fix(webapp): logs download for buffered runs returns a placeholder line, not 404

The dashboard's "Download logs" button on a run-detail page generates
`/resources/runs/{runFriendlyId}/logs/download`. For a buffered run
(no PG row yet) the loader's `prisma.taskRun.findFirst` returned null
and the route 404'd. The customer just triggered the run and got back
its id, so a 404 here reads as "your run vanished" — when the truth
is just "the run hasn't executed, so there are no logs yet."

When the PG lookup misses, verify the entry exists in the mollifier
buffer and the requesting user belongs to its org. Then stream a
gzipped log file containing a single informational line in the same
`<timestamp> <task> <level> <message>` shape `formatRunEvent` emits
elsewhere in this route:

  2026-05-29T07:58:56.839Z hello-world INFO Run is queued, has not
  started executing yet — no logs to download.

A meaningful one-liner beats a 0-byte file when a customer is grepping
the download for a clue. The line uses INFO (not TRACE) so it doesn't
look like an execution span.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: d-cs

apps/webapp/app/routes/resources.runs.$runParam.logs.download.ts

@@ -9,6 +9,7 @@ import { formatDurationMilliseconds } from "@trigger.dev/core/v3/utils/durations
 import { getTaskEventStoreTableForRun } from "~/v3/taskEventStore.server";
 import { TaskEventKind } from "@trigger.dev/database";
 import { getEventRepositoryForStore } from "~/v3/eventRepository/index.server";
+import { getMollifierBuffer } from "~/v3/mollifier/mollifierBuffer.server";
 
 export async function loader({ params, request }: LoaderFunctionArgs) {
   const user = await requireUser(request);
@@ -30,6 +31,60 @@ export async function loader({ params, request }: LoaderFunctionArgs) {
   });
 
   if (!run || !run.organizationId) {
+    // Buffered run? It hasn't executed, so there are no events to
+    // stream — but a 404 is wrong: the run does exist, the customer's
+    // "Download logs" button on the run-detail page generates this
+    // exact URL, and a 404 reads as "your run vanished" rather than
+    // "no logs yet". Verify the entry exists in the buffer (with the
+    // user as a member of the entry's org), and if so stream a single
+    // informational line in the same `<timestamp> <task> <level>
+    // <message>` shape `formatRunEvent` uses below — so a downstream
+    // log viewer / grep over the downloaded file produces a
+    // meaningful explanation, not a 0-byte mystery.
+    const buffer = getMollifierBuffer();
+    if (buffer) {
+      const entry = await buffer.getEntry(parsedParams.runParam);
+      if (entry) {
+        const member = await prisma.orgMember.findFirst({
+          where: { userId: user.id, organizationId: entry.orgId },
+          select: { id: true },
+        });
+        if (member) {
+          let taskIdentifier: string | undefined;
+          try {
+            const snapshot = JSON.parse(entry.payload) as { taskIdentifier?: unknown };
+            if (typeof snapshot.taskIdentifier === "string") {
+              taskIdentifier = snapshot.taskIdentifier;
+            }
+          } catch {
+            // Fall through — taskIdentifier stays undefined.
+          }
+          const placeholderParts = [
+            entry.createdAt.toISOString(),
+            ...(taskIdentifier ? [taskIdentifier] : []),
+            "INFO",
+            "Run is queued, has not started executing yet — no logs to download.",
+          ];
+          const placeholder = placeholderParts.join(" ") + "\n";
+          const placeholderReadable = new Readable({
+            read() {
+              this.push(placeholder);
+              this.push(null);
+            },
+          });
+          const gzipStream = createGzip();
+          const compressed = placeholderReadable.pipe(gzipStream);
+          return new Response(compressed as any, {
+            status: 200,
+            headers: {
+              "Content-Type": "application/octet-stream",
+              "Content-Disposition": `attachment; filename="${parsedParams.runParam}.log"`,
+              "Content-Encoding": "gzip",
+            },
+          });
+        }
+      }
+    }
     return new Response("Not found", { status: 404 });
   }