diff --git a/src/commands/doctor-synthetic-allowlist.test.ts b/src/commands/doctor-synthetic-allowlist.test.ts
new file mode 100644
index 00000000000..a5a66717729
--- /dev/null
+++ b/src/commands/doctor-synthetic-allowlist.test.ts
@@ -0,0 +1,131 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("../agents/model-catalog.js", () => ({
+  loadModelCatalog: vi.fn(),
+}));
+vi.mock("../agents/model-selection.js", async (importOriginal) => {
+  const actual = await importOriginal();
+  return { ...actual, buildAllowedModelSet: vi.fn() };
+});
+vi.mock("../terminal/note.js", () => ({ note: vi.fn() }));
+
+import { loadModelCatalog } from "../agents/model-catalog.js";
+import { buildAllowedModelSet } from "../agents/model-selection.js";
+import type { OpenClawConfig } from "../config/config.js";
+import { note } from "../terminal/note.js";
+import { noteSyntheticAllowlistGaps } from "./doctor-synthetic-allowlist.js";
+
+const mockLoadModelCatalog = vi.mocked(loadModelCatalog);
+const mockBuildAllowedModelSet = vi.mocked(buildAllowedModelSet);
+const mockNote = vi.mocked(note);
+
+function makeCfg(models?: Record<string, unknown>): OpenClawConfig {
+  return {
+    agents: { defaults: { models: models as OpenClawConfig["agents"]["defaults"]["models"] } },
+  } as OpenClawConfig;
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+});
+
+describe("noteSyntheticAllowlistGaps", () => {
+  it("skips when no allowlist is configured", async () => {
+    await noteSyntheticAllowlistGaps(makeCfg());
+    expect(mockLoadModelCatalog).not.toHaveBeenCalled();
+    expect(mockNote).not.toHaveBeenCalled();
+  });
+
+  it("skips when allowlist is empty", async () => {
+    await noteSyntheticAllowlistGaps(makeCfg({}));
+    expect(mockLoadModelCatalog).not.toHaveBeenCalled();
+    expect(mockNote).not.toHaveBeenCalled();
+  });
+
+  it("skips when allowAny is true", async () => {
+    const catalog = [{ id: "gpt-5.4", name: "gpt-5.4", provider: "openai" }];
+    mockLoadModelCatalog.mockResolvedValue(catalog);
+    mockBuildAllowedModelSet.mockReturnValue({
+      allowAny: true,
+      allowedCatalog: catalog,
+      allowedKeys: new Set(["openai/gpt-5.4"]),
+    });
+
+    await noteSyntheticAllowlistGaps(makeCfg({ "anthropic/claude-opus-4-6": {} }));
+    expect(mockNote).not.toHaveBeenCalled();
+  });
+
+  it("does not warn when all synthetic models are allowlisted", async () => {
+    const catalog = [
+      { id: "gpt-5.4", name: "gpt-5.4", provider: "openai-codex" },
+      { id: "claude-opus-4-6", name: "Claude Opus 4.6", provider: "anthropic" },
+    ];
+    mockLoadModelCatalog.mockResolvedValue(catalog);
+    mockBuildAllowedModelSet.mockReturnValue({
+      allowAny: false,
+      allowedCatalog: catalog,
+      allowedKeys: new Set(["openai-codex/gpt-5.4", "anthropic/claude-opus-4-6"]),
+    });
+
+    await noteSyntheticAllowlistGaps(
+      makeCfg({ "openai-codex/gpt-5.4": {}, "anthropic/claude-opus-4-6": {} }),
+    );
+    expect(mockNote).not.toHaveBeenCalled();
+  });
+
+  it("warns about synthetic models missing from allowlist", async () => {
+    const catalog = [
+      { id: "gpt-5.4", name: "gpt-5.4", provider: "openai-codex" },
+      { id: "gpt-5.4", name: "gpt-5.4", provider: "openai" },
+      { id: "gpt-5.4-pro", name: "gpt-5.4-pro", provider: "openai" },
+      { id: "claude-opus-4-6", name: "Claude Opus 4.6", provider: "anthropic" },
+    ];
+    mockLoadModelCatalog.mockResolvedValue(catalog);
+    mockBuildAllowedModelSet.mockReturnValue({
+      allowAny: false,
+      allowedCatalog: [catalog[0], catalog[3]],
+      allowedKeys: new Set(["openai-codex/gpt-5.4", "anthropic/claude-opus-4-6"]),
+    });
+
+    await noteSyntheticAllowlistGaps(
+      makeCfg({ "openai-codex/gpt-5.4": {}, "anthropic/claude-opus-4-6": {} }),
+    );
+
+    expect(mockNote).toHaveBeenCalledTimes(1);
+    const noteText = mockNote.mock.calls[0][0];
+    expect(noteText).toContain("2 synthetic model");
+    expect(noteText).toContain("openai/gpt-5.4");
+    expect(noteText).toContain("openai/gpt-5.4-pro");
+  });
+
+  it("ignores non-synthetic providers", async () => {
+    const catalog = [
+      { id: "gemini-3-flash", name: "Gemini 3 Flash", provider: "google" },
+      { id: "claude-opus-4-6", name: "Claude Opus 4.6", provider: "anthropic" },
+    ];
+    mockLoadModelCatalog.mockResolvedValue(catalog);
+    mockBuildAllowedModelSet.mockReturnValue({
+      allowAny: false,
