diff --git a/.agents/skills/trogonstack-sync-upstream/SKILL.md b/.agents/skills/trogonstack-sync-upstream/SKILL.md
index cf10665816e37..10bff36022f4c 100644
--- a/.agents/skills/trogonstack-sync-upstream/SKILL.md
+++ b/.agents/skills/trogonstack-sync-upstream/SKILL.md
@@ -44,6 +44,10 @@ Default to upstream's shape and re-apply the fork's intent on top of it. Concret
 
 Record every nontrivial resolution decision as you go; each one becomes a PR body bullet.
 
+### Generated files
+
+- `apps/web/src/routeTree.gen.ts` is written by the TanStack router plugin whenever Vite runs, including the test suite in step 4. Accept git's merge result for it, and if the verification run rewrites it, commit the rewritten file. Never resolve it by hand and never restore the fork's copy to quiet a diff: the merge base then carries the stale content and every later sync keeps it, which is how the generator header went missing for a week.
+
 ### Migration rules (apps/server/src/persistence)
 
 - Upstream migrations sync as-is, keeping their own ids. `Migrations.ts` and every file under `apps/server/src/persistence/Migrations/` must stay byte-identical to upstream. If either conflicts during a sync, take upstream's side wholesale rather than hand-merging.
diff --git a/apps/web/src/routeTree.gen.ts b/apps/web/src/routeTree.gen.ts
index 74e6b71794555..55d2b4048d2a6 100644
--- a/apps/web/src/routeTree.gen.ts
+++ b/apps/web/src/routeTree.gen.ts
@@ -4,6 +4,10 @@
 
 // noinspection JSUnusedGlobalSymbols
 
+// This file was automatically generated by TanStack Router.
+// You should NOT make any changes in this file as it will be overwritten.
+// Additionally, you should also exclude this file from your linter and/or formatter to prevent it from being checked or modified.
+
 import { Route as rootRouteImport } from './routes/__root'
 import { Route as WelcomeRouteImport } from './routes/welcome'
 import { Route as UsageRouteImport } from './routes/usage'