A beta tester photographed claude's `❯` prompt and its `⏵⏵` bypass-permissions
marker rendering as empty boxes in the preview pane. Their font has no coverage
for those codepoints while drawing `·`, `─`, `│` and `▶` perfectly.
The glyph TIER cannot help here. It answers "can this terminal do Unicode at
all", which is a locale question, and it correctly says yes for exactly the
terminals this affects. Coverage is per-glyph and undetectable from inside the
process, so the handful of rare glyphs CLIs use as chrome are folded to the
ASCII arrows they already look like, and everything a plain font does render is
left alone.
Scoped tightly: the preview only, never the TUI's own chrome, and skipped
entirely at the `nerd` tier where the user has declared a font that can draw
anything. The table is short and every entry was seen as tofu in a real
terminal rather than guessed at. The fold is length-preserving, so the preview
pane's column arithmetic is unaffected.
Measured against a live Claude pane: an Ink TUI paints by ROW and emits
almost no newlines, so dropping cursor-position sequences collapsed a whole
screen into one unreadable line, and a tail cut mid-sequence printed the
remains of it (";1H") as text. Now a jump to column 1 starts a display line,
a jump inside a row moves the write position (capped, since a stream may
address a column no terminal has), and a severed CSI head is dropped before
parsing.
The preview is readable against a real session as a result: tool calls, the
working line and the composer all land where they belong.
Also drop the repeated session name from a search row, whose snippet opens
with the name the row already shows in its first column.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The preview pane shows a session's raw terminal stream, so it needs the tail
reconstructed rather than emulated: SGR survives, cursor steering and OSC do
not, and a carriage return returns to column 0 so a spinner that repaints its
line 200 times contributes one line instead of 200.
Widths count East Asian Wide characters as two columns, which the clip and pad
helpers rely on to never cut a wide character, a code point or an escape
sequence in half.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Codeman maintainer