Mac mini support: arm64 cross-build installed beside the binary and pushed by arch; ARM machine name from the device tree

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Makefile

@@ -23,7 +23,11 @@ go:
 dev:
 	cd web && npm run dev
 
-deploy: build
+# arm64 sibling for aarch64 machines (Mac mini); the hub pushes it to them
+cross:
+	CGO_ENABLED=0 GOOS=linux GOARCH=arm64 $(GO) build -trimpath -ldflags "-s -w -X main.version=$(VERSION)" -o bin/hamlab-linux-arm64 ./cmd/hamlab
+
+deploy: build cross
 	./deploy/install.sh
 	@sleep 1; $(PREFIX)/hamlab push-nodes || true
 

PLAN.md

@@ -200,7 +200,10 @@ something long in one, switch away and back, refresh — it's all still there.
   it last, so one deploy on the hub updates every machine. First install on a new host
   is still by hand (scp binary + `install.sh`, `hamlab passwd`, `tls auto`). Still to
   do: Phase 2 Datacenter overview; optional firewall rule limiting a node's port to
-  the hub; cross-architecture builds for the Mac mini.
+  the hub. **Cross-architecture** (2026-09-18): `make deploy` also builds
+  `bin/hamlab-linux-arm64`, `install.sh` installs it beside the binary as
+  `hamlab-arm64`, and the hub picks the sibling matching a node's `/api/me.arch` when
+  pushing — the Mac mini (Fedora Asahi, aarch64, node `mac`) updates like the rest.
 - **Auth hardening** — WebAuthn passkeys (phone Face ID), TOTP fallback, session
   list + revoke, optional NPM access list restricting to WireGuard/LAN.
 - **Files tab** — **shipped 2026-09-18** (`internal/files`, `Files.tsx`): browse from

README.md

@@ -36,6 +36,8 @@ through the switcher at the top of the rail.
 Updating: `make deploy` on the hub installs the new build there and then pushes it to
 every managed machine (`hamlab push-nodes`), which install it and restart. The Machines
 page flags machines running an older version and offers the same push per machine.
+Mixed architectures are fine: `make deploy` also cross-compiles arm64, and the hub sends
+each machine the build for its own architecture.
 
 - On `core` it is public at `https://hamlab.bigham.dev` behind Nginx Proxy Manager.
 - Installable as a PWA.

deploy/install.sh

@@ -19,6 +19,10 @@ sed -e "s|@USER@|$USER_NAME|g" -e "s|@GROUP@|$GROUP_NAME|g" -e "s|@HOME@|$HOME_D
   deploy/hamlab.service > "$unit"
 
 sudo install -m 0755 bin/hamlab "$PREFIX/hamlab"
+# other-architecture builds sit beside the binary so the hub can push them to matching machines
+for alt in bin/hamlab-linux-*; do
+  [ -f "$alt" ] && sudo install -m 0755 "$alt" "$PREFIX/hamlab-${alt##*-linux-}"
+done
 sudo install -m 0644 "$unit" /etc/systemd/system/hamlab.service
 rm -f "$unit"
 sudo systemctl daemon-reload

internal/metrics/metrics.go

@@ -914,6 +914,12 @@ var cpuModel = func() string {
 			}
 		}
 	}
+	// ARM boards don't put a model name in cpuinfo; the device tree names the machine.
+	for _, p := range []string{"/sys/firmware/devicetree/base/model", "/proc/device-tree/model", "/sys/devices/virtual/dmi/id/product_name"} {
+		if m := strings.TrimRight(strings.TrimSpace(readStr(p)), "\x00"); m != "" {
+			return m
+		}
+	}
 	return ""
 }()
 

internal/nodes/nodes.go

@@ -313,8 +313,13 @@ func (m *Manager) Push(ctx context.Context, name, binPath, ourArch string) PushR
 	_ = json.NewDecoder(io.LimitReader(resp.Body, 64<<10)).Decode(&me)
 	resp.Body.Close()
 	if me.Arch != "" && ourArch != "" && me.Arch != ourArch {
-		res.Error = fmt.Sprintf("architecture mismatch: node is %s, this binary is %s — build for it and deploy by hand", me.Arch, ourArch)
+		// look for a sibling build: /usr/local/bin/hamlab-arm64 next to /usr/local/bin/hamlab
-		return res
+		alt := binPath + "-" + me.Arch
+		if _, err := os.Stat(alt); err != nil {
+			res.Error = fmt.Sprintf("node is %s but only a %s build is installed here (expected %s; run make deploy, which builds it)", me.Arch, ourArch, alt)
+			return res
+		}
+		binPath = alt
 	}
 	f, err := os.Open(binPath)
 	if err != nil {