## Why
The TUI currently treats Markdown tables as ordinary wrapped text, which
makes table-heavy responses hard to read and brittle across narrow panes
and terminal resizes.
This change teaches the TUI to render Markdown tables responsively while
preserving the raw Markdown source needed to re-render streamed and
finalized transcript content after width changes. The goal is to keep
tables legible during streaming, after resize, and once a turn has
finished, without corrupting scrollback ordering.
## What Changed
- add table detection and responsive table rendering in the Markdown
renderer
- render standard tables with Unicode box-drawing borders when the pane
is wide enough
- add a vertical readability fallback for constrained or dense tables so
narrow panes still show each row clearly
- keep links and `<br>` content inside table cells instead of leaking
text outside the table
- avoid table normalization inside fenced or indented code blocks
- preserve raw streamed Markdown source and keep the active table as a
mutable tail until finalization
- consolidate finalized streamed content into source-backed transcript
cells so post-resize re-rendering stays correct
- add snapshot and targeted streaming/resize regression coverage for the
new table behavior
## How to Test
1. Start Codex TUI from this branch.
2. Paste this exact prompt:
`This is a session to test codex, no need to do any thinking, just end
different markdown tables, with columns exploring different markdown
contents, like links, bold italic, code, etc. Make them different sizes,
some 30+ rows, some not and intertwine them with some paragraphs with
complex formatting as well.`
3. Confirm the response includes several Markdown tables mixed with
richly formatted paragraphs.
4. Confirm wide-enough tables render with box-drawing borders instead of
plain wrapped pipe text.
5. Resize the terminal narrower while the answer is still streaming and
confirm the in-progress table stays coherent instead of duplicating
headers or leaving broken scrollback behind.
6. Resize again after the turn finishes and confirm the finalized
transcript re-renders cleanly at the new width.
7. In a narrow pane, verify dense tables fall back to the vertical
per-row layout instead of producing unreadable wrapped columns.
8. Also verify pipe-heavy fenced code blocks still render as code, not
as tables.
Targeted tests:
- `cargo test -p codex-tui table_readability_fallback --no-fail-fast`
- `cargo test -p codex-tui markdown_render --no-fail-fast`
- `cargo test -p codex-tui streaming::controller --no-fail-fast`
- `cargo test -p codex-tui table_resize_lifecycle --no-fail-fast`
## Docs
No developer docs update appears necessary.
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.
We don't instruct the model to use citations, so it never emits them.
Further, ratatui [doesn't currently support rendering links into the
terminal with OSC 8](https://github.com/ratatui/ratatui/issues/1028), so
even if we did parse citations, we can't correctly render them.
So, remove all the code related to rendering them.
Also, simplify the streaming behavior.
This fixes a number of display issues with streaming markdown, and paves
the way for better markdown features (e.g. customizable styles, syntax
highlighting, markdown-aware wrapping).
Not currently supported:
- footnotes
- tables
- reference-style links
This was mostly written by codex under heavy guidance via test cases
drawn from logged session data and fuzzing. It also uncovered some bugs
in tui_markdown, which will in some cases split a list marker from the
list item content. We're not addressing those bugs for now.
Wait for newlines, then render markdown on a line by line basis. Word wrap it for the current terminal size and then spit it out line by line into the UI. Also adds tests and fixes some UI regressions.
We wait until we have an entire newline, then format it with markdown and stream in to the UI. This reduces time to first token but is the right thing to do with our current rendering model IMO. Also lets us add word wrapping!
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.
`config.rs` is already quite long without these definitions. Since they
have no real dependencies of their own, let's move them to their own
file so `config.rs` can focus on the business logic of loading a config.
This introduces the use of the `tui-markdown` crate to parse an
assistant message as Markdown and style it using ANSI for a better user
experience. As shown in the screenshot below, it has support for syntax
highlighting for _tagged_ fenced code blocks:
<img width="907" alt="image"
src="https://github.com/user-attachments/assets/900dc229-80bb-46e8-b1bb-efee4c70ba3c"
/>
That said, `tui-markdown` is not as configurable (or stylish!) as
https://www.npmjs.com/package/marked-terminal, which is what we use in
the TypeScript CLI. In particular:
* The styles are hardcoded and `tui_markdown::from_str()` does not take
any options whatsoever. It uses "bold white" for inline code style which
does not stand out as much as the yellow used by `marked-terminal`:
65402cbda7/tui-markdown/src/lib.rs (L464)
I asked Codex to take a first pass at this and it came up with:
https://github.com/joshka/tui-markdown/pull/80
* If a fenced code block is not tagged, then it does not get
highlighted. I would rather add some logic here:
65402cbda7/tui-markdown/src/lib.rs (L262)
that uses something like https://pypi.org/project/guesslang/ to examine
the value of `text` and try to use the appropriate syntax highlighter.
* When we have a fenced code block, we do not want to show the opening
and closing triple backticks in the output.
To unblock ourselves, we might want to bundle our own fork of
`tui-markdown` temporarily until we figure out what the shape of the API
should be and then try to upstream it.
