158,11 +144,11 @@ impl ModelClient {
        };

        let mut input_with_instructions = Vec::with_capacity(prompt.input.len() + 1);
-        if let Some(ui) = &prompt.user_instructions {
+        if let Some(ui) = prompt.get_formatted_user_instructions() {
            input_with_instructions.push(ResponseItem::Message {
                id: None,
                role: "user".to_string(),
-                content: vec![ContentItem::InputText { text: ui.clone() }],
+                content: vec![ContentItem::InputText { text: ui }],
            });
        }
        input_with_instructions.extend(prompt.input.clone());
@@ -180,35 +166,36 @@ impl ModelClient {
            include,
        };

-        trace!(
-            "POST to {}: {}",
-            self.provider.get_full_url(),
-            serde_json::to_string(&payload)?
-        );
-
        let mut attempt = 0;
        let max_retries = self.provider.request_max_retries();

+        trace!(
+            "POST to {}: {}",
+            self.provider.get_full_url(&auth),
+            serde_json::to_string(&payload)?
+        );
+
        loop {
            attempt += 1;

            let mut req_builder = self
-                .client
-                .post(format!("{base_url}/responses"))
+                .provider
+                .create_request_builder(&self.client, &auth)
+                .await?;
+
+            req_builder = req_builder
                .header("OpenAI-Beta", "responses=experimental")
                .header("session_id", self.session_id.to_string())
-                .bearer_auth(&token)
                .header(reqwest::header::ACCEPT, "text/event-stream")
                .json(&payload);

-            if auth.mode == AuthMode::ChatGPT {
-                if let Some(account_id) = auth.get_account_id().await {
-                    req_builder = req_builder.header("chatgpt-account-id", account_id);
-                }
+            if let Some(auth) = auth.as_ref()
+                && auth.mode == AuthMode::ChatGPT
+                && let Some(account_id) = auth.get_account_id().await
+            {
+                req_builder = req_builder.header("chatgpt-account-id", account_id);
            }

-            req_builder = self.provider.apply_http_headers(req_builder);
-
            let originator = self
                .config
                .internal_originator
--- a/codex-rs/core/src/client_common.rs
+++ b/codex-rs/core/src/client_common.rs
@@ -17,6 +17,10 @@ use tokio::sync::mpsc;
 /// with this content.
 const BASE_INSTRUCTIONS: &str = include_str!("../prompt.md");

+/// wraps user instructions message in a tag for the model to parse more easily.
+const USER_INSTRUCTIONS_START: &str = "<user_instructions>\n\n";
+const USER_INSTRUCTIONS_END: &str = "\n\n</user_instructions>";
+
 /// API request payload for a single model turn.
 #[derive(Default, Debug, Clone)]
 pub struct Prompt {
@@ -49,6 +53,12 @@ impl Prompt {
        }
        Cow::Owned(sections.join("\n"))
    }
+
+    pub(crate) fn get_formatted_user_instructions(&self) -> Option<String> {
+        self.user_instructions
+            .as_ref()
+            .map(|ui| format!("{USER_INSTRUCTIONS_START}{ui}{USER_INSTRUCTIONS_END}"))
+    }
 }

 #[derive(Debug)]
--- a/codex-rs/core/src/codex.rs
+++ b/codex-rs/core/src/codex.rs
@@ -85,11 +85,13 @@ use crate::protocol::SandboxPolicy;
 use crate::protocol::SessionConfiguredEvent;
 use crate::protocol::Submission;
 use crate::protocol::TaskCompleteEvent;
+use crate::protocol::TurnDiffEvent;
 use crate::rollout::RolloutRecorder;
 use crate::safety::SafetyCheck;
 use crate::safety::assess_command_safety;
 use crate::safety::assess_safety_for_untrusted_command;
 use crate::shell;
+use crate::turn_diff_tracker::TurnDiffTracker;
 use crate::user_notification::UserNotification;
 use crate::util::backoff;

@@ -121,7 +123,7 @@ impl Codex {
        let resume_path = config.experimental_resume.clone();
        info!("resume_path: {resume_path:?}");
        let (tx_sub, rx_sub) = async_channel::bounded(64);
-        let (tx_event, rx_event) = async_channel::bounded(1600);
+        let (tx_event, rx_event) = async_channel::unbounded();

        let user_instructions = get_user_instructions(&config).await;

@@ -362,7 +364,11 @@ impl Session {
        }
    }

-    async fn notify_exec_command_begin(&self, exec_command_context: ExecCommandContext) {
+    async fn on_exec_command_begin(
+        &self,
+        turn_diff_tracker: &mut TurnDiffTracker,
+        exec_command_context: ExecCommandContext,
+    ) {
        let ExecCommandContext {
            sub_id,
            call_id,
@@ -374,11 +380,15 @@ impl Session {
            Some(ApplyPatchCommandContext {
                user_explicitly_approved_this_action,
                changes,
-            }) => EventMsg::PatchApplyBegin(PatchApplyBeginEvent {
-                call_id,
-                auto_approved: !user_explicitly_approved_this_action,
-                changes,
-            }),
+            }) => {
+                turn_diff_tracker.on_patch_begin(&changes);
+
+                EventMsg::PatchApplyBegin(PatchApplyBeginEvent {
+                    call_id,
+                    auto_approved: !user_explicitly_approved_this_action,
+                    changes,
+                })
+            }
            None => EventMsg::ExecCommandBegin(ExecCommandBeginEvent {
                call_id,
                command: command_for_display.clone(),
@@ -392,8 +402,10 @@ impl Session {
        let _ = self.tx_event.send(event).await;
    }

-    async fn notify_exec_command_end(
+    #[allow(clippy::too_many_arguments)]
+    async fn on_exec_command_end(
        &self,
+        turn_diff_tracker: &mut TurnDiffTracker,
        sub_id: &str,
        call_id: &str,
        output: &ExecToolCallOutput,
@@ -433,6 +445,20 @@ impl Session {
            msg,
        };
        let _ = self.tx_event.send(event).await;
+
+        // If this is an apply_patch, after we emit the end patch, emit a second event
+        // with the full turn diff if there is one.
+        if is_apply_patch {
+            let unified_diff = turn_diff_tracker.get_unified_diff();
+            if let Ok(Some(unified_diff)) = unified_diff {
+                let msg = EventMsg::TurnDiff(TurnDiffEvent { unified_diff });
+                let event = Event {
+                    id: sub_id.into(),
+                    msg,
+                };
+                let _ = self.tx_event.send(event).await;
+            }
+        }
    }

    /// Helper that emits a BackgroundEvent with the given message. This keeps
@@ -675,7 +701,7 @@ async fn submission_loop(
                cwd,
                resume_path,
            } => {
-                info!(
+                debug!(
                    "Configuring session: model={model}; provider={provider:?}; resume={resume_path:?}"
                );
                if !cwd.is_absolute() {
@@ -1006,6 +1032,10 @@ async fn run_task(sess: Arc<Session>, sub_id: String, input: Vec<InputItem>) {
        .await;

    let last_agent_message: Option<String>;
+    // Although from the perspective of codex.rs, TurnDiffTracker has the lifecycle of a Task which contains
+    // many turns, from the perspective of the user, it is a single turn.
+    let mut turn_diff_tracker = TurnDiffTracker::new();
+
    loop {
        // Note that pending_input would be something like a message the user
        // submitted through the UI while the model was running. Though the UI
@@ -1037,7 +1067,7 @@ async fn run_task(sess: Arc<Session>, sub_id: String, input: Vec<InputItem>) {
                })
            })
            .collect();
-        match run_turn(&sess, sub_id.clone(), turn_input).await {
+        match run_turn(&sess, &mut turn_diff_tracker, sub_id.clone(), turn_input).await {
            Ok(turn_output) => {
                let mut items_to_record_in_conversation_history = Vec::<ResponseItem>::new();
                let mut responses = Vec::<ResponseInputItem>::new();
@@ -1163,6 +1193,7 @@ async fn run_task(sess: Arc<Session>, sub_id: String, input: Vec<InputItem>) {

 async fn run_turn(
    sess: &Session,
+    turn_diff_tracker: &mut TurnDiffTracker,
    sub_id: String,
    input: Vec<ResponseItem>,
 ) -> CodexResult<Vec<ProcessedResponseItem>> {
@@ -1177,7 +1208,7 @@ async fn run_turn(

    let mut retries = 0;
    loop {
-        match try_run_turn(sess, &sub_id, &prompt).await {
+        match try_run_turn(sess, turn_diff_tracker, &sub_id, &prompt).await {
            Ok(output) => return Ok(output),
            Err(CodexErr::Interrupted) => return Err(CodexErr::Interrupted),
            Err(CodexErr::EnvVar(var)) => return Err(CodexErr::EnvVar(var)),
@@ -1223,6 +1254,7 @@ struct ProcessedResponseItem {

 async fn try_run_turn(
    sess: &Session,
+    turn_diff_tracker: &mut TurnDiffTracker,
    sub_id: &str,
    prompt: &Prompt,
 ) -> CodexResult<Vec<ProcessedResponseItem>> {
@@ -1310,7 +1342,8 @@ async fn try_run_turn(
        match event {
            ResponseEvent::Created => {}
            ResponseEvent::OutputItemDone(item) => {
-                let response = handle_response_item(sess, sub_id, item.clone()).await?;
+                let response =
+                    handle_response_item(sess, turn_diff_tracker, sub_id, item.clone()).await?;

                output.push(ProcessedResponseItem { item, response });
            }
@@ -1328,9 +1361,24 @@ async fn try_run_turn(
                        .ok();
                }

+                let unified_diff = turn_diff_tracker.get_unified_diff();
+                if let Ok(Some(unified_diff)) = unified_diff {
+                    let msg = EventMsg::TurnDiff(TurnDiffEvent { unified_diff });
+                    let event = Event {
+                        id: sub_id.to_string(),
+                        msg,
+                    };
+                    let _ = sess.tx_event.send(event).await;
+                }
+
                return Ok(output);
            }
            ResponseEvent::OutputTextDelta(delta) => {
+                {
+                    let mut st = sess.state.lock().unwrap();
+                    st.history.append_assistant_text(&delta);
+                }
+
                let event = Event {
                    id: sub_id.to_string(),
                    msg: EventMsg::AgentMessageDelta(AgentMessageDeltaEvent { delta }),
@@ -1432,6 +1480,7 @@ async fn run_compact_task(

 async fn handle_response_item(
    sess: &Session,
+    turn_diff_tracker: &mut TurnDiffTracker,
    sub_id: &str,
    item: ResponseItem,
 ) -> CodexResult<Option<ResponseInputItem>> {
@@ -1469,7 +1518,17 @@ async fn handle_response_item(
            ..
        } => {
            info!("FunctionCall: {arguments}");
-            Some(handle_function_call(sess, sub_id.to_string(), name, arguments, call_id).await)
+            Some(
+                handle_function_call(
+                    sess,
+                    turn_diff_tracker,
+                    sub_id.to_string(),
+                    name,
+                    arguments,
+                    call_id,
+                )
+                .await,
+            )
        }
        ResponseItem::LocalShellCall {
            id,
@@ -1504,6 +1563,7 @@ async fn handle_response_item(
                handle_container_exec_with_params(
                    exec_params,
                    sess,
+                    turn_diff_tracker,
                    sub_id.to_string(),
                    effective_call_id,
                )
@@ -1521,6 +1581,7 @@ async fn handle_response_item(

 async fn handle_function_call(
    sess: &Session,
+    turn_diff_tracker: &mut TurnDiffTracker,
    sub_id: String,
    name: String,
    arguments: String,
@@ -1534,7 +1595,8 @@ async fn handle_function_call(
                    return *output;
                }
            };
-            handle_container_exec_with_params(params, sess, sub_id, call_id).await
+            handle_container_exec_with_params(params, sess, turn_diff_tracker, sub_id, call_id)
+                .await
        }
        "update_plan" => handle_update_plan(sess, arguments, sub_id, call_id).await,
        _ => {
@@ -1608,6 +1670,7 @@ fn maybe_run_with_user_profile(params: ExecParams, sess: &Session) -> ExecParams
 async fn handle_container_exec_with_params(
    params: ExecParams,
    sess: &Session,
+    turn_diff_tracker: &mut TurnDiffTracker,
    sub_id: String,
    call_id: String,
 ) -> ResponseInputItem {
@@ -1755,7 +1818,7 @@ async fn handle_container_exec_with_params(
            },
        ),
    };
-    sess.notify_exec_command_begin(exec_command_context.clone())
+    sess.on_exec_command_begin(turn_diff_tracker, exec_command_context.clone())
        .await;

    let params = maybe_run_with_user_profile(params, sess);
@@ -1782,7 +1845,8 @@ async fn handle_container_exec_with_params(
                duration,
            } = &output;

-            sess.notify_exec_command_end(
+            sess.on_exec_command_end(
+                turn_diff_tracker,
                &sub_id,
                &call_id,
                &output,
@@ -1806,7 +1870,15 @@ async fn handle_container_exec_with_params(
            }
        }
        Err(CodexErr::Sandbox(error)) => {
-            handle_sandbox_error(params, exec_command_context, error, sandbox_type, sess).await
+            handle_sandbox_error(
+                turn_diff_tracker,
+                params,
+                exec_command_context,
+                error,
+                sandbox_type,
+                sess,
+            )
+            .await
        }
        Err(e) => {
            // Handle non-sandbox errors
@@ -1822,6 +1894,7 @@ async fn handle_container_exec_with_params(
 }

 async fn handle_sandbox_error(
+    turn_diff_tracker: &mut TurnDiffTracker,
    params: ExecParams,
    exec_command_context: ExecCommandContext,
    error: SandboxErr,
@@ -1853,7 +1926,8 @@ async fn handle_sandbox_error(
    // include additional metadata on the command to indicate whether non-zero
    // exit codes merit a retry.

-    // For now, we categorically ask the user to retry without sandbox.
+    // For now, we categorically ask the user to retry without sandbox and
+    // emit the raw error as a background event.
    sess.notify_background_event(&sub_id, format!("Execution failed: {error}"))
        .await;

@@ -1878,7 +1952,8 @@ async fn handle_sandbox_error(
            sess.notify_background_event(&sub_id, "retrying command without sandbox")
                .await;

-            sess.notify_exec_command_begin(exec_command_context).await;
+            sess.on_exec_command_begin(turn_diff_tracker, exec_command_context)
+                .await;

            // This is an escalated retry; the policy will not be
            // examined and the sandbox has been set to `None`.
@@ -1905,8 +1980,14 @@ async fn handle_sandbox_error(
                        duration,
                    } = &retry_output;

-                    sess.notify_exec_command_end(&sub_id, &call_id, &retry_output, is_apply_patch)
-                        .await;
+                    sess.on_exec_command_end(
+                        turn_diff_tracker,
+                        &sub_id,
+                        &call_id,
+                        &retry_output,
+                        is_apply_patch,
+                    )
+                    .await;

                    let is_success = *exit_code == 0;
                    let content = format_exec_output(
--- a/codex-rs/core/src/config.rs
+++ b/codex-rs/core/src/config.rs
@@ -480,10 +480,12 @@ impl Config {
        // Load base instructions override from a file if specified. If the
        // path is relative, resolve it against the effective cwd so the
        // behaviour matches other path-like config values.
-        let file_base_instructions = Self::get_base_instructions(
-            cfg.experimental_instructions_file.as_ref(),
-            &resolved_cwd,
-        )?;
+        let experimental_instructions_path = config_profile
+            .experimental_instructions_file
+            .as_ref()
+            .or(cfg.experimental_instructions_file.as_ref());
+        let file_base_instructions =
+            Self::get_base_instructions(experimental_instructions_path, &resolved_cwd)?;
        let base_instructions = base_instructions.or(file_base_instructions);

        let config = Self {
--- a/codex-rs/core/src/config_profile.rs
+++ b/codex-rs/core/src/config_profile.rs
@@ -1,4 +1,5 @@
 use serde::Deserialize;
+use std::path::PathBuf;

