diff --git a/ui/litellm-dashboard/src/components/add_model/KeywordTierRules.tsx b/ui/litellm-dashboard/src/components/add_model/KeywordTierRules.tsx
index b5291a34cb6..0b47bc8500a 100644
--- a/ui/litellm-dashboard/src/components/add_model/KeywordTierRules.tsx
+++ b/ui/litellm-dashboard/src/components/add_model/KeywordTierRules.tsx
@@ -14,7 +14,8 @@ export type ComplexityTier = "SIMPLE" | "MEDIUM" | "COMPLEX" | "REASONING";
 export interface KeywordTierRule {
   id: string;
   keywords: string[];
-  tier: ComplexityTier;
+  /** A built-in tier name, or with a custom tier set, one of the defined tier names. */
+  tier: string;
 }
 
 interface KeywordTierRulesProps {
@@ -99,7 +100,7 @@ const KeywordTierRules: React.FC<KeywordTierRulesProps> = ({ rules, onChange, ti
                     <Select
                       items={tierOptions(tierLabels)}
                       value={rule.tier}
-                      onValueChange={(tier: ComplexityTier | null) => tier && updateRule(rule.id, { tier })}
+                      onValueChange={(tier: string | null) => tier && updateRule(rule.id, { tier })}
                     >
                       <SelectTrigger aria-label={`Route keyword rule ${index + 1} to tier`} className="w-full">
                         <SelectValue />
diff --git a/ui/litellm-dashboard/src/components/add_model/complexity_router_keywords.test.ts b/ui/litellm-dashboard/src/components/add_model/complexity_router_keywords.test.ts
new file mode 100644
index 00000000000..bc9b9ee608d
--- /dev/null
+++ b/ui/litellm-dashboard/src/components/add_model/complexity_router_keywords.test.ts
@@ -0,0 +1,25 @@
+import { describe, expect, it } from "vitest";
+
+import { hydrateKeywordTierRules, serializeKeywordTierRules } from "./complexity_router_keywords";
+
+describe("hydrateKeywordTierRules", () => {
+  it("keeps a rule whose tier is operator-defined instead of silently deleting it on edit", () => {
+    const stored = [
+      { keywords: ["invoice"], tier: "MEDIUM" },
+      { keywords: ["pentest", "vulnerability"], tier: "SECURITY_REVIEW" },
+    ];
+    expect(hydrateKeywordTierRules(stored)).toEqual([
+      { id: "stored-0", keywords: ["invoice"], tier: "MEDIUM" },
+      { id: "stored-1", keywords: ["pentest", "vulnerability"], tier: "SECURITY_REVIEW" },
+    ]);
+  });
+
+  it("round-trips through serialize without loss", () => {
+    const stored = [{ keywords: ["pentest"], tier: "SECURITY_REVIEW" }];
+    expect(serializeKeywordTierRules(hydrateKeywordTierRules(stored))).toEqual(stored);
+  });
+
+  it("still drops rows that are not rules at all", () => {
+    expect(hydrateKeywordTierRules([{ keywords: [], tier: "MEDIUM" }, { keywords: ["x"] }, "junk", null])).toEqual([]);
+  });
+});
diff --git a/ui/litellm-dashboard/src/components/add_model/complexity_router_keywords.ts b/ui/litellm-dashboard/src/components/add_model/complexity_router_keywords.ts
index 6fe93cddae3..84ccc7c81ef 100644
--- a/ui/litellm-dashboard/src/components/add_model/complexity_router_keywords.ts
+++ b/ui/litellm-dashboard/src/components/add_model/complexity_router_keywords.ts
@@ -1,18 +1,18 @@
-import { ComplexityTier, KeywordTierRule } from "./KeywordTierRules";
+import { KeywordTierRule } from "./KeywordTierRules";
 
 /**
  * Stored shape of a keyword tier rule inside `complexity_router_config`. The UI's
  * KeywordTierRule carries an extra `id` used only as a React key, so it is stripped on the
  * way out and synthesized on the way back in. Both the create form and the edit modal go
- * through here so the two directions cannot drift.
+ * through here so the two directions cannot drift. The tier is any active tier name: a
+ * built-in one, or with tier_definitions, an operator-defined one, so hydration must not
+ * filter on the built-in set or an edit would silently delete a custom tier's rules.
  */
 export interface StoredKeywordTierRule {
   keywords: string[];
-  tier: ComplexityTier;
+  tier: string;
 }
 
-const TIERS: ReadonlySet<string> = new Set<ComplexityTier>(["SIMPLE", "MEDIUM", "COMPLEX", "REASONING"]);
-
 const asKeywords = (value: unknown): string[] =>
   Array.isArray(value)
     ? value.filter((keyword): keyword is string => typeof keyword === "string").map((keyword) => keyword.trim())
@@ -40,7 +40,7 @@ export const hydrateKeywordTierRules = (value: unknown): KeywordTierRule[] => {
     const record = entry as Record<string, unknown>;
     const keywords = asKeywords(record.keywords).filter(Boolean);
     const tier = record.tier;
-    if (keywords.length === 0 || typeof tier !== "string" || !TIERS.has(tier)) return [];
-    return [{ id: `stored-${index}`, keywords, tier: tier as ComplexityTier }];
+    if (keywords.length === 0 || typeof tier !== "string" || !tier.trim()) return [];
+    return [{ id: `stored-${index}`, keywords, tier }];
   });
 };