diff --git a/config.example.toml b/config.example.toml
index de0222e7..038690cc 100644
--- a/config.example.toml
+++ b/config.example.toml
@@ -90,6 +90,34 @@ allow_shell = true
 approval_policy = "on-request" # on-request | untrusted | never
 sandbox_mode = "workspace-write" # read-only | workspace-write | danger-full-access | external-sandbox
 
+# ─────────────────────────────────────────────────────────────────────────────────
+# External Sandbox Backend (pluggable remote execution)
+# ─────────────────────────────────────────────────────────────────────────────────
+# When sandbox_backend is set to "opensandbox", all exec_shell calls are
+# routed through an external OpenSandbox-compatible HTTP API instead of
+# spawning a local process. The backend sends `POST {sandbox_url}/v1/sandbox/run`
+# with `{"cmd": "...", "env": {...}}` and expects
+# `{"stdout": "...", "stderr": "...", "exit_code": 0}`.
+#
+# sandbox_backend = "none"          # "none" (default) or "opensandbox"
+# sandbox_url = "http://localhost:8080"  # OpenSandbox-compatible API base URL
+# sandbox_api_key = "YOUR_API_KEY"  # Optional Bearer token sent with requests
+#
+# Env-var overrides:
+#   DEEPSEEK_SANDBOX_BACKEND   → sandbox_backend
+#   DEEPSEEK_SANDBOX_URL       → sandbox_url
+#   DEEPSEEK_SANDBOX_API_KEY   → sandbox_api_key
+#
+# Example OpenSandbox setup:
+#
+#   sandbox_backend = "opensandbox"
+#   sandbox_url = "http://localhost:8080"
+#   sandbox_api_key = "sk-opensandbox-secret"
+#
+# The backend uses a 30-second HTTP timeout. Background, interactive, and
+# TTY modes are not supported with external backends — all commands run
+# synchronously via HTTP.
+
 # auto_allow entries match by command prefix, not raw string.
 # See command_safety.rs for the prefix dictionary.
 #
diff --git a/crates/tui/src/config.rs b/crates/tui/src/config.rs
index 6072c177..d7831c5f 100644
--- a/crates/tui/src/config.rs
+++ b/crates/tui/src/config.rs
@@ -726,6 +726,14 @@ pub struct Config {
     pub allow_shell: Option<bool>,
     pub approval_policy: Option<String>,
     pub sandbox_mode: Option<String>,
+    /// External sandbox backend: `"none"` or `"opensandbox"`.
+    /// When set, exec_shell routes commands through the backend's HTTP API
+    /// instead of spawning a local process.
+    pub sandbox_backend: Option<String>,
+    /// Base URL for the external sandbox backend (default: `"http://localhost:8080"`).
+    pub sandbox_url: Option<String>,
+    /// Optional API key for the external sandbox backend (sent as Bearer token).
+    pub sandbox_api_key: Option<String>,
     pub managed_config_path: Option<String>,
     pub requirements_path: Option<String>,
     pub max_subagents: Option<usize>,
@@ -1742,6 +1750,15 @@ fn apply_env_overrides(config: &mut Config) {
     if let Ok(value) = std::env::var("DEEPSEEK_SANDBOX_MODE") {
         config.sandbox_mode = Some(value);
     }
+    if let Ok(value) = std::env::var("DEEPSEEK_SANDBOX_BACKEND") {
+        config.sandbox_backend = Some(value);
+    }
+    if let Ok(value) = std::env::var("DEEPSEEK_SANDBOX_URL") {
+        config.sandbox_url = Some(value);
+    }
+    if let Ok(value) = std::env::var("DEEPSEEK_SANDBOX_API_KEY") {
+        config.sandbox_api_key = Some(value);
+    }
     if let Ok(value) = std::env::var("DEEPSEEK_MANAGED_CONFIG_PATH") {
         config.managed_config_path = Some(value);
     }
@@ -1999,6 +2016,9 @@ fn merge_config(base: Config, override_cfg: Config) -> Config {
         allow_shell: override_cfg.allow_shell.or(base.allow_shell),
         approval_policy: override_cfg.approval_policy.or(base.approval_policy),
         sandbox_mode: override_cfg.sandbox_mode.or(base.sandbox_mode),
+        sandbox_backend: override_cfg.sandbox_backend.or(base.sandbox_backend),
+        sandbox_url: override_cfg.sandbox_url.or(base.sandbox_url),
+        sandbox_api_key: override_cfg.sandbox_api_key.or(base.sandbox_api_key),
         managed_config_path: override_cfg
             .managed_config_path
             .or(base.managed_config_path),
diff --git a/crates/tui/src/sandbox/backend.rs b/crates/tui/src/sandbox/backend.rs
new file mode 100644
index 00000000..c3eb9afc
--- /dev/null
+++ b/crates/tui/src/sandbox/backend.rs
@@ -0,0 +1,95 @@
+//! Pluggable sandbox backend abstraction.
