Problem:
Terminal probes sent with `nvim_ui_send()` can reach more than one stdout TTY
UI. Probes with a known TTY UI owner should not accept `TermResponse`s from
unrelated UI channels.
Solution:
Thread the existing `chan` filter through owned terminal probes. This covers
startup/attach background detection, fallback truecolor detection, and
`vim.tty.query()` forwarding opts to `vim.tty.request()`.
Note: Not every terminal escape path is updated here. I only passed `chan` when
the caller already knows which TTY UI owns the probe. For example, this does
not include:
- (Followup) OSC 52 (system clipboard) detection. It needs to capture the
`UIEnter` channel. Adding `{ chan = ... }` only to the nested query would be
half a fix.
- OSC 52 _paste_ is left global because the provider callback does not have
a UI channel (paste is invoked without a ui channel/tty ui object).
Problem: Attach-time terminal probes cannot distinguish responses from
different attached UIs.
Solution: Identify the UI by RPC channel id in `TermResponse` and make
`vim.tty.request()` filter responses by channel.
Problem:
`nvim_create_autocmd` is too verbose and its `callback` requires extra
"nesting".
Solution:
Introduce `nvim_on`. Start using it internally. Then we can get a feel
for how it should look before making it public.
Problem:
- Windows users can't use terminfo to configure their terminal
capabilities. #37274
- Terminfo definitions sometimes get out of date or are simply
inaccurate.
- Eventually, we may want to drop terminfo, relying primarily on
built-in definitions. Users will still need some flexibility.
Solution:
Support $NVIM_TERMDEFS environment variable, which is JSON data that
defines "terminfo" definitions that override our builtin terminfo.
Problem:
- Various `TermRequest` handlers which all do similar things.
- `tty.query` is specific to `XTGETTCAP DCS`, can't be reused for other kinds of terminal queries.
Solution:
Provide `tty.request()`.
