Sliding-window scan over single-char digit input events. A run of
NUMPAD_RUN_MIN (4) consecutive digit events whose pairwise IATs are
all ≤ NUMPAD_FAST_IAT_S (50ms) → detected. Otherwise → not_detected.
Skips below NUMPAD_MIN_TYPED_CHARS (50) typed chars. Confidence cap
0.50 per the registry's weak-signal flag.
ANTI authorised dropping the PII boundary for this primitive. ctx
gains typed_unigram_counts / typed_bigram_counts / typed_letter_count
populated during the existing single-pass input walk (paste-class
events excluded).
Two-axis classifier:
* layout-artefact unigrams take priority — q rate above floor with
low English saturation → azerty; z above floor with y below → qwertz
* fallback to English-bigram saturation: ≥ floor → qwerty, else other
Sample-size floor 200 typed letters; bigram histogram capped at
top-64 to bound memory. Confidence cap stays moderate (0.40-0.55) —
heuristic discriminator.
Searches ANSI-stripped output for LANG / LC_ALL / LC_CTYPE envvar
substrings emitted by env / locale / printenv. Highest-priority key
wins (LC_ALL > LANG > LC_CTYPE); POSIX value normalised to BCP-47:
en_US.UTF-8 → en-US, pt_BR.UTF-8 → pt-BR, C/POSIX → und. Free-string
registry value emitted directly.
PII discipline: only the parsed locale value enters observations;
surrounding output is read once for matching and dropped.
Scans RAW output (multiplexer escapes are themselves ANSI; never
strip first) for tmux markers (DCS passthrough, focus-reporting,
window-title with tmux marker) and screen markers (DCS, screen-OSC).
Detected → tmux/screen at 0.85; otherwise → none at 0.55. Skips
emission entirely when no commands — silence on a pure-echo or
empty session, per the smoke gates.
When both detected (nested mux), prefer tmux.