+//!
+//! External sandbox backends route shell command execution to a remote service
+//! (e.g. Alibaba OpenSandbox) instead of spawning a local process. This is
+//! complementary to the OS-level sandbox module (Seatbelt / Landlock / Windows)
+//! — the external backend *replaces* local execution entirely when configured.
+
+use std::collections::HashMap;
+
+use anyhow::Result;
+use async_trait::async_trait;
+
+/// Output from a sandbox backend execution.
+#[derive(Debug, Clone)]
+pub struct SandboxOutput {
+    /// Standard output from the command.
+    pub stdout: String,
+    /// Standard error from the command.
+    pub stderr: String,
+    /// Exit code (0 for success).
+    pub exit_code: i32,
+}
+
+/// The kind of external sandbox backend.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum SandboxKind {
+    /// No external sandbox — execute commands locally.
+    None,
+    /// Alibaba OpenSandbox remote execution.
+    OpenSandbox,
+}
+
+impl SandboxKind {
+    /// Parse a sandbox backend name from config (case-insensitive).
+    #[must_use]
+    pub fn parse(value: &str) -> Option<Self> {
+        match value.trim().to_ascii_lowercase().as_str() {
+            "none" | "" => Some(Self::None),
+            "opensandbox" | "open-sandbox" | "open_sandbox" => Some(Self::OpenSandbox),
+            _ => None,
+        }
+    }
+
+    /// Human-readable label.
+    #[must_use]
+    pub fn as_str(self) -> &'static str {
+        match self {
+            Self::None => "none",
+            Self::OpenSandbox => "opensandbox",
+        }
+    }
+}
+
+/// Abstract interface for an external sandbox backend.
+///
+/// Implementations send commands to a remote execution environment and return
+/// structured output. The trait is `Send + Sync` so it can be stored in an
+/// `Arc` and shared across async tasks.
+#[async_trait]
+pub trait SandboxBackend: Send + Sync {
+    /// Execute a shell command and return its output.
+    ///
+    /// `cmd` is the full shell command string (e.g. `"ls -la"`).
+    /// `env` contains additional environment variables to set.
+    async fn exec(&self, cmd: &str, env: &HashMap<String, String>) -> Result<SandboxOutput>;
+}
+
+use crate::config::Config;
+
+/// Create the configured sandbox backend from config.
+///
+/// Returns `None` when no external sandbox backend is configured (i.e. the
+/// `sandbox_backend` key is absent, empty, or `"none"`). When `"opensandbox"`
+/// is set, constructs an [`OpenSandboxBackend`] using `sandbox_url` and
+/// `sandbox_api_key`.
