diff --git a/backend/AGENTS.md b/backend/AGENTS.md
index 20f63e0a4..95b9a1cda 100644
--- a/backend/AGENTS.md
+++ b/backend/AGENTS.md
@@ -347,8 +347,8 @@ Proxied through nginx: `/api/langgraph/*` → Gateway LangGraph-compatible runti
 **Provider Pattern**: `SandboxProvider` with `acquire`, `acquire_async`, `get`, `release` lifecycle. Async agent/tool paths call async sandbox lifecycle hooks so Docker sandbox creation, discovery, cross-process locking, readiness polling, and release stay off the event loop.
 **Environment policy** (`sandbox/env_policy.py`): `execute_command` no longer inherits the full `os.environ`. `build_sandbox_env()` scrubs secret-looking names (`*KEY*`/`*SECRET*`/`*TOKEN*`/`*PASSWORD*`/`*CREDENTIAL*`) from the inherited environment before layering injected request secrets on top, so platform credentials (e.g. `OPENAI_API_KEY`) never leak into skill subprocesses. Benign vars (`PATH`, `HOME`, `LANG`, `VIRTUAL_ENV`, ...) are preserved.
 **Implementations**:
-- `LocalSandboxProvider` - Local filesystem execution. `acquire(thread_id)` returns a per-thread `LocalSandbox` (id `local:{thread_id}`) whose `path_mappings` resolve `/mnt/user-data/{workspace,uploads,outputs}` and `/mnt/acp-workspace` to that thread's host directories, so the public `Sandbox` API honours the `/mnt/user-data` contract uniformly with AIO. `acquire()` / `acquire(None)` keeps the legacy generic singleton (id `local`) for callers without a thread context. Per-thread sandboxes are held in an LRU cache (default 256 entries) guarded by a `threading.Lock`.
-- `AioSandboxProvider` (`packages/harness/deerflow/community/`) - Docker-based isolation. Active-cache and warm-pool entries are checked with the backend during acquire/reuse; definitively dead containers are dropped from all in-process maps so the thread can discover or create a fresh sandbox instead of reusing a stale client. Backend health-check failures are treated as unknown, not dead; local discovery likewise treats an unverifiable container as not adoptable and falls through to create rather than failing acquire. `get()` remains an in-memory lookup for event-loop-safe tool paths.
+- `LocalSandboxProvider` - Local filesystem execution. `acquire(thread_id)` returns a per-thread `LocalSandbox` (id `local:{thread_id}`) whose `path_mappings` resolve `/mnt/user-data/{workspace,uploads,outputs}` and `/mnt/acp-workspace` to that thread's host directories, so the public `Sandbox` API honours the `/mnt/user-data` contract uniformly with AIO. `acquire()` / `acquire(None)` keeps the legacy generic singleton (id `local`) for callers without a thread context. Per-thread sandboxes are held in an LRU cache (default 256 entries) guarded by a `threading.Lock`. Legacy global-custom mounts are gated by the same user-scoped skill discovery rule used for prompt/list visibility; providers must not infer visibility from raw directory presence alone.
+- `AioSandboxProvider` (`packages/harness/deerflow/community/`) - Docker-based isolation. Active-cache and warm-pool entries are checked with the backend during acquire/reuse; definitively dead containers are dropped from all in-process maps so the thread can discover or create a fresh sandbox instead of reusing a stale client. Backend health-check failures are treated as unknown, not dead; local discovery likewise treats an unverifiable container as not adoptable and falls through to create rather than failing acquire. `get()` remains an in-memory lookup for event-loop-safe tool paths. Legacy global-custom mounts follow the same shared visibility helper as local and remote providers.
 - `BoxliteProvider` (`packages/harness/deerflow/community/boxlite/`) - BoxLite micro-VM isolation. The `boxlite` runtime is optional (`deerflow-harness[boxlite]`) and lazy-imported only when this provider is selected. The provider owns one private asyncio event loop on a daemon thread because BoxLite handles are loop-affine; sync `Sandbox` calls marshal onto that loop with `run_coroutine_threadsafe`.
   Boxes are named deterministically from `user_id:thread_id`, released into an in-process warm pool after each agent turn, and reclaimed only by the same user/thread. Warm-pool health checks use a short explicit timeout and forward that timeout through both BoxLite `exec(timeout=...)` and the private-loop `.result(timeout)` bridge so a hung VM cannot pin the per-thread acquire lock indefinitely.
   `sandbox.replicas` caps active + warm VMs per gateway process; if capacity is exhausted, only warm-pool VMs are evicted. `sandbox.idle_timeout` stops idle warm VMs after the configured seconds. `reset()` is intentionally a lightweight registry clear for `reset_sandbox_provider()` and does not close boxes, stop the idle reaper, or close the private loop; full teardown remains `shutdown()`.
diff --git a/backend/packages/harness/deerflow/community/aio_sandbox/aio_sandbox_provider.py b/backend/packages/harness/deerflow/community/aio_sandbox/aio_sandbox_provider.py
index 8874cd47e..663d1cbd3 100644
--- a/backend/packages/harness/deerflow/community/aio_sandbox/aio_sandbox_provider.py
+++ b/backend/packages/harness/deerflow/community/aio_sandbox/aio_sandbox_provider.py
@@ -36,10 +36,11 @@ from deerflow.community.warm_pool_lifecycle import (
     IDLE_CHECK_INTERVAL as _SHARED_IDLE_CHECK_INTERVAL,
 )
 from deerflow.config import get_app_config
-from deerflow.config.paths import VIRTUAL_PATH_PREFIX, get_paths
+from deerflow.config.paths import VIRTUAL_PATH_PREFIX, get_paths, join_host_path
 from deerflow.runtime.user_context import get_effective_user_id
 from deerflow.sandbox.sandbox import Sandbox
 from deerflow.sandbox.sandbox_provider import SandboxProvider
+from deerflow.skills.storage import user_should_see_legacy_skills
 
 from .aio_sandbox import AioSandbox
 from .backend import SandboxBackend, wait_for_sandbox_ready, wait_for_sandbox_ready_async
@@ -308,10 +309,10 @@ class AioSandboxProvider(WarmPoolLifecycleMixin[SandboxInfo], SandboxProvider):
             mounts.extend(self._get_thread_mounts(thread_id, user_id=user_id))
             logger.info(f"Adding thread mounts for thread {thread_id}: {mounts}")
 
-        skills_mount = self._get_skills_mount()
-        if skills_mount:
-            mounts.append(skills_mount)
-            logger.info(f"Adding skills mount: {skills_mount}")
+        skills_mounts = self._get_skills_mounts(user_id=user_id)
+        if skills_mounts:
+            mounts.extend(skills_mounts)
+            logger.info(f"Adding skills mounts: {skills_mounts}")
 
         return mounts
 
@@ -337,24 +338,76 @@ class AioSandboxProvider(WarmPoolLifecycleMixin[SandboxInfo], SandboxProvider):
         ]
 
     @staticmethod
-    def _get_skills_mount() -> tuple[str, str, bool] | None:
-        """Get the skills directory mount configuration.
+    def _get_skills_mounts(*, user_id: str | None = None) -> list[tuple[str, str, bool]]:
+        """Get skills directory mount configurations for three-way skills layout.
 
-        Mount source uses DEER_FLOW_HOST_SKILLS_PATH when running inside Docker (DooD)
-        so the host Docker daemon can resolve the path.
+        Mirrors ``LocalSandboxProvider._build_thread_path_mappings`` for AIO
+        sandboxes: public, per-user custom, and legacy (pre-migration
+        global-custom) skills are mounted to separate container subdirectories so
+        that ``Skill.get_container_path()`` category-aware paths resolve
+        correctly inside the sandbox.
+
+        Mount sources use ``DEER_FLOW_HOST_SKILLS_PATH`` and
+        ``DEER_FLOW_HOST_BASE_DIR`` when running inside Docker (DooD) so the
+        host Docker daemon can resolve the paths.
         """
+        mounts: list[tuple[str, str, bool]] = []
         try:
             config = get_app_config()
             skills_path = config.skills.get_skills_path()
             container_path = config.skills.container_path
 
