diff --git a/packages/typegen/skills/getting-started/SKILL.md b/packages/typegen/skills/getting-started/SKILL.md
index 4eda27f7..7ce4d2b8 100644
--- a/packages/typegen/skills/getting-started/SKILL.md
+++ b/packages/typegen/skills/getting-started/SKILL.md
@@ -193,7 +193,7 @@ For WebViewer apps running inside FileMaker, you can use FM HTTP mode to generat
 
 **Prerequisites:**
 - FM HTTP daemon installed and running (`curl http://127.0.0.1:1365/health`)
-- FileMaker file open locally with "Connect to MCP" script run
+- FileMaker file reachable via the FM HTTP `connectedFiles` endpoint. The most common setup is to open the file locally and run a script such as "Connect to MCP", but the script name may differ in your solution as long as it establishes the bridge.
 
 1. Install packages:
 
diff --git a/packages/webviewer/package.json b/packages/webviewer/package.json
index f2936e99..a19561b5 100644
--- a/packages/webviewer/package.json
+++ b/packages/webviewer/package.json
@@ -31,6 +31,16 @@
         "default": "./dist/cjs/adapter.cjs"
       }
     },
+    "./vite-plugins": {
+      "import": {
+        "types": "./dist/esm/vite-plugins.d.ts",
+        "default": "./dist/esm/vite-plugins.js"
+      },
+      "require": {
+        "types": "./dist/cjs/vite-plugins.d.cts",
+        "default": "./dist/cjs/vite-plugins.cjs"
+      }
+    },
     "./package.json": "./package.json"
   },
   "dependencies": {
@@ -47,12 +57,14 @@
     "knip": "^5.80.2",
     "publint": "^0.3.16",
     "typescript": "^5.9.3",
-    "vite": "^6.4.1"
+    "vite": "^6.4.1",
+    "vitest": "^4.0.17"
   },
   "publishConfig": {
     "access": "public"
   },
   "scripts": {
+    "test": "vitest run",
     "typecheck": "tsc --noEmit",
     "prepublishOnly": "tsc",
     "build": "tsc && vite build && publint --strict",
diff --git a/packages/webviewer/src/fm-bridge.ts b/packages/webviewer/src/fm-bridge.ts
new file mode 100644
index 00000000..b9cdf9db
--- /dev/null
+++ b/packages/webviewer/src/fm-bridge.ts
@@ -0,0 +1,155 @@
+import type { HtmlTagDescriptor, Plugin } from "vite";
+
+const TRAILING_SLASH_PATTERN = /\/$/;
+const CONNECTED_FILES_TIMEOUT_MS = 5000;
+
+export interface FmBridgeOptions {
+  fileName?: string;
+  fmHttpBaseUrl?: string;
+  wsUrl?: string;
+  debug?: boolean;
+}
+
+export const defaultFmHttpBaseUrl = "http://localhost:1365";
+export const defaultWsUrl = "ws://localhost:1365/ws";
+
+export const trimToNull = (value: unknown): string | null => {
+  if (typeof value !== "string") {
+    return null;
+  }
+
+  const trimmed = value.trim();
+  return trimmed.length > 0 ? trimmed : null;
+};
+
+export const normalizeBaseUrl = (value: string): string => value.replace(TRAILING_SLASH_PATTERN, "");
+
+export const resolveWsUrl = (options: Pick<FmBridgeOptions, "fmHttpBaseUrl" | "wsUrl">): string => {
+  const explicitWsUrl = trimToNull(options.wsUrl);
+  if (explicitWsUrl) {
+    return explicitWsUrl;
+  }
+
+  const baseUrl = normalizeBaseUrl(trimToNull(options.fmHttpBaseUrl) ?? defaultFmHttpBaseUrl);
+
+  try {
+    const parsed = new URL(baseUrl);
+    const wsProtocol = parsed.protocol === "https:" ? "wss:" : "ws:";
+    return `${wsProtocol}//${parsed.host}/ws`;
+  } catch {
+    return defaultWsUrl;
+  }
+};
+
+export const discoverConnectedFileName = async (baseUrl: string): Promise<string> => {
+  const connectedFilesUrl = `${normalizeBaseUrl(baseUrl)}/connectedFiles`;
+  const controller = new AbortController();
+  const timeoutId = setTimeout(() => {
+    controller.abort();
+  }, CONNECTED_FILES_TIMEOUT_MS);
+  const reachabilityErrorMessage = `fmBridge could not reach ${connectedFilesUrl}. Start fm-http and connect a FileMaker webviewer.`;
