[omerbek]

Problem

HTTP media type names are case-insensitive (RFC 9110 §8.3.1), but the response parser checks content_type.endswith("json") case-sensitively.

Through the public simple.price.get() resource, a valid Content-Type: Application/JSON success response returns a raw string in loose mode, causing price["bitcoin"].usd to raise TypeError. Strict mode instead raises APIResponseValidationError. Lowercase application/json works. This affects dictionary/list response types that do not use the BaseModel JSON fallback. I do not claim CoinGecko's live API currently emits this casing.

Change

Normalize casing only for the existing JSON suffix comparison. Preserve the existing content-type acceptance scope and fallback behavior. Add 32 sync/async dictionary/list regression cases across loose/strict validation, lowercase/mixed/uppercase types, charset parameters, and a mixed-case JSON suffix; document case-insensitive parsing.

This is independent of the environment-copy fix in the separate open PR; it branches directly from current main (83af7a13bd615e4ee87c1443aa53a6baf34bdcff) and does not modify client configuration. The complete authenticated open+closed issue/PR inventory (53 entries) and relevant prior review/comments/timeline did not identify a duplicate or ownership claim. CONTRIBUTING.md explicitly permits manual patches that persist across generation. No generator config was invented.

Verification

Windows; supported Python 3.11.5, httpx 0.28.1, pydantic 2.14.3, pytest 9.2.0:

• Before the fix, standalone sync/async simple.price.get() calls using httpx.MockTransport reproduced the consumer TypeError in loose mode and content-type validation error in strict mode for both mixed/uppercase JSON headers. Lowercase controls succeeded.
• python -m pytest tests/test_response.py -n 0: 58 passed.
• python -m ruff check src/coingecko_sdk/_response.py tests/test_response.py: passed.
• python -m ruff format tests/test_response.py: unchanged.
• Post-fix standalone public-resource smoke: all 12 success-response combinations returned a dictionary with typed usd=1.0; all 12 HTTP 400 combinations preserved BadRequestError and its dictionary error body. Error responses were not affected by this bug before the change either.
• Separate standalone public-resource checks preserved loose-mode raw text and strict-mode validation errors for text/plain, sync and async.

All HTTP responses were supplied offline; no real API key, network API call, RPC, or funds were used. No LSP is configured in this environment; source references/callers were checked by text search instead.

The repository pins development Python 3.9.18. This run used a lightweight supported-3.11 venv rather than the pinned development lock (the lock's backports-asyncio-runner==1.2.0 requires Python <3.11). The pinned-3.9 environment, Pydantic v1 matrix, full client/Prism-backed resource suite, and full typecheck were not run. Temporary local dependencies were removed after verification.

Risk / compatibility

No public symbols, signatures, client settings, or non-JSON fallback logic change. Already-supported JSON suffixes are compared case-insensitively; malformed/non-JSON content is not newly treated as JSON otherwise.

AI-assisted investigation and implementation; all runtime/test results above were actually exercised locally.