-            if skills_path.exists():
-                # When running inside Docker with DooD, use host-side skills path.
-                host_skills = os.environ.get("DEER_FLOW_HOST_SKILLS_PATH") or str(skills_path)
-                return (host_skills, container_path, True)  # Read-only for security
+            # When running inside Docker with DooD, use host-side skills path.
+            host_skills_root = os.environ.get("DEER_FLOW_HOST_SKILLS_PATH") or str(skills_path)
+
+            # 1. Public skills: global, read-only — static, shared by all threads
+            public_skills_path = skills_path / "public"
+            if public_skills_path.exists():
+                mounts.append(
+                    (
+                        join_host_path(host_skills_root, "public"),
+                        f"{container_path}/public",
+                        True,
+                    )
+                )
+
+            # 2. Per-user custom skills: read-only, per-thread/per-user
+            effective_user_id = AioSandboxProvider._effective_acquire_user_id(user_id)
+            paths = get_paths()
+            user_custom_path = paths.user_custom_skills_dir(effective_user_id)
+            user_custom_path.mkdir(parents=True, exist_ok=True)
+
+            host_user_custom = join_host_path(
+                str(paths.host_base_dir),
+                "users",
+                effective_user_id,
+                "skills",
+                "custom",
+            )
+            mounts.append(
+                (
+                    host_user_custom,
+                    f"{container_path}/custom",
+                    True,
+                )
+            )
+
+            # 3. Legacy (pre-migration global-custom) skills: only mount for
+            #    users who have no per-user custom skills yet, mirroring
+            #    ``UserScopedSkillStorage._iter_skill_files`` visibility rule.
+            legacy_skills_path = skills_path / "custom"
+            if user_should_see_legacy_skills(effective_user_id, host_path=str(skills_path)) and legacy_skills_path.exists():
+                mounts.append(
+                    (
+                        join_host_path(host_skills_root, "custom"),
+                        f"{container_path}/legacy",
+                        True,
+                    )
+                )
         except Exception as e:
-            logger.warning(f"Could not setup skills mount: {e}")
-        return None
+            logger.warning("Could not setup skills mounts: %s", e)
+
+        return mounts
 
     # ── Idle timeout management ──────────────────────────────────────────
 
diff --git a/backend/packages/harness/deerflow/community/aio_sandbox/remote_backend.py b/backend/packages/harness/deerflow/community/aio_sandbox/remote_backend.py
index ee9848d48..9c448c4a5 100644
--- a/backend/packages/harness/deerflow/community/aio_sandbox/remote_backend.py
+++ b/backend/packages/harness/deerflow/community/aio_sandbox/remote_backend.py
@@ -22,6 +22,7 @@ import logging
 import requests
 
 from deerflow.runtime.user_context import get_effective_user_id
+from deerflow.skills.storage import user_should_see_legacy_skills
 
 from .backend import SandboxBackend
 from .sandbox_info import SandboxInfo
@@ -145,6 +146,7 @@ class RemoteSandboxBackend(SandboxBackend):
         """POST /api/sandboxes → create Pod + Service."""
         del extra_mounts
         effective_user_id = user_id or get_effective_user_id()
+        include_legacy_skills = user_should_see_legacy_skills(effective_user_id)
         try:
             resp = requests.post(
                 f"{self._provisioner_url}/api/sandboxes",
@@ -152,6 +154,7 @@ class RemoteSandboxBackend(SandboxBackend):
                     "sandbox_id": sandbox_id,
                     "thread_id": thread_id,
                     "user_id": effective_user_id,
+                    "include_legacy_skills": include_legacy_skills,
                 },
                 timeout=30,
             )
diff --git a/backend/packages/harness/deerflow/sandbox/local/local_sandbox_provider.py b/backend/packages/harness/deerflow/sandbox/local/local_sandbox_provider.py
index 192fc3271..c02f2cb32 100644
--- a/backend/packages/harness/deerflow/sandbox/local/local_sandbox_provider.py
+++ b/backend/packages/harness/deerflow/sandbox/local/local_sandbox_provider.py
@@ -6,6 +6,7 @@ from pathlib import Path
 from deerflow.sandbox.local.local_sandbox import LocalSandbox, PathMapping
 from deerflow.sandbox.sandbox import Sandbox
 from deerflow.sandbox.sandbox_provider import SandboxProvider
+from deerflow.skills.storage import user_should_see_legacy_skills
 
 logger = logging.getLogger(__name__)
 
@@ -310,8 +311,7 @@ class LocalSandboxProvider(SandboxProvider):
             skills_container_path = config.skills.container_path
             user_custom_path = paths.user_custom_skills_dir(effective_user_id)
             legacy_skills_path = config.skills.get_skills_path() / "custom"
-            user_has_no_custom_skills = not any(p.is_dir() and not p.name.startswith(".") for p in user_custom_path.iterdir()) if user_custom_path.exists() else True
-            if user_has_no_custom_skills and legacy_skills_path.exists() and any((legacy_skills_path / d / "SKILL.md").exists() for d in legacy_skills_path.iterdir() if d.is_dir() and not d.name.startswith(".")):
+            if user_should_see_legacy_skills(effective_user_id, host_path=str(config.skills.get_skills_path())) and legacy_skills_path.exists():
                 mappings.append(
                     PathMapping(
                         container_path=f"{skills_container_path}/legacy",
diff --git a/backend/packages/harness/deerflow/skills/storage/__init__.py b/backend/packages/harness/deerflow/skills/storage/__init__.py
index f91a1ace0..1d8940140 100644
--- a/backend/packages/harness/deerflow/skills/storage/__init__.py
+++ b/backend/packages/harness/deerflow/skills/storage/__init__.py
@@ -12,6 +12,7 @@ from collections import OrderedDict
 from deerflow.skills.storage.local_skill_storage import LocalSkillStorage
 from deerflow.skills.storage.skill_storage import SkillStorage
 from deerflow.skills.storage.user_scoped_skill_storage import UserScopedSkillStorage
+from deerflow.skills.types import SkillCategory
 
 logger = logging.getLogger(__name__)
 
@@ -142,6 +143,22 @@ def get_or_new_user_skill_storage(user_id: str, **kwargs) -> SkillStorage:
         return cached
 
 
+def user_should_see_legacy_skills(user_id: str, **kwargs) -> bool:
+    """Return whether discovery exposes any LEGACY skills for this user.
+
+    Sandbox mounts must not be more permissive than skill discovery. This
+    helper centralizes that contract so local, AIO, and remote providers all
+    follow the same visibility rule.
+    """
+    if kwargs:
+        from deerflow.config.paths import make_safe_user_id
+
+        storage = UserScopedSkillStorage(make_safe_user_id(user_id), **kwargs)
+    else:
+        storage = get_or_new_user_skill_storage(user_id)
+    return any((skill.category.value if hasattr(skill.category, "value") else skill.category) == SkillCategory.LEGACY.value for skill in storage.load_skills(enabled_only=False))
+
+
 def reset_skill_storage() -> None:
     """Clear all cached storage instances (used in tests and hot-reload scenarios)."""
     global _default_skill_storage, _default_skill_storage_config
@@ -180,6 +197,7 @@ __all__ = [
     "UserScopedSkillStorage",
     "get_or_new_skill_storage",
     "get_or_new_user_skill_storage",
+    "user_should_see_legacy_skills",
     "reset_skill_storage",
     "reset_user_skill_storage",
 ]
diff --git a/backend/tests/test_aio_sandbox_provider.py b/backend/tests/test_aio_sandbox_provider.py
index e0349f0a0..df1745873 100644
--- a/backend/tests/test_aio_sandbox_provider.py
+++ b/backend/tests/test_aio_sandbox_provider.py
@@ -373,6 +373,7 @@ def test_remote_backend_create_forwards_effective_user_id(monkeypatch):
         return _Response()
 
     monkeypatch.setattr(remote_mod.requests, "post", _post)
+    monkeypatch.setattr(remote_mod, "user_should_see_legacy_skills", lambda user_id: True)
 
     try:
         backend.create("thread-42", "sandbox-42")
@@ -384,6 +385,7 @@ def test_remote_backend_create_forwards_effective_user_id(monkeypatch):
         "sandbox_id": "sandbox-42",
         "thread_id": "thread-42",
         "user_id": "user-7",
+        "include_legacy_skills": True,
     }
 
 
@@ -406,10 +408,12 @@ def test_remote_backend_create_prefers_explicit_user_id(monkeypatch):
 
     monkeypatch.setattr(remote_mod.requests, "post", _post)
     monkeypatch.setattr(remote_mod, "get_effective_user_id", lambda: "default")
+    monkeypatch.setattr(remote_mod, "user_should_see_legacy_skills", lambda user_id: False)
 
     backend.create("thread-42", "sandbox-42", user_id="ou-user")
 
     assert posted["json"]["user_id"] == "ou-user"
+    assert posted["json"]["include_legacy_skills"] is False
 
 
 # ── Sandbox client teardown (#2872) ──────────────────────────────────────────
diff --git a/backend/tests/test_provisioner_pvc_volumes.py b/backend/tests/test_provisioner_pvc_volumes.py
index d5b66a2c7..2d0668de3 100644
--- a/backend/tests/test_provisioner_pvc_volumes.py
+++ b/backend/tests/test_provisioner_pvc_volumes.py
@@ -1,40 +1,84 @@
-"""Regression tests for provisioner PVC volume support."""
+"""Regression tests for provisioner three-way skills + PVC volume support."""
 
