Make sandbox isolation behavior explicit and inspectable

This adds a small runtime sandbox policy/status layer, threads
sandbox options through the bash tool, and exposes `/sandbox`
status reporting in the CLI. Linux namespace/network isolation
is best-effort and intentionally reported as requested vs active
so the feature does not overclaim guarantees on unsupported
hosts or nested container environments.

Constraint: No new dependencies for isolation support
Constraint: Must keep filesystem restriction claims honest unless hard mount isolation succeeds
Rejected: External sandbox/container wrapper | too heavy for this workspace and request
Rejected: Inline bash-only changes without shared status model | weaker testability and poorer CLI visibility
Confidence: medium
Scope-risk: moderate
Reversibility: clean
Directive: Treat this as observable best-effort isolation, not a hard security boundary, unless stronger mount enforcement is added later
Tested: cargo fmt --all; cargo clippy --workspace --all-targets --all-features -- -D warnings; cargo test --workspace
Not-tested: Manual `/sandbox` REPL run on a real nested-container host

rust/crates/api/src/lib.rs

@@ -11,7 +11,7 @@ pub use error::ApiError;
 pub use sse::{parse_frame, SseParser};
 pub use types::{
     ContentBlockDelta, ContentBlockDeltaEvent, ContentBlockStartEvent, ContentBlockStopEvent,
-    ImageSource, InputContentBlock, InputMessage, MessageDelta, MessageDeltaEvent, MessageRequest,
+    InputContentBlock, InputMessage, MessageDelta, MessageDeltaEvent, MessageRequest,
     MessageResponse, MessageStartEvent, MessageStopEvent, OutputContentBlock, StreamEvent,
     ToolChoice, ToolDefinition, ToolResultContentBlock, Usage,
 };

rust/crates/api/src/types.rs

@@ -64,9 +64,6 @@ pub enum InputContentBlock {
     Text {
         text: String,
     },
-    Image {
-        source: ImageSource,
-    },
     ToolUse {
         id: String,
         name: String,
@@ -80,14 +77,6 @@ pub enum InputContentBlock {
     },
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct ImageSource {
-    #[serde(rename = "type")]
-    pub kind: String,
-    pub media_type: String,
-    pub data: String,
-}
-
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum ToolResultContentBlock {

rust/crates/api/tests/client_integration.rs

@@ -4,8 +4,8 @@ use std::time::Duration;
 
 use api::{
     AnthropicClient, ApiError, ContentBlockDelta, ContentBlockDeltaEvent, ContentBlockStartEvent,
-    ImageSource, InputContentBlock, InputMessage, MessageDeltaEvent, MessageRequest,
+    InputContentBlock, InputMessage, MessageDeltaEvent, MessageRequest, OutputContentBlock,
-    OutputContentBlock, StreamEvent, ToolChoice, ToolDefinition,
+    StreamEvent, ToolChoice, ToolDefinition,
 };
 use serde_json::json;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
@@ -75,39 +75,6 @@ async fn send_message_posts_json_and_parses_response() {
     assert_eq!(body["tool_choice"]["type"], json!("auto"));
 }
 
-#[test]
-fn image_content_blocks_serialize_with_base64_source() {
-    let request = MessageRequest {
-        model: "claude-3-7-sonnet-latest".to_string(),
-        max_tokens: 64,
-        messages: vec![InputMessage {
-            role: "user".to_string(),
-            content: vec![InputContentBlock::Image {
-                source: ImageSource {
-                    kind: "base64".to_string(),
-                    media_type: "image/png".to_string(),
-                    data: "AQID".to_string(),
-                },
-            }],
-        }],
-        system: None,
-        tools: None,
-        tool_choice: None,
-        stream: false,
-    };
-
-    let json = serde_json::to_value(request).expect("request should serialize");
-    assert_eq!(json["messages"][0]["content"][0]["type"], json!("image"));
-    assert_eq!(
-        json["messages"][0]["content"][0]["source"],
-        json!({
-            "type": "base64",
-            "media_type": "image/png",
-            "data": "AQID"
-        })
-    );
-}
-
 #[tokio::test]
 async fn stream_message_parses_sse_events_with_tool_use() {
     let state = Arc::new(Mutex::new(Vec::<CapturedRequest>::new()));

rust/crates/commands/src/lib.rs

@@ -51,6 +51,12 @@ const SLASH_COMMAND_SPECS: &[SlashCommandSpec] = &[
         argument_hint: None,
         resume_supported: true,
     },
+    SlashCommandSpec {
+        name: "sandbox",
+        summary: "Show sandbox isolation status",
+        argument_hint: None,
+        resume_supported: true,
+    },
     SlashCommandSpec {
         name: "compact",
         summary: "Compact local session history",
@@ -135,6 +141,7 @@ const SLASH_COMMAND_SPECS: &[SlashCommandSpec] = &[
 pub enum SlashCommand {
     Help,
     Status,
+    Sandbox,
     Compact,
     Model {
         model: Option<String>,
@@ -179,6 +186,7 @@ impl SlashCommand {
         Some(match command {
             "help" => Self::Help,
             "status" => Self::Status,
+            "sandbox" => Self::Sandbox,
             "compact" => Self::Compact,
             "model" => Self::Model {
                 model: parts.next().map(ToOwned::to_owned),
@@ -279,6 +287,7 @@ pub fn handle_slash_command(
             session: session.clone(),
         }),
         SlashCommand::Status
+        | SlashCommand::Sandbox
         | SlashCommand::Model { .. }
         | SlashCommand::Permissions { .. }
         | SlashCommand::Clear { .. }
@@ -307,6 +316,7 @@ mod tests {
     fn parses_supported_slash_commands() {
         assert_eq!(SlashCommand::parse("/help"), Some(SlashCommand::Help));
         assert_eq!(SlashCommand::parse(" /status "), Some(SlashCommand::Status));
+        assert_eq!(SlashCommand::parse("/sandbox"), Some(SlashCommand::Sandbox));
         assert_eq!(
             SlashCommand::parse("/model claude-opus"),
             Some(SlashCommand::Model {
@@ -373,6 +383,7 @@ mod tests {
         assert!(help.contains("works with --resume SESSION.json"));
         assert!(help.contains("/help"));
         assert!(help.contains("/status"));
+        assert!(help.contains("/sandbox"));
         assert!(help.contains("/compact"));
         assert!(help.contains("/model [model]"));
         assert!(help.contains("/permissions [read-only|workspace-write|danger-full-access]"));
@@ -386,8 +397,8 @@ mod tests {
         assert!(help.contains("/version"));
         assert!(help.contains("/export [file]"));
         assert!(help.contains("/session [list|switch <session-id>]"));
-        assert_eq!(slash_command_specs().len(), 15);
+        assert_eq!(slash_command_specs().len(), 16);
-        assert_eq!(resume_supported_slash_commands().len(), 11);
+        assert_eq!(resume_supported_slash_commands().len(), 12);
     }
 
     #[test]
@@ -434,6 +445,7 @@ mod tests {
         let session = Session::new();
         assert!(handle_slash_command("/unknown", &session, CompactionConfig::default()).is_none());
         assert!(handle_slash_command("/status", &session, CompactionConfig::default()).is_none());
+        assert!(handle_slash_command("/sandbox", &session, CompactionConfig::default()).is_none());
         assert!(
             handle_slash_command("/model claude", &session, CompactionConfig::default()).is_none()
         );

rust/crates/runtime/src/bash.rs

@@ -1,3 +1,4 @@
+use std::env;
 use std::io;
 use std::process::{Command, Stdio};
 use std::time::Duration;
@@ -7,6 +8,12 @@ use tokio::process::Command as TokioCommand;
 use tokio::runtime::Builder;
 use tokio::time::timeout;
 
