diff --git a/gitnexus/src/cli/wiki.ts b/gitnexus/src/cli/wiki.ts
index 8d9da9572..84aeb87bf 100644
--- a/gitnexus/src/cli/wiki.ts
+++ b/gitnexus/src/cli/wiki.ts
@@ -37,6 +37,15 @@ export interface WikiCommandOptions {
   retries?: string;
 }
 
+function parsePositiveIntegerOption(value: string | undefined, flag: string): number | undefined {
+  if (value === undefined) return undefined;
+  const trimmed = value.trim();
+  if (!/^[1-9]\d*$/.test(trimmed)) {
+    throw new Error(`${flag} must be a positive integer`);
+  }
+  return parseInt(trimmed, 10);
+}
+
 /**
  * Prompt the user for input via stdin.
  */
@@ -127,6 +136,15 @@ export const wikiCommand = async (inputPath?: string, options?: WikiCommandOptio
     return;
   }
 
+  let timeoutSeconds: number | undefined;
+  try {
+    timeoutSeconds = parsePositiveIntegerOption(options?.timeout, '--timeout');
+  } catch (error) {
+    console.log(`  Error: ${(error as Error).message}\n`);
+    process.exitCode = 1;
+    return;
+  }
+
   // ── Resolve LLM config (with interactive fallback) ─────────────────
   // Save any CLI overrides immediately
   if (
@@ -350,9 +368,8 @@ export const wikiCommand = async (inputPath?: string, options?: WikiCommandOptio
   }
 
   // ── Apply per-run overrides not saved to config ────────────────────
-  if (options?.timeout) {
-    const secs = parseInt(options.timeout, 10);
-    if (!isNaN(secs) && secs > 0) llmConfig.requestTimeoutMs = secs * 1000;
+  if (timeoutSeconds !== undefined) {
+    llmConfig.requestTimeoutMs = timeoutSeconds * 1000;
   }
   if (options?.retries) {
     const n = parseInt(options.retries, 10);
diff --git a/gitnexus/test/unit/wiki-flags.test.ts b/gitnexus/test/unit/wiki-flags.test.ts
index af19c676d..013251771 100644
--- a/gitnexus/test/unit/wiki-flags.test.ts
+++ b/gitnexus/test/unit/wiki-flags.test.ts
@@ -264,6 +264,88 @@ describe('WikiGenerator --review mode', () => {
   });
 });
 
+describe('wikiCommand --timeout validation', () => {
+  const originalExitCode = process.exitCode;
+
+  beforeEach(() => {
+    vi.resetModules();
+    process.exitCode = undefined;
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+    vi.doUnmock('../../src/storage/git.js');
+    vi.doUnmock('../../src/storage/repo-manager.js');
+    vi.doUnmock('../../src/core/wiki/llm-client.js');
+    vi.doUnmock('../../src/core/wiki/generator.js');
+    vi.doUnmock('cli-progress');
+    process.exitCode = originalExitCode;
+  });
+
+  it.each(['0', '-1', 'abc'])(
+    'rejects invalid --timeout value %s before starting generation',
+    async (timeout) => {
+      const generatorCtor = vi.fn().mockImplementation(() => ({
+        run: vi.fn(),
+      }));
+
+      vi.doMock('../../src/storage/git.js', () => ({
+        getGitRoot: vi.fn(),
+        isGitRepo: vi.fn().mockReturnValue(true),
+      }));
+      vi.doMock('../../src/storage/repo-manager.js', () => ({
+        getStoragePaths: vi
+          .fn()
+          .mockReturnValue({ storagePath: '/tmp/wiki-storage', lbugPath: '/tmp/wiki-db' }),
+        loadMeta: vi.fn().mockResolvedValue({ createdAt: '2026-01-01T00:00:00Z' }),
+        loadCLIConfig: vi.fn().mockResolvedValue({
+          apiKey: 'sk-test',
+          baseUrl: 'https://api.openai.com/v1',
+          model: 'gpt-4o',
+          provider: 'openai',
+        }),
+        saveCLIConfig: vi.fn(),
+      }));
+      vi.doMock('../../src/core/wiki/llm-client.js', async (importOriginal) => {
+        const actual = await importOriginal<typeof import('../../src/core/wiki/llm-client.js')>();
+        return {
+          ...actual,
+          resolveLLMConfig: vi.fn().mockResolvedValue({
+            apiKey: 'sk-test',
+            baseUrl: 'https://api.openai.com/v1',
+            model: 'gpt-4o',
+            maxTokens: 16_384,
+            temperature: 0,
+            provider: 'openai',
+          }),
+        };
+      });
+      vi.doMock('../../src/core/wiki/generator.js', () => ({
+        WikiGenerator: generatorCtor,
+      }));
+      vi.doMock('cli-progress', () => ({
+        default: {
+          SingleBar: vi.fn().mockImplementation(() => ({
+            start: vi.fn(),
+            update: vi.fn(),
+            stop: vi.fn(),
+          })),
+          Presets: { shades_grey: {} },
+        },
+      }));
+
+      const consoleSpy = vi.spyOn(console, 'log').mockImplementation(() => {});
+      const { wikiCommand } = await import('../../src/cli/wiki.js');
+
+      await wikiCommand('/tmp/repo', { timeout });
+
+      expect(process.exitCode).toBe(1);
+      expect(generatorCtor).not.toHaveBeenCalled();
+      expect(consoleSpy).toHaveBeenCalledWith('  Error: --timeout must be a positive integer\n');
+    },
+  );
+});
+
 // ─── CLI config round-trip with cursor provider ──────────────────────
 
 describe('CLI config round-trip with cursor provider', () => {