Fix 6 client-server mode bugs (display-message, mouse, popup, paste, right-click) by ToxMox · Pull Request #118 · psmux/psmux

ToxMox · 2026-03-17T02:30:20Z

I ran into these issues while using psmux in client-server mode from VS Code today and ended up forking and fixing them for myself. Figured they might help others out too. Thanks for the awesome work on psmux!

Context

When psmux runs in client-server mode (psmux attach from VS Code terminal or Windows Terminal), several features silently break because the client and server have separate input/rendering paths. These fixes address the most impactful issues for multi-client workflows and VS Code terminal usage.

Fixes

display-message

The rendering infrastructure existed (server serializes status_message to JSON, client renders it on the status bar with message_style) but the DisplayMessage handler only expanded the format string and returned it — it never set app.status_message. One-line fix.

Mouse multi-client tracking

With multiple clients attached at different terminal sizes, mouse clicks on the status bar only worked in whichever client last resized. latest_client_id was only updated on ClientAttach and ClientSize — not on mouse events. Added client_id to all 10 mouse/scroll CtrlReq variants. The server now recomputes effective window size from the clicking client's dimensions before processing coordinates.

Popup race condition

display-popup with fast commands (e.g. echo test) produced blank popups. The PTY reader thread hadn't processed any output before the first frame was serialized to the client. Added a 50ms delay after PTY spawn to let the reader thread populate the vt100 parser.

Paste fragmentation (VS Code terminal)

Large pastes in VS Code's terminal arrived as multiple [Pasted text #N] chunks instead of one. Root cause chain:

ConPTY with VTI disabled strips bracket paste markers, delivering paste as individual KEY_EVENT records
The client's paste_pend burst detector entered stage2 but timed out at 300ms mid-paste (ConPTY delivers text over ~1 second)
Ctrl+V Release triggered an immediate flush before ConPTY finished injecting characters
Right-click clipboard paste sent the full content, then ConPTY also injected the same text as key events — producing a duplicate
Non-ASCII characters (em-dashes, etc.) triggered immediate flush as "normal text" instead of accumulating

Fixes: Ctrl+V Release no longer flushes immediately — promotes to stage2 for growth detection so ConPTY can finish delivery; right-click clipboard paste suppresses duplicate ConPTY key events for 2s (discards text keys during the suppression window to prevent leaked Enter/Tab); large non-ASCII buffers (>=20 chars) enter stage2 instead of being treated as IME input; added growth detection to stage2 timeout so ongoing pastes aren't split.

Right-click copy triggers unwanted paste

In VS Code with "smart copy/paste" right-click behavior, highlighting text and right-clicking would copy the selection AND paste the clipboard content. VS Code injects clipboard content as key events after the copy action. Uses the same 2s suppression window with full text-key filtering.

Clipboard line ending normalization

Right-click paste produced double-spaced text because the Windows clipboard preserves \r\n line endings. Now normalizes \r\n to \n and trims trailing newlines from clipboard reads.

Test plan

display-message "hello" from command prompt shows in status bar
Two clients attached with different sizes — mouse clicks work in both
display-popup -E "echo hello" renders content (not blank)
Ctrl+V paste of 40+ lines in VS Code terminal arrives as single chunk
Right-click paste in VS Code arrives as single chunk, matching Ctrl+V formatting
Highlight + right-click copies without pasting or inserting carriage returns
Paste containing non-ASCII (em-dashes, backticks) arrives as single chunk
ESC key works normally (not swallowed or delayed)
Normal typing, IME input, and Ctrl+V in Windows Terminal remain unaffected

1. display-message: Set app.status_message so messages appear on the status bar (tmux parity). The rendering infrastructure existed but the DisplayMessage handler never populated the field. 2. Mouse client tracking: Add client_id to all mouse/scroll CtrlReqs. On mouse events, update latest_client_id and recompute effective window size before processing coordinates. Fixes status bar clicks breaking when multiple clients have different terminal sizes. 3. Popup race condition: Add 50ms delay after PTY spawn before entering PopupMode, giving the reader thread time to populate the vt100 parser. Prevents empty/invisible popups for fast commands. 4. Paste coalescing: Increase paste chunk size from 512 to 4096 bytes. Add 50ms coalescing window for bracket paste events in embedded mode to merge rapid successive paste fragments from VS Code's ConPTY.

Three fixes for paste fragmentation: 1. Ctrl+V paste: Don't flush immediately on paste_confirmed (Ctrl+V Release). ConPTY is still injecting chars. Promote to stage2 and let growth detection wait for delivery to finish. 2. Right-click paste: After sending clipboard content, suppress paste_pend for 2s to discard duplicate key events that VS Code injects through ConPTY. 3. Non-ASCII paste: Allow large (>=20 char) buffers with non-ASCII into stage2 — they're pastes, not IME. Only apply IME exclusion for small (3-19 char) buffers. Also adds bracket paste detection state machine and coalescing to client-server mode (ported from embedded mode in app.rs).