 
 # ── _build_volumes ─────────────────────────────────────────────────────
 
 
 class TestBuildVolumes:
-    """Tests for _build_volumes: PVC vs hostPath selection."""
+    """Tests for _build_volumes: hostPath three-way vs PVC fallback."""
 
-    def test_default_uses_hostpath_for_skills(self, provisioner_module):
-        """When SKILLS_PVC_NAME is empty, skills volume should use hostPath."""
+    # ── hostPath mode (default) ────────────────────────────────────────
+
+    def test_hostpath_without_legacy_returns_three_volumes(self, provisioner_module):
+        """hostPath mode omits legacy volume unless the backend requests it."""
         provisioner_module.SKILLS_PVC_NAME = ""
-        volumes = provisioner_module._build_volumes("thread-1")
-        skills_vol = volumes[0]
-        assert skills_vol.host_path is not None
-        assert skills_vol.host_path.path == provisioner_module.SKILLS_HOST_PATH
-        assert skills_vol.host_path.type == "Directory"
-        assert skills_vol.persistent_volume_claim is None
-
-    def test_default_uses_hostpath_for_userdata(self, provisioner_module):
-        """When USERDATA_PVC_NAME is empty, user-data volume should use hostPath."""
         provisioner_module.USERDATA_PVC_NAME = ""
         volumes = provisioner_module._build_volumes("thread-1")
-        userdata_vol = volumes[1]
-        assert userdata_vol.host_path is not None
-        assert userdata_vol.persistent_volume_claim is None
+        assert len(volumes) == 3
+
+    def test_hostpath_skills_public_volume(self, provisioner_module):
+        """First skills volume mounts public/ subdirectory."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        volumes = provisioner_module._build_volumes("thread-1")
+        pub = volumes[0]
+        assert pub.name == "skills-public"
+        assert pub.host_path is not None
+        assert pub.host_path.path.endswith("/public")
+        assert pub.host_path.type == "Directory"
+        assert pub.persistent_volume_claim is None
+
+    def test_hostpath_skills_custom_volume(self, provisioner_module):
+        """Second skills volume mounts per-user custom directory."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        volumes = provisioner_module._build_volumes("thread-1", user_id="user-7")
+        custom = volumes[1]
+        assert custom.name == "skills-custom"
+        assert custom.host_path is not None
+        assert "users/user-7/skills/custom" in custom.host_path.path
+        assert custom.host_path.type == "DirectoryOrCreate"
+
+    def test_hostpath_skills_legacy_volume(self, provisioner_module):
+        """Legacy global-custom directory is mounted only when requested."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        volumes = provisioner_module._build_volumes(
+            "thread-1",
+            include_legacy_skills=True,
+        )
+        legacy = volumes[2]
+        assert legacy.name == "skills-legacy"
+        assert legacy.host_path is not None
+        assert legacy.host_path.path.endswith("/custom")
+        assert legacy.host_path.type == "Directory"
+
+    def test_hostpath_without_legacy_has_no_legacy_volume(self, provisioner_module):
+        """Fresh installs should not require a missing global legacy directory."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        volumes = provisioner_module._build_volumes("thread-1")
+        assert [volume.name for volume in volumes] == [
+            "skills-public",
+            "skills-custom",
+            "user-data",
+        ]
 
     def test_hostpath_userdata_includes_thread_id(self, provisioner_module):
         """hostPath user-data path should include thread_id."""
         provisioner_module.USERDATA_PVC_NAME = ""
         volumes = provisioner_module._build_volumes("my-thread-42")
-        userdata_vol = volumes[1]
+        userdata_vol = volumes[-1]
         path = userdata_vol.host_path.path
         assert "my-thread-42" in path
         assert path.endswith("user-data")
         assert userdata_vol.host_path.type == "DirectoryOrCreate"
 
+    # ── PVC mode (single-volume fallback) ──────────────────────────────
+
+    def test_pvc_returns_two_volumes(self, provisioner_module):
+        """PVC mode falls back to 1 skills volume + 1 user-data volume."""
+        provisioner_module.SKILLS_PVC_NAME = "my-skills-pvc"
+        provisioner_module.USERDATA_PVC_NAME = ""
+        volumes = provisioner_module._build_volumes("thread-1")
+        assert len(volumes) == 2
+
     def test_skills_pvc_overrides_hostpath(self, provisioner_module):
         """When SKILLS_PVC_NAME is set, skills volume should use PVC."""
         provisioner_module.SKILLS_PVC_NAME = "my-skills-pvc"
@@ -49,7 +93,7 @@ class TestBuildVolumes:
         """When USERDATA_PVC_NAME is set, user-data volume should use PVC."""
         provisioner_module.USERDATA_PVC_NAME = "my-userdata-pvc"
         volumes = provisioner_module._build_volumes("thread-1")
-        userdata_vol = volumes[1]
+        userdata_vol = volumes[-1]
         assert userdata_vol.persistent_volume_claim is not None
         assert userdata_vol.persistent_volume_claim.claim_name == "my-userdata-pvc"
         assert userdata_vol.host_path is None
@@ -60,78 +104,112 @@ class TestBuildVolumes:
         provisioner_module.USERDATA_PVC_NAME = "userdata-pvc"
         volumes = provisioner_module._build_volumes("thread-1")
         assert volumes[0].persistent_volume_claim is not None
-        assert volumes[1].persistent_volume_claim is not None
+        assert volumes[-1].persistent_volume_claim is not None
 
-    def test_returns_two_volumes(self, provisioner_module):
-        """Should always return exactly two volumes."""
-        provisioner_module.SKILLS_PVC_NAME = ""
-        provisioner_module.USERDATA_PVC_NAME = ""
-        assert len(provisioner_module._build_volumes("t")) == 2
-
-        provisioner_module.SKILLS_PVC_NAME = "a"
-        provisioner_module.USERDATA_PVC_NAME = "b"
-        assert len(provisioner_module._build_volumes("t")) == 2
-
-    def test_volume_names_are_stable(self, provisioner_module):
-        """Volume names must stay 'skills' and 'user-data'."""
+    def test_pvc_volume_names_are_stable(self, provisioner_module):
+        """PVC mode volume names must stay 'skills' and 'user-data'."""
+        provisioner_module.SKILLS_PVC_NAME = "x"
         volumes = provisioner_module._build_volumes("thread-1")
         assert volumes[0].name == "skills"
-        assert volumes[1].name == "user-data"
+        assert volumes[-1].name == "user-data"
 
 
 # ── _build_volume_mounts ───────────────────────────────────────────────
 
 
 class TestBuildVolumeMounts:
-    """Tests for _build_volume_mounts: mount paths and subPath behavior."""
+    """Tests for _build_volume_mounts: three-way mount paths and subPath."""
 
