diff --git a/README.md b/README.md
index 5b1bed2..a58aed7 100644
--- a/README.md
+++ b/README.md
@@ -50,3 +50,18 @@
 - [x] **P4** 区块解析（`mcfold/chunk.py`，11 项回归全绿）
       位打包 / 单值·本地·全局调色板 / 生物群系 section / 世界边界
       **关键行为**：越界 state id ⇒ `unknown(id)`（对照 mineflayer 的静默错配）
+- [x] **P5** mod jar 解析（`mcfold/modjar.py`，8 项回归全绿）
+      三种加载器真实样本验证（Forge / NeoForge / Fabric）+ 多加载器 jar 诊断
+      可提取：mod id / 名称 / 版本 / **方块名清单** / 物品名清单
+      **诚实边界**：拿不到 state id（已在摘要里明说，见附录 D）
+
+## 累计测试
+
+| 套件 | 项数 |
+|---|---|
+| 版本解析 | 6 |
+| protodef | 6 |
+| 区块解析 | 11 |
+| mod jar | 8 |
+| 跨实现互操作 | 2 |
+| **合计** | **33** |
diff --git a/mcfold/__pycache__/modjar.cpython-312.pyc b/mcfold/__pycache__/modjar.cpython-312.pyc
new file mode 100644
index 0000000..4a6cf56
Binary files /dev/null and b/mcfold/__pycache__/modjar.cpython-312.pyc differ
diff --git a/mcfold/modjar.py b/mcfold/modjar.py
new file mode 100644
index 0000000..ad984e6
--- /dev/null
+++ b/mcfold/modjar.py
@@ -0,0 +1,224 @@
+"""mod jar 解析：从 jar 里读出加载器元数据与**方块名清单**。
+
+实测边界（2026-09-25，文档附录 D/E）——必须说清的：
+    ✅ 能拿到：mod id / 名称 / 版本 / 加载器 / 方块名清单 / 物品名清单
+    ❌ 拿不到：**state id 映射**
+
+为什么拿不到 state id：state id 是服务端加载 mod 时**动态分配**的，
+jar 里不存在；而 1.20.1 又不在网络上传方块注册表（见附录 D）。
+1.20.2+ 会在 configuration 阶段发 registry_data，那条路另议。
+
+所以本模块的定位是：
+  1. 让 agent 知道「本实例装了什么、有哪些方块名」
+  2. 用方块名做**指令校验**（避免让 agent 去操作一个这服没有的方块）
+  3. 配合 world 模块把「本机注册表没有的 state id」报告为 unknown 并归因到 mod
+"""
+
+from __future__ import annotations
+
+import json
+import re
+import zipfile
+from dataclasses import dataclass, field
+from pathlib import Path
+from typing import Any
+
+# 加载器元数据文件 → 加载器类型 / 解析方式
+META_FILES: tuple[tuple[str, str, str], ...] = (
+    ("META-INF/neoforge.mods.toml", "neoforge", "toml"),
+    ("META-INF/mods.toml", "forge", "toml"),
+    ("fabric.mod.json", "fabric", "json"),
+    ("quilt.mod.json", "quilt", "json"),
+)
+
+
+@dataclass
+class ModInfo:
+    """一个 mod jar 的解析结果。"""
+    path: Path
+    loader: str                       # forge / neoforge / fabric / quilt / unknown
+    mod_id: str = ""
+    name: str = ""
+    version: str = ""
+    # 方块名（不含命名空间前缀），来自 assets/<ns>/blockstates/*.json
+    block_names: list[str] = field(default_factory=list)
+    item_names: list[str] = field(default_factory=list)
+    namespaces: list[str] = field(default_factory=list)
+    depends: dict[str, str] = field(default_factory=dict)
+    loaders_present: list[str] = field(default_factory=list)   # 多加载器 jar 时列出全部
+    error: str | None = None
+
+    @property
+    def ok(self) -> bool:
+        return self.error is None
+
+    def qualified_blocks(self) -> list[str]:
+        """带命名空间的方块名，形如 expandeddelight:cask。"""
+        ns = self.mod_id or (self.namespaces[0] if self.namespaces else "")
+        return [f"{ns}:{n}" for n in self.block_names] if ns else list(self.block_names)
+
+
+# ---------------- 元数据解析 ----------------
+
+def _parse_toml(text: str) -> dict[str, Any]:
+    """极简 TOML 读取：只取 mods.toml 用到的形式（够了，不引入依赖）。
+
+    支持：key = "value"、[[mods]] 分段；其余分段（如 [dependencies.*]）忽略。
+
+    踩过的坑（实测）：判断 [[mods]] 不能用 `line.rstrip("]")` ——
+    "[[mods]]".rstrip("]") 得到 "[[mods"，并不以 "mods" 结尾，条件永远为假。
+    """
+    out: dict[str, Any] = {"mods": []}
+    cur: dict[str, Any] | None = None
+    for raw in text.splitlines():
+        line = raw.strip()
+        if not line or line.startswith("#"):
+            continue
+        # 数组表头 [[mods]]（可能带行内注释："[[mods]] #mandatory"）
+        if line.startswith("[["):
+            mh = re.match(r"^\[\[([^\]]+)\]\]", line)
+            header = mh.group(1).strip() if mh else ""