 use crate::config_types::ReasoningEffort;
 use crate::config_types::ReasoningSummary;
@@ -17,4 +18,5 @@ pub struct ConfigProfile {
    pub model_reasoning_effort: Option<ReasoningEffort>,
    pub model_reasoning_summary: Option<ReasoningSummary>,
    pub chatgpt_base_url: Option<String>,
+    pub experimental_instructions_file: Option<PathBuf>,
 }
--- a/codex-rs/core/src/conversation_history.rs
+++ b/codex-rs/core/src/conversation_history.rs
@@ -24,9 +24,52 @@ impl ConversationHistory {
        I::Item: std::ops::Deref<Target = ResponseItem>,
    {
        for item in items {
-            if is_api_message(&item) {
-                // Note agent-loop.ts also does filtering on some of the fields.
-                self.items.push(item.clone());
+            if !is_api_message(&item) {
+                continue;
+            }
+
+            // Merge adjacent assistant messages into a single history entry.
+            // This prevents duplicates when a partial assistant message was
+            // streamed into history earlier in the turn and the final full
+            // message is recorded at turn end.
+            match (&*item, self.items.last_mut()) {
+                (
+                    ResponseItem::Message {
+                        role: new_role,
+                        content: new_content,
+                        ..
+                    },
+                    Some(ResponseItem::Message {
+                        role: last_role,
+                        content: last_content,
+                        ..
+                    }),
+                ) if new_role == "assistant" && last_role == "assistant" => {
+                    append_text_content(last_content, new_content);
+                }
+                _ => {
+                    self.items.push(item.clone());
+                }
+            }
+        }
+    }
+
+    /// Append a text `delta` to the latest assistant message, creating a new
+    /// assistant entry if none exists yet (e.g. first delta for this turn).
+    pub(crate) fn append_assistant_text(&mut self, delta: &str) {
+        match self.items.last_mut() {
+            Some(ResponseItem::Message { role, content, .. }) if role == "assistant" => {
+                append_text_delta(content, delta);
+            }
+            _ => {
+                // Start a new assistant message with the delta.
+                self.items.push(ResponseItem::Message {
+                    id: None,
+                    role: "assistant".to_string(),
+                    content: vec![crate::models::ContentItem::OutputText {
+                        text: delta.to_string(),
+                    }],
+                });
            }
        }
    }
@@ -72,3 +115,140 @@ fn is_api_message(message: &ResponseItem) -> bool {
        ResponseItem::Other => false,
    }
 }
+
+/// Helper to append the textual content from `src` into `dst` in place.
+fn append_text_content(
+    dst: &mut Vec<crate::models::ContentItem>,
+    src: &Vec<crate::models::ContentItem>,
+) {
+    for c in src {
+        if let crate::models::ContentItem::OutputText { text } = c {
+            append_text_delta(dst, text);
+        }
+    }
+}
+
+/// Append a single text delta to the last OutputText item in `content`, or
+/// push a new OutputText item if none exists.
+fn append_text_delta(content: &mut Vec<crate::models::ContentItem>, delta: &str) {
+    if let Some(crate::models::ContentItem::OutputText { text }) = content
+        .iter_mut()
+        .rev()
+        .find(|c| matches!(c, crate::models::ContentItem::OutputText { .. }))
+    {
+        text.push_str(delta);
+    } else {
+        content.push(crate::models::ContentItem::OutputText {
+            text: delta.to_string(),
+        });
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::models::ContentItem;
+
+    fn assistant_msg(text: &str) -> ResponseItem {
+        ResponseItem::Message {
+            id: None,
+            role: "assistant".to_string(),
+            content: vec![ContentItem::OutputText {
+                text: text.to_string(),
+            }],
+        }
+    }
+
+    fn user_msg(text: &str) -> ResponseItem {
+        ResponseItem::Message {
+            id: None,
+            role: "user".to_string(),
+            content: vec![ContentItem::OutputText {
+                text: text.to_string(),
+            }],
+        }
+    }
+
+    #[test]
+    fn merges_adjacent_assistant_messages() {
+        let mut h = ConversationHistory::default();
+        let a1 = assistant_msg("Hello");
+        let a2 = assistant_msg(", world!");
+        h.record_items([&a1, &a2]);
+
+        let items = h.contents();
+        assert_eq!(
+            items,
+            vec![ResponseItem::Message {
+                id: None,
+                role: "assistant".to_string(),
+                content: vec![ContentItem::OutputText {
+                    text: "Hello, world!".to_string()
+                }]
+            }]
+        );
+    }
+
+    #[test]
+    fn append_assistant_text_creates_and_appends() {
+        let mut h = ConversationHistory::default();
+        h.append_assistant_text("Hello");
+        h.append_assistant_text(", world");
+
+        // Now record a final full assistant message and verify it merges.
+        let final_msg = assistant_msg("!");
+        h.record_items([&final_msg]);
+
+        let items = h.contents();
+        assert_eq!(
+            items,
+            vec![ResponseItem::Message {
+                id: None,
+                role: "assistant".to_string(),
+                content: vec![ContentItem::OutputText {
+                    text: "Hello, world!".to_string()
+                }]
+            }]
+        );
+    }
+
+    #[test]
+    fn filters_non_api_messages() {
+        let mut h = ConversationHistory::default();
+        // System message is not an API message; Other is ignored.
+        let system = ResponseItem::Message {
+            id: None,
+            role: "system".to_string(),
+            content: vec![ContentItem::OutputText {
+                text: "ignored".to_string(),
+            }],
+        };
+        h.record_items([&system, &ResponseItem::Other]);
+
+        // User and assistant should be retained.
+        let u = user_msg("hi");
+        let a = assistant_msg("hello");
+        h.record_items([&u, &a]);
+
+        let items = h.contents();
+        assert_eq!(
+            items,
+            vec![
+                ResponseItem::Message {
+                    id: None,
+                    role: "user".to_string(),
+                    content: vec![ContentItem::OutputText {
+                        text: "hi".to_string()
+                    }]
+                },
+                ResponseItem::Message {
+                    id: None,
+                    role: "assistant".to_string(),
+                    content: vec![ContentItem::OutputText {
+                        text: "hello".to_string()
+                    }]
+                }
+            ]
+        );
+    }
+}
--- a/codex-rs/core/src/exec.rs
+++ b/codex-rs/core/src/exec.rs
@@ -140,11 +140,7 @@ pub async fn process_exec_tool_call(

            let exit_code = raw_output.exit_status.code().unwrap_or(-1);

-            // NOTE(ragona): This is much less restrictive than the previous check. If we exec
-            // a command, and it returns anything other than success, we assume that it may have
-            // been a sandboxing error and allow the user to retry. (The user of course may choose
-            // not to retry, or in a non-interactive mode, would automatically reject the approval.)
-            if exit_code != 0 && sandbox_type != SandboxType::None {
+            if exit_code != 0 && is_likely_sandbox_denied(sandbox_type, exit_code) {
                return Err(CodexErr::Sandbox(SandboxErr::Denied(
                    exit_code, stdout, stderr,
                )));
@@ -223,6 +219,26 @@ fn create_linux_sandbox_command_args(
    linux_cmd
 }

+/// We don't have a fully deterministic way to tell if our command failed
+/// because of the sandbox - a command in the user's zshrc file might hit an
+/// error, but the command itself might fail or succeed for other reasons.
+/// For now, we conservatively check for 'command not found' (exit code 127),
+/// and can add additional cases as necessary.
+fn is_likely_sandbox_denied(sandbox_type: SandboxType, exit_code: i32) -> bool {
+    if sandbox_type == SandboxType::None {
+        return false;
+    }
+
+    // Quick rejects: well-known non-sandbox shell exit codes
+    // 127: command not found, 2: misuse of shell builtins
+    if exit_code == 127 {
+        return false;
+    }
+
+    // For all other cases, we assume the sandbox is the cause
+    true
+}
+
 #[derive(Debug)]
 pub struct RawExecToolCallOutput {
    pub exit_status: ExitStatus,
--- a/codex-rs/core/src/lib.rs
+++ b/codex-rs/core/src/lib.rs
@@ -38,12 +38,14 @@ pub mod plan_tool;
 mod project_doc;
 pub mod protocol;
 mod rollout;
-mod safety;
+pub(crate) mod safety;
 pub mod seatbelt;
 pub mod shell;
 pub mod spawn;
+pub mod turn_diff_tracker;
 mod user_notification;
 pub mod util;

 pub use apply_patch::CODEX_APPLY_PATCH_ARG1;
 pub use client_common::model_supports_reasoning_summaries;
+pub use safety::get_platform_sandbox;
--- a/codex-rs/core/src/model_provider_info.rs
+++ b/codex-rs/core/src/model_provider_info.rs
@@ -5,8 +5,11 @@
 //!   2. User-defined entries inside `~/.codex/config.toml` under the `model_providers`
 //!      key. These override or extend the defaults at runtime.

+use codex_login::AuthMode;
+use codex_login::CodexAuth;
 use serde::Deserialize;
 use serde::Serialize;
+use std::borrow::Cow;
 use std::collections::HashMap;
 use std::env::VarError;
 use std::time::Duration;
@@ -88,25 +91,30 @@ impl ModelProviderInfo {
    /// When `require_api_key` is true and the provider declares an `env_key`
    /// but the variable is missing/empty, returns an [`Err`] identical to the
    /// one produced by [`ModelProviderInfo::api_key`].
-    pub fn create_request_builder<'a>(
+    pub async fn create_request_builder<'a>(
        &'a self,
        client: &'a reqwest::Client,
+        auth: &Option<CodexAuth>,
    ) -> crate::error::Result<reqwest::RequestBuilder> {
-        let url = self.get_full_url();
+        let auth: Cow<'_, Option<CodexAuth>> = if auth.is_some() {
+            Cow::Borrowed(auth)
+        } else {
+            Cow::Owned(self.get_fallback_auth()?)
+        };
+
+        let url = self.get_full_url(&auth);

        let mut builder = client.post(url);

-        let api_key = self.api_key()?;
-        if let Some(key) = api_key {
-            builder = builder.bearer_auth(key);
+        if let Some(auth) = auth.as_ref() {
+            builder = builder.bearer_auth(auth.get_token().await?);
        }

        Ok(self.apply_http_headers(builder))
    }

-    pub(crate) fn get_full_url(&self) -> String {
-        let query_string = self
-            .query_params
+    fn get_query_string(&self) -> String {
+        self.query_params
            .as_ref()
            .map_or_else(String::new, |params| {
                let full_params = params
@@ -115,16 +123,29 @@ impl ModelProviderInfo {
                    .collect::<Vec<_>>()
                    .join("&");
                format!("?{full_params}")
-            });
+            })
+    }
+
+    pub(crate) fn get_full_url(&self, auth: &Option<CodexAuth>) -> String {
+        let default_base_url = if matches!(
+            auth,
+            Some(CodexAuth {
+                mode: AuthMode::ChatGPT,
+                ..
+            })
+        ) {
+            "https://chatgpt.com/backend-api/codex"
+        } else {
+            "https://api.openai.com/v1"
+        };
+        let query_string = self.get_query_string();
        let base_url = self
            .base_url
            .clone()
-            .unwrap_or("https://api.openai.com/v1".to_string());
+            .unwrap_or(default_base_url.to_string());

        match self.wire_api {
-            WireApi::Responses => {
-                format!("{base_url}/responses{query_string}")
-            }
+            WireApi::Responses => format!("{base_url}/responses{query_string}"),
            WireApi::Chat => format!("{base_url}/chat/completions{query_string}"),
        }
    }
@@ -132,10 +153,7 @@ impl ModelProviderInfo {
    /// Apply provider-specific HTTP headers (both static and environment-based)
    /// onto an existing `reqwest::RequestBuilder` and return the updated
    /// builder.
-    pub fn apply_http_headers(
-        &self,
-        mut builder: reqwest::RequestBuilder,
-    ) -> reqwest::RequestBuilder {
+    fn apply_http_headers(&self, mut builder: reqwest::RequestBuilder) -> reqwest::RequestBuilder {
        if let Some(extra) = &self.http_headers {
            for (k, v) in extra {
                builder = builder.header(k, v);
@@ -157,7 +175,7 @@ impl ModelProviderInfo {
    /// If `env_key` is Some, returns the API key for this provider if present
    /// (and non-empty) in the environment. If `env_key` is required but
    /// cannot be found, returns an error.
-    fn api_key(&self) -> crate::error::Result<Option<String>> {
+    pub fn api_key(&self) -> crate::error::Result<Option<String>> {
        match &self.env_key {
            Some(env_key) => {
                let env_value = std::env::var(env_key);
@@ -198,6 +216,14 @@ impl ModelProviderInfo {
            .map(Duration::from_millis)
            .unwrap_or(Duration::from_millis(DEFAULT_STREAM_IDLE_TIMEOUT_MS))
    }
+
+    fn get_fallback_auth(&self) -> crate::error::Result<Option<CodexAuth>> {
+        let api_key = self.api_key()?;
+        if let Some(api_key) = api_key {
+            return Ok(Some(CodexAuth::from_api_key(api_key)));
+        }
+        Ok(None)
+    }
 }

 /// Built-in default provider list.
--- a/codex-rs/core/src/models.rs
+++ b/codex-rs/core/src/models.rs
@@ -9,7 +9,7 @@ use serde::ser::Serializer;

 use crate::protocol::InputItem;

-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum ResponseInputItem {
    Message {
@@ -26,7 +26,7 @@ pub enum ResponseInputItem {
    },
 }

-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum ContentItem {
    InputText { text: String },
@@ -34,7 +34,7 @@ pub enum ContentItem {
    OutputText { text: String },
 }

-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum ResponseItem {
    Message {
@@ -107,7 +107,7 @@ impl From<ResponseInputItem> for ResponseItem {
    }
 }

-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 #[serde(rename_all = "snake_case")]
 pub enum LocalShellStatus {
    Completed,
@@ -115,13 +115,13 @@ pub enum LocalShellStatus {
    Incomplete,
 }

-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum LocalShellAction {
    Exec(LocalShellExecAction),
 }

-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 pub struct LocalShellExecAction {
    pub command: Vec<String>,
    pub timeout_ms: Option<u64>,
@@ -130,7 +130,7 @@ pub struct LocalShellExecAction {
    pub user: Option<String>,
 }

-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum ReasoningItemReasoningSummary {
    SummaryText { text: String },
@@ -185,10 +185,9 @@ pub struct ShellToolCallParams {
    pub timeout_ms: Option<u64>,
 }

-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq)]
 pub struct FunctionCallOutputPayload {
    pub content: String,
-    #[expect(dead_code)]
    pub success: Option<bool>,
 }

--- a/codex-rs/core/src/protocol.rs
+++ b/codex-rs/core/src/protocol.rs
@@ -387,6 +387,8 @@ pub enum EventMsg {
    /// Notification that a patch application has finished.
    PatchApplyEnd(PatchApplyEndEvent),

+    TurnDiff(TurnDiffEvent),
+
    /// Response to GetHistoryEntryRequest.
    GetHistoryEntryResponse(GetHistoryEntryResponseEvent),