-    def test_default_no_subpath(self, provisioner_module):
+    # ── hostPath mode ──────────────────────────────────────────────────
+
+    def test_hostpath_without_legacy_returns_three_mounts(self, provisioner_module):
+        """hostPath mode omits legacy mount unless the backend requests it."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        assert len(mounts) == 3
+
+    def test_hostpath_skills_public_mount(self, provisioner_module):
+        """Public skills mount at /mnt/skills/public, read-only."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        assert mounts[0].name == "skills-public"
+        assert mounts[0].mount_path == "/mnt/skills/public"
+        assert mounts[0].read_only is True
+
+    def test_hostpath_skills_custom_mount(self, provisioner_module):
+        """Per-user custom skills mount at /mnt/skills/custom, read-only."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        assert mounts[1].name == "skills-custom"
+        assert mounts[1].mount_path == "/mnt/skills/custom"
+        assert mounts[1].read_only is True
+
+    def test_hostpath_skills_legacy_mount(self, provisioner_module):
+        """Legacy skills mount at /mnt/skills/legacy, read-only."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        mounts = provisioner_module._build_volume_mounts(
+            "thread-1",
+            include_legacy_skills=True,
+        )
+        assert mounts[2].name == "skills-legacy"
+        assert mounts[2].mount_path == "/mnt/skills/legacy"
+        assert mounts[2].read_only is True
+
+    def test_hostpath_without_legacy_has_no_legacy_mount(self, provisioner_module):
+        """Users with custom skills should not see hidden legacy content in the sandbox."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        assert [mount.name for mount in mounts] == [
+            "skills-public",
+            "skills-custom",
+            "user-data",
+        ]
+
+    def test_hostpath_userdata_read_write(self, provisioner_module):
+        """User-data mount should always be read-write."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        userdata = mounts[-1]
+        assert userdata.name == "user-data"
+        assert userdata.mount_path == "/mnt/user-data"
+        assert userdata.read_only is False
+
+    # ── PVC mode ───────────────────────────────────────────────────────
+
+    def test_pvc_returns_two_mounts(self, provisioner_module):
+        """PVC mode falls back to 1 skills mount + 1 user-data mount."""
+        provisioner_module.SKILLS_PVC_NAME = "x"
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        assert len(mounts) == 2
+
+    def test_pvc_skills_mount_is_single_root(self, provisioner_module):
+        """PVC mode skills mount is at /mnt/skills."""
+        provisioner_module.SKILLS_PVC_NAME = "x"
+        mounts = provisioner_module._build_volume_mounts("thread-1")
+        assert mounts[0].mount_path == "/mnt/skills"
+
+    def test_pvc_no_subpath_on_userdata(self, provisioner_module):
         """hostPath mode should not set sub_path on user-data mount."""
         provisioner_module.USERDATA_PVC_NAME = ""
         mounts = provisioner_module._build_volume_mounts("thread-1")
-        userdata_mount = mounts[1]
+        userdata_mount = mounts[-1]
         assert userdata_mount.sub_path is None
 
     def test_pvc_sets_user_scoped_subpath(self, provisioner_module):
         """PVC mode should include user_id in the user-data subPath."""
         provisioner_module.USERDATA_PVC_NAME = "my-pvc"
         mounts = provisioner_module._build_volume_mounts("thread-42", user_id="user-7")
-        userdata_mount = mounts[1]
+        userdata_mount = mounts[-1]
         assert userdata_mount.sub_path == "deer-flow/users/user-7/threads/thread-42/user-data"
 
     def test_pvc_defaults_to_default_user_subpath(self, provisioner_module):
         """Older callers should still land under a stable default user namespace."""
         provisioner_module.USERDATA_PVC_NAME = "my-pvc"
         mounts = provisioner_module._build_volume_mounts("thread-42")
-        userdata_mount = mounts[1]
+        userdata_mount = mounts[-1]
         assert userdata_mount.sub_path == "deer-flow/users/default/threads/thread-42/user-data"
 
-    def test_skills_mount_read_only(self, provisioner_module):
-        """Skills mount should always be read-only."""
-        mounts = provisioner_module._build_volume_mounts("thread-1")
-        assert mounts[0].read_only is True
-
-    def test_userdata_mount_read_write(self, provisioner_module):
-        """User-data mount should always be read-write."""
-        mounts = provisioner_module._build_volume_mounts("thread-1")
-        assert mounts[1].read_only is False
-
-    def test_mount_paths_are_stable(self, provisioner_module):
-        """Mount paths must stay /mnt/skills and /mnt/user-data."""
-        mounts = provisioner_module._build_volume_mounts("thread-1")
-        assert mounts[0].mount_path == "/mnt/skills"
-        assert mounts[1].mount_path == "/mnt/user-data"
-
-    def test_mount_names_match_volumes(self, provisioner_module):
-        """Mount names should match the volume names."""
-        mounts = provisioner_module._build_volume_mounts("thread-1")
-        assert mounts[0].name == "skills"
-        assert mounts[1].name == "user-data"
-
-    def test_returns_two_mounts(self, provisioner_module):
-        """Should always return exactly two mounts."""
-        assert len(provisioner_module._build_volume_mounts("t")) == 2
-
 
 # ── _build_pod integration ─────────────────────────────────────────────
 
@@ -139,16 +217,52 @@ class TestBuildVolumeMounts:
 class TestBuildPodVolumes:
     """Integration: _build_pod should wire volumes and mounts correctly."""
 
-    def test_pod_spec_has_volumes(self, provisioner_module):
-        """Pod spec should contain exactly 2 volumes."""
+    def test_pod_hostpath_without_legacy_has_three_volumes(self, provisioner_module):
+        """hostPath Pod spec should omit legacy volume by default."""
         provisioner_module.SKILLS_PVC_NAME = ""
         provisioner_module.USERDATA_PVC_NAME = ""
         pod = provisioner_module._build_pod("sandbox-1", "thread-1")
+        assert len(pod.spec.volumes) == 3
+
+    def test_pod_hostpath_without_legacy_has_three_mounts(self, provisioner_module):
+        """hostPath container should omit legacy mount by default."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        pod = provisioner_module._build_pod("sandbox-1", "thread-1")
+        assert len(pod.spec.containers[0].volume_mounts) == 3
+
+    def test_pod_hostpath_with_legacy_has_four_volumes(self, provisioner_module):
+        """Legacy volume should be present when the backend requests it."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        pod = provisioner_module._build_pod(
+            "sandbox-1",
+            "thread-1",
+            include_legacy_skills=True,
+        )
+        assert len(pod.spec.volumes) == 4
+
+    def test_pod_hostpath_with_legacy_has_four_mounts(self, provisioner_module):
+        """Legacy mount should be present when the backend requests it."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        pod = provisioner_module._build_pod(
+            "sandbox-1",
+            "thread-1",
+            include_legacy_skills=True,
+        )
+        assert len(pod.spec.containers[0].volume_mounts) == 4
+
+    def test_pod_pvc_has_two_volumes(self, provisioner_module):
+        """PVC Pod spec should contain exactly 2 volumes."""
+        provisioner_module.SKILLS_PVC_NAME = "skills-pvc"
+        provisioner_module.USERDATA_PVC_NAME = ""
+        pod = provisioner_module._build_pod("sandbox-1", "thread-1")
         assert len(pod.spec.volumes) == 2
 
-    def test_pod_spec_has_volume_mounts(self, provisioner_module):
-        """Container should have exactly 2 volume mounts."""
-        provisioner_module.SKILLS_PVC_NAME = ""
+    def test_pod_pvc_has_two_mounts(self, provisioner_module):
+        """PVC container should have exactly 2 volume mounts."""
+        provisioner_module.SKILLS_PVC_NAME = "skills-pvc"
         provisioner_module.USERDATA_PVC_NAME = ""
         pod = provisioner_module._build_pod("sandbox-1", "thread-1")
         assert len(pod.spec.containers[0].volume_mounts) == 2
@@ -159,6 +273,20 @@ class TestBuildPodVolumes:
         provisioner_module.USERDATA_PVC_NAME = "userdata-pvc"
         pod = provisioner_module._build_pod("sandbox-1", "thread-1", user_id="user-7")
         assert pod.spec.volumes[0].persistent_volume_claim is not None
-        assert pod.spec.volumes[1].persistent_volume_claim is not None
-        userdata_mount = pod.spec.containers[0].volume_mounts[1]
+        assert pod.spec.volumes[-1].persistent_volume_claim is not None
+        userdata_mount = pod.spec.containers[0].volume_mounts[-1]
         assert userdata_mount.sub_path == "deer-flow/users/user-7/threads/thread-1/user-data"
+
+    def test_pod_three_way_skills_mount_paths(self, provisioner_module):
+        """Ensure public/custom/legacy mount paths are correct."""
+        provisioner_module.SKILLS_PVC_NAME = ""
+        provisioner_module.USERDATA_PVC_NAME = ""
+        pod = provisioner_module._build_pod(
+            "sandbox-1",
+            "thread-1",
+            include_legacy_skills=True,
+        )
+        mount_paths = {m.name: m.mount_path for m in pod.spec.containers[0].volume_mounts}
+        assert mount_paths["skills-public"] == "/mnt/skills/public"
+        assert mount_paths["skills-custom"] == "/mnt/skills/custom"
+        assert mount_paths["skills-legacy"] == "/mnt/skills/legacy"
diff --git a/backend/tests/test_provisioner_request_threading.py b/backend/tests/test_provisioner_request_threading.py
index 24ea81b3a..a834d085d 100644
--- a/backend/tests/test_provisioner_request_threading.py
+++ b/backend/tests/test_provisioner_request_threading.py
@@ -27,6 +27,7 @@ class _RecordingCoreV1:
         self.ready_after_service_reads = ready_after_service_reads or {}
         self.service_read_counts: dict[str, int] = {}
         self.created_pods: list[str] = []
+        self.created_pod_specs: dict[str, object] = {}
         self.created_services: list[str] = []
 
