diff --git a/src/browser/cdp.ts b/src/browser/cdp.ts
index 2b34d366..d8669c33 100644
--- a/src/browser/cdp.ts
+++ b/src/browser/cdp.ts
@@ -179,13 +179,17 @@ export class CDPBridge {
 }
 
 class CDPPage implements IPage {
+  private _pageEnabled = false;
   constructor(private bridge: CDPBridge) {}
 
   /** Navigate with proper load event waiting (P1 fix #3) */
   async goto(url: string, options?: { waitUntil?: 'load' | 'none'; settleMs?: number }): Promise<void> {
-    await this.bridge.send('Page.enable');
+    if (!this._pageEnabled) {
+      await this.bridge.send('Page.enable');
+      this._pageEnabled = true;
+    }
     const loadPromise = this.bridge.waitForEvent('Page.loadEventFired', 30_000)
-      .catch(() => {}); // Don't fail if event times out
+      .catch(() => {}); // Don't fail if load event times out — page may be an SPA
     await this.bridge.send('Page.navigate', { url });
     await loadPromise;
     // Smart settle: use DOM stability detection instead of fixed sleep.
diff --git a/src/browser/mcp.ts b/src/browser/mcp.ts
index c5e80634..4349b644 100644
--- a/src/browser/mcp.ts
+++ b/src/browser/mcp.ts
@@ -9,6 +9,7 @@ import * as fs from 'node:fs';
 import type { IPage } from '../types.js';
 import { Page } from './page.js';
 import { isDaemonRunning, isExtensionConnected } from './daemon-client.js';
+import { DEFAULT_DAEMON_PORT } from '../constants.js';
 
 const DAEMON_SPAWN_TIMEOUT = 10000; // 10s to wait for daemon + extension
 
@@ -112,7 +113,7 @@ export class BrowserBridge {
     throw new Error(
       'Failed to start opencli daemon. Try running manually:\n' +
       `  node ${daemonPath}\n` +
-      'Make sure port 19825 is available.',
+      `Make sure port ${DEFAULT_DAEMON_PORT} is available.`,
     );
   }
 }
diff --git a/src/browser/page.ts b/src/browser/page.ts
index 0251b226..5576fe01 100644
--- a/src/browser/page.ts
+++ b/src/browser/page.ts
@@ -184,7 +184,7 @@ export class Page implements IPage {
       await new Promise(resolve => setTimeout(resolve, options * 1000));
       return;
     }
-    if (options.time) {
+    if (typeof options.time === 'number') {
       await new Promise(resolve => setTimeout(resolve, options.time! * 1000));
       return;
     }
diff --git a/src/build-manifest.ts b/src/build-manifest.ts
index 633ea905..bf853f6e 100644
--- a/src/build-manifest.ts
+++ b/src/build-manifest.ts
@@ -179,7 +179,8 @@ export function parseTsArgsBlock(argsBlock: string): ManifestEntry['args'] {
       choices: parseInlineChoices(body),
     });
 
-    cursor = objectStart + body.length + 2;
+    cursor = objectStart + body.length;
+    if (cursor <= objectStart) break; // safety: prevent infinite loop
   }
 
   return args;
@@ -300,7 +301,7 @@ export function scanTs(filePath: string, site: string): ManifestEntry | null {
  * prefer the TS version (it self-registers and typically has richer logic).
  */
 export function shouldReplaceManifestEntry(current: ManifestEntry, next: ManifestEntry): boolean {
-  if (current.type === next.type) return true;
+  if (current.type === next.type) return false;
   return current.type === 'yaml' && next.type === 'ts';
 }
 
diff --git a/src/cascade.ts b/src/cascade.ts
index fc4c8120..3e8662aa 100644
--- a/src/cascade.ts
+++ b/src/cascade.ts
@@ -145,9 +145,10 @@ export async function cascadeProbe(
   url: string,
   opts: { maxStrategy?: Strategy; timeout?: number } = {},
 ): Promise<CascadeResult> {
-  const maxIdx = opts.maxStrategy
+  const rawIdx = opts.maxStrategy
     ? CASCADE_ORDER.indexOf(opts.maxStrategy)
     : CASCADE_ORDER.indexOf(Strategy.HEADER); // Don't auto-try INTERCEPT/UI
+  const maxIdx = rawIdx === -1 ? CASCADE_ORDER.indexOf(Strategy.HEADER) : rawIdx;
 
   const probes: ProbeResult[] = [];
 
diff --git a/src/download/index.ts b/src/download/index.ts
index 21e4d166..d8e2963d 100644
--- a/src/download/index.ts
+++ b/src/download/index.ts
@@ -199,7 +199,9 @@ export function exportCookiesToNetscape(
     const cookiePath = cookie.path || '/';
     const secure = cookie.secure ? 'TRUE' : 'FALSE';
     const expiry = Math.floor(Date.now() / 1000) + 86400 * 365; // 1 year from now
-    lines.push(`${domain}\t${includeSubdomains}\t${cookiePath}\t${secure}\t${expiry}\t${cookie.name}\t${cookie.value}`);
+    const safeName = cookie.name.replace(/[\t\n\r]/g, '');
+    const safeValue = cookie.value.replace(/[\t\n\r]/g, '');
+    lines.push(`${domain}\t${includeSubdomains}\t${cookiePath}\t${secure}\t${expiry}\t${safeName}\t${safeValue}`);
   }
 
   fs.mkdirSync(path.dirname(filePath), { recursive: true });
@@ -237,8 +239,13 @@ export async function ytdlpDownload(
       '--progress',
     ];
 
