Files
Netcatty/components/terminal/autocomplete/ghostTextConsistency.ts
T
陈大猫 f4aa6ddb46 fix #1013: stop ghost text from drawing over untracked echoed input (#1042)
Inline (ghost-text) suggestions render suggestion.substring(trackedInput.length)
after the cursor, where trackedInput is a client-side reconstruction of the
command line (buffer heuristics + keystroke prediction, to mask SSH echo
latency). On hosts with non-standard echo — hardware bastion hosts / network OS
like `ecOS#` (#1013, previously #756 / #906) — that reconstruction drifts and
the ghost gets painted over characters the user already typed (`int` + ghost
`terface` -> `intterface`).

Add a fail-safe consistency check: on each post-echo render, if the real
terminal line before the cursor contains the tracked input followed by more
untracked, non-whitespace characters (reality is AHEAD of what we tracked),
hide the ghost instead of drawing it over real text. SSH echo latency is the
opposite case (the line is a prefix-behind of the tracked input) and is
deliberately not flagged, so the ghost stays responsive on slow links. The
check is ASCII-only (wide-char column mapping is ambiguous) and fail-open, so
it can only ever suppress a ghost that would otherwise corrupt — never change
correct behaviour.

This converts the recurring "ghost shows already-typed characters" bug into
"ghost simply doesn't show" on devices we can't track reliably.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-21 15:40:35 +08:00

43 lines
2.0 KiB
TypeScript

/**
* Fail-safe consistency check for inline (ghost-text) suggestions.
*
* Ghost text renders `suggestion.substring(trackedInput.length)` after the
* cursor, where `trackedInput` is what the client thinks the user has typed.
* On hosts with non-standard echo (hardware bastion hosts / network OS such as
* `ecOS#`, issue #1013, previously #756 / #906) that tracked value drifts out
* of sync with what is actually on the terminal line, and the ghost ends up
* painted over characters the user already typed (`int` + ghost `terface` →
* `intterface`).
*
* This detects the one direction that produces visible corruption: the real
* line being AHEAD of the tracked input (it contains the tracked input
* followed by more, untracked characters). SSH echo latency is the opposite
* case — the line is a prefix-behind of the tracked input — and is
* intentionally NOT flagged, so the ghost stays responsive on slow links.
*
* Returns true when the caller should hide the ghost.
*/
export function lineHasUntrackedTrailingInput(
trackedInput: string,
lineBeforeCursor: string,
): boolean {
// Single chars match too loosely to judge reliably; let them through.
if (trackedInput.length < 2) return false;
// Column↔string mapping is only unambiguous for narrow (ASCII) input, so the
// existing wide-char (CJK / emoji) handling is left untouched.
if (!/^[\x20-\x7e]+$/.test(trackedInput)) return false;
// Use the last occurrence so a prompt or command that repeats the same token
// earlier on the line doesn't shadow the freshly-typed input.
const idx = lineBeforeCursor.lastIndexOf(trackedInput);
if (idx < 0) {
// Tracked input isn't on screen yet — the echo is still catching up
// (latency). Keep the ghost; reality being behind never corrupts.
return false;
}
// Non-whitespace characters between the tracked input and the cursor mean the
// device echoed input we never tracked → the ghost would overlap real text.
return lineBeforeCursor.slice(idx + trackedInput.length).trimEnd().length > 0;
}