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/README.md

@@ -102,6 +102,13 @@ cd rust
 cargo run -p rusty-claude-cli -- --model claude-sonnet-4-20250514 prompt "List the key crates in this workspace"
 ```
 
+Restrict enabled tools in an interactive session:
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli -- --allowedTools read,glob
+```
+
 ### 2) REPL mode
 
 Start the interactive shell:
@@ -123,6 +130,10 @@ Inside the REPL, useful commands include:
 /memory
 /config
 /init
+/diff
+/version
+/export notes.txt
+/session list
 /exit
 ```
 
@@ -169,6 +180,10 @@ cargo run -p rusty-claude-cli -- --resume session.json /memory /config
 - `/config [env|hooks|model]` — inspect discovered Claude config
 - `/memory` — inspect loaded instruction memory files
 - `/init` — create a starter `CLAUDE.md`
+- `/diff` — show the current git diff for the workspace
+- `/version` — print version and build metadata locally
+- `/export [file]` — export the current conversation transcript
+- `/session [list|switch <session-id>]` — inspect or switch managed local sessions
 - `/exit` — leave the REPL
 
 ## Environment variables

rust/crates/api/src/client.rs

@@ -392,8 +392,52 @@ pub fn resolve_saved_oauth_token(config: &OAuthConfig) -> Result<Option<OAuthTok
     let Some(token_set) = load_saved_oauth_token()? else {
         return Ok(None);
     };
+    resolve_saved_oauth_token_set(config, token_set).map(Some)
+}
+
+pub fn resolve_startup_auth_source<F>(load_oauth_config: F) -> Result<AuthSource, ApiError>
+where
+    F: FnOnce() -> Result<Option<OAuthConfig>, ApiError>,
+{
+    if let Some(api_key) = read_env_non_empty("ANTHROPIC_API_KEY")? {
+        return match read_env_non_empty("ANTHROPIC_AUTH_TOKEN")? {
+            Some(bearer_token) => Ok(AuthSource::ApiKeyAndBearer {
+                api_key,
+                bearer_token,
+            }),
+            None => Ok(AuthSource::ApiKey(api_key)),
+        };
+    }
+    if let Some(bearer_token) = read_env_non_empty("ANTHROPIC_AUTH_TOKEN")? {
+        return Ok(AuthSource::BearerToken(bearer_token));
+    }
+
+    let Some(token_set) = load_saved_oauth_token()? else {
+        return Err(ApiError::MissingApiKey);
+    };
     if !oauth_token_is_expired(&token_set) {
-        return Ok(Some(token_set));
+        return Ok(AuthSource::BearerToken(token_set.access_token));
+    }
+    if token_set.refresh_token.is_none() {
+        return Err(ApiError::ExpiredOAuthToken);
+    }
+
+    let Some(config) = load_oauth_config()? else {
+        return Err(ApiError::Auth(
+            "saved OAuth token is expired; runtime OAuth config is missing".to_string(),
+        ));
+    };
+    Ok(AuthSource::from(resolve_saved_oauth_token_set(
+        &config, token_set,
+    )?))
+}
+
+fn resolve_saved_oauth_token_set(
+    config: &OAuthConfig,
+    token_set: OAuthTokenSet,
+) -> Result<OAuthTokenSet, ApiError> {
+    if !oauth_token_is_expired(&token_set) {
+        return Ok(token_set);
     }
     let Some(refresh_token) = token_set.refresh_token.clone() else {
         return Err(ApiError::ExpiredOAuthToken);
@@ -403,18 +447,28 @@ pub fn resolve_saved_oauth_token(config: &OAuthConfig) -> Result<Option<OAuthTok
         client
             .refresh_oauth_token(
                 config,
-                &OAuthRefreshRequest::from_config(config, refresh_token, Some(token_set.scopes)),
+                &OAuthRefreshRequest::from_config(
+                    config,
+                    refresh_token,
+                    Some(token_set.scopes.clone()),
+                ),
             )
             .await
     })?;
-    save_oauth_credentials(&runtime::OAuthTokenSet {
-        access_token: refreshed.access_token.clone(),
-        refresh_token: refreshed.refresh_token.clone(),
+    let resolved = OAuthTokenSet {
+        access_token: refreshed.access_token,
+        refresh_token: refreshed.refresh_token.or(token_set.refresh_token),
         expires_at: refreshed.expires_at,
-        scopes: refreshed.scopes.clone(),
+        scopes: refreshed.scopes,
+    };
+    save_oauth_credentials(&runtime::OAuthTokenSet {
+        access_token: resolved.access_token.clone(),
+        refresh_token: resolved.refresh_token.clone(),
+        expires_at: resolved.expires_at,
+        scopes: resolved.scopes.clone(),
     })
     .map_err(ApiError::from)?;
-    Ok(Some(refreshed))
+    Ok(resolved)
 }
 
