diff --git a/changelog.d/fixes/9034-fix.plan.md b/changelog.d/fixes/9034-fix.plan.md
new file mode 100644
index 0000000000..49fa4b744d
--- /dev/null
+++ b/changelog.d/fixes/9034-fix.plan.md
@@ -0,0 +1 @@
+- fix(api): use configured prefix instead of raw node UUID for alias-backed model id in /v1/models (#9034)
diff --git a/src/app/api/v1/models/catalog.ts b/src/app/api/v1/models/catalog.ts
index e75517112d..128aedf3b2 100644
--- a/src/app/api/v1/models/catalog.ts
+++ b/src/app/api/v1/models/catalog.ts
@@ -1376,7 +1376,7 @@ async function buildUnifiedModelsResponseCore(
           continue;
         }
 
-        // #8958: honor the compatible-provider node prefix (as the synced/custom
+        // #8958/#9034: honor the compatible-provider node prefix (as the synced/custom
         // loops do) so an alias-backed entry publishes `prefix/model` instead of the
         // raw provider-node UUID. Without the providerIdToPrefix lookup, `alias` fell
         // through to `providerKey` (the UUID) and the dedupe below — which only checks
diff --git a/tests/unit/9034-alias-backed-prefix-id-repro.test.ts b/tests/unit/9034-alias-backed-prefix-id-repro.test.ts
new file mode 100644
index 0000000000..76188b69bd
--- /dev/null
+++ b/tests/unit/9034-alias-backed-prefix-id-repro.test.ts
@@ -0,0 +1,120 @@
+/**
+ * Regression test for #9034 — /v1/models alias-backed emission block (catalog.ts ~:1298)
+ * leaked the raw provider-node UUID as the published model `id` for alias-backed models
+ * (synced via `syncManagedAvailableModelAliases`), instead of the operator-configured
+ * prefix. The #8327 fix only covered `owned_by`; the routable model `id` was missed.
+ *
+ * Root cause: the alias-backed block builds `alias` as
+ * `providerIdToAlias[canonicalProviderId] || providerKey` and never consults
+ * `providerIdToPrefix`. For a compatible provider node, the storage prefix is the raw
+ * node UUID (managedAvailableModels.getProviderStoragePrefix()), so `providerKey` is the
+ * node UUID and the catalog re-publishes it as the public model `id` (e.g.
+ * `openai-compatible-chat-550e8400-.../kimi-k2`) instead of the configured prefix.
+ *
+ * Fix: resolve `const prefix = providerIdToPrefix[providerKey] ?? providerIdToPrefix[canonicalProviderId]`
+ * and `const alias = prefix || providerIdToAlias[canonicalProviderId] || providerKey`,
+ * plus add `!prefix` to the includeCanonical guard (mirroring synced :896 / custom :1245).
+ */
+import test from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-9034-"));
+process.env.DATA_DIR = TEST_DATA_DIR;
+
+// Type-only imports for the module shape
+type CoreModule = typeof import("../../src/lib/db/core.ts");
+type ProvidersDbModule = typeof import("../../src/lib/db/providers.ts");
+type ModelsDbModule = typeof import("../../src/lib/db/models.ts");
+type CatalogModule = typeof import("../../src/app/api/v1/models/catalog.ts");
+type ManagedAvailableModelsModule = typeof import("../../src/lib/providerModels/managedAvailableModels.ts");
+
+let core: CoreModule;
+let providersDb: ProvidersDbModule;
+let modelsDb: ModelsDbModule;
+let v1ModelsCatalog: CatalogModule;
+let managedAvailableModels: ManagedAvailableModelsModule;
+
+// A realistic provider-node id shape, matching `openai-compatible-chat-<uuid>`
+const NODE_ID = "openai-compatible-chat-550e8400-e29b-41d4-a716-446655440000";
+const UUID_SHAPE_RE = /[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/i;
+const CONFIGURED_PREFIX = "myprefix";
+const MODEL_NAME = "kimi-k2";
+
+async function resetStorage() {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+  fs.mkdirSync(TEST_DATA_DIR, { recursive: true });
+  v1ModelsCatalog.__resetCatalogBuilderRunsForTest();
+}
+
+test.before(async () => {
+  core = await import("../../src/lib/db/core.ts");
+  providersDb = await import("../../src/lib/db/providers.ts");
+  modelsDb = await import("../../src/lib/db/models.ts");
+  v1ModelsCatalog = await import("../../src/app/api/v1/models/catalog.ts");
+  managedAvailableModels = await import("../../src/lib/providerModels/managedAvailableModels.ts");
+  await resetStorage();
+});
+
+test.after(async () => {
+  if (core) core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+});
+
+test("#9034: alias-backed model id must use the configured prefix, not the raw provider-node UUID", async () => {
+  // Create an openai-compatible provider node with a configured prefix
+  await providersDb.createProviderNode({
+    id: NODE_ID,
+    type: "openai-compatible",
+    name: "test node (probe)",
+    prefix: CONFIGURED_PREFIX,
+    baseUrl: "https://proxy.example.com",
+    chatPath: "/v1/chat/completions",
+    modelsPath: "/v1/models",
+  });
+  await providersDb.createProviderConnection({
+    provider: NODE_ID,
+    authType: "apikey",
+    name: "test-conn",
+    apiKey: "sk-test",
+    isActive: true,
+    testStatus: "active",
+    providerSpecificData: {
+      baseUrl: "https://proxy.example.com",
+      chatPath: "/v1/chat/completions",
+      modelsPath: "/v1/models",
+    },
+  });
+
+  // The real producer path: syncManagedAvailableModelAliases stores aliases as
+  // `<UUID>/<modelId>` (getProviderStoragePrefix returns raw node id for compatible providers).
+  // This creates a key_value alias entry that the alias-backed block in catalog.ts reads.
+  await managedAvailableModels.syncManagedAvailableModelAliases(NODE_ID, [MODEL_NAME]);
+
+  const response = await v1ModelsCatalog.getUnifiedModelsResponse(
+    new Request("http://localhost/api/v1/models")
+  );
+  const body = (await response.json()) as { data: Array<Record<string, unknown>> };
+  const ids = body.data.map((m) => m.id as string);
+
+  assert.equal(response.status, 200);
+
+  // (a) The configured prefix must be used in the model id
+  const expectedId = `${CONFIGURED_PREFIX}/${MODEL_NAME}`;
+  assert.ok(
+    ids.includes(expectedId),
+    `expected model id "${expectedId}" to exist in /v1/models — got: ${JSON.stringify(ids)}`
+  );
+
+  // (b) No entry id should start with the raw node UUID when a prefix is configured
+  for (const id of ids) {
+    assert.equal(
+      id.startsWith(NODE_ID),
+      false,
+      `entry id "${id}" must not start with the raw provider-node UUID "${NODE_ID}" when a prefix ("${CONFIGURED_PREFIX}") is configured`
+    );
+  }
+});
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