smarter makefile: only re-run chat build if sources haven't changed

Author: hugodutka

Makefile

@@ -1,7 +1,17 @@
-embed:
+CHAT_SOURCES_STAMP = chat/.sources.stamp
+CHAT_SOURCES = $(shell find chat \( -path chat/node_modules -o -path chat/out -o -path chat/.next \) -prune -o -not -path chat/.sources.stamp -type f -print)
+
+$(CHAT_SOURCES_STAMP): $(CHAT_SOURCES)
+	@echo "Chat sources changed. Running build steps..."
 	cd chat && bun run build
 	rm -rf lib/httpapi/chat && mkdir -p lib/httpapi/chat && touch lib/httpapi/chat/marker
 	cp -r chat/out/. lib/httpapi/chat/
+	touch $@
+
+.PHONY: embed
+embed: $(CHAT_SOURCES_STAMP)
+	@echo "Chat build is up to date."
 
+.PHONY: build
 build: embed
 	go build -o agentapi main.go

chat/.gitignore

@@ -39,3 +39,4 @@ yarn-error.log*
 # typescript
 *.tsbuildinfo
 next-env.d.ts
+.sources.stamp