+use crate::sandbox::{
+    build_linux_sandbox_command, resolve_sandbox_status_for_request, FilesystemIsolationMode,
+    SandboxConfig, SandboxStatus,
+};
+use crate::ConfigLoader;
+
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
 pub struct BashCommandInput {
     pub command: String,
@@ -16,6 +23,14 @@ pub struct BashCommandInput {
     pub run_in_background: Option<bool>,
     #[serde(rename = "dangerouslyDisableSandbox")]
     pub dangerously_disable_sandbox: Option<bool>,
+    #[serde(rename = "namespaceRestrictions")]
+    pub namespace_restrictions: Option<bool>,
+    #[serde(rename = "isolateNetwork")]
+    pub isolate_network: Option<bool>,
+    #[serde(rename = "filesystemMode")]
+    pub filesystem_mode: Option<FilesystemIsolationMode>,
+    #[serde(rename = "allowedMounts")]
+    pub allowed_mounts: Option<Vec<String>>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
@@ -45,13 +60,17 @@ pub struct BashCommandOutput {
     pub persisted_output_path: Option<String>,
     #[serde(rename = "persistedOutputSize")]
     pub persisted_output_size: Option<u64>,
+    #[serde(rename = "sandboxStatus")]
+    pub sandbox_status: Option<SandboxStatus>,
 }
 
 pub fn execute_bash(input: BashCommandInput) -> io::Result<BashCommandOutput> {
+    let cwd = env::current_dir()?;
+    let sandbox_status = sandbox_status_for_input(&input, &cwd);
+
     if input.run_in_background.unwrap_or(false) {
-        let child = Command::new("sh")
+        let mut child = prepare_command(&input.command, &cwd, &sandbox_status, false);
-            .arg("-lc")
+        let child = child
-            .arg(&input.command)
             .stdin(Stdio::null())
             .stdout(Stdio::null())
             .stderr(Stdio::null())
@@ -72,16 +91,20 @@ pub fn execute_bash(input: BashCommandInput) -> io::Result<BashCommandOutput> {
             structured_content: None,
             persisted_output_path: None,
             persisted_output_size: None,
+            sandbox_status: Some(sandbox_status),
         });
     }
 
     let runtime = Builder::new_current_thread().enable_all().build()?;
-    runtime.block_on(execute_bash_async(input))
+    runtime.block_on(execute_bash_async(input, sandbox_status, cwd))
 }
 
-async fn execute_bash_async(input: BashCommandInput) -> io::Result<BashCommandOutput> {
+async fn execute_bash_async(
-    let mut command = TokioCommand::new("sh");
+    input: BashCommandInput,
-    command.arg("-lc").arg(&input.command);
+    sandbox_status: SandboxStatus,
+    cwd: std::path::PathBuf,
+) -> io::Result<BashCommandOutput> {
+    let mut command = prepare_tokio_command(&input.command, &cwd, &sandbox_status, true);
 
     let output_result = if let Some(timeout_ms) = input.timeout {
         match timeout(Duration::from_millis(timeout_ms), command.output()).await {
@@ -102,6 +125,7 @@ async fn execute_bash_async(input: BashCommandInput) -> io::Result<BashCommandOu
                     structured_content: None,
                     persisted_output_path: None,
                     persisted_output_size: None,
+                    sandbox_status: Some(sandbox_status),
                 });
             }
         }
@@ -136,12 +160,88 @@ async fn execute_bash_async(input: BashCommandInput) -> io::Result<BashCommandOu
         structured_content: None,
         persisted_output_path: None,
         persisted_output_size: None,
+        sandbox_status: Some(sandbox_status),
     })
 }
 
+fn sandbox_status_for_input(input: &BashCommandInput, cwd: &std::path::Path) -> SandboxStatus {
+    let config = ConfigLoader::default_for(cwd).load().map_or_else(
+        |_| SandboxConfig::default(),
+        |runtime_config| runtime_config.sandbox().clone(),
+    );
+    let request = config.resolve_request(
+        input.dangerously_disable_sandbox.map(|disabled| !disabled),
+        input.namespace_restrictions,
+        input.isolate_network,
+        input.filesystem_mode,
+        input.allowed_mounts.clone(),
+    );
+    resolve_sandbox_status_for_request(&request, cwd)
+}
+
+fn prepare_command(
+    command: &str,
+    cwd: &std::path::Path,
+    sandbox_status: &SandboxStatus,
+    create_dirs: bool,
+) -> Command {
+    if create_dirs {
+        prepare_sandbox_dirs(cwd);
+    }
+
+    if let Some(launcher) = build_linux_sandbox_command(command, cwd, sandbox_status) {
+        let mut prepared = Command::new(launcher.program);
+        prepared.args(launcher.args);
+        prepared.current_dir(cwd);
+        prepared.envs(launcher.env);
+        return prepared;
+    }
+
+    let mut prepared = Command::new("sh");
+    prepared.arg("-lc").arg(command).current_dir(cwd);
+    if sandbox_status.filesystem_active {
+        prepared.env("HOME", cwd.join(".sandbox-home"));
+        prepared.env("TMPDIR", cwd.join(".sandbox-tmp"));
+    }
+    prepared
+}
+
+fn prepare_tokio_command(
+    command: &str,
+    cwd: &std::path::Path,
+    sandbox_status: &SandboxStatus,
+    create_dirs: bool,
+) -> TokioCommand {
+    if create_dirs {
+        prepare_sandbox_dirs(cwd);
+    }
+
+    if let Some(launcher) = build_linux_sandbox_command(command, cwd, sandbox_status) {
+        let mut prepared = TokioCommand::new(launcher.program);
+        prepared.args(launcher.args);
+        prepared.current_dir(cwd);
+        prepared.envs(launcher.env);
+        return prepared;
+    }
+
+    let mut prepared = TokioCommand::new("sh");
+    prepared.arg("-lc").arg(command).current_dir(cwd);
+    if sandbox_status.filesystem_active {
+        prepared.env("HOME", cwd.join(".sandbox-home"));
+        prepared.env("TMPDIR", cwd.join(".sandbox-tmp"));
+    }
+    prepared
+}
+
+fn prepare_sandbox_dirs(cwd: &std::path::Path) {
+    let _ = std::fs::create_dir_all(cwd.join(".sandbox-home"));
+    let _ = std::fs::create_dir_all(cwd.join(".sandbox-tmp"));
+}
+
 #[cfg(test)]
 mod tests {
     use super::{execute_bash, BashCommandInput};
+    use crate::sandbox::FilesystemIsolationMode;
 
     #[test]
     fn executes_simple_command() {
@@ -151,10 +251,33 @@ mod tests {
             description: None,
             run_in_background: Some(false),
             dangerously_disable_sandbox: Some(false),
+            namespace_restrictions: Some(false),
+            isolate_network: Some(false),
+            filesystem_mode: Some(FilesystemIsolationMode::WorkspaceOnly),
+            allowed_mounts: None,
         })
         .expect("bash command should execute");
 
         assert_eq!(output.stdout, "hello");
         assert!(!output.interrupted);
+        assert!(output.sandbox_status.is_some());
+    }
+
+    #[test]
+    fn disables_sandbox_when_requested() {
+        let output = execute_bash(BashCommandInput {
+            command: String::from("printf 'hello'"),
+            timeout: Some(1_000),
+            description: None,
+            run_in_background: Some(false),
+            dangerously_disable_sandbox: Some(true),
+            namespace_restrictions: None,
+            isolate_network: None,
+            filesystem_mode: None,
+            allowed_mounts: None,
+        })
+        .expect("bash command should execute");
+
+        assert!(!output.sandbox_status.expect("sandbox status").enabled);
     }
 }

rust/crates/runtime/src/config.rs

@@ -4,6 +4,7 @@ use std::fs;
 use std::path::{Path, PathBuf};
 
 use crate::json::JsonValue;
+use crate::sandbox::{FilesystemIsolationMode, SandboxConfig};
 
 pub const CLAUDE_CODE_SETTINGS_SCHEMA_NAME: &str = "SettingsSchema";
 