@@ -598,6 +600,11 @@ pub struct PatchApplyEndEvent {
    pub success: bool,
 }

+#[derive(Debug, Clone, Deserialize, Serialize)]
+pub struct TurnDiffEvent {
+    pub unified_diff: String,
+}
+
 #[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct GetHistoryEntryResponseEvent {
    pub offset: usize,
--- a/codex-rs/core/src/turn_diff_tracker.rs
+++ b/codex-rs/core/src/turn_diff_tracker.rs
@@ -0,0 +1,887 @@
+use std::collections::HashMap;
+use std::fs;
+use std::path::Path;
+use std::path::PathBuf;
+use std::process::Command;
+
+use anyhow::Context;
+use anyhow::Result;
+use anyhow::anyhow;
+use sha1::digest::Output;
+use uuid::Uuid;
+
+use crate::protocol::FileChange;
+
+const ZERO_OID: &str = "0000000000000000000000000000000000000000";
+const DEV_NULL: &str = "/dev/null";
+
+struct BaselineFileInfo {
+    path: PathBuf,
+    content: Vec<u8>,
+    mode: FileMode,
+    oid: String,
+}
+
+/// Tracks sets of changes to files and exposes the overall unified diff.
+/// Internally, the way this works is now:
+/// 1. Maintain an in-memory baseline snapshot of files when they are first seen.
+///    For new additions, do not create a baseline so that diffs are shown as proper additions (using /dev/null).
+/// 2. Keep a stable internal filename (uuid) per external path for rename tracking.
+/// 3. To compute the aggregated unified diff, compare each baseline snapshot to the current file on disk entirely in-memory
+///    using the `similar` crate and emit unified diffs with rewritten external paths.
+#[derive(Default)]
+pub struct TurnDiffTracker {
+    /// Map external path -> internal filename (uuid).
+    external_to_temp_name: HashMap<PathBuf, String>,
+    /// Internal filename -> baseline file info.
+    baseline_file_info: HashMap<String, BaselineFileInfo>,
+    /// Internal filename -> external path as of current accumulated state (after applying all changes).
+    /// This is where renames are tracked.
+    temp_name_to_current_path: HashMap<String, PathBuf>,
+    /// Cache of known git worktree roots to avoid repeated filesystem walks.
+    git_root_cache: Vec<PathBuf>,
+}
+
+impl TurnDiffTracker {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Front-run apply patch calls to track the starting contents of any modified files.
+    /// - Creates an in-memory baseline snapshot for files that already exist on disk when first seen.
+    /// - For additions, we intentionally do not create a baseline snapshot so that diffs are proper additions.
+    /// - Also updates internal mappings for move/rename events.
+    pub fn on_patch_begin(&mut self, changes: &HashMap<PathBuf, FileChange>) {
+        for (path, change) in changes.iter() {
+            // Ensure a stable internal filename exists for this external path.
+            if !self.external_to_temp_name.contains_key(path) {
+                let internal = Uuid::new_v4().to_string();
+                self.external_to_temp_name
+                    .insert(path.clone(), internal.clone());
+                self.temp_name_to_current_path
+                    .insert(internal.clone(), path.clone());
+
+                // If the file exists on disk now, snapshot as baseline; else leave missing to represent /dev/null.
+                let baseline_file_info = if path.exists() {
+                    let mode = file_mode_for_path(path);
+                    let mode_val = mode.unwrap_or(FileMode::Regular);
+                    let content = blob_bytes(path, &mode_val).unwrap_or_default();
+                    let oid = if mode == Some(FileMode::Symlink) {
+                        format!("{:x}", git_blob_sha1_hex_bytes(&content))
+                    } else {
+                        self.git_blob_oid_for_path(path)
+                            .unwrap_or_else(|| format!("{:x}", git_blob_sha1_hex_bytes(&content)))
+                    };
+                    Some(BaselineFileInfo {
+                        path: path.clone(),
+                        content,
+                        mode: mode_val,
+                        oid,
+                    })
+                } else {
+                    Some(BaselineFileInfo {
+                        path: path.clone(),
+                        content: vec![],
+                        mode: FileMode::Regular,
+                        oid: ZERO_OID.to_string(),
+                    })
+                };
+
+                if let Some(baseline_file_info) = baseline_file_info {
+                    self.baseline_file_info
+                        .insert(internal.clone(), baseline_file_info);
+                }
+            }
+
+            // Track rename/move in current mapping if provided in an Update.
+            if let FileChange::Update {
+                move_path: Some(dest),
+                ..
+            } = change
+            {
+                let uuid_filename = match self.external_to_temp_name.get(path) {
+                    Some(i) => i.clone(),
+                    None => {
+                        // This should be rare, but if we haven't mapped the source, create it with no baseline.
+                        let i = Uuid::new_v4().to_string();
+                        self.baseline_file_info.insert(
+                            i.clone(),
+                            BaselineFileInfo {
+                                path: path.clone(),
+                                content: vec![],
+                                mode: FileMode::Regular,
+                                oid: ZERO_OID.to_string(),
+                            },
+                        );
+                        i
+                    }
+                };
+                // Update current external mapping for temp file name.
+                self.temp_name_to_current_path
+                    .insert(uuid_filename.clone(), dest.clone());
+                // Update forward file_mapping: external current -> internal name.
+                self.external_to_temp_name.remove(path);
+                self.external_to_temp_name
+                    .insert(dest.clone(), uuid_filename);
+            };
+        }
+    }
+
+    fn get_path_for_internal(&self, internal: &str) -> Option<PathBuf> {
+        self.temp_name_to_current_path
+            .get(internal)
+            .cloned()
+            .or_else(|| {
+                self.baseline_file_info
+                    .get(internal)
+                    .map(|info| info.path.clone())
+            })
+    }
+
+    /// Find the git worktree root for a file/directory by walking up to the first ancestor containing a `.git` entry.
+    /// Uses a simple cache of known roots and avoids negative-result caching for simplicity.
+    fn find_git_root_cached(&mut self, start: &Path) -> Option<PathBuf> {
+        let dir = if start.is_dir() {
+            start
+        } else {
+            start.parent()?
+        };
+
+        // Fast path: if any cached root is an ancestor of this path, use it.
+        if let Some(root) = self
+            .git_root_cache
+            .iter()
+            .find(|r| dir.starts_with(r))
+            .cloned()
+        {
+            return Some(root);
+        }
+
+        // Walk up to find a `.git` marker.
+        let mut cur = dir.to_path_buf();
+        loop {
+            let git_marker = cur.join(".git");
+            if git_marker.is_dir() || git_marker.is_file() {
+                if !self.git_root_cache.iter().any(|r| r == &cur) {
+                    self.git_root_cache.push(cur.clone());
+                }
+                return Some(cur);
+            }
+
+            // On Windows, avoid walking above the drive or UNC share root.
+            #[cfg(windows)]
+            {
+                if is_windows_drive_or_unc_root(&cur) {
+                    return None;
+                }
+            }
+
+            if let Some(parent) = cur.parent() {
+                cur = parent.to_path_buf();
+            } else {
+                return None;
+            }
+        }
+    }
+
+    /// Return a display string for `path` relative to its git root if found, else absolute.
+    fn relative_to_git_root_str(&mut self, path: &Path) -> String {
+        let s = if let Some(root) = self.find_git_root_cached(path) {
+            if let Ok(rel) = path.strip_prefix(&root) {
+                rel.display().to_string()
+            } else {
+                path.display().to_string()
+            }
+        } else {
+            path.display().to_string()
+        };
+        s.replace('\\', "/")
+    }
+
+    /// Ask git to compute the blob SHA-1 for the file at `path` within its repository.
+    /// Returns None if no repository is found or git invocation fails.
+    fn git_blob_oid_for_path(&mut self, path: &Path) -> Option<String> {
+        let root = self.find_git_root_cached(path)?;
+        // Compute a path relative to the repo root for better portability across platforms.
+        let rel = path.strip_prefix(&root).unwrap_or(path);
+        let output = Command::new("git")
+            .arg("-C")
+            .arg(&root)
+            .arg("hash-object")
+            .arg("--")
+            .arg(rel)
+            .output()
+            .ok()?;
+        if !output.status.success() {
+            return None;
+        }
+        let s = String::from_utf8_lossy(&output.stdout).trim().to_string();
+        if s.len() == 40 { Some(s) } else { None }
+    }
+
+    /// Recompute the aggregated unified diff by comparing all of the in-memory snapshots that were
+    /// collected before the first time they were touched by apply_patch during this turn with
+    /// the current repo state.
+    pub fn get_unified_diff(&mut self) -> Result<Option<String>> {
+        let mut aggregated = String::new();
+
+        // Compute diffs per tracked internal file in a stable order by external path.
+        let mut baseline_file_names: Vec<String> =
+            self.baseline_file_info.keys().cloned().collect();
+        // Sort lexicographically by full repo-relative path to match git behavior.
+        baseline_file_names.sort_by_key(|internal| {
+            self.get_path_for_internal(internal)
+                .map(|p| self.relative_to_git_root_str(&p))
+                .unwrap_or_default()
+        });
+
+        for internal in baseline_file_names {
+            aggregated.push_str(self.get_file_diff(&internal).as_str());
+            if !aggregated.ends_with('\n') {
+                aggregated.push('\n');
+            }
+        }
+
+        if aggregated.trim().is_empty() {
+            Ok(None)
+        } else {
+            Ok(Some(aggregated))
+        }
+    }
+
+    fn get_file_diff(&mut self, internal_file_name: &str) -> String {
+        let mut aggregated = String::new();
+
+        // Snapshot lightweight fields only.
+        let (baseline_external_path, baseline_mode, left_oid) = {
+            if let Some(info) = self.baseline_file_info.get(internal_file_name) {
+                (info.path.clone(), info.mode, info.oid.clone())
+            } else {
+                (PathBuf::new(), FileMode::Regular, ZERO_OID.to_string())
+            }
+        };
+        let current_external_path = match self.get_path_for_internal(internal_file_name) {
+            Some(p) => p,
+            None => return aggregated,
+        };
+
+        let current_mode = file_mode_for_path(&current_external_path).unwrap_or(FileMode::Regular);
+        let right_bytes = blob_bytes(&current_external_path, &current_mode);
+
+        // Compute displays with &mut self before borrowing any baseline content.
+        let left_display = self.relative_to_git_root_str(&baseline_external_path);
+        let right_display = self.relative_to_git_root_str(&current_external_path);
+
+        // Compute right oid before borrowing baseline content.
+        let right_oid = if let Some(b) = right_bytes.as_ref() {
+            if current_mode == FileMode::Symlink {
+                format!("{:x}", git_blob_sha1_hex_bytes(b))
+            } else {
+                self.git_blob_oid_for_path(&current_external_path)
+                    .unwrap_or_else(|| format!("{:x}", git_blob_sha1_hex_bytes(b)))
+            }
+        } else {
+            ZERO_OID.to_string()
+        };
+
+        // Borrow baseline content only after all &mut self uses are done.
+        let left_present = left_oid.as_str() != ZERO_OID;
+        let left_bytes: Option<&[u8]> = if left_present {
+            self.baseline_file_info
+                .get(internal_file_name)
+                .map(|i| i.content.as_slice())
+        } else {
+            None
+        };
+
+        // Fast path: identical bytes or both missing.
+        if left_bytes == right_bytes.as_deref() {
+            return aggregated;
+        }
+
+        aggregated.push_str(&format!("diff --git a/{left_display} b/{right_display}\n"));
+
+        let is_add = !left_present && right_bytes.is_some();
+        let is_delete = left_present && right_bytes.is_none();
+
+        if is_add {
+            aggregated.push_str(&format!("new file mode {current_mode}\n"));
+        } else if is_delete {
+            aggregated.push_str(&format!("deleted file mode {baseline_mode}\n"));
+        } else if baseline_mode != current_mode {
+            aggregated.push_str(&format!("old mode {baseline_mode}\n"));
+            aggregated.push_str(&format!("new mode {current_mode}\n"));
+        }
+
+        let left_text = left_bytes.and_then(|b| std::str::from_utf8(b).ok());
+        let right_text = right_bytes
+            .as_deref()
+            .and_then(|b| std::str::from_utf8(b).ok());
+
+        let can_text_diff = matches!(
+            (left_text, right_text, is_add, is_delete),
+            (Some(_), Some(_), _, _) | (_, Some(_), true, _) | (Some(_), _, _, true)
+        );
+
+        if can_text_diff {
+            let l = left_text.unwrap_or("");
+            let r = right_text.unwrap_or("");
+
+            aggregated.push_str(&format!("index {left_oid}..{right_oid}\n"));
+
+            let old_header = if left_present {
+                format!("a/{left_display}")
+            } else {
+                DEV_NULL.to_string()
+            };
+            let new_header = if right_bytes.is_some() {
+                format!("b/{right_display}")
+            } else {
+                DEV_NULL.to_string()
+            };
+
+            let diff = similar::TextDiff::from_lines(l, r);
+            let unified = diff
+                .unified_diff()
+                .context_radius(3)
+                .header(&old_header, &new_header)
+                .to_string();
+
+            aggregated.push_str(&unified);
+        } else {
+            aggregated.push_str(&format!("index {left_oid}..{right_oid}\n"));
+            let old_header = if left_present {
+                format!("a/{left_display}")
+            } else {
+                DEV_NULL.to_string()
+            };
+            let new_header = if right_bytes.is_some() {
+                format!("b/{right_display}")
+            } else {
+                DEV_NULL.to_string()
+            };
+            aggregated.push_str(&format!("--- {old_header}\n"));
+            aggregated.push_str(&format!("+++ {new_header}\n"));
+            aggregated.push_str("Binary files differ\n");
+        }
+        aggregated
+    }
+}
+
+/// Compute the Git SHA-1 blob object ID for the given content (bytes).
+fn git_blob_sha1_hex_bytes(data: &[u8]) -> Output<sha1::Sha1> {
+    // Git blob hash is sha1 of: "blob <len>\0<data>"
+    let header = format!("blob {}\0", data.len());
+    use sha1::Digest;
+    let mut hasher = sha1::Sha1::new();
+    hasher.update(header.as_bytes());
+    hasher.update(data);
+    hasher.finalize()
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+enum FileMode {
+    Regular,
+    #[cfg(unix)]
+    Executable,
+    Symlink,
+}
+
+impl FileMode {
+    fn as_str(&self) -> &'static str {
+        match self {
+            FileMode::Regular => "100644",
+            #[cfg(unix)]
+            FileMode::Executable => "100755",
+            FileMode::Symlink => "120000",
+        }
+    }
+}
+
+impl std::fmt::Display for FileMode {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(self.as_str())
+    }
+}
+
+#[cfg(unix)]
+fn file_mode_for_path(path: &Path) -> Option<FileMode> {
+    use std::os::unix::fs::PermissionsExt;
+    let meta = fs::symlink_metadata(path).ok()?;
+    let ft = meta.file_type();
+    if ft.is_symlink() {
+        return Some(FileMode::Symlink);
+    }
+    let mode = meta.permissions().mode();
+    let is_exec = (mode & 0o111) != 0;
+    Some(if is_exec {
+        FileMode::Executable
+    } else {
+        FileMode::Regular
+    })
+}
+
+#[cfg(not(unix))]
+fn file_mode_for_path(_path: &Path) -> Option<FileMode> {
+    // Default to non-executable on non-unix.
+    Some(FileMode::Regular)
+}
+
+fn blob_bytes(path: &Path, mode: &FileMode) -> Option<Vec<u8>> {
+    if path.exists() {
+        let contents = if *mode == FileMode::Symlink {
+            symlink_blob_bytes(path)
+                .ok_or_else(|| anyhow!("failed to read symlink target for {}", path.display()))
+        } else {
+            fs::read(path)
+                .with_context(|| format!("failed to read current file for diff {}", path.display()))
+        };
+        contents.ok()
+    } else {
+        None
+    }
+}
+
+#[cfg(unix)]
+fn symlink_blob_bytes(path: &Path) -> Option<Vec<u8>> {
+    use std::os::unix::ffi::OsStrExt;
+    let target = std::fs::read_link(path).ok()?;
+    Some(target.as_os_str().as_bytes().to_vec())
+}
+
+#[cfg(not(unix))]
+fn symlink_blob_bytes(_path: &Path) -> Option<Vec<u8>> {
+    None
+}
+
+#[cfg(windows)]
+fn is_windows_drive_or_unc_root(p: &std::path::Path) -> bool {
+    use std::path::Component;
+    let mut comps = p.components();
+    matches!(
+        (comps.next(), comps.next(), comps.next()),
+        (Some(Component::Prefix(_)), Some(Component::RootDir), None)
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    #![allow(clippy::unwrap_used)]
+    use super::*;
+    use pretty_assertions::assert_eq;
+    use tempfile::tempdir;
+
+    /// Compute the Git SHA-1 blob object ID for the given content (string).
+    /// This delegates to the bytes version to avoid UTF-8 lossy conversions here.
+    fn git_blob_sha1_hex(data: &str) -> String {
+        format!("{:x}", git_blob_sha1_hex_bytes(data.as_bytes()))
+    }
+
+    fn normalize_diff_for_test(input: &str, root: &Path) -> String {
+        let root_str = root.display().to_string().replace('\\', "/");
+        let replaced = input.replace(&root_str, "<TMP>");
+        // Split into blocks on lines starting with "diff --git ", sort blocks for determinism, and rejoin
+        let mut blocks: Vec<String> = Vec::new();
+        let mut current = String::new();
+        for line in replaced.lines() {
+            if line.starts_with("diff --git ") && !current.is_empty() {
+                blocks.push(current);
+                current = String::new();
+            }
+            if !current.is_empty() {
+                current.push('\n');
+            }
+            current.push_str(line);
+        }
+        if !current.is_empty() {
+            blocks.push(current);
+        }
+        blocks.sort();
+        let mut out = blocks.join("\n");
+        if !out.ends_with('\n') {
+            out.push('\n');
+        }
+        out
+    }
+
+    #[test]
+    fn accumulates_add_and_update() {
+        let mut acc = TurnDiffTracker::new();
+
+        let dir = tempdir().unwrap();
+        let file = dir.path().join("a.txt");
+
+        // First patch: add file (baseline should be /dev/null).
+        let add_changes = HashMap::from([(
+            file.clone(),
+            FileChange::Add {
+                content: "foo\n".to_string(),
+            },
+        )]);
+        acc.on_patch_begin(&add_changes);
+
+        // Simulate apply: create the file on disk.
+        fs::write(&file, "foo\n").unwrap();
+        let first = acc.get_unified_diff().unwrap().unwrap();
+        let first = normalize_diff_for_test(&first, dir.path());
+        let expected_first = {
+            let mode = file_mode_for_path(&file).unwrap_or(FileMode::Regular);
+            let right_oid = git_blob_sha1_hex("foo\n");
+            format!(
+                r#"diff --git a/<TMP>/a.txt b/<TMP>/a.txt
+new file mode {mode}
+index {ZERO_OID}..{right_oid}
+--- {DEV_NULL}
+++ b/<TMP>/a.txt
+@@ -0,0 +1 @@
+foo
+"#,
+            )
+        };
+        assert_eq!(first, expected_first);
+
+        // Second patch: update the file on disk.
+        let update_changes = HashMap::from([(
+            file.clone(),
+            FileChange::Update {
+                unified_diff: "".to_owned(),
+                move_path: None,
+            },
+        )]);
+        acc.on_patch_begin(&update_changes);
+
+        // Simulate apply: append a new line.
+        fs::write(&file, "foo\nbar\n").unwrap();
+        let combined = acc.get_unified_diff().unwrap().unwrap();
+        let combined = normalize_diff_for_test(&combined, dir.path());
+        let expected_combined = {
+            let mode = file_mode_for_path(&file).unwrap_or(FileMode::Regular);
+            let right_oid = git_blob_sha1_hex("foo\nbar\n");
+            format!(
+                r#"diff --git a/<TMP>/a.txt b/<TMP>/a.txt
+new file mode {mode}
+index {ZERO_OID}..{right_oid}
+--- {DEV_NULL}
+++ b/<TMP>/a.txt
+@@ -0,0 +1,2 @@
+foo
+bar
+"#,
+            )
+        };
+        assert_eq!(combined, expected_combined);
+    }
+
+    #[test]
+    fn accumulates_delete() {
+        let dir = tempdir().unwrap();
+        let file = dir.path().join("b.txt");
+        fs::write(&file, "x\n").unwrap();
+
+        let mut acc = TurnDiffTracker::new();
+        let del_changes = HashMap::from([(file.clone(), FileChange::Delete)]);
+        acc.on_patch_begin(&del_changes);
+
+        // Simulate apply: delete the file from disk.
+        let baseline_mode = file_mode_for_path(&file).unwrap_or(FileMode::Regular);
+        fs::remove_file(&file).unwrap();
+        let diff = acc.get_unified_diff().unwrap().unwrap();
+        let diff = normalize_diff_for_test(&diff, dir.path());
+        let expected = {
+            let left_oid = git_blob_sha1_hex("x\n");
+            format!(
+                r#"diff --git a/<TMP>/b.txt b/<TMP>/b.txt
+deleted file mode {baseline_mode}
+index {left_oid}..{ZERO_OID}
+--- a/<TMP>/b.txt
+++ {DEV_NULL}
+@@ -1 +0,0 @@
+-x
+"#,
+            )
+        };
+        assert_eq!(diff, expected);
+    }
+
+    #[test]
+    fn accumulates_move_and_update() {
+        let dir = tempdir().unwrap();
+        let src = dir.path().join("src.txt");
+        let dest = dir.path().join("dst.txt");
+        fs::write(&src, "line\n").unwrap();
+
+        let mut acc = TurnDiffTracker::new();
+        let mv_changes = HashMap::from([(
+            src.clone(),
+            FileChange::Update {
+                unified_diff: "".to_owned(),
+                move_path: Some(dest.clone()),
+            },
+        )]);
+        acc.on_patch_begin(&mv_changes);
+
+        // Simulate apply: move and update content.
+        fs::rename(&src, &dest).unwrap();
+        fs::write(&dest, "line2\n").unwrap();
+
+        let out = acc.get_unified_diff().unwrap().unwrap();
+        let out = normalize_diff_for_test(&out, dir.path());
+        let expected = {
+            let left_oid = git_blob_sha1_hex("line\n");
+            let right_oid = git_blob_sha1_hex("line2\n");
+            format!(
+                r#"diff --git a/<TMP>/src.txt b/<TMP>/dst.txt
+index {left_oid}..{right_oid}
+--- a/<TMP>/src.txt
+++ b/<TMP>/dst.txt
+@@ -1 +1 @@
+-line
+line2
+"#
+            )
+        };
+        assert_eq!(out, expected);
+    }
+
+    #[test]
+    fn move_without_1change_yields_no_diff() {
+        let dir = tempdir().unwrap();
+        let src = dir.path().join("moved.txt");
+        let dest = dir.path().join("renamed.txt");
+        fs::write(&src, "same\n").unwrap();
+
+        let mut acc = TurnDiffTracker::new();
+        let mv_changes = HashMap::from([(
+            src.clone(),
+            FileChange::Update {
+                unified_diff: "".to_owned(),
+                move_path: Some(dest.clone()),
+            },
+        )]);
+        acc.on_patch_begin(&mv_changes);
+
+        // Simulate apply: move only, no content change.
+        fs::rename(&src, &dest).unwrap();
+
+        let diff = acc.get_unified_diff().unwrap();
+        assert_eq!(diff, None);
+    }
+
+    #[test]
+    fn move_declared_but_file_only_appears_at_dest_is_add() {
+        let dir = tempdir().unwrap();
+        let src = dir.path().join("src.txt");
+        let dest = dir.path().join("dest.txt");
+        let mut acc = TurnDiffTracker::new();
+        let mv = HashMap::from([(
+            src.clone(),
+            FileChange::Update {
+                unified_diff: "".into(),
+                move_path: Some(dest.clone()),
+            },
+        )]);
+        acc.on_patch_begin(&mv);
+        // No file existed initially; create only dest
+        fs::write(&dest, "hello\n").unwrap();
+        let diff = acc.get_unified_diff().unwrap().unwrap();
+        let diff = normalize_diff_for_test(&diff, dir.path());
+        let expected = {
+            let mode = file_mode_for_path(&dest).unwrap_or(FileMode::Regular);
+            let right_oid = git_blob_sha1_hex("hello\n");
+            format!(
+                r#"diff --git a/<TMP>/src.txt b/<TMP>/dest.txt
+new file mode {mode}
+index {ZERO_OID}..{right_oid}
+--- {DEV_NULL}
+++ b/<TMP>/dest.txt
+@@ -0,0 +1 @@
+hello
+"#,
+            )
+        };
+        assert_eq!(diff, expected);
+    }
+
+    #[test]
+    fn update_persists_across_new_baseline_for_new_file() {
+        let dir = tempdir().unwrap();
+        let a = dir.path().join("a.txt");
+        let b = dir.path().join("b.txt");
+        fs::write(&a, "foo\n").unwrap();
+        fs::write(&b, "z\n").unwrap();
+
+        let mut acc = TurnDiffTracker::new();
+
+        // First: update existing a.txt (baseline snapshot is created for a).
+        let update_a = HashMap::from([(
+            a.clone(),
+            FileChange::Update {
+                unified_diff: "".to_owned(),
+                move_path: None,
+            },
+        )]);
+        acc.on_patch_begin(&update_a);
+        // Simulate apply: modify a.txt on disk.
+        fs::write(&a, "foo\nbar\n").unwrap();
+        let first = acc.get_unified_diff().unwrap().unwrap();
+        let first = normalize_diff_for_test(&first, dir.path());
+        let expected_first = {
+            let left_oid = git_blob_sha1_hex("foo\n");
+            let right_oid = git_blob_sha1_hex("foo\nbar\n");
+            format!(
+                r#"diff --git a/<TMP>/a.txt b/<TMP>/a.txt
+index {left_oid}..{right_oid}
+--- a/<TMP>/a.txt
+++ b/<TMP>/a.txt
+@@ -1 +1,2 @@
+ foo
+bar
+"#
+            )
+        };
+        assert_eq!(first, expected_first);
+
+        // Next: introduce a brand-new path b.txt into baseline snapshots via a delete change.
+        let del_b = HashMap::from([(b.clone(), FileChange::Delete)]);
+        acc.on_patch_begin(&del_b);
+        // Simulate apply: delete b.txt.
+        let baseline_mode = file_mode_for_path(&b).unwrap_or(FileMode::Regular);
+        fs::remove_file(&b).unwrap();
+
+        let combined = acc.get_unified_diff().unwrap().unwrap();
+        let combined = normalize_diff_for_test(&combined, dir.path());
+        let expected = {
+            let left_oid_a = git_blob_sha1_hex("foo\n");
+            let right_oid_a = git_blob_sha1_hex("foo\nbar\n");
+            let left_oid_b = git_blob_sha1_hex("z\n");
+            format!(
+                r#"diff --git a/<TMP>/a.txt b/<TMP>/a.txt
+index {left_oid_a}..{right_oid_a}
+--- a/<TMP>/a.txt
+++ b/<TMP>/a.txt
+@@ -1 +1,2 @@
+ foo
+bar
+diff --git a/<TMP>/b.txt b/<TMP>/b.txt
+deleted file mode {baseline_mode}
+index {left_oid_b}..{ZERO_OID}
+--- a/<TMP>/b.txt
+++ {DEV_NULL}
+@@ -1 +0,0 @@
+-z
+"#,
+            )
+        };
+        assert_eq!(combined, expected);
+    }
+
+    #[test]
+    fn binary_files_differ_update() {
+        let dir = tempdir().unwrap();
+        let file = dir.path().join("bin.dat");
+
+        // Initial non-UTF8 bytes
+        let left_bytes: Vec<u8> = vec![0xff, 0xfe, 0xfd, 0x00];
+        // Updated non-UTF8 bytes
+        let right_bytes: Vec<u8> = vec![0x01, 0x02, 0x03, 0x00];
+
+        fs::write(&file, &left_bytes).unwrap();
+
+        let mut acc = TurnDiffTracker::new();
+        let update_changes = HashMap::from([(
+            file.clone(),
+            FileChange::Update {
+                unified_diff: "".to_owned(),
+                move_path: None,
+            },
+        )]);
+        acc.on_patch_begin(&update_changes);
+
+        // Apply update on disk
+        fs::write(&file, &right_bytes).unwrap();
+
+        let diff = acc.get_unified_diff().unwrap().unwrap();
+        let diff = normalize_diff_for_test(&diff, dir.path());
+        let expected = {
+            let left_oid = format!("{:x}", git_blob_sha1_hex_bytes(&left_bytes));
+            let right_oid = format!("{:x}", git_blob_sha1_hex_bytes(&right_bytes));
+            format!(
+                r#"diff --git a/<TMP>/bin.dat b/<TMP>/bin.dat
+index {left_oid}..{right_oid}
+--- a/<TMP>/bin.dat
+++ b/<TMP>/bin.dat
+Binary files differ
+"#
+            )
+        };
+        assert_eq!(diff, expected);
+    }
+
+    #[test]
+    fn filenames_with_spaces_add_and_update() {
+        let mut acc = TurnDiffTracker::new();
+
+        let dir = tempdir().unwrap();
+        let file = dir.path().join("name with spaces.txt");
+
+        // First patch: add file (baseline should be /dev/null).
+        let add_changes = HashMap::from([(
+            file.clone(),
+            FileChange::Add {
+                content: "foo\n".to_string(),
+            },
+        )]);
+        acc.on_patch_begin(&add_changes);
+
+        // Simulate apply: create the file on disk.
+        fs::write(&file, "foo\n").unwrap();
+        let first = acc.get_unified_diff().unwrap().unwrap();
+        let first = normalize_diff_for_test(&first, dir.path());
+        let expected_first = {
+            let mode = file_mode_for_path(&file).unwrap_or(FileMode::Regular);
+            let right_oid = git_blob_sha1_hex("foo\n");
+            format!(
+                r#"diff --git a/<TMP>/name with spaces.txt b/<TMP>/name with spaces.txt
+new file mode {mode}
+index {ZERO_OID}..{right_oid}
+--- {DEV_NULL}
+++ b/<TMP>/name with spaces.txt
+@@ -0,0 +1 @@
+foo
+"#,
+            )
+        };
+        assert_eq!(first, expected_first);
+
+        // Second patch: update the file on disk.
+        let update_changes = HashMap::from([(
+            file.clone(),
+            FileChange::Update {
+                unified_diff: "".to_owned(),
+                move_path: None,
+            },
+        )]);
+        acc.on_patch_begin(&update_changes);
+
+        // Simulate apply: append a new line with a space.
+        fs::write(&file, "foo\nbar baz\n").unwrap();
+        let combined = acc.get_unified_diff().unwrap().unwrap();
+        let combined = normalize_diff_for_test(&combined, dir.path());
+        let expected_combined = {
+            let mode = file_mode_for_path(&file).unwrap_or(FileMode::Regular);
+            let right_oid = git_blob_sha1_hex("foo\nbar baz\n");
+            format!(
+                r#"diff --git a/<TMP>/name with spaces.txt b/<TMP>/name with spaces.txt
+new file mode {mode}
+index {ZERO_OID}..{right_oid}
+--- {DEV_NULL}
+++ b/<TMP>/name with spaces.txt
+@@ -0,0 +1,2 @@
+foo
+bar baz
+"#,
+            )
+        };
+        assert_eq!(combined, expected_combined);
+    }
+}
--- a/codex-rs/core/tests/client.rs
+++ b/codex-rs/core/tests/client.rs
@@ -4,6 +4,7 @@ use chrono::Utc;
 use codex_core::Codex;
 use codex_core::CodexSpawnOk;
 use codex_core::ModelProviderInfo;
+use codex_core::WireApi;
 use codex_core::built_in_model_providers;
 use codex_core::protocol::EventMsg;
 use codex_core::protocol::InputItem;
@@ -21,8 +22,10 @@ use tempfile::TempDir;
 use wiremock::Mock;
 use wiremock::MockServer;
 use wiremock::ResponseTemplate;
+use wiremock::matchers::header_regex;
 use wiremock::matchers::method;
 use wiremock::matchers::path;
+use wiremock::matchers::query_param;

