diff --git a/scripts/perf/issue-78851-model-resolution.ts b/scripts/perf/issue-78851-model-resolution.ts
index 6b504dd479bc..781122a551fe 100644
--- a/scripts/perf/issue-78851-model-resolution.ts
+++ b/scripts/perf/issue-78851-model-resolution.ts
@@ -26,6 +26,23 @@ type Options = {
   warmup: number;
 };
 
+const BOOLEAN_FLAGS = new Set(["--help", "-h", "--json", "--keep-temp", "--runtime-hooks"]);
+const VALUE_FLAGS = new Set([
+  "--agents",
+  "--cpu-prof-dir",
+  "--cpu-prof-output",
+  "--lookups",
+  "--models-per-provider",
+  "--output",
+  "--providers",
+  "--runs",
+  "--warmup",
+]);
+
+class CliArgumentError extends Error {
+  override name = "CliArgumentError";
+}
+
 type PhaseSample = {
   ensureMs: number;
   resolveMs: number;
@@ -73,7 +90,11 @@ function parseFlagValue(flag: string): string | undefined {
   if (index === -1) {
     return undefined;
   }
-  return process.argv[index + 1];
+  const value = process.argv[index + 1];
+  if (!value || value.startsWith("--")) {
+    throw new CliArgumentError(`${flag} requires a value`);
+  }
+  return value;
 }
 
 function hasFlag(flag: string): boolean {
@@ -85,9 +106,12 @@ function parsePositiveInt(flag: string, fallback: number): number {
   if (!raw) {
     return fallback;
   }
-  const value = Number.parseInt(raw, 10);
+  const value = Number(raw);
   if (!Number.isFinite(value) || value <= 0) {
-    throw new Error(`${flag} must be a positive integer`);
+    throw new CliArgumentError(`${flag} must be a positive integer`);
+  }
+  if (!Number.isInteger(value)) {
+    throw new CliArgumentError(`${flag} must be a positive integer`);
   }
   return value;
 }
@@ -97,14 +121,32 @@ function parseNonNegativeInt(flag: string, fallback: number): number {
   if (!raw) {
     return fallback;
   }
-  const value = Number.parseInt(raw, 10);
+  const value = Number(raw);
   if (!Number.isFinite(value) || value < 0) {
-    throw new Error(`${flag} must be a non-negative integer`);
+    throw new CliArgumentError(`${flag} must be a non-negative integer`);
+  }
+  if (!Number.isInteger(value)) {
+    throw new CliArgumentError(`${flag} must be a non-negative integer`);
   }
   return value;
 }
 
+function validateCliArgs(args = process.argv.slice(2)): void {
+  for (let index = 0; index < args.length; index += 1) {
+    const arg = args[index] ?? "";
+    if (BOOLEAN_FLAGS.has(arg)) {
+      continue;
+    }
+    if (VALUE_FLAGS.has(arg)) {
+      index += 1;
+      continue;
+    }
+    throw new CliArgumentError(`Unknown argument: ${arg}`);
+  }
+}
+
 function parseOptions(): Options {
+  validateCliArgs();
   return {
     agentCount: parsePositiveInt("--agents", 8),
     cpuProfDir: parseFlagValue("--cpu-prof-dir"),
@@ -494,6 +536,10 @@ async function main(): Promise<void> {
 }
 
 main().catch((error: unknown) => {
+  if (error instanceof CliArgumentError) {
+    process.stderr.write(`${error.message}\n`);
+    process.exit(1);
+  }
   const message = error instanceof Error ? (error.stack ?? error.message) : String(error);
   process.stderr.write(`${message}\n`);
   process.exit(1);
diff --git a/test/scripts/issue-78851-model-resolution.test.ts b/test/scripts/issue-78851-model-resolution.test.ts
new file mode 100644
index 000000000000..18a5118af5de
--- /dev/null
+++ b/test/scripts/issue-78851-model-resolution.test.ts
@@ -0,0 +1,43 @@
+// Issue 78851 profiler CLI tests cover argument handling before work starts.
+import { spawnSync } from "node:child_process";
+import { describe, expect, it } from "vitest";
+
+function runProfiler(...args: string[]) {
+  return spawnSync(
+    process.execPath,
+    ["--import", "tsx", "scripts/perf/issue-78851-model-resolution.ts", ...args],
+    {
+      cwd: process.cwd(),
+      encoding: "utf8",
+    },
+  );
+}
+
+describe("issue 78851 model resolution profiler CLI", () => {
+  it("prints help without starting the profiler", () => {
+    const result = runProfiler("--help");
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain("OpenClaw issue #78851 model-resolution profiler");
+    expect(result.stdout).toContain(
+      "node --import tsx scripts/perf/issue-78851-model-resolution.ts [options]",
+    );
+    expect(result.stderr).toBe("");
+  });
+
+  it("rejects unknown arguments before starting the profiler", () => {
+    const result = runProfiler("--wat");
+
+    expect(result.status).toBe(1);
+    expect(result.stdout).toBe("");
+    expect(result.stderr.trim()).toBe("Unknown argument: --wat");
+  });
+
+  it("rejects partial numeric arguments before starting the profiler", () => {
+    const result = runProfiler("--providers", "48junk");
+
+    expect(result.status).toBe(1);
+    expect(result.stdout).toBe("");
+    expect(result.stderr.trim()).toBe("--providers must be a positive integer");
+  });
+});