feat: pydantic as an optional extra (0.3.0)

README.md

@@ -7,26 +7,25 @@
 
 **Async HTTP client framework for Python.**
 
-`httpware` is a typed, async HTTP client library with a protocol-based seam so the transport is swappable (`httpx2` ships as the default). Middleware composes via an onion model. Pydantic and msgspec response decoding ship out of the box. `RecordedTransport` replaces `respx` for transport-level tests.
+`httpware` is a thin opinionated wrapper around `httpx2`. It re-exports `httpx2.Request`/`httpx2.Response`, adds a middleware chain composed at client construction, supports opt-in typed response decoding (pydantic and msgspec are both extras), and raises a status-keyed exception tree automatically on 4xx/5xx.
 
-> **Status:** Pre-1.0 (0.1.0 alpha). Public API is subject to change between minor releases until v1.0. Resilience middleware (retry / timeout / bulkhead), streaming, and observability are not yet shipped.
+> **Status:** Pre-1.0 (0.3.0). Public API is subject to change between minor releases until v1.0. Resilience middleware (retry / timeout / bulkhead), streaming, and observability are not yet shipped.
 
 ## Install
 
 ```bash
-pip install httpware
+pip install httpware                # core only — no decoder
+pip install httpware[pydantic]      # + PydanticDecoder (the default-decoder path)
+pip install httpware[msgspec]       # + MsgspecDecoder
+pip install httpware[all]           # everything declared above (pydantic, msgspec, otel)
 ```
 
-Optional extras:
-
-```bash
-pip install httpware[msgspec]    # MsgspecDecoder
-```
-
-(`otel`, `niquests`, and `all` extras are declared; integrations have not shipped yet.)
+`AsyncClient()` with no `decoder=` argument defaults to constructing a `PydanticDecoder`; that path requires the `pydantic` extra and raises `ImportError` at `AsyncClient.__init__` if it is missing. The `otel` extra is declared but the OpenTelemetry middleware (Epic 5) has not shipped yet.
 
 ## Quickstart
 
+> Requires: `pip install httpware[pydantic]`
+
 ```python
 from httpware import AsyncClient
 from pydantic import BaseModel

planning/engineering.md

@@ -4,7 +4,7 @@ This doc is the single distilled reference for `httpware` design rationale, prot
 
 ## 1. Project intent
 
-`httpware` is a thin opinionated wrapper around `httpx2`. It re-exports `httpx2.Request` and `httpx2.Response` as the public request/response surface and adds three things on top: typed response decoding (via a `ResponseDecoder` protocol; Pydantic ships as the default, msgspec as an opt-in extra), a middleware chain composed at client construction, and a status-keyed exception tree raised automatically on 4xx and 5xx.
+`httpware` is a thin opinionated wrapper around `httpx2`. It re-exports `httpx2.Request` and `httpx2.Response` as the public request/response surface and adds three things on top: typed response decoding (via a `ResponseDecoder` protocol; pydantic and msgspec are both opt-in extras as of 0.3.0), a middleware chain composed at client construction, and a status-keyed exception tree raised automatically on 4xx and 5xx. `AsyncClient(decoder=None)` defaults to constructing a `PydanticDecoder` and so requires the `pydantic` extra; callers can supply an explicit `decoder=` argument to escape the default.
 
 The 0.1.0 release attempted to own a full abstraction over the underlying HTTP client. v0.2 walks that back: `httpx2` is part of the public surface.
 
@@ -43,6 +43,7 @@ The 0.1.0 seams numbered 1 (Middleware↔Transport) and 4 (Transport↔httpx2) h
 - **Where:** `pyproject.toml` extras (`[project.optional-dependencies]`) ↔ the adapter modules that import them.
 - **Contract:** each optional dependency is imported only inside its own dedicated module (e.g., `pydantic` in `decoders/pydantic.py`; `msgspec` in `decoders/msgspec.py`; `opentelemetry` in `middleware/observability/otel.py` when Epic 5 lands).
 - **Rule:** never import an extra at package top-level. The package must import cleanly when the extra is not installed.
+- **Verification:** `tests/test_optional_extras_isolation.py` runs a fresh-subprocess `import httpware` and asserts that neither pydantic nor msgspec ends up in `sys.modules`. New extras must add the same isolation test.
 
 ## 4. Exception contract
 
@@ -102,7 +103,7 @@ msgspec = ["msgspec>=0.18"]
 otel = ["opentelemetry-api>=1.20", "opentelemetry-sdk>=1.20"]
 ```
 
-Each extra's code lives in a single dedicated module (e.g., `decoders/pydantic.py`, `decoders/msgspec.py`, `middleware/observability/otel.py`). The `import` of the extra happens **inside** that module — never at package top level. This way, `import httpware` works cleanly without the extras installed, and the seam stays observable: grep for `import pydantic` should return exactly one file.
+Each extra's code lives in a single dedicated module (`decoders/pydantic.py`, `decoders/msgspec.py`, `middleware/observability/otel.py` when Epic 5 lands). The `import` of the extra happens **inside** that module behind an `is_<extra>_installed` guard from `_internal/import_checker.py` — never at package top level. This way, `import httpware` works cleanly without the extras installed, and the seam stays observable: `grep -rnE 'from pydantic|import pydantic' src/httpware/ | grep -v import_checker` returns exactly one indented line (the guarded import in `decoders/pydantic.py`), and the same is true for `msgspec`.
 
 Caller-facing pattern: consumers select the implementation by passing it explicitly, e.g., `AsyncClient(decoder=PydanticDecoder())`. There is no auto-detection or implicit registry.