## 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
## What?
Fixed error handling in `insert_history_lines_to_writer` where all
terminal operations were silently ignoring errors via `.ok()`.
## Why?
Silent I/O failures could leave the terminal in an inconsistent state
(e.g., scroll region not reset) with no way to debug. This violates Rust
error handling best practices.
## How?
- Changed function signature to return `io::Result<()>`
- Replaced all `.ok()` calls with `?` operator to propagate errors
- Added `tracing::warn!` in wrapper function for backward compatibility
- Updated 15 test call sites to handle Result with `.expect()`
## Testing
- ✅ Pass all tests
## Type of Change
- [x] Bug fix (non-breaking change)
---------
Signed-off-by: Huaiwu Li <lhwzds@gmail.com>
Co-authored-by: Eric Traut <etraut@openai.com>
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
i'm not yet convinced i have the best heuristics for what to highlight,
but this feels like a useful step towards something a bit easier to
read, esp. when the model is producing large commands.
<img width="669" height="589" alt="Screenshot 2025-09-03 at 8 21 56 PM"
src="https://github.com/user-attachments/assets/b9cbcc43-80e8-4d41-93c8-daa74b84b331"
/>
also a fairly significant refactor of our line wrapping logic.
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
This PR:
* Added the clippy.toml to configure allowable expect / unwrap usage in
tests
* Removed as many expect/allow lines as possible from tests
* moved a bunch of allows to expects where possible
Note: in integration tests, non `#[test]` helper functions are not
covered by this so we had to leave a few lingering `expect(expect_used`
checks around
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.
This fixes a bug in insert_history_lines where writing
`Line::From(vec!["A".bold(), "B".into()])` would write "B" as bold,
because "B" didn't explicitly subtract bold.
this fixes a couple of panics that would happen when trying to render
something larger than the terminal, or insert history lines when the top
of the viewport is at y=0.
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™
The overall idea here is: skip ratatui for writing into scrollback,
because its primitives are wrong. We want to render full lines of text,
that will be wrapped natively by the terminal, and which we never plan
to update using ratatui (so the `Buffer` struct is overhead and in fact
an inhibition).
Instead, we use ANSI scrolling regions (link reference doc to come).
Essentially, we:
1. Define a scrolling region that extends from the top of the prompt
area all the way to the top of scrollback
2. Scroll that region up by N < (screen_height - viewport_height) lines,
in this PR N=1
3. Put our cursor at the top of the newly empty region
4. Print out our new text like normal
The terminal interactions here (write_spans and its dependencies) are
mostly extracted from ratatui.
This update replaces the previous ratatui history widget with an
append-only log so that the terminal can handle text selection and
scrolling. It also disables streaming responses, which we'll do our best
to bring back in a later PR. It also adds a small summary of token use
after the TUI exits.
