re: mission scripts are readable as dialogue (2683/2683 message calls resolve)

Built-in 64's slot-0 operand is a symbol-table-1 type-6 message id, and every
one of them now has caption text: 2683 of 2683 call sites across the 28 stage
scripts, 1338 distinct names, no residue of any kind.

This only became reachable once build_caption_text was switched to the IXUD
field table (537 -> 8800 lines); before that most of these names had nothing
to resolve to.

Adds isl_dialogue.py plus a committed Stage 02 sample. Does not settle which
recording plays for a given line, multi-page captions, or the other five
languages.

tools/re-capture/isl_dialogue.py

@@ -0,0 +1,142 @@
+#!/usr/bin/env python3
+"""Render a mission script's dialogue: every `request_script_message` in order,
+with the caption text it plays.
+
+    isl_dialogue.py <StageNN.ssb> [GP_MAIN_GAME_E.pak]
+
+Built-in 64 takes a symbol-table-1 (type 6) message name; the caption text lives
+in the pack's IXUD blocks under `<name>_<page>_<line>`. All 2683 call sites
+across the 28 stages resolve, so this is a total mapping rather than a sample.
+"""
+import collections
+import struct
+import sys
+
+import isl
+
+NO_NAME = 0xFFFFFFFF
+
+
+def be32(b, o):
+    return struct.unpack_from('>I', b, o)[0]
+
+
+def wstr(b, pool, off):
+    base = pool + 2 * off
+    e = base
+    while b[e:e + 2] != b'\0\0':
+        e += 2
+    return ''.join(chr(c) for c in struct.unpack('>%dH' % ((e - base) // 2), b[base:e]))
+
+
+def captions(pak_entries):
+    """`MSG_*` key -> text, read from the IXUD record/field table."""
+    out = {}
+    for b in pak_entries.values():
+        if b[:4] != b'IXUD':
+            continue
+        n = be32(b, 4)
+        o = 8 + 16 * n
+        m = be32(b, o)
+        o += 4
+        fields = [struct.unpack_from('>III', b, o + 12 * i) for i in range(m)]
+        o += 12 * m
+        pool = o + 4
+        for (_k, no, vo) in fields:
+            if no == NO_NAME:
+                continue
+            try:
+                key, val = wstr(b, pool, no), wstr(b, pool, vo)
+            except Exception:
+                continue
+            if key.startswith('MSG_') and val.strip():
+                out.setdefault(key, val)
+    return out
+
+
+def walk(b, base, nxt, sink):
+    staged, pending, off = {}, None, base
+    while off + 4 <= nxt:
+        w = be32(b, off)
+        op, ln = w & 0xFF, (w >> 8) & 0xFF
+        k1, k0 = (w >> 24) & 0xFF, (w >> 16) & 0xFF
+        if ln < 4 or ln % 4:
+            return
+        ws = [be32(b, off + i) for i in range(4, max(ln, 4), 4) if off + i + 4 <= len(b)]
+        if op in (0, 1) and len(ws) >= 2:
+            if k0 == 2 and k1 == 1:
+                pending = ws[1]
+            elif k0 == 3 and k1 == 2 and pending is not None:
+                staged[ws[0]] = pending
+            elif k0 == 3 and k1 == 1:
+                staged[ws[0]] = ws[1]
+        if op == 19 and ws:
+            sink(off, ws[0], dict(staged))
+            staged = {}
+        off += ln
+
+
+def main():
+    ssb = sys.argv[1]
+    pak = sys.argv[2] if len(sys.argv) > 2 else \
+        '/work/sylph_extract/dat/GP_MAIN_GAME_E.pak'
+    sys.path.insert(0, sys.path[0])
+    from unitgroup import read_entry  # noqa: F401  (kept for parity)
+    import zlib
+    import os
+
+    def pak_entries(path):
+        d = open(path, 'rb').read()
+        assert d[:4] == b'IPFB'
+        segs, base, i = b'', path[:-4], 0
+        while os.path.exists('%s.p%02d' % (base, i)):
+            segs += open('%s.p%02d' % (base, i), 'rb').read()
+            i += 1
+        out = {}
+        for k in range(be32(d, 4)):
+            h, off, cs = struct.unpack_from('>III', d, 0x10 + 12 * k)
+            raw = segs[off:off + cs]
+            if raw[:2] == b'Z1':
+                raw = zlib.decompress(raw[10:])
+            out[h] = raw
+        return out
+
+    cap = captions(pak_entries(pak))
+    b = isl.load(ssb)
+    s1 = isl.symbols(b, 1)
+    end = be32(b, 0x0C)
+    lines = []
+
+    def sink(off, bid, st):
+        if bid != 64:
+            return
+        v = st.get(0)
+        if not isinstance(v, int) or v not in s1:
+            return
+        name = s1[v][1]
+        text = [cap[k] for k in
+                ('%s_000_%02d' % (name, i) for i in range(4)) if k in cap]
+        lines.append((off, name, ' '.join(text)))
+
+    bases = isl.phase_bases(b) + [end]
+    for i in range(len(bases) - 1):
+        walk(b, bases[i], bases[i + 1], sink)
+
+    name = ssb.replace('\\', '/').split('/')[-1]
+    print('# %s — dialogue, in script order' % name)
+    print()
+    print('Generated by `tools/re-capture/isl_dialogue.py`. Each line is one')
+    print('`request_script_message` (built-in 64) and the caption it plays.')
+    print()
+    print('%d message calls, %d with text.' % (len(lines), sum(1 for _, _, t in lines if t)))
+    print()
+    seen = set()
+    for off, nm, text in lines:
+        if off in seen:
+            continue
+        seen.add(off)
+        print('%06X  %-22s %s' % (off, nm, text))
+
+
+if __name__ == '__main__':
+    main()