When App's 50ms flush watchdog fires mid-CSI during a render stall, an
SGR mouse report (ESC[<btn;col;row M/m) is split across stdin chunks: the
tokenizer force-emits the buffered prefix and resets to ground, so both
the prefix and the ESC-less remainder reach InputEvent as nameless tokens.
The previous guard only matched a full `[<\d+;\d+;\d+[Mm]` fragment, so
the flushed prefixes (`ESC[<0;35;`) and the 1-/2-field and leading-`;`
tails (`46M`, `35;46M`, `;46M`) still leaked into the composer as
`46M35;40M...` during long sessions.
Replace the three would-be narrow regexes with one consolidated rule that
covers every split position. A `(?=...\d)` lookahead keeps typed `<`, `[`,
`;`, and `M` safe (no coordinate digit), and the embedded M/m terminator
in the param class leaves stuck-together fragments / prose intact. The
existing `!keypress.name` gate continues to protect real keystrokes, which
arrive one char per chunk with a name set.
Supersedes #29337 (covers the prefix-leak and leading-`;`/1-/2-field tail
cases that PR's two added guards missed).
Brooklyn Nicholson
01c010e233