     def _record_k8s_call(self) -> None:
@@ -58,6 +59,7 @@ class _RecordingCoreV1:
         self._record_k8s_call()
         sandbox_id = pod.metadata.labels["sandbox-id"]
         self.created_pods.append(sandbox_id)
+        self.created_pod_specs[sandbox_id] = pod
 
     def create_namespaced_service(self, _namespace: str, service) -> None:
         self._record_k8s_call()
@@ -157,3 +159,46 @@ async def test_sandbox_business_routes_run_k8s_client_off_event_loop_thread(
     if expected_created_sandbox is not None:
         assert fake_core_v1.created_pods == [expected_created_sandbox]
         assert fake_core_v1.created_services == [expected_created_sandbox]
+
+
+@pytest.mark.parametrize(
+    ("include_legacy_skills", "expected_mount_names"),
+    [
+        (
+            False,
+            ["skills-public", "skills-custom", "user-data"],
+        ),
+        (
+            True,
+            ["skills-public", "skills-custom", "skills-legacy", "user-data"],
+        ),
+    ],
+    ids=["without-legacy", "with-legacy"],
+)
+def test_create_sandbox_route_builds_expected_skills_mount_layout(
+    include_legacy_skills: bool,
+    expected_mount_names: list[str],
+    monkeypatch: pytest.MonkeyPatch,
+    provisioner_module,
+) -> None:
+    fake_core_v1 = _RecordingCoreV1(
+        event_loop_thread_id=-1,
+        ready_after_service_reads={"sandbox-layout": 1},
+    )
+    monkeypatch.setattr(provisioner_module, "core_v1", fake_core_v1)
+
+    response = provisioner_module.create_sandbox(
+        provisioner_module.CreateSandboxRequest(
+            sandbox_id="sandbox-layout",
+            thread_id="thread-1",
+            user_id="user-1",
+            include_legacy_skills=include_legacy_skills,
+        )
+    )
+
+    assert response.status == "Running"
+    pod = fake_core_v1.created_pod_specs["sandbox-layout"]
+    volume_names = [volume.name for volume in pod.spec.volumes]
+    mount_names = [mount.name for mount in pod.spec.containers[0].volume_mounts]
+    assert volume_names == expected_mount_names
+    assert mount_names == expected_mount_names
diff --git a/backend/tests/test_remote_sandbox_backend.py b/backend/tests/test_remote_sandbox_backend.py
index 6550cae10..f6abe4e08 100644
--- a/backend/tests/test_remote_sandbox_backend.py
+++ b/backend/tests/test_remote_sandbox_backend.py
@@ -3,8 +3,11 @@ from __future__ import annotations
 import pytest
 import requests
 
+import deerflow.skills.storage as storage_mod
+from deerflow.community.aio_sandbox import remote_backend as remote_backend_mod
 from deerflow.community.aio_sandbox.remote_backend import RemoteSandboxBackend
 from deerflow.community.aio_sandbox.sandbox_info import SandboxInfo
+from deerflow.skills.types import SkillCategory
 
 
 class _StubResponse:
@@ -123,6 +126,25 @@ def test_provisioner_list_skips_non_dict_sandbox_entries(monkeypatch):
     assert infos[0].sandbox_url == "http://k3s:31001"
 
 
+@pytest.mark.parametrize(
+    ("categories", "expected"),
+    [
+        ([SkillCategory.LEGACY], True),
+        (["legacy"], True),
+        ([SkillCategory.CUSTOM], False),
+    ],
+)
+def test_user_should_see_legacy_skills_follows_storage_visibility_rule(monkeypatch, categories, expected):
+    class _Storage:
+        def load_skills(self, *, enabled_only: bool = False):
+            assert enabled_only is False
+            return [type("SkillStub", (), {"category": category})() for category in categories]
+
+    monkeypatch.setattr(storage_mod, "get_or_new_user_skill_storage", lambda user_id: _Storage())
+
+    assert storage_mod.user_should_see_legacy_skills("user-1") is expected
+
+
 @pytest.mark.parametrize("expected_user_id", [None, "owner-1"])
 def test_create_delegates_to_provisioner_create(monkeypatch, expected_user_id):
     backend = RemoteSandboxBackend("http://provisioner:8002")
@@ -148,6 +170,7 @@ def test_create_delegates_to_provisioner_create(monkeypatch, expected_user_id):
 
 def test_provisioner_create_returns_sandbox_info(monkeypatch):
     backend = RemoteSandboxBackend("http://provisioner:8002")
+    monkeypatch.setattr(remote_backend_mod, "user_should_see_legacy_skills", lambda user_id: True)
 
     def mock_post(url: str, json: dict, timeout: int):
         assert url == "http://provisioner:8002/api/sandboxes"
@@ -155,6 +178,7 @@ def test_provisioner_create_returns_sandbox_info(monkeypatch):
             "sandbox_id": "abc123",
             "thread_id": "thread-1",
             "user_id": "test-user-autouse",
+            "include_legacy_skills": True,
         }
         assert timeout == 30
         return _StubResponse(payload={"sandbox_id": "abc123", "sandbox_url": "http://k3s:31001"})
@@ -168,6 +192,7 @@ def test_provisioner_create_returns_sandbox_info(monkeypatch):
 
 def test_provisioner_create_accepts_anonymous_thread_id(monkeypatch):
     backend = RemoteSandboxBackend("http://provisioner:8002")
+    monkeypatch.setattr(remote_backend_mod, "user_should_see_legacy_skills", lambda user_id: False)
 
     def mock_post(url: str, json: dict, timeout: int):
         assert url == "http://provisioner:8002/api/sandboxes"
@@ -175,6 +200,7 @@ def test_provisioner_create_accepts_anonymous_thread_id(monkeypatch):
             "sandbox_id": "anon123",
             "thread_id": None,
             "user_id": "test-user-autouse",
+            "include_legacy_skills": False,
         }
         assert timeout == 30
         return _StubResponse(payload={"sandbox_id": "anon123", "sandbox_url": "http://k3s:31002"})
@@ -188,6 +214,7 @@ def test_provisioner_create_accepts_anonymous_thread_id(monkeypatch):
 
 def test_provisioner_create_raises_runtime_error_on_request_exception(monkeypatch):
     backend = RemoteSandboxBackend("http://provisioner:8002")
+    monkeypatch.setattr(remote_backend_mod, "user_should_see_legacy_skills", lambda user_id: False)
 