 /// Build minimal SSE stream with completed marker using the JSON fixture.
 fn sse_completed(id: &str) -> String {
@@ -373,9 +376,90 @@ async fn includes_user_instructions_message_in_request() {
        request_body["input"][0]["content"][0]["text"]
            .as_str()
            .unwrap()
-            .starts_with("be nice")
+            .starts_with("<user_instructions>\n\nbe nice")
+    );
+    assert!(
+        request_body["input"][0]["content"][0]["text"]
+            .as_str()
+            .unwrap()
+            .ends_with("</user_instructions>")
    );
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn azure_overrides_assign_properties_used_for_responses_url() {
+    #![allow(clippy::unwrap_used)]
+
+    let existing_env_var_with_random_value = if cfg!(windows) { "USERNAME" } else { "USER" };
+
+    // Mock server
+    let server = MockServer::start().await;
+
+    // First request – must NOT include `previous_response_id`.
+    let first = ResponseTemplate::new(200)
+        .insert_header("content-type", "text/event-stream")
+        .set_body_raw(sse_completed("resp1"), "text/event-stream");
+
+    // Expect POST to /openai/responses with api-version query param
+    Mock::given(method("POST"))
+        .and(path("/openai/responses"))
+        .and(query_param("api-version", "2025-04-01-preview"))
+        .and(header_regex("Custom-Header", "Value"))
+        .and(header_regex(
+            "Authorization",
+            format!(
+                "Bearer {}",
+                std::env::var(existing_env_var_with_random_value).unwrap()
+            )
+            .as_str(),
+        ))
+        .respond_with(first)
+        .expect(1)
+        .mount(&server)
+        .await;
+
+    let provider = ModelProviderInfo {
+        name: "custom".to_string(),
+        base_url: Some(format!("{}/openai", server.uri())),
+        // Reuse the existing environment variable to avoid using unsafe code
+        env_key: Some(existing_env_var_with_random_value.to_string()),
+        query_params: Some(std::collections::HashMap::from([(
+            "api-version".to_string(),
+            "2025-04-01-preview".to_string(),
+        )])),
+        env_key_instructions: None,
+        wire_api: WireApi::Responses,
+        http_headers: Some(std::collections::HashMap::from([(
+            "Custom-Header".to_string(),
+            "Value".to_string(),
+        )])),
+        env_http_headers: None,
+        request_max_retries: None,
+        stream_max_retries: None,
+        stream_idle_timeout_ms: None,
+        requires_auth: false,
+    };
+
+    // Init session
+    let codex_home = TempDir::new().unwrap();
+    let mut config = load_default_config_for_test(&codex_home);
+    config.model_provider = provider;
+
+    let ctrl_c = std::sync::Arc::new(tokio::sync::Notify::new());
+    let CodexSpawnOk { codex, .. } = Codex::spawn(config, None, ctrl_c.clone()).await.unwrap();
+
+    codex
+        .submit(Op::UserInput {
+            items: vec![InputItem::Text {
+                text: "hello".into(),
+            }],
+        })
+        .await
+        .unwrap();
+
+    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;
+}
+
 fn auth_from_token(id_token: String) -> CodexAuth {
    CodexAuth::new(
        None,
--- a/codex-rs/core/tests/exec.rs
+++ b/codex-rs/core/tests/exec.rs
@@ -0,0 +1,69 @@
+#![cfg(target_os = "macos")]
+#![expect(clippy::expect_used)]
+
+use std::collections::HashMap;
+use std::sync::Arc;
+
+use codex_core::exec::ExecParams;
+use codex_core::exec::SandboxType;
+use codex_core::exec::process_exec_tool_call;
+use codex_core::protocol::SandboxPolicy;
+use codex_core::spawn::CODEX_SANDBOX_ENV_VAR;
+use tempfile::TempDir;
+use tokio::sync::Notify;
+
+use codex_core::get_platform_sandbox;
+
+async fn run_test_cmd(tmp: TempDir, cmd: Vec<&str>, should_be_ok: bool) {
+    if std::env::var(CODEX_SANDBOX_ENV_VAR) == Ok("seatbelt".to_string()) {
+        eprintln!("{CODEX_SANDBOX_ENV_VAR} is set to 'seatbelt', skipping test.");
+        return;
+    }
+
+    let sandbox_type = get_platform_sandbox().expect("should be able to get sandbox type");
+    assert_eq!(sandbox_type, SandboxType::MacosSeatbelt);
+
+    let params = ExecParams {
+        command: cmd.iter().map(|s| s.to_string()).collect(),
+        cwd: tmp.path().to_path_buf(),
+        timeout_ms: Some(1000),
+        env: HashMap::new(),
+    };
+
+    let ctrl_c = Arc::new(Notify::new());
+    let policy = SandboxPolicy::new_read_only_policy();
+
+    let result = process_exec_tool_call(params, sandbox_type, ctrl_c, &policy, &None, None).await;
+
+    assert!(result.is_ok() == should_be_ok);
+}
+
+/// Command succeeds with exit code 0 normally
+#[tokio::test]
+async fn exit_code_0_succeeds() {
+    let tmp = TempDir::new().expect("should be able to create temp dir");
+    let cmd = vec!["echo", "hello"];
+
+    run_test_cmd(tmp, cmd, true).await
+}
+
+/// Command not found returns exit code 127, this is not considered a sandbox error
+#[tokio::test]
+async fn exit_command_not_found_is_ok() {
+    let tmp = TempDir::new().expect("should be able to create temp dir");
+    let cmd = vec!["/bin/bash", "-c", "nonexistent_command_12345"];
+    run_test_cmd(tmp, cmd, true).await
+}
+
+/// Writing a file fails and should be considered a sandbox error
+#[tokio::test]
+async fn write_file_fails_as_sandbox_error() {
+    let tmp = TempDir::new().expect("should be able to create temp dir");
+    let path = tmp.path().join("test.txt");
+    let cmd = vec![
+        "/user/bin/touch",
+        path.to_str().expect("should be able to get path"),
+    ];
+
+    run_test_cmd(tmp, cmd, false).await;
+}
--- a/codex-rs/exec/src/event_processor.rs
+++ b/codex-rs/exec/src/event_processor.rs
@@ -44,20 +44,14 @@ pub(crate) fn create_config_summary_entries(config: &Config) -> Vec<(&'static st
    entries
 }

-pub(crate) fn handle_last_message(
-    last_agent_message: Option<&str>,
-    last_message_path: Option<&Path>,
-) {
-    match (last_message_path, last_agent_message) {
-        (Some(path), Some(msg)) => write_last_message_file(msg, Some(path)),
-        (Some(path), None) => {
-            write_last_message_file("", Some(path));
-            eprintln!(
-                "Warning: no last agent message; wrote empty content to {}",
-                path.display()
-            );
-        }
-        (None, _) => eprintln!("Warning: no file to write last message to."),
+pub(crate) fn handle_last_message(last_agent_message: Option<&str>, output_file: &Path) {
+    let message = last_agent_message.unwrap_or_default();
+    write_last_message_file(message, Some(output_file));
+    if last_agent_message.is_none() {
+        eprintln!(
+            "Warning: no last agent message; wrote empty content to {}",
+            output_file.display()
+        );
    }
 }

--- a/codex-rs/exec/src/event_processor_with_human_output.rs
+++ b/codex-rs/exec/src/event_processor_with_human_output.rs
@@ -20,6 +20,7 @@ use codex_core::protocol::PatchApplyEndEvent;
 use codex_core::protocol::SessionConfiguredEvent;
 use codex_core::protocol::TaskCompleteEvent;
 use codex_core::protocol::TokenUsage;
+use codex_core::protocol::TurnDiffEvent;
 use owo_colors::OwoColorize;
 use owo_colors::Style;
 use shlex::try_join;
@@ -169,10 +170,9 @@ impl EventProcessor for EventProcessorWithHumanOutput {
                // Ignore.
            }
            EventMsg::TaskComplete(TaskCompleteEvent { last_agent_message }) => {
-                handle_last_message(
-                    last_agent_message.as_deref(),
-                    self.last_message_path.as_deref(),
-                );
+                if let Some(output_file) = self.last_message_path.as_deref() {
+                    handle_last_message(last_agent_message.as_deref(), output_file);
+                }
                return CodexStatus::InitiateShutdown;
            }
            EventMsg::TokenCount(TokenUsage { total_tokens, .. }) => {
@@ -399,6 +399,7 @@ impl EventProcessor for EventProcessorWithHumanOutput {
                stdout,
                stderr,
                success,
+                ..
            }) => {
                let patch_begin = self.call_id_to_patch.remove(&call_id);

@@ -428,6 +429,10 @@ impl EventProcessor for EventProcessorWithHumanOutput {
                    println!("{}", line.style(self.dimmed));
                }
            }
+            EventMsg::TurnDiff(TurnDiffEvent { unified_diff }) => {
+                ts_println!(self, "{}", "turn diff:".style(self.magenta));
+                println!("{unified_diff}");
+            }
            EventMsg::ExecApprovalRequest(_) => {
                // Should we exit?
            }
--- a/codex-rs/exec/src/event_processor_with_json_output.rs
+++ b/codex-rs/exec/src/event_processor_with_json_output.rs
@@ -46,10 +46,9 @@ impl EventProcessor for EventProcessorWithJsonOutput {
                CodexStatus::Running
            }
            EventMsg::TaskComplete(TaskCompleteEvent { last_agent_message }) => {
-                handle_last_message(
-                    last_agent_message.as_deref(),
-                    self.last_message_path.as_deref(),
-                );
+                if let Some(output_file) = self.last_message_path.as_deref() {
+                    handle_last_message(last_agent_message.as_deref(), output_file);
+                }
                CodexStatus::InitiateShutdown
            }
            EventMsg::ShutdownComplete => CodexStatus::Shutdown,
--- a/codex-rs/execpolicy/Cargo.toml
+++ b/codex-rs/execpolicy/Cargo.toml
@@ -26,7 +26,7 @@ multimap = "0.10.0"
 path-absolutize = "3.1.1"
 regex-lite = "0.1"
 serde = { version = "1.0.194", features = ["derive"] }
-serde_json = "1.0.110"
+serde_json = "1.0.142"
 serde_with = { version = "3", features = ["macros"] }

 [dev-dependencies]
--- a/codex-rs/file-search/Cargo.toml
+++ b/codex-rs/file-search/Cargo.toml
@@ -17,5 +17,5 @@ clap = { version = "4", features = ["derive"] }
 ignore = "0.4.23"
 nucleo-matcher = "0.3.1"
 serde = { version = "1", features = ["derive"] }
-serde_json = "1.0.110"
+serde_json = "1.0.142"
 tokio = { version = "1", features = ["full"] }
--- a/codex-rs/login/src/lib.rs
+++ b/codex-rs/login/src/lib.rs
@@ -22,7 +22,7 @@ const SOURCE_FOR_PYTHON_SERVER: &str = include_str!("./login_with_chatgpt.py");
 const CLIENT_ID: &str = "app_EMoamEEZ73f0CkXaXp7hrann";
 pub const OPENAI_API_KEY_ENV_VAR: &str = "OPENAI_API_KEY";

-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Copy)]
 pub enum AuthMode {
    ApiKey,
    ChatGPT,
--- a/codex-rs/login/src/login_with_chatgpt.py
+++ b/codex-rs/login/src/login_with_chatgpt.py
@@ -458,6 +458,7 @@ class _ApiKeyHTTPServer(http.server.HTTPServer):
            "code_challenge": self.pkce.code_challenge,
            "code_challenge_method": "S256",
            "id_token_add_organizations": "true",
+            "codex_cli_simplified_flow": "true",
            "state": self.state,
        }
        return f"{self.issuer}/oauth/authorize?" + urllib.parse.urlencode(params)
--- a/codex-rs/mcp-server/src/codex_tool_runner.rs
+++ b/codex-rs/mcp-server/src/codex_tool_runner.rs
@@ -263,6 +263,7 @@ async fn run_codex_tool_session_inner(
                    | EventMsg::BackgroundEvent(_)
                    | EventMsg::PatchApplyBegin(_)
                    | EventMsg::PatchApplyEnd(_)
+                    | EventMsg::TurnDiff(_)
                    | EventMsg::GetHistoryEntryResponse(_)
                    | EventMsg::PlanUpdate(_)
                    | EventMsg::ShutdownComplete => {
--- a/codex-rs/mcp-server/src/conversation_loop.rs
+++ b/codex-rs/mcp-server/src/conversation_loop.rs
@@ -97,6 +97,7 @@ pub async fn run_conversation_loop(
                    | EventMsg::McpToolCallEnd(_)
                    | EventMsg::ExecCommandBegin(_)
                    | EventMsg::ExecCommandEnd(_)
+                    | EventMsg::TurnDiff(_)
                    | EventMsg::BackgroundEvent(_)
                    | EventMsg::ExecCommandOutputDelta(_)
                    | EventMsg::PatchApplyBegin(_)
--- a/codex-rs/tui/Cargo.toml
+++ b/codex-rs/tui/Cargo.toml
@@ -11,6 +11,10 @@ path = "src/main.rs"
 name = "codex_tui"
 path = "src/lib.rs"