 fn client_runtime_block_on<F, T>(future: F) -> Result<T, ApiError>
@@ -571,8 +625,8 @@ mod tests {
     use runtime::{clear_oauth_credentials, save_oauth_credentials, OAuthConfig};
 
     use crate::client::{
-        now_unix_timestamp, oauth_token_is_expired, resolve_saved_oauth_token, AnthropicClient,
-        AuthSource, OAuthTokenSet,
+        now_unix_timestamp, oauth_token_is_expired, resolve_saved_oauth_token,
+        resolve_startup_auth_source, AnthropicClient, AuthSource, OAuthTokenSet,
     };
     use crate::types::{ContentBlockDelta, MessageRequest};
 
@@ -760,6 +814,95 @@ mod tests {
         std::fs::remove_dir_all(config_home).expect("cleanup temp dir");
     }
 
+    #[test]
+    fn resolve_startup_auth_source_uses_saved_oauth_without_loading_config() {
+        let _guard = env_lock();
+        let config_home = temp_config_home();
+        std::env::set_var("CLAUDE_CONFIG_HOME", &config_home);
+        std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
+        std::env::remove_var("ANTHROPIC_API_KEY");
+        save_oauth_credentials(&runtime::OAuthTokenSet {
+            access_token: "saved-access-token".to_string(),
+            refresh_token: Some("refresh".to_string()),
+            expires_at: Some(now_unix_timestamp() + 300),
+            scopes: vec!["scope:a".to_string()],
+        })
+        .expect("save oauth credentials");
+
+        let auth = resolve_startup_auth_source(|| panic!("config should not be loaded"))
+            .expect("startup auth");
+        assert_eq!(auth.bearer_token(), Some("saved-access-token"));
+
+        clear_oauth_credentials().expect("clear credentials");
+        std::env::remove_var("CLAUDE_CONFIG_HOME");
+        std::fs::remove_dir_all(config_home).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn resolve_startup_auth_source_errors_when_refreshable_token_lacks_config() {
+        let _guard = env_lock();
+        let config_home = temp_config_home();
+        std::env::set_var("CLAUDE_CONFIG_HOME", &config_home);
+        std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
+        std::env::remove_var("ANTHROPIC_API_KEY");
+        save_oauth_credentials(&runtime::OAuthTokenSet {
+            access_token: "expired-access-token".to_string(),
+            refresh_token: Some("refresh-token".to_string()),
+            expires_at: Some(1),
+            scopes: vec!["scope:a".to_string()],
+        })
+        .expect("save expired oauth credentials");
+
+        let error =
+            resolve_startup_auth_source(|| Ok(None)).expect_err("missing config should error");
+        assert!(
+            matches!(error, crate::error::ApiError::Auth(message) if message.contains("runtime OAuth config is missing"))
+        );
+
+        let stored = runtime::load_oauth_credentials()
+            .expect("load stored credentials")
+            .expect("stored token set");
+        assert_eq!(stored.access_token, "expired-access-token");
+        assert_eq!(stored.refresh_token.as_deref(), Some("refresh-token"));
+
+        clear_oauth_credentials().expect("clear credentials");
+        std::env::remove_var("CLAUDE_CONFIG_HOME");
+        std::fs::remove_dir_all(config_home).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn resolve_saved_oauth_token_preserves_refresh_token_when_refresh_response_omits_it() {
+        let _guard = env_lock();
+        let config_home = temp_config_home();
+        std::env::set_var("CLAUDE_CONFIG_HOME", &config_home);
+        std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
+        std::env::remove_var("ANTHROPIC_API_KEY");
+        save_oauth_credentials(&runtime::OAuthTokenSet {
+            access_token: "expired-access-token".to_string(),
+            refresh_token: Some("refresh-token".to_string()),
+            expires_at: Some(1),
+            scopes: vec!["scope:a".to_string()],
+        })
+        .expect("save expired oauth credentials");
+
+        let token_url = spawn_token_server(
+            "{\"access_token\":\"refreshed-token\",\"expires_at\":9999999999,\"scopes\":[\"scope:a\"]}",
+        );
+        let resolved = resolve_saved_oauth_token(&sample_oauth_config(token_url))
+            .expect("resolve refreshed token")
+            .expect("token set present");
+        assert_eq!(resolved.access_token, "refreshed-token");
+        assert_eq!(resolved.refresh_token.as_deref(), Some("refresh-token"));
+        let stored = runtime::load_oauth_credentials()
+            .expect("load stored credentials")
+            .expect("stored token set");
+        assert_eq!(stored.refresh_token.as_deref(), Some("refresh-token"));
+
+        clear_oauth_credentials().expect("clear credentials");
+        std::env::remove_var("CLAUDE_CONFIG_HOME");
+        std::fs::remove_dir_all(config_home).expect("cleanup temp dir");
+    }
+
     #[test]
     fn message_request_stream_helper_sets_stream_true() {
         let request = MessageRequest {