+pub fn create_backend(config: &Config) -> Result<Option<Box<dyn SandboxBackend>>> {
+    let kind = config
+        .sandbox_backend
+        .as_deref()
+        .and_then(SandboxKind::parse)
+        .unwrap_or(SandboxKind::None);
+
+    match kind {
+        SandboxKind::None => Ok(None),
+        SandboxKind::OpenSandbox => {
+            let base_url = config
+                .sandbox_url
+                .clone()
+                .unwrap_or_else(|| "http://localhost:8080".to_string());
+            let api_key = config.sandbox_api_key.clone();
+            let backend = super::opensandbox::OpenSandboxBackend::new(base_url, api_key, 30);
+            Ok(Some(Box::new(backend)))
+        }
+    }
+}
diff --git a/crates/tui/src/sandbox/mod.rs b/crates/tui/src/sandbox/mod.rs
index b6678783..3d9a9314 100644
--- a/crates/tui/src/sandbox/mod.rs
+++ b/crates/tui/src/sandbox/mod.rs
@@ -25,6 +25,8 @@
 //! // exec_env.command now contains the sandboxed command
 //! ```
 
+pub mod backend;
+pub mod opensandbox;
 pub mod policy;
 
 #[cfg(target_os = "macos")]
diff --git a/crates/tui/src/sandbox/opensandbox.rs b/crates/tui/src/sandbox/opensandbox.rs
new file mode 100644
index 00000000..884c9e50
--- /dev/null
+++ b/crates/tui/src/sandbox/opensandbox.rs
@@ -0,0 +1,124 @@
+//! Alibaba OpenSandbox backend adapter.
+//!
+//! Sends shell commands to an OpenSandbox-compatible HTTP API for remote
+//! execution.  The API endpoint is `POST {base_url}/v1/sandbox/run` with
+//! JSON body `{"cmd": "...", "env": {...}}` and expects a JSON response
+//! `{"stdout": "...", "stderr": "...", "exit_code": 0}`.
+
+use std::collections::HashMap;
+use std::time::Duration;
+
+use anyhow::{Context, Result};
+use async_trait::async_trait;
+use serde::Deserialize;
+use serde::Serialize;
+
+use super::backend::{SandboxBackend, SandboxOutput};
+
+/// Request body sent to the OpenSandbox `/v1/sandbox/run` endpoint.
+#[derive(Debug, Serialize)]
+struct SandboxRunRequest {
+    /// Full shell command to execute.
+    cmd: String,
+    /// Environment variables to set in the sandbox.
+    env: HashMap<String, String>,
+}
+
+/// Response body from the OpenSandbox `/v1/sandbox/run` endpoint.
+#[derive(Debug, Deserialize)]
+struct SandboxRunResponse {
+    /// Standard output from the command.
+    stdout: String,
+    /// Standard error from the command.
+    stderr: String,
+    /// Exit code (0 for success).
+    exit_code: i32,
+}
+
+/// An OpenSandbox-compatible remote execution backend.
+///
+/// Constructed with a base URL (e.g. `"http://localhost:8080"`), an optional
+/// API key sent as a `Bearer` token, and a timeout in seconds.
+pub struct OpenSandboxBackend {
+    base_url: String,
+    api_key: Option<String>,
+    timeout_secs: u64,
+    client: reqwest::Client,
+}
+
+impl OpenSandboxBackend {
+    /// Create a new OpenSandbox backend.
+    ///
+    /// `base_url` should be the root of the OpenSandbox API (e.g.
+    /// `"http://localhost:8080"`). `api_key` is optional and sent as
+    /// `Authorization: Bearer <key>` when set. `timeout_secs` controls the
+    /// HTTP request timeout.
+    #[must_use]
+    pub fn new(base_url: String, api_key: Option<String>, timeout_secs: u64) -> Self {
+        let client = reqwest::Client::builder()
+            .timeout(Duration::from_secs(timeout_secs))
+            .build()
+            .expect("reqwest::Client::builder should not fail with default settings");
+
+        Self {
+            base_url,
+            api_key,
+            timeout_secs,
+            client,
+        }
+    }
+
+    /// Build the full URL for the sandbox run endpoint.
