🤖 refactor: use conditional RUNNER variable for Windows compatibility

- Add RUNNER variable that uses npx on Windows, bun x elsewhere
- Windows: bun x doesn't correctly pass arguments, so use npm run/npx
- Non-Windows: Continue using bun x for better performance
- Update all commands to use $(RUNNER) instead of hardcoded bun x
- Add comments explaining why Windows needs different approach

This ensures consistent build behavior across all platforms while
working around Windows-specific limitations with bun's argument passing.

Author: ibetitsmike

Makefile

@@ -23,6 +23,14 @@
 #   AVOID CONDITIONAL BRANCHES (if/else) IN BUILD TARGETS AT ALL COSTS.
 #   Branches reduce reproducibility - builds should fail fast with clear errors
 #   if dependencies are missing, not silently fall back to different behavior.
+# Platform detection for cross-platform compatibility
+ifeq ($(OS),Windows_NT)
+# Windows: Use npm/npx because $(RUNNER) doesn't correctly pass arguments on Windows
+RUNNER := npx
+else
+# Non-Windows: Use $(RUNNER) for better performance
+RUNNER := bun x
+endif
 
 # Enable parallel execution by default (only if user didn't specify -j)
 ifeq (,$(filter -j%,$(MAKEFLAGS)))
@@ -97,8 +105,9 @@ help: ## Show this help message
 
 ## Development
 dev: node_modules/.installed build-main ## Start development server (Vite + tsgo watcher for 10x faster type checking)
-	@bun x concurrently -k \
-		"bun x concurrently \"$(TSGO) -w -p tsconfig.main.json\" \"bun x tsc-alias -w -p tsconfig.main.json\"" \
+	@# On Windows, use npm run because bun x doesn't correctly pass arguments
+	@$(RUNNER) concurrently -k \
+		"$(RUNNER) concurrently \"$(TSGO) -w -p tsconfig.main.json\" \"$(RUNNER) tsc-alias -w -p tsconfig.main.json\"" \
 		"vite"
 
 dev-server: node_modules/.installed build-main ## Start server mode with hot reload (backend :3000 + frontend :5173). Use VITE_HOST=0.0.0.0 BACKEND_HOST=0.0.0.0 for remote access
@@ -107,15 +116,16 @@ dev-server: node_modules/.installed build-main ## Start server mode with hot rel
 	@echo "  Frontend (with HMR):     http://$(or $(VITE_HOST),localhost):$(or $(VITE_PORT),5173)"
 	@echo ""
 	@echo "For remote access: make dev-server VITE_HOST=0.0.0.0 BACKEND_HOST=0.0.0.0"
-	@bun x concurrently -k \
-		"bun x concurrently \"$(TSGO) -w -p tsconfig.main.json\" \"bun x tsc-alias -w -p tsconfig.main.json\"" \
-		"bun x nodemon --watch dist/main.js --watch dist/main-server.js --delay 500ms --exec 'node dist/main.js server --host $(or $(BACKEND_HOST),localhost) --port $(or $(BACKEND_PORT),3000)'" \
+	@# On Windows, use npm run because bun x doesn't correctly pass arguments
+	@$(RUNNER) concurrently -k \
+		"$(RUNNER) concurrently \"$(TSGO) -w -p tsconfig.main.json\" \"$(RUNNER) tsc-alias -w -p tsconfig.main.json\"" \
+		"$(RUNNER) nodemon --watch dist/main.js --watch dist/main-server.js --delay 500ms --exec 'node dist/main.js server --host $(or $(BACKEND_HOST),localhost) --port $(or $(BACKEND_PORT),3000)'" \
 		"CMUX_VITE_HOST=$(or $(VITE_HOST),127.0.0.1) CMUX_VITE_PORT=$(or $(VITE_PORT),5173) VITE_BACKEND_URL=http://$(or $(BACKEND_HOST),localhost):$(or $(BACKEND_PORT),3000) vite"
 
 
 
 start: node_modules/.installed build-main build-preload build-static ## Build and start Electron app
-	@bun x electron --remote-debugging-port=9222 .
+	@$(RUNNER) electron --remote-debugging-port=9222 .
 