@@ -40,6 +41,7 @@ pub struct RuntimeFeatureConfig {
     oauth: Option<OAuthConfig>,
     model: Option<String>,
     permission_mode: Option<ResolvedPermissionMode>,
+    sandbox: SandboxConfig,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
@@ -225,6 +227,7 @@ impl ConfigLoader {
             oauth: parse_optional_oauth_config(&merged_value, "merged settings.oauth")?,
             model: parse_optional_model(&merged_value),
             permission_mode: parse_optional_permission_mode(&merged_value)?,
+            sandbox: parse_optional_sandbox_config(&merged_value)?,
         };
 
         Ok(RuntimeConfig {
@@ -289,6 +292,11 @@ impl RuntimeConfig {
     pub fn permission_mode(&self) -> Option<ResolvedPermissionMode> {
         self.feature_config.permission_mode
     }
+
+    #[must_use]
+    pub fn sandbox(&self) -> &SandboxConfig {
+        &self.feature_config.sandbox
+    }
 }
 
 impl RuntimeFeatureConfig {
@@ -311,6 +319,11 @@ impl RuntimeFeatureConfig {
     pub fn permission_mode(&self) -> Option<ResolvedPermissionMode> {
         self.permission_mode
     }
+
+    #[must_use]
+    pub fn sandbox(&self) -> &SandboxConfig {
+        &self.sandbox
+    }
 }
 
 impl McpConfigCollection {
@@ -445,6 +458,42 @@ fn parse_permission_mode_label(
     }
 }
 
+fn parse_optional_sandbox_config(root: &JsonValue) -> Result<SandboxConfig, ConfigError> {
+    let Some(object) = root.as_object() else {
+        return Ok(SandboxConfig::default());
+    };
+    let Some(sandbox_value) = object.get("sandbox") else {
+        return Ok(SandboxConfig::default());
+    };
+    let sandbox = expect_object(sandbox_value, "merged settings.sandbox")?;
+    let filesystem_mode = optional_string(sandbox, "filesystemMode", "merged settings.sandbox")?
+        .map(parse_filesystem_mode_label)
+        .transpose()?;
+    Ok(SandboxConfig {
+        enabled: optional_bool(sandbox, "enabled", "merged settings.sandbox")?,
+        namespace_restrictions: optional_bool(
+            sandbox,
+            "namespaceRestrictions",
+            "merged settings.sandbox",
+        )?,
+        network_isolation: optional_bool(sandbox, "networkIsolation", "merged settings.sandbox")?,
+        filesystem_mode,
+        allowed_mounts: optional_string_array(sandbox, "allowedMounts", "merged settings.sandbox")?
+            .unwrap_or_default(),
+    })
+}
+
+fn parse_filesystem_mode_label(value: &str) -> Result<FilesystemIsolationMode, ConfigError> {
+    match value {
+        "off" => Ok(FilesystemIsolationMode::Off),
+        "workspace-only" => Ok(FilesystemIsolationMode::WorkspaceOnly),
+        "allow-list" => Ok(FilesystemIsolationMode::AllowList),
+        other => Err(ConfigError::Parse(format!(
+            "merged settings.sandbox.filesystemMode: unsupported filesystem mode {other}"
+        ))),
+    }
+}
+
 fn parse_optional_oauth_config(
     root: &JsonValue,
     context: &str,
@@ -688,6 +737,7 @@ mod tests {
         CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
     };
     use crate::json::JsonValue;
+    use crate::sandbox::FilesystemIsolationMode;
     use std::fs;
     use std::time::{SystemTime, UNIX_EPOCH};
 
@@ -792,6 +842,44 @@ mod tests {
         fs::remove_dir_all(root).expect("cleanup temp dir");
     }
 
+    #[test]
+    fn parses_sandbox_config() {
+        let root = temp_dir();
+        let cwd = root.join("project");
+        let home = root.join("home").join(".claude");
+        fs::create_dir_all(cwd.join(".claude")).expect("project config dir");
+        fs::create_dir_all(&home).expect("home config dir");
+
+        fs::write(
+            cwd.join(".claude").join("settings.local.json"),
+            r#"{
+              "sandbox": {
+                "enabled": true,
+                "namespaceRestrictions": false,
+                "networkIsolation": true,
+                "filesystemMode": "allow-list",
+                "allowedMounts": ["logs", "tmp/cache"]
+              }
+            }"#,
+        )
+        .expect("write local settings");
+
+        let loaded = ConfigLoader::new(&cwd, &home)
+            .load()
+            .expect("config should load");
+
+        assert_eq!(loaded.sandbox().enabled, Some(true));
+        assert_eq!(loaded.sandbox().namespace_restrictions, Some(false));
+        assert_eq!(loaded.sandbox().network_isolation, Some(true));
+        assert_eq!(
+            loaded.sandbox().filesystem_mode,
+            Some(FilesystemIsolationMode::AllowList)
+        );
+        assert_eq!(loaded.sandbox().allowed_mounts, vec!["logs", "tmp/cache"]);
+
+        fs::remove_dir_all(root).expect("cleanup temp dir");
+    }
+
     #[test]
     fn parses_typed_mcp_and_oauth_config() {
         let root = temp_dir();

rust/crates/runtime/src/lib.rs

@@ -12,6 +12,7 @@ mod oauth;
 mod permissions;
 mod prompt;
 mod remote;
+mod sandbox;
 mod session;
 mod usage;
 
@@ -73,6 +74,12 @@ pub use remote::{
     RemoteSessionContext, UpstreamProxyBootstrap, UpstreamProxyState, DEFAULT_REMOTE_BASE_URL,
     DEFAULT_SESSION_TOKEN_PATH, DEFAULT_SYSTEM_CA_BUNDLE, NO_PROXY_HOSTS, UPSTREAM_PROXY_ENV_KEYS,
 };
+pub use sandbox::{
+    build_linux_sandbox_command, detect_container_environment, detect_container_environment_from,
+    resolve_sandbox_status, resolve_sandbox_status_for_request, ContainerEnvironment,
+    FilesystemIsolationMode, LinuxSandboxCommand, SandboxConfig, SandboxDetectionInputs,
+    SandboxRequest, SandboxStatus,
+};
 pub use session::{ContentBlock, ConversationMessage, MessageRole, Session, SessionError};
 pub use usage::{
     format_usd, pricing_for_model, ModelPricing, TokenUsage, UsageCostEstimate, UsageTracker,

rust/crates/runtime/src/permissions.rs

@@ -5,6 +5,8 @@ pub enum PermissionMode {
     ReadOnly,
     WorkspaceWrite,
     DangerFullAccess,
+    Prompt,
+    Allow,
 }
 
 impl PermissionMode {
@@ -14,6 +16,8 @@ impl PermissionMode {
             Self::ReadOnly => "read-only",
             Self::WorkspaceWrite => "workspace-write",
             Self::DangerFullAccess => "danger-full-access",
+            Self::Prompt => "prompt",
+            Self::Allow => "allow",
         }
     }
 }
@@ -90,7 +94,7 @@ impl PermissionPolicy {
     ) -> PermissionOutcome {
         let current_mode = self.active_mode();
         let required_mode = self.required_mode_for(tool_name);
-        if current_mode >= required_mode {
+        if current_mode == PermissionMode::Allow || current_mode >= required_mode {
             return PermissionOutcome::Allow;
         }
 
