patterncatalyst · Oct 13, 2026 · Oct 13, 2026 · Oct 13, 2026
diff --git a/CLAUDE.md b/CLAUDE.md
@@ -184,6 +184,26 @@ Do not use `gh cache delete --all`: it also removes the entries the current poli
     Drogon's `LOG_*`; services without Drogon use spdlog. `std::cout`/`std::cerr` only for CLI and test output.
     Adding a Conan dependency to an existing lock uses `conan lock create --lockfile=conan.lock
     --lockfile-partial`, so the other pins stay.
+- **Resilience and gRPC through libraries (S14):**
+  - Breaker, retry and bulkhead: Spring Boot uses Resilience4j (`resilience4j-spring-boot4` 2.4.0 with
+    `spring-boot-starter-aspectj`; annotations on a separate bean, limits in properties; per-tenant
+    bulkheads from the `BulkheadRegistry`); Quarkus uses SmallRye Fault Tolerance (annotations on a CDI bean;
+    per-tenant bulkheads with the programmatic `Guard`); .NET uses Polly v8 pipelines through
+    Microsoft.Extensions.Http.Resilience 10.10.0 with Polly.Extensions and Polly.RateLimiting pinned to 8.8.0
+    (the package only sets a floor), and System.Threading.RateLimiting's `PartitionedRateLimiter` for
+    per-tenant limits; Python uses tenacity (retry) and pybreaker (breaker, around awaited calls with
+    `calling()`), bulkheads on `asyncio.Semaphore`; Go keeps sony/gobreaker and cenkalti/backoff and uses
+    `golang.org/x/sync/semaphore` for bulkheads. C++ has no maintained library on ConanCenter, so its breaker
+    and bulkhead stay in the service, in Drogon coroutine handlers that never block an event-loop thread.
+  - Contract: a full bulkhead refuses at once with 429 (never queues); `/breaker-state` is `{name, state}`
+    with `closed|open|half-open`, plus whatever metrics the library exposes. Shared breaker settings:
+    5 failures open it, 10 s open, 2 trial successes close it (Polly lets one trial through).
+  - Spring gRPC 1.1.1 (managed by Boot 4.1.1): servers are `@GrpcService` beans hosted by
+    `spring-boot-starter-grpc-server` on `spring.grpc.server.port` (graceful shutdown, standard health and
+    reflection services); callers take channels from `GrpcChannelFactory`
+    (`spring.grpc.client.channel.<name>.target`). Never `ServerBuilder` or `ManagedChannelBuilder` by hand.
+    The protobuf plugin stays xolstice 0.6.1: the Boot-managed `io.github.ascopes` plugin fails under the
+    UBI image's packaged Maven. .NET callers use the gRPC client factory (`AddGrpcClient`).
 
 ## House test tools (prefer these; don't introduce alternatives)
 

diff --git a/_docs/01-cloud-native-principles.md b/_docs/01-cloud-native-principles.md
@@ -302,5 +302,5 @@ The code is in [`examples/01-cloud-native-principles/`](https://github.com/patte
 and runs it; its `README.md` covers what it does and how to drive it.
 
 ---
-*Verification status: verified — [`examples/01-cloud-native-principles/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/01-cloud-native-principles/) passes 13/13 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/01-cloud-native-principles/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/01-cloud-native-principles/) passes 13/13 checks in each of the six languages on Docker Engine (2026-10-13)
 (health probes, config from environment, CRUD, readiness flip on dependency failure).*
diff --git a/_docs/02-communications.md b/_docs/02-communications.md
@@ -413,5 +413,5 @@ The code is in [`examples/02-communications/`](https://github.com/patterncatalys
 it; its `README.md` covers what it does and how to drive it.
 
 ---
-*Verification status: verified — [`examples/02-communications/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/02-communications/) passes 10/10 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/02-communications/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/02-communications/) passes 10/10 checks in each of the six languages on Docker Engine (2026-10-13)
 (REST create and validation (201, 422), cursor pagination, order confirmation and rejection driven by the gRPC stock reservation, a GraphQL orders query, and the order.placed Kafka topic).*
diff --git a/_docs/03-composition.md b/_docs/03-composition.md
@@ -274,5 +274,5 @@ The code is in [`examples/03-composition/`](https://github.com/patterncatalyst/c
 its `README.md` covers what it does and how to drive it.
 