+            cur = {} if header == "mods" else None
+            if cur is not None:
+                out["mods"].append(cur)
+            continue
+        if line.startswith("["):
+            cur = None            # 进入其它分段，忽略
+            continue
+        m = re.match(r'^([A-Za-z_][\w]*)\s*=\s*(.+?)\s*$', line)
+        if not m:
+            continue
+        key, val = m.group(1), m.group(2)
+        val = re.sub(r"\s*#.*$", "", val).strip().rstrip(",")
+        if val.startswith('"') and val.endswith('"'):
+            val = val[1:-1]
+        elif val.startswith("'") and val.endswith("'"):
+            val = val[1:-1]
+        if cur is not None:
+            cur.setdefault(key, val)   # 取首个（后续多为依赖声明重名）
+        else:
+            out.setdefault(key, val)
+    return out
+
+
+def detect_loaders(zf: zipfile.ZipFile) -> list[str]:
+    """列出 jar 里出现的**全部**加载器元数据类型（多加载器 jar 诊断用）。"""
+    names = set(zf.namelist())
+    return [loader for fname, loader, _ in META_FILES if fname in names]
+
+
+def _read_meta(zf: zipfile.ZipFile) -> tuple[str, dict[str, Any], str]:
+    """从 jar 读出加载器元数据。返回 (loader, meta, kind)。
+
+    注意：很多 mod 是**多加载器 jar**（实测 Explorify 同时含 mods.toml、
+    neoforge.mods.toml、fabric.mod.json）。此时按 META_FILES 的优先级取第一个，
+    但要记录全部候选，便于诊断。
+    """
+    names = set(zf.namelist())
+    for fname, loader, kind in META_FILES:
+        if fname in names:
+            raw = zf.read(fname).decode("utf-8", errors="replace")
+            meta = json.loads(raw) if kind == "json" else _parse_toml(raw)
+            return loader, meta, kind
+    return "unknown", {}, "none"
+
+
+def _extract_identity(loader: str, meta: dict[str, Any]) -> tuple[str, str, str, dict[str, str]]:
+    """取 (mod_id, name, version, depends)。"""
+    if loader in ("forge", "neoforge"):
+        mods = meta.get("mods") or [{}]
+        first = mods[0] if mods else {}
+        mid = first.get("modId") or first.get("modid") or ""
+        return mid, first.get("displayName", "") or mid, first.get("version", ""), {}
+    # fabric / quilt
+    mid = meta.get("id", "")
+    depends = {}
+    for k, v in (meta.get("depends") or {}).items():
+        depends[k] = ", ".join(v) if isinstance(v, list) else str(v)
+    return mid, meta.get("name", "") or mid, str(meta.get("version", "")), depends
+
+
+def _scan_names(zf: zipfile.ZipFile) -> tuple[list[str], list[str], list[str]]:
+    """扫 jar 里的资源目录，得到方块名 / 物品名 / 命名空间。
+
+    权威依据（实测）：方块名在 assets/<ns>/blockstates/<name>.json，
+    物品名在 assets/<ns>/models/item/<name>.json。
+    """
+    blocks: set[str] = set()
+    items: set[str] = set()
+    namespaces: set[str] = set()
+
+    for n in zf.namelist():
+        m = re.match(r"^assets/([^/]+)/blockstates/(.+)\.json$", n)
+        if m:
+            namespaces.add(m.group(1))
+            blocks.add(m.group(2))
+            continue
+        m = re.match(r"^assets/([^/]+)/models/item/(.+)\.json$", n)
+        if m:
+            namespaces.add(m.group(1))
+            items.add(m.group(2))
+
+    return sorted(blocks), sorted(items), sorted(namespaces)
+
+
+def parse_mod(path: str | Path) -> ModInfo:
+    """解析单个 mod jar。失败不抛异常，而是把原因记在 error 里。"""
+    p = Path(path)
+    info = ModInfo(path=p, loader="unknown")
+    try:
+        with zipfile.ZipFile(p) as zf:
+            info.loaders_present = detect_loaders(zf)
+            loader, meta, _kind = _read_meta(zf)
+            info.loader = loader
+            if loader != "unknown":
+                mid, name, ver, depends = _extract_identity(loader, meta)
+                info.mod_id, info.name, info.version, info.depends = mid, name, ver, depends
