Add scratchpad/cursoraudit.py: static audit for the #42 stale-cursor draw family

Scans the gauge TUs for cursor-relative draws with no MoveToAbsolute in scope.
Found 6 of 29, three of them STATE-CHANGE-ONLY draws -- notably
L4GraphicLamp::NotifyOfStateChange (L4LAMP.cpp:376/380), which blits a lamp using
whatever cursor the view happens to hold.  That is the '#48 misplaced lamp'
class: lamp-shaped, on the panels that have lamps, only on damage/jam/heat state
changes, and persistent.  Explains why the 5-pilot rig capture was clean (no
combat = no lamp state change).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0166KTsC7ADm7VXEi1HF1jNg

scratchpad/cursoraudit.py

@@ -0,0 +1,75 @@
+"""#48 audit: find gauge draws that are NOT preceded by a cursor set.
+
+The #42 family: a draw that relies on the CURRENT cursor works by accident the
+first time (the cursor happens to be right) and lands in the wrong place on a
+later redraw.  Draws that only fire on a STATE CHANGE -- damage, heat, jam,
+alarm -- are the dangerous ones: they are rare, so the bug hides until gameplay
+triggers them, and nothing erases the stray pixels afterwards.
+
+Relative/cursor-relative draws (the risky ones) vs absolute draws (safe):
+  RISKY : DrawFilledRectangleToRelative, DrawBitMap*, DrawLineToRelative,
+          DrawPointToRelative, DrawFilledRectangleToAbsolute (uses cursor as one corner)
+  SAFE  : anything taking explicit x,y (DrawPortBackground, NumericDisplay::Draw
+          which carries its own coords)
+
+Reports each risky draw with the distance back to the nearest MoveToAbsolute /
+MoveToRelative in the same function, and flags any that has none.
+"""
+import os
+import re
+
+FILES = [
+    "game/reconstructed/btl4gau2.cpp",   # weapon panels + eng pages (artifacts seen here)
+    "game/reconstructed/btl4gau3.cpp",   # pilotList, PlayerStatus, MessageBoard
+    "game/reconstructed/btl4gau1.cpp",
+    "game/reconstructed/btl4grnd.cpp",
+    "engine/MUNGA_L4/L4GAUGE.cpp",
+    "engine/MUNGA_L4/L4LAMP.cpp",
+]
+
+RISKY = re.compile(r"\.(DrawFilledRectangleToRelative|DrawBitMapOpaque|DrawBitMap|"
+                   r"DrawLineToRelative|DrawPointToRelative|"
+                   r"DrawFilledRectangleToAbsolute)\s*\(")
+CURSOR = re.compile(r"\.(MoveToAbsolute|MoveToRelative)\s*\(")
+FUNCHEAD = re.compile(r"^(?:\t|)([A-Za-z_][A-Za-z0-9_]*::[A-Za-z_][A-Za-z0-9_]*)\s*\(")
+
+root = r"C:\git\bt411"
+findings = []
+for rel in FILES:
+    path = os.path.join(root, rel.replace("/", os.sep))
+    if not os.path.exists(path):
+        continue
+    lines = open(path, encoding="utf-8", errors="replace").read().splitlines()
+    func = "?"
+    func_start = 0
+    last_cursor = -1
+    for i, ln in enumerate(lines):
+        m = FUNCHEAD.match(ln)
+        if m:
+            func = m.group(1)
+            func_start = i
+            last_cursor = -1          # cursor state does not carry across functions
+        if CURSOR.search(ln):
+            last_cursor = i
+        mm = RISKY.search(ln)
+        if mm:
+            gap = (i - last_cursor) if last_cursor >= func_start else None
+            findings.append((rel, i + 1, func, mm.group(1), gap, ln.strip()[:78]))
+
+print("=" * 100)
+print("RISKY DRAWS WITH **NO** CURSOR SET IN THE ENCLOSING FUNCTION  (top suspects)")
+print("=" * 100)
+none = [f for f in findings if f[4] is None]
+for rel, line, func, call, gap, src in none:
+    print("  %-32s :%-5d %-42s %s" % (rel.split("/")[-1], line, func, call))
+    print("        %s" % src)
+print("\n  -> %d of %d risky draws have NO cursor set in scope\n" % (len(none), len(findings)))
+
+print("=" * 100)
+print("RISKY DRAWS WHOSE CURSOR SET IS FAR AWAY (>12 lines -- may be on another branch)")
+print("=" * 100)
+far = [f for f in findings if f[4] is not None and f[4] > 12]
+for rel, line, func, call, gap, src in far:
+    print("  %-32s :%-5d gap=%-4d %-38s %s" % (rel.split("/")[-1], line, gap, func, call))
+print("\n  -> %d far-cursor draws" % len(far))
+print("\ntotal risky draws scanned: %d" % len(findings))