When highlighting text and right-clicking to copy, VS Code's "smart copy/paste" also injects clipboard content as key events through ConPTY. Suppress paste_pend for 2s after the copy-on-right-click path to discard those duplicate key events.

ConPTY strips bracket paste markers when VTI is disabled, so the state machine never fires in client-server mode. It was added before the real paste fix (paste_pend improvements) was identified. Removing it fixes ESC key being swallowed by the detector's 5ms buffering.

- Normalize \r\n to \n in clipboard reads (Windows clipboard preserves \r, causing double-spaced pastes) - Trim trailing newlines from clipboard paste to avoid blank lines - During paste suppression window, discard text key events (Char, Enter, Tab) that VS Code injects as ConPTY echoes — prevents carriage returns leaking into prompt after highlight+right-click copy

ToxMox · 2026-03-17T03:13:22Z

Apologies for the extra commits after opening — I was still testing edge cases when I submitted. The last two commits fix:

ESC key regression: Removed the bracket paste detection state machine from client mode. ConPTY strips bracket paste markers when VTI is disabled, so it never fired — but it was buffering ESC keys for 5ms and sometimes swallowing them.
Clipboard line endings: Right-click paste was double-spacing text because the Windows clipboard preserves \r\n. Now normalizes to \n and trims trailing newlines. Also tightened the paste suppression window to discard leaked Enter/Tab key events that VS Code injects after a right-click copy.

Should be stable now — tested right-click paste, Ctrl+V paste, highlight+right-click copy, ESC, and normal typing.

psmux · 2026-03-18T11:59:58Z

Hey @ToxMox, thanks for the incredibly thorough analysis! I went through each of the 6 bugs you identified and can confirm every single one is real — great detective work.

I've independently fixed all 6 in commit ffcf3d3:

1. display-message — Added a set_status_bar flag to the DisplayMessage CtrlReq. The handler now sets app.status_message when -p isn't used. The list-sessions -F path passes false so it doesn't pollute the status bar.

2. Mouse multi-client — Added client_id (u64) to all 10 mouse/scroll CtrlReq variants. The server now updates latest_client_id before processing each mouse event, so coordinate resolution uses the clicking client's dimensions.

3. Popup race — Added a 50ms thread::sleep after PTY spawn + reader thread creation, before setting the popup mode. This gives the reader thread time to process initial output before the first frame serializes.

4. Paste fragmentation — Added growth detection to the stage2 timeout: if paste_pend.len() increased since the last 300ms check, the timer resets instead of splitting. Also added a path for large non-ASCII buffers (≥20 chars) to enter stage2 instead of being treated as IME input.

5. Right-click copy suppression — After a right-click copy, text key events are now suppressed for 2 seconds via paste_suppress_until. This prevents VS Code's ConPTY from injecting duplicate clipboard content.

6. Clipboard CRLF — read_from_system_clipboard() now normalizes \r\n → \n before returning.

I'm closing this PR since the fixes are already on master, but I really appreciate you taking the time to identify and document all of these — the root cause analysis in your PR description was spot-on. Cheers!

… right-click, CRLF) Fix 6 bugs in client-server mode reported in #118: 1. display-message: handler now sets app.status_message when not using -p flag, so messages actually appear on the status bar. 2. Mouse multi-client tracking: all 10 mouse/scroll CtrlReq variants now carry client_id. Server updates latest_client_id on mouse events so coordinate processing uses the clicking client's dimensions. 3. Popup race condition: added 50ms delay after PTY spawn in display-popup so the reader thread can populate the vt100 parser before the first frame is serialized to clients. Prevents blank popups with fast commands. 4. Paste fragmentation: added growth detection to stage2 timeout. If the paste_pend buffer grew since the last check, the timeout is extended instead of splitting the paste. Large non-ASCII buffers (>=20 chars) now enter stage2 instead of being flushed as IME input. 5. Right-click copy paste suppression: after right-click copy, text key events are suppressed for 2s to prevent VS Code ConPTY from injecting duplicate clipboard content as key events. 6. Clipboard CRLF normalization: read_from_system_clipboard() now normalizes Windows CRLF line endings to LF, preventing double-spaced paste output. Also includes the parse_command_line \\\\ escape fix from #123.

