Summary

During normal typing in a psmux session, input periodically stalls — the cursor stops advancing, typed characters do not appear, and after ~2 seconds typing resumes and accumulated keystrokes show up. The stall happens silently with no error and self-recovers. More visible under fast or sustained typing.

Bisect

Narrowed to a single commit via binary search between a known-good 3-week-old state and current master:

• 86a7519 (2026-04-10 10:20) — works
• cb0d429 (2026-04-11 16:39) — works
• 8875bb5 (2026-04-11 19:22) — works
• c28a428 (2026-04-11 23:02) — works
• 3bf380d (2026-04-12 03:18) — reproduces the freeze
• master a138a9e — reproduces

Single-commit delta: 3bf380d "fix(paste): eliminate local paste duplication on Windows (#197)".

Root cause

3bf380d added a paste_suppress_until timestamp in src/client.rs and wired five new call sites (POST_CONFIRMED, CLIPBOARD_FALLBACK, TOP_CONFIRMED, STAGE2_TIMEOUT, Event::Paste handler) that set it to now + 2 seconds whenever a paste-shaped event is detected.

Pre-existing code (lines 2079–2107, the KeyCode::Char(c) handler) already contained a suppression check that drops typed characters while paste_suppress_until is in the future. Before 3bf380d that branch was effectively dormant because paste_suppress_until was rarely set. After 3bf380d any of the five new call sites can fire on normal typing — in particular STAGE2_TIMEOUT, which triggers when typed characters accumulate in paste_pend without a matching Ctrl+V within 300ms (i.e. the exact pattern of a user typing normally).

Once set, the suppression window silently drops every typed character for 2 seconds. That is exactly the observed symptom:

Type at fluent pace → characters accumulate in paste_pend → stage2 heuristic misclassifies them as a paste → paste_suppress_until = now + 2s → next 2 seconds of typing silently dropped → window expires → typing resumes, accumulated keystrokes surface.

Why it doesn't reproduce everywhere

• Requires typing fast enough for paste_pend to fill before a 300ms quiet period — slow single-finger typing may not trip it.
• Pastes themselves still work, because the paste content is sent before paste_suppress_until is set.

Environment

• psmux master (HEAD a138a9e)
• Windows 11, pwsh 7.x, PSReadLine 2.4.5, Windows Terminal 1.23.x
• Reproduces locally and over RDP.

Related

• Supersedes closed discussion in Fast typing still drops frames after #225: three remaining causes in the push pipeline #233, Regression: cursor-ahead-of-chars + typing freeze since commit 6bcb9f5 (PR #194 scroll_pane_scrollback) #236.
• The 2-second window traces to PR ctrl+v freezes the terminal over SSH #197 (paste duplication fix).