## TL;DR
Fixes the issues when using Codex CLI with Zellij multiplexer. Before
this PR there would be no scrollback when using it inside a zellij
terminal.
## Problem
Addresses #2558
Zellij does not support ANSI scroll-region manipulation (`DECSTBM` /
Reverse Index) or the alternate screen buffer in the way traditional
terminals do. When codex's TUI runs inside Zellij, two things break: (1)
inline history insertion corrupts the display because the scroll-region
escape sequences are silently dropped or mishandled, and (2) the
composer textarea renders with inherited background/foreground styles
that produce unreadable text against Zellij's pane chrome.
## Mental model
The fix introduces a **Zellij mode** — a runtime boolean detected once
at startup via `codex_terminal_detection::terminal_info().is_zellij()` —
that gates two subsystems onto Zellij-safe terminal strategies:
- **History insertion** (`insert_history.rs`): Instead of using
`DECSTBM` scroll regions and Reverse Index (`ESC M`) to slide content
above the viewport, Zellij mode scrolls the screen by emitting `\n` at
the bottom row and then writes history lines at absolute positions. This
avoids every escape sequence Zellij mishandles.
- **Viewport expansion** (`tui.rs`): When the viewport grows taller than
available space, the standard path uses `scroll_region_up` on the
backend. Zellij mode instead emits newlines at the screen bottom to push
content up, then invalidates the ratatui diff buffer so the next draw is
a full repaint.
- **Composer rendering** (`chat_composer.rs`, `textarea.rs`): All text
rendering in the input area uses an explicit `base_style` with
`Color::Reset` foreground, preventing Zellij's pane styling from
bleeding into the textarea. The prompt chevron (`›`) and placeholder
text use explicit color constants instead of relying on `.bold()` /
`.dim()` modifiers that render inconsistently under Zellij.
## Non-goals
- This change does not fix or improve Zellij's terminal emulation
itself.
- It does not rearchitect the inline viewport model; it adds a parallel
code path gated on detection.
- It does not touch the alternate-screen disable logic (that already
existed and continues to use `is_zellij` via the same detection).
## Tradeoffs
- **Code duplication in `insert_history.rs`**: The Zellij and Standard
branches share the line-rendering loop (color setup, span merging,
`write_spans`) but differ in the scrolling preamble. The duplication is
intentional — merging them would force a complex conditional state
machine that's harder to reason about than two flat sequences.
- **`invalidate_viewport` after every Zellij history flush or viewport
expansion**: This forces a full repaint on every draw cycle in Zellij,
which is more expensive than ratatui's normal diff-based rendering. This
is necessary because Zellij's lack of scroll-region support means the
diff buffer's assumptions about what's on screen are invalid after we
manually move content.
- **Explicit colors vs semantic modifiers**: Replacing `.bold()` /
`.dim()` with `Color::Cyan` / `Color::DarkGray` / `Color::White` in the
Zellij branch sacrifices theme-awareness for correctness. If the project
ever adopts a theming system, Zellij styling will need to participate.
## Architecture
The Zellij detection flag flows through three layers:
1. **`codex_terminal_detection`** — `TerminalInfo::is_zellij()` (new
convenience method) reads the already-detected `Multiplexer` variant.
2. **`Tui` struct** — caches `is_zellij` at construction; passes it into
`update_inline_viewport`, `flush_pending_history_lines`, and
`insert_history_lines_with_mode`.
3. **`ChatComposer` struct** — independently caches `is_zellij` at
construction; uses it in `render_textarea` for style decisions.
The two caches (`Tui.is_zellij` and `ChatComposer.is_zellij`) are read
from the same global `OnceLock<TerminalInfo>`, so they always agree.
## Observability
No new logging, metrics, or tracing is introduced. Diagnosis depends on:
- Whether `ZELLIJ` or `ZELLIJ_SESSION_NAME` env vars are set (the
detection heuristic).
- Visual inspection of the rendered TUI inside Zellij vs a standard
terminal.
- The insta snapshot `zellij_empty_composer` captures the Zellij-mode
render path.
## Tests
- `terminal_info_reports_is_zellij` — unit test in `terminal-detection`
confirming the convenience method.
- `zellij_empty_composer_snapshot` — insta snapshot in `chat_composer`
validating the Zellij render path for an empty composer.
- `vt100_zellij_mode_inserts_history_and_updates_viewport` — integration
test in `insert_history` verifying that Zellij-mode history insertion
writes content and shifts the viewport.
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This is a follow-up to https://github.com/openai/codex/pull/15922. That
previous PR deleted the old `tui` directory and left the new
`tui_app_server` directory in place. This PR renames `tui_app_server` to
`tui` and fixes up all references.
This is the part 1 of 2 PRs that will delete the `tui` /
`tui_app_server` split. This part simply deletes the existing `tui`
directory and marks the `tui_app_server` feature flag as removed. I left
the `tui_app_server` feature flag in place for now so its presence
doesn't result in an error. It is simply ignored.
Part 2 will rename the `tui_app_server` directory `tui`. I did this as
two parts to reduce visible code churn.