     def mock_post(url: str, json: dict, timeout: int):
         raise requests.RequestException("boom")
diff --git a/backend/tests/test_three_way_skills_mount_e2e.py b/backend/tests/test_three_way_skills_mount_e2e.py
new file mode 100644
index 000000000..bb166740a
--- /dev/null
+++ b/backend/tests/test_three_way_skills_mount_e2e.py
@@ -0,0 +1,336 @@
+"""End-to-end tests for three-way skills mount across sandbox providers.
+
+Verifies that (a) public, (b) per-user custom, and (c) legacy global-custom
+skills all resolve to correct container paths that the sandbox providers
+actually mount — covering ``LocalSandboxProvider`` and
+``AioSandboxProvider`` (DooD / local-backend path).
+
+Includes a full-pipeline test that exercises the actual path the model
+takes: ``UserScopedSkillStorage`` category assignment → ``Skill.get_container_file_path()`` → ``sandbox.read_file()``.
+"""
+
+import importlib
+from pathlib import Path
+from types import SimpleNamespace
+from unittest.mock import patch
+
+import pytest
+
+from deerflow.config.paths import Paths
+from deerflow.sandbox.local.local_sandbox import PathMapping
+from deerflow.sandbox.local.local_sandbox_provider import LocalSandboxProvider
+from deerflow.skills.types import SKILL_MD_FILE, Skill, SkillCategory
+
+_AIO_MODULE = "deerflow.community.aio_sandbox.aio_sandbox_provider"
+_AIO_GET_CONFIG = f"{_AIO_MODULE}.get_app_config"
+
+
+def _write_skill(base: Path, name: str, description: str = "test skill") -> Path:
+    skill_dir = base / name
+    skill_dir.mkdir(parents=True, exist_ok=True)
+    skill_md = skill_dir / SKILL_MD_FILE
+    skill_md.write_text(
+        f"---\nname: {name}\ndescription: {description}\n---\n\n# {name}\n",
+        encoding="utf-8",
+    )
+    return skill_md
+
+
+def _build_config(skills_root: Path):
+    from deerflow.config.sandbox_config import SandboxConfig
+
+    return SimpleNamespace(
+        skills=SimpleNamespace(
+            container_path="/mnt/skills",
+            get_skills_path=lambda sk=skills_root: sk,
+            use="deerflow.skills.storage.local_skill_storage:LocalSkillStorage",
+        ),
+        sandbox=SandboxConfig(
+            use="deerflow.sandbox.local:LocalSandboxProvider",
+            mounts=[],
+        ),
+    )
+
+
+def _local_mounts(provider: LocalSandboxProvider, thread_id: str, user_id: str) -> dict[str, PathMapping]:
+    mappings = list(provider._path_mappings) + provider._build_thread_path_mappings(thread_id, user_id=user_id)
+    return {m.container_path: m for m in mappings}
+
+
+@pytest.fixture
+def skills_fs(tmp_path: Path) -> dict:
+    root = tmp_path / "skills"
+    pub = root / "public"
+    legacy = root / "custom"
+    users_dir = tmp_path / "users"
+    user_custom = users_dir / "user-1" / "skills" / "custom"
+
+    return {
+        "root": root,
+        "public": pub,
+        "legacy_global": legacy,
+        "user_custom": user_custom,
+        "users_dir": users_dir,
+        "pub_skill": _write_skill(pub, "pub-skill", "public skill"),
+        "legacy_skill": _write_skill(legacy, "leg-skill", "legacy skill"),
+        "user_skill": _write_skill(user_custom, "usr-skill", "user custom skill"),
+    }
+
+
+@pytest.fixture
+def aio_mod():
+    return importlib.import_module(_AIO_MODULE)
+
+
+class TestThreeWayMountEndToEnd:
+    # ── LocalSandboxProvider: mount structure ──────────────────────────
+
+    def test_local_public_skill_mounted(self, skills_fs):
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        with patch("deerflow.config.get_app_config", return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            provider = LocalSandboxProvider()
+            idx = _local_mounts(provider, "thread-1", user_id="user-1")
+        assert "/mnt/skills/public" in idx
+        assert idx["/mnt/skills/public"].read_only is True
+
+    def test_local_per_user_custom_skill_mounted(self, skills_fs):
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        with patch("deerflow.config.get_app_config", return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            provider = LocalSandboxProvider()
+            idx = _local_mounts(provider, "thread-1", user_id="user-1")
+        assert "/mnt/skills/custom" in idx
+        assert str(skills_fs["user_custom"]) in idx["/mnt/skills/custom"].local_path
+
+    def test_local_legacy_mounted_for_user_without_custom(self, skills_fs):
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        with patch("deerflow.config.get_app_config", return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            provider = LocalSandboxProvider()
+            idx = _local_mounts(provider, "thread-1", user_id="noob")
+        assert "/mnt/skills/legacy" in idx
+        assert str(skills_fs["legacy_global"]) in idx["/mnt/skills/legacy"].local_path
+
+    def test_local_legacy_not_mounted_when_user_has_custom(self, skills_fs):
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        with patch("deerflow.config.get_app_config", return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            provider = LocalSandboxProvider()
+            idx = _local_mounts(provider, "thread-1", user_id="user-1")
+        assert "/mnt/skills/legacy" not in idx
+
+    def test_local_legacy_still_mounted_when_user_has_only_non_skill_subdir(self, skills_fs):
+        (skills_fs["users_dir"] / "ghost" / "skills" / "custom" / "dangling-dir").mkdir(parents=True, exist_ok=True)
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        with patch("deerflow.config.get_app_config", return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            provider = LocalSandboxProvider()
+            idx = _local_mounts(provider, "thread-1", user_id="ghost")
+        assert "/mnt/skills/legacy" in idx
+
+    # ── LocalSandboxProvider: read_file on container paths ─────────────
+
+    def test_local_read_file_resolves_public_and_custom(self, skills_fs):
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        with patch("deerflow.config.get_app_config", return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            provider = LocalSandboxProvider()
+            sid = provider.acquire("thread-1", user_id="user-1")
+        sandbox = provider.get(sid)
+        assert "pub-skill" in sandbox.read_file("/mnt/skills/public/pub-skill/SKILL.md")
+        assert "usr-skill" in sandbox.read_file("/mnt/skills/custom/usr-skill/SKILL.md")
+
+    def test_local_read_file_resolves_legacy_skill(self, skills_fs):
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        with patch("deerflow.config.get_app_config", return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            provider = LocalSandboxProvider()
+            sid = provider.acquire("thread-1", user_id="noob")
+        sandbox = provider.get(sid)
+        assert "leg-skill" in sandbox.read_file("/mnt/skills/legacy/leg-skill/SKILL.md")
+
+    # ── Full pipeline: registry → container path → sandbox read ────────
+
+    def test_registry_to_sandbox_full_pipeline(self, skills_fs):
+        """Model's exact path: storage category → get_container_file_path → sandbox.read_file."""
+        from deerflow.skills.storage.user_scoped_skill_storage import UserScopedSkillStorage
+
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+
+        with patch("deerflow.config.get_app_config", return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            provider = LocalSandboxProvider()
+            sid_user = provider.acquire("t1", user_id="user-1")
+            sid_noob = provider.acquire("t2", user_id="noob")
+        sandbox_user = provider.get(sid_user)
+        sandbox_noob = provider.get(sid_noob)
+
+        # user-1 storage: sees public + custom, no legacy
+        with patch("deerflow.config.paths.get_paths", return_value=paths):
+            storage = UserScopedSkillStorage(user_id="user-1", host_path=str(skills_fs["root"]))
+            skills = list(storage._iter_skill_files())
+        by_name = {sf.parent.name: (cat, sf) for cat, _root, sf in skills}
+
+        # public
+        assert "pub-skill" in by_name
+        cat, _ = by_name["pub-skill"]
+        assert cat == SkillCategory.PUBLIC
+        s = Skill(name="pub-skill", description="p", license=None, skill_dir=skills_fs["public"] / "pub-skill", skill_file=skills_fs["pub_skill"], relative_path=Path("pub-skill"), category=cat)
+        cp = s.get_container_file_path("/mnt/skills")
+        assert cp == "/mnt/skills/public/pub-skill/SKILL.md"
+        assert "pub-skill" in sandbox_user.read_file(cp)
+
+        # custom
+        assert "usr-skill" in by_name
+        cat, _ = by_name["usr-skill"]
+        assert cat == SkillCategory.CUSTOM
+        s = Skill(name="usr-skill", description="u", license=None, skill_dir=skills_fs["user_custom"] / "usr-skill", skill_file=skills_fs["user_skill"], relative_path=Path("usr-skill"), category=cat)
+        cp = s.get_container_file_path("/mnt/skills")
+        assert cp == "/mnt/skills/custom/usr-skill/SKILL.md"
+        assert "usr-skill" in sandbox_user.read_file(cp)
+
+        # noob storage: sees public + legacy (no per-user custom)
+        with patch("deerflow.config.paths.get_paths", return_value=paths):
