diff --git a/app/platform/registry.py b/app/platform/registry.py
index 7d6663d..837cc68 100644
--- a/app/platform/registry.py
+++ b/app/platform/registry.py
@@ -29,6 +29,7 @@ FileTenantSource(seed_profiles/,测试/出厂档案)与 DbTenantSource
 """
 import asyncio
 import pathlib
+import re
 from dataclasses import dataclass
 
 from sqlalchemy import event
@@ -49,6 +50,10 @@ from app.platform.tenant_source import (
     TenantSource,
 )
 
+# 租户 slug 形态(创建侧 tenant_routes 原 SLUG_RE 的单一事实源——路径前缀
+# 解析与创建校验共用,永不漂移;spec 2026-10-19 §3.1)
+TENANT_SLUG_RE = re.compile(r"^[a-z0-9-]+$")
+
 
 class UnknownTenantError(LookupError):
     """Host/域名无法映射到任何租户(调用方语义:聊天/公开端点 404)。"""
@@ -225,6 +230,23 @@ class TenantRegistry:
         """resolve_site 的便捷形式(双 API 一层实现)。"""
         return (await self.resolve_site(host))[0]
 
+    async def resolve_by_slug(self, slug: str) -> tuple[TenantRuntime, Site]:
+        """路径前缀模式(/t/<slug>/,spec 2026-10-19 §5):slug → (runtime,
+        首站点)。语义与 resolve_site 同款:未知 slug / 空站点表 →
+        UnknownTenantError;停用 → TenantDisabledError;懒建 engine、
+        reload 竞态取 _ensure_ready 返回值(与 resolve_site 同理)。"""
+        rt = self._by_slug.get(slug)
+        if rt is None:
+            raise UnknownTenantError(f"未知租户 slug: {slug!r}")
+        if rt.config.status != "active":
+            raise TenantDisabledError(f"租户已停用: {slug!r}")
+        rt = await self._ensure_ready(rt)
+        if not rt.config.sites:
+            # 创建向导恒建 main 站点,此分支为防御(spec §5)
+            raise UnknownTenantError(
+                f"租户 {slug!r} 无站点——路径模式无从选站点")
+        return rt, rt.config.sites[0]
+
     # ---- 装配期辅助(Task 5b: main.lifespan 逐租户启动清扫)------------------
 
     def runtimes(self) -> tuple[TenantRuntime, ...]:
diff --git a/tests/test_registry.py b/tests/test_registry.py
index 1654f4e..e68b1be 100644
--- a/tests/test_registry.py
+++ b/tests/test_registry.py
@@ -9,6 +9,7 @@ Windows 纪律:每个建过 engine 的用例结尾 await reg.dispose_all()——
 连接不关,文件锁着,tmp_path 清理 PermissionError。
 """
 import asyncio
+import dataclasses
 import json
 import shutil
 from pathlib import Path
@@ -22,6 +23,7 @@ from app.platform.registry import (
     UnknownTenantError,
     make_tenant_engine,
 )
+from app.platform.tenant_source import FileTenantSource
 
 REPO_ROOT = Path(__file__).resolve().parents[1]
 SEED_DIR = REPO_ROOT / "seed_profiles"
@@ -296,3 +298,45 @@ async def test_reload_to_disabled_releases_engine(tmp_path):
     with pytest.raises(TenantDisabledError):
         await reg.resolve("a.example.com")
     await reg.dispose_all()
+
+
+# ---- 路径前缀模式解析(spec 2026-10-19 §5) ----------------------------------
+
+
+class TestResolveBySlug:
+    """resolve_by_slug:/t/<slug>/ 路径模式的 slug 直查——语义与 resolve_site
+    同款(未知/停用/懒建/reload 竞态取 _ensure_ready 返回值),首站点为默认。"""
+
+    async def test_已知_slug_返回租户与首站点(self, tmp_path):
+        reg = TenantRegistry.load_from_dir(SEED_DIR, data_dir=tmp_path)
+        rt, site = await reg.resolve_by_slug("jiancai")
+        assert rt.config.slug == "jiancai"
+        assert site.slug == rt.config.sites[0].slug  # 首站点为默认
+        await reg.dispose_all()
+
+    async def test_未知_slug_UnknownTenantError(self, tmp_path):
+        reg = TenantRegistry.load_from_dir(SEED_DIR, data_dir=tmp_path)
+        with pytest.raises(UnknownTenantError):
+            await reg.resolve_by_slug("no-such")
+        await reg.dispose_all()
+
+    async def test_停用租户_TenantDisabledError(self, tmp_path):
+        seed = _write_seed(
+            tmp_path, {"jiancai": _tenant("jiancai", status="disabled")})
+        reg = TenantRegistry.load_from_dir(seed, data_dir=tmp_path / "data")
+        with pytest.raises(TenantDisabledError):
+            await reg.resolve_by_slug("jiancai")
+        await reg.dispose_all()
+
+    async def test_空站点表按未知处理(self, tmp_path):
+        """防御分支(spec §5):两源加载期均拒零站点,直装 sites=[] 的
+        LoadedTenant 绕过源校验覆盖该分支——正常运行不可达,防将来源
+        语义漂移。"""
+        seed = _write_seed(tmp_path, {"jiancai": _tenant("jiancai")})
+        source = FileTenantSource(seed)
+        lt = dataclasses.replace(source.read_tenant("jiancai"), sites=[])
+        reg = TenantRegistry(source, data_dir=tmp_path / "data")
+        reg._install([lt])                        # 手工装配(单元测试:直装内部)
+        with pytest.raises(UnknownTenantError):
+            await reg.resolve_by_slug("jiancai")
+        await reg.dispose_all()