diff --git a/changelog.d/fixes/11822-playground-persisted-combo-simulation.md b/changelog.d/fixes/11822-playground-persisted-combo-simulation.md
new file mode 100644
index 000000000000..7fc58cf57f86
--- /dev/null
+++ b/changelog.d/fixes/11822-playground-persisted-combo-simulation.md
@@ -0,0 +1 @@
+- Fix persisted model steps returning an error in the playground route simulator, and warn when structural steps cannot be simulated.
diff --git a/src/app/api/playground/simulate-route/route.ts b/src/app/api/playground/simulate-route/route.ts
index 184803d13ad1..993f73d2e9b6 100644
--- a/src/app/api/playground/simulate-route/route.ts
+++ b/src/app/api/playground/simulate-route/route.ts
@@ -152,7 +152,33 @@ export async function POST(request: Request) {
         errors.push(`Combo "${body.comboId}" not found.`);
         return NextResponse.json({ error: "Combo not found" }, { status: 404 });
       }
-      const targets = typeof combo.targets === "string" ? JSON.parse(combo.targets) : combo.targets;
+      const persistedSteps = Array.isArray(combo.models) ? combo.models : [];
+      const modelSteps = persistedSteps.filter(
+        (step: any) =>
+          typeof step === "string" ||
+          ((step.kind === undefined || step.kind === "model") && typeof step.model === "string")
+      );
+      const unsupportedStepCount = persistedSteps.length - modelSteps.length;
+      if (unsupportedStepCount > 0) {
+        warnings.push(
+          `Skipped ${unsupportedStepCount} unsupported persisted combo ${unsupportedStepCount === 1 ? "step" : "steps"}.`
+        );
+      }
+      const targets = modelSteps.map((step: any) => {
+        const value = typeof step === "string" ? step : step.model;
+        const separator = value.indexOf("/");
+        const parsedProvider = separator === -1 ? undefined : value.slice(0, separator);
+        const parsedModel = separator === -1 ? value : value.slice(separator + 1);
+
+        return {
+          provider:
+            typeof step === "string"
+              ? parsedProvider || "unknown"
+              : step.providerId || step.provider || parsedProvider || "unknown",
+          model: parsedModel,
+          weight: typeof step === "string" ? undefined : step.weight,
+        };
+      });
       comboInfo = { name: combo.name, strategy: combo.strategy, targets };
     } else if (body.combo) {
       comboInfo = body.combo;
@@ -172,7 +198,11 @@ export async function POST(request: Request) {
     for (let i = 0; i < comboInfo.targets.length; i++) {
       const t = comboInfo.targets[i];
       const conn = connections.find(
-        (c: any) => c.id === t.provider || c.name === t.provider || c.displayName === t.provider
+        (c: any) =>
+          c.provider === t.provider ||
+          c.id === t.provider ||
+          c.name === t.provider ||
+          c.displayName === t.provider
       );
       const cost = estimateCost(t.model, promptTokens);
       const latency = estimateLatency(t.model);
diff --git a/tests/unit/playground-simulate-route-persisted-combo.test.ts b/tests/unit/playground-simulate-route-persisted-combo.test.ts
new file mode 100644
index 000000000000..180f0793db6c
--- /dev/null
+++ b/tests/unit/playground-simulate-route-persisted-combo.test.ts
@@ -0,0 +1,104 @@
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import test from "node:test";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-playground-simulate-"));
+process.env.DATA_DIR = TEST_DATA_DIR;
+
+const core = await import("../../src/lib/db/core.ts");
+const combosDb = await import("../../src/lib/db/combos.ts");
+const providersDb = await import("../../src/lib/db/providers.ts");
+const { POST } = await import("../../src/app/api/playground/simulate-route/route.ts");
+
+let persistedComboId: string;
+
+test.beforeEach(async () => {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+  fs.mkdirSync(TEST_DATA_DIR, { recursive: true });
+  await providersDb.createProviderConnection({
+    provider: "cc",
+    authType: "no-auth",
+    name: "Claude Code",
+  });
+  await providersDb.createProviderConnection({
+    provider: "anthropic",
+    authType: "no-auth",
+    name: "Anthropic",
+  });
+  const combo = await combosDb.createCombo({
+    name: "persisted combo",
+    strategy: "priority",
+    models: [
+      { kind: "model", model: "cc/claude-opus-5", fallbackOnlyOnQuotaExhaustion: true },
+      { kind: "model", providerId: "anthropic", model: "anthropic/claude-opus-5" },
+      { kind: "combo-ref", comboName: "nested combo" },
+    ],
+  });
+  persistedComboId = combo.id;
+});
+
+test.after(() => {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+});
+
+function request(body: unknown): Request {
+  return new Request("http://localhost/api/playground/simulate-route", {
+    method: "POST",
+    headers: { "content-type": "application/json" },
+    body: JSON.stringify(body),
+  });
+}
+
+test("simulates persisted combo model steps in order", async () => {
+  const response = await POST(request({ comboId: persistedComboId, promptTokens: 500 }));
+  const body = await response.json();
+
+  assert.equal(response.status, 200);
+  assert.deepEqual(
+    body.targets.map(({ provider, model, rank }: Record<string, unknown>) => ({
+      provider,
+      model,
+      rank,
+    })),
+    [
+      { provider: "cc", model: "claude-opus-5", rank: 1 },
+      { provider: "anthropic", model: "claude-opus-5", rank: 2 },
+    ]
+  );
+  assert.deepEqual(
+    body.targets.map(({ status }: Record<string, unknown>) => status),
+    ["available", "available"]
+  );
+  assert.ok(body.warnings.includes("Skipped 1 unsupported persisted combo step."));
+  assert.ok(body.warnings.every((warning: string) => !warning.includes("not configured")));
+});
+
+test("returns 404 for a missing persisted combo", async () => {
+  const response = await POST(request({ comboId: "missing" }));
+
+  assert.equal(response.status, 404);
+  assert.deepEqual(await response.json(), { error: "Combo not found" });
+});
+
+test("preserves inline combo simulation", async () => {
+  const response = await POST(
+    request({
+      combo: {
+        name: "inline combo",
+        strategy: "priority",
+        targets: [{ provider: "cc", model: "claude-opus-5" }],
+      },
+    })
+  );
+  const body = await response.json();
+
+  assert.equal(response.status, 200);
+  assert.deepEqual(
+    body.targets.map(({ provider, model }: Record<string, unknown>) => ({ provider, model })),
+    [{ provider: "cc", model: "claude-opus-5" }]
+  );
+});