Latest merge from Hunter. Also a couple files I forgot to add yesterday.

CONTRIBUTING.md

@@ -36,8 +36,7 @@ Record changed behavior and remaining acceptance gaps in the contribution descri
 Use Go 1.24 or newer, CGO, `pkg-config`, and development libraries for GTK3, AT-SPI, GStreamer, and X11. Braille builds also require BRLTTY/BrlAPI and liblouis. The Arch `PKGBUILD` lists runtime and build dependencies.
 
 ```sh
-go build -o build/cthulhu ./cmd/cthulhu
-go build -tags brlapi -o build/cthulhu-braille ./cmd/cthulhu-braille
+./build-cthulhu.sh --output-dir build
 go test ./... -count=1
 go test -race ./... -count=1
 go test -tags brlapi ./... -count=1
@@ -46,6 +45,13 @@ go build ./cmd/...
 go run ./cmd/parityledger validate testdata/parity-ledger.csv
 ```
 
+The build script selects or bootstraps Go without changing the system
+installation; see [Building](README.md#building) for packaging, cache and
+offline controls. Direct `go test`, `go vet` and other Go commands still need
+a suitable Go executable on `PATH` (Go 1.21+ can select newer toolchains).
+Build-script regression checks run with `python3 tests/test_build_script.py -v`;
+they use isolated fake tools and require no network or running reader.
+
 Start verification with the affected packages; run broader checks when the change affects shared behavior or before submission where practical. Format edited Go files with `gofmt`; run `shellcheck` for edited shell scripts. Use deterministic tests and synchronization instead of timing sleeps. Keep fixtures generic, without real usernames or personal identifiers.
 
 ### Version update pre-commit hook