fix: use two-pass validation in settings PUT to prevent partial writes

Validation now runs on all entries before any database writes.
Previously, clean entries could be written before a later malicious
entry triggered a 400 response.

apps/api/src/routes/settings.ts

@@ -43,8 +43,8 @@ export async function settingsRoutes(app: FastifyInstance): Promise<void> {
       });
     }
 
-    const now = new Date();
-    let updatedCount = 0;
+    // Pass 1: validate all entries before writing any
+    const entries: Array<{ key: string; strValue: string }> = [];
 
     for (const [key, value] of Object.entries(body)) {
       if (typeof key !== "string" || key.length === 0) continue;
@@ -58,6 +58,13 @@ export async function settingsRoutes(app: FastifyInstance): Promise<void> {
         });
       }
 
+      entries.push({ key, strValue });
+    }
+
+    // Pass 2: write all entries now that all have passed validation
+    const now = new Date();
+
+    for (const { key, strValue } of entries) {
       // Upsert: insert or update on conflict
       const existing = db.select().from(schema.settings).where(eq(schema.settings.key, key)).get();
 
@@ -69,11 +76,9 @@ export async function settingsRoutes(app: FastifyInstance): Promise<void> {
       } else {
         db.insert(schema.settings).values({ key, value: strValue }).run();
       }
-
-      updatedCount++;
     }
 
-    return reply.send({ ok: true, updatedCount });
+    return reply.send({ ok: true, updatedCount: entries.length });
   });
 
   // GET /api/v1/settings/:key — Get a specific setting

tests/integration/api.test.ts

@@ -1420,6 +1420,30 @@ describe("Settings", () => {
       expect(body.code).toBe("VALIDATION_ERROR");
     });
 
+    it("does not partially write entries when a later entry contains HTML tags", async () => {
+      const cleanKey = `atomicity_test_clean_${Date.now()}`;
+      const res = await app.inject({
+        method: "PUT",
+        url: "/api/v1/settings",
+        headers: { authorization: `Bearer ${adminToken}` },
+        payload: {
+          [cleanKey]: "safe_value",
+          "<script>xss</script>": "evil",
+        },
+      });
+      expect(res.statusCode).toBe(400);
+      const body = JSON.parse(res.body);
+      expect(body.code).toBe("VALIDATION_ERROR");
+
+      // The clean entry must NOT have been written
+      const getRes = await app.inject({
+        method: "GET",
+        url: `/api/v1/settings/${cleanKey}`,
+        headers: { authorization: `Bearer ${adminToken}` },
+      });
+      expect(getRes.statusCode).toBe(404);
+    });
+
     it("allows normal setting values without HTML", async () => {
       const res = await app.inject({
         method: "PUT",