fix: resolve file library Open File bug, upload reliability, and SSE proxy timeouts (#203)

The Open File button in the Files section did nothing due to a race
condition where the home page reset the file store on mount before files
from handleOpenFile could render. Upload on the files page used fetch
with no timeout, progress, or retry, causing silent failures on mobile
and slow connections. SSE connections for job progress had no keepalive
pings, allowing reverse proxies to kill idle streams.

apps/api/src/routes/progress.ts

@@ -237,11 +237,22 @@ export async function registerProgressRoutes(app: FastifyInstance): Promise<void
         reply.raw.write(`data: ${JSON.stringify(data)}\n\n`);
       };
 
+      // Send keepalive comments every 20s to prevent reverse proxies
+      // (Caddy, Nginx, ALBs) from killing idle SSE connections.
+      const keepaliveInterval = setInterval(() => {
+        try {
+          reply.raw.write(": keepalive\n\n");
+        } catch {
+          clearInterval(keepaliveInterval);
+        }
+      }, 20_000);
+
       // If the job already has progress, send it immediately
       const existing = jobProgressStore.get(jobId);
       if (existing) {
         sendEvent({ ...existing, type: "batch" });
         if (existing.status === "completed" || existing.status === "failed") {
+          clearInterval(keepaliveInterval);
           reply.raw.end();
           return;
         }
@@ -250,6 +261,7 @@ export async function registerProgressRoutes(app: FastifyInstance): Promise<void
       const existingSingle = singleFileCompletions.get(jobId);
       if (existingSingle) {
         sendEvent(existingSingle);
+        clearInterval(keepaliveInterval);
         reply.raw.end();
         return;
       }
@@ -268,6 +280,7 @@ export async function registerProgressRoutes(app: FastifyInstance): Promise<void
           ("phase" in data && (data.phase === "complete" || data.phase === "failed"))
         ) {
           ended = true;
+          clearInterval(keepaliveInterval);
           const subs = listeners.get(jobId);
           if (subs) {
             subs.delete(callback);
@@ -281,6 +294,7 @@ export async function registerProgressRoutes(app: FastifyInstance): Promise<void
 
       // Clean up on client disconnect
       request.raw.on("close", () => {
+        clearInterval(keepaliveInterval);
         const subs = listeners.get(jobId);
         if (subs) {
           subs.delete(callback);