Add security architecture pattern infospace

infospaces/patterns-of-it-securita-architecture/artifacts/entities/pattern-tenant-isolation.md

@@ -0,0 +1,81 @@
+# Pattern: Tenant Isolation
+
+Status: draft
+Readiness target: RL3 production
+Primary owners: NetKingdom, Railiance platform, product repos
+
+## Problem
+
+Multi-tenant systems fail dangerously when tenant identity, runtime,
+data, control-plane authority, or background jobs can cross boundaries
+implicitly.
+
+## Context
+
+Use this pattern for SaaS products, shared clusters, shared databases,
+object storage, platform services, admin tools, and asynchronous jobs.
+
+## Forces
+
+- Shared infrastructure improves efficiency.
+- Tenants need strong data and authorization boundaries.
+- Isolation may be implemented at namespace, cluster, cell, database,
+  key, policy, or API layers.
+- Product teams need a clear contract for carrying tenant context.
+
+## Solution
+
+Make tenant context an explicit security boundary across identity,
+authorization, runtime, data, audit, and operations. Choose isolation
+strength per risk: namespace, cluster, cell, data partition, or isolated
+data plane.
+
+## Implementation Sketch
+
+1. Define tenant id format and trust source.
+2. Require tenant context in request and job envelopes.
+3. Enforce tenant scope in flex-auth decisions.
+4. Partition data and object storage by tenant.
+5. Apply runtime and network boundaries for tenant workloads.
+6. Record tenant id in audit and detection events.
+
+## Failure Modes
+
+| Failure | Mitigation |
+| --- | --- |
+| Tenant id accepted from untrusted input | derive from trusted identity/session claims |
+| Background jobs lose tenant context | require job envelope tenant binding |
+| Shared database queries miss tenant filter | add query guards and tests |
+| Control plane can mutate tenant resources globally | add guardrails and review flows |
+
+## Related Capabilities
+
+- Tenant isolation.
+- Authorization and access control.
+- Data protection and privacy.
+- Observability, detection, and audit.
+
+## Maturity
+
+Draft. The capability is central and well described; individual products
+need concrete verification patterns.
+
+## Verification
+
+- Cross-tenant access tests fail for APIs, jobs, storage, and admin
+  paths.
+- Tenant id is present in identity, authorization, and audit records.
+- Data access includes tenant partition enforcement.
+- Control-plane operations are tenant scoped unless explicitly platform
+  scoped.
+
+## Research Basis
+
+Seeded by tenant identity boundary, namespace-per-tenant,
+cluster-per-tenant, cell-based architecture, isolated data plane,
+tenant context propagation, and tenant data partitioning.
+
+## References
+
+- Initial exploration: Tenant isolation capability group.
+- Initial exploration: Tenant isolation patterns.