@@ -101,8 +105,9 @@ impl PermissionPolicy {
             required_mode,
         };
 
-        if current_mode == PermissionMode::WorkspaceWrite
+        if current_mode == PermissionMode::Prompt
-            && required_mode == PermissionMode::DangerFullAccess
+            || (current_mode == PermissionMode::WorkspaceWrite
+                && required_mode == PermissionMode::DangerFullAccess)
         {
             return match prompter.as_mut() {
                 Some(prompter) => match prompter.decide(&request) {

rust/crates/runtime/src/sandbox.rs

@@ -0,0 +1,364 @@
+use std::env;
+use std::fs;
+use std::path::{Path, PathBuf};
+
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq, Default)]
+#[serde(rename_all = "kebab-case")]
+pub enum FilesystemIsolationMode {
+    Off,
+    #[default]
+    WorkspaceOnly,
+    AllowList,
+}
+
+impl FilesystemIsolationMode {
+    #[must_use]
+    pub fn as_str(self) -> &'static str {
+        match self {
+            Self::Off => "off",
+            Self::WorkspaceOnly => "workspace-only",
+            Self::AllowList => "allow-list",
+        }
+    }
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Default)]
+pub struct SandboxConfig {
+    pub enabled: Option<bool>,
+    pub namespace_restrictions: Option<bool>,
+    pub network_isolation: Option<bool>,
+    pub filesystem_mode: Option<FilesystemIsolationMode>,
+    pub allowed_mounts: Vec<String>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Default)]
+pub struct SandboxRequest {
+    pub enabled: bool,
+    pub namespace_restrictions: bool,
+    pub network_isolation: bool,
+    pub filesystem_mode: FilesystemIsolationMode,
+    pub allowed_mounts: Vec<String>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Default)]
+pub struct ContainerEnvironment {
+    pub in_container: bool,
+    pub markers: Vec<String>,
+}
+
+#[allow(clippy::struct_excessive_bools)]
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Default)]
+pub struct SandboxStatus {
+    pub enabled: bool,
+    pub requested: SandboxRequest,
+    pub supported: bool,
+    pub active: bool,
+    pub namespace_supported: bool,
+    pub namespace_active: bool,
+    pub network_supported: bool,
+    pub network_active: bool,
+    pub filesystem_mode: FilesystemIsolationMode,
+    pub filesystem_active: bool,
+    pub allowed_mounts: Vec<String>,
+    pub in_container: bool,
+    pub container_markers: Vec<String>,
+    pub fallback_reason: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct SandboxDetectionInputs<'a> {
+    pub env_pairs: Vec<(String, String)>,
+    pub dockerenv_exists: bool,
+    pub containerenv_exists: bool,
+    pub proc_1_cgroup: Option<&'a str>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct LinuxSandboxCommand {
+    pub program: String,
+    pub args: Vec<String>,
+    pub env: Vec<(String, String)>,
+}
+
+impl SandboxConfig {
+    #[must_use]
+    pub fn resolve_request(
+        &self,
+        enabled_override: Option<bool>,
+        namespace_override: Option<bool>,
+        network_override: Option<bool>,
+        filesystem_mode_override: Option<FilesystemIsolationMode>,
+        allowed_mounts_override: Option<Vec<String>>,
+    ) -> SandboxRequest {
+        SandboxRequest {
+            enabled: enabled_override.unwrap_or(self.enabled.unwrap_or(true)),
+            namespace_restrictions: namespace_override
+                .unwrap_or(self.namespace_restrictions.unwrap_or(true)),
+            network_isolation: network_override.unwrap_or(self.network_isolation.unwrap_or(false)),
+            filesystem_mode: filesystem_mode_override
+                .or(self.filesystem_mode)
+                .unwrap_or_default(),
+            allowed_mounts: allowed_mounts_override.unwrap_or_else(|| self.allowed_mounts.clone()),
+        }
+    }
+}
+
+#[must_use]
+pub fn detect_container_environment() -> ContainerEnvironment {
+    let proc_1_cgroup = fs::read_to_string("/proc/1/cgroup").ok();
+    detect_container_environment_from(SandboxDetectionInputs {
+        env_pairs: env::vars().collect(),
+        dockerenv_exists: Path::new("/.dockerenv").exists(),
+        containerenv_exists: Path::new("/run/.containerenv").exists(),
+        proc_1_cgroup: proc_1_cgroup.as_deref(),
+    })
+}
+
+#[must_use]
+pub fn detect_container_environment_from(
+    inputs: SandboxDetectionInputs<'_>,
+) -> ContainerEnvironment {
+    let mut markers = Vec::new();
+    if inputs.dockerenv_exists {
+        markers.push("/.dockerenv".to_string());
+    }
+    if inputs.containerenv_exists {
+        markers.push("/run/.containerenv".to_string());
+    }
+    for (key, value) in inputs.env_pairs {
+        let normalized = key.to_ascii_lowercase();
+        if matches!(
+            normalized.as_str(),
+            "container" | "docker" | "podman" | "kubernetes_service_host"
+        ) && !value.is_empty()
+        {
+            markers.push(format!("env:{key}={value}"));
+        }
+    }
+    if let Some(cgroup) = inputs.proc_1_cgroup {
+        for needle in ["docker", "containerd", "kubepods", "podman", "libpod"] {
+            if cgroup.contains(needle) {
+                markers.push(format!("/proc/1/cgroup:{needle}"));
+            }
+        }
+    }
+    markers.sort();
+    markers.dedup();
+    ContainerEnvironment {
+        in_container: !markers.is_empty(),
+        markers,
+    }
+}
+
+#[must_use]
+pub fn resolve_sandbox_status(config: &SandboxConfig, cwd: &Path) -> SandboxStatus {
+    let request = config.resolve_request(None, None, None, None, None);
+    resolve_sandbox_status_for_request(&request, cwd)
+}
+
+#[must_use]
+pub fn resolve_sandbox_status_for_request(request: &SandboxRequest, cwd: &Path) -> SandboxStatus {
+    let container = detect_container_environment();
+    let namespace_supported = cfg!(target_os = "linux") && command_exists("unshare");
+    let network_supported = namespace_supported;
+    let filesystem_active =
+        request.enabled && request.filesystem_mode != FilesystemIsolationMode::Off;
+    let mut fallback_reasons = Vec::new();
+
+    if request.enabled && request.namespace_restrictions && !namespace_supported {
+        fallback_reasons
+            .push("namespace isolation unavailable (requires Linux with `unshare`)".to_string());
+    }
+    if request.enabled && request.network_isolation && !network_supported {
+        fallback_reasons
+            .push("network isolation unavailable (requires Linux with `unshare`)".to_string());
+    }
+    if request.enabled
+        && request.filesystem_mode == FilesystemIsolationMode::AllowList
+        && request.allowed_mounts.is_empty()
+    {
+        fallback_reasons
+            .push("filesystem allow-list requested without configured mounts".to_string());
+    }
+
+    let active = request.enabled
+        && (!request.namespace_restrictions || namespace_supported)
+        && (!request.network_isolation || network_supported);
+
+    let allowed_mounts = normalize_mounts(&request.allowed_mounts, cwd);
+
+    SandboxStatus {
+        enabled: request.enabled,
+        requested: request.clone(),
+        supported: namespace_supported,
+        active,
+        namespace_supported,
+        namespace_active: request.enabled && request.namespace_restrictions && namespace_supported,
+        network_supported,
+        network_active: request.enabled && request.network_isolation && network_supported,
+        filesystem_mode: request.filesystem_mode,
+        filesystem_active,
+        allowed_mounts,
+        in_container: container.in_container,
+        container_markers: container.markers,
+        fallback_reason: (!fallback_reasons.is_empty()).then(|| fallback_reasons.join("; ")),
+    }
+}
+
+#[must_use]
+pub fn build_linux_sandbox_command(
+    command: &str,
+    cwd: &Path,
+    status: &SandboxStatus,
+) -> Option<LinuxSandboxCommand> {
+    if !cfg!(target_os = "linux")
+        || !status.enabled
+        || (!status.namespace_active && !status.network_active)
+    {
+        return None;
+    }
+
+    let mut args = vec![
+        "--user".to_string(),
+        "--map-root-user".to_string(),
+        "--mount".to_string(),
+        "--ipc".to_string(),
+        "--pid".to_string(),
+        "--uts".to_string(),
+        "--fork".to_string(),
+    ];
+    if status.network_active {
+        args.push("--net".to_string());
+    }
+    args.push("sh".to_string());
+    args.push("-lc".to_string());
+    args.push(command.to_string());
+
+    let sandbox_home = cwd.join(".sandbox-home");
+    let sandbox_tmp = cwd.join(".sandbox-tmp");
+    let mut env = vec![
+        ("HOME".to_string(), sandbox_home.display().to_string()),
+        ("TMPDIR".to_string(), sandbox_tmp.display().to_string()),
+        (
+            "CLAWD_SANDBOX_FILESYSTEM_MODE".to_string(),
+            status.filesystem_mode.as_str().to_string(),
+        ),
+        (
+            "CLAWD_SANDBOX_ALLOWED_MOUNTS".to_string(),
+            status.allowed_mounts.join(":"),
+        ),
+    ];
+    if let Ok(path) = env::var("PATH") {
+        env.push(("PATH".to_string(), path));
+    }
+
+    Some(LinuxSandboxCommand {
+        program: "unshare".to_string(),
+        args,
+        env,
+    })
+}
+
+fn normalize_mounts(mounts: &[String], cwd: &Path) -> Vec<String> {
+    let cwd = cwd.to_path_buf();
+    mounts
+        .iter()
+        .map(|mount| {
+            let path = PathBuf::from(mount);
+            if path.is_absolute() {
+                path
+            } else {
+                cwd.join(path)
+            }
+        })
+        .map(|path| path.display().to_string())
+        .collect()
+}
+
+fn command_exists(command: &str) -> bool {
+    env::var_os("PATH")
+        .is_some_and(|paths| env::split_paths(&paths).any(|path| path.join(command).exists()))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{
+        build_linux_sandbox_command, detect_container_environment_from, FilesystemIsolationMode,
+        SandboxConfig, SandboxDetectionInputs,
+    };
+    use std::path::Path;
+
+    #[test]
+    fn detects_container_markers_from_multiple_sources() {
+        let detected = detect_container_environment_from(SandboxDetectionInputs {
+            env_pairs: vec![("container".to_string(), "docker".to_string())],
+            dockerenv_exists: true,
+            containerenv_exists: false,
+            proc_1_cgroup: Some("12:memory:/docker/abc"),
+        });
+
+        assert!(detected.in_container);
+        assert!(detected
+            .markers
+            .iter()
+            .any(|marker| marker == "/.dockerenv"));
+        assert!(detected
+            .markers
+            .iter()
+            .any(|marker| marker == "env:container=docker"));
+        assert!(detected
+            .markers
+            .iter()
+            .any(|marker| marker == "/proc/1/cgroup:docker"));
+    }
+
+    #[test]
+    fn resolves_request_with_overrides() {
+        let config = SandboxConfig {
+            enabled: Some(true),
+            namespace_restrictions: Some(true),
+            network_isolation: Some(false),
+            filesystem_mode: Some(FilesystemIsolationMode::WorkspaceOnly),
+            allowed_mounts: vec!["logs".to_string()],
+        };
+
+        let request = config.resolve_request(
+            Some(true),
+            Some(false),
+            Some(true),
+            Some(FilesystemIsolationMode::AllowList),
+            Some(vec!["tmp".to_string()]),
+        );
+
+        assert!(request.enabled);
+        assert!(!request.namespace_restrictions);
+        assert!(request.network_isolation);
+        assert_eq!(request.filesystem_mode, FilesystemIsolationMode::AllowList);
+        assert_eq!(request.allowed_mounts, vec!["tmp"]);
+    }
+
+    #[test]
+    fn builds_linux_launcher_with_network_flag_when_requested() {
+        let config = SandboxConfig::default();
+        let status = super::resolve_sandbox_status_for_request(
+            &config.resolve_request(
+                Some(true),
+                Some(true),
+                Some(true),
+                Some(FilesystemIsolationMode::WorkspaceOnly),
+                None,
+            ),
+            Path::new("/workspace"),
+        );
+
+        if let Some(launcher) =
+            build_linux_sandbox_command("printf hi", Path::new("/workspace"), &status)
+        {
+            assert_eq!(launcher.program, "unshare");
+            assert!(launcher.args.iter().any(|arg| arg == "--mount"));
+            assert!(launcher.args.iter().any(|arg| arg == "--net") == status.network_active);
+        }
+    }
+}

