Add ANSI.replay to collapse captured repaints - #625
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Generate Unicode 17 wide-character ranges from pinned Unicode data and keep the width helper internal so existing layout APIs retain their current behavior. Assisted-By: devx/b840c1e6-d979-473d-9216-a53477380bf1
Apply viewport-independent terminal controls to a line grid so captured spinner and progress-bar repaints collapse to their final output. Parse streams with a VT-style state machine, discard presentation and alternate-screen content, and use the internal Unicode terminal-width helper for correct wide-glyph cursor placement without changing existing layout APIs. Co-authored-by: River <river@shopify.com> Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Assisted-By: devx/b840c1e6-d979-473d-9216-a53477380bf1
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Assisted-By: devx/b840c1e6-d979-473d-9216-a53477380bf1
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Summary
Add
ANSI.replay, which turns a captured terminal stream into the text left after cursor-driven repaints settle.Spinners and progress bars repeatedly redraw the same screen area. A log capture stores every frame, and
ANSI.strip_codesonly removes escape sequences; it does not apply cursor movement or erasure. Replay applies the viewport-independent controls instead, so those frames collapse to the final output a developer saw.For example, Shopify's dev CLI attaches
dev upoutput to error reports. A representative 450 KB capture replays to 41 KB of useful text.What replay models
Presentation sequences and control-string payloads are consumed without producing text. Operations that require a viewport, such as absolute screen positioning and display erasure, are ignored because a capture does not record scrolling and therefore cannot map screen coordinates back to buffer rows.
The stream parser follows the VT500 state-machine shape, including malformed, aborted, embedded-control, and cut-off sequences. Resource limits apply only to rows and columns conjured by control sequences; ordinary captured output remains unbounded.
Scope boundary
This PR deliberately leaves the existing
ANSI.strip_codes,ANSI.printing_width, Truncater, and Wrap behavior unchanged. Replay needs terminal-accurate column widths, so it includes a private Unicode 17 width helper and generated data, but existing layout APIs do not adopt it here.Follow-up #624 aligns stripping, measurement, truncation, and wrapping on top of this PR. Replay and stripping still have different semantics: replay interprets cursor controls, while stripping only removes recognized sequences.
Limitations
The
[1234]pids that are inserted into stream sometimes break ordering, so they may pick up extra characters (e.g.,[12✅4]). This is acceptable, as the replayed logs are just for streamlined troubleshooting context.