+    fn run_url(&self) -> String {
+        format!("{}/v1/sandbox/run", self.base_url.trim_end_matches('/'))
+    }
+}
+
+#[async_trait]
+impl SandboxBackend for OpenSandboxBackend {
+    async fn exec(
+        &self,
+        cmd: &str,
+        env: &HashMap<String, String>,
+    ) -> Result<SandboxOutput> {
+        let request_body = SandboxRunRequest {
+            cmd: cmd.to_string(),
+            env: env.clone(),
+        };
+
+        let mut req = self
+            .client
+            .post(self.run_url())
+            .json(&request_body);
+
+        if let Some(ref api_key) = self.api_key {
+            req = req.bearer_auth(api_key);
+        }
+
+        let response = req
+            .send()
+            .await
+            .context("Failed to reach OpenSandbox endpoint")?;
+
+        let status = response.status();
+        if !status.is_success() {
+            let body = response.text().await.unwrap_or_default();
+            anyhow::bail!(
+                "OpenSandbox returned HTTP {}: {}",
+                status.as_u16(),
+                body
+            );
+        }
+
+        let parsed: SandboxRunResponse = response
+            .json()
+            .await
+            .context("Failed to parse OpenSandbox response")?;
+
+        Ok(SandboxOutput {
+            stdout: parsed.stdout,
+            stderr: parsed.stderr,
+            exit_code: parsed.exit_code,
+        })
+    }
+}
diff --git a/crates/tui/src/tools/shell.rs b/crates/tui/src/tools/shell.rs
index d46c1727..b622e701 100644
--- a/crates/tui/src/tools/shell.rs
+++ b/crates/tui/src/tools/shell.rs
@@ -1679,6 +1679,107 @@ impl ToolSpec for ExecShellTool {
             std::collections::HashMap::new()
         };
 
+        // Route through external sandbox backend when configured.
+        if let Some(backend) = &context.sandbox_backend {
+            if interactive {
+                return Ok(ToolResult::error(
+                    "Interactive mode is not supported with external sandbox backends.",
+                ));
+            }
+            if background {
+                return Ok(ToolResult::error(
+                    "Background mode is not supported with external sandbox backends.",
+                ));
+            }
+            if tty {
+                return Ok(ToolResult::error(
+                    "TTY mode is not supported with external sandbox backends.",
+                ));
+            }
+
+            let started = std::time::Instant::now();
+            let backend_result = backend.exec(command, &extra_env).await;
+
+            let result = match backend_result {
+                Ok(output) => {
+                    let (stdout, stdout_meta) = truncate_with_meta(&output.stdout);
+                    let (stderr, stderr_meta) = truncate_with_meta(&output.stderr);
+                    ShellResult {
+                        task_id: None,
+                        status: if output.exit_code == 0 {
+                            ShellStatus::Completed
+                        } else {
+                            ShellStatus::Failed
+                        },
+                        exit_code: Some(output.exit_code),
+                        stdout,
+                        stderr,
+                        duration_ms: u64::try_from(started.elapsed().as_millis())
+                            .unwrap_or(u64::MAX),
+                        stdout_len: stdout_meta.original_len,
+                        stderr_len: stderr_meta.original_len,
+                        stdout_omitted: stdout_meta.omitted,
+                        stderr_omitted: stderr_meta.omitted,
+                        stdout_truncated: stdout_meta.truncated,
+                        stderr_truncated: stderr_meta.truncated,
+                        sandboxed: true,
+                        sandbox_type: Some("opensandbox".to_string()),
+                        sandbox_denied: false,
+                    }
+                }
+                Err(e) => {
+                    return Ok(ToolResult::error(format!(
+                        "Sandbox backend error: {e}"
+                    )));
+                }
+            };
+
+            // Build result (reuse the existing output rendering below).