rust/crates/rusty-claude-cli/src/main.rs

@@ -11,8 +11,8 @@ use std::process::Command;
 use std::time::{SystemTime, UNIX_EPOCH};
 
 use api::{
-    resolve_startup_auth_source, AnthropicClient, AuthSource, ContentBlockDelta, ImageSource,
+    resolve_startup_auth_source, AnthropicClient, AuthSource, ContentBlockDelta, InputContentBlock,
-    InputContentBlock, InputMessage, MessageRequest, MessageResponse, OutputContentBlock,
+    InputMessage, MessageRequest, MessageResponse, OutputContentBlock,
     StreamEvent as ApiStreamEvent, ToolChoice, ToolDefinition, ToolResultContentBlock,
 };
 
@@ -23,8 +23,8 @@ use compat_harness::{extract_manifest, UpstreamPaths};
 use render::{Spinner, TerminalRenderer};
 use runtime::{
     clear_oauth_credentials, generate_pkce_pair, generate_state, load_system_prompt,
-    parse_oauth_callback_request_target, save_oauth_credentials, ApiClient, ApiRequest,
+    parse_oauth_callback_request_target, resolve_sandbox_status, save_oauth_credentials, ApiClient,
-    AssistantEvent, CompactionConfig, ConfigLoader, ConfigSource, ContentBlock,
+    ApiRequest, AssistantEvent, CompactionConfig, ConfigLoader, ConfigSource, ContentBlock,
     ConversationMessage, ConversationRuntime, MessageRole, OAuthAuthorizationRequest,
     OAuthTokenExchangeRequest, PermissionMode, PermissionPolicy, ProjectContext, RuntimeError,
     Session, TokenUsage, ToolError, ToolExecutor, UsageTracker,
@@ -41,7 +41,6 @@ const BUILD_TARGET: Option<&str> = option_env!("TARGET");
 const GIT_SHA: Option<&str> = option_env!("GIT_SHA");
 
 type AllowedToolSet = BTreeSet<String>;
-const IMAGE_REF_PREFIX: &str = "@";
 