rust/crates/api/src/lib.rs

@@ -4,8 +4,8 @@ mod sse;
 mod types;
 
 pub use client::{
-    oauth_token_is_expired, resolve_saved_oauth_token, AnthropicClient, AuthSource, MessageStream,
-    OAuthTokenSet,
+    oauth_token_is_expired, resolve_saved_oauth_token, resolve_startup_auth_source,
+    AnthropicClient, AuthSource, MessageStream, OAuthTokenSet,
 };
 pub use error::ApiError;
 pub use sse::{parse_frame, SseParser};

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!(resume_supported_slash_commands().len(), 11);
+        assert_eq!(slash_command_specs().len(), 16);
+        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")
-            .arg("-lc")
-            .arg(&input.command)
+        let mut child = prepare_command(&input.command, &cwd, &sandbox_status, false);
+        let child = child
             .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> {
-    let mut command = TokioCommand::new("sh");
-    command.arg("-lc").arg(&input.command);
+async fn execute_bash_async(
+    input: BashCommandInput,
+    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";
 
@@ -14,6 +15,13 @@ pub enum ConfigSource {
     Local,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ResolvedPermissionMode {
+    ReadOnly,
+    WorkspaceWrite,
+    DangerFullAccess,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct ConfigEntry {
     pub source: ConfigSource,
@@ -31,6 +39,9 @@ pub struct RuntimeConfig {
 pub struct RuntimeFeatureConfig {
     mcp: McpConfigCollection,
     oauth: Option<OAuthConfig>,
+    model: Option<String>,
+    permission_mode: Option<ResolvedPermissionMode>,
+    sandbox: SandboxConfig,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
@@ -165,11 +176,23 @@ impl ConfigLoader {
 
     #[must_use]
     pub fn discover(&self) -> Vec<ConfigEntry> {
+        let user_legacy_path = self.config_home.parent().map_or_else(
+            || PathBuf::from(".claude.json"),
+            |parent| parent.join(".claude.json"),
+        );
         vec![
+            ConfigEntry {
+                source: ConfigSource::User,
+                path: user_legacy_path,
+            },
             ConfigEntry {
                 source: ConfigSource::User,
                 path: self.config_home.join("settings.json"),
             },
+            ConfigEntry {
+                source: ConfigSource::Project,
+                path: self.cwd.join(".claude.json"),
+            },
             ConfigEntry {
                 source: ConfigSource::Project,
                 path: self.cwd.join(".claude").join("settings.json"),
@@ -195,14 +218,16 @@ impl ConfigLoader {
             loaded_entries.push(entry);
         }
 
+        let merged_value = JsonValue::Object(merged.clone());
+
         let feature_config = RuntimeFeatureConfig {
             mcp: McpConfigCollection {
                 servers: mcp_servers,
             },
-            oauth: parse_optional_oauth_config(
-                &JsonValue::Object(merged.clone()),
-                "merged settings.oauth",
-            )?,
+            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 {
@@ -257,6 +282,21 @@ impl RuntimeConfig {
     pub fn oauth(&self) -> Option<&OAuthConfig> {
         self.feature_config.oauth.as_ref()
     }
+
+    #[must_use]
+    pub fn model(&self) -> Option<&str> {
+        self.feature_config.model.as_deref()
+    }
+
+    #[must_use]
+    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 {
@@ -269,6 +309,21 @@ impl RuntimeFeatureConfig {
     pub fn oauth(&self) -> Option<&OAuthConfig> {
         self.oauth.as_ref()
     }
+
+    #[must_use]
+    pub fn model(&self) -> Option<&str> {
+        self.model.as_deref()
+    }
+
+    #[must_use]
+    pub fn permission_mode(&self) -> Option<ResolvedPermissionMode> {
+        self.permission_mode
+    }
+
+    #[must_use]
+    pub fn sandbox(&self) -> &SandboxConfig {
+        &self.sandbox
+    }
 }
 
 impl McpConfigCollection {
@@ -307,6 +362,7 @@ impl McpServerConfig {
 fn read_optional_json_object(
     path: &Path,
 ) -> Result<Option<BTreeMap<String, JsonValue>>, ConfigError> {
+    let is_legacy_config = path.file_name().and_then(|name| name.to_str()) == Some(".claude.json");
     let contents = match fs::read_to_string(path) {
         Ok(contents) => contents,
         Err(error) if error.kind() == std::io::ErrorKind::NotFound => return Ok(None),
@@ -317,14 +373,20 @@ fn read_optional_json_object(
         return Ok(Some(BTreeMap::new()));
     }
 