## Problem
Long URLs containing `/` and `-` characters are split across multiple
terminal lines by `textwrap`'s default hyphenation rules. This breaks
terminal link detection: emulators can no longer identify the URL as
clickable, and copy-paste yields a truncated fragment. The issue affects
every view that renders user or agent text — exec output, history cells,
markdown, the app-link setup screen, and the VT100 scrollback path.
A secondary bug compounds the first: `desired_height()` calculations
count logical lines rather than viewport rows. When a URL overflows its
line and wraps visually, the height budget is too small, causing content
to clip or leave gaps.
Here is how the complete URL is interpreted by the terminal before
(first line only) and after (complete URL):
| Before | After |
|---|---|
| <img width="777" height="1002" alt="Screenshot 2026-02-17 at 7 59 11
PM"
src="https://github.com/user-attachments/assets/193a89a0-7e56-49c5-8b76-53499a76e7e3"
/> | <img width="777" height="1002" alt="Screenshot 2026-02-17 at 7 58
40 PM"
src="https://github.com/user-attachments/assets/0b9b4c14-aafb-439f-9ffe-f6bba556f95e"
/> |
## Mental model
The TUI now treats URL-like tokens as atomic units that must never be
split by the wrapping engine. Every call site that previously used
`word_wrap_*` has been migrated to `adaptive_wrap_*`, which inspects
each line for URL-like tokens and switches wrapping strategy
accordingly:
- **Non-URL lines** follow the existing `textwrap` path unchanged (word
boundaries, optional indentation, hyphenation).
- **URL-only lines** (with at most decorative markers like `│`, `-`,
`1.`) are emitted unwrapped so terminal link detection works; ratatui's
`Wrap { trim: false }` handles the final character wrap at render time.
- **Mixed lines** (URL + substantive non-URL prose) flow through
`adaptive_wrap_line` so prose wraps naturally at word boundaries while
URL tokens remain unsplit.
Height measurement everywhere now delegates to
`Paragraph::line_count(width)`, which accounts for the visual row cost
of overflowed lines. This single source of truth replaces ad-hoc line
counting in individual cells.
For terminal scrollback (the VT100 path that prints history when the TUI
exits), URL-only lines are emitted unwrapped so the terminal's own link
detector can find them. Mixed URL+prose lines use adaptive wrapping so
surrounding text wraps naturally. Continuation rows are pre-cleared to
avoid stale content artifacts.
## Non-goals
- Full RFC 3986 URL parsing. The detector is a conservative heuristic
that covers `scheme://host`, bare domains (`example.com/path`),
`localhost:port`, and IPv4 hosts. IPv6 (`[::1]:8080`) and exotic schemes
are intentionally excluded from v1.
- Changing wrapping behavior for non-URL content.
- Reflowing or reformatting existing terminal scrollback on resize.
## Tradeoffs
| Decision | Upside | Downside |
|----------|--------|----------|
| Heuristic URL detection vs. full parser | Fast, zero-alloc on the hot
path; conservative enough to reject file paths like `src/main.rs` |
False negatives on obscure URL formats (they get split as before) |
| Adaptive (three-path) wrapping | Non-URL lines are untouched — no
behavior change, no perf cost; mixed lines wrap prose naturally while
preserving URLs | Three wrapping strategies to reason about when
debugging layout |
| Row-based truncation with line-unit ellipsis | Accurate viewport
budget; stable "N lines omitted" count across terminal widths |
`truncate_lines_middle` is more complex (must compute per-line row cost)
|
| Unwrapped URL-only lines in scrollback | Terminal emulators detect
clickable links; copy-paste gets the full URL | TUI and scrollback
formatting diverge for URL-only lines |
| Default `desired_height` via `Paragraph::line_count` | DRY — most
cells inherit correct measurement | Cells with custom layout must
remember to override |
## Architecture
```mermaid
flowchart TD
A["adaptive_wrap_*()"] --> B{"line_contains_url_like?"}
B -- No URL tokens --> C["word_wrap_line<br/>(textwrap default)"]
B -- Has URL tokens --> D{"mixed URL + prose?"}
D -- "URL-only<br/>(+ decorative markers)" --> E["emit unwrapped<br/>(terminal char-wraps)"]
D -- "Mixed<br/>(URL + substantive text)" --> F["adaptive_wrap_line<br/>(AsciiSpace + custom WordSplitter)"]
C --> G["Paragraph::line_count(w)<br/>(single height truth)"]
E --> G
F --> G
```
**Changed files:**
| File | Role |
|------|------|
| `wrapping.rs` | URL detection heuristics, mixed-line detection,
`adaptive_wrap_*` functions, custom `WordSplitter` |
| `exec_cell/render.rs` | Row-aware `truncate_lines_middle`, adaptive
wrapping for command/output display |
| `history_cell.rs` | Migrate all cell types to `adaptive_wrap_*`;
default `desired_height` via `Paragraph::line_count` |
| `insert_history.rs` | Three-path scrollback wrapping (unwrapped
URL-only, adaptive mixed, word-wrapped text); continuation row clearing
|
| `app_link_view.rs` | Adaptive wrapping for setup URL; `desired_height`
via `Paragraph::line_count` |
| `markdown_render.rs` | Adaptive wrapping in `finish_paragraph` |
| `model_migration.rs` | Viewport-aware wrapping for narrow-pane
markdown |
| `pager_overlay.rs` | `Wrap { trim: false }` for transcript and
streaming chunks |
| `queued_user_messages.rs` | Migrate to `adaptive_wrap_lines` |
| `status/card.rs` | Migrate to `adaptive_wrap_lines` |
## Observability
- **Ellipsis message** in truncated exec output reports omitted count in
logical lines (stable across resize) rather than viewport rows
(fluctuates).
