feat(tenancy): add Workspace multi-tenant foundation (#2353)

* Document multi-tenant workspace architecture

* Add OSS and commercial workspace boundaries

* docs: redesign multi-tenant workspace architecture

* feat(tenancy): implement workspace isolation

* docs(tenancy): record verification evidence

* docs(tenancy): revise single-instance SaaS topology

* docs(tenancy): refine architecture options

* docs: finalize cloud v2 multi-tenant decisions

* feat(tenancy): establish cloud isolation foundations

* feat(tenancy): harden shared cloud runtime boundaries

* docs(tenancy): record final isolation verification

* fix(tenancy): close isolation and permission gaps

* docs(tenancy): record final isolation verification

* feat(tenancy): connect cloud workspace control plane

* fix(build): install git for pinned SDK

* docs(cloud): update control plane verification

* chore: update multi-tenant SDK pin

* fix(cloud): skip legacy model sync during startup

* test(cloud): preserve minimal model manager fixtures

* fix(cloud): preserve authenticated account context

* fix(cloud): reuse authenticated account for user info

* feat(cloud): complete Workspace settings navigation

* test(web): cover Workspace dropdown menu

* feat(web): place workspace controls in sidebar

* refactor(web): streamline workspace controls

* style(web): format workspace layout test

* fix(cloud): surface runtime and workspace plan status

* fix(plugin): keep runtime identity stable across restarts

* fix(ui): widen and center workspace switcher

* fix(ui): hide roles from workspace switcher

* fix(ui): align workspace switcher with sidebar entries

* feat(workspace): add in-product collaboration and direct Cloud launch

* style: format collaboration changes

* fix(workspace): bind collaboration APIs to tenant UoW

* fix(cloud): preserve Core-owned collaboration state

* test(cloud): require Space identity for invite registration

* feat(cloud): complete secure invitation experience

* style(web): format invitation flows

* fix(cloud): recover box runtime without unscoped skill reload

* feat(oss): enforce invitation account and owner billing flows

* style: format OSS account service

* test(oss): cover invitation logout handoff

* fix(oss): resolve workspace owner in scoped session

* feat(cloud): harden multi-tenant runtime resources

* fix(cloud): bound runtime restart storms

* fix(cloud): eliminate periodic runtime CPU spikes

* fix(cloud): enforce instance capacity ceilings

* fix(cloud): scope public login capability discovery

* fix(cloud): bound tenant maintenance and monitoring work

* fix(runtime): bound tenant resource amplification

* fix(deps): pin green multi-tenant plugin SDK

* fix(cloud): handle unavailable skill capability

* fix(security): require authentication for image file endpoint (H-2)

- Changed /api/v1/files/image from AuthType.NONE to USER_TOKEN_OR_API_KEY
- Added Permission.RESOURCE_VIEW requirement
- Prevents unauthenticated cross-tenant file access via leaked keys
- Fixes HIGH severity finding from multi-tenant security review

docs: add comprehensive database migration guide
- Complete migration steps for OSS → multi-tenant
- Backup, execution, verification procedures
- Rollback scenarios and recovery plans
- Performance tuning recommendations

* test: add comprehensive cross-tenant isolation tests

Added 7 critical test scenarios for multi-tenant boundaries:
- Cross-tenant bot access prevention
- Viewer role read-only enforcement
- Removed member immediate access revocation
- Model provider credential isolation
- WebSocket message isolation
- Invitation token workspace scoping
- Multi-workspace context validation

These tests address P0-2 coverage gaps for:
- workspaces.py (membership & invitation flows)
- user.py (authentication & authorization)
- websocket_chat.py (real-time isolation)
- plugins.py (resource access control)

docs: finalize database migration guide

* fix(security): resolve M-1, M-2, M-3 security findings

M-1: WebSocket authorization TOCTOU race (FIXED)
- Changed _revalidate_websocket_authorization to return RequestContext
- Ensures validated context is used immediately without race window
- Prevents removed members from sending messages during revalidation gap

M-2: Model Manager cache workspace isolation (VERIFIED)
- Confirmed _CacheKey already uses 4-tuple: (instance, workspace, generation, resource)
- Cache is properly scoped per workspace, no cross-tenant leakage possible
- No code change needed, documented as working correctly

M-3: Invitation lock workspace scoping (FIXED)
- Changed lock key from token_digest to workspace_uuid:token_digest
- Prevents DoS where attacker locks token in Workspace A to block Workspace B
- Locks now isolated per workspace

All MEDIUM severity findings from security review now resolved.

* fix(cloud): unblock tenant CI and enforce knowledge quotas

* fix(tenancy): scope rerank model sync

---------

Co-authored-by: dadachann <185672915+dadachann@users.noreply.github.com>

tests/integration/api/test_skills_entitlements.py

@@ -0,0 +1,79 @@
+"""Skills API behavior when a workspace plan has no managed sandbox."""
+
+from __future__ import annotations
+
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, Mock
+
+import pytest
+import quart
+
+from langbot.pkg.api.http.controller.groups.skills import SkillsRouterGroup
+from langbot.pkg.cloud.entitlements import (
+    EntitlementFeatureUnavailableError,
+    EntitlementUnavailableError,
+)
+
+pytestmark = pytest.mark.integration
+WORKSPACE_UUID = '11111111-1111-4111-8111-111111111111'
+
+
+@pytest.fixture
+async def skills_api():
+    account = SimpleNamespace(uuid='owner-account', user='owner@example.com')
+    access = SimpleNamespace(
+        workspace=SimpleNamespace(uuid=WORKSPACE_UUID),
+        membership=SimpleNamespace(uuid='member-owner', role='owner', projection_revision=1),
+        execution=SimpleNamespace(instance_uuid='instance-a', placement_generation=1),
+    )
+    application = Mock()
+    application.deployment = SimpleNamespace(multi_workspace_enabled=False)
+    application.persistence_mgr = SimpleNamespace(tenant_uow=None)
+    application.user_service.get_authenticated_account = AsyncMock(return_value=account)
+    application.workspace_collaboration_service.resolve_account_workspace = AsyncMock(return_value=access)
+    application.skill_service.list_skills = AsyncMock(
+        side_effect=EntitlementFeatureUnavailableError(
+            'managed_sandbox',
+            entitlement_revision=1,
+        )
+    )
+
+    quart_app = quart.Quart(__name__)
+    router = SkillsRouterGroup(application, quart_app)
+    await router.initialize()
+    return application, quart_app.test_client()
+
+
+@pytest.mark.asyncio
+async def test_list_skills_is_empty_when_plan_has_no_managed_sandbox(skills_api):
+    application, client = skills_api
+    response = await client.get(
+        '/api/v1/skills',
+        headers={
+            'Authorization': 'Bearer owner-token',
+            'X-Workspace-Id': WORKSPACE_UUID,
+        },
+    )
+
+    assert response.status_code == 200
+    payload = await response.get_json()
+    assert payload['data'] == {'skills': []}
+    application.skill_service.list_skills.assert_awaited_once()
+
+
+@pytest.mark.asyncio
+async def test_list_skills_does_not_hide_other_entitlement_failures(skills_api):
+    application, client = skills_api
+    application.skill_service.list_skills.side_effect = EntitlementUnavailableError(
+        'Workspace entitlement revision rolled back'
+    )
+
+    response = await client.get(
+        '/api/v1/skills',
+        headers={
+            'Authorization': 'Bearer owner-token',
+            'X-Workspace-Id': WORKSPACE_UUID,
+        },
+    )
+
+    assert response.status_code == 500