tinygo-gate: also build the Pico firmware, not just the amd64 core shim

cmd/cs-tinygo (the amd64 gate target) never imports client/link, so it
missed the localtalk.go/localtalk_tinygo.go signature drift that broke
PR #20's separate "Build Embedded (TinyGo)" job. hardware/pico does pull
in client/link, so building it here closes that gap for `make tinygo-gate`.

Author: pgodwin

Makefile

@@ -145,9 +145,12 @@ harness:
 archtest:
 	go test -count=1 ./core/internal/archtest/...
 
-# tinygo-gate runs the TinyGo amd64 build gates (linux + windows). Requires
-# tinygo on PATH; CI installs it. This is how the no-reflection /
-# no-forbidden-import discipline is verified without ESP32 hardware.
+# tinygo-gate runs the TinyGo amd64 build gates (linux + windows) plus the
+# Pico firmware build (hardware/pico, which — unlike the amd64 cmd/cs-tinygo
+# shim — imports client/link, so this also catches a localtalk.go /
+# localtalk_tinygo.go signature drift locally). Requires tinygo on PATH; CI
+# installs it. This is how the no-reflection / no-forbidden-import discipline
+# is verified without ESP32 hardware.
 tinygo-gate:
 	bash scripts/ci/tinygo-gate.sh
 

scripts/ci/tinygo-gate.sh

@@ -14,9 +14,16 @@ set -euo pipefail
 # embedded-compilability. Do not assume one substitutes for the other. See
 # .refactor/00-DESIGN.md errata note for A4.
 #
-# The compiled package is cmd/cs-tinygo, a minimal main that imports only the
+# The amd64 build is cmd/cs-tinygo, a minimal main that imports only the
 # TinyGo-safe core subset. Its import surface grows as more of core becomes
 # TinyGo-clean. See .refactor/01-PHASE-harness.md step A4.
+#
+# cmd/cs-tinygo does NOT import client/link (LToUDP/TashTalk openers), so a
+# signature drift between localtalk.go and its localtalk_tinygo.go stub can
+# pass this gate and only fail the separate "Build Embedded (TinyGo)" CI job
+# (hardware/pico, which does import client/link). To catch that class of break
+# locally, this gate also does the real -target=pico firmware build below —
+# the same one PR CI runs — rather than relying on the amd64 shim alone.
 
 TARGET_PKG="./cmd/cs-tinygo"
 
@@ -36,4 +43,8 @@ echo "=== build-tinygo-windows-amd64 ==="
 GOOS=windows GOARCH=amd64 tinygo build -o cs-tinygo.exe "${TARGET_PKG}"
 rm -f cs-tinygo.exe
 
-echo "tinygo-gate.sh: OK (both amd64 gates green)"
+echo "=== build-pico: hardware/pico full firmware (RP2040) ==="
+bash scripts/build_pico.sh pico
+rm -f bin/classicstack-pico.uf2
+
+echo "tinygo-gate.sh: OK (amd64 gates + Pico firmware build green)"