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

The ZSTD_CCtx_params bundle is ZSTDLIB_STATIC_API — experimental tier.
The symbols are exported (the macro resolves to visibility("default"),
so the FFM layer could bind them by name), but they carry no API-stability
guarantee and may change or be removed between zstd releases. The bundle
only saves a few setParameter calls at context init, and the stable
per-context ZSTD_CCtx_setParameter path (already bound) 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

@@ -1,4 +1,4 @@
-# ADR 0013: Binding coverage scope — exclude legacy/deprecated
+# ADR 0013: Binding coverage scope — exclude legacy/deprecated/experimental
 
 - **Status:** Accepted
 - **Date:** 2026-06-27
@@ -18,6 +18,16 @@ 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`.
+These are exported by the build (the macro resolves to `visibility("default")`,
+so the FFM layer could bind them by name), but they carry no API-stability
+guarantee and may change or be removed between zstd releases. 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 stable,
+already-bound per-context `ZSTD_CCtx_setParameter` path 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`, no stability guarantee — exported, but intentionally not surfaced) — 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 |