+[features]
+# Enable vt100-based tests (emulator) when running with `--features vt100-tests`.
+vt100-tests = []
+
 [lints]
 workspace = true

@@ -73,3 +77,4 @@ insta = "1.43.1"
 pretty_assertions = "1"
 rand = "0.8"
 chrono = { version = "0.4", features = ["serde"] }
+vt100 = "0.16.2"
--- a/codex-rs/tui/src/bottom_pane/live_ring_widget.rs
+++ b/codex-rs/tui/src/bottom_pane/live_ring_widget.rs
@@ -0,0 +1,45 @@
+use ratatui::buffer::Buffer;
+use ratatui::layout::Rect;
+use ratatui::text::Line;
+use ratatui::widgets::Paragraph;
+use ratatui::widgets::WidgetRef;
+
+/// Minimal rendering-only widget for the transient ring rows.
+pub(crate) struct LiveRingWidget {
+    max_rows: u16,
+    rows: Vec<Line<'static>>, // newest at the end
+}
+
+impl LiveRingWidget {
+    pub fn new() -> Self {
+        Self {
+            max_rows: 3,
+            rows: Vec::new(),
+        }
+    }
+
+    pub fn set_max_rows(&mut self, n: u16) {
+        self.max_rows = n.max(1);
+    }
+
+    pub fn set_rows(&mut self, rows: Vec<Line<'static>>) {
+        self.rows = rows;
+    }
+
+    pub fn desired_height(&self, _width: u16) -> u16 {
+        let len = self.rows.len() as u16;
+        len.min(self.max_rows)
+    }
+}
+
+impl WidgetRef for LiveRingWidget {
+    fn render_ref(&self, area: Rect, buf: &mut Buffer) {
+        if area.height == 0 {
+            return;
+        }
+        let visible = self.rows.len().saturating_sub(self.max_rows as usize);
+        let slice = &self.rows[visible..];
+        let para = Paragraph::new(slice.to_vec());
+        para.render_ref(area, buf);
+    }
+}
--- a/codex-rs/tui/src/bottom_pane/mod.rs
+++ b/codex-rs/tui/src/bottom_pane/mod.rs
@@ -4,12 +4,12 @@ use crate::app_event::AppEvent;
 use crate::app_event_sender::AppEventSender;
 use crate::user_approval_widget::ApprovalRequest;
 use bottom_pane_view::BottomPaneView;
-use bottom_pane_view::ConditionalUpdate;
 use codex_core::protocol::TokenUsage;
 use codex_file_search::FileMatch;
 use crossterm::event::KeyEvent;
 use ratatui::buffer::Buffer;
 use ratatui::layout::Rect;
+use ratatui::text::Line;
 use ratatui::widgets::WidgetRef;

 mod approval_modal_view;
@@ -18,6 +18,7 @@ mod chat_composer;
 mod chat_composer_history;
 mod command_popup;
 mod file_search_popup;
+mod live_ring_widget;
 mod status_indicator_view;
 mod textarea;

@@ -30,6 +31,7 @@ pub(crate) enum CancellationEvent {
 pub(crate) use chat_composer::ChatComposer;
 pub(crate) use chat_composer::InputResult;

+use crate::status_indicator_widget::StatusIndicatorWidget;
 use approval_modal_view::ApprovalModalView;
 use status_indicator_view::StatusIndicatorView;

@@ -46,6 +48,19 @@ pub(crate) struct BottomPane<'a> {
    has_input_focus: bool,
    is_task_running: bool,
    ctrl_c_quit_hint: bool,
+
+    /// Optional live, multi‑line status/"live cell" rendered directly above
+    /// the composer while a task is running. Unlike `active_view`, this does
+    /// not replace the composer; it augments it.
+    live_status: Option<StatusIndicatorWidget>,
+
+    /// Optional transient ring shown above the composer. This is a rendering-only
+    /// container used during development before we wire it to ChatWidget events.
+    live_ring: Option<live_ring_widget::LiveRingWidget>,
+
+    /// True if the active view is the StatusIndicatorView that replaces the
+    /// composer during a running task.
+    status_view_active: bool,
 }

 pub(crate) struct BottomPaneParams {
@@ -55,6 +70,7 @@ pub(crate) struct BottomPaneParams {
 }

 impl BottomPane<'_> {
+    const BOTTOM_PAD_LINES: u16 = 2;
    pub fn new(params: BottomPaneParams) -> Self {
        let enhanced_keys_supported = params.enhanced_keys_supported;
        Self {
@@ -68,14 +84,40 @@ impl BottomPane<'_> {
            has_input_focus: params.has_input_focus,
            is_task_running: false,
            ctrl_c_quit_hint: false,
+            live_status: None,
+            live_ring: None,
+            status_view_active: false,
        }
    }

    pub fn desired_height(&self, width: u16) -> u16 {
-        self.active_view
+        let overlay_status_h = self
+            .live_status
            .as_ref()
-            .map(|v| v.desired_height(width))
-            .unwrap_or(self.composer.desired_height(width))
+            .map(|s| s.desired_height(width))
+            .unwrap_or(0);
+        let ring_h = self
+            .live_ring
+            .as_ref()
+            .map(|r| r.desired_height(width))
+            .unwrap_or(0);
+
+        let view_height = if let Some(view) = self.active_view.as_ref() {
+            // Add a single blank spacer line between live ring and status view when active.
+            let spacer = if self.live_ring.is_some() && self.status_view_active {
+                1
+            } else {
+                0
+            };
+            spacer + view.desired_height(width)
+        } else {
+            self.composer.desired_height(width)
+        };
+
+        overlay_status_h
+            .saturating_add(ring_h)
+            .saturating_add(view_height)
+            .saturating_add(Self::BOTTOM_PAD_LINES)
    }

    pub fn cursor_pos(&self, area: Rect) -> Option<(u16, u16)> {
@@ -96,10 +138,6 @@ impl BottomPane<'_> {
            view.handle_key_event(self, key_event);
            if !view.is_complete() {
                self.active_view = Some(view);
-            } else if self.is_task_running {
-                self.active_view = Some(Box::new(StatusIndicatorView::new(
-                    self.app_event_tx.clone(),
-                )));
            }
            self.request_redraw();
            InputResult::None
@@ -125,10 +163,6 @@ impl BottomPane<'_> {
            CancellationEvent::Handled => {
                if !view.is_complete() {
                    self.active_view = Some(view);
-                } else if self.is_task_running {
-                    self.active_view = Some(Box::new(StatusIndicatorView::new(
-                        self.app_event_tx.clone(),
-                    )));
                }
                self.show_ctrl_c_quit_hint();
            }
@@ -148,19 +182,37 @@ impl BottomPane<'_> {
        }
    }

-    /// Update the status indicator text (only when the `StatusIndicatorView` is
-    /// active).
+    /// Update the status indicator text. Prefer replacing the composer with
+    /// the StatusIndicatorView so the input pane shows a single-line status
+    /// like: `▌ Working waiting for model`.
    pub(crate) fn update_status_text(&mut self, text: String) {
-        if let Some(view) = &mut self.active_view {
-            match view.update_status_text(text) {
-                ConditionalUpdate::NeedsRedraw => {
-                    self.request_redraw();
-                }
-                ConditionalUpdate::NoRedraw => {
-                    // No redraw needed.
-                }
+        let mut handled_by_view = false;
+        if let Some(view) = self.active_view.as_mut() {
+            if matches!(
+                view.update_status_text(text.clone()),
+                bottom_pane_view::ConditionalUpdate::NeedsRedraw
+            ) {
+                handled_by_view = true;
+            }
+        } else {
+            let mut v = StatusIndicatorView::new(self.app_event_tx.clone());
+            v.update_text(text.clone());
+            self.active_view = Some(Box::new(v));
+            self.status_view_active = true;
+            handled_by_view = true;
+        }
+
+        // Fallback: if the current active view did not consume status updates,
+        // present an overlay above the composer.
+        if !handled_by_view {
+            if self.live_status.is_none() {
+                self.live_status = Some(StatusIndicatorWidget::new(self.app_event_tx.clone()));
+            }
+            if let Some(status) = &mut self.live_status {
+                status.update_text(text);
            }
        }
+        self.request_redraw();
    }

    pub(crate) fn show_ctrl_c_quit_hint(&mut self) {
@@ -186,27 +238,23 @@ impl BottomPane<'_> {
    pub fn set_task_running(&mut self, running: bool) {
        self.is_task_running = running;

-        match (running, self.active_view.is_some()) {
-            (true, false) => {
-                // Show status indicator overlay.
+        if running {
+            if self.active_view.is_none() {
                self.active_view = Some(Box::new(StatusIndicatorView::new(
                    self.app_event_tx.clone(),
                )));
-                self.request_redraw();
+                self.status_view_active = true;
            }
-            (false, true) => {
-                if let Some(mut view) = self.active_view.take() {
-                    if view.should_hide_when_task_is_done() {
-                        // Leave self.active_view as None.
-                        self.request_redraw();
-                    } else {
-                        // Preserve the view.
-                        self.active_view = Some(view);
-                    }
+            self.request_redraw();
+        } else {
+            self.live_status = None;
+            // Drop the status view when a task completes, but keep other
+            // modal views (e.g. approval dialogs).
+            if let Some(mut view) = self.active_view.take() {
+                if !view.should_hide_when_task_is_done() {
+                    self.active_view = Some(view);
                }
-            }
-            _ => {
-                // No change.
+                self.status_view_active = false;
            }
        }
    }
@@ -248,6 +296,7 @@ impl BottomPane<'_> {
        // Otherwise create a new approval modal overlay.
        let modal = ApprovalModalView::new(request, self.app_event_tx.clone());
        self.active_view = Some(Box::new(modal));
+        self.status_view_active = false;
        self.request_redraw()
    }

@@ -281,15 +330,80 @@ impl BottomPane<'_> {
        self.composer.on_file_search_result(query, matches);
        self.request_redraw();
    }
+
+    /// Set the rows and cap for the transient live ring overlay.
+    pub(crate) fn set_live_ring_rows(&mut self, max_rows: u16, rows: Vec<Line<'static>>) {
+        let mut w = live_ring_widget::LiveRingWidget::new();
+        w.set_max_rows(max_rows);
+        w.set_rows(rows);
+        self.live_ring = Some(w);
+    }
+
+    pub(crate) fn clear_live_ring(&mut self) {
+        self.live_ring = None;
+    }
+
+    // Removed restart_live_status_with_text – no longer used by the current streaming UI.
 }

 impl WidgetRef for &BottomPane<'_> {
    fn render_ref(&self, area: Rect, buf: &mut Buffer) {
-        // Show BottomPaneView if present.
-        if let Some(ov) = &self.active_view {
-            ov.render(area, buf);
-        } else {
-            (&self.composer).render_ref(area, buf);
+        let mut y_offset = 0u16;
+        if let Some(ring) = &self.live_ring {
+            let live_h = ring.desired_height(area.width).min(area.height);
+            if live_h > 0 {
+                let live_rect = Rect {
+                    x: area.x,
+                    y: area.y,
+                    width: area.width,
+                    height: live_h,
+                };
+                ring.render_ref(live_rect, buf);
+                y_offset = live_h;
+            }
+        }
+        // Spacer between live ring and status view when active
+        if self.live_ring.is_some() && self.status_view_active && y_offset < area.height {
+            // Leave one empty line
+            y_offset = y_offset.saturating_add(1);
+        }
+        if let Some(status) = &self.live_status {
+            let live_h = status.desired_height(area.width).min(area.height);
+            if live_h > 0 {
+                let live_rect = Rect {
+                    x: area.x,
+                    y: area.y,
+                    width: area.width,
+                    height: live_h,
+                };
+                status.render_ref(live_rect, buf);
+                y_offset = live_h;
+            }
+        }
+
+        if let Some(view) = &self.active_view {
+            if y_offset < area.height {
+                // Reserve bottom padding lines; keep at least 1 line for the view.
+                let avail = area.height - y_offset;
+                let pad = BottomPane::BOTTOM_PAD_LINES.min(avail.saturating_sub(1));
+                let view_rect = Rect {
+                    x: area.x,
+                    y: area.y + y_offset,
+                    width: area.width,
+                    height: avail - pad,
+                };
+                view.render(view_rect, buf);
+            }
+        } else if y_offset < area.height {
+            let composer_rect = Rect {
+                x: area.x,
+                y: area.y + y_offset,
+                width: area.width,
+                // Reserve bottom padding
+                height: (area.height - y_offset)
+                    - BottomPane::BOTTOM_PAD_LINES.min((area.height - y_offset).saturating_sub(1)),
+            };
+            (&self.composer).render_ref(composer_rect, buf);
        }
    }
 }
@@ -298,6 +412,9 @@ impl WidgetRef for &BottomPane<'_> {
 mod tests {
    use super::*;
    use crate::app_event::AppEvent;
+    use ratatui::buffer::Buffer;
+    use ratatui::layout::Rect;
+    use ratatui::text::Line;
    use std::path::PathBuf;
    use std::sync::mpsc::channel;

@@ -324,4 +441,200 @@ mod tests {
        assert!(pane.ctrl_c_quit_hint_visible());
        assert_eq!(CancellationEvent::Ignored, pane.on_ctrl_c());
    }
+
+    #[test]
+    fn live_ring_renders_above_composer() {
+        let (tx_raw, _rx) = channel::<AppEvent>();
+        let tx = AppEventSender::new(tx_raw);
+        let mut pane = BottomPane::new(BottomPaneParams {
+            app_event_tx: tx,
+            has_input_focus: true,
+            enhanced_keys_supported: false,
+        });
+
+        // Provide 4 rows with max_rows=3; only the last 3 should be visible.
+        pane.set_live_ring_rows(
+            3,
+            vec![
+                Line::from("one".to_string()),
+                Line::from("two".to_string()),
+                Line::from("three".to_string()),
+                Line::from("four".to_string()),
+            ],
+        );
+
+        let area = Rect::new(0, 0, 10, 5);
+        let mut buf = Buffer::empty(area);
+        (&pane).render_ref(area, &mut buf);
+
+        // Extract the first 3 rows and assert they contain the last three lines.
+        let mut lines: Vec<String> = Vec::new();
+        for y in 0..3 {
+            let mut s = String::new();
+            for x in 0..area.width {
+                s.push(buf[(x, y)].symbol().chars().next().unwrap_or(' '));
+            }
+            lines.push(s.trim_end().to_string());
+        }
+        assert_eq!(lines, vec!["two", "three", "four"]);
+    }
+
+    #[test]
+    fn status_indicator_visible_with_live_ring() {
+        let (tx_raw, _rx) = channel::<AppEvent>();
+        let tx = AppEventSender::new(tx_raw);
+        let mut pane = BottomPane::new(BottomPaneParams {
+            app_event_tx: tx,
+            has_input_focus: true,
+            enhanced_keys_supported: false,
+        });
+
+        // Simulate task running which replaces composer with the status indicator.
+        pane.set_task_running(true);
+        pane.update_status_text("waiting for model".to_string());
+
+        // Provide 2 rows in the live ring (e.g., streaming CoT) and ensure the
+        // status indicator remains visible below them.
+        pane.set_live_ring_rows(
+            2,
+            vec![
+                Line::from("cot1".to_string()),
+                Line::from("cot2".to_string()),
+            ],
+        );
+
+        // Allow some frames so the dot animation is present.
+        std::thread::sleep(std::time::Duration::from_millis(120));
+
+        // Height should include both ring rows, 1 spacer, and the 1-line status.
+        let area = Rect::new(0, 0, 30, 4);
+        let mut buf = Buffer::empty(area);
+        (&pane).render_ref(area, &mut buf);
+
+        // Top two rows are the live ring.
+        let mut r0 = String::new();
+        let mut r1 = String::new();
+        for x in 0..area.width {
+            r0.push(buf[(x, 0)].symbol().chars().next().unwrap_or(' '));
+            r1.push(buf[(x, 1)].symbol().chars().next().unwrap_or(' '));
+        }
+        assert!(r0.contains("cot1"), "expected first live row: {r0:?}");
+        assert!(r1.contains("cot2"), "expected second live row: {r1:?}");
+
+        // Row 2 is the spacer (blank)
+        let mut r2 = String::new();
+        for x in 0..area.width {
+            r2.push(buf[(x, 2)].symbol().chars().next().unwrap_or(' '));
+        }
+        assert!(r2.trim().is_empty(), "expected blank spacer line: {r2:?}");
+
+        // Bottom row is the status line; it should contain the left bar and "Working".
+        let mut r3 = String::new();
+        for x in 0..area.width {
+            r3.push(buf[(x, 3)].symbol().chars().next().unwrap_or(' '));
+        }
+        assert_eq!(buf[(0, 3)].symbol().chars().next().unwrap_or(' '), '▌');
+        assert!(
+            r3.contains("Working"),
+            "expected Working header in status line: {r3:?}"
+        );
+    }
+
+    #[test]
+    fn bottom_padding_present_for_status_view() {
+        let (tx_raw, _rx) = channel::<AppEvent>();
+        let tx = AppEventSender::new(tx_raw);
+        let mut pane = BottomPane::new(BottomPaneParams {
+            app_event_tx: tx,
+            has_input_focus: true,
+            enhanced_keys_supported: false,
+        });
+
+        // Activate spinner (status view replaces composer) with no live ring.
+        pane.set_task_running(true);
+        pane.update_status_text("waiting for model".to_string());
+
+        // Use height == desired_height; expect 1 status row at top and 2 bottom padding rows.
+        let height = pane.desired_height(30);
+        assert!(
+            height >= 3,
+            "expected at least 3 rows with bottom padding; got {height}"
+        );
+        let area = Rect::new(0, 0, 30, height);
+        let mut buf = Buffer::empty(area);
+        (&pane).render_ref(area, &mut buf);
+
+        // Top row contains the status header
+        let mut top = String::new();
+        for x in 0..area.width {
+            top.push(buf[(x, 0)].symbol().chars().next().unwrap_or(' '));
+        }
+        assert_eq!(buf[(0, 0)].symbol().chars().next().unwrap_or(' '), '▌');
+        assert!(
+            top.contains("Working"),
+            "expected Working header on top row: {top:?}"
+        );
+
+        // Bottom two rows are blank padding
+        let mut r_last = String::new();
+        let mut r_last2 = String::new();
+        for x in 0..area.width {
+            r_last.push(buf[(x, height - 1)].symbol().chars().next().unwrap_or(' '));
+            r_last2.push(buf[(x, height - 2)].symbol().chars().next().unwrap_or(' '));
+        }
+        assert!(
+            r_last.trim().is_empty(),
+            "expected last row blank: {r_last:?}"
+        );
+        assert!(
+            r_last2.trim().is_empty(),
+            "expected second-to-last row blank: {r_last2:?}"
+        );
+    }
+
+    #[test]
+    fn bottom_padding_shrinks_when_tiny() {
+        let (tx_raw, _rx) = channel::<AppEvent>();
+        let tx = AppEventSender::new(tx_raw);
+        let mut pane = BottomPane::new(BottomPaneParams {
+            app_event_tx: tx,
+            has_input_focus: true,
+            enhanced_keys_supported: false,
+        });
+
+        pane.set_task_running(true);
+        pane.update_status_text("waiting for model".to_string());
+
+        // Height=2 → pad shrinks to 1; bottom row is blank, top row has spinner.
+        let area2 = Rect::new(0, 0, 20, 2);
+        let mut buf2 = Buffer::empty(area2);
+        (&pane).render_ref(area2, &mut buf2);
+        let mut row0 = String::new();
+        let mut row1 = String::new();
+        for x in 0..area2.width {
+            row0.push(buf2[(x, 0)].symbol().chars().next().unwrap_or(' '));
+            row1.push(buf2[(x, 1)].symbol().chars().next().unwrap_or(' '));
+        }
+        assert!(
+            row0.contains("Working"),
+            "expected Working header on row 0: {row0:?}"
+        );
+        assert!(
+            row1.trim().is_empty(),
+            "expected bottom padding on row 1: {row1:?}"
+        );
+
+        // Height=1 → no padding; single row is the spinner.
+        let area1 = Rect::new(0, 0, 20, 1);
+        let mut buf1 = Buffer::empty(area1);
+        (&pane).render_ref(area1, &mut buf1);
+        let mut only = String::new();
+        for x in 0..area1.width {
+            only.push(buf1[(x, 0)].symbol().chars().next().unwrap_or(' '));
+        }
+        assert!(
+            only.contains("Working"),
+            "expected Working header with no padding: {only:?}"
+        );
+    }
 }
--- a/codex-rs/tui/src/bottom_pane/textarea.rs
+++ b/codex-rs/tui/src/bottom_pane/textarea.rs
@@ -210,7 +210,7 @@ impl TextArea {
                ..
            } => self.insert_str(&c.to_string()),
            KeyEvent {
-                code: KeyCode::Char('j'),
+                code: KeyCode::Char('j' | 'm'),
                modifiers: KeyModifiers::CONTROL,
                ..
            }
@@ -220,11 +220,22 @@ impl TextArea {
            } => self.insert_str("\n"),
            KeyEvent {
                code: KeyCode::Backspace,
+                modifiers: KeyModifiers::ALT,
+                ..
+            } => self.delete_backward_word(),
+            KeyEvent {
+                code: KeyCode::Backspace,
+                modifiers: KeyModifiers::NONE,
                ..
            } => self.delete_backward(1),
            KeyEvent {
                code: KeyCode::Delete,
                ..
+            }
+            | KeyEvent {
+                code: KeyCode::Char('d'),
+                modifiers: KeyModifiers::CONTROL,
+                ..
            } => self.delete_forward(1),

