[BUG] VS Code extension: caret renders 2 positions back after typing pause, hides last chars; next keystroke restores (display-only)

Environment

• Claude Code VS Code extension: 2.1.281 (darwin-arm64), auto-updated ~1h before report
• VS Code: 1.139.0 (Universal), commit 2242ebb, built 2026-09-22
• Electron 43.6.0 / Chromium 150.0.7871.250
• macOS 26.6.2 (Darwin arm64 25.6.0), Apple Silicon
• Also installed: GitHub Copilot 1.0.85

What happens

In the prompt input box, when I pause typing:

1. The caret visibly jumps back two positions and covers/hides the last two characters typed.
2. On the next keystroke, the caret jumps to one past the original position and all characters reappear — including the one just typed.

Display-only — text is not lost

Confirmed by sending a message after the glitch occurred without correcting anything: the submitted text was intact (no missing or extra characters).

Why it matters anyway

It looks like characters (usually trailing spaces) were deleted, so the natural reaction is to retype them — which then produces genuinely doubled spaces in the submitted prompt. The glitch is cosmetic, but it induces real input errors.

Frequency

Intermittent; seems to be happening more often recently. Both the extension (2.1.281) and VS Code (1.139.0, new Chromium) updated within the last two days, so it's not yet clear which introduced it.

Possibly related

#14589 (extra spaces inserted during input). That report describes real whitespace insertion; this one is a render/caret desync with intact underlying text — possibly the same root cause, possibly what some #14589 reporters are actually seeing.

Guess at cause (unverified)

Looks like a stale render of an overlay/caret layer on an idle or debounce tick (draft save / autocomplete?), resynced by the next input event.