# HTTP Client Platform — Repository Adaptation Contract

**Design source:** `httpclient-superpowers-package/docs/superpowers/specs/2026-08-08-httpclient-platform-design.md`
**Plan source:** `httpclient-superpowers-package/docs/superpowers/plans/2026-08-08-httpclient-platform-implementation-plan.md`

The design package states its own adaptation rule:

> 실제 Backend Skeleton 저장소가 제공되지 않았으므로 package 경로와 Gradle 구조는 설계서의 명시적
> 구현 가정이다. 구현 전 저장소의 기존 convention과 root package에 맞춰 경로만 조정하고 공개 계약과
> 정책 의미론은 유지한다.

This file is the single record of *how* the design's assumed layout was mapped onto this repository.
Only paths, build DSL, and composition-root ownership changed. Public contracts, policy order, and
error semantics are implemented exactly as specified.

## 1. Why the module layout differs

The design assumes a greenfield library with 19 Gradle projects under `modules/httpclient/`.
This repository is a Clean Architecture template whose **fail-closed registry**
(`src/config/architecture/modules.json`, enforced by `src/settings.gradle` and
`verifyCleanArchitectureDependencies`) declares **exactly 19 leaf identities**. Creating 19 more
Gradle projects would violate HARD-STOP #5 in `AGENTS.md`.

Therefore the design's 19 library modules become **package boundaries inside the registered leaf**
`:adapter:outbound:httpclient`, with two exceptions driven by this repository's own rules:

| Design module | Repository home | Reason |
|---|---|---|
| `httpclient-spring-boot-starter` | `:app-bootstrap` (`dev.caskeleton.bootstrap.autoconfigure.httpclient`) | This repository's composition root owns wiring and canonical activation; an adapter leaf must not auto-configure itself. |
| `httpclient-testkit` | `:adapter:outbound:httpclient` `src/testkit/java/**/testkit` | The design forbids production modules depending on the testkit; a source set whose dependencies are declared only on the test configurations gives the same guarantee without a new Gradle project. It is its own source set rather than part of `test` because three lanes consume it — `test`, `httpClientPerformanceTest` and `jmh` — and reaching into `sourceSets.test.output` from `jmh` compiled under Gradle but could not be modelled by an IDE, which classifies a source set as test source only when a `Test` task runs its output and forbids main source from reading test source. `PlatformClasses` excludes the source set's output so the boundary rules keep meaning production classes. |

The package boundary is enforced by ArchUnit rules (`PublicApiArchitectureTest`,
`HttpClientModuleBoundaryTest`) that reproduce the design's module dependency table.

## 2. Package mapping

Root package: `io.backend.skeleton.httpclient` → `dev.caskeleton.adapter.outbound.httpclient`.

| Design module | Design package | Repository package |
|---|---|---|
| `httpclient-core-api` | `…httpclient.api` (+ `.body`, `.error`, `.operation`, `.result`) | `dev.caskeleton.adapter.outbound.httpclient.api` (+ same subpackages) |
| `httpclient-profile` | `…httpclient.profile` | `…outbound.httpclient.profile` |
| `httpclient-transport-spi` | `…httpclient.transport` | `…outbound.httpclient.transport` |
| `httpclient-transport-apache` | `…httpclient.apache` | `…outbound.httpclient.apache` |
| `httpclient-transport-jdk` | `…httpclient.jdk` | `…outbound.httpclient.jdk` |
| `httpclient-restclient` | `…httpclient.restclient` | `…outbound.httpclient.restclient` |
| `httpclient-resilience` | `…httpclient.resilience` | `…outbound.httpclient.resilience` |
| `httpclient-auth` | `…httpclient.auth` | `…outbound.httpclient.auth` |
| `httpclient-security` | `…httpclient.security` | `…outbound.httpclient.security` |
| `httpclient-observability` | `…httpclient.observation` | `…outbound.httpclient.observation` |
| `httpclient-transport-reactor-netty` | `…httpclient.reactor` | `…outbound.httpclient.reactor` |
| `httpclient-webclient` | `…httpclient.webclient` | `…outbound.httpclient.webclient` |
| `httpclient-service-client` | `…httpclient.service` | `…outbound.httpclient.service` |
| `httpclient-dynamic-target` | `…httpclient.dynamic` | `…outbound.httpclient.dynamic` |
| `httpclient-resttemplate-migration` | `…httpclient.migration` | `…outbound.httpclient.migration` |
| `httpclient-spring7-service-groups` | `…httpclient.spring7` | `…outbound.httpclient.spring7` |
| `httpclient-jetty-http3-experimental` | `…httpclient.http3` | `…outbound.httpclient.http3` |
| `httpclient-spring-boot-starter` | `…httpclient.autoconfigure` | `dev.caskeleton.bootstrap.autoconfigure.httpclient` |
| `httpclient-testkit` | `…httpclient.testkit` | `…outbound.httpclient.testkit` (`testkit` source set) |