- URL detection is deterministic and stateless — no hidden caching or
memoization to go stale.
- Height mismatch bugs surface immediately as visual clipping or gaps;
the `Paragraph::line_count` path is the same code ratatui uses at render
time, so measurement and rendering cannot diverge.
## Tests
26 new unit tests across 7 files, covering:
- **URL integrity**: assert a URL-like token appears on exactly one
rendered line (not split across two).
- **Height accuracy**: compare `desired_height()` against
`Paragraph::line_count()` for URL-containing content.
- **Row-aware truncation**: verify ellipsis counts logical lines and
output fits within the row budget.
- **Scrollback rendering**: VT100 backend tests confirm prefix and URL
land on the same row; continuation rows are cleared; mixed URL+prose
lines wrap prose while preserving URL tokens.
- **Mixed URL+prose detection**: `line_has_mixed_url_and_non_url_tokens`
correctly distinguishes lines with substantive non-URL text from lines
with only decorative markers alongside a URL.
- **Heuristic correctness**: positive matches (`https://...`,
`example.com/path`, `localhost:3000/api`, `192.168.1.1:8080/health`) and
negative matches (`src/main.rs`, `foo/bar`, `hello-world`).
## Risks and open items
1. **URL-like tokens in code output** (e.g. `example.com/api` inside a
JSON blob) will trigger URL-preserving wrap on that line. This is
acceptable — the worst case is a slightly wider line, not broken output.
2. **Very long non-URL tokens on a URL line** can only break at
character boundaries (the custom splitter emits all char indices for
non-URL words). On extremely narrow terminals this could overflow, but
narrow terminals already degrade gracefully.
3. **No IPv6 support** — `[::1]:8080/path` will be treated as a non-URL
and may get split. Can be added later without API changes.
Fixes#5457
Removes flush logic that was leftover to test against ratatui's flush
Cleaned up the flush logic so it's a bit more intent revealing.
DrawCommand now owns the Cells that it draws as this works around a
borrow checker problem.
Fixes#4870#4717#3260#4431#2718#4898#5036
- Fix the chat composer “phantom space” bug that appeared when
backspacing CJK (and other double-width) characters after the composer
got a uniform background in 43b63ccae89c….
- Pull diff_buffers’s clear-to-end logic forward to iterate by display
width, so wide graphemes are counted correctly when computing the
trailing column.
- Keep modifier-aware detection so styled cells are still flushed, and
add a regression test (diff_buffers_clear_to_end_starts_after_wide_char)
that covers the CJK deletion scenario.
---------
Co-authored-by: Josh McKinney <joshka@openai.com>
before:
```
$ time cargo test -p codex-tui -q
[...]
cargo test -p codex-tui -q 39.89s user 10.77s system 98% cpu 51.328 total
```
after:
```
$ time cargo test -p codex-tui -q
[...]
cargo test -p codex-tui -q 1.37s user 0.64s system 29% cpu 6.699 total
```
the major offenders were the textarea fuzz test and the custom_terminal
doctests. (i think the doctests were being recompiled every time which
made them extra slow?)
this is in preparation for adding more separate "modes" to the tui, in
particular, a "transcript mode" to view a full history once #2316 lands.
1. split apart "tui events" from "app events".
2. remove onboarding-related events from AppEvent.
3. move several general drawing tools out of App and into a new Tui
class
Codex created this PR from the following prompt:
> upgrade this entire repo to Rust 1.89. Note that this requires
updating codex-rs/rust-toolchain.toml as well as the workflows in
.github/. Make sure that things are "clippy clean" as this change will
likely uncover new Clippy errors. `just fmt` and `cargo clippy --tests`
are sufficient to check for correctness
Note this modifies a lot of lines because it folds nested `if`
statements using `&&`.
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/2465).
* #2467
* __->__ #2465
Proof of concept for a resizable viewport.
The general approach here is to duplicate the `Terminal` struct from
ratatui, but with our own logic. This is a "light fork" in that we are
still using all the base ratatui functions (`Buffer`, `Widget` and so
on), but we're doing our own bookkeeping at the top level to determine
where to draw everything.
This approach could use improvement—e.g, when the window is resized to a
smaller size, if the UI wraps, we don't correctly clear out the
artifacts from wrapping. This is possible with a little work (i.e.
tracking what parts of our UI would have been wrapped), but this
behavior is at least at par with the existing behavior.
https://github.com/user-attachments/assets/4eb17689-09fd-4daa-8315-c7ebc654986d
cc @joshka who might have Thoughts™