+            storage = UserScopedSkillStorage(user_id="noob", host_path=str(skills_fs["root"]))
+            skills = list(storage._iter_skill_files())
+        by_name = {sf.parent.name: (cat, sf) for cat, _root, sf in skills}
+
+        assert "leg-skill" in by_name
+        cat, _ = by_name["leg-skill"]
+        assert cat == SkillCategory.LEGACY
+        s = Skill(name="leg-skill", description="l", license=None, skill_dir=skills_fs["legacy_global"] / "leg-skill", skill_file=skills_fs["legacy_skill"], relative_path=Path("leg-skill"), category=cat)
+        cp = s.get_container_file_path("/mnt/skills")
+        assert cp == "/mnt/skills/legacy/leg-skill/SKILL.md"
+        assert "leg-skill" in sandbox_noob.read_file(cp)
+
+    # ── AioSandboxProvider ──────────────────────────────────────────────
+
+    def test_aio_public_skill_mount(self, skills_fs, aio_mod):
+        cfg = _build_config(skills_fs["root"])
+        with patch(_AIO_GET_CONFIG, return_value=cfg):
+            mounts = aio_mod.AioSandboxProvider._get_skills_mounts(user_id="user-1")
+        idx = {m[1]: m for m in mounts}
+        assert "/mnt/skills/public" in idx
+
+    def test_aio_per_user_custom_skill_mount(self, skills_fs, aio_mod, monkeypatch):
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        monkeypatch.setattr(aio_mod, "get_paths", lambda: paths)
+        with patch(_AIO_GET_CONFIG, return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            mounts = aio_mod.AioSandboxProvider._get_skills_mounts(user_id="user-1")
+        idx = {m[1]: m for m in mounts}
+        assert "/mnt/skills/custom" in idx
+        host, _, _ = idx["/mnt/skills/custom"]
+        assert "users/user-1/skills/custom" in host.replace("\\", "/")
+
+    def test_aio_legacy_mounted_for_user_without_custom(self, skills_fs, aio_mod, monkeypatch):
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        monkeypatch.setattr(aio_mod, "get_paths", lambda: paths)
+        with patch(_AIO_GET_CONFIG, return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            mounts = aio_mod.AioSandboxProvider._get_skills_mounts(user_id="noob")
+        idx = {m[1]: m for m in mounts}
+        assert "/mnt/skills/legacy" in idx
+
+    def test_aio_legacy_not_mounted_when_user_has_custom(self, skills_fs, aio_mod, monkeypatch):
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        monkeypatch.setattr(aio_mod, "get_paths", lambda: paths)
+        with patch(_AIO_GET_CONFIG, return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            mounts = aio_mod.AioSandboxProvider._get_skills_mounts(user_id="user-1")
+        idx = {m[1]: m for m in mounts}
+        assert "/mnt/skills/legacy" not in idx
+
+    def test_aio_legacy_still_mounted_when_user_has_only_non_skill_subdir(self, skills_fs, aio_mod, monkeypatch):
+        (skills_fs["users_dir"] / "ghost" / "skills" / "custom" / "dangling-dir").mkdir(parents=True, exist_ok=True)
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        monkeypatch.setattr(aio_mod, "get_paths", lambda: paths)
+        with patch(_AIO_GET_CONFIG, return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            mounts = aio_mod.AioSandboxProvider._get_skills_mounts(user_id="ghost")
+        idx = {m[1]: m for m in mounts}
+        assert "/mnt/skills/legacy" in idx
+
+    # ── AIO → Docker --mount translation ───────────────────────────────
+
+    def test_aio_extra_mounts_translate_to_docker_bind_mounts(self, skills_fs, aio_mod, monkeypatch):
+        """extra_mounts → _format_container_mount → correct Docker --mount args."""
+        from deerflow.community.aio_sandbox.local_backend import _format_container_mount
+
+        cfg = _build_config(skills_fs["root"])
+        paths = Paths(base_dir=skills_fs["users_dir"].parent)
+        monkeypatch.setattr(aio_mod, "get_paths", lambda: paths)
+
+        with patch(_AIO_GET_CONFIG, return_value=cfg), patch("deerflow.config.paths.get_paths", return_value=paths):
+            extra = aio_mod.AioSandboxProvider._get_extra_mounts(
+                aio_mod.AioSandboxProvider.__new__(aio_mod.AioSandboxProvider),
+                "thread-1",
+                user_id="noob",
+            )
+
+        # extra includes thread mounts + skills mounts
+        docker_args: list[str] = []
+        mount_entries: dict[str, str] = {}
+        for host, container, ro in extra:
+            args = _format_container_mount("docker", host, container, ro)
+            docker_args.extend(args)
+            if args[0] == "--mount":
+                mount_entries[container] = args[1]
+
+        assert "--mount" in docker_args
+        # Skills mounts must be present
+        assert "/mnt/skills/public" in mount_entries
+        assert "dst=/mnt/skills/public" in mount_entries["/mnt/skills/public"]
+        assert "readonly" in mount_entries["/mnt/skills/public"]
+
+        assert "/mnt/skills/custom" in mount_entries
+        assert "dst=/mnt/skills/custom" in mount_entries["/mnt/skills/custom"]
+        assert "users/noob/skills/custom" in mount_entries["/mnt/skills/custom"]
+
+        # noob has no per-user custom → legacy is mounted
+        assert "/mnt/skills/legacy" in mount_entries
+        assert "dst=/mnt/skills/legacy" in mount_entries["/mnt/skills/legacy"]
+
+    # ── Path alignment ──────────────────────────────────────────────────
+
+    def test_skill_container_paths_match_expected_mounts(self, skills_fs):
+        cr = "/mnt/skills"
+        assert (
+            Skill(
+                name="p",
+                description="",
+                license=None,
+                skill_dir=skills_fs["public"] / "pub-skill",
+                skill_file=skills_fs["pub_skill"],
+                relative_path=Path("pub-skill"),
+                category=SkillCategory.PUBLIC,
+            ).get_container_path(cr)
+            == "/mnt/skills/public/pub-skill"
+        )
+
+        assert (
+            Skill(
+                name="u",
+                description="",
+                license=None,
+                skill_dir=skills_fs["user_custom"] / "usr-skill",
+                skill_file=skills_fs["user_skill"],
+                relative_path=Path("usr-skill"),
+                category=SkillCategory.CUSTOM,
+            ).get_container_path(cr)
+            == "/mnt/skills/custom/usr-skill"
+        )
+
+        assert (
+            Skill(
+                name="l",
+                description="",
+                license=None,
+                skill_dir=skills_fs["legacy_global"] / "leg-skill",
+                skill_file=skills_fs["legacy_skill"],
+                relative_path=Path("leg-skill"),
+                category=SkillCategory.LEGACY,
+            ).get_container_path(cr)
+            == "/mnt/skills/legacy/leg-skill"
+        )
diff --git a/docker/docker-compose-dev.yaml b/docker/docker-compose-dev.yaml
index 19ffc2e4c..69c185baa 100644
--- a/docker/docker-compose-dev.yaml
+++ b/docker/docker-compose-dev.yaml
@@ -52,6 +52,8 @@ services:
       #   export DEER_FLOW_ROOT=/absolute/path/to/deer-flow
       - SKILLS_HOST_PATH=${DEER_FLOW_ROOT}/skills
       - THREADS_HOST_PATH=${DEER_FLOW_ROOT}/backend/.deer-flow/threads
+      # Per-user data base directory for user-scoped skill mounts
+      - DEER_FLOW_HOST_BASE_DIR=${DEER_FLOW_ROOT}/backend/.deer-flow
       # Production: use PVC instead of hostPath to avoid data loss on node failure.
       # When set, hostPath vars above are ignored for the corresponding volume.
       # USERDATA_PVC_NAME uses subPath (deer-flow/users/{user_id}/threads/{thread_id}/user-data) automatically.
diff --git a/docker/docker-compose.yaml b/docker/docker-compose.yaml
index 30e7880b5..32b07f7a7 100644
--- a/docker/docker-compose.yaml
+++ b/docker/docker-compose.yaml
@@ -158,6 +158,7 @@ services:
       - SANDBOX_IMAGE=enterprise-public-cn-beijing.cr.volces.com/vefaas-public/all-in-one-sandbox:latest
       - SKILLS_HOST_PATH=${DEER_FLOW_REPO_ROOT}/skills
       - THREADS_HOST_PATH=${DEER_FLOW_HOME}/threads
+      - DEER_FLOW_HOST_BASE_DIR=${DEER_FLOW_HOME}
       - KUBECONFIG_PATH=/root/.kube/config
       - NODE_HOST=host.docker.internal
       - K8S_API_SERVER=https://host.docker.internal:26443
diff --git a/docker/provisioner/app.py b/docker/provisioner/app.py
index 8015ba5ea..77f559c5f 100644
--- a/docker/provisioner/app.py
+++ b/docker/provisioner/app.py
@@ -60,6 +60,7 @@ SANDBOX_IMAGE = os.environ.get(
 )
 SKILLS_HOST_PATH = os.environ.get("SKILLS_HOST_PATH", "/skills")
 THREADS_HOST_PATH = os.environ.get("THREADS_HOST_PATH", "/.deer-flow/threads")
+DEER_FLOW_HOST_BASE_DIR = os.environ.get("DEER_FLOW_HOST_BASE_DIR", "/.deer-flow")
 SKILLS_PVC_NAME = os.environ.get("SKILLS_PVC_NAME", "")
 USERDATA_PVC_NAME = os.environ.get("USERDATA_PVC_NAME", "")
 SANDBOX_CONTAINER_PORT_RAW = os.environ.get("SANDBOX_CONTAINER_PORT", "8080")
@@ -227,6 +228,7 @@ class CreateSandboxRequest(BaseModel):
     sandbox_id: str
     thread_id: str = Field(pattern=SAFE_THREAD_ID_PATTERN)
     user_id: str = Field(default=DEFAULT_USER_ID, pattern=SAFE_USER_ID_PATTERN)
+    include_legacy_skills: bool = False
 
