fix(patches): validator portability, clearer docs, broader hook trigger

.superpowers/handoff/task-B1-brief.md

@@ -0,0 +1,44 @@
+### Task B1: Create the patch registry with the RcppParallel entry
+
+**Files:**
+- Create: `local/patches/registry.json`
+- Create: `local/patches/README.md`
+
+**Interfaces:**
+- Produces: the curated registry consumed by bincraft's `patches` argument.
+
+- [ ] **Step 1: Write the registry**
+
+```json
+[
+  {
+    "package": "RcppParallel",
+    "versions": "*",
+    "platforms": ["alpine", "ubuntu-2604"],
+    "env": { "RCPP_PARALLEL_USE_TBB": "0" },
+    "configure_args": [],
+    "makevars": {},
+    "patch": null,
+    "reason": "bundled Intel TBB fails to build on musl and on newer toolchains (e.g. g++ 15 on ubuntu-2604); disabling TBB falls back to TinyThread"
+  }
+]
+```
+
+- [ ] **Step 2: Write the README**
+
+`local/patches/README.md` documents the schema (copy the field table from `specs/2026-06-30-package-patching-design.md`), how to add an entry, and that source diffs go in `local/patches/<pkg>/<file>.patch` referenced by the `patch` field.
+
+- [ ] **Step 3: Verify it parses**
+
+Run: `Rscript -e 'x <- jsonlite::fromJSON("local/patches/registry.json", simplifyVector = FALSE); stopifnot(length(x) == 1L, x[[1]]$package == "RcppParallel"); cat("ok\n")'`
+Expected: `ok`.
+
+- [ ] **Step 4: Commit**
+
+```bash
+git add local/patches/registry.json local/patches/README.md
+git commit -m "feat(patches): add patch registry with RcppParallel TBB workaround"
+```
+
+---
+