0.9.1 Windows input rework breaks empty-bracketed-paste decode: clipboard image bridge on ctrl+v silently dead in herdr --remote (Windows Terminal)

Summary

On Windows, clipboard image paste into herdr --remote panes via the default ctrl+v binding silently stopped working after upgrading the client to 0.9.1. The same setup works when keys.remote_image_paste is rebound to a raw key (e.g. f8), and it works again on ctrl+v after unbinding ctrl+v from Windows Terminal's own paste action. On 0.9.0-era clients the default ctrl+v binding worked fine.

Environment

• Client: Windows 11 (build 26200), Windows Terminal (ctrl+v explicitly bound to Terminal.PasteFromClipboard), PowerShell 7.6.6
• herdr client 0.9.1 (stable); remote servers on macOS (macmini / macbook), both herdr 0.9.1
• Bridge triggers verified against herdr-client.log / remote herdr-server.log (staged client clipboard image ...)

Symptom

With defaults (keys.remote_image_paste = "ctrl+v"), pressing ctrl+v in a --remote attach window with an image on the clipboard does nothing at all:

• no bridging local image to remote server line in the client log
• no clipboard image paste trigger received, but local clipboard has no image line either
• no staged client clipboard image on the remote server

So the trigger function never matches — the keypress/paste never arrives as a bridging candidate. Everything else is healthy: the same client bridges fine via source="file drop", and rebinding to f8 produces immediate, correctly-sized stagings.

Mechanism (as far as I can trace it)

1. Windows Terminal consumes ctrl+v itself (bound to Terminal.PasteFromClipboard), so herdr never sees a ctrl+v key event.
2. Herdr's designed path for WT is the empty-bracketed-paste side channel: WT pasting an image-only clipboard emits ESC[200~ESC[201~, which decodes to Paste { text: "" }, and should_bridge_clipboard_image_events treats an empty paste as an image-paste trigger.
3. That empty-paste decode worked on 0.8.2/0.9.0 clients (I have bridging local image ... source="clipboard paste" log lines from those versions) and stopped with the 0.9.1 client.
4. src/client/clipboard_images.rs (the trigger) is byte-identical between v0.9.0 and master — I diffed it. What did change massively in 0.9.1 is the Windows input decoder: src/client/input/windows_vti.rs grew from 3243 to ~3899 lines across 25 hunks (new default-mouse-candidate machinery that can swallow key records, several flush_timeout() → flush_interrupted() swaps, framer drain changes). An empty paste has no content bytes, so it is the most fragile case: if any record boundary takes a semantic/flush path that discards pending framer state, the empty paste never completes and no Paste event is emitted.

This is the same 0.9.1 input rework that fixed Alt+V pass-through (#3702) and reportedly regressed Shift+Enter (#3269 / the Win32 input reporting hotfix).

Workarounds (both confirmed working)

• Rebind: [keys] remote_image_paste = "f8" in config.toml — raw function keys bypass the terminal paste action entirely.
• Unbind ctrl+v in Windows Terminal settings (move Terminal.PasteFromClipboard to ctrl+shift+v): ctrl+v then reaches herdr as a real key event, and the default ctrl+v combo trigger (the key-combo branch of should_bridge_clipboard_image_events) fires normally. This restores the muscle-memory key.
• ctrl+alt+v does not work as a middle ground (chord arrives mangled — AltGr/IME territory).

Fix directions

1. Restore empty-bracketed-paste decoding on the Win32 record path (the 0.9.1 windows_vti.rs rework looks like the regression window; bisecting the 25 hunks around PasteAwareKey / flush_interrupted / default-mouse-candidate handling should find it).
2. Consider allowing keys.remote_image_paste to accept multiple bindings, so users can keep both ctrl+v and a fallback raw key.
3. Document the WT ctrl+v interaction on the Windows docs page (that image paste needs ctrl+v unbound in WT, or a non-terminal-consumed key).

Related

• #3702 (Alt+V arrives as bare v on WT — fixed by the same 0.9.1 rework that appears to break this)
• #4230 (conhost: ctrl+v / ctrl+shift+v paste broken without WT)
• #4005 (multi-attach clipboard routing)