            KeyEvent {
@@ -303,14 +314,14 @@ impl TextArea {
            }
            KeyEvent {
                code: KeyCode::Left,
-                modifiers: KeyModifiers::CONTROL,
+                modifiers: KeyModifiers::CONTROL | KeyModifiers::ALT,
                ..
            } => {
                self.set_cursor(self.beginning_of_previous_word());
            }
            KeyEvent {
                code: KeyCode::Right,
-                modifiers: KeyModifiers::CONTROL,
+                modifiers: KeyModifiers::CONTROL | KeyModifiers::ALT,
                ..
            } => {
                self.set_cursor(self.end_of_next_word());
--- a/codex-rs/tui/src/chatwidget.rs
+++ b/codex-rs/tui/src/chatwidget.rs
@@ -42,8 +42,10 @@ use crate::exec_command::strip_bash_lc_and_escape;
 use crate::history_cell::CommandOutput;
 use crate::history_cell::HistoryCell;
 use crate::history_cell::PatchEventType;
+use crate::live_wrap::RowBuilder;
 use crate::user_approval_widget::ApprovalRequest;
 use codex_file_search::FileMatch;
+use ratatui::style::Stylize;

 struct RunningCommand {
    command: Vec<String>,
@@ -64,6 +66,10 @@ pub(crate) struct ChatWidget<'a> {
    // at once into scrollback so the history contains a single message.
    answer_buffer: String,
    running_commands: HashMap<String, RunningCommand>,
+    live_builder: RowBuilder,
+    current_stream: Option<StreamKind>,
+    stream_header_emitted: bool,
+    live_max_rows: u16,
 }

 struct UserMessage {
@@ -71,6 +77,12 @@ struct UserMessage {
    image_paths: Vec<PathBuf>,
 }

+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum StreamKind {
+    Answer,
+    Reasoning,
+}
+
 impl From<String> for UserMessage {
    fn from(text: String) -> Self {
        Self {
@@ -151,6 +163,10 @@ impl ChatWidget<'_> {
            reasoning_buffer: String::new(),
            answer_buffer: String::new(),
            running_commands: HashMap::new(),
+            live_builder: RowBuilder::new(80),
+            current_stream: None,
+            stream_header_emitted: false,
+            live_max_rows: 3,
        }
    }

@@ -234,58 +250,45 @@ impl ChatWidget<'_> {

                self.request_redraw();
            }
-            EventMsg::AgentMessage(AgentMessageEvent { message }) => {
-                // Final assistant answer. Prefer the fully provided message
-                // from the event; if it is empty fall back to any accumulated
-                // delta buffer (some providers may only stream deltas and send
-                // an empty final message).
-                let full = if message.is_empty() {
-                    std::mem::take(&mut self.answer_buffer)
-                } else {
-                    self.answer_buffer.clear();
-                    message
-                };
-                if !full.is_empty() {
-                    self.add_to_history(HistoryCell::new_agent_message(&self.config, full));
-                }
+            EventMsg::AgentMessage(AgentMessageEvent { message: _ }) => {
+                // Final assistant answer: commit all remaining rows and close with
+                // a blank line. Use the final text if provided, otherwise rely on
+                // streamed deltas already in the builder.
+                self.finalize_stream(StreamKind::Answer);
                self.request_redraw();
            }
            EventMsg::AgentMessageDelta(AgentMessageDeltaEvent { delta }) => {
-                // Buffer only – do not emit partial lines. This avoids cases
-                // where long responses appear truncated if the terminal
-                // wrapped early. The full message is emitted on
-                // AgentMessage.
+                self.begin_stream(StreamKind::Answer);
                self.answer_buffer.push_str(&delta);
+                self.stream_push_and_maybe_commit(&delta);
+                self.request_redraw();
            }
            EventMsg::AgentReasoningDelta(AgentReasoningDeltaEvent { delta }) => {
-                // Buffer only – disable incremental reasoning streaming so we
-                // avoid truncated intermediate lines. Full text emitted on
-                // AgentReasoning.
+                // Stream CoT into the live pane; keep input visible and commit
+                // overflow rows incrementally to scrollback.
+                self.begin_stream(StreamKind::Reasoning);
                self.reasoning_buffer.push_str(&delta);
+                self.stream_push_and_maybe_commit(&delta);
+                self.request_redraw();
            }
-            EventMsg::AgentReasoning(AgentReasoningEvent { text }) => {
-                // Emit full reasoning text once. Some providers might send
-                // final event with empty text if only deltas were used.
-                let full = if text.is_empty() {
-                    std::mem::take(&mut self.reasoning_buffer)
-                } else {
-                    self.reasoning_buffer.clear();
-                    text
-                };
-                if !full.is_empty() {
-                    self.add_to_history(HistoryCell::new_agent_reasoning(&self.config, full));
-                }
+            EventMsg::AgentReasoning(AgentReasoningEvent { text: _ }) => {
+                // Final reasoning: commit remaining rows and close with a blank.
+                self.finalize_stream(StreamKind::Reasoning);
                self.request_redraw();
            }
            EventMsg::TaskStarted => {
                self.bottom_pane.clear_ctrl_c_quit_hint();
                self.bottom_pane.set_task_running(true);
+                // Replace composer with single-line spinner while waiting.
+                self.bottom_pane
+                    .update_status_text("waiting for model".to_string());
                self.request_redraw();
            }
            EventMsg::TaskComplete(TaskCompleteEvent {
                last_agent_message: _,
            }) => {
                self.bottom_pane.set_task_running(false);
+                self.bottom_pane.clear_live_ring();
                self.request_redraw();
            }
            EventMsg::TokenCount(token_usage) => {
@@ -298,8 +301,8 @@ impl ChatWidget<'_> {
                self.bottom_pane.set_task_running(false);
            }
            EventMsg::PlanUpdate(update) => {
+                // Commit plan updates directly to history (no status-line preview).
                self.add_to_history(HistoryCell::new_plan_update(update));
-                self.request_redraw();
            }
            EventMsg::ExecApprovalRequest(ExecApprovalRequestEvent {
                call_id: _,
@@ -307,8 +310,7 @@ impl ChatWidget<'_> {
                cwd,
                reason,
            }) => {
-                // Print the command to the history so it is visible in the
-                // transcript *before* the modal asks for approval.
+                // Log a background summary immediately so the history is chronological.
                let cmdline = strip_bash_lc_and_escape(&command);
                let text = format!(
                    "command requires approval:\n$ {cmdline}{reason}",
@@ -344,7 +346,6 @@ impl ChatWidget<'_> {
                // approval dialog) and avoids surprising the user with a modal
                // prompt before they have seen *what* is being requested.
                // ------------------------------------------------------------------
-
                self.add_to_history(HistoryCell::new_patch_event(
                    PatchEventType::ApprovalRequest,
                    changes,
@@ -379,8 +380,6 @@ impl ChatWidget<'_> {
                auto_approved,
                changes,
            }) => {
-                // Even when a patch is auto‑approved we still display the
-                // summary so the user can follow along.
                self.add_to_history(HistoryCell::new_patch_event(
                    PatchEventType::ApplyBegin { auto_approved },
                    changes,
@@ -393,6 +392,7 @@ impl ChatWidget<'_> {
                stdout,
                stderr,
            }) => {
+                // Compute summary before moving stdout into the history cell.
                let cmd = self.running_commands.remove(&call_id);
                self.add_to_history(HistoryCell::new_completed_exec_command(
                    cmd.map(|cmd| cmd.command).unwrap_or_else(|| vec![call_id]),
@@ -442,14 +442,15 @@ impl ChatWidget<'_> {
                self.app_event_tx.send(AppEvent::ExitRequest);
            }
            event => {
-                self.add_to_history(HistoryCell::new_background_event(format!("{event:?}")));
+                let text = format!("{event:?}");
+                self.add_to_history(HistoryCell::new_background_event(text.clone()));
+                self.update_latest_log(text);
            }
        }
    }

    /// Update the live log preview while a task is running.
    pub(crate) fn update_latest_log(&mut self, line: String) {
-        // Forward only if we are currently showing the status indicator.
        self.bottom_pane.update_status_text(line);
    }

@@ -515,6 +516,97 @@ impl ChatWidget<'_> {
    }
 }

+impl ChatWidget<'_> {
+    fn begin_stream(&mut self, kind: StreamKind) {
+        if self.current_stream != Some(kind) {
+            self.current_stream = Some(kind);
+            self.stream_header_emitted = false;
+            // Clear any previous live content; we're starting a new stream.
+            self.live_builder = RowBuilder::new(self.live_builder.width());
+            // Ensure the waiting status is visible (composer replaced).
+            self.bottom_pane
+                .update_status_text("waiting for model".to_string());
+        }
+    }
+
+    fn stream_push_and_maybe_commit(&mut self, delta: &str) {
+        self.live_builder.push_fragment(delta);
+
+        // Commit overflow rows (small batches) while keeping the last N rows visible.
+        let drained = self
+            .live_builder
+            .drain_commit_ready(self.live_max_rows as usize);
+        if !drained.is_empty() {
+            let mut lines: Vec<ratatui::text::Line<'static>> = Vec::new();
+            if !self.stream_header_emitted {
+                match self.current_stream {
+                    Some(StreamKind::Reasoning) => {
+                        lines.push(ratatui::text::Line::from("thinking".magenta().italic()));
+                    }
+                    Some(StreamKind::Answer) => {
+                        lines.push(ratatui::text::Line::from("codex".magenta().bold()));
+                    }
+                    None => {}
+                }
+                self.stream_header_emitted = true;
+            }
+            for r in drained {
+                lines.push(ratatui::text::Line::from(r.text));
+            }
+            self.app_event_tx.send(AppEvent::InsertHistory(lines));
+        }
+
+        // Update the live ring overlay lines (text-only, newest at bottom).
+        let rows = self
+            .live_builder
+            .display_rows()
+            .into_iter()
+            .map(|r| ratatui::text::Line::from(r.text))
+            .collect::<Vec<_>>();
+        self.bottom_pane
+            .set_live_ring_rows(self.live_max_rows, rows);
+    }
+
+    fn finalize_stream(&mut self, kind: StreamKind) {
+        if self.current_stream != Some(kind) {
+            // Nothing to do; either already finalized or not the active stream.
+            return;
+        }
+        // Flush any partial line as a full row, then drain all remaining rows.
+        self.live_builder.end_line();
+        let remaining = self.live_builder.drain_rows();
+        // TODO: Re-add markdown rendering for assistant answers and reasoning.
+        // When finalizing, pass the accumulated text through `markdown::append_markdown`
+        // to build styled `Line<'static>` entries instead of raw plain text lines.
+        if !remaining.is_empty() || !self.stream_header_emitted {
+            let mut lines: Vec<ratatui::text::Line<'static>> = Vec::new();
+            if !self.stream_header_emitted {
+                match kind {
+                    StreamKind::Reasoning => {
+                        lines.push(ratatui::text::Line::from("thinking".magenta().italic()));
+                    }
+                    StreamKind::Answer => {
+                        lines.push(ratatui::text::Line::from("codex".magenta().bold()));
+                    }
+                }
+                self.stream_header_emitted = true;
+            }
+            for r in remaining {
+                lines.push(ratatui::text::Line::from(r.text));
+            }
+            // Close the block with a blank line for readability.
+            lines.push(ratatui::text::Line::from(""));
+            self.app_event_tx.send(AppEvent::InsertHistory(lines));
+        }
+
+        // Clear the live overlay and reset state for the next stream.
+        self.live_builder = RowBuilder::new(self.live_builder.width());
+        self.bottom_pane.clear_live_ring();
+        self.current_stream = None;
+        self.stream_header_emitted = false;
+    }
+}
+
 impl WidgetRef for &ChatWidget<'_> {
    fn render_ref(&self, area: Rect, buf: &mut Buffer) {
        // In the hybrid inline viewport mode we only draw the interactive
--- a/codex-rs/tui/src/history_cell.rs
+++ b/codex-rs/tui/src/history_cell.rs
@@ -1,5 +1,4 @@
 use crate::exec_command::strip_bash_lc_and_escape;
-use crate::markdown::append_markdown;
 use crate::text_block::TextBlock;
 use crate::text_formatting::format_and_truncate_tool_result;
 use base64::Engine;
@@ -68,12 +67,7 @@ pub(crate) enum HistoryCell {
    /// Message from the user.
    UserPrompt { view: TextBlock },

-    /// Message from the agent.
-    AgentMessage { view: TextBlock },
-
-    /// Reasoning event from the agent.
-    AgentReasoning { view: TextBlock },
-
+    // AgentMessage and AgentReasoning variants were unused and have been removed.
    /// An exec tool call that has not finished yet.
    ActiveExecCommand { view: TextBlock },

@@ -128,8 +122,6 @@ impl HistoryCell {
        match self {
            HistoryCell::WelcomeMessage { view }
            | HistoryCell::UserPrompt { view }
-            | HistoryCell::AgentMessage { view }
-            | HistoryCell::AgentReasoning { view }
            | HistoryCell::BackgroundEvent { view }
            | HistoryCell::GitDiffOutput { view }
            | HistoryCell::ErrorEvent { view }
@@ -231,28 +223,6 @@ impl HistoryCell {
        }
    }

-    pub(crate) fn new_agent_message(config: &Config, message: String) -> Self {
-        let mut lines: Vec<Line<'static>> = Vec::new();
-        lines.push(Line::from("codex".magenta().bold()));
-        append_markdown(&message, &mut lines, config);
-        lines.push(Line::from(""));
-
-        HistoryCell::AgentMessage {
-            view: TextBlock::new(lines),
-        }
-    }
-
-    pub(crate) fn new_agent_reasoning(config: &Config, text: String) -> Self {
-        let mut lines: Vec<Line<'static>> = Vec::new();
-        lines.push(Line::from("thinking".magenta().italic()));
-        append_markdown(&text, &mut lines, config);
-        lines.push(Line::from(""));
-
-        HistoryCell::AgentReasoning {
-            view: TextBlock::new(lines),
-        }
-    }
-
    pub(crate) fn new_active_exec_command(command: Vec<String>) -> Self {
        let command_escaped = strip_bash_lc_and_escape(&command);

--- a/codex-rs/tui/src/insert_history.rs
+++ b/codex-rs/tui/src/insert_history.rs
@@ -14,7 +14,6 @@ use crossterm::style::SetBackgroundColor;
 use crossterm::style::SetColors;
 use crossterm::style::SetForegroundColor;
 use ratatui::layout::Size;
-use ratatui::prelude::Backend;
 use ratatui::style::Color;
 use ratatui::style::Modifier;
 use ratatui::text::Line;
@@ -22,6 +21,20 @@ use ratatui::text::Span;

 /// Insert `lines` above the viewport.
 pub(crate) fn insert_history_lines(terminal: &mut tui::Tui, lines: Vec<Line>) {
+    let mut out = std::io::stdout();
+    insert_history_lines_to_writer(terminal, &mut out, lines);
+}
+
+/// Like `insert_history_lines`, but writes ANSI to the provided writer. This
+/// is intended for testing where a capture buffer is used instead of stdout.
+pub fn insert_history_lines_to_writer<B, W>(
+    terminal: &mut crate::custom_terminal::Terminal<B>,
+    writer: &mut W,
+    lines: Vec<Line>,
+) where
+    B: ratatui::backend::Backend,
+    W: Write,
+{
    let screen_size = terminal.backend().size().unwrap_or(Size::new(0, 0));
    let cursor_pos = terminal.get_cursor_position().ok();

