From 47e52cf2244deee56ed1f462d208e4c77edfab6c Mon Sep 17 00:00:00 2001
From: Dean Rie <deanalexrie@gmail.com>
Date: Sun, 25 Oct 2026 20:50:56 +0300
Subject: [PATCH] fix(moderation): refuse a re-scan while one is queued or
 running, from every entry point

---
 apps/cursor/src/lib/mcp/tools.ts          | 22 ++++++-----------
 apps/cursor/src/lib/plugins/moderation.ts | 29 +++++++++++++++++++++++
 2 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/apps/cursor/src/lib/mcp/tools.ts b/apps/cursor/src/lib/mcp/tools.ts
index 8fad1662..0f026654 100644
--- a/apps/cursor/src/lib/mcp/tools.ts
+++ b/apps/cursor/src/lib/mcp/tools.ts
@@ -39,9 +39,6 @@ const UNTRUSTED_NOTE =
 const UUID_RE =
   /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
 
-// Matches the stuck-scan threshold in getStuckScans(): older pending/scanning
-// rows are treated as stuck and may be re-scanned.
-const SCAN_IN_PROGRESS_MS = 15 * 60 * 1000;
 const MAX_COMPONENT_CONTENT_CHARS = 4000;
 const MAX_SUMMARY_CHARS = 500;
 
@@ -534,20 +531,15 @@ export function registerModerationTools(server: McpServer) {
       annotations: { ...write, idempotentHint: false },
     },
     adminTool(async ({ plugin }, admin) => {
-      const state = await getPluginModerationState(
-        await resolvePluginId(plugin),
-      );
-      const inProgress =
-        (state.scan_status === "pending" || state.scan_status === "scanning") &&
-        Date.now() - new Date(state.updated_at).getTime() < SCAN_IN_PROGRESS_MS;
-      if (inProgress) {
-        throw new ToolError(
-          `A scan for "${state.slug}" is already ${state.scan_status}. Check again in a few minutes.`,
-        );
-      }
+      // rescanPlugin refuses with a ModerationError while a scan is queued or
+      // running (same check the admin UI buttons go through); adminTool turns
+      // that into the error text.
       return changed(
         "Re-scan queued",
-        await rescanPlugin(await beginWrite(admin), state.id),
+        await rescanPlugin(
+          await beginWrite(admin),
+          await resolvePluginId(plugin),
+        ),
       );
     }),
   );
diff --git a/apps/cursor/src/lib/plugins/moderation.ts b/apps/cursor/src/lib/plugins/moderation.ts
index 920ac324..644aef6e 100644
--- a/apps/cursor/src/lib/plugins/moderation.ts
+++ b/apps/cursor/src/lib/plugins/moderation.ts
@@ -203,7 +203,36 @@ export function blockPlugin(
   );
 }
 
+/**
+ * A pending/scanning row younger than this still has a live queue message or
+ * a running worker behind it. Matches the stuck-scan threshold shared by
+ * getStuckScans() and the recover-stuck-scans cron: an older row is treated
+ * as stuck and may be re-scanned.
+ */
+export const SCAN_IN_PROGRESS_MS = 15 * 60 * 1000;
+
+export function isScanInProgress(
+  state: Pick<PluginModerationState, "scan_status" | "updated_at">,
+  now = Date.now(),
+): boolean {
+  if (state.scan_status !== "pending" && state.scan_status !== "scanning") {
+    return false;
+  }
+  return now - new Date(state.updated_at).getTime() < SCAN_IN_PROGRESS_MS;
+}
+
 export async function rescanPlugin(ctx: ModerationContext, pluginId: string) {
+  // Every re-scan entry point (admin UI buttons, MCP tool) lands here, so the
+  // in-progress check lives here too. Without it a second click while the
+  // first scan is queued or running enqueues a second message for the same
+  // plugin: two billable agent runs whose verdicts race each other.
+  const state = await getPluginModerationState(pluginId);
+  if (isScanInProgress(state)) {
+    throw new ModerationError(
+      `A scan for "${state.slug}" is already ${state.scan_status}. Check again in a few minutes.`,
+    );
+  }
+
   // The status reset must reach cached readers (detail banner, leaderboard)
   // before enqueueing, so a queue failure can't leave cached views showing a
   // stale status while the row is already pending. The drain route only