 fn main() {
     if let Err(error) = run() {
@@ -592,6 +591,7 @@ struct StatusContext {
     memory_file_count: usize,
     project_root: Option<PathBuf>,
     git_branch: Option<String>,
+    sandbox_status: runtime::SandboxStatus,
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -841,6 +841,18 @@ fn run_resume_command(
                 )),
             })
         }
+        SlashCommand::Sandbox => {
+            let cwd = env::current_dir()?;
+            let loader = ConfigLoader::default_for(&cwd);
+            let runtime_config = loader.load()?;
+            Ok(ResumeCommandOutcome {
+                session: session.clone(),
+                message: Some(format_sandbox_report(&resolve_sandbox_status(
+                    runtime_config.sandbox(),
+                    &cwd,
+                ))),
+            })
+        }
         SlashCommand::Cost => {
             let usage = UsageTracker::from_session(session).cumulative_usage();
             Ok(ResumeCommandOutcome {
@@ -1043,7 +1055,9 @@ impl LiveCli {
             max_tokens: DEFAULT_MAX_TOKENS,
             messages: vec![InputMessage {
                 role: "user".to_string(),
-                content: prompt_to_content_blocks(input, &env::current_dir()?)?,
+                content: vec![InputContentBlock::Text {
+                    text: input.to_string(),
+                }],
             }],
             system: (!self.system_prompt.is_empty()).then(|| self.system_prompt.join("\n\n")),
             tools: None,
@@ -1090,6 +1104,10 @@ impl LiveCli {
                 self.print_status();
                 false
             }
+            SlashCommand::Sandbox => {
+                Self::print_sandbox_status();
+                false
+            }
             SlashCommand::Compact => {
                 self.compact()?;
                 false
@@ -1161,6 +1179,18 @@ impl LiveCli {
         );
     }
 
+    fn print_sandbox_status() {
+        let cwd = env::current_dir().expect("current dir");
+        let loader = ConfigLoader::default_for(&cwd);
+        let runtime_config = loader
+            .load()
+            .unwrap_or_else(|_| runtime::RuntimeConfig::empty());
+        println!(
+            "{}",
+            format_sandbox_report(&resolve_sandbox_status(runtime_config.sandbox(), &cwd))
+        );
+    }
+
     fn set_model(&mut self, model: Option<String>) -> Result<bool, Box<dyn std::error::Error>> {
         let Some(model) = model else {
             println!(
@@ -1536,6 +1566,7 @@ fn status_context(
     let project_context = ProjectContext::discover_with_git(&cwd, DEFAULT_DATE)?;
     let (project_root, git_branch) =
         parse_git_status_metadata(project_context.git_status.as_deref());
+    let sandbox_status = resolve_sandbox_status(runtime_config.sandbox(), &cwd);
     Ok(StatusContext {
         cwd,
         session_path: session_path.map(Path::to_path_buf),
@@ -1544,6 +1575,7 @@ fn status_context(
         memory_file_count: project_context.instruction_files.len(),
         project_root,
         git_branch,
+        sandbox_status,
     })
 }
 
@@ -1596,6 +1628,7 @@ fn format_status_report(
             context.discovered_config_files,
             context.memory_file_count,
         ),
+        format_sandbox_report(&context.sandbox_status),
     ]
     .join(
         "
@@ -1604,6 +1637,49 @@ fn format_status_report(
     )
 }
 
+fn format_sandbox_report(status: &runtime::SandboxStatus) -> String {
+    format!(
+        "Sandbox
+  Enabled           {}
+  Active            {}
+  Supported         {}
+  In container      {}
+  Requested ns      {}
+  Active ns         {}
+  Requested net     {}
+  Active net        {}
+  Filesystem mode   {}
+  Filesystem active {}
+  Allowed mounts    {}
+  Markers           {}
+  Fallback reason   {}",
+        status.enabled,
+        status.active,
+        status.supported,
+        status.in_container,
+        status.requested.namespace_restrictions,
+        status.namespace_active,
+        status.requested.network_isolation,
+        status.network_active,
+        status.filesystem_mode.as_str(),
+        status.filesystem_active,
+        if status.allowed_mounts.is_empty() {
+            "<none>".to_string()
+        } else {
+            status.allowed_mounts.join(", ")
+        },
+        if status.container_markers.is_empty() {
+            "<none>".to_string()
+        } else {
+            status.container_markers.join(", ")
+        },
+        status
+            .fallback_reason
+            .clone()
+            .unwrap_or_else(|| "<none>".to_string()),
+    )
+}
+
 fn render_config_report(section: Option<&str>) -> Result<String, Box<dyn std::error::Error>> {
     let cwd = env::current_dir()?;
     let loader = ConfigLoader::default_for(&cwd);
@@ -2020,7 +2096,7 @@ impl ApiClient for AnthropicRuntimeClient {
         let message_request = MessageRequest {
             model: self.model.clone(),
             max_tokens: DEFAULT_MAX_TOKENS,
-            messages: convert_messages(&request.messages)?,
+            messages: convert_messages(&request.messages),
             system: (!request.system_prompt.is_empty()).then(|| request.system_prompt.join("\n\n")),
             tools: self.enable_tools.then(|| {
                 filter_tool_specs(self.allowed_tools.as_ref())
@@ -2299,10 +2375,7 @@ fn tool_permission_specs() -> Vec<ToolSpec> {
     mvp_tool_specs()
 }
 
-fn convert_messages(messages: &[ConversationMessage]) -> Result<Vec<InputMessage>, RuntimeError> {
+fn convert_messages(messages: &[ConversationMessage]) -> Vec<InputMessage> {
-    let cwd = env::current_dir().map_err(|error| {
-        RuntimeError::new(format!("failed to resolve current directory: {error}"))
-    })?;
     messages
         .iter()
         .filter_map(|message| {
@@ -2313,224 +2386,36 @@ fn convert_messages(messages: &[ConversationMessage]) -> Result<Vec<InputMessage
             let content = message
                 .blocks
                 .iter()
-                .try_fold(Vec::new(), |mut acc, block| {
+                .map(|block| match block {
-                    match block {
+                    ContentBlock::Text { text } => InputContentBlock::Text { text: text.clone() },
-                        ContentBlock::Text { text } => {
+                    ContentBlock::ToolUse { id, name, input } => InputContentBlock::ToolUse {
-                            if message.role == MessageRole::User {
+                        id: id.clone(),
-                                acc.extend(
+                        name: name.clone(),
-                                    prompt_to_content_blocks(text, &cwd)
+                        input: serde_json::from_str(input)
-                                        .map_err(RuntimeError::new)?,
+                            .unwrap_or_else(|_| serde_json::json!({ "raw": input })),
-                                );
+                    },
-                            } else {
+                    ContentBlock::ToolResult {
-                                acc.push(InputContentBlock::Text { text: text.clone() });
+                        tool_use_id,
-                            }
+                        output,
-                        }
+                        is_error,
-                        ContentBlock::ToolUse { id, name, input } => {
+                        ..
-                            acc.push(InputContentBlock::ToolUse {
+                    } => InputContentBlock::ToolResult {
-                                id: id.clone(),
+                        tool_use_id: tool_use_id.clone(),
-                                name: name.clone(),
+                        content: vec![ToolResultContentBlock::Text {
-                                input: serde_json::from_str(input)
+                            text: output.clone(),
-                                    .unwrap_or_else(|_| serde_json::json!({ "raw": input })),
+                        }],
-                            });
+                        is_error: *is_error,
-                        }
+                    },
-                        ContentBlock::ToolResult {
+                })
-                            tool_use_id,
+                .collect::<Vec<_>>();
-                            output,
+            (!content.is_empty()).then(|| InputMessage {
-                            is_error,
+                role: role.to_string(),
-                            ..
+                content,
-                        } => acc.push(InputContentBlock::ToolResult {
+            })
-                            tool_use_id: tool_use_id.clone(),
-                            content: vec![ToolResultContentBlock::Text {
-                                text: output.clone(),
-                            }],
-                            is_error: *is_error,
-                        }),
-                    }
-                    Ok::<_, RuntimeError>(acc)
-                });
-            match content {
-                Ok(content) if !content.is_empty() => Some(Ok(InputMessage {
-                    role: role.to_string(),
-                    content,
-                })),
-                Ok(_) => None,
-                Err(error) => Some(Err(error)),
-            }
         })
         .collect()
 }
 
