## Problem
The r-universe build of `wickra` 0.8.4 fails (`R CMD check` ERROR): the golden-fixture parity test added in #255 walks up from the working directory looking for `testdata/golden` and `stop()`s when it cannot find it. Standalone package builds (r-universe / CRAN) package only `bindings/r`, so the repo-root `testdata/golden` fixtures are unreachable there — whereas the monorepo CI checks out the full repo, so the walk-up succeeds and the test passes.
Run: https://github.com/r-universe/wickra-lib/actions/runs/27354800361
## Fix
- **`bindings/r/tests/testthat/test-golden.R`** — the fixture-directory lookup now returns `NULL` instead of erroring when the fixtures are absent, and each test starts with `skip_if(is.null(golden_dir), ...)`. The repository CI (full repo present) still runs the parity checks; standalone builds skip them. The per-test `golden_input` read moved inside the (post-skip) test bodies so nothing runs at source time when the fixtures are missing.
- **`CHANGELOG.md`** — `[Unreleased]` Fixed entry.
## Docs (B6)
- **`README.md` `## Testing`** — the four C-ABI bindings (C#, Go, Java, R) were described as covering one indicator per FFI archetype; document that they additionally replay the shared golden fixture and assert exact parity with the Rust reference outputs.
**Task 5 — golden-fixture parity for the C-ABI bindings.** Lifts the C#/Go/Java/R tests from *one indicator per archetype* toward reference-value parity, catching FFI wiring bugs (swapped params, wrong multi-output field) the math-only core tests cannot see.
## What's here
- **`examples/rust/src/bin/gen_golden.rs`** + **`testdata/golden/*.csv`** — a Rust generator computing a deterministic OHLCV series plus the core's reference outputs for a curated archetype-spanning set: scalar (`Sma`/`Ema`/`Rsi`), candle (`Atr`), scalar multi-output (`MACD`), candle multi-output (`ADX`), pairwise (`Beta`). `nan` marks warmup. Regenerate with `cargo run -p wickra-examples --bin gen_golden`.
- **Parity runners** replaying the identical fixtures through each FFI (rel-tol 1e-6), each a standard test in the binding's existing suite (no `ci.yml` change — rides `dotnet test` / `go test` / `mvn install` / `R CMD`+testthat). A walk-up search locates `testdata/golden` regardless of run dir.
- **C#** (`bindings/csharp/.../GoldenTests.cs`) — ✅ validated locally, 7/7 pass.
- **Go** (`bindings/go/golden_test.go`) — ✅ validated locally, pass.
- **Java** (`bindings/java/.../GoldenTests.java`) — modeled on the archetype API; validated by CI (no local mvn).
- **R** (`bindings/r/tests/testthat/test-golden.R`) — modeled on the archetype API; validated by CI (no local Rscript).
## Notes
- The curated set spans every marshalling archetype; extending the indicator list is mechanical (add to the generator + regenerate). Bars/profile archetypes can be added next.
- No new CI jobs.
Adds an R binding (`bindings/r`) over the C ABI hub — the third language stecker after C# and Go, reaching the hub through R's native `.Call` interface (not extendr).
## What's here
- **`bindings/r`** — an R package exposing all 514 indicators as constructors that return a `wickra_indicator` object with generic `update`/`batch`/`reset` methods. The C glue (`src/wickra.c`) and R wrappers (`R/indicators.R`) are generated from `bindings/c/include/wickra.h` (same archetype taxonomy as the C#/Go generators: scalar/batch, multi-output, bars, profile, profile-values, array-input). The opaque handle is an R external pointer freed by a registered finalizer; multi-output returns a named vector (`NA` at warmup), bars a matrix, profiles a list.
- **`examples/r`** — the full example suite mirroring C/C#/Go: streaming, backtest, multi_timeframe, parallel_assets (`mclapply`), three strategies, and `fetch_btcusdt`/`live_binance`.
- **CI** — an `r` job builds the C ABI library, installs the package, runs the `testthat` suite and the offline examples on Linux, macOS and Windows (`R CMD check` is clean: 0 warnings, 0 notes).
- **Docs** — R added to the README languages table, project layout, building/testing, CONTRIBUTING binding table + regenerate note, ARCHITECTURE, examples index, issue/PR templates, the About-description template, and the other binding READMEs.
## Linking / distribution
The package compiles a thin `.Call` glue layer against the prebuilt C ABI library (header via `WICKRA_INCLUDE_DIR`, library via `WICKRA_LIB_DIR`). On Windows the package's own `wickra.dll` would collide with the C ABI's `wickra.dll`, so `configure.win` stages a renamed copy (`wickra_abi.dll`) and builds an import library referencing it; `install.libs.R` bundles the DLL and `.onLoad` puts it on the load path. On Linux/macOS the rpath locates the shared library. No `release.yml` change — R is distributed via r-universe / source install (gated).
No Rust crate or `Cargo.toml` change — the R package is standalone and additive.
kingchenc