 ---
-*Verification status: verified — [`examples/03-composition/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/03-composition/) passes 8/8 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/03-composition/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/03-composition/) passes 8/8 checks in each of the six languages on Docker Engine (2026-10-13)
 (GraphQL gateway fan-out to the REST order API and the gRPC stock service, selective stock-field resolution, DataLoader batching of stock lookups into one gRPC call, single-order lookup).*
diff --git a/_docs/04-data.md b/_docs/04-data.md
@@ -331,5 +331,5 @@ The code is in [`examples/04-data/`](https://github.com/patterncatalyst/cloud-na
 `README.md` covers what it does and how to drive it.
 
 ---
-*Verification status: verified — [`examples/04-data/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/04-data/) passes 8/8 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/04-data/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/04-data/) passes 8/8 checks in each of the six languages on Docker Engine (2026-10-13)
 (transactional write of order and outbox row, Debezium outbox connector running, relay of the outbox event to the order.placed Kafka topic with its payload).*
diff --git a/_docs/05-event-driven.md b/_docs/05-event-driven.md
@@ -1297,5 +1297,5 @@ it; its `README.md` covers what it does and how to drive it. The same example, w
 the Strimzi operator, also runs on a Kubernetes cluster; Appendix R covers that deployment on minikube and Appendix S covers OpenShift Local.
 
 ---
-*Verification status: verified — [`examples/05-event-driven/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/05-event-driven/) passes 10/10 checks in each of the six languages on Docker Engine (2026-10-12) and on minikube (2026-10-11, Appendix R), and 10/10 in five languages on OpenShift Local 4.22.14 (2026-10-11, Appendix S)
+*Verification status: verified — [`examples/05-event-driven/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/05-event-driven/) passes 10/10 checks in each of the six languages on Docker Engine (2026-10-13) and on minikube (2026-10-11, Appendix R), and 10/10 in five languages on OpenShift Local 4.22.14 (2026-10-11, Appendix S)
 (event publication to order.placed, fan-out to two independent consumer groups (shipping and notification), and idempotent consumers under a redelivered duplicate event).*
diff --git a/_docs/06-stream-processing.md b/_docs/06-stream-processing.md
@@ -339,5 +339,5 @@ The code is in [`examples/06-stream-processing/`](https://github.com/patterncata
 runs it; its `README.md` covers what it does and how to drive it.
 
 ---
-*Verification status: verified — [`examples/06-stream-processing/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/06-stream-processing/) passes 11/11 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/06-stream-processing/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/06-stream-processing/) passes 11/11 checks in each of the six languages on Docker Engine (2026-10-13)
 (per-merchant revenue aggregation onto a derived Kafka topic, the stream-processor consumer group, consumer lag that builds while the processor is paused and drains on resume, and the burst appearing in the revenue stream).*
diff --git a/_docs/09-api-registry.md b/_docs/09-api-registry.md
@@ -340,5 +340,5 @@ breaking change failing the build and the additive change passing it is the enti
 point of the registry.
 
 ---
-*Verification status: verified — [`examples/09-api-registry/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/09-api-registry/) passes 8/8 checks on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/09-api-registry/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/09-api-registry/) passes 8/8 checks on Docker Engine (2026-10-13)
 (schema registration, BACKWARD compatibility rule, rejection of a breaking change with 400, acceptance of an additive change, versioned retrieval).*
diff --git a/_docs/11-observability.md b/_docs/11-observability.md
@@ -443,5 +443,5 @@ the rest. Seeing one request as one waterfall is the moment observability stops
 being three disconnected tools.
 
 ---
-*Verification status: verified — [`examples/11-observability/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/11-observability/) passes 10/10 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/11-observability/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/11-observability/) passes 10/10 checks in each of the six languages on Docker Engine (2026-10-13)
 (trace propagation, metric export, structured log correlation, LGTM stack integration).*
diff --git a/_docs/12-security.md b/_docs/12-security.md
@@ -753,5 +753,5 @@ step pre-merge. A request without identity being refused, and an unsigned image
 being blocked twice, is the layered model working.
 