@ToxMox

Fix 6 bugs in client-server mode reported by @ToxMox in #118: 1. display-message: handler now sets app.status_message when not using -p flag, so messages actually appear on the status bar. 2. Mouse multi-client tracking: all 10 mouse/scroll CtrlReq variants now carry client_id. Server updates latest_client_id on mouse events so coordinate processing uses the clicking client's dimensions. 3. Popup race condition: added 50ms delay after PTY spawn in display-popup so the reader thread can populate the vt100 parser before the first frame is serialized to clients. Prevents blank popups with fast commands. 4. Paste fragmentation: added growth detection to stage2 timeout. If the paste_pend buffer grew since the last check, the timeout is extended instead of splitting the paste. Large non-ASCII buffers (>=20 chars) now enter stage2 instead of being flushed as IME input. 5. Right-click copy paste suppression: after right-click copy, text key events are suppressed for 2s to prevent VS Code ConPTY from injecting duplicate clipboard content as key events. 6. Clipboard CRLF normalization: read_from_system_clipboard() now normalizes Windows CRLF line endings to LF, preventing double-spaced paste output. Also fixes parse_command_line backslash escape reported by @schgoo in #123. The parser now recognises \\ as an escape sequence inside double quotes (producing a single \), preventing the closing quote from being consumed when the client sends send-text "\\". Co-investigated-by: @ToxMox (#118) Co-investigated-by: @schgoo (#123)

Brings 17 upstream commits into ohboy-builds: - fix: warm claim race condition (psmux#136) - fix: client_prefix flag, window_zoomed_flag (psmux#125, psmux#126) - fix: Shift+Enter/Ctrl+Enter modifiers, paste normalization (psmux#131, psmux#132) - fix: backslash escape, 6 client-server bugs (psmux#118, psmux#123) - fix: -f global option (psmux#119) - fix: set-hook replace/remove, zoomed navigation wrap (psmux#133, psmux#134) - fix: TERM env var mapping, hyphenated option leak (psmux#137) - feat: bell/activity/silence monitoring, allow-rename, update-environment - feat: vim-style bind-key C-hjkl pane navigation (psmux#130) - feat: XDG plugin path support (psmux#135) - feat: auto-generate changelog in release workflow - refactor: move Rust tests to tests-rs/ directory - refactor: rich test dashboard Also applies ohboy-builds stashed changes: - Remove claude-code-fix-tty (Claude Code now auto-detects $TMUX) - Migrate env::set_var to safe crate::util::set_env wrappers (Rust 1.83) - Selection clamp to pane boundaries in copy mode - Fix clippy warnings in forked crates (vt100-psmux, portable-pty-psmux)

@ToxMox

Fix 6 bugs in client-server mode reported by @ToxMox in psmux#118: 1. display-message: handler now sets app.status_message when not using -p flag, so messages actually appear on the status bar. 2. Mouse multi-client tracking: all 10 mouse/scroll CtrlReq variants now carry client_id. Server updates latest_client_id on mouse events so coordinate processing uses the clicking client's dimensions. 3. Popup race condition: added 50ms delay after PTY spawn in display-popup so the reader thread can populate the vt100 parser before the first frame is serialized to clients. Prevents blank popups with fast commands. 4. Paste fragmentation: added growth detection to stage2 timeout. If the paste_pend buffer grew since the last check, the timeout is extended instead of splitting the paste. Large non-ASCII buffers (>=20 chars) now enter stage2 instead of being flushed as IME input. 5. Right-click copy paste suppression: after right-click copy, text key events are suppressed for 2s to prevent VS Code ConPTY from injecting duplicate clipboard content as key events. 6. Clipboard CRLF normalization: read_from_system_clipboard() now normalizes Windows CRLF line endings to LF, preventing double-spaced paste output. Also fixes parse_command_line backslash escape reported by @schgoo in psmux#123. The parser now recognises \\ as an escape sequence inside double quotes (producing a single \), preventing the closing quote from being consumed when the client sends send-text "\\". Co-investigated-by: @ToxMox (psmux#118) Co-investigated-by: @schgoo (psmux#123)

ToxMox added 5 commits March 16, 2026 22:25

psmux closed this Mar 18, 2026

MattKotsenas mentioned this pull request May 16, 2026

Clean up the Windows clipboard layer: adopt clipboard-win, propagate -w consistently, rehome the newline normalization #298

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Fix 6 client-server mode bugs (display-message, mouse, popup, paste, right-click)#118

Fix 6 client-server mode bugs (display-message, mouse, popup, paste, right-click)#118
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ToxMox commented Mar 17, 2026 •

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ToxMox commented Mar 17, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Context

Fixes

display-message

Mouse multi-client tracking

Popup race condition

Paste fragmentation (VS Code terminal)

Right-click copy triggers unwanted paste

Clipboard line ending normalization

Test plan

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ToxMox commented Mar 17, 2026

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psmux commented Mar 18, 2026

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ToxMox commented Mar 17, 2026 •

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