-    let parsed = JsonValue::parse(&contents)
-        .map_err(|error| ConfigError::Parse(format!("{}: {error}", path.display())))?;
-    let object = parsed.as_object().ok_or_else(|| {
-        ConfigError::Parse(format!(
+    let parsed = match JsonValue::parse(&contents) {
+        Ok(parsed) => parsed,
+        Err(error) if is_legacy_config => return Ok(None),
+        Err(error) => return Err(ConfigError::Parse(format!("{}: {error}", path.display()))),
+    };
+    let Some(object) = parsed.as_object() else {
+        if is_legacy_config {
+            return Ok(None);
+        }
+        return Err(ConfigError::Parse(format!(
             "{}: top-level settings value must be a JSON object",
             path.display()
-        ))
-    })?;
+        )));
+    };
     Ok(Some(object.clone()))
 }
 
@@ -355,6 +417,83 @@ fn merge_mcp_servers(
     Ok(())
 }
 
+fn parse_optional_model(root: &JsonValue) -> Option<String> {
+    root.as_object()
+        .and_then(|object| object.get("model"))
+        .and_then(JsonValue::as_str)
+        .map(ToOwned::to_owned)
+}
+
+fn parse_optional_permission_mode(
+    root: &JsonValue,
+) -> Result<Option<ResolvedPermissionMode>, ConfigError> {
+    let Some(object) = root.as_object() else {
+        return Ok(None);
+    };
+    if let Some(mode) = object.get("permissionMode").and_then(JsonValue::as_str) {
+        return parse_permission_mode_label(mode, "merged settings.permissionMode").map(Some);
+    }
+    let Some(mode) = object
+        .get("permissions")
+        .and_then(JsonValue::as_object)
+        .and_then(|permissions| permissions.get("defaultMode"))
+        .and_then(JsonValue::as_str)
+    else {
+        return Ok(None);
+    };
+    parse_permission_mode_label(mode, "merged settings.permissions.defaultMode").map(Some)
+}
+
+fn parse_permission_mode_label(
+    mode: &str,
+    context: &str,
+) -> Result<ResolvedPermissionMode, ConfigError> {
+    match mode {
+        "default" | "plan" | "read-only" => Ok(ResolvedPermissionMode::ReadOnly),
+        "acceptEdits" | "auto" | "workspace-write" => Ok(ResolvedPermissionMode::WorkspaceWrite),
+        "dontAsk" | "danger-full-access" => Ok(ResolvedPermissionMode::DangerFullAccess),
+        other => Err(ConfigError::Parse(format!(
+            "{context}: unsupported permission mode {other}"
+        ))),
+    }
+}
+
+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,
@@ -594,9 +733,11 @@ fn deep_merge_objects(
 #[cfg(test)]
 mod tests {
     use super::{
-        ConfigLoader, ConfigSource, McpServerConfig, McpTransport, CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
+        ConfigLoader, ConfigSource, McpServerConfig, McpTransport, ResolvedPermissionMode,
+        CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
     };
     use crate::json::JsonValue;
+    use crate::sandbox::FilesystemIsolationMode;
     use std::fs;
     use std::time::{SystemTime, UNIX_EPOCH};
 
@@ -635,14 +776,24 @@ mod tests {
         fs::create_dir_all(cwd.join(".claude")).expect("project config dir");
         fs::create_dir_all(&home).expect("home config dir");
 