-fn prompt_to_content_blocks(input: &str, cwd: &Path) -> Result<Vec<InputContentBlock>, String> {
-    let mut blocks = Vec::new();
-    let mut text_buffer = String::new();
-    let mut chars = input.char_indices().peekable();
-
-    while let Some((index, ch)) = chars.next() {
-        if ch == '!' && input[index..].starts_with("![") {
-            if let Some((alt_end, path_start, path_end)) = parse_markdown_image_ref(input, index) {
-                let _ = alt_end;
-                flush_text_block(&mut blocks, &mut text_buffer);
-                let path = &input[path_start..path_end];
-                blocks.push(load_image_block(path, cwd)?);
-                while let Some((next_index, _)) = chars.peek() {
-                    if *next_index < path_end + 1 {
-                        let _ = chars.next();
-                    } else {
-                        break;
-                    }
-                }
-                continue;
-            }
-        }
-
-        if ch == '@' && is_ref_boundary(input[..index].chars().next_back()) {
-            let path_end = find_path_end(input, index + 1);
-            if path_end > index + 1 {
-                let candidate = &input[index + 1..path_end];
-                if looks_like_image_ref(candidate, cwd) {
-                    flush_text_block(&mut blocks, &mut text_buffer);
-                    blocks.push(load_image_block(candidate, cwd)?);
-                    while let Some((next_index, _)) = chars.peek() {
-                        if *next_index < path_end {
-                            let _ = chars.next();
-                        } else {
-                            break;
-                        }
-                    }
-                    continue;
-                }
-            }
-        }
-
-        text_buffer.push(ch);
-    }
-
-    flush_text_block(&mut blocks, &mut text_buffer);
-    if blocks.is_empty() {
-        blocks.push(InputContentBlock::Text {
-            text: input.to_string(),
-        });
-    }
-    Ok(blocks)
-}
-
-fn parse_markdown_image_ref(input: &str, start: usize) -> Option<(usize, usize, usize)> {
-    let after_bang = input.get(start + 2..)?;
-    let alt_end_offset = after_bang.find("](")?;
-    let path_start = start + 2 + alt_end_offset + 2;
-    let remainder = input.get(path_start..)?;
-    let path_end_offset = remainder.find(')')?;
-    let path_end = path_start + path_end_offset;
-    Some((start + 2 + alt_end_offset, path_start, path_end))
-}
-
-fn is_ref_boundary(ch: Option<char>) -> bool {
-    ch.is_none_or(char::is_whitespace)
-}
-
-fn find_path_end(input: &str, start: usize) -> usize {
-    input[start..]
-        .char_indices()
-        .find_map(|(offset, ch)| (ch.is_whitespace()).then_some(start + offset))
-        .unwrap_or(input.len())
-}
-
-fn looks_like_image_ref(candidate: &str, cwd: &Path) -> bool {
-    let resolved = resolve_prompt_path(candidate, cwd);
-    media_type_for_path(Path::new(candidate)).is_some()
-        || resolved.is_file()
-        || candidate.contains(std::path::MAIN_SEPARATOR)
-        || candidate.starts_with("./")
-        || candidate.starts_with("../")
-}
-
-fn flush_text_block(blocks: &mut Vec<InputContentBlock>, text_buffer: &mut String) {
-    if text_buffer.is_empty() {
-        return;
-    }
-    blocks.push(InputContentBlock::Text {
-        text: std::mem::take(text_buffer),
-    });
-}
-
-fn load_image_block(path_ref: &str, cwd: &Path) -> Result<InputContentBlock, String> {
-    let resolved = resolve_prompt_path(path_ref, cwd);
-    let media_type = media_type_for_path(&resolved).ok_or_else(|| {
-        format!(
-            "unsupported image format for reference {IMAGE_REF_PREFIX}{path_ref}; supported: png, jpg, jpeg, gif, webp"
-        )
-    })?;
-    let bytes = fs::read(&resolved).map_err(|error| {
-        format!(
-            "failed to read image reference {}: {error}",
-            resolved.display()
-        )
-    })?;
-    Ok(InputContentBlock::Image {
-        source: ImageSource {
-            kind: "base64".to_string(),
-            media_type: media_type.to_string(),
-            data: encode_base64(&bytes),
-        },
-    })
-}
-
-fn resolve_prompt_path(path_ref: &str, cwd: &Path) -> PathBuf {
-    let path = Path::new(path_ref);
-    if path.is_absolute() {
-        path.to_path_buf()
-    } else {
-        cwd.join(path)
-    }
-}
-
-fn media_type_for_path(path: &Path) -> Option<&'static str> {
-    let extension = path.extension()?.to_str()?.to_ascii_lowercase();
-    match extension.as_str() {
-        "png" => Some("image/png"),
-        "jpg" | "jpeg" => Some("image/jpeg"),
-        "gif" => Some("image/gif"),
-        "webp" => Some("image/webp"),
-        _ => None,
-    }
-}
-
-fn encode_base64(bytes: &[u8]) -> String {
-    const TABLE: &[u8; 64] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-    let mut output = String::new();
-    let mut index = 0;
-    while index + 3 <= bytes.len() {
-        let block = (u32::from(bytes[index]) << 16)
-            | (u32::from(bytes[index + 1]) << 8)
-            | u32::from(bytes[index + 2]);
-        output.push(TABLE[((block >> 18) & 0x3F) as usize] as char);
-        output.push(TABLE[((block >> 12) & 0x3F) as usize] as char);
-        output.push(TABLE[((block >> 6) & 0x3F) as usize] as char);
-        output.push(TABLE[(block & 0x3F) as usize] as char);
-        index += 3;
-    }
-
-    match bytes.len().saturating_sub(index) {
-        1 => {
-            let block = u32::from(bytes[index]) << 16;
-            output.push(TABLE[((block >> 18) & 0x3F) as usize] as char);
-            output.push(TABLE[((block >> 12) & 0x3F) as usize] as char);
-            output.push('=');
-            output.push('=');
-        }
-        2 => {
-            let block = (u32::from(bytes[index]) << 16) | (u32::from(bytes[index + 1]) << 8);
-            output.push(TABLE[((block >> 18) & 0x3F) as usize] as char);
-            output.push(TABLE[((block >> 12) & 0x3F) as usize] as char);
-            output.push(TABLE[((block >> 6) & 0x3F) as usize] as char);
-            output.push('=');
-        }
-        _ => {}
-    }
-
-    output
-}
-
 fn print_help() {
     println!("rusty-claude-cli v{VERSION}");
     println!();
@@ -2587,10 +2472,8 @@ mod tests {
         render_memory_report, render_repl_help, resume_supported_slash_commands, status_context,
         CliAction, CliOutputFormat, SlashCommand, StatusUsage, DEFAULT_MODEL,
     };
-    use api::InputContentBlock;
     use runtime::{ContentBlock, ConversationMessage, MessageRole, PermissionMode};
     use std::path::{Path, PathBuf};
-    use std::time::{SystemTime, UNIX_EPOCH};
 
