make lan: a fresh distd always serving the .lan store on the LAN

Rebuilds, frees the port (stale servers from earlier sessions squat on
it), and restarts detached on 0.0.0.0:8787; the .lan/ store and its log
are long-lived and gitignored.

.gitignore

@@ -9,5 +9,8 @@ build/
 # scratch store roots / fixtures created by tests (never /tmp)
 .sx-tmp/
 
+# the long-running LAN demo store served by `make lan`
+.lan/
+
 # sx compiler caches (object cache for #import c units etc.)
 .sx-cache/

Makefile

@@ -20,7 +20,7 @@ BUILD_DIR := build
 SMOKE := tests/smoke.sx
 DIST  := src/dist.sx
 
-.PHONY: build test publish-example clean
+.PHONY: build test publish-example lan clean
 
 # Compile the product sources (and the smoke program) without running.
 build:
@@ -42,5 +42,19 @@ publish-example: build
 	@rm -rf .sx-tmp/publish-example
 	./$(BUILD_DIR)/dist ci publish --manifest examples/dist.json --local-store .sx-tmp/publish-example --json
 
+# Serve the persistent .lan/ store on 0.0.0.0:$(LAN_PORT) for LAN access.
+# Rebuilds first and REPLACES any running instance, so the served binary
+# is always the current tree. Detached via nohup; log lives with the
+# store's other state (one data dir, like the /data volume in PLAN.md).
+LAN_PORT  ?= 8787
+LAN_STORE ?= .lan
+
+lan: build
+	@pkill -f "dist server run --local-store $(LAN_STORE)" 2>/dev/null || true
+	@lsof -tiTCP:$(LAN_PORT) -sTCP:LISTEN | xargs kill 2>/dev/null || true; sleep 0.3
+	@mkdir -p $(LAN_STORE)
+	@sh -c 'nohup ./$(BUILD_DIR)/dist server run --local-store $(LAN_STORE) --port $(LAN_PORT) >> $(LAN_STORE)/distd.log 2>&1 & echo "distd pid $$!"'
+	@echo "admin:  http://$$(ipconfig getifaddr en0 2>/dev/null || echo localhost):$(LAN_PORT)/admin"
+
 clean:
 	@rm -rf $(BUILD_DIR) .sx-cache