 ---
-*Verification status: verified — [`examples/12-security/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/12-security/) passes 16/16 checks in each of the six languages on Docker Engine (2026-10-12)
-(sidecar identity trust (403 without X-Forwarded-Client-Cert, health-check bypass), propagation of the JWT subject claim, valet-key mint, verify and tamper rejection, per-tenant bulkhead state, and conftest Rego policy evaluation of a good and a bad manifest. JWT signature validation, RBAC enforcement and rate limiting are not covered).*
+*Verification status: verified — [`examples/12-security/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/12-security/) passes 18/18 checks in each of the six languages on Docker Engine (2026-10-13)
+(sidecar identity trust (403 without X-Forwarded-Client-Cert, health-check bypass), propagation of the JWT subject claim, valet-key mint, verify and tamper rejection, per-tenant bulkhead state, a full tenant pool refusing the overflow with 429 while another tenant is still served, and conftest Rego policy evaluation of a good and a bad manifest. JWT signature validation, RBAC enforcement and rate limiting are not covered).*
diff --git a/_docs/16-appendix-c-websockets.md b/_docs/16-appendix-c-websockets.md
@@ -555,5 +555,5 @@ Deployment down by one and confirm the dropped clients reconnect with backoff an
 resume from their last sequence rather than losing the stream.
 
 ---
-*Verification status: verified — [`examples/16-websockets/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/16-websockets/) passes 6/6 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/16-websockets/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/16-websockets/) passes 6/6 checks in each of the six languages on Docker Engine (2026-10-13)
 (WebSocket connect, cross-pod delivery and broadcast over the Redis pub/sub backplane, monotonic sequence numbers).*
diff --git a/_docs/17-appendix-d-sagas.md b/_docs/17-appendix-d-sagas.md
@@ -328,5 +328,5 @@ inverses over only the completed steps, plus a clean resume, shows the saga
 works.
 
 ---
-*Verification status: verified — [`examples/17-sagas/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/17-sagas/) passes 11/11 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/17-sagas/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/17-sagas/) passes 11/11 checks in each of the six languages on Docker Engine (2026-10-13)
 (orchestrated saga happy path, compensation in reverse order on failure, skipped compensation for steps that never completed, resume of a RUNNING saga after an orchestrator restart).*
diff --git a/_docs/18-appendix-e-errors.md b/_docs/18-appendix-e-errors.md
@@ -853,5 +853,5 @@ load. A flat downstream-call line under rising pressure is the retry budget and
 doing their job; a climbing one means a control is missing.
 
 ---
-*Verification status: verified — [`examples/18-errors/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/18-errors/) passes 13/13 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/18-errors/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/18-errors/) passes 13/13 checks in each of the six languages on Docker Engine (2026-10-13)
 (RFC 9457 problem details over REST for validation (422), stock conflict (409) and upstream unavailable (503), with error codes, traceId, retryable and retryAfter fields).*
diff --git a/_docs/19-appendix-f-ddd-hexagonal.md b/_docs/19-appendix-f-ddd-hexagonal.md
@@ -354,5 +354,5 @@ new adapter file appears. A clean domain import list plus a no-domain-change dif
 you bolt on a protocol is hexagonal architecture holding.
 
 ---
-*Verification status: verified — [`examples/19-ddd-hexagonal/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/19-ddd-hexagonal/) passes 17/17 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/19-ddd-hexagonal/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/19-ddd-hexagonal/) passes 17/17 checks in each of the six languages on Docker Engine (2026-10-13)
 (source scans proving the domain layer imports no framework or persistence types, REST and CLI adapters driving the same use case, input validation, OrderPlaced event emission).*
diff --git a/_docs/21-appendix-h-shutdown.md b/_docs/21-appendix-h-shutdown.md
@@ -331,5 +331,5 @@ A clean rollout under live load, not a green integration test, is evidence that
 works.
 
 ---
-*Verification status: verified — [`examples/21-graceful-shutdown/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/21-graceful-shutdown/) passes 17/17 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/21-graceful-shutdown/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/21-graceful-shutdown/) passes 17/17 checks in each of the six languages on Docker Engine (2026-10-13)
 (one SIGTERM, readiness flip to 503, the drain log lines, exit code 0 inside the grace period, a `docker stop` timing check, restart recovery, and orders persisting across the restart. In-flight request draining is not checked by the script).*
diff --git a/_docs/22-appendix-i-l7-routing.md b/_docs/22-appendix-i-l7-routing.md
@@ -681,5 +681,5 @@ track the config and a ruleset that can move routing without a code change are t
 this appendix working.
 
