docs: record experimental-tier exclusion (CCtxParams) in binding scope

The ZSTD_CCtx_params bundle is ZSTDLIB_STATIC_API (experimental, gated
behind ZSTD_STATIC_LINKING_ONLY, no stability guarantee, and not
guaranteed to survive the -fvisibility=hidden export table). It only
saves a few setParameter calls at context init and the bound per-context
ZSTD_CCtx_setParameter path covers the same need, so it is intentionally
not bound. Extend ADR 0013 to exclude the experimental tier and note the
reason on the supported.md Advanced parameters row.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: dfa1

adr/0013-binding-coverage-scope.md

@@ -18,6 +18,15 @@ training), and frame/skippable-frame introspection. **Exclude** deprecated
 functions and the `legacy/` and `deprecated/` source trees (the native build
 compiles only `common`, `compress`, `decompress`, `dictBuilder`).
 
+Also **exclude the experimental tier** — symbols declared `ZSTDLIB_STATIC_API`
+(reachable only under `ZSTD_STATIC_LINKING_ONLY`, no stability guarantee, and
+not guaranteed to survive the `-fvisibility=hidden` export table). Notably this
+covers the `ZSTD_CCtx_params` bundle (`ZSTD_createCCtxParams`,
+`ZSTD_CCtxParams_setParameter`, `ZSTD_CCtx_setParametersUsingCCtxParams`, …):
+it only saves a few `setParameter` calls at context init — never on a hot path —
+so the experimental-API risk is not worth the marginal value. The per-context
+`ZSTD_CCtx_setParameter` path (already bound) covers the same need.
+
 The full coverage map — every public symbol, what is bound, and what is
 intentionally omitted — is maintained in `docs/supported.md`.
 

docs/supported.md

@@ -33,7 +33,7 @@ rather than the deprecated `ZSTD_getDecompressedSize`.
 | Dictionary training (ZDICT) | 8 / 12 | trainFromBuffer, cover/fastCover optimizers, finalizeDictionary, getDictHeaderSize |
 | Streaming — compress | 3 / 22 | `ZstdOutputStream` (compressStream2 + buffer sizes) |
 | Streaming — decompress | 3 / 15 | `ZstdInputStream` (decompressStream + buffer sizes) |
-| Advanced parameters | 14 / 38 | all `ZSTD_cParameter` + `ZSTD_dParameter` via `ZstdCompressParameter`/`ZstdDecompressParameter`; `compress2`, `C/DCtx_setParameter`, `C/DCtx_reset`, `C/DCtx_loadDictionary`, `CCtx_refCDict`/`DCtx_refDDict`, `C/DCtx_refPrefix`, `c/dParam_getBounds`; MT inert on single-thread build |
+| Advanced parameters | 14 / 38 | all `ZSTD_cParameter` + `ZSTD_dParameter` via `ZstdCompressParameter`/`ZstdDecompressParameter`; `compress2`, `C/DCtx_setParameter`, `C/DCtx_reset`, `C/DCtx_loadDictionary`, `CCtx_refCDict`/`DCtx_refDDict`, `C/DCtx_refPrefix`, `c/dParam_getBounds`; MT inert on single-thread build. The `CCtxParams` cluster is experimental (`ZSTDLIB_STATIC_API`) and intentionally unbound — see [ADR 0013](../adr/0013-binding-coverage-scope.md) |
 | Frame inspection | 12 / 13 | `ZstdFrame` + getFrameProgression; `_advanced` not bound |
 | Memory sizing | 9 / 14 | sizeof_C/DCtx, sizeof_C/DDict, estimate C/DCtx + C/DDict size, in-place decompression margin |
 | Low-level block | 0 / 12 | expert block/continue API not bound |