+
+  let response: Response;
+  try {
+    response = await fetch(connectedFilesUrl, {
+      signal: controller.signal,
+    });
+  } catch (error) {
+    throw new Error(reachabilityErrorMessage, {
+      cause: error,
+    });
+  } finally {
+    clearTimeout(timeoutId);
+  }
+
+  if (!response.ok) {
+    throw new Error(
+      `fmBridge received HTTP ${response.status} from ${connectedFilesUrl}. Ensure fm-http is healthy and reachable.`,
+    );
+  }
+
+  const payload = (await response.json()) as unknown;
+  if (!Array.isArray(payload)) {
+    throw new Error(`fmBridge expected an array response from ${connectedFilesUrl}.`);
+  }
+
+  const firstFileName = payload.find((entry): entry is string => typeof entry === "string" && entry.trim().length > 0);
+
+  if (!firstFileName) {
+    throw new Error(
+      `fmBridge found no connected FileMaker files at ${connectedFilesUrl}. Open FileMaker and load /webviewer?fileName=YourFile.`,
+    );
+  }
+
+  return firstFileName;
+};
+
+export const buildMockScriptTag = (options: {
+  baseUrl: string;
+  fileName: string | null;
+  wsUrl: string;
+  debug: boolean;
+}): HtmlTagDescriptor | null => {
+  if (!options.fileName) {
+    return null;
+  }
+
+  const scriptUrl = new URL(`${normalizeBaseUrl(options.baseUrl)}/fm-mock.js`);
+  scriptUrl.searchParams.set("fileName", options.fileName);
+  scriptUrl.searchParams.set("wsUrl", options.wsUrl);
+
+  if (options.debug) {
+    scriptUrl.searchParams.set("debug", "true");
+  }
+
+  return {
+    tag: "script",
+    attrs: { src: scriptUrl.toString() },
+    injectTo: "head-prepend",
+  };
+};
+
+export const fmBridge = (options: FmBridgeOptions = {}): Plugin => {
+  const baseUrl = trimToNull(options.fmHttpBaseUrl) ?? defaultFmHttpBaseUrl;
+  const wsUrl = resolveWsUrl(options);
+  const debug = options.debug === true;
+  let resolvedFileName: string | null = trimToNull(options.fileName);
+  let isServeMode = true;
+
+  return {
+    name: "proofkit-fm-bridge",
+    apply(_config, { command }) {
+      isServeMode = command === "serve";
+      return isServeMode;
+    },
+    async configureServer() {
+      if (!isServeMode) {
+        return;
+      }
+
+      if (resolvedFileName) {
+        return;
+      }
+
+      resolvedFileName = await discoverConnectedFileName(baseUrl);
+    },
+    async transformIndexHtml() {
+      if (!isServeMode) {
+        return;
+      }
+
+      if (!resolvedFileName) {
+        resolvedFileName = await discoverConnectedFileName(baseUrl);
+      }
+
+      const tag = buildMockScriptTag({
+        baseUrl,
+        fileName: resolvedFileName,
+        wsUrl,
+        debug,
+      });
+
+      return tag ? [tag] : undefined;
+    },
+  };
+};
diff --git a/packages/webviewer/src/vite-plugins.ts b/packages/webviewer/src/vite-plugins.ts
new file mode 100644
index 00000000..a57fade0
--- /dev/null
+++ b/packages/webviewer/src/vite-plugins.ts
@@ -0,0 +1,6 @@
+import type { FmBridgeOptions as InternalFmBridgeOptions } from "./fm-bridge.js";
+import { fmBridge as createFmBridge } from "./fm-bridge.js";
+
+export interface FmBridgeOptions extends InternalFmBridgeOptions {}
+
+export const fmBridge = createFmBridge;
diff --git a/packages/webviewer/tests/vite-plugins.test.ts b/packages/webviewer/tests/vite-plugins.test.ts
new file mode 100644
index 00000000..eda68109
--- /dev/null
+++ b/packages/webviewer/tests/vite-plugins.test.ts
@@ -0,0 +1,203 @@
+import type { HtmlTagDescriptor } from "vite";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import {
+  buildMockScriptTag,
+  defaultWsUrl,
+  discoverConnectedFileName,
+  fmBridge,
+  resolveWsUrl,
+} from "../src/fm-bridge.ts";