+        fs::write(
+            home.parent().expect("home parent").join(".claude.json"),
+            r#"{"model":"haiku","env":{"A":"1"},"mcpServers":{"home":{"command":"uvx","args":["home"]}}}"#,
+        )
+        .expect("write user compat config");
         fs::write(
             home.join("settings.json"),
-            r#"{"model":"sonnet","env":{"A":"1"},"hooks":{"PreToolUse":["base"]}}"#,
+            r#"{"model":"sonnet","env":{"A2":"1"},"hooks":{"PreToolUse":["base"]},"permissions":{"defaultMode":"plan"}}"#,
         )
         .expect("write user settings");
+        fs::write(
+            cwd.join(".claude.json"),
+            r#"{"model":"project-compat","env":{"B":"2"}}"#,
+        )
+        .expect("write project compat config");
         fs::write(
             cwd.join(".claude").join("settings.json"),
-            r#"{"env":{"B":"2"},"hooks":{"PostToolUse":["project"]}}"#,
+            r#"{"env":{"C":"3"},"hooks":{"PostToolUse":["project"]},"mcpServers":{"project":{"command":"uvx","args":["project"]}}}"#,
         )
         .expect("write project settings");
         fs::write(
@@ -656,25 +807,75 @@ mod tests {
             .expect("config should load");
 
         assert_eq!(CLAUDE_CODE_SETTINGS_SCHEMA_NAME, "SettingsSchema");
-        assert_eq!(loaded.loaded_entries().len(), 3);
+        assert_eq!(loaded.loaded_entries().len(), 5);
         assert_eq!(loaded.loaded_entries()[0].source, ConfigSource::User);
         assert_eq!(
             loaded.get("model"),
             Some(&JsonValue::String("opus".to_string()))
         );
+        assert_eq!(loaded.model(), Some("opus"));
+        assert_eq!(
+            loaded.permission_mode(),
+            Some(ResolvedPermissionMode::WorkspaceWrite)
+        );
         assert_eq!(
             loaded
                 .get("env")
                 .and_then(JsonValue::as_object)
                 .expect("env object")
                 .len(),
-            2
+            4
         );
         assert!(loaded
             .get("hooks")
             .and_then(JsonValue::as_object)
             .expect("hooks object")
             .contains_key("PreToolUse"));
+        assert!(loaded
+            .get("hooks")
+            .and_then(JsonValue::as_object)
+            .expect("hooks object")
+            .contains_key("PostToolUse"));
+        assert!(loaded.mcp().get("home").is_some());
+        assert!(loaded.mcp().get("project").is_some());
+
+        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");
     }

rust/crates/runtime/src/conversation.rs

@@ -408,7 +408,7 @@ mod tests {
                 .sum::<i32>();
             Ok(total.to_string())
         });
-        let permission_policy = PermissionPolicy::new(PermissionMode::Prompt);
+        let permission_policy = PermissionPolicy::new(PermissionMode::WorkspaceWrite);
         let system_prompt = SystemPromptBuilder::new()
             .with_project_context(ProjectContext {
                 cwd: PathBuf::from("/tmp/project"),
@@ -487,7 +487,7 @@ mod tests {
             Session::new(),
             SingleCallApiClient,
             StaticToolExecutor::new(),
-            PermissionPolicy::new(PermissionMode::Prompt),
+            PermissionPolicy::new(PermissionMode::WorkspaceWrite),
             vec!["system".to_string()],
         );
 
@@ -536,7 +536,7 @@ mod tests {
             session,
             SimpleApi,
             StaticToolExecutor::new(),
-            PermissionPolicy::new(PermissionMode::Allow),
+            PermissionPolicy::new(PermissionMode::DangerFullAccess),
             vec!["system".to_string()],
         );
 
@@ -563,7 +563,7 @@ mod tests {
             Session::new(),
             SimpleApi,
             StaticToolExecutor::new(),
-            PermissionPolicy::new(PermissionMode::Allow),
+            PermissionPolicy::new(PermissionMode::DangerFullAccess),
             vec!["system".to_string()],
         );
         runtime.run_turn("a", None).expect("turn a");

rust/crates/runtime/src/lib.rs

@@ -12,6 +12,7 @@ mod oauth;
 mod permissions;
 mod prompt;
 mod remote;
+mod sandbox;
 mod session;
 mod usage;
 
@@ -25,7 +26,8 @@ pub use config::{
     ConfigEntry, ConfigError, ConfigLoader, ConfigSource, McpClaudeAiProxyServerConfig,
     McpConfigCollection, McpOAuthConfig, McpRemoteServerConfig, McpSdkServerConfig,
     McpServerConfig, McpStdioServerConfig, McpTransport, McpWebSocketServerConfig, OAuthConfig,
-    RuntimeConfig, RuntimeFeatureConfig, ScopedMcpServerConfig, CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
+    ResolvedPermissionMode, RuntimeConfig, RuntimeFeatureConfig, ScopedMcpServerConfig,
+    CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
 };
 pub use conversation::{
     ApiClient, ApiRequest, AssistantEvent, ConversationRuntime, RuntimeError, StaticToolExecutor,
@@ -72,7 +74,21 @@ 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,
 };
+
+#[cfg(test)]
+pub(crate) fn test_env_lock() -> std::sync::MutexGuard<'static, ()> {
+    static LOCK: std::sync::OnceLock<std::sync::Mutex<()>> = std::sync::OnceLock::new();
+    LOCK.get_or_init(|| std::sync::Mutex::new(()))
+        .lock()
+        .unwrap_or_else(std::sync::PoisonError::into_inner)
+}