@@ -32,10 +45,22 @@ pub(crate) fn insert_history_lines(terminal: &mut tui::Tui, lines: Vec<Line>) {
        // If the viewport is not at the bottom of the screen, scroll it down to make room.
        // Don't scroll it past the bottom of the screen.
        let scroll_amount = wrapped_lines.min(screen_size.height - area.bottom());
-        terminal
-            .backend_mut()
-            .scroll_region_down(area.top()..screen_size.height, scroll_amount)
-            .ok();
+
+        // Emit ANSI to scroll the lower region (from the top of the viewport to the bottom
+        // of the screen) downward by `scroll_amount` lines. We do this by:
+        //   1) Limiting the scroll region to [area.top()+1 .. screen_height] (1-based bounds)
+        //   2) Placing the cursor at the top margin of that region
+        //   3) Emitting Reverse Index (RI, ESC M) `scroll_amount` times
+        //   4) Resetting the scroll region back to full screen
+        let top_1based = area.top() + 1; // Convert 0-based row to 1-based for DECSTBM
+        queue!(writer, SetScrollRegion(top_1based..screen_size.height)).ok();
+        queue!(writer, MoveTo(0, area.top())).ok();
+        for _ in 0..scroll_amount {
+            // Reverse Index (RI): ESC M
+            queue!(writer, Print("\x1bM")).ok();
+        }
+        queue!(writer, ResetScrollRegion).ok();
+
        let cursor_top = area.top().saturating_sub(1);
        area.y += scroll_amount;
        terminal.set_viewport_area(area);
@@ -59,23 +84,23 @@ pub(crate) fn insert_history_lines(terminal: &mut tui::Tui, lines: Vec<Line>) {
    // ││                            ││
    // │╰────────────────────────────╯│
    // └──────────────────────────────┘
-    queue!(std::io::stdout(), SetScrollRegion(1..area.top())).ok();
+    queue!(writer, SetScrollRegion(1..area.top())).ok();

    // NB: we are using MoveTo instead of set_cursor_position here to avoid messing with the
    // terminal's last_known_cursor_position, which hopefully will still be accurate after we
    // fetch/restore the cursor position. insert_history_lines should be cursor-position-neutral :)
-    queue!(std::io::stdout(), MoveTo(0, cursor_top)).ok();
+    queue!(writer, MoveTo(0, cursor_top)).ok();

    for line in lines {
-        queue!(std::io::stdout(), Print("\r\n")).ok();
-        write_spans(&mut std::io::stdout(), line.iter()).ok();
+        queue!(writer, Print("\r\n")).ok();
+        write_spans(writer, line.iter()).ok();
    }

-    queue!(std::io::stdout(), ResetScrollRegion).ok();
+    queue!(writer, ResetScrollRegion).ok();

    // Restore the cursor position to where it was before we started.
    if let Some(cursor_pos) = cursor_pos {
-        queue!(std::io::stdout(), MoveTo(cursor_pos.x, cursor_pos.y)).ok();
+        queue!(writer, MoveTo(cursor_pos.x, cursor_pos.y)).ok();
    }
 }

@@ -88,19 +113,25 @@ fn wrapped_line_count(lines: &[Line], width: u16) -> u16 {
 }

 fn line_height(line: &Line, width: u16) -> u16 {
-    use unicode_width::UnicodeWidthStr;
-    // get the total display width of the line, accounting for double-width chars
-    let total_width = line
+    // Use the same visible-width slicing semantics as the live row builder so
+    // our pre-scroll estimation matches how rows will actually wrap.
+    let w = width.max(1) as usize;
+    let mut rows = 0u16;
+    let mut remaining = line
        .spans
        .iter()
-        .map(|span| span.content.width())
-        .sum::<usize>();
-    // divide by width to get the number of lines, rounding up
-    if width == 0 {
-        1
-    } else {
-        (total_width as u16).div_ceil(width).max(1)
+        .map(|s| s.content.as_ref())
+        .collect::<Vec<_>>()
+        .join("");
+    while !remaining.is_empty() {
+        let (_prefix, suffix, taken) = crate::live_wrap::take_prefix_by_width(&remaining, w);
+        rows = rows.saturating_add(1);
+        if taken >= remaining.len() {
+            break;
+        }
+        remaining = suffix.to_string();
    }
+    rows.max(1)
 }

 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -283,4 +314,12 @@ mod tests {
            String::from_utf8(expected).unwrap()
        );
    }
+
+    #[test]
+    fn line_height_counts_double_width_emoji() {
+        let line = Line::from("😀😀😀"); // each emoji ~ width 2
+        assert_eq!(line_height(&line, 4), 2);
+        assert_eq!(line_height(&line, 2), 3);
+        assert_eq!(line_height(&line, 6), 1);
+    }
 }
--- a/codex-rs/tui/src/lib.rs
+++ b/codex-rs/tui/src/lib.rs
@@ -25,13 +25,14 @@ mod bottom_pane;
 mod chatwidget;
 mod citation_regex;
 mod cli;
-mod custom_terminal;
+pub mod custom_terminal;
 mod exec_command;
 mod file_search;
 mod get_git_diff;
 mod git_warning_screen;
 mod history_cell;
-mod insert_history;
+pub mod insert_history;
+pub mod live_wrap;
 mod log_layer;
 mod markdown;
 mod slash_command;
--- a/codex-rs/tui/src/live_wrap.rs
+++ b/codex-rs/tui/src/live_wrap.rs
@@ -0,0 +1,290 @@
+use unicode_width::UnicodeWidthChar;
+use unicode_width::UnicodeWidthStr;
+
+/// A single visual row produced by RowBuilder.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Row {
+    pub text: String,
+    /// True if this row ends with an explicit line break (as opposed to a hard wrap).
+    pub explicit_break: bool,
+}
+
+impl Row {
+    pub fn width(&self) -> usize {
+        self.text.width()
+    }
+}
+
+/// Incrementally wraps input text into visual rows of at most `width` cells.
+///
+/// Step 1: plain-text only. ANSI-carry and styled spans will be added later.
+pub struct RowBuilder {
+    target_width: usize,
+    /// Buffer for the current logical line (until a '\n' is seen).
+    current_line: String,
+    /// Output rows built so far for the current logical line and previous ones.
+    rows: Vec<Row>,
+}
+
+impl RowBuilder {
+    pub fn new(target_width: usize) -> Self {
+        Self {
+            target_width: target_width.max(1),
+            current_line: String::new(),
+            rows: Vec::new(),
+        }
+    }
+
+    pub fn width(&self) -> usize {
+        self.target_width
+    }
+
+    pub fn set_width(&mut self, width: usize) {
+        self.target_width = width.max(1);
+        // Rewrap everything we have (simple approach for Step 1).
+        let mut all = String::new();
+        for row in self.rows.drain(..) {
+            all.push_str(&row.text);
+            if row.explicit_break {
+                all.push('\n');
+            }
+        }
+        all.push_str(&self.current_line);
+        self.current_line.clear();
+        self.push_fragment(&all);
+    }
+
+    /// Push an input fragment. May contain newlines.
+    pub fn push_fragment(&mut self, fragment: &str) {
+        if fragment.is_empty() {
+            return;
+        }
+        let mut start = 0usize;
+        for (i, ch) in fragment.char_indices() {
+            if ch == '\n' {
+                // Flush anything pending before the newline.
+                if start < i {
+                    self.current_line.push_str(&fragment[start..i]);
+                }
+                self.flush_current_line(true);
+                start = i + ch.len_utf8();
+            }
+        }
+        if start < fragment.len() {
+            self.current_line.push_str(&fragment[start..]);
+            self.wrap_current_line();
+        }
+    }
+
+    /// Mark the end of the current logical line (equivalent to pushing a '\n').
+    pub fn end_line(&mut self) {
+        self.flush_current_line(true);
+    }
+
+    /// Drain and return all produced rows.
+    pub fn drain_rows(&mut self) -> Vec<Row> {
+        std::mem::take(&mut self.rows)
+    }
+
+    /// Return a snapshot of produced rows (non-draining).
+    pub fn rows(&self) -> &[Row] {
+        &self.rows
+    }
+
+    /// Rows suitable for display, including the current partial line if any.
+    pub fn display_rows(&self) -> Vec<Row> {
+        let mut out = self.rows.clone();
+        if !self.current_line.is_empty() {
+            out.push(Row {
+                text: self.current_line.clone(),
+                explicit_break: false,
+            });
+        }
+        out
+    }
+
+    /// Drain the oldest rows that exceed `max_keep` display rows (including the
+    /// current partial line, if any). Returns the drained rows in order.
+    pub fn drain_commit_ready(&mut self, max_keep: usize) -> Vec<Row> {
+        let display_count = self.rows.len() + if self.current_line.is_empty() { 0 } else { 1 };
+        if display_count <= max_keep {
+            return Vec::new();
+        }
+        let to_commit = display_count - max_keep;
+        let commit_count = to_commit.min(self.rows.len());
+        let mut drained = Vec::with_capacity(commit_count);
+        for _ in 0..commit_count {
+            drained.push(self.rows.remove(0));
+        }
+        drained
+    }
+
+    fn flush_current_line(&mut self, explicit_break: bool) {
+        // Wrap any remaining content in the current line and then finalize with explicit_break.
+        self.wrap_current_line();
+        // If the current line ended exactly on a width boundary and is non-empty, represent
+        // the explicit break as an empty explicit row so that fragmentation invariance holds.
+        if explicit_break {
+            if self.current_line.is_empty() {
+                // We ended on a boundary previously; add an empty explicit row.
+                self.rows.push(Row {
+                    text: String::new(),
+                    explicit_break: true,
+                });
+            } else {
+                // There is leftover content that did not wrap yet; push it now with the explicit flag.
+                let mut s = String::new();
+                std::mem::swap(&mut s, &mut self.current_line);
+                self.rows.push(Row {
+                    text: s,
+                    explicit_break: true,
+                });
+            }
+        }
+        // Reset current line buffer for next logical line.
+        self.current_line.clear();
+    }
+
+    fn wrap_current_line(&mut self) {
+        // While the current_line exceeds width, cut a prefix.
+        loop {
+            if self.current_line.is_empty() {
+                break;
+            }
+            let (prefix, suffix, taken) =
+                take_prefix_by_width(&self.current_line, self.target_width);
+            if taken == 0 {
+                // Avoid infinite loop on pathological inputs; take one scalar and continue.
+                if let Some((i, ch)) = self.current_line.char_indices().next() {
+                    let len = i + ch.len_utf8();
+                    let p = self.current_line[..len].to_string();
+                    self.rows.push(Row {
+                        text: p,
+                        explicit_break: false,
+                    });
+                    self.current_line = self.current_line[len..].to_string();
+                    continue;
+                }
+                break;
+            }
+            if suffix.is_empty() {
+                // Fits entirely; keep in buffer (do not push yet) so we can append more later.
+                break;
+            } else {
+                // Emit wrapped prefix as a non-explicit row and continue with the remainder.
+                self.rows.push(Row {
+                    text: prefix,
+                    explicit_break: false,
+                });
+                self.current_line = suffix.to_string();
+            }
+        }
+    }
+}
+
+/// Take a prefix of `text` whose visible width is at most `max_cols`.
+/// Returns (prefix, suffix, prefix_width).
+pub fn take_prefix_by_width(text: &str, max_cols: usize) -> (String, &str, usize) {
+    if max_cols == 0 || text.is_empty() {
+        return (String::new(), text, 0);
+    }
+    let mut cols = 0usize;
+    let mut end_idx = 0usize;
+    for (i, ch) in text.char_indices() {
+        let ch_width = UnicodeWidthChar::width(ch).unwrap_or(0);
+        if cols.saturating_add(ch_width) > max_cols {
+            break;
+        }
+        cols += ch_width;
+        end_idx = i + ch.len_utf8();
+        if cols == max_cols {
+            break;
+        }
+    }
+    let prefix = text[..end_idx].to_string();
+    let suffix = &text[end_idx..];
+    (prefix, suffix, cols)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pretty_assertions::assert_eq;
+
+    #[test]
+    fn rows_do_not_exceed_width_ascii() {
+        let mut rb = RowBuilder::new(10);
+        rb.push_fragment("hello whirl this is a test");
+        let rows = rb.rows().to_vec();
+        assert_eq!(
+            rows,
+            vec![
+                Row {
+                    text: "hello whir".to_string(),
+                    explicit_break: false
+                },
+                Row {
+                    text: "l this is ".to_string(),
+                    explicit_break: false
+                }
+            ]
+        );
+    }
+
+    #[test]
+    fn rows_do_not_exceed_width_emoji_cjk() {
+        // 😀 is width 2; 你/好 are width 2.
+        let mut rb = RowBuilder::new(6);
+        rb.push_fragment("😀😀 你好");
+        let rows = rb.rows().to_vec();
+        // At width 6, we expect the first row to fit exactly two emojis and a space
+        // (2 + 2 + 1 = 5) plus one more column for the first CJK char (2 would overflow),
+        // so only the two emojis and the space fit; the rest remains buffered.
+        assert_eq!(
+            rows,
+            vec![Row {
+                text: "😀😀 ".to_string(),
+                explicit_break: false
+            }]
+        );
+    }
+
+    #[test]
+    fn fragmentation_invariance_long_token() {
+        let s = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; // 26 chars
+        let mut rb_all = RowBuilder::new(7);
+        rb_all.push_fragment(s);
+        let all_rows = rb_all.rows().to_vec();
+
+        let mut rb_chunks = RowBuilder::new(7);
+        for i in (0..s.len()).step_by(3) {
+            let end = (i + 3).min(s.len());
+            rb_chunks.push_fragment(&s[i..end]);
+        }
+        let chunk_rows = rb_chunks.rows().to_vec();
+
+        assert_eq!(all_rows, chunk_rows);
+    }
+
+    #[test]
+    fn newline_splits_rows() {
+        let mut rb = RowBuilder::new(10);
+        rb.push_fragment("hello\nworld");
+        let rows = rb.display_rows();
+        assert!(rows.iter().any(|r| r.explicit_break));
+        assert_eq!(rows[0].text, "hello");
+        // Second row should begin with 'world'
+        assert!(rows.iter().any(|r| r.text.starts_with("world")));
+    }
+
+    #[test]
+    fn rewrap_on_width_change() {
+        let mut rb = RowBuilder::new(10);
+        rb.push_fragment("abcdefghijK");
+        assert!(!rb.rows().is_empty());
+        rb.set_width(5);
+        for r in rb.rows() {
+            assert!(r.width() <= 5);
+        }
+    }
+}
--- a/codex-rs/tui/src/markdown.rs
+++ b/codex-rs/tui/src/markdown.rs
@@ -1,3 +1,4 @@
+use crate::citation_regex::CITATION_REGEX;
 use codex_core::config::Config;
 use codex_core::config_types::UriBasedFileOpener;
 use ratatui::text::Line;
@@ -5,8 +6,7 @@ use ratatui::text::Span;
 use std::borrow::Cow;
 use std::path::Path;

-use crate::citation_regex::CITATION_REGEX;
-
+#[allow(dead_code)]
 pub(crate) fn append_markdown(
    markdown_source: &str,
    lines: &mut Vec<Line<'static>>,
@@ -15,6 +15,7 @@ pub(crate) fn append_markdown(
    append_markdown_with_opener_and_cwd(markdown_source, lines, config.file_opener, &config.cwd);
 }

+#[allow(dead_code)]
 fn append_markdown_with_opener_and_cwd(
    markdown_source: &str,
    lines: &mut Vec<Line<'static>>,
@@ -60,6 +61,7 @@ fn append_markdown_with_opener_and_cwd(
 /// ```text
 /// <scheme>://file<ABS_PATH>:<LINE>
 /// ```
+#[allow(dead_code)]
 fn rewrite_file_citations<'a>(
    src: &'a str,
    file_opener: UriBasedFileOpener,
--- a/codex-rs/tui/src/status_indicator_widget.rs
+++ b/codex-rs/tui/src/status_indicator_widget.rs
@@ -9,24 +9,22 @@ use std::thread;
 use std::time::Duration;

 use ratatui::buffer::Buffer;
-use ratatui::layout::Alignment;
 use ratatui::layout::Rect;
 use ratatui::style::Color;
 use ratatui::style::Modifier;
 use ratatui::style::Style;
-use ratatui::style::Stylize;
 use ratatui::text::Line;
 use ratatui::text::Span;
-use ratatui::widgets::Block;
-use ratatui::widgets::BorderType;
-use ratatui::widgets::Borders;
-use ratatui::widgets::Padding;
 use ratatui::widgets::Paragraph;
 use ratatui::widgets::WidgetRef;
+use unicode_width::UnicodeWidthStr;

 use crate::app_event::AppEvent;
 use crate::app_event_sender::AppEventSender;

+// We render the live text using markdown so it visually matches the history
+// cells. Before rendering we strip any ANSI escape sequences to avoid writing
+// raw control bytes into the back buffer.
 use codex_ansi_escape::ansi_escape_line;

 pub(crate) struct StatusIndicatorWidget {
@@ -34,6 +32,14 @@ pub(crate) struct StatusIndicatorWidget {
    /// time).
    text: String,

+    /// Animation state: reveal target `text` progressively like a typewriter.
+    /// We compute the currently visible prefix length based on the current
+    /// frame index and a constant typing speed.  The `base_frame` and
+    /// `reveal_len_at_base` form the anchor from which we advance.
+    last_target_len: usize,
+    base_frame: usize,
+    reveal_len_at_base: usize,
+
    frame_idx: Arc<AtomicUsize>,
    running: Arc<AtomicBool>,
    // Keep one sender alive to prevent the channel from closing while the
@@ -66,9 +72,13 @@ impl StatusIndicatorWidget {
        }

        Self {
-            text: String::from("waiting for logs…"),
+            text: String::from("waiting for model"),
+            last_target_len: 0,
+            base_frame: 0,
+            reveal_len_at_base: 0,
            frame_idx,
            running,
+
            _app_event_tx: app_event_tx,
        }
    }
@@ -79,7 +89,67 @@ impl StatusIndicatorWidget {

    /// Update the line that is displayed in the widget.
    pub(crate) fn update_text(&mut self, text: String) {
-        self.text = text.replace(['\n', '\r'], " ");
+        // If the text hasn't changed, don't reset the baseline; let the
+        // animation continue advancing naturally.
+        if text == self.text {
+            return;
+        }
+        // Update the target text, preserving newlines so wrapping matches history cells.
+        // Strip ANSI escapes for the character count so the typewriter animation speed is stable.
+        let stripped = {
+            let line = ansi_escape_line(&text);
+            line.spans
+                .iter()
+                .map(|s| s.content.as_ref())
+                .collect::<Vec<_>>()
+                .join("")
+        };
+        let new_len = stripped.chars().count();
+
+        // Compute how many characters are currently revealed so we can carry
+        // this forward as the new baseline when target text changes.
+        let current_frame = self.frame_idx.load(std::sync::atomic::Ordering::Relaxed);
+        let shown_now = self.current_shown_len(current_frame);
+
+        self.text = text;
+        self.last_target_len = new_len;
+        self.base_frame = current_frame;
+        self.reveal_len_at_base = shown_now.min(new_len);
+    }
+
+    /// Reset the animation and start revealing `text` from the beginning.
+    #[cfg(test)]
+    pub(crate) fn restart_with_text(&mut self, text: String) {
+        let sanitized = text.replace(['\n', '\r'], " ");
+        let stripped = {
+            let line = ansi_escape_line(&sanitized);
+            line.spans
+                .iter()
+                .map(|s| s.content.as_ref())
+                .collect::<Vec<_>>()
+                .join("")
+        };
+
+        let new_len = stripped.chars().count();
+        let current_frame = self.frame_idx.load(std::sync::atomic::Ordering::Relaxed);
+
+        self.text = sanitized;
+        self.last_target_len = new_len;
+        self.base_frame = current_frame;
+        // Start from zero revealed characters for a fresh typewriter cycle.
+        self.reveal_len_at_base = 0;
+    }
+
+    /// Calculate how many characters should currently be visible given the
+    /// animation baseline and frame counter.
+    fn current_shown_len(&self, current_frame: usize) -> usize {
+        // Increase typewriter speed (~5x): reveal more characters per frame.
+        const TYPING_CHARS_PER_FRAME: usize = 7;
+        let frames = current_frame.saturating_sub(self.base_frame);
+        let advanced = self
+            .reveal_len_at_base
+            .saturating_add(frames.saturating_mul(TYPING_CHARS_PER_FRAME));
+        advanced.min(self.last_target_len)
    }
 }

