pass build id through to clsi when requesting pdf

services/web/app/coffee/Features/Compile/ClsiManager.coffee

@@ -54,6 +54,7 @@ module.exports = ClsiManager =
 			outputFiles.push
 				path: url.parse(file.url).path.replace("/project/#{project_id}/output/", "")
 				type: file.type
+				build: file.build
 		return outputFiles
 
 	VALID_COMPILERS: ["pdflatex", "latex", "xelatex", "lualatex"]

services/web/app/coffee/Features/Compile/CompileController.coffee

@@ -85,15 +85,20 @@ module.exports = CompileController =
 		url = "#{compilerUrl}#{url}"
 		logger.log url: url, "proxying to CLSI"
 		oneMinute = 60 * 1000
-		# pass through If-* and Range headers for byte serving pdfs
-		# do not send any others, potential proxying loop if Host: is passed!
+		# the base request
+		options = { url: url, method: req.method,	timeout: oneMinute }
+		# if we have a build parameter, pass it through to the clsi
+		if req.query?.build?
+			options.qs = {}
+			options.qs.build = req.query.build
+		# if we are byte serving pdfs, pass through If-* and Range headers
+		# do not send any others, there's a proxying loop if Host: is passed!
 		if req.query?.pdfng
 			newHeaders = {}
 			for h, v of req.headers
 				newHeaders[h] = req.headers[h] if h.match /^(If-|Range)/i
-			proxy = request(url: url, method: req.method, timeout: oneMinute, headers: newHeaders)
-		else
-			proxy = request(url: url, method: req.method, timeout: oneMinute)
+			options.headers = newHeaders
+		proxy = request(options)
 		proxy.pipe(res)
 		proxy.on "error", (error) ->
 			logger.warn err: error, url: url, "CLSI proxy error"

services/web/public/coffee/ide/pdf/controllers/PdfController.coffee

@@ -41,12 +41,17 @@ define [
 				$scope.pdf.failure = true
 				fetchLogs()
 			else if response.status == "success"
+				$scope.pdf.url = "/project/#{$scope.project_id}/output/output.pdf?cache_bust=#{Date.now()}"
 				if response.compileGroup?
 					$scope.pdf.compileGroup = response.compileGroup
-					$scope.pdf.url = "/project/#{$scope.project_id}/output/output.pdf?cache_bust=#{Date.now()}" +
-						"&compileGroup=#{$scope.pdf.compileGroup}"
-				else
-					$scope.pdf.url = "/project/#{$scope.project_id}/output/output.pdf?cache_bust=#{Date.now()}"
+					$scope.pdf.url = $scope.pdf.url + "&compileGroup=#{$scope.pdf.compileGroup}"
+				fileByPath = {}
+				for file in response.outputFiles
+					fileByPath[file.path] = file
+				if fileByPath['output.pdf']?.build?
+					build = fileByPath['output.pdf'].build
+					$scope.pdf.url = $scope.pdf.url + "&build=#{build}"
+
 				fetchLogs()
 
 			IGNORE_FILES = ["output.fls", "output.fdb_latexmk"]