chore: initialize age-reimpl repo

Reverse-engineering + open reimplementation workspace for Eushully's AGE/SYS4
engine (first target: Himegari). The repo root is age-reimpl/; the original game
install and the extracted ALF data are siblings outside the repo and are never
tracked. build/ (derived corpora) is gitignored and regenerated by the tools.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tools/extract_phase2.py

@@ -0,0 +1,112 @@
+#!/usr/bin/env python3
+"""Phase 2 batch extraction: disassembly + text corpora from every SYS4 script.
+
+Outputs (all under build/, workspace-root relative):
+  build/disasm/<NAME>.asm         full disassembly listing (one per script)
+  build/text/<NAME>.strings.txt   all inline strings in that script
+  build/text/dialogue.jsonl       show-text (0x6E) lines only — the translation corpus
+  build/text/strings.jsonl        every inline string, tagged by the opcode that references it
+  build/manifest.json             per-script stats (instructions, strings, dialogue, decode-clean)
+
+Authoritative copies: a game-dir override shadows its extracted/DATA1 copy. Run:
+  py -3.11 -X utf8 tools/extract_phase2.py
+"""
+from __future__ import annotations
+import json
+import os
+import sys
+from pathlib import Path
+
+HERE = Path(__file__).resolve().parent
+sys.path.insert(0, str(HERE))
+import paths
+import sys4load
+
+DATA1 = paths.DATA1
+BUILD = paths.BUILD
+DISASM = BUILD / "disasm"
+TEXT = BUILD / "text"
+
+SHOW_TEXT = 0x6E                        # dialogue opcode; type-2 arg = displayed line
+
+
+def authoritative_scripts() -> dict[str, Path]:
+    """name -> path, game-dir overrides winning over extracted/DATA1."""
+    return paths.scripts()
+
+
+def opcode_for_string_ref(scr, value_dword_index: int) -> tuple[int | None, str | None]:
+    """Given the body index of a string's *value* operand, find the owning instruction."""
+    for ins in scr.instructions:
+        base = ins.offset + 1
+        for a in range(len(ins.args)):
+            if base + 2 * a + 1 == value_dword_index:
+                return ins.opcode, ins.label
+    return None, None
+
+
+def main() -> int:
+    for d in (DISASM, TEXT, BUILD / "data", BUILD / "scripts-json"):
+        d.mkdir(parents=True, exist_ok=True)
+
+    files = authoritative_scripts()
+    manifest = []
+    n_dialogue = n_strings = 0
+    skipped = []
+
+    with (TEXT / "dialogue.jsonl").open("w", encoding="utf-8") as dlg, \
+         (TEXT / "strings.jsonl").open("w", encoding="utf-8") as allstr:
+        for name, p in sorted(files.items()):
+            try:
+                scr = sys4load.load(p)
+            except sys4load.Sys4Error as e:
+                skipped.append((name, str(e)))
+                continue
+
+            # 1) disassembly listing
+            (DISASM / f"{Path(name).stem}.asm").write_text(
+                sys4load.render_listing(scr), encoding="utf-8")
+
+            # 2) per-script strings file
+            if scr.strings:
+                lines = [f"0x{off:05x}\t{txt}" for off, (txt, _) in sorted(scr.strings.items())]
+                (TEXT / f"{Path(name).stem}.strings.txt").write_text(
+                    "\n".join(lines) + "\n", encoding="utf-8")
+
+            # 3) combined corpora, tagged by referencing opcode
+            for val_idx, off in sorted(scr.string_refs.items(), key=lambda kv: kv[1]):
+                txt = scr.strings.get(off, (None,))[0]
+                if txt is None:
+                    continue
+                op, label = opcode_for_string_ref(scr, val_idx)
+                rec = {"file": name, "off": f"0x{off:x}",
+                       "op": f"0x{op:x}" if op is not None else None,
+                       "label": label, "text": txt}
+                allstr.write(json.dumps(rec, ensure_ascii=False) + "\n")
+                n_strings += 1
+                if op == SHOW_TEXT:
+                    dlg.write(json.dumps({"file": name, "off": f"0x{off:x}", "text": txt},
+                                         ensure_ascii=False) + "\n")
+                    n_dialogue += 1
+
+            n, unk, trunc, clean = sys4load.decode_stats(scr)
+            manifest.append({"file": name, "instructions": n, "strings": len(scr.strings),
+                             "clean": clean, "unknown": unk, "truncated": trunc})
+
+    (BUILD / "manifest.json").write_text(
+        json.dumps({"scripts": len(manifest), "skipped": skipped,
+                    "total_dialogue_lines": n_dialogue, "total_strings": n_strings,
+                    "per_script": manifest}, ensure_ascii=False, indent=2), encoding="utf-8")
+
+    clean = sum(1 for m in manifest if m["clean"])
+    print(f"scripts processed: {len(manifest)}  (decode-clean: {clean}/{len(manifest)})")
+    print(f"skipped (non-script magic): {len(skipped)}  -> {[s[0] for s in skipped]}")
+    print(f"disasm listings: build/disasm/*.asm")
+    print(f"dialogue lines (show-text): {n_dialogue}  -> build/text/dialogue.jsonl")
+    print(f"all inline strings: {n_strings}  -> build/text/strings.jsonl")
+    print(f"manifest: build/manifest.json")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())