+            blocks, items, ns = _scan_names(zf)
+            info.block_names, info.item_names, info.namespaces = blocks, items, ns
+            if not info.mod_id and ns:
+                info.mod_id = ns[0]
+    except zipfile.BadZipFile:
+        info.error = "不是有效的 zip/jar"
+    except Exception as e:                     # noqa: BLE001 - 解析失败不应中断整目录扫描
+        info.error = f"{type(e).__name__}: {e}"
+    return info
+
+
+def scan_mods(mods_dir: str | Path) -> list[ModInfo]:
+    """扫描实例的 mods/ 目录。跳过 .disabled 与目录。"""
+    d = Path(mods_dir)
+    if not d.is_dir():
+        return []
+    out: list[ModInfo] = []
+    for f in sorted(d.iterdir()):
+        if f.is_dir() or f.name.startswith("."):
+            continue
+        if f.suffix.lower() not in (".jar", ".zip"):
+            continue
+        out.append(parse_mod(f))
+    return out
+
+
+def summarize(mods: list[ModInfo]) -> dict[str, Any]:
+    """给 agent 看的摘要（用于 mod 感知的降级提示）。"""
+    ok = [m for m in mods if m.ok]
+    bad = [m for m in mods if not m.ok]
+    blocks: list[str] = []
+    for m in ok:
+        blocks.extend(m.qualified_blocks())
+    return {
+        "count": len(mods),
+        "loaded": len(ok),
+        "failed": len(bad),
+        "mods": [
+            {"id": m.mod_id, "name": m.name, "version": m.version,
+             "loader": m.loader, "blocks": len(m.block_names)}
+            for m in ok
+        ],
+        "failed_detail": [{"file": m.path.name, "error": m.error} for m in bad],
+        "block_names": sorted(set(blocks)),
+        "block_name_count": len(set(blocks)),
+        # 诚实标注：这是**方块名**，不是 state id
+        "note": "mod 方块名清单（state id 无法从 jar 获得，见文档附录 D）",
+    }
diff --git a/tests/test_modjar.py b/tests/test_modjar.py
new file mode 100644
index 0000000..ca7e96d
--- /dev/null
+++ b/tests/test_modjar.py
@@ -0,0 +1,126 @@
+"""mod jar 解析回归 —— 用**真实 mod jar** 验证（三种加载器 + 边界）。"""
+import sys, os, json, zipfile, io, tempfile
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+from mcfold.modjar import parse_mod, scan_mods, summarize, _parse_toml, detect_loaders
+
+FORGE   = "/home/mc-test/mods/curtain-mc1.20.1-1.3.2.jar"
+NEOFORGE= "/home/minecraft/mods/bettercombat-neoforge-2.3.2+1.21.1.jar"
+MULTI   = "/home/minecraft/mods/Explorify v1.6.4 f15-88.mod.jar"
+BLOCKS  = "/home/minecraft/mods/[扩充乐事] expandeddelight-0.1.4.jar"
+
+def exists(p): return os.path.isfile(p)
+
+def test_toml_parser_comment_headers():
+    """★ 踩过的坑：表头带行内注释（'[[mods]] #mandatory'）必须正确识别。"""
+    text = '''
+loaderVersion = "[47,)"
+[[mods]] #mandatory
+modId = "curtain" #mandatory
+version = "${file.jarVersion}"
+displayName = "Curtain"
+[[dependencies.curtain]]
+modId = "forge"
+'''
+    m = _parse_toml(text)
+    assert len(m["mods"]) == 1, f"mods 段数应为 1，实际 {len(m['mods'])}"
+    assert m["mods"][0]["modId"] == "curtain", m["mods"][0]
+    assert m["mods"][0]["displayName"] == "Curtain"
+    # 依赖段的 modId 不应污染 mods[0]
+    assert m["mods"][0]["modId"] != "forge"
+    print("  ✓ TOML: 带行内注释的 [[mods]] 正确识别，依赖段不污染")
+
+def test_forge_real():
+    if not exists(FORGE):
+        print("  - forge 样本不存在，跳过"); return
+    m = parse_mod(FORGE)
+    assert m.loader == "forge", m.loader
+    assert m.mod_id == "curtain", m.mod_id
+    assert m.name == "Curtain", m.name
+    # curtain 只加命令、不新增方块 —— 0 方块是正确结果
+    assert m.block_names == [], m.block_names
+    print(f"  ✓ Forge 真实: id={m.mod_id} name={m.name} 方块=0（它只加命令）")
+
+def test_neoforge_real():
+    if not exists(NEOFORGE):
+        print("  - neoforge 样本不存在，跳过"); return