-    if (cookiesFile && fs.existsSync(cookiesFile)) {
-      args.push('--cookies', cookiesFile);
+    if (cookiesFile) {
+      if (fs.existsSync(cookiesFile)) {
+        args.push('--cookies', cookiesFile);
+      } else {
+        console.error(`[download] Cookies file not found: ${cookiesFile}, falling back to browser cookies`);
+        args.push('--cookies-from-browser', 'chrome');
+      }
     } else {
       // Try to use browser cookies
       args.push('--cookies-from-browser', 'chrome');
diff --git a/src/execution.ts b/src/execution.ts
index 4aa5a04b..b9841851 100644
--- a/src/execution.ts
+++ b/src/execution.ts
@@ -157,7 +157,9 @@ export async function executeCommand(
       // Each adapter controls this via `navigateBefore` (see CliCommand docs).
       const preNavUrl = resolvePreNav(cmd);
       if (preNavUrl) {
-        try { await page.goto(preNavUrl); await page.wait(2); } catch {}
+        try { await page.goto(preNavUrl); await page.wait(2); } catch (err) {
+          if (debug) console.error(`[pre-nav] Failed to navigate to ${preNavUrl}: ${err instanceof Error ? err.message : err}`);
+        }
       }
       return runWithTimeout(runCommand(cmd, page, kwargs, debug), {
         timeout: cmd.timeoutSeconds ?? DEFAULT_BROWSER_COMMAND_TIMEOUT,
diff --git a/src/plugin.ts b/src/plugin.ts
index e200dbfc..2dd2399c 100644
--- a/src/plugin.ts
+++ b/src/plugin.ts
@@ -32,8 +32,8 @@ function postInstallLifecycle(pluginDir: string): void {
       encoding: 'utf-8',
       stdio: ['pipe', 'pipe', 'pipe'],
     });
-  } catch {
-    // Non-fatal: npm install may fail if no real deps
+  } catch (err) {
+    console.error(`[plugin] npm install failed in ${pluginDir}: ${err instanceof Error ? err.message : err}`);
   }
 
   // Symlink host opencli so TS plugins resolve '@jackwener/opencli/registry'
diff --git a/src/runtime.ts b/src/runtime.ts
index f2ebd343..a88a5f08 100644
--- a/src/runtime.ts
+++ b/src/runtime.ts
@@ -10,10 +10,21 @@ export function getBrowserFactory(): new () => IBrowserFactory {
   return (process.env.OPENCLI_CDP_ENDPOINT ? CDPBridge : BrowserBridge) as unknown as new () => IBrowserFactory;
 }
 
-export const DEFAULT_BROWSER_CONNECT_TIMEOUT = parseInt(process.env.OPENCLI_BROWSER_CONNECT_TIMEOUT ?? '30', 10);
-export const DEFAULT_BROWSER_COMMAND_TIMEOUT = parseInt(process.env.OPENCLI_BROWSER_COMMAND_TIMEOUT ?? '60', 10);
-export const DEFAULT_BROWSER_EXPLORE_TIMEOUT = parseInt(process.env.OPENCLI_BROWSER_EXPLORE_TIMEOUT ?? '120', 10);
-export const DEFAULT_BROWSER_SMOKE_TIMEOUT = parseInt(process.env.OPENCLI_BROWSER_SMOKE_TIMEOUT ?? '60', 10);
+function parseEnvTimeout(envVar: string, fallback: number): number {
+  const raw = process.env[envVar];
+  if (raw === undefined) return fallback;
+  const parsed = parseInt(raw, 10);
+  if (Number.isNaN(parsed) || parsed <= 0) {
+    console.error(`[runtime] Invalid ${envVar}="${raw}", using default ${fallback}s`);
+    return fallback;
+  }
+  return parsed;
+}
+
+export const DEFAULT_BROWSER_CONNECT_TIMEOUT = parseEnvTimeout('OPENCLI_BROWSER_CONNECT_TIMEOUT', 30);
+export const DEFAULT_BROWSER_COMMAND_TIMEOUT = parseEnvTimeout('OPENCLI_BROWSER_COMMAND_TIMEOUT', 60);
+export const DEFAULT_BROWSER_EXPLORE_TIMEOUT = parseEnvTimeout('OPENCLI_BROWSER_EXPLORE_TIMEOUT', 120);
+export const DEFAULT_BROWSER_SMOKE_TIMEOUT = parseEnvTimeout('OPENCLI_BROWSER_SMOKE_TIMEOUT', 60);
 
 /**
  * Timeout with seconds unit. Used for high-level command timeouts.