tools: add --reach-only, so a caller that just needs the menu does not run the round trip

The ja DIFFICULTY capture failed because focus_persistence.py's round trip --
menu, B to title, A back -- did not return, leaving the game off-menu, and the
sweep that followed timed out with nothing to work with. Arriving at the menu is
the cheap part; the round trip is that probe's own experiment and is not every
caller's.

--reach-only stops once the menu is reached, and the session script passes it
through REACH_ONLY.

Committed before running.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v

tools/re-capture/extras_focus_session.sh

@@ -20,6 +20,6 @@ cd /sylph-home/re
 nohup run-canary --apu=sdl --log_mask=13 --log_level=2 \
   --logged_profile_slot_0_xuid="$XUID" </dev/null >"$LOG" 2>&1 &
 # reach the title and the menu with the probe that already does it
-python3 "$SD/focus_persistence.py" "$LOG" "$OUT/reach" 900 >"$OUT/reach.log" 2>&1
+python3 "$SD/focus_persistence.py" "$LOG" "$OUT/reach" 900 ${REACH_ONLY:+--reach-only} >"$OUT/reach.log" 2>&1
 echo "-- reached the menu; now the EXTRAS question --"
 python3 "${SWEEP:-$SD/extras_focus_persistence.py}" "$LOG" "$OUT" 600

tools/re-capture/focus_persistence.py

@@ -150,6 +150,16 @@ while True:
                 print(f"🔴 no main-menu ring row in the F1 frame (y={v[0]}) — stopping", flush=True); break
             print(f"[{el:7.1f}s] MENU (glyph {c})  F1 = {NAMES[F1]}   ring "
                   + " ".join(f"{x:5.0f}" for x in v), flush=True)
+            # --reach-only: stop here. A caller that just needs the game SITTING on
+            # the menu should not run the round trip -- on 2026-08-31 a ja capture
+            # of DIFFICULTY failed because this probe's B->title->A leg did not come
+            # back, leaving the game off-menu, and the sweep that followed had
+            # nothing to work with. Arriving is the cheap part; the round trip is
+            # this probe's own experiment and is not every caller's.
+            if "--reach-only" in sys.argv:
+                print("REACHED THE MENU (--reach-only, no round trip)", flush=True)
+                p.kill()
+                sys.exit(0)
             # 🔴 Run 1 pressed DOWN twice through pad.py with NO delivery
             # confirmation and the guest logged vk=5811 exactly ONCE. A and B
             # were confirmed; the d-pad was not, so the run was unreadable.