diff --git a/tests/api/drives_membership.hurl b/tests/api/drives_membership.hurl
new file mode 100644
index 00000000..97587f88
--- /dev/null
+++ b/tests/api/drives_membership.hurl
@@ -0,0 +1,218 @@
+# =============================================================
+# OxiCloud — D2 drive membership API + delegation + caller_role
+# =============================================================
+# Verifies the D2 membership surface on personal drives (the only
+# drive kind today — shared-drive positive cases land alongside D3's
+# create endpoint):
+#
+#   1. `GET /api/drives` exposes `caller_role` on every row.
+#   2. `GET /api/drives/{id}/members` lists role grants on a drive
+#      (one Owner row for the lifecycle-hook-provisioned default).
+#   3. Personal-drive guard refuses every membership mutation
+#      (POST / PATCH / DELETE on `/api/drives/{id}/members*`) with
+#      405 — personal drives are single-user single-owner.
+#   4. The same guard fires on the generic `/api/grants` write paths
+#      (POST / PUT / DELETE) when `resource.type='drive'` and the
+#      drive is personal — verifies the `DriveManagementService`
+#      delegation that closes the bypass.
+#   5. Drive grants surface in `GET /api/grants/incoming/resources`
+#      with `resource_types=drive` filter (previously hard-skipped).
+#   6. Anti-enum: an unrelated user gets the same `404` for a drive
+#      they can't read, whether or not it exists.
+#
+# Self-contained: provisions its own users so it can run after
+# drives_foundation without aliasing state.
+# =============================================================
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 1 — admin login
+# ─────────────────────────────────────────────────────────────
+POST {{base_url}}/api/auth/login
+Content-Type: application/json
+{ "username": "{{username}}", "password": "{{password}}" }
+
+HTTP 200
+[Captures]
+admin_token: jsonpath "$.access_token"
+admin_user_id: jsonpath "$.user.id"
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 2 — Admin's GET /api/drives now includes `caller_role`.
+#          Personal-drive owner role is seeded by
+#          PersonalDriveLifecycleHook on user creation.
+# ─────────────────────────────────────────────────────────────
+GET {{base_url}}/api/drives
+Authorization: Bearer {{admin_token}}
+
+HTTP 200
+[Asserts]
+jsonpath "$[0].kind"             == "personal"
+jsonpath "$[0].default_for_user" == "{{admin_user_id}}"
+jsonpath "$[0].caller_role"      == "owner"
+
+[Captures]
+admin_drive_id: jsonpath "$[0].id"
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 3 — GET /api/drives/{id}/members returns the lifecycle-
+#          seeded Owner row and only that.
+# ─────────────────────────────────────────────────────────────
+GET {{base_url}}/api/drives/{{admin_drive_id}}/members
+Authorization: Bearer {{admin_token}}
+
+HTTP 200
+[Asserts]
+jsonpath "$"                       count == 1
+jsonpath "$[0].subject.type"       == "user"
+jsonpath "$[0].subject.id"         == "{{admin_user_id}}"
+jsonpath "$[0].resource.type"      == "drive"
+jsonpath "$[0].resource.id"        == "{{admin_drive_id}}"
+jsonpath "$[0].role"               == "owner"
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 4 — Create a fresh user (mbr_alice) so we have a second
+#          subject the personal-drive guard can refuse on.
+# ─────────────────────────────────────────────────────────────
+POST {{base_url}}/api/admin/users
+Authorization: Bearer {{admin_token}}
+Content-Type: application/json
+{ "username": "mbr_alice", "password": "MbrAlicePassword1!", "email": "mbr_alice@example.com", "role": "user" }
+
+HTTP 201
+[Captures]
+alice_user_id: jsonpath "$.id"
+
+POST {{base_url}}/api/auth/login
+Content-Type: application/json
+{ "username": "mbr_alice", "password": "MbrAlicePassword1!" }
+
+HTTP 200
+[Captures]
+alice_token: jsonpath "$.access_token"
+
+# Alice's GET /api/drives surfaces her own default with caller_role=owner.
+GET {{base_url}}/api/drives
+Authorization: Bearer {{alice_token}}
+
+HTTP 200
+[Asserts]
+jsonpath "$"                     count == 1
+jsonpath "$[0].caller_role"      == "owner"
+jsonpath "$[0].default_for_user" == "{{alice_user_id}}"
+
+[Captures]
+alice_drive_id: jsonpath "$[0].id"
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 5 — Personal-drive guard via the dedicated endpoint:
+#          POST /api/drives/{id}/members refuses with 405.