rust/crates/runtime/src/oauth.rs

@@ -448,7 +448,6 @@ fn decode_hex(byte: u8) -> Result<u8, String> {
 
 #[cfg(test)]
 mod tests {
-    use std::sync::{Mutex, OnceLock};
     use std::time::{SystemTime, UNIX_EPOCH};
 
     use super::{
@@ -470,10 +469,7 @@ mod tests {
     }
 
     fn env_lock() -> std::sync::MutexGuard<'static, ()> {
-        static LOCK: OnceLock<Mutex<()>> = OnceLock::new();
-        LOCK.get_or_init(|| Mutex::new(()))
-            .lock()
-            .expect("env lock")
+        crate::test_env_lock()
     }
 
     fn temp_config_home() -> std::path::PathBuf {

rust/crates/runtime/src/permissions.rs

@@ -1,16 +1,33 @@
 use std::collections::BTreeMap;
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub enum PermissionMode {
-    Allow,
-    Deny,
+    ReadOnly,
+    WorkspaceWrite,
+    DangerFullAccess,
     Prompt,
+    Allow,
+}
+
+impl PermissionMode {
+    #[must_use]
+    pub fn as_str(self) -> &'static str {
+        match self {
+            Self::ReadOnly => "read-only",
+            Self::WorkspaceWrite => "workspace-write",
+            Self::DangerFullAccess => "danger-full-access",
+            Self::Prompt => "prompt",
+            Self::Allow => "allow",
+        }
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct PermissionRequest {
     pub tool_name: String,
     pub input: String,
+    pub current_mode: PermissionMode,
+    pub required_mode: PermissionMode,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -31,31 +48,41 @@ pub enum PermissionOutcome {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct PermissionPolicy {
-    default_mode: PermissionMode,
-    tool_modes: BTreeMap<String, PermissionMode>,
+    active_mode: PermissionMode,
+    tool_requirements: BTreeMap<String, PermissionMode>,
 }
 
 impl PermissionPolicy {
     #[must_use]
-    pub fn new(default_mode: PermissionMode) -> Self {
+    pub fn new(active_mode: PermissionMode) -> Self {
         Self {
-            default_mode,
-            tool_modes: BTreeMap::new(),
+            active_mode,
+            tool_requirements: BTreeMap::new(),
         }
     }
 
     #[must_use]
-    pub fn with_tool_mode(mut self, tool_name: impl Into<String>, mode: PermissionMode) -> Self {
-        self.tool_modes.insert(tool_name.into(), mode);
+    pub fn with_tool_requirement(
+        mut self,
+        tool_name: impl Into<String>,
+        required_mode: PermissionMode,
+    ) -> Self {
+        self.tool_requirements
+            .insert(tool_name.into(), required_mode);
         self
     }
 
     #[must_use]
-    pub fn mode_for(&self, tool_name: &str) -> PermissionMode {
-        self.tool_modes
+    pub fn active_mode(&self) -> PermissionMode {
+        self.active_mode
+    }
+
+    #[must_use]
+    pub fn required_mode_for(&self, tool_name: &str) -> PermissionMode {
+        self.tool_requirements
             .get(tool_name)
             .copied()
-            .unwrap_or(self.default_mode)
+            .unwrap_or(PermissionMode::DangerFullAccess)
     }
 