+            let stdout_summary = summarize_output(&result.stdout);
+            let stderr_summary = summarize_output(&result.stderr);
+            let summary = if !stderr_summary.is_empty() {
+                stderr_summary.clone()
+            } else {
+                stdout_summary.clone()
+            };
+            let output = if result.stdout.is_empty() && result.stderr.is_empty() {
+                "(no output)".to_string()
+            } else if result.stderr.is_empty() {
+                result.stdout.clone()
+            } else {
+                format!("{}\n\nSTDERR:\n{}", result.stdout, result.stderr)
+            };
+
+            let metadata = json!({
+                "exit_code": result.exit_code,
+                "status": format!("{:?}", result.status),
+                "duration_ms": result.duration_ms,
+                "sandboxed": true,
+                "sandbox_type": "opensandbox",
+                "sandbox_denied": false,
+                "task_id": result.task_id,
+                "stdout_len": result.stdout_len,
+                "stderr_len": result.stderr_len,
+                "stdout_truncated": result.stdout_truncated,
+                "stderr_truncated": result.stderr_truncated,
+                "stdout_omitted": result.stdout_omitted,
+                "stderr_omitted": result.stderr_omitted,
+                "summary": summary,
+                "stdout_summary": stdout_summary,
+                "stderr_summary": stderr_summary,
+                "safety_level": format!("{:?}", safety.level),
+                "interactive": false,
+                "canceled": false,
+                "sandbox_backend": "opensandbox",
+            });
+
+            return Ok(ToolResult {
+                content: output,
+                success: result.status == ShellStatus::Completed,
+                metadata: Some(metadata),
+            });
+        }
+
         let result = if interactive {
             let mut manager = context
                 .shell_manager
diff --git a/crates/tui/src/tools/spec.rs b/crates/tui/src/tools/spec.rs
index 745c781c..052fb9c4 100644
--- a/crates/tui/src/tools/spec.rs
+++ b/crates/tui/src/tools/spec.rs
@@ -16,6 +16,7 @@ use tokio_util::sync::CancellationToken;
 use crate::features::Features;
 use crate::lsp::LspManager;
 use crate::network_policy::NetworkPolicyDecider;
+use crate::sandbox::backend::SandboxBackend;
 use crate::tools::shell::{SharedShellManager, new_shared_shell_manager};
 #[allow(unused_imports)]
 pub use deepseek_tools::{
@@ -107,6 +108,10 @@ pub struct ToolContext {
     /// Cancellation token for the active engine turn. Tools that may wait on
     /// external work should observe this so UI cancel can interrupt them.
     pub cancel_token: Option<CancellationToken>,
+    /// Optional external sandbox backend for shell execution.
+    /// When set, exec_shell routes commands through this instead of spawning
+    /// a local process.
+    pub sandbox_backend: Option<std::sync::Arc<dyn SandboxBackend>>,
     /// Path to the user memory file. `None` when the user-memory feature
     /// (#489) is disabled — tools that read or write the file should
     /// short-circuit on `None` rather than fall back to a workspace-local
@@ -153,6 +158,7 @@ impl ToolContext {
             network_policy: None,
             runtime: RuntimeToolServices::default(),
             cancel_token: None,
+            sandbox_backend: None,
             memory_path: None,
             lsp_manager: None,
             large_output_router: None,
@@ -185,6 +191,7 @@ impl ToolContext {
             network_policy: None,
             runtime: RuntimeToolServices::default(),
             cancel_token: None,
+            sandbox_backend: None,
             memory_path: None,
             lsp_manager: None,
             large_output_router: None,
@@ -217,6 +224,7 @@ impl ToolContext {
             network_policy: None,
             runtime: RuntimeToolServices::default(),
             cancel_token: None,
+            sandbox_backend: None,
             memory_path: None,
             lsp_manager: None,
             large_output_router: None,
@@ -245,6 +253,14 @@ impl ToolContext {
         self
     }
 
+    /// Attach an external sandbox backend for remote shell execution.
+    #[must_use]
+    #[allow(dead_code)]
+    pub fn with_sandbox_backend(mut self, backend: std::sync::Arc<dyn SandboxBackend>) -> Self {
+        self.sandbox_backend = Some(backend);
+        self
+    }
+
     /// Set the user's trusted external paths (loaded from
     /// `~/.deepseek/workspace-trust.json`). See [`Self::resolve_path`] for
     /// how the list is consulted.