re: kill-free HUD route for REMAINING OB; big-endian u32 assumption refuted

The correlation route is gated on marked-fighter kills, which the pilot manages
at about two per five minutes. ob_read.py already reads the counter off the
screen, so ob_by_hud.py matches the displayed value against memory directly and
needs no kills at all: screenshot, read the digits, keep heap words equal to that
value, intersect across readings.

Four readings at value 4 narrowed 6156 candidates to 4312, the expected slow
drift. Then the HUD read 11 and the intersection collapsed to zero. A word
holding this counter must equal 4 at the first four samples and 11 at the last,
and none does, so within the entity heap read as big-endian u32 the counter does
not exist. It may be u16, u8, little-endian, or outside that region. Both
previous hunts assumed big-endian u32 there, so this eliminates the assumption
rather than merely failing to find anything.

The displayed value also went up, from 4 to 11 over about 340 seconds. A pure
countdown of remaining marked targets should not rise, and the deployment work
says phase 1 gains no new participants. Three readings are possible and none is
tested: the cell being read is not REMAINING OB, the digits are misread, or the
counter genuinely counts something that can increase. The two clean readings
scored 0.95 to 0.98 against their templates, but 4 and 11 use only digits that
are in the strip, which is exactly the selection effect that would hide a wrong
reading -- the template set covers 0 1 2 4 8 only, and most samples came back
unreadable.

Next is widening the scan to u16 and u8 and to little-endian, and beyond the
entity heap, which is a change to one function and costs no combat. Extending
ob_digits.png with the missing digits would also raise the sample yield, since
only two of eleven readings in a 480 s run were usable.

tools/re-capture/ob_by_hud.py

@@ -0,0 +1,71 @@
+#!/usr/bin/env python3
+"""Locate REMAINING OB from the HUD value instead of from kill events.
+
+The correlation route works but needs marked-fighter kills, and the pilot gets
+about two per five minutes (remaining-ob-hunt.md). The HUD already shows the
+number, and ob_read.py already reads it, so match the displayed value against
+memory directly -- no kills required.
+
+Each reading intersects: keep heap words equal to the value the HUD shows at
+that moment. A second reading at a DIFFERENT value collapses the set hard; even
+repeated readings at the same value help, since unrelated words drift.
+"""
+import os, sys, time, subprocess, collections
+sys.path.insert(0, __file__.rsplit('/', 1)[0])
+import gmem, gworld
+import numpy as np
+import ob_read
+
+LO, HI = 0xBD000000, 0xBE000000
+SHOT = '/tmp/ob_hud.png'
+
+def region(fd):
+    lo, hi = gmem.va_to_off(LO), gmem.va_to_off(HI)
+    out, pos = bytearray(), lo
+    while pos < hi:
+        n = min(1 << 24, hi - pos); out += os.pread(fd, n, pos); pos += n
+    return np.frombuffer(bytes(out), dtype='>u4'), lo
+
+def hud_value():
+    subprocess.run(['screenshot', SHOT], capture_output=True, timeout=60)
+    try:
+        txt, scores = ob_read.read(SHOT)
+    except Exception as e:
+        return None, str(e)
+    t = (txt or '').strip()
+    if not t.isdigit(): return None, 'unreadable %r' % txt
+    return int(t), 'scores %s' % (scores,)   # ob_read returns tuples, not floats
+
+def main():
+    secs  = int(sys.argv[1]) if len(sys.argv) > 1 else 240
+    every = int(sys.argv[2]) if len(sys.argv) > 2 else 25
+    w = gworld.World(); fd = w.fd
+    cand = None; base = None; seen = []
+    t0 = time.time()
+    while time.time() - t0 < secs:
+        v, note = hud_value()
+        el = round(time.time() - t0)
+        if v is None:
+            print('  t=%4ds  HUD unreadable (%s)' % (el, note), flush=True)
+        else:
+            r, base = region(fd)
+            hit = set(np.nonzero(r == v)[0].tolist())
+            cand = hit if cand is None else (cand & hit)
+            seen.append(v)
+            print('  t=%4ds  HUD=%-4d words==%d: %-8d -> candidates %d  (%s)'
+                  % (el, v, v, len(hit), len(cand), note), flush=True)
+            if len(cand) <= 40 and len(set(seen)) >= 2:
+                break
+        time.sleep(every)
+    print('\nHUD values seen: %s' % sorted(set(seen)))
+    if cand and base is not None:
+        print('candidates: %d' % len(cand))
+        for i in sorted(cand)[:20]:
+            va = gmem.primary_va(base + i * 4)
+            print('   va %s' % (('%#010x' % va) if va else '?'))
+    else:
+        print('no candidates (HUD never read, or value never matched a u32)')
+    return 0
+
+if __name__ == '__main__':
+    sys.exit(main())

tools/re-capture/obhud_attach.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+set -u
+export HOME=/sylph-home/re SDL_AUDIODRIVER=dummy DISPLAY=:98
+export PYTHONPATH=/sylph-home/.local/lib/python3.12/site-packages
+SD="$(cd "$(dirname "$0")" && pwd)"
+pgrep -x xenia_canary >/dev/null || { echo "NO EMULATOR"; exit 1; }
+CFG=/tmp/nav-obhud2.json
+for try in 1 2 3; do
+  python3 "$SD/pad.py" set "rt=1" >/dev/null 2>&1 || true; sleep 3
+  python3 "$SD/pad.py" clear >/dev/null 2>&1 || true
+  if python3 "$SD/entities2.py" self 0x130 "$CFG" >/dev/null 2>&1; then
+    SYLPH_HUNT=1 SYLPH_KILL_TURRETS=1 SYLPH_KEEPOUT=1400 SYLPH_PREFER=e010 \
+      nohup python3 "$SD/pilot.py" "$CFG" "${1:-400}" </dev/null >/tmp/obhud2-pilot.log 2>&1 &
+    P=$!; echo "--- pilot re-attached"; break
+  fi
+done
+python3 "$SD/ob_by_hud.py" "${1:-400}" "${2:-25}"
+[ -n "${P:-}" ] && kill "$P" 2>/dev/null
+echo "OBHUD ATTACH DONE"

tools/re-capture/obhud_session.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+set -u
+export HOME=/sylph-home/re SDL_AUDIODRIVER=dummy DISPLAY=:98
+export PYTHONPATH=/sylph-home/.local/lib/python3.12/site-packages
+SD="$(cd "$(dirname "$0")" && pwd)"
+"$SD/launch_mission.sh" fly || { echo "BOOT FAILED"; exit 1; }
+CFG=/tmp/nav-obhud.json
+for try in 1 2 3; do
+  python3 "$SD/pad.py" set "rt=1" >/dev/null 2>&1 || true; sleep 3
+  python3 "$SD/pad.py" clear >/dev/null 2>&1 || true
+  if python3 "$SD/entities2.py" self 0x130 "$CFG" >/dev/null 2>&1; then
+    SYLPH_HUNT=1 SYLPH_KILL_TURRETS=1 SYLPH_KEEPOUT=1400 SYLPH_PREFER=e010 \
+      nohup python3 "$SD/pilot.py" "$CFG" "${1:-240}" </dev/null >/tmp/obhud-pilot.log 2>&1 &
+    P=$!; echo "--- pilot flying"; break
+  fi
+done
+python3 "$SD/ob_by_hud.py" "${1:-240}" "${2:-25}"
+[ -n "${P:-}" ] && kill "$P" 2>/dev/null
+echo "OBHUD DONE"