     #[must_use]
@@ -65,23 +92,44 @@ impl PermissionPolicy {
         input: &str,
         mut prompter: Option<&mut dyn PermissionPrompter>,
     ) -> PermissionOutcome {
-        match self.mode_for(tool_name) {
-            PermissionMode::Allow => PermissionOutcome::Allow,
-            PermissionMode::Deny => PermissionOutcome::Deny {
-                reason: format!("tool '{tool_name}' denied by permission policy"),
-            },
-            PermissionMode::Prompt => match prompter.as_mut() {
-                Some(prompter) => match prompter.decide(&PermissionRequest {
-                    tool_name: tool_name.to_string(),
-                    input: input.to_string(),
-                }) {
+        let current_mode = self.active_mode();
+        let required_mode = self.required_mode_for(tool_name);
+        if current_mode == PermissionMode::Allow || current_mode >= required_mode {
+            return PermissionOutcome::Allow;
+        }
+
+        let request = PermissionRequest {
+            tool_name: tool_name.to_string(),
+            input: input.to_string(),
+            current_mode,
+            required_mode,
+        };
+
+        if current_mode == PermissionMode::Prompt
+            || (current_mode == PermissionMode::WorkspaceWrite
+                && required_mode == PermissionMode::DangerFullAccess)
+        {
+            return match prompter.as_mut() {
+                Some(prompter) => match prompter.decide(&request) {
                     PermissionPromptDecision::Allow => PermissionOutcome::Allow,
                     PermissionPromptDecision::Deny { reason } => PermissionOutcome::Deny { reason },
                 },
                 None => PermissionOutcome::Deny {
-                    reason: format!("tool '{tool_name}' requires interactive approval"),
+                    reason: format!(
+                        "tool '{tool_name}' requires approval to escalate from {} to {}",
+                        current_mode.as_str(),
+                        required_mode.as_str()
+                    ),
                 },
-            },
+            };
+        }
+
+        PermissionOutcome::Deny {
+            reason: format!(
+                "tool '{tool_name}' requires {} permission; current mode is {}",
+                required_mode.as_str(),
+                current_mode.as_str()
+            ),
         }
     }
 }
@@ -93,25 +141,92 @@ mod tests {
         PermissionPrompter, PermissionRequest,
     };
 
-    struct AllowPrompter;
+    struct RecordingPrompter {
+        seen: Vec<PermissionRequest>,
+        allow: bool,
+    }
 
-    impl PermissionPrompter for AllowPrompter {
+    impl PermissionPrompter for RecordingPrompter {
         fn decide(&mut self, request: &PermissionRequest) -> PermissionPromptDecision {
-            assert_eq!(request.tool_name, "bash");
-            PermissionPromptDecision::Allow
+            self.seen.push(request.clone());
+            if self.allow {
+                PermissionPromptDecision::Allow
+            } else {
+                PermissionPromptDecision::Deny {
+                    reason: "not now".to_string(),
+                }
+            }
         }
     }
 
     #[test]
-    fn uses_tool_specific_overrides() {
-        let policy = PermissionPolicy::new(PermissionMode::Deny)
-            .with_tool_mode("bash", PermissionMode::Prompt);
+    fn allows_tools_when_active_mode_meets_requirement() {
+        let policy = PermissionPolicy::new(PermissionMode::WorkspaceWrite)
+            .with_tool_requirement("read_file", PermissionMode::ReadOnly)
+            .with_tool_requirement("write_file", PermissionMode::WorkspaceWrite);
+
+        assert_eq!(
+            policy.authorize("read_file", "{}", None),
+            PermissionOutcome::Allow
+        );
+        assert_eq!(
+            policy.authorize("write_file", "{}", None),
+            PermissionOutcome::Allow
+        );
+    }
+
+    #[test]
+    fn denies_read_only_escalations_without_prompt() {
+        let policy = PermissionPolicy::new(PermissionMode::ReadOnly)
+            .with_tool_requirement("write_file", PermissionMode::WorkspaceWrite)
+            .with_tool_requirement("bash", PermissionMode::DangerFullAccess);
 
-        let outcome = policy.authorize("bash", "echo hi", Some(&mut AllowPrompter));
-        assert_eq!(outcome, PermissionOutcome::Allow);
         assert!(matches!(
-            policy.authorize("edit", "x", None),
-            PermissionOutcome::Deny { .. }
+            policy.authorize("write_file", "{}", None),
+            PermissionOutcome::Deny { reason } if reason.contains("requires workspace-write permission")
+        ));
+        assert!(matches!(
+            policy.authorize("bash", "{}", None),
+            PermissionOutcome::Deny { reason } if reason.contains("requires danger-full-access permission")
+        ));
+    }
+
+    #[test]
+    fn prompts_for_workspace_write_to_danger_full_access_escalation() {
+        let policy = PermissionPolicy::new(PermissionMode::WorkspaceWrite)
+            .with_tool_requirement("bash", PermissionMode::DangerFullAccess);
+        let mut prompter = RecordingPrompter {
+            seen: Vec::new(),
+            allow: true,
+        };
+
+        let outcome = policy.authorize("bash", "echo hi", Some(&mut prompter));
+
+        assert_eq!(outcome, PermissionOutcome::Allow);
+        assert_eq!(prompter.seen.len(), 1);
+        assert_eq!(prompter.seen[0].tool_name, "bash");
+        assert_eq!(
+            prompter.seen[0].current_mode,
+            PermissionMode::WorkspaceWrite
+        );
+        assert_eq!(
+            prompter.seen[0].required_mode,
+            PermissionMode::DangerFullAccess
+        );
+    }
+
+    #[test]
+    fn honors_prompt_rejection_reason() {
+        let policy = PermissionPolicy::new(PermissionMode::WorkspaceWrite)
+            .with_tool_requirement("bash", PermissionMode::DangerFullAccess);
+        let mut prompter = RecordingPrompter {
+            seen: Vec::new(),
+            allow: false,
+        };
+
+        assert!(matches!(
+            policy.authorize("bash", "echo hi", Some(&mut prompter)),
+            PermissionOutcome::Deny { reason } if reason == "not now"
         ));
     }
 }