## 3. Other deliberate substitutions

| Design assumption | Repository reality | Adaptation |
|---|---|---|
| Gradle Kotlin DSL, `build-logic` convention plugin | Groovy DSL, root `build.gradle` conventions, `LockMode.STRICT` dependency locking | Dependencies declared in `src/adapter/outbound/httpclient/build.gradle`; `gradle.lockfile` regenerated. |
| Spring Framework 6.2 baseline with 7.0 compatibility | Spring Boot 4.0.0 / Spring Framework 7.0 is the repository baseline | Common code targets the Spring 6.2 **API surface** (no 6.2-only or 7.0-only classes in common packages). The Spring 7 HTTP Service Group integration stays isolated in `…httpclient.spring7`, exactly as the design requires. |
| `settings.gradle.kts` module registration | Fail-closed registry | No registry change; leaf identity, gradle path, allowed dependencies unchanged. |
| Design §6.2 grades Apache HttpClient 5 as HTTP/2-capable | Spring's blocking factory drives Apache's **classic** client, which is HTTP/1.1 only; HTTP/2 lives in Apache's async client | `ApacheBlockingTransportProvider` declares HTTP/1.1 and rejects an HTTP/2 profile at startup. Blocking HTTP/2 is served by the JDK transport, measured by `NegotiatedProtocolContractTest`. |
| Design §28.1 names WireMock for stateful fixtures | WireMock's Jetty modules bind a different Jetty 12 ABI than the Boot-managed one this module already needs for HTTP/3, and fail at server start | `StatefulUpstream` provides path-keyed stateful responses on the existing fixture server; the WireMock dependency was removed rather than worked around with a shaded jar |
| Per-task `git commit` | `AGENTS.md`: commit policy is `human-only` | Implementation is delivered unstaged; commits are the human's action. This is the only plan step intentionally not executed, and it is recorded here. |
| `docs/httpclient/**`, `.github/workflows/httpclient-*.yml`, `scripts/verify-httpclient-docs.py` | Repository already owns `docs/` and `.github/workflows/` | Created at the same repository-relative paths. |

## 4. What is unchanged from the design

- H1 / H2 / H3 / H4 exposure rules and the forbidden native-engine signatures.
- `ExecutionEvidence`, `BodyReplayability`, `OperationIdempotency`, `AttemptStage`, `FailureCategory`.
- `HttpOperation`, `HttpCallResult`, `BodySource`, `ResponseType`, `BlockingStreamingResponse`.
- The complete stable exception hierarchy and `HttpFailureMetadata` redaction rules.
- Named Client Profile schema, startup validation codes, and operation override direction.
- Effective deadline formula, attempt budget, and streaming setup/idle split.
- Retry eligibility inputs, the ordered decision table, retry budget, and backoff rules.
- Circuit → Rate Limiter → Bulkhead attempt order and logical admission placement.
- OAuth2 cache key, single-flight refresh, and the 401 replay-at-most-once rule.
- TLS allow/forbid lists and permanent-failure classification.
- Dynamic Target canonicalization → all-answer DNS validation → pinning → redirect revalidation.
- Low-cardinality tag allowlist, forbidden labels, trace and logging rules.
- Runtime generation swap and drain semantics.