 ---
-*Verification status: verified — [`examples/22-l7-routing/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/22-l7-routing/) passes 15/15 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/22-l7-routing/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/22-l7-routing/) passes 15/15 checks in each of the six languages on Docker Engine (2026-10-13)
 (Envoy weighted traffic split, header-based routing override, in-app rule-driven routing, and changing routing rules without a redeploy. Canary promotion and circuit breaking are not covered).*
diff --git a/_docs/24-appendix-k-monolith-to-microservices.md b/_docs/24-appendix-k-monolith-to-microservices.md
@@ -586,5 +586,5 @@ write *and* that an `order.placed` event landed on Kafka. Same client-visible AP
 underneath, legacy untouched — that is the decorator doing its job.
 
 ---
-*Verification status: verified — [`examples/24-monolith-to-microservices/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/24-monolith-to-microservices/) passes 19/19 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/24-monolith-to-microservices/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/24-monolith-to-microservices/) passes 19/19 checks in each of the six languages on Docker Engine (2026-10-13)
 (strangler fig router with per-tenant routing, reversible cutover, a decorating collaborator adding caching and Kafka event emission, and an untouched legacy service).*
diff --git a/_docs/25-appendix-l-caching.md b/_docs/25-appendix-l-caching.md
@@ -1225,5 +1225,5 @@ the new value with no DB round trip; for write-around, write then read and confi
 miss (the DB log shows the `SELECT`) while the second is a hit.
 
 ---
-*Verification status: verified — [`examples/25-caching/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/25-caching/) passes 29/29 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/25-caching/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/25-caching/) passes 29/29 checks in each of the six languages on Docker Engine (2026-10-13)
 (cache-aside with invalidation on update, read-through, write-through, write-around, write-back with 202 and a flush retry across a Postgres outage, refresh-ahead, hot-set tracking, and degradation with Redis stopped and restarted).*
diff --git a/_docs/26-appendix-m-failure-modes.md b/_docs/26-appendix-m-failure-modes.md
@@ -772,5 +772,5 @@ This appendix touches difficult operational territory; if you are diagnosing a l
 Google SRE cascading-failures chapter is the fastest way to a shared vocabulary with your team.
 
 ---
-*Verification status: verified — [`examples/26-failure-modes/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/26-failure-modes/) passes 20/20 checks in each of the six languages on Docker Engine (2026-10-12)
-(timeout, retry exhaustion, circuit breaker closed, open and recovered with fallback, deadline-budget propagation, bulkhead limit).*
+*Verification status: verified — [`examples/26-failure-modes/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/26-failure-modes/) passes 22/22 checks in each of the six languages on Docker Engine (2026-10-13)
+(timeout, retry exhaustion, circuit breaker closed, open and recovered with fallback, deadline-budget propagation, bulkhead limit, a full bulkhead refusing the overflow with 429 and admitting again).*
diff --git a/_docs/27-appendix-n-feature-flags.md b/_docs/27-appendix-n-feature-flags.md
@@ -417,5 +417,5 @@ lookup is on a critical path without a default, which is the one feature-flag mi
 ship.
 
 ---
-*Verification status: verified — [`examples/27-feature-flags/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/27-feature-flags/) passes 14/14 checks in each of the six languages on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/27-feature-flags/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/27-feature-flags/) passes 14/14 checks in each of the six languages on Docker Engine (2026-10-13)
 (plan-based targeting rules, sticky assignment and percentage rollout, kill switch, simple boolean flag, flag listing, and safe defaults while flagd is down).*
diff --git a/_docs/28-appendix-o-newman.md b/_docs/28-appendix-o-newman.md
@@ -276,5 +276,5 @@ service and fails against one that wrongly accepts it. A suite that goes red on
 break, and only then, is the whole value of this appendix.
 
 ---
-*Verification status: verified — [`examples/28-newman/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/28-newman/) passes 11/11 checks on Docker Engine (2026-10-12)
+*Verification status: verified — [`examples/28-newman/`](https://github.com/patterncatalyst/cloud-native-design-patterns/tree/main/examples/28-newman/) passes 11/11 checks on Docker Engine (2026-10-13)
 (a Newman collection run with status-code and state assertions (201, 422, 404, 204, cancel) and JUnit XML export).*