+
+describe("resolveWsUrl", () => {
+  it("prefers an explicit websocket URL", () => {
+    expect(
+      resolveWsUrl({
+        fmHttpBaseUrl: "http://localhost:1365",
+        wsUrl: "ws://example.test/custom",
+      }),
+    ).toBe("ws://example.test/custom");
+  });
+
+  it("derives the websocket URL from the HTTP base URL", () => {
+    expect(
+      resolveWsUrl({
+        fmHttpBaseUrl: "https://example.test:9999/",
+      }),
+    ).toBe("wss://example.test:9999/ws");
+  });
+
+  it("falls back to the default websocket URL for invalid base URLs", () => {
+    expect(
+      resolveWsUrl({
+        fmHttpBaseUrl: "not a url",
+      }),
+    ).toBe(defaultWsUrl);
+  });
+});
+
+describe("buildMockScriptTag", () => {
+  it("builds the fm-mock script tag with required query params", () => {
+    const tag = buildMockScriptTag({
+      baseUrl: "http://localhost:1365/",
+      fileName: "Contacts",
+      wsUrl: "ws://localhost:1365/ws",
+      debug: true,
+    });
+
+    expect(tag).toEqual({
+      tag: "script",
+      attrs: {
+        src: "http://localhost:1365/fm-mock.js?fileName=Contacts&wsUrl=ws%3A%2F%2Flocalhost%3A1365%2Fws&debug=true",
+      },
+      injectTo: "head-prepend",
+    } satisfies HtmlTagDescriptor);
+  });
+});
+
+describe("discoverConnectedFileName", () => {
+  const originalFetch = globalThis.fetch;
+
+  beforeEach(() => {
+    globalThis.fetch = vi.fn();
+  });
+
+  afterEach(() => {
+    globalThis.fetch = originalFetch;
+  });
+
+  it("returns the first non-empty connected file name", async () => {
+    vi.mocked(globalThis.fetch).mockResolvedValue(
+      new Response(JSON.stringify(["", "Contacts", "Invoices"]), {
+        status: 200,
+        headers: { "Content-Type": "application/json" },
+      }),
+    );
+
+    await expect(discoverConnectedFileName("http://localhost:1365")).resolves.toBe("Contacts");
+    expect(globalThis.fetch).toHaveBeenCalledWith(
+      "http://localhost:1365/connectedFiles",
+      expect.objectContaining({ signal: expect.any(AbortSignal) }),
+    );
+  });
+
+  it("aborts stalled requests with the standard reachability error", async () => {
+    vi.useFakeTimers();
+
+    try {
+      const abortError = new DOMException("The operation was aborted.", "AbortError");
+      vi.mocked(globalThis.fetch).mockImplementation(
+        (_input, init) =>
+          new Promise((_resolve, reject) => {
+            init?.signal?.addEventListener("abort", () => {
+              reject(abortError);
+            });
+          }),
+      );
+
+      const pendingRequest = discoverConnectedFileName("http://localhost:1365");
+      const pendingExpectation = expect(pendingRequest).rejects.toMatchObject({
+        cause: abortError,
+        message:
+          "fmBridge could not reach http://localhost:1365/connectedFiles. Start fm-http and connect a FileMaker webviewer.",
+      });
+
+      await vi.advanceTimersByTimeAsync(5000);
+      await pendingExpectation;
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it("rejects non-ok HTTP responses", async () => {
+    vi.mocked(globalThis.fetch).mockResolvedValue(new Response("nope", { status: 503 }));
+
+    await expect(discoverConnectedFileName("http://localhost:1365")).rejects.toThrow(
+      "fmBridge received HTTP 503 from http://localhost:1365/connectedFiles. Ensure fm-http is healthy and reachable.",
+    );
+  });
+
+  it("rejects invalid payloads", async () => {
+    vi.mocked(globalThis.fetch).mockResolvedValue(
+      new Response(JSON.stringify({ fileName: "Contacts" }), {
+        status: 200,
+        headers: { "Content-Type": "application/json" },
+      }),
+    );
+