@@ -92,26 +162,22 @@ impl Drop for StatusIndicatorWidget {

 impl WidgetRef for StatusIndicatorWidget {
    fn render_ref(&self, area: Rect, buf: &mut Buffer) {
-        let widget_style = Style::default();
-        let block = Block::default()
-            .padding(Padding::new(1, 0, 0, 0))
-            .borders(Borders::LEFT)
-            .border_type(BorderType::QuadrantOutside)
-            .border_style(widget_style.dim());
+        // Ensure minimal height
+        if area.height == 0 || area.width == 0 {
+            return;
+        }
+
+        // Build animated gradient header for the word "Working".
        let idx = self.frame_idx.load(std::sync::atomic::Ordering::Relaxed);
        let header_text = "Working";
        let header_chars: Vec<char> = header_text.chars().collect();
-
        let padding = 4usize; // virtual padding around the word for smoother loop
        let period = header_chars.len() + padding * 2;
        let pos = idx % period;
-
        let has_true_color = supports_color::on_cached(supports_color::Stream::Stdout)
            .map(|level| level.has_16m)
            .unwrap_or(false);
-
-        // Width of the bright band (in characters).
-        let band_half_width = 2.0;
+        let band_half_width = 2.0; // width of the bright band in characters

        let mut header_spans: Vec<Span<'static>> = Vec::new();
        for (i, ch) in header_chars.iter().enumerate() {
@@ -133,64 +199,46 @@ impl WidgetRef for StatusIndicatorWidget {
                    .fg(Color::Rgb(level, level, level))
                    .add_modifier(Modifier::BOLD)
            } else {
-                // Bold makes dark gray and gray look the same, so don't use it
-                // when true color is not supported.
+                // Bold makes dark gray and gray look the same, so don't use it when true color is not supported.
                Style::default().fg(color_for_level(level))
            };

            header_spans.push(Span::styled(ch.to_string(), style));
        }

-        header_spans.push(Span::styled(
+        // Plain rendering: no borders or padding so the live cell is visually indistinguishable from terminal scrollback.
+        let inner_width = area.width as usize;
+
+        // Compose a single status line like: "▌ Working [•] waiting for model"
+        let mut spans: Vec<Span<'static>> = Vec::new();
+        spans.push(Span::styled("▌ ", Style::default().fg(Color::Cyan)));
+        // Gradient header
+        spans.extend(header_spans);
+        // Space after header
+        spans.push(Span::styled(
            " ",
            Style::default()
                .fg(Color::White)
                .add_modifier(Modifier::BOLD),
        ));

-        // Ensure we do not overflow width.
-        let inner_width = block.inner(area).width as usize;
-
-        // Sanitize and colour‑strip the potentially colourful log text.  This
-        // ensures that **no** raw ANSI escape sequences leak into the
-        // back‑buffer which would otherwise cause cursor jumps or stray
-        // artefacts when the terminal is resized.
-        let line = ansi_escape_line(&self.text);
-        let mut sanitized_tail: String = line
-            .spans
-            .iter()
-            .map(|s| s.content.as_ref())
-            .collect::<Vec<_>>()
-            .join("");
-
-        // Truncate *after* stripping escape codes so width calculation is
-        // accurate. See UTF‑8 boundary comments above.
-        let header_len: usize = header_spans.iter().map(|s| s.content.len()).sum();
-
-        if header_len + sanitized_tail.len() > inner_width {
-            let available_bytes = inner_width.saturating_sub(header_len);
-
-            if sanitized_tail.is_char_boundary(available_bytes) {
-                sanitized_tail.truncate(available_bytes);
+        // Truncate spans to fit the width.
+        let mut acc: Vec<Span<'static>> = Vec::new();
+        let mut used = 0usize;
+        for s in spans {
+            let w = s.content.width();
+            if used + w <= inner_width {
+                acc.push(s);
+                used += w;
            } else {
-                let mut idx = available_bytes;
-                while idx < sanitized_tail.len() && !sanitized_tail.is_char_boundary(idx) {
-                    idx += 1;
-                }
-                sanitized_tail.truncate(idx);
+                break;
            }
        }
+        let lines = vec![Line::from(acc)];

-        let mut spans = header_spans;
+        // No-op once full text is revealed; the app no longer reacts to a completion event.

-        // Re‑apply the DIM modifier so the tail appears visually subdued
-        // irrespective of the colour information preserved by
-        // `ansi_escape_line`.
-        spans.push(Span::styled(sanitized_tail, Style::default().dim()));
-
-        let paragraph = Paragraph::new(Line::from(spans))
-            .block(block)
-            .alignment(Alignment::Left);
+        let paragraph = Paragraph::new(lines);
        paragraph.render_ref(area, buf);
    }
 }
@@ -204,3 +252,50 @@ fn color_for_level(level: u8) -> Color {
        Color::White
    }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::app_event::AppEvent;
+    use crate::app_event_sender::AppEventSender;
+    use std::sync::mpsc::channel;
+
+    #[test]
+    fn renders_without_left_border_or_padding() {
+        let (tx_raw, _rx) = channel::<AppEvent>();
+        let tx = AppEventSender::new(tx_raw);
+        let mut w = StatusIndicatorWidget::new(tx);
+        w.restart_with_text("Hello".to_string());
+
+        let area = ratatui::layout::Rect::new(0, 0, 30, 1);
+        // Allow a short delay so the typewriter reveals the first character.
+        std::thread::sleep(std::time::Duration::from_millis(120));
+        let mut buf = ratatui::buffer::Buffer::empty(area);
+        w.render_ref(area, &mut buf);
+
+        // Leftmost column has the left bar
+        let ch0 = buf[(0, 0)].symbol().chars().next().unwrap_or(' ');
+        assert_eq!(ch0, '▌', "expected left bar at col 0: {ch0:?}");
+    }
+
+    #[test]
+    fn working_header_is_present_on_last_line() {
+        let (tx_raw, _rx) = channel::<AppEvent>();
+        let tx = AppEventSender::new(tx_raw);
+        let mut w = StatusIndicatorWidget::new(tx);
+        w.restart_with_text("Hi".to_string());
+        // Ensure some frames elapse so we get a stable state.
+        std::thread::sleep(std::time::Duration::from_millis(120));
+
+        let area = ratatui::layout::Rect::new(0, 0, 30, 1);
+        let mut buf = ratatui::buffer::Buffer::empty(area);
+        w.render_ref(area, &mut buf);
+
+        // Single line; it should contain the animated "Working" header.
+        let mut row = String::new();
+        for x in 0..area.width {
+            row.push(buf[(x, 0)].symbol().chars().next().unwrap_or(' '));
+        }
+        assert!(row.contains("Working"), "expected Working header: {row:?}");
+    }
+}
--- a/codex-rs/tui/tests/vt100_history.rs
+++ b/codex-rs/tui/tests/vt100_history.rs
@@ -0,0 +1,214 @@
+#![cfg(feature = "vt100-tests")]
+#![expect(clippy::expect_used)]
+
+use ratatui::backend::TestBackend;
+use ratatui::layout::Rect;
+use ratatui::style::Color;
+use ratatui::style::Style;
+use ratatui::text::Line;
+use ratatui::text::Span;
+
+// Small helper macro to assert a collection contains an item with a clearer
+// failure message.
+macro_rules! assert_contains {
+    ($collection:expr, $item:expr $(,)?) => {
+        assert!(
+            $collection.contains(&$item),
+            "Expected {:?} to contain {:?}",
+            $collection,
+            $item
+        );
+    };
+    ($collection:expr, $item:expr, $($arg:tt)+) => {
+        assert!($collection.contains(&$item), $($arg)+);
+    };
+}
+
+struct TestScenario {
+    width: u16,
+    height: u16,
+    term: codex_tui::custom_terminal::Terminal<TestBackend>,
+}
+
+impl TestScenario {
+    fn new(width: u16, height: u16, viewport: Rect) -> Self {
+        let backend = TestBackend::new(width, height);
+        let mut term = codex_tui::custom_terminal::Terminal::with_options(backend)
+            .expect("failed to construct terminal");
+        term.set_viewport_area(viewport);
+        Self {
+            width,
+            height,
+            term,
+        }
+    }
+
+    fn run_insert(&mut self, lines: Vec<Line<'static>>) -> Vec<u8> {
+        let mut buf: Vec<u8> = Vec::new();
+        codex_tui::insert_history::insert_history_lines_to_writer(&mut self.term, &mut buf, lines);
+        buf
+    }
+
+    fn screen_rows_from_bytes(&self, bytes: &[u8]) -> Vec<String> {
+        let mut parser = vt100::Parser::new(self.height, self.width, 0);
+        parser.process(bytes);
+        let screen = parser.screen();
+
+        let mut rows: Vec<String> = Vec::with_capacity(self.height as usize);
+        for row in 0..self.height {
+            let mut s = String::with_capacity(self.width as usize);
+            for col in 0..self.width {
+                if let Some(cell) = screen.cell(row, col) {
+                    if let Some(ch) = cell.contents().chars().next() {
+                        s.push(ch);
+                    } else {
+                        s.push(' ');
+                    }
+                } else {
+                    s.push(' ');
+                }
+            }
+            rows.push(s.trim_end().to_string());
+        }
+        rows
+    }
+}
+
+#[test]
+fn hist_001_basic_insertion_no_wrap() {
+    // Screen of 20x6; viewport is the last row (height=1 at y=5)
+    let area = Rect::new(0, 5, 20, 1);
+    let mut scenario = TestScenario::new(20, 6, area);
+
+    let lines = vec![Line::from("first"), Line::from("second")];
+    let buf = scenario.run_insert(lines);
+    let rows = scenario.screen_rows_from_bytes(&buf);
+    assert_contains!(rows, String::from("first"));
+    assert_contains!(rows, String::from("second"));
+    let first_idx = rows
+        .iter()
+        .position(|r| r == "first")
+        .expect("expected 'first' row to be present");
+    let second_idx = rows
+        .iter()
+        .position(|r| r == "second")
+        .expect("expected 'second' row to be present");
+    assert_eq!(second_idx, first_idx + 1, "rows should be adjacent");
+}
+
+#[test]
+fn hist_002_long_token_wraps() {
+    let area = Rect::new(0, 5, 20, 1);
+    let mut scenario = TestScenario::new(20, 6, area);
+
+    let long = "A".repeat(45); // > 2 lines at width 20
+    let lines = vec![Line::from(long.clone())];
+    let buf = scenario.run_insert(lines);
+    let mut parser = vt100::Parser::new(6, 20, 0);
+    parser.process(&buf);
+    let screen = parser.screen();
+
+    // Count total A's on the screen
+    let mut count_a = 0usize;
+    for row in 0..6 {
+        for col in 0..20 {
+            if let Some(cell) = screen.cell(row, col) {
+                if let Some(ch) = cell.contents().chars().next() {
+                    if ch == 'A' {
+                        count_a += 1;
+                    }
+                }
+            }
+        }
+    }
+
+    assert_eq!(
+        count_a,
+        long.len(),
+        "wrapped content did not preserve all characters"
+    );
+}
+
+#[test]
+fn hist_003_emoji_and_cjk() {
+    let area = Rect::new(0, 5, 20, 1);
+    let mut scenario = TestScenario::new(20, 6, area);
+
+    let text = String::from("😀😀😀😀😀 你好世界");
+    let lines = vec![Line::from(text.clone())];
+    let buf = scenario.run_insert(lines);
+    let rows = scenario.screen_rows_from_bytes(&buf);
+    let reconstructed: String = rows.join("").chars().filter(|c| *c != ' ').collect();
+    for ch in text.chars().filter(|c| !c.is_whitespace()) {
+        assert!(
+            reconstructed.contains(ch),
+            "missing character {ch:?} in reconstructed screen"
+        );
+    }
+}
+
+#[test]
+fn hist_004_mixed_ansi_spans() {
+    let area = Rect::new(0, 5, 20, 1);
+    let mut scenario = TestScenario::new(20, 6, area);
+
+    let line = Line::from(vec![
+        Span::styled("red", Style::default().fg(Color::Red)),
+        Span::raw("+plain"),
+    ]);
+    let buf = scenario.run_insert(vec![line]);
+    let rows = scenario.screen_rows_from_bytes(&buf);
+    assert_contains!(rows, String::from("red+plain"));
+}
+
+#[test]
+fn hist_006_cursor_restoration() {
+    let area = Rect::new(0, 5, 20, 1);
+    let mut scenario = TestScenario::new(20, 6, area);
+
+    let lines = vec![Line::from("x")];
+    let buf = scenario.run_insert(lines);
+    let s = String::from_utf8_lossy(&buf);
+    // CUP to 1;1 (ANSI: ESC[1;1H)
+    assert!(
+        s.contains("\u{1b}[1;1H"),
+        "expected final CUP to 1;1 in output, got: {s:?}"
+    );
+    // Reset scroll region
+    assert!(
+        s.contains("\u{1b}[r"),
+        "expected reset scroll region in output, got: {s:?}"
+    );
+}
+
+#[test]
+fn hist_005_pre_scroll_region_down() {
+    // Viewport not at bottom: y=3 (0-based), height=1
+    let area = Rect::new(0, 3, 20, 1);
+    let mut scenario = TestScenario::new(20, 6, area);
+
+    let lines = vec![Line::from("first"), Line::from("second")];
+    let buf = scenario.run_insert(lines);
+    let s = String::from_utf8_lossy(&buf);
+    // Expect we limited scroll region to [top+1 .. screen_height] => [4 .. 6] (1-based)
+    assert!(
+        s.contains("\u{1b}[4;6r"),
+        "expected pre-scroll SetScrollRegion 4..6, got: {s:?}"
+    );
+    // Expect we moved cursor to top of that region: row 3 (0-based) => CUP 4;1H
+    assert!(
+        s.contains("\u{1b}[4;1H"),
+        "expected cursor at top of pre-scroll region, got: {s:?}"
+    );
+    // Expect at least two Reverse Index commands (ESC M) for two inserted lines
+    let ri_count = s.matches("\u{1b}M").count();
+    assert!(
+        ri_count >= 1,
+        "expected at least one RI (ESC M), got: {s:?}"
+    );
+    // After pre-scroll, we set insertion scroll region to [1 .. new_top] => [1 .. 5]
+    assert!(
+        s.contains("\u{1b}[1;5r"),
+        "expected insertion SetScrollRegion 1..5, got: {s:?}"
+    );
+}
--- a/codex-rs/tui/tests/vt100_live_commit.rs
+++ b/codex-rs/tui/tests/vt100_live_commit.rs
@@ -0,0 +1,101 @@
+#![cfg(feature = "vt100-tests")]
+
+use ratatui::backend::TestBackend;
+use ratatui::layout::Rect;
+use ratatui::text::Line;
+
+#[test]
+fn live_001_commit_on_overflow() {
+    let backend = TestBackend::new(20, 6);
+    let mut term = match codex_tui::custom_terminal::Terminal::with_options(backend) {
+        Ok(t) => t,
+        Err(e) => panic!("failed to construct terminal: {e}"),
+    };
+    let area = Rect::new(0, 5, 20, 1);
+    term.set_viewport_area(area);
+
+    // Build 5 explicit rows at width 20.
+    let mut rb = codex_tui::live_wrap::RowBuilder::new(20);
+    rb.push_fragment("one\n");
+    rb.push_fragment("two\n");
+    rb.push_fragment("three\n");
+    rb.push_fragment("four\n");
+    rb.push_fragment("five\n");
+
+    // Keep the last 3 in the live ring; commit the first 2.
+    let commit_rows = rb.drain_commit_ready(3);
+    let lines: Vec<Line<'static>> = commit_rows
+        .into_iter()
+        .map(|r| Line::from(r.text))
+        .collect();
+
+    let mut buf: Vec<u8> = Vec::new();
+    codex_tui::insert_history::insert_history_lines_to_writer(&mut term, &mut buf, lines);
+
+    let mut parser = vt100::Parser::new(6, 20, 0);
+    parser.process(&buf);
+    let screen = parser.screen();
+
+    // The words "one" and "two" should appear above the viewport.
+    let mut joined = String::new();
+    for row in 0..6 {
+        for col in 0..20 {
+            if let Some(cell) = screen.cell(row, col) {
+                if let Some(ch) = cell.contents().chars().next() {
+                    joined.push(ch);
+                } else {
+                    joined.push(' ');
+                }
+            }
+        }
+        joined.push('\n');
+    }
+    assert!(
+        joined.contains("one"),
+        "expected committed 'one' to be visible\n{joined}"
+    );
+    assert!(
+        joined.contains("two"),
+        "expected committed 'two' to be visible\n{joined}"
+    );
+    // The last three (three,four,five) remain in the live ring, not committed here.
+}
+
+#[test]
+fn live_002_pre_scroll_and_commit() {
+    let backend = TestBackend::new(20, 6);
+    let mut term = match codex_tui::custom_terminal::Terminal::with_options(backend) {
+        Ok(t) => t,
+        Err(e) => panic!("failed to construct terminal: {e}"),
+    };
+    // Viewport not at bottom: y=3
+    let area = Rect::new(0, 3, 20, 1);
+    term.set_viewport_area(area);
+
+    let mut rb = codex_tui::live_wrap::RowBuilder::new(20);
+    rb.push_fragment("alpha\n");
+    rb.push_fragment("beta\n");
+    rb.push_fragment("gamma\n");
+    rb.push_fragment("delta\n");
+
+    // Keep 3, commit 1.
+    let commit_rows = rb.drain_commit_ready(3);
+    let lines: Vec<Line<'static>> = commit_rows
+        .into_iter()
+        .map(|r| Line::from(r.text))
+        .collect();
+
+    let mut buf: Vec<u8> = Vec::new();
+    codex_tui::insert_history::insert_history_lines_to_writer(&mut term, &mut buf, lines);
+    let s = String::from_utf8_lossy(&buf);
+
+    // Expect a SetScrollRegion to [area.top()+1 .. screen_height] and a cursor move to top of that region.
+    assert!(
+        s.contains("\u{1b}[4;6r"),
+        "expected pre-scroll region 4..6, got: {s:?}"
+    );
+    assert!(
+        s.contains("\u{1b}[4;1H"),
+        "expected cursor CUP 4;1H, got: {s:?}"
+    );
+}