     #[test]
     fn defaults_to_repl_when_no_args() {
@@ -2793,6 +2676,7 @@ mod tests {
         assert!(help.contains("REPL"));
         assert!(help.contains("/help"));
         assert!(help.contains("/status"));
+        assert!(help.contains("/sandbox"));
         assert!(help.contains("/model [model]"));
         assert!(help.contains("/permissions [read-only|workspace-write|danger-full-access]"));
         assert!(help.contains("/clear [--confirm]"));
@@ -2817,8 +2701,8 @@ mod tests {
         assert_eq!(
             names,
             vec![
-                "help", "status", "compact", "clear", "cost", "config", "memory", "init", "diff",
+                "help", "status", "sandbox", "compact", "clear", "cost", "config", "memory",
-                "version", "export",
+                "init", "diff", "version", "export",
             ]
         );
     }
@@ -2936,6 +2820,7 @@ mod tests {
                 memory_file_count: 4,
                 project_root: Some(PathBuf::from("/tmp")),
                 git_branch: Some("main".to_string()),
+                sandbox_status: runtime::SandboxStatus::default(),
             },
         );
         assert!(status.contains("Status"));
@@ -2989,7 +2874,7 @@ mod tests {
     fn status_context_reads_real_workspace_metadata() {
         let context = status_context(None).expect("status context should load");
         assert!(context.cwd.is_absolute());
-        assert!(context.discovered_config_files >= 3);
+        assert_eq!(context.discovered_config_files, 5);
         assert!(context.loaded_config_files <= context.discovered_config_files);
     }
 
@@ -3073,110 +2958,11 @@ mod tests {
             },
         ];
 
-        let converted = super::convert_messages(&messages).expect("messages should convert");
+        let converted = super::convert_messages(&messages);
         assert_eq!(converted.len(), 3);
         assert_eq!(converted[1].role, "assistant");
         assert_eq!(converted[2].role, "user");
     }
-
-    #[test]
-    fn prompt_to_content_blocks_keeps_text_only_prompt() {
-        let blocks = super::prompt_to_content_blocks("hello world", Path::new("."))
-            .expect("text prompt should parse");
-        assert_eq!(
-            blocks,
-            vec![InputContentBlock::Text {
-                text: "hello world".to_string()
-            }]
-        );
-    }
-
-    #[test]
-    fn prompt_to_content_blocks_embeds_at_image_refs() {
-        let temp = temp_fixture_dir("at-image-ref");
-        let image_path = temp.join("sample.png");
-        std::fs::write(&image_path, [1_u8, 2, 3]).expect("fixture write");
-        let prompt = format!("describe @{} please", image_path.display());
-
-        let blocks = super::prompt_to_content_blocks(&prompt, Path::new("."))
-            .expect("image ref should parse");
-
-        assert!(matches!(
-            &blocks[0],
-            InputContentBlock::Text { text } if text == "describe "
-        ));
-        assert!(matches!(
-            &blocks[1],
-            InputContentBlock::Image { source }
-                if source.kind == "base64"
-                    && source.media_type == "image/png"
-                    && source.data == "AQID"
-        ));
-        assert!(matches!(
-            &blocks[2],
-            InputContentBlock::Text { text } if text == " please"
-        ));
-    }
-
-    #[test]
-    fn prompt_to_content_blocks_embeds_markdown_image_refs() {
-        let temp = temp_fixture_dir("markdown-image-ref");
-        let image_path = temp.join("sample.webp");
-        std::fs::write(&image_path, [255_u8]).expect("fixture write");
-        let prompt = format!("see ![asset]({}) now", image_path.display());
-
-        let blocks = super::prompt_to_content_blocks(&prompt, Path::new("."))
-            .expect("markdown image ref should parse");
-
-        assert!(matches!(
-            &blocks[1],
-            InputContentBlock::Image { source }
-                if source.media_type == "image/webp" && source.data == "/w=="
-        ));
-    }
-
-    #[test]
-    fn prompt_to_content_blocks_rejects_unsupported_formats() {
-        let temp = temp_fixture_dir("unsupported-image-ref");
-        let image_path = temp.join("sample.bmp");
-        std::fs::write(&image_path, [1_u8]).expect("fixture write");
-        let prompt = format!("describe @{}", image_path.display());
-
-        let error = super::prompt_to_content_blocks(&prompt, Path::new("."))
-            .expect_err("unsupported image ref should fail");
-
-        assert!(error.contains("unsupported image format"));
-    }
-
-    #[test]
-    fn convert_messages_expands_user_text_image_refs() {
-        let temp = temp_fixture_dir("convert-message-image-ref");
-        let image_path = temp.join("sample.gif");
-        std::fs::write(&image_path, [71_u8, 73, 70]).expect("fixture write");
-        let messages = vec![ConversationMessage::user_text(format!(
-            "inspect @{}",
-            image_path.display()
-        ))];
-
-        let converted = super::convert_messages(&messages).expect("messages should convert");
-
-        assert_eq!(converted.len(), 1);
-        assert!(matches!(
-            &converted[0].content[1],
-            InputContentBlock::Image { source }
-                if source.media_type == "image/gif" && source.data == "R0lG"
-        ));
-    }
-
-    fn temp_fixture_dir(label: &str) -> PathBuf {
-        let unique = SystemTime::now()
-            .duration_since(UNIX_EPOCH)
-            .expect("clock should advance")
-            .as_nanos();
-        let path = std::env::temp_dir().join(format!("rusty-claude-cli-{label}-{unique}"));
-        std::fs::create_dir_all(&path).expect("temp dir should exist");
-        path
-    }
     #[test]
     fn repl_help_mentions_history_completion_and_multiline() {
         let help = render_repl_help();
@@ -3196,3 +2982,17 @@ mod tests {
         assert!(done.contains("contents"));
     }
 }
+
+#[cfg(test)]
+mod sandbox_report_tests {
+    use super::format_sandbox_report;
+
+    #[test]
+    fn sandbox_report_renders_expected_fields() {
+        let report = format_sandbox_report(&runtime::SandboxStatus::default());
+        assert!(report.contains("Sandbox"));
+        assert!(report.contains("Enabled"));
+        assert!(report.contains("Filesystem mode"));
+        assert!(report.contains("Fallback reason"));
+    }
+}

rust/crates/tools/src/lib.rs

@@ -62,7 +62,11 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                     "timeout": { "type": "integer", "minimum": 1 },
                     "description": { "type": "string" },
                     "run_in_background": { "type": "boolean" },
-                    "dangerouslyDisableSandbox": { "type": "boolean" }
+                    "dangerouslyDisableSandbox": { "type": "boolean" },
+                    "namespaceRestrictions": { "type": "boolean" },
+                    "isolateNetwork": { "type": "boolean" },
+                    "filesystemMode": { "type": "string", "enum": ["off", "workspace-only", "allow-list"] },
+                    "allowedMounts": { "type": "array", "items": { "type": "string" } }
                 },
                 "required": ["command"],
                 "additionalProperties": false
@@ -2214,6 +2218,7 @@ fn execute_shell_command(
             structured_content: None,
             persisted_output_path: None,
             persisted_output_size: None,
+            sandbox_status: None,
         });
     }
 
@@ -2251,6 +2256,7 @@ fn execute_shell_command(
                     structured_content: None,
                     persisted_output_path: None,
                     persisted_output_size: None,
+                    sandbox_status: None,
                 });
             }
             if started.elapsed() >= Duration::from_millis(timeout_ms) {
@@ -2281,6 +2287,7 @@ Command exceeded timeout of {timeout_ms} ms",
                     structured_content: None,
                     persisted_output_path: None,
                     persisted_output_size: None,
+                    sandbox_status: None,
                 });
             }
             std::thread::sleep(Duration::from_millis(10));
@@ -2307,6 +2314,7 @@ Command exceeded timeout of {timeout_ms} ms",
         structured_content: None,
         persisted_output_path: None,
         persisted_output_size: None,
+        sandbox_status: None,
     })
 }