+    await expect(discoverConnectedFileName("http://localhost:1365")).rejects.toThrow(
+      "fmBridge expected an array response from http://localhost:1365/connectedFiles.",
+    );
+  });
+
+  it("rejects when no connected files are available", async () => {
+    vi.mocked(globalThis.fetch).mockResolvedValue(
+      new Response(JSON.stringify(["", "   "]), {
+        status: 200,
+        headers: { "Content-Type": "application/json" },
+      }),
+    );
+
+    await expect(discoverConnectedFileName("http://localhost:1365")).rejects.toThrow(
+      "fmBridge found no connected FileMaker files at http://localhost:1365/connectedFiles. Open FileMaker and load /webviewer?fileName=YourFile.",
+    );
+  });
+});
+
+describe("fmBridge", () => {
+  const originalFetch = globalThis.fetch;
+
+  beforeEach(() => {
+    globalThis.fetch = vi.fn();
+  });
+
+  afterEach(() => {
+    globalThis.fetch = originalFetch;
+  });
+
+  it("injects the bridge script in serve mode", async () => {
+    vi.mocked(globalThis.fetch).mockResolvedValue(
+      new Response(JSON.stringify(["Contacts"]), {
+        status: 200,
+        headers: { "Content-Type": "application/json" },
+      }),
+    );
+
+    const plugin = fmBridge({
+      fmHttpBaseUrl: "http://localhost:1365",
+      debug: true,
+    });
+
+    if (typeof plugin.apply === "function") {
+      expect(plugin.apply({} as never, { command: "serve", mode: "development" } as never)).toBe(true);
+    }
+
+    const tags = await plugin.transformIndexHtml?.("");
+
+    expect(tags).toEqual([
+      {
+        tag: "script",
+        attrs: {
+          src: "http://localhost:1365/fm-mock.js?fileName=Contacts&wsUrl=ws%3A%2F%2Flocalhost%3A1365%2Fws&debug=true",
+        },
+        injectTo: "head-prepend",
+      },
+    ]);
+    expect(globalThis.fetch).toHaveBeenCalledTimes(1);
+  });
+
+  it("opts out of build mode", async () => {
+    const plugin = fmBridge({
+      fmHttpBaseUrl: "http://localhost:1365",
+    });
+
+    expect(typeof plugin.apply).toBe("function");
+    if (typeof plugin.apply !== "function") {
+      return;
+    }
+
+    expect(plugin.apply({} as never, { command: "build", mode: "production" } as never)).toBe(false);
+    await expect(plugin.transformIndexHtml?.("")).resolves.toBeUndefined();
+    expect(globalThis.fetch).not.toHaveBeenCalled();
+  });
+});
diff --git a/packages/webviewer/vite.config.ts b/packages/webviewer/vite.config.ts
index 1e0f3b51..8c1c1070 100644
--- a/packages/webviewer/vite.config.ts
+++ b/packages/webviewer/vite.config.ts
@@ -8,7 +8,7 @@ const config = defineConfig({
 export default mergeConfig(
   config,
   tanstackViteConfig({
-    entry: ["./src/main.ts", "./src/adapter.ts"],
+    entry: ["./src/main.ts", "./src/adapter.ts", "./src/vite-plugins.ts"],
     externalDeps: ["@proofkit/fmdapi"],
     srcDir: "./src",
   }),
diff --git a/packages/webviewer/vitest.config.ts b/packages/webviewer/vitest.config.ts
new file mode 100644
index 00000000..3ca675a8
--- /dev/null
+++ b/packages/webviewer/vitest.config.ts
@@ -0,0 +1,7 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    exclude: ["**/node_modules/**", "**/dist/**"],
+  },
+});
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 44f9fb11..10b465f3 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -876,6 +876,9 @@ importers:
       vite:
         specifier: ^6.4.1
         version: 6.4.1(@types/node@22.19.5)(jiti@2.6.1)(lightningcss@1.30.2)(tsx@4.21.0)(yaml@2.8.2)
+      vitest:
+        specifier: ^4.0.17
+        version: 4.0.17(@types/node@22.19.5)(happy-dom@20.1.0)(jiti@2.6.1)(lightningcss@1.30.2)(msw@2.12.7(@types/node@22.19.5)(typescript@5.9.3))(tsx@4.21.0)(yaml@2.8.2)
 
 packages: