diff --git a/src/docker-manager.test.ts b/src/docker-manager.test.ts
index e3d74ec7..257b3706 100644
--- a/src/docker-manager.test.ts
+++ b/src/docker-manager.test.ts
@@ -1645,6 +1645,42 @@ describe('docker-manager', () => {
       }
     });
 
+    it('should skip env vars exceeding MAX_ENV_VALUE_SIZE from env-all passthrough', () => {
+      const largeVarName = 'AWF_TEST_OVERSIZED_VAR';
+      const saved = process.env[largeVarName];
+      // Create a value larger than 64KB
+      process.env[largeVarName] = 'x'.repeat(65 * 1024);
+
+      try {
+        const configWithEnvAll = { ...mockConfig, envAll: true };
+        const result = generateDockerCompose(configWithEnvAll, mockNetworkConfig);
+        const env = result.services.agent.environment as Record<string, string>;
+
+        // Oversized var should be skipped
+        expect(env[largeVarName]).toBeUndefined();
+      } finally {
+        if (saved !== undefined) process.env[largeVarName] = saved;
+        else delete process.env[largeVarName];
+      }
+    });
+
+    it('should pass env vars under MAX_ENV_VALUE_SIZE from env-all passthrough', () => {
+      const normalVarName = 'AWF_TEST_NORMAL_VAR';
+      const saved = process.env[normalVarName];
+      process.env[normalVarName] = 'normal_value';
+
+      try {
+        const configWithEnvAll = { ...mockConfig, envAll: true };
+        const result = generateDockerCompose(configWithEnvAll, mockNetworkConfig);
+        const env = result.services.agent.environment as Record<string, string>;
+
+        expect(env[normalVarName]).toBe('normal_value');
+      } finally {
+        if (saved !== undefined) process.env[normalVarName] = saved;
+        else delete process.env[normalVarName];
+      }
+    });
+
     it('should auto-inject GH_HOST from GITHUB_SERVER_URL when envAll is true', () => {
       const prevServerUrl = process.env.GITHUB_SERVER_URL;
       const prevGhHost = process.env.GH_HOST;
diff --git a/src/docker-manager.ts b/src/docker-manager.ts
index 802abd61..b6582e71 100644
--- a/src/docker-manager.ts
+++ b/src/docker-manager.ts
@@ -24,6 +24,19 @@ const API_PROXY_CONTAINER_NAME = 'awf-api-proxy';
 const DOH_PROXY_CONTAINER_NAME = 'awf-doh-proxy';
 const CLI_PROXY_CONTAINER_NAME = 'awf-cli-proxy';
 
+/**
+ * Maximum size (bytes) of a single environment variable value allowed through
+ * --env-all passthrough. Variables exceeding this are skipped with a warning
+ * to prevent E2BIG errors from ARG_MAX exhaustion.
+ */
+const MAX_ENV_VALUE_SIZE = 64 * 1024; // 64 KB
+
+/**
+ * Total environment size (bytes) threshold for issuing an ARG_MAX warning.
+ * Linux ARG_MAX is ~2 MB for argv + envp combined; warn well before that.
+ */
+const ENV_SIZE_WARNING_THRESHOLD = 1_500_000; // ~1.5 MB
+
 /**
  * Flag set by fastKillAgentContainer() to signal runAgentCommand() that
  * the container was externally stopped. When true, runAgentCommand() skips
@@ -794,11 +807,27 @@ export function generateDockerCompose(
 
   // If --env-all is specified, pass through all host environment variables (except excluded ones)
   if (config.envAll) {
+    const skippedLargeVars: string[] = [];
     for (const [key, value] of Object.entries(process.env)) {
       if (value !== undefined && !EXCLUDED_ENV_VARS.has(key) && !Object.prototype.hasOwnProperty.call(environment, key)) {
+        // Skip oversized values to prevent E2BIG (Argument list too long) errors.
+        // The Linux kernel enforces ARG_MAX (~2MB) on argv+envp combined; large env
+        // vars can exhaust this budget, especially when combined with large prompts.
+        const valueSizeBytes = Buffer.byteLength(value, 'utf8');
+        if (valueSizeBytes > MAX_ENV_VALUE_SIZE) {
+          skippedLargeVars.push(`${key} (${(valueSizeBytes / 1024).toFixed(0)} KB)`);
+          continue;
+        }
         environment[key] = value;
       }
     }
+    if (skippedLargeVars.length > 0) {
+      logger.warn(`Skipped ${skippedLargeVars.length} oversized env var(s) from --env-all passthrough (>${(MAX_ENV_VALUE_SIZE / 1024).toFixed(0)} KB each):`);
+      for (const entry of skippedLargeVars) {
+        logger.warn(`  - ${entry}`);
+      }
+      logger.warn('Use --env VAR="$VAR" to explicitly pass large values if needed.');
+    }
   } else {
     // Default behavior: selectively pass through specific variables
     if (process.env.GITHUB_TOKEN) environment.GITHUB_TOKEN = process.env.GITHUB_TOKEN;
@@ -903,6 +932,21 @@ export function generateDockerCompose(
     }
   }
 
+  // Warn when total environment size approaches ARG_MAX (~2MB).
+  // Linux enforces a combined argv+envp limit; large environments can cause E2BIG errors
+  // when execve() is called inside the container.
+  if (config.envAll) {
+    const totalEnvBytes = Object.entries(environment)
+      .reduce((sum, [k, v]) => sum + k.length + (v?.length ?? 0) + 2, 0); // +2 for '=' and null
+    if (totalEnvBytes > ENV_SIZE_WARNING_THRESHOLD) {
+      logger.warn(
+        `⚠️  Total container environment size is ${(totalEnvBytes / 1024).toFixed(0)} KB — ` +
+        'may cause E2BIG (Argument list too long) errors when combined with large command arguments'
+      );
+      logger.warn('   Consider using --exclude-env to remove unnecessary variables');
+    }
+  }
+
   // DNS servers for Docker embedded DNS forwarding (used in docker-compose dns: field)
   const dnsServers = config.dnsServers || DEFAULT_DNS_SERVERS;
   // Pass DNS servers to container so setup-iptables.sh can allow Docker DNS forwarding