+# ─────────────────────────────────────────────────────────────
+POST {{base_url}}/api/drives/{{admin_drive_id}}/members
+Authorization: Bearer {{admin_token}}
+Content-Type: application/json
+{
+  "subject": { "type": "user", "id": "{{alice_user_id}}" },
+  "role": "editor"
+}
+
+HTTP 405
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 6 — PATCH on a personal drive's members → 405 (even for
+#          the owner row itself; personal drives' membership
+#          is structurally immutable).
+# ─────────────────────────────────────────────────────────────
+PATCH {{base_url}}/api/drives/{{admin_drive_id}}/members/user/{{admin_user_id}}
+Authorization: Bearer {{admin_token}}
+Content-Type: application/json
+{ "role": "editor" }
+
+HTTP 405
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 7 — DELETE on a personal drive's owner → 405. (Verifies
+#          the guard fires BEFORE the last-owner check; the order
+#          matters for the right error.)
+# ─────────────────────────────────────────────────────────────
+DELETE {{base_url}}/api/drives/{{admin_drive_id}}/members/user/{{admin_user_id}}
+Authorization: Bearer {{admin_token}}
+
+HTTP 405
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 8 — Generic /api/grants delegation. POST /api/grants with
+#          resource.type='drive' on a personal drive must hit the
+#          same guard, otherwise the membership rules are bypassable.
+# ─────────────────────────────────────────────────────────────
+POST {{base_url}}/api/grants
+Authorization: Bearer {{admin_token}}
+Content-Type: application/json
+{
+  "resource": { "type": "drive", "id": "{{admin_drive_id}}" },
+  "subject":  { "type": "user",  "id": "{{alice_user_id}}" },
+  "role": "editor"
+}
+
+HTTP 405
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 9 — PUT /api/grants/role (silent admin update) on a drive
+#          resource — also delegated. Same guard fires.
+# ─────────────────────────────────────────────────────────────
+PUT {{base_url}}/api/grants/role
+Authorization: Bearer {{admin_token}}
+Content-Type: application/json
+{
+  "resource": { "type": "drive", "id": "{{admin_drive_id}}" },
+  "subject":  { "type": "user",  "id": "{{admin_user_id}}" },
+  "role": "editor"
+}
+
+HTTP 405
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 10 — Drive grants in /api/grants/incoming/resources.
+#           Default UI calls pass `resource_types=file,folder` so
+#           drives don't appear; explicit `resource_types=drive`
+#           must surface the admin's Owner grant on their own drive.
+# ─────────────────────────────────────────────────────────────
+GET {{base_url}}/api/grants/incoming/resources?resource_types=drive
+Authorization: Bearer {{admin_token}}
+
+HTTP 200
+[Asserts]
+jsonpath "$.items"                count >= 1
+jsonpath "$.items[0].resource_type" == "drive"
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 11 — Anti-enum: Alice queries the members of admin's
+#           personal drive. She has no Read on it → 404, same
+#           shape as "drive doesn't exist". Operators see the
+#           real reason in the audit log; she sees nothing.
+# ─────────────────────────────────────────────────────────────
+GET {{base_url}}/api/drives/{{admin_drive_id}}/members
+Authorization: Bearer {{alice_token}}
+
+HTTP 404
+
+
+# ─────────────────────────────────────────────────────────────
+# Step 12 — The same anti-enum shape for a UUID that doesn't
+#           exist at all. Indistinguishable from step 11 to the
+#           caller — the canonical no-leak response.
+# ─────────────────────────────────────────────────────────────
+GET {{base_url}}/api/drives/00000000-0000-0000-0000-000000000000/members
+Authorization: Bearer {{alice_token}}
+
+HTTP 404
diff --git a/tests/api/run.sh b/tests/api/run.sh
index ebe7450f..d0639366 100755
--- a/tests/api/run.sh
+++ b/tests/api/run.sh
@@ -152,6 +152,7 @@ hurl --variables-file "$API_DIR/test.env" --file-root "$REPO_ROOT/tests" --test
   "$API_DIR/groups_effective_members.hurl" \
   "$API_DIR/grants_nested_groups.hurl" \
   "$API_DIR/drives_foundation.hurl" \
+  "$API_DIR/drives_membership.hurl" \
   "$API_DIR/external_users.hurl" \
   "$API_DIR/search_basic.hurl" \
   "$API_DIR/nc_second_user_setup.hurl" \