 
 class SandboxResponse(BaseModel):
@@ -250,26 +252,79 @@ def _sandbox_url(node_port: int) -> str:
     """Build the sandbox URL using the configured NODE_HOST."""
     return f"http://{NODE_HOST}:{node_port}"
 
+def _build_volumes(
+    thread_id: str,
+    user_id: str = DEFAULT_USER_ID,
+    *,
+    include_legacy_skills: bool = False,
+) -> list[k8s_client.V1Volume]:
+    """Build volume list: PVC when configured, otherwise hostPath.
+
+    Skills are split into public, per-user custom, and legacy (global-custom)
+    volumes so that ``/mnt/skills/{public,custom,legacy}/`` paths resolve
+    correctly inside the sandbox — matching the hostPath layout produced by
+    ``LocalSandboxProvider`` and ``AioSandboxProvider``.
+    """
+    volumes: list[k8s_client.V1Volume] = []
+
+    # ── Skills volumes ────────────────────────────────────────────────
 
-def _build_volumes(thread_id: str) -> list[k8s_client.V1Volume]:
-    """Build volume list: PVC when configured, otherwise hostPath."""
     if SKILLS_PVC_NAME:
-        skills_vol = k8s_client.V1Volume(
-            name="skills",
-            persistent_volume_claim=k8s_client.V1PersistentVolumeClaimVolumeSource(
-                claim_name=SKILLS_PVC_NAME,
-                read_only=True,
-            ),
+        # PVC mode: three-way subPath not yet supported; fall back to
+        # single-volume mount for backward compatibility.
+        logger.warning(
+            "SKILLS_PVC_NAME is set — three-way skills layout is not "
+            "supported in PVC mode yet; falling back to single /mnt/skills mount"
+        )
+        volumes.append(
+            k8s_client.V1Volume(
+                name="skills",
+                persistent_volume_claim=k8s_client.V1PersistentVolumeClaimVolumeSource(
+                    claim_name=SKILLS_PVC_NAME,
+                    read_only=True,
+                ),
+            )
         )
     else:
-        skills_vol = k8s_client.V1Volume(
-            name="skills",
-            host_path=k8s_client.V1HostPathVolumeSource(
-                path=SKILLS_HOST_PATH,
-                type="Directory",
-            ),
+        # hostPath mode: three-way layout
+        public_path = join_host_path(SKILLS_HOST_PATH, "public")
+        volumes.append(
+            k8s_client.V1Volume(
+                name="skills-public",
+                host_path=k8s_client.V1HostPathVolumeSource(
+                    path=public_path,
+                    type="Directory",
+                ),
+            )
         )
 
+        user_custom_path = join_host_path(
+            DEER_FLOW_HOST_BASE_DIR, "users", user_id, "skills", "custom",
+        )
+        volumes.append(
+            k8s_client.V1Volume(
+                name="skills-custom",
+                host_path=k8s_client.V1HostPathVolumeSource(
+                    path=user_custom_path,
+                    type="DirectoryOrCreate",
+                ),
+            )
+        )
+
+        if include_legacy_skills:
+            legacy_path = join_host_path(SKILLS_HOST_PATH, "custom")
+            volumes.append(
+                k8s_client.V1Volume(
+                    name="skills-legacy",
+                    host_path=k8s_client.V1HostPathVolumeSource(
+                        path=legacy_path,
+                        type="Directory",
+                    ),
+                )
+            )
+
+    # ── User-data volume ──────────────────────────────────────────────
+
     if USERDATA_PVC_NAME:
         userdata_vol = k8s_client.V1Volume(
             name="user-data",
@@ -286,13 +341,56 @@ def _build_volumes(thread_id: str) -> list[k8s_client.V1Volume]:
             ),
         )
 
-    return [skills_vol, userdata_vol]
+    volumes.append(userdata_vol)
+    return volumes
 
 
 def _build_volume_mounts(
-    thread_id: str, user_id: str = DEFAULT_USER_ID
+    thread_id: str,
+    user_id: str = DEFAULT_USER_ID,
+    *,
+    include_legacy_skills: bool = False,
 ) -> list[k8s_client.V1VolumeMount]:
-    """Build volume mount list, using subPath for PVC user-data."""
+    """Build volume mount list, mirroring three-way skills layout.
+
+    Skills are mounted to ``/mnt/skills/{public,custom,legacy}/`` so that
+    category-aware ``Skill.get_container_path()`` paths resolve correctly.
+    PVC mode falls back to a single ``/mnt/skills`` mount.
+    """
+    mounts: list[k8s_client.V1VolumeMount] = []
+
+    if SKILLS_PVC_NAME:
+        mounts.append(
+            k8s_client.V1VolumeMount(
+                name="skills",
+                mount_path="/mnt/skills",
+                read_only=True,
+            )
+        )
+    else:
+        mounts.extend(
+            [
+                k8s_client.V1VolumeMount(
+                    name="skills-public",
+                    mount_path="/mnt/skills/public",
+                    read_only=True,
+                ),
+                k8s_client.V1VolumeMount(
+                    name="skills-custom",
+                    mount_path="/mnt/skills/custom",
+                    read_only=True,
+                ),
+            ]
+        )
+        if include_legacy_skills:
+            mounts.append(
+                k8s_client.V1VolumeMount(
+                    name="skills-legacy",
+                    mount_path="/mnt/skills/legacy",
+                    read_only=True,
+                )
+            )
+
     userdata_mount = k8s_client.V1VolumeMount(
         name="user-data",
         mount_path="/mnt/user-data",
@@ -302,19 +400,17 @@ def _build_volume_mounts(
         userdata_mount.sub_path = (
             f"deer-flow/users/{user_id}/threads/{thread_id}/user-data"
         )
+    mounts.append(userdata_mount)
 
-    return [
-        k8s_client.V1VolumeMount(
-            name="skills",
-            mount_path="/mnt/skills",
-            read_only=True,
-        ),
-        userdata_mount,
-    ]
+    return mounts
 
 
 def _build_pod(
-    sandbox_id: str, thread_id: str, user_id: str = DEFAULT_USER_ID
+    sandbox_id: str,
+    thread_id: str,
+    user_id: str = DEFAULT_USER_ID,
+    *,
+    include_legacy_skills: bool = False,
 ) -> k8s_client.V1Pod:
     """Construct a Pod manifest for a single sandbox."""
     return k8s_client.V1Pod(
@@ -373,14 +469,22 @@ def _build_pod(
                             "ephemeral-storage": "500Mi",
                         },
                     ),
-                    volume_mounts=_build_volume_mounts(thread_id, user_id=user_id),
+                    volume_mounts=_build_volume_mounts(
+                        thread_id,
+                        user_id=user_id,
+                        include_legacy_skills=include_legacy_skills,
+                    ),
                     security_context=k8s_client.V1SecurityContext(
                         privileged=False,
                         allow_privilege_escalation=True,
                     ),
                 )
             ],
-            volumes=_build_volumes(thread_id),
+            volumes=_build_volumes(
+                thread_id,
+                user_id=user_id,
+                include_legacy_skills=include_legacy_skills,
+            ),
             restart_policy="Always",
         ),
     )
@@ -457,12 +561,14 @@ def create_sandbox(req: CreateSandboxRequest):
     sandbox_id = req.sandbox_id
     thread_id = req.thread_id
     user_id = req.user_id
+    include_legacy_skills = req.include_legacy_skills
 
     logger.info(
-        "Received request to create sandbox '%s' for thread '%s' user '%s'",
+        "Received request to create sandbox '%s' for thread '%s' user '%s' include_legacy_skills=%s",
         sandbox_id,
         thread_id,
         user_id,
+        include_legacy_skills,
     )
 
     # ── Fast path: sandbox already exists ────────────────────────────
@@ -477,7 +583,13 @@ def create_sandbox(req: CreateSandboxRequest):
     # ── Create Pod ───────────────────────────────────────────────────
     try:
         core_v1.create_namespaced_pod(
-            K8S_NAMESPACE, _build_pod(sandbox_id, thread_id, user_id=user_id)
+            K8S_NAMESPACE,
+            _build_pod(
+                sandbox_id,
+                thread_id,
+                user_id=user_id,
+                include_legacy_skills=include_legacy_skills,
+            ),
         )
         logger.info(f"Created Pod {_pod_name(sandbox_id)}")
     except ApiException as exc: