fix(vterm): track SGR per cell so re-attach replays colors#24
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The emulator stored bare runes and discarded SGR by design, so the
replay a re-attaching client receives (Redraw) repainted the screen
black and white; the follow-up resize nudge only rescues full-screen
TUIs that fully repaint on SIGWINCH - inline agents (claude, omp) never
repaint their history, so everything stayed monochrome until new output
arrived.
Track attributes per cell and replay them:
- cell = rune + attr (16/256/truecolor fg+bg, bold/dim/italic/
underline/blink/reverse/strike), stamped from the terminal's current
SGR state
- a real SGR parser, including colon sub-parameter forms (38:5:196,
38:2::r:g:b, 4:0) and a 58 underline-color skip
- back-color-erase: erases, scroll-revealed rows, and inserted blanks
fill with the current background so colored bars replay intact;
resize keeps bg-colored blank rows the same way Redraw paints them
- Redraw repaints each cell with its original attributes (reset
prefix, per-run transitions, reset before the cursor park)
Capture/peek stays plain text by contract, and history stays plain
rowText - scrollback replays uncolored; only the visible screen carries
attributes.
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Jun 13, 2026
…oll and arrows (#28) Reported against v0.2.1: on a session's first launch scroll and arrow keys work, but after detach+re-attach (or resume) they go dead. Root cause, same family as #24 (which replayed SGR colors): the vterm captured screen content but discarded the agent's input-affecting DEC private modes. setPrivateMode treated mouse tracking, bracketed paste, and cursor visibility as "no effect on captured text" and never tracked application cursor keys (DECCKM ?1) or keypad mode at all; Redraw emitted only SGR + content + cursor position. On first attach the agent's mode setup flowed live through the PTY to the attached client, so it worked. On detach the attach client resets those modes; on re-attach the host sends only Redraw(), leaving the client in default mode while the still-running agent expects application-cursor (SS3) arrows and mouse reporting -- so arrows are ignored and the wheel does nothing (v0.2.1's ?1007 change removed the wheel->arrow fallback that had masked it). The vterm now tracks the input/cursor-affecting modes (DECCKM ?1, mouse ?1000/1002/1003 + focus ?1004 + encodings ?1005/1006/1015, bracketed paste ?2004, cursor visibility ?25, application keypad ESC=) and Redraw replays the ones that differ from their power-on default, before the grid content, so a re-attaching or resuming client lands in the agent's expected state. Capture stays plain text; alt-screen and SGR replay are unchanged. Adds unit coverage for each replayed mode (incl. default suppression, toggle-off, RIS reset, alt-screen, ordering) and an end-to-end TestReattachReplaysAgentPrivateModes that detaches and re-attaches to a live host and asserts the modes come back.
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Problem
Re-attaching to a session rendered it black and white: vterm stored bare runes and discarded SGR by design, so
Redraw(the replay a new attach client receives) repainted the screen colorless. The SIGWINCH nudge only rescues full-screen TUIs; inline agents (claude, omp) never repaint their history.Fix
Per-cell SGR tracking + attribute-aware replay:
cell = rune + attr(16/256/truecolor fg+bg, bold/dim/italic/underline/blink/reverse/strike).38:5:196,38:2::r:g:b,4:0) and58underline-color skip.Redrawrepaints each cell with its original attributes; reset-prefixed transitions; reset before the cursor park.Capture/peek stays plain text by contract; history stays plain (scrollback replays uncolored — only the visible screen carries attributes).Test plan
-racegreen; adversarially reviewed (one finding — resize/Redraw blank-row inconsistency — fixed in-branch).