test(ui): catch a preset spelling the same model two ways in one tier

buildPresetPrefill resolves every model reference through normalizeModelName,
so two spellings of the same model in one tier (e.g. "claude-sonnet-4-5" and
"claude-sonnet-4.5") collapse to one key. For tier_model_configs that means one
model's litellm_params silently overwrites the other's - flagged by Greptile
on #38453 (P2, confirmed real via a throwaway repro, not a regression: on the
merge base both param sets were already dropped).

Nothing else validates preset authoring, and these are trusted, checked-in
JSON, so the fix is a static test over the bundled data rather than runtime
code. Exports normalizeModelName so the test exercises the actual resolution
rule instead of a hand-rolled copy of it. Verified the test fails when a
preset is mutated to spell one model two ways, and passes clean on the real
bundled presets.

ui/litellm-dashboard/src/lib/autorouter_presets.test.ts

@@ -11,6 +11,7 @@ import {
   buildPresetPrefill,
   buildModelAvailability,
   deploymentRefsFromModelInfo,
+  normalizeModelName,
 } from "./autorouter_presets";
 import { DEFAULT_MATCH_THRESHOLD } from "@/components/add_model/SemanticKeywordMatching";
 import { DEFAULT_ESCALATION_KEYWORDS } from "@/components/add_model/EscalationKeywords";
@@ -28,6 +29,29 @@ describe("autorouter_presets", () => {
     }
   });
 
+  // buildPresetPrefill resolves every model reference through normalizeModelName, so two spellings
+  // of the same model in one tier (e.g. "claude-sonnet-4-5" and "claude-sonnet-4.5") collapse to one
+  // key. For tier_model_configs that silently drops one model's litellm_params; catch it in the
+  // bundled data itself, since nothing else validates preset authoring.
+  it("never spells the same model two ways within a single tier", () => {
+    for (const preset of getAllPresets()) {
+      const { tiers, tier_model_configs: configs } = preset.complexity_router_config;
+      for (const tier of Object.keys(tiers) as (keyof typeof tiers)[]) {
+        const fromTierList = tiers[tier] ?? [];
+        const fromConfigs = (configs?.[tier] ?? []).map((entry) => entry.model_name);
+        const names = new Set([...fromTierList, ...fromConfigs]);
+        const byNormalized = new Map<string, string[]>();
+        for (const name of names) {
+          const key = normalizeModelName(name);
+          byNormalized.set(key, [...(byNormalized.get(key) ?? []), name]);
+        }
+        for (const spellings of byNormalized.values()) {
+          expect(new Set(spellings).size, `${preset.key}.${tier}: ${spellings.join(", ")}`).toBe(1);
+        }
+      }
+    }
+  });
+
   it("resolves a preset by its stable JSON key, not its display label", () => {
     expect(getPresetByKey("anthropic_family")?.label).toBe("Anthropic Family");
     expect(getPresetByKey("does_not_exist")).toBeUndefined();

ui/litellm-dashboard/src/lib/autorouter_presets.ts

@@ -55,7 +55,7 @@ export const getRequiredModels = (
 // differing only in that separator. Canonicalizing on "-" (the presets' own convention) lets both
 // spellings match without doing anything looser - two DIFFERENT model names never collide here,
 // only the punctuation within one version number does.
-const normalizeModelName = (model: string): string => model.replace(/(\d)\.(\d)/g, "$1-$2");
+export const normalizeModelName = (model: string): string => model.replace(/(\d)\.(\d)/g, "$1-$2");
 
 export interface DeploymentModelRef {
   modelGroup: string;