diff --git a/inquiry-agent/agent/schema/sea_options.py b/inquiry-agent/agent/schema/sea_options.py
new file mode 100644
index 0000000..f121b3e
--- /dev/null
+++ b/inquiry-agent/agent/schema/sea_options.py
@@ -0,0 +1,64 @@
+"""
+海运运输分类：只认 Port to Port、其他。
+
+本文件职责：从原话收成标准词、生成补问清单。
+禁止：发明第三项；把分类带去 TMS；改六态。
+线程：纯函数，可在 Worker 槽调用。
+"""
+
+from __future__ import annotations
+
+SEA_CLASSES = ("Port to Port", "其他")
+
+# 长词优先，避免 P2P 误伤其它词；门到门不在名单里。
+_ALIASES = (
+    ("port to port", "Port to Port"),
+    ("港到港", "Port to Port"),
+    ("p2p", "Port to Port"),
+    ("其它", "其他"),
+    ("其他", "其他"),
+)
+
+
+def canonicalize_sea_class(raw: str) -> str:
+    """
+    把销售原话收成 Port to Port 或 其他；对不上返回空串。
+
+    「门到门」不算。先匹配更长别名。副作用：无。
+    """
+    text = (raw or "").strip()
+    if not text:
+        return ""
+    lowered = text.lower()
+    for needle, canon in _ALIASES:
+        if needle in lowered or needle in text:
+            return canon
+    stripped = text.replace("运输分类", "").replace("：", "").replace(":", "").strip()
+    if stripped in SEA_CLASSES:
+        return stripped
+    return ""
+
+
+def harvest_sea_class(text: str, current: dict[str, str] | None = None) -> dict[str, str]:
+    """
+    当前句能认则覆盖；认不出则保留已有标准值。
+
+    参数：本轮原文、已有 facts。返回合并后的 facts 副本。
+    非法旧值会丢掉，避免「门到门」一直占着必填位。
+    """
+    merged = dict(current or {})
+    found = canonicalize_sea_class(text or "")
+    if found:
+        merged["运输分类"] = found
+        return merged
+    kept = canonicalize_sea_class(str(merged.get("运输分类") or ""))
+    if kept:
+        merged["运输分类"] = kept
+    else:
+        merged.pop("运输分类", None)
+    return merged
+
+
+def sea_class_prompt() -> str:
+    """缺运输分类时只列两项，不再追问「其他是什么」。"""
+    return "运输分类（必填）：请回复 Port to Port 或 其他。"
diff --git a/inquiry-agent/tests/test_sea_options.py b/inquiry-agent/tests/test_sea_options.py
new file mode 100644
index 0000000..cb2abec
--- /dev/null
+++ b/inquiry-agent/tests/test_sea_options.py
@@ -0,0 +1,52 @@
+"""
+海运运输分类：只认 Port to Port、其他。
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+import unittest
+
+ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), ".."))
+if ROOT not in sys.path:
+    sys.path.insert(0, ROOT)
+
+from agent.schema.sea_options import (
+    canonicalize_sea_class,
+    harvest_sea_class,
+    sea_class_prompt,
+)
+
+
+class SeaOptionsTest(unittest.TestCase):
+    def test_port_to_port_aliases(self):
+        self.assertEqual(canonicalize_sea_class("Port to Port"), "Port to Port")
+        self.assertEqual(canonicalize_sea_class("port to port"), "Port to Port")
+        self.assertEqual(canonicalize_sea_class("P2P"), "Port to Port")
+        self.assertEqual(canonicalize_sea_class("港到港"), "Port to Port")
+
+    def test_other_alias(self):
+        self.assertEqual(canonicalize_sea_class("其他"), "其他")
+        self.assertEqual(canonicalize_sea_class("其它"), "其他")
+
+    def test_door_to_door_rejected(self):
+        self.assertEqual(canonicalize_sea_class("门到门"), "")
+
+    def test_harvest_keeps_current_when_text_has_none(self):
+        got = harvest_sea_class("上海到洛杉矶整柜", {"运输分类": "Port to Port"})
+        self.assertEqual(got["运输分类"], "Port to Port")
+
+    def test_harvest_overrides_from_text(self):
+        got = harvest_sea_class("运输分类：其他", {"运输分类": "Port to Port"})
+        self.assertEqual(got["运输分类"], "其他")
+
+    def test_prompt_lists_two_options_only(self):
+        text = sea_class_prompt()
+        self.assertIn("Port to Port", text)
+        self.assertIn("其他", text)
+        self.assertNotIn("门到门", text)
+
+
+if __name__ == "__main__":
+    unittest.main()