 ## Build targets (can run in parallel)
 build: node_modules/.installed src/version.ts build-renderer build-main build-preload build-icons build-static ## Build all targets
@@ -125,7 +135,7 @@ build-main: node_modules/.installed dist/main.js ## Build main process
 dist/main.js: src/version.ts tsconfig.main.json tsconfig.json $(TS_SOURCES)
 	@echo "Building main process..."
 	@NODE_ENV=production $(TSGO) -p tsconfig.main.json
-	@NODE_ENV=production bun x tsc-alias -p tsconfig.main.json
+	@NODE_ENV=production $(RUNNER) tsc-alias -p tsconfig.main.json
 
 build-preload: node_modules/.installed dist/preload.js ## Build preload script
 
@@ -140,7 +150,7 @@ dist/preload.js: src/preload.ts $(TS_SOURCES)
 
 build-renderer: node_modules/.installed src/version.ts ## Build renderer process
 	@echo "Building renderer..."
-	@bun x vite build
+	@$(RUNNER) vite build
 
 build-static: ## Copy static assets to dist
 	@echo "Copying static assets..."
@@ -192,15 +202,16 @@ lint-fix: node_modules/.installed ## Run linter with --fix
 	@./scripts/lint.sh --fix
 
 typecheck: node_modules/.installed src/version.ts ## Run TypeScript type checking (uses tsgo for 10x speedup)
-	@bun x concurrently -g \
+	@# On Windows, use npm run because bun x doesn't correctly pass arguments
+	@$(RUNNER) concurrently -g \
 		"$(TSGO) --noEmit" \
 		"$(TSGO) --noEmit -p tsconfig.main.json"
 
 check-deadcode: node_modules/.installed ## Check for potential dead code (manual only, not in static-check)
 	@echo "Checking for potential dead code with ts-prune..."
 	@echo "(Note: Some unused exports are legitimate - types, public APIs, entry points, etc.)"
 	@echo ""
-	@bun x ts-prune -i '(test|spec|mock|bench|debug|storybook)' \
+	@$(RUNNER) ts-prune -i '(test|spec|mock|bench|debug|storybook)' \
 		| grep -v "used in module" \
 		| grep -v "src/App.tsx.*default" \
 		| grep -v "src/types/" \
@@ -210,7 +221,7 @@ check-deadcode: node_modules/.installed ## Check for potential dead code (manual
 ## Testing
 test-integration: node_modules/.installed build-main ## Run all tests (unit + integration)
 	@bun test src
-	@TEST_INTEGRATION=1 bun x jest tests
+	@TEST_INTEGRATION=1 $(RUNNER) jest tests
 
 test-unit: node_modules/.installed build-main ## Run unit tests
 	@bun test src
@@ -225,52 +236,52 @@ test-coverage: ## Run tests with coverage
 
 test-e2e: ## Run end-to-end tests
 	@$(MAKE) build
-	@CMUX_E2E_LOAD_DIST=1 CMUX_E2E_SKIP_BUILD=1 PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD=1 bun x playwright test --project=electron $(PLAYWRIGHT_ARGS)
+	@CMUX_E2E_LOAD_DIST=1 CMUX_E2E_SKIP_BUILD=1 PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD=1 $(RUNNER) playwright test --project=electron $(PLAYWRIGHT_ARGS)
 
 ## Distribution
 dist: build ## Build distributable packages
-	@bun x electron-builder --publish never
+	@$(RUNNER) electron-builder --publish never
 