+      allowedCatalog: [catalog[1]],
+      allowedKeys: new Set(["anthropic/claude-opus-4-6"]),
+    });
+
+    await noteSyntheticAllowlistGaps(makeCfg({ "anthropic/claude-opus-4-6": {} }));
+    expect(mockNote).not.toHaveBeenCalled();
+  });
+
+  it("handles single synthetic gap with correct grammar", async () => {
+    const catalog = [{ id: "gpt-5.4", name: "gpt-5.4", provider: "openai" }];
+    mockLoadModelCatalog.mockResolvedValue(catalog);
+    mockBuildAllowedModelSet.mockReturnValue({
+      allowAny: false,
+      allowedCatalog: [],
+      allowedKeys: new Set(["anthropic/claude-opus-4-6"]),
+    });
+
+    await noteSyntheticAllowlistGaps(makeCfg({ "anthropic/claude-opus-4-6": {} }));
+    const noteText = mockNote.mock.calls[0][0];
+    expect(noteText).toContain("1 synthetic model available");
+    expect(noteText).not.toContain("models available");
+  });
+});
diff --git a/src/commands/doctor-synthetic-allowlist.ts b/src/commands/doctor-synthetic-allowlist.ts
new file mode 100644
index 00000000000..9c01a9b2a21
--- /dev/null
+++ b/src/commands/doctor-synthetic-allowlist.ts
@@ -0,0 +1,73 @@
+import { DEFAULT_MODEL, DEFAULT_PROVIDER } from "../agents/defaults.js";
+import { loadModelCatalog } from "../agents/model-catalog.js";
+import { buildAllowedModelSet, modelKey } from "../agents/model-selection.js";
+import { formatCliCommand } from "../cli/command-format.js";
+import type { OpenClawConfig } from "../config/config.js";
+import { note } from "../terminal/note.js";
+
+/**
+ * The exact provider/id pairs created by `applySyntheticCatalogFallbacks()`.
+ * Only these are checked to avoid false positives from real catalog models
+ * that happen to share the same provider.
+ */
+const SYNTHETIC_FALLBACK_KEYS = new Set([
+  "openai/gpt-5.4",
+  "openai/gpt-5.4-pro",
+  "openai-codex/gpt-5.4",
+  "openai-codex/gpt-5.3-codex-spark",
+]);
+
+/**
+ * Warn when synthetic catalog fallback models are present in the runtime
+ * catalog but missing from the operator's explicit model allowlist.
+ *
+ * Skips the check when no allowlist is configured (empty
+ * `agents.defaults.models` means all models are allowed).
+ *
+ * @see https://github.com/openclaw/openclaw/issues/39992
+ */
+export async function noteSyntheticAllowlistGaps(cfg: OpenClawConfig): Promise<void> {
+  const modelsConfig = cfg.agents?.defaults?.models;
+  if (!modelsConfig || Object.keys(modelsConfig).length === 0) {
+    return;
+  }
+
+  const catalog = await loadModelCatalog({ config: cfg });
+  const { allowAny, allowedKeys } = buildAllowedModelSet({
+    cfg,
+    catalog,
+    defaultProvider: DEFAULT_PROVIDER,
+    defaultModel: DEFAULT_MODEL,
+  });
+  if (allowAny) {
+    return; // all models are allowed; nothing to warn about
+  }
+
+  const gaps: Array<{ provider: string; id: string }> = [];
+  for (const entry of catalog) {
+    const key = modelKey(entry.provider, entry.id);
+    if (!SYNTHETIC_FALLBACK_KEYS.has(key)) {
+      continue;
+    }
+    if (!allowedKeys.has(key)) {
+      gaps.push(entry);
+    }
+  }
+
+  if (gaps.length === 0) {
+    return;
+  }
+
+  const lines = [
+    `${gaps.length} synthetic model${gaps.length === 1 ? "" : "s"} available but not in your allowlist:`,
+  ];
+  for (const entry of gaps) {
+    lines.push(`  - ${modelKey(entry.provider, entry.id)}`);
+  }
+  lines.push(
+    `To add: ${formatCliCommand("openclaw config set agents.defaults.models.<provider>/<model> '{}'")}`,
+    `Or edit the config file directly: ${formatCliCommand("openclaw config file")}`,
+    "(Models are functional but hidden from agents until allowlisted)",
+  );
+  note(lines.join("\n"), "Synthetic model allowlist");
+}
diff --git a/src/commands/doctor.ts b/src/commands/doctor.ts
index bdde2781ff9..41b20dee038 100644
--- a/src/commands/doctor.ts
+++ b/src/commands/doctor.ts
@@ -55,6 +55,7 @@ import {
   detectLegacyStateMigrations,
   runLegacyStateMigrations,
 } from "./doctor-state-migrations.js";
+import { noteSyntheticAllowlistGaps } from "./doctor-synthetic-allowlist.js";
 import { maybeRepairUiProtocolFreshness } from "./doctor-ui.js";
 import { maybeOfferUpdateBeforeDoctor } from "./doctor-update.js";
 import { noteWorkspaceStatus } from "./doctor-workspace-status.js";
@@ -306,6 +307,7 @@ export async function doctorCommand(
   }
 
   noteWorkspaceStatus(cfg);
+  await noteSyntheticAllowlistGaps(cfg);
   await noteBootstrapFileSize(cfg);
 
   // Check and fix shell completion