perf(rig): lookahead 0.2->0.1 total, opt-in BT rfkill for gig nights

s.latency 0.1 (oLatency 0.1 on top = 0.2 total; the old padding defended
against watchdog-restart bursts, not latency). Regression check in-file:
journal late-count must stay 0, revert on any late. gig-up --bt-off/--bt-on:
a phone or BLE lamp churning wireplumber can kill the fold links — rfkill
the radio before doors.

start_and_midi.scd

@@ -417,14 +417,15 @@ StageLimiter.activate; // BatLib safety limiter on master out
 // 0.2 is SuperCollider's own documented default. Going lower is fair game — the
 // floor is whatever keeps `late` at zero under the densest thing PLN plays.
 //
-// HOW TO KNOW IF IT IS TOO LOW, now that it is countable:
-//     journalctl --user -u parvagues-sc -b --no-pager | grep -cE '\blate [0-9]'
-// Zero is the target. `tools/latency-lens.py` reports it per candidate too.
-// Match `late <digits>` and not the bare word: `late` is a substring of
-// ordinary text and a loose grep scored six hits on `metalPlate.scd`.
+// 2026-09-21: down to 0.1 (from 0.2). With the watchdog bug fixed the padding's
+// original justification is gone, and Tidal adds its own oLatency 0.1 on top
+// (BootTidal.hs, untouched), so total lookahead is 0.2 — the old SC-side number.
 //
-// Tidal adds its own oLatency per target on top (BootTidal.hs: 0.1 for
-// SuperDirt, 0.02 for the visuals target), so the total lookahead is the sum —
-// do not tune one while forgetting the other.
-s.latency = 0.2;
+// REGRESSION CHECK (must hold from the next parvagues-sc restart):
+//     journalctl --user -u parvagues-sc -b | grep -cE '\blate [0-9]'
+// Zero is the target; on ANY `late`, revert to 0.2. `tools/latency-lens.py`
+// reports it per candidate too. Match `late <digits>` and not the bare word:
+// `late` is a substring of ordinary text and a loose grep scored six hits on
+// `metalPlate.scd`.
+s.latency = 0.1;
 );

tools/gig-up.sh

@@ -49,6 +49,10 @@
 #     tools/gig-up.sh --live     # + assert a RIG exists, not just a set
 #     tools/gig-up.sh --converge # + START what is missing, then assert (implies --live)
 #     tools/gig-up.sh --quiet    # only the verdict and any failures
+#     tools/gig-up.sh --bt-off   # + rfkill block bluetooth (paired phones/BLE lamps
+#                                #   restarting the wireplumber session manager can
+#                                #   kill all audio — the fold links die)
+#     tools/gig-up.sh --bt-on    # + rfkill unblock bluetooth (undo --bt-off)
 #
 # Exit 0 = GO. Non-zero = do not start; the reasons are printed first.
 set -u
@@ -77,12 +81,15 @@ AUDIO=0
 QUIET=0
 LIVE=0
 CONVERGE=0
+BT=""
 for a in "$@"; do
   case "$a" in
     --audio) AUDIO=1 ;;
     --live) LIVE=1 ;;
     --converge) CONVERGE=1; LIVE=1 ;;
     --quiet|-q) QUIET=1 ;;
+    --bt-off) BT=block ;;
+    --bt-on) BT=unblock ;;
     -h|--help) sed -n '2,58p' "${BASH_SOURCE[0]}" | sed 's/^# \?//'; exit 0 ;;
     *) echo "gig-up: unknown option $a (try --help)" >&2; exit 2 ;;
   esac
@@ -91,6 +98,19 @@ done
 if [ -t 1 ]; then R=$'\033[31m'; G=$'\033[32m'; Y=$'\033[33m'; D=$'\033[2m'; Z=$'\033[0m'
 else R=; G=; Y=; D=; Z=; fi
 
+# BT hardening, opt-in. A paired phone or BLE lamp restarting the wireplumber
+# session manager can kill all audio (the gig-up --headphones fold links die),
+# so before doors: rfkill the radio off entirely. Default (no --bt-* flag)
+# leaves bluetooth untouched.
+if [ -n "$BT" ]; then
+  if rfkill "$BT" bluetooth 2>&1; then
+    (( QUIET )) || echo "  ${G}+${Z} bluetooth $BT-ed"
+  else
+    echo "  ${R}!${Z} rfkill $BT bluetooth failed (root needed? rfkill present?)" >&2
+    exit 2
+  fi
+fi
+
 LOG="$(mktemp -t gig-up-XXXXXX.log)"
 FAILURES=()   # one "name|fix command" per blocking failure, printed FIRST at the end
 WARNINGS=()