 # Parallel macOS builds - notarization happens concurrently
 dist-mac: build ## Build macOS distributables (x64 + arm64)
 	@if [ -n "$$CSC_LINK" ]; then \
 		echo "🔐 Code signing enabled - building sequentially to avoid keychain conflicts..."; \
-		bun x electron-builder --mac --x64 --publish never && \
-		bun x electron-builder --mac --arm64 --publish never; \
+		$(RUNNER) electron-builder --mac --x64 --publish never && \
+		$(RUNNER) electron-builder --mac --arm64 --publish never; \
 	else \
 		echo "Building macOS architectures in parallel..."; \
-		bun x electron-builder --mac --x64 --publish never & pid1=$$! ; \
-		bun x electron-builder --mac --arm64 --publish never & pid2=$$! ; \
+		$(RUNNER) electron-builder --mac --x64 --publish never & pid1=$$! ; \
+		$(RUNNER) electron-builder --mac --arm64 --publish never & pid2=$$! ; \
 		wait $$pid1 && wait $$pid2; \
 	fi
 	@echo "✅ Both architectures built successfully"
 
 dist-mac-release: build ## Build and publish macOS distributables (x64 + arm64)
 	@if [ -n "$$CSC_LINK" ]; then \
 		echo "🔐 Code signing enabled - building sequentially to avoid keychain conflicts..."; \
-		bun x electron-builder --mac --x64 --publish always && \
-		bun x electron-builder --mac --arm64 --publish always; \
+		$(RUNNER) electron-builder --mac --x64 --publish always && \
+		$(RUNNER) electron-builder --mac --arm64 --publish always; \
 	else \
 		echo "Building and publishing macOS architectures in parallel..."; \
-		bun x electron-builder --mac --x64 --publish always & pid1=$$! ; \
-		bun x electron-builder --mac --arm64 --publish always & pid2=$$! ; \
+		$(RUNNER) electron-builder --mac --x64 --publish always & pid1=$$! ; \
+		$(RUNNER) electron-builder --mac --arm64 --publish always & pid2=$$! ; \
 		wait $$pid1 && wait $$pid2; \
 	fi
 	@echo "✅ Both architectures built and published successfully"
 
 dist-mac-x64: build ## Build macOS x64 distributable only
 	@echo "Building macOS x64..."
-	@bun x electron-builder --mac --x64 --publish never
+	@$(RUNNER) electron-builder --mac --x64 --publish never
 
 dist-mac-arm64: build ## Build macOS arm64 distributable only
 	@echo "Building macOS arm64..."
-	@bun x electron-builder --mac --arm64 --publish never
+	@$(RUNNER) electron-builder --mac --arm64 --publish never
 
 dist-win: build ## Build Windows distributable
-	@bun x electron-builder --win --publish never
+	@$(RUNNER) electron-builder --win --publish never
 
 dist-linux: build ## Build Linux distributable
-	@bun x electron-builder --linux --publish never
+	@$(RUNNER) electron-builder --linux --publish never
 
 ## VS Code Extension (delegates to vscode/Makefile)
 
@@ -293,19 +304,19 @@ docs-watch: ## Watch and rebuild documentation
 ## Storybook
 storybook: node_modules/.installed ## Start Storybook development server
 	$(check_node_version)
-	@bun x storybook dev -p 6006 $(STORYBOOK_OPEN_FLAG)
+	@$(RUNNER) storybook dev -p 6006 $(STORYBOOK_OPEN_FLAG)
 
 storybook-build: node_modules/.installed src/version.ts ## Build static Storybook
 	$(check_node_version)
-	@bun x storybook build
+	@$(RUNNER) storybook build
 
 test-storybook: node_modules/.installed ## Run Storybook interaction tests (requires Storybook to be running or built)
 	$(check_node_version)
-	@bun x test-storybook
+	@$(RUNNER) test-storybook
 
 chromatic: node_modules/.installed ## Run Chromatic for visual regression testing
 	$(check_node_version)
-	@bun x chromatic --exit-zero-on-changes
+	@$(RUNNER) chromatic --exit-zero-on-changes
 
 ## Benchmarks
 benchmark-terminal: ## Run Terminal-Bench with the cmux agent (use TB_DATASET/TB_SAMPLE_SIZE/TB_TIMEOUT/TB_ARGS to customize)