+    m = parse_mod(NEOFORGE)
+    assert m.loader == "neoforge", m.loader
+    assert m.mod_id == "bettercombat", m.mod_id
+    assert m.version == "2.3.2+1.21.1", m.version
+    print(f"  ✓ NeoForge 真实: id={m.mod_id} ver={m.version}")
+
+def test_multi_loader_jar():
+    """多加载器 jar（同时含 forge/neoforge/fabric 元数据）必须能诊断。"""
+    if not exists(MULTI):
+        print("  - 多加载器样本不存在，跳过"); return
+    m = parse_mod(MULTI)
+    assert len(m.loaders_present) >= 2, m.loaders_present
+    assert m.mod_id == "explorify", m.mod_id
+    # 结构 mod：用原版方块生成地形，自己不新增方块 ⇒ 0 方块正确
+    assert m.block_names == [], m.block_names
+    print(f"  ✓ 多加载器 jar: 含 {m.loaders_present}，id={m.mod_id}（结构 mod，0 方块）")
+
+def test_block_extraction_real():
+    """★ 核心：从真实 mod 提取方块名清单（这是 mod 支持的可见部分）。"""
+    if not exists(BLOCKS):
+        print("  - 方块 mod 样本不存在，跳过"); return
+    m = parse_mod(BLOCKS)
+    assert m.mod_id == "expandeddelight", m.mod_id
+    assert len(m.block_names) > 20, f"方块数偏少: {len(m.block_names)}"
+    # 已知方块（前面实测过）
+    for want in ("cask", "cheese_wheel", "asparagus_crate"):
+        assert want in m.block_names, f"缺方块 {want}"
+    q = m.qualified_blocks()
+    assert "expandeddelight:cask" in q, q[:5]
+    # 物品也应提取到
+    assert len(m.item_names) > 20, len(m.item_names)
+    print(f"  ✓ 方块提取: {len(m.block_names)} 方块 / {len(m.item_names)} 物品，含 cask/cheese_wheel")
+
+def test_no_state_id_claim():
+    """★ 诚实性：解析结果里**不含** state id（因为拿不到），摘要必须明说。"""
+    m = parse_mod(BLOCKS) if exists(BLOCKS) else None
+    if m is None:
+        print("  - 跳过"); return
+    s = summarize([m])
+    assert "state id" in s["note"], s["note"]
+    assert "block_names" in s and s["block_name_count"] > 0
+    # 摘要里不应有任何形如 state id 的映射承诺
+    assert "state_ids" not in s and "stateId" not in json.dumps(s)
+    print(f"  ✓ 诚实标注: 摘要含 {s['block_name_count']} 方块名，并注明无 state id")
+
+def test_bad_jar_no_crash():
+    """损坏的 jar 不能中断整目录扫描。"""
+    with tempfile.TemporaryDirectory() as d:
+        p = os.path.join(d, "broken.jar")
+        open(p, "wb").write(b"this is not a zip")
+        m = parse_mod(p)
+        assert not m.ok and "zip" in (m.error or "").lower(), m.error
+        good = os.path.join(d, "ok.jar")
+        with zipfile.ZipFile(good, "w") as zf:
+            zf.writestr("fabric.mod.json", json.dumps({"id":"t","name":"T","version":"1"}))
+        mods = scan_mods(d)
+        assert len(mods) == 2, len(mods)
+        s = summarize(mods)
+        assert s["loaded"] == 1 and s["failed"] == 1, s
+        print(f"  ✓ 损坏 jar 不中断扫描: loaded={s['loaded']} failed={s['failed']}")
+
+def test_json_meta_without_assets():
+    """纯 JSON 元数据、无 assets 的 mod 也要能拿到 id（边界）。"""
+    with tempfile.TemporaryDirectory() as d:
+        p = os.path.join(d, "t.jar")
+        with zipfile.ZipFile(p, "w") as zf:
+            zf.writestr("fabric.mod.json", json.dumps(
+                {"id":"mymod","name":"My Mod","version":"2.0",
+                 "depends":{"minecraft":">=1.20","fabric-api":"*"}}))
+        m = parse_mod(p)
+        assert m.loader == "fabric" and m.mod_id == "mymod", (m.loader, m.mod_id)
+        assert m.depends.get("minecraft") == ">=1.20", m.depends
+        assert m.block_names == []
+        print("  ✓ fabric 纯元数据: id/depends 正确，无 assets 不报错")
+
+if __name__ == "__main__":
+    for fn in [test_toml_parser_comment_headers, test_forge_real, test_neoforge_real,
+               test_multi_loader_jar, test_block_extraction_real, test_no_state_id_claim,
+               test_bad_jar_no_crash, test_json_meta_without_assets]:
+        fn()
+    print("\nmod jar 解析：全部通过")