diff --git a/samples/eve-browser-network/browser/main.ts b/samples/eve-browser-network/browser/main.ts
index fac4cc43..fc57e364 100644
--- a/samples/eve-browser-network/browser/main.ts
+++ b/samples/eve-browser-network/browser/main.ts
@@ -6,10 +6,29 @@ import {
   decodeCultNetOperationPayload,
   decodeCultNetPayload,
 } from "cultmesh-browser";
+import { defineDocumentType } from "@gamecult/cultcache-ts/document";
+
+// A payload is read through the definition that says how its bytes are laid out. These are plain-map definitions: the
+// provider's CultCache types are integer-keyed MessagePack, and the Eve documents are validated by their own parsers.
+// CounterState is [counterId, count, receipts].
+const counterDocument = defineDocumentType({
+  type: "sample.counter_state",
+  schemaId: "sample.counter_state.v1",
+  schema: {
+    parse: (value: unknown): [string, number, unknown] => {
+      if (!Array.isArray(value) || typeof value[0] !== "string" || typeof value[1] !== "number") {
+        throw new Error("The counter state document is not [counterId, count, receipts].");
+      }
+      return [value[0], value[1], value[2]];
+    },
+  },
+});
+const eveDocument = (type: string) => defineDocumentType({ type, schemaId: `${type}.v1`, schema: { parse: (value: unknown) => value } });
+const surfaceDocument = eveDocument("gamecult.eve.surface");
+const advertisementDocument = eveDocument("gamecult.eve.provider_advertisement");
 
-// CounterState is an integer-keyed MessagePack object: [counterId, count, receipts].
 const counterCount = (record: Parameters<typeof decodeCultNetPayload>[0]) =>
-  decodeCultNetPayload<[string, number, unknown]>(record)[1];
+  decodeCultNetPayload(record, counterDocument)[1];
 
 declare global {
   interface Window {
@@ -63,8 +82,12 @@ try {
     recordKey: "sample.counter-ui",
     subscriptionId: "browser-provider",
   });
-  const provider = parseEveProviderAdvertisement(decodeCultNetPayload(advertisement.current!));
-  const currentSurface = parseEveSurfaceDocument(decodeCultNetPayload(surface.current!));
+  // Eve's generated contract type and the lowering's own interface disagree on optional plugin requirements; the
+  // value is the one parseEveProviderAdvertisement validated.
+  const provider = parseEveProviderAdvertisement(
+    decodeCultNetPayload(advertisement.current!, advertisementDocument),
+  ) as unknown as NonNullable<Parameters<typeof renderEveSurface>[2]>["provider"];
+  const currentSurface = parseEveSurfaceDocument(decodeCultNetPayload(surface.current!, surfaceDocument));
   renderEveSurface(currentSurface, host, {
     activeSurfaceId: "sample.counter",
     clientId: "sample.chromium",
@@ -77,10 +100,8 @@ try {
         payload: { amount: 1 },
         idempotencyKey: window.__sampleCommandId,
       });
-      const receipt = parseEveCommandReceipt(decodeCultNetOperationPayload(response)) as {
-        receiptId: string;
-        count: number;
-      };
+      const receipt = decodeCultNetOperationPayload<{ receiptId: string; count: number }>(response);
+      parseEveCommandReceipt(receipt);
       window.__sampleReceipt = receipt;
       receiptOutput.textContent = receipt.receiptId;
     },
diff --git a/scripts/verify-eve-browser-network.mjs b/scripts/verify-eve-browser-network.mjs
index c1388712..dfa8d931 100644
--- a/scripts/verify-eve-browser-network.mjs
+++ b/scripts/verify-eve-browser-network.mjs
@@ -2,7 +2,7 @@ import assert from "node:assert/strict";
 import { spawn } from "node:child_process";
 import { existsSync } from "node:fs";
 import { createServer as createHttpServer } from "node:http";
-import { mkdtemp, readFile, rm } from "node:fs/promises";
+import { mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
 import { createServer as createNetServer } from "node:net";
 import { tmpdir } from "node:os";
 import { dirname, join, resolve } from "node:path";
@@ -38,8 +38,33 @@ let browser;
 
 try {
   const tsc = join(repoRoot, "node_modules", "typescript", "bin", "tsc");
+  await run(process.execPath, [tsc, "-p", join(repoRoot, "packages", "cultcache-ts", "tsconfig.json"), "--pretty", "false"]);
   await run(process.execPath, [tsc, "-p", join(repoRoot, "packages", "cultnet-ts", "tsconfig.json"), "--pretty", "false"]);
   await run(process.execPath, [tsc, "-p", join(repoRoot, "packages", "cultmesh-browser", "tsconfig.json"), "--pretty", "false"]);
+  // esbuild strips types, so a package signature change would otherwise surface as a browser error. The page is
+  // type-checked against the same module map the bundle uses.
+  const moduleMap = {
+    "@gamecult/eve-contracts": join(eveRoot, "packages", "eve-contracts", "src", "index.ts"),
+    "@gamecult/eve-browser-lowering": join(eveRoot, "packages", "eve-browser-lowering", "src", "index.ts"),
+    "cultmesh-browser": join(repoRoot, "packages", "cultmesh-browser", "src", "index.ts"),
+    "cultnet-ts/contracts": join(repoRoot, "packages", "cultnet-ts", "src", "contracts.ts"),
+  };
+  const sampleTsconfig = join(workRoot, "tsconfig.json");
+  await writeFile(sampleTsconfig, JSON.stringify({
+    compilerOptions: {
+      target: "ES2022",
+      module: "ES2022",
+      moduleResolution: "Bundler",
+      lib: ["ES2022", "ESNext.Disposable", "DOM", "DOM.Iterable"],
+      strict: true,
+      noEmit: true,
+      skipLibCheck: true,
+      types: [],
+      paths: Object.fromEntries(Object.entries(moduleMap).map(([name, target]) => [name, [target]])),
+    },
+    files: [join(sampleRoot, "browser", "main.ts")],
+  }));
+  await run(process.execPath, [tsc, "-p", sampleTsconfig, "--pretty", "false"]);
   await build({
     entryPoints: [join(sampleRoot, "browser", "main.ts")],
     outfile: bundlePath,
@@ -48,12 +73,7 @@ try {
     platform: "browser",
     target: "es2022",
     sourcemap: true,
-    alias: {
-      "@gamecult/eve-contracts": join(eveRoot, "packages", "eve-contracts", "src", "index.ts"),
-      "@gamecult/eve-browser-lowering": join(eveRoot, "packages", "eve-browser-lowering", "src", "index.ts"),
-      "cultmesh-browser": join(repoRoot, "packages", "cultmesh-browser", "src", "index.ts"),
-      "cultnet-ts/contracts": join(repoRoot, "packages", "cultnet-ts", "src", "contracts.ts"),
-    },
+    alias: moduleMap,
     logLevel: "warning",
   });
   const bundle = await readFile(bundlePath, "utf8");