rust/crates/runtime/src/prompt.rs

@@ -201,6 +201,7 @@ fn discover_instruction_files(cwd: &Path) -> std::io::Result<Vec<ContextFile>> {
             dir.join("CLAUDE.md"),
             dir.join("CLAUDE.local.md"),
             dir.join(".claude").join("CLAUDE.md"),
+            dir.join(".claude").join("instructions.md"),
         ] {
             push_context_file(&mut files, candidate)?;
         }
@@ -468,6 +469,10 @@ mod tests {
         std::env::temp_dir().join(format!("runtime-prompt-{nanos}"))
     }
 
+    fn env_lock() -> std::sync::MutexGuard<'static, ()> {
+        crate::test_env_lock()
+    }
+
     #[test]
     fn discovers_instruction_files_from_ancestor_chain() {
         let root = temp_dir();
@@ -477,10 +482,21 @@ mod tests {
         fs::write(root.join("CLAUDE.local.md"), "local instructions")
             .expect("write local instructions");
         fs::create_dir_all(root.join("apps")).expect("apps dir");
+        fs::create_dir_all(root.join("apps").join(".claude")).expect("apps claude dir");
         fs::write(root.join("apps").join("CLAUDE.md"), "apps instructions")
             .expect("write apps instructions");
+        fs::write(
+            root.join("apps").join(".claude").join("instructions.md"),
+            "apps dot claude instructions",
+        )
+        .expect("write apps dot claude instructions");
         fs::write(nested.join(".claude").join("CLAUDE.md"), "nested rules")
             .expect("write nested rules");
+        fs::write(
+            nested.join(".claude").join("instructions.md"),
+            "nested instructions",
+        )
+        .expect("write nested instructions");
 
         let context = ProjectContext::discover(&nested, "2026-03-31").expect("context should load");
         let contents = context
@@ -495,7 +511,9 @@ mod tests {
                 "root instructions",
                 "local instructions",
                 "apps instructions",
-                "nested rules"
+                "apps dot claude instructions",
+                "nested rules",
+                "nested instructions"
             ]
         );
         fs::remove_dir_all(root).expect("cleanup temp dir");
@@ -574,7 +592,12 @@ mod tests {
         )
         .expect("write settings");
 
+        let _guard = env_lock();
         let previous = std::env::current_dir().expect("cwd");
+        let original_home = std::env::var("HOME").ok();
+        let original_claude_home = std::env::var("CLAUDE_CONFIG_HOME").ok();
+        std::env::set_var("HOME", &root);
+        std::env::set_var("CLAUDE_CONFIG_HOME", root.join("missing-home"));
         std::env::set_current_dir(&root).expect("change cwd");
         let prompt = super::load_system_prompt(&root, "2026-03-31", "linux", "6.8")
             .expect("system prompt should load")
@@ -584,6 +607,16 @@ mod tests {
 ",
             );
         std::env::set_current_dir(previous).expect("restore cwd");
+        if let Some(value) = original_home {
+            std::env::set_var("HOME", value);
+        } else {
+            std::env::remove_var("HOME");
+        }
+        if let Some(value) = original_claude_home {
+            std::env::set_var("CLAUDE_CONFIG_HOME", value);
+        } else {
+            std::env::remove_var("CLAUDE_CONFIG_HOME");
+        }
 
         assert!(prompt.contains("Project rules"));
         assert!(prompt.contains("permissionMode"));
@@ -631,6 +664,29 @@ mod tests {
         assert!(rendered.chars().count() <= 4_000 + "\n\n[truncated]".chars().count());
     }
 
+    #[test]
+    fn discovers_dot_claude_instructions_markdown() {
+        let root = temp_dir();
+        let nested = root.join("apps").join("api");
+        fs::create_dir_all(nested.join(".claude")).expect("nested claude dir");
+        fs::write(
+            nested.join(".claude").join("instructions.md"),
+            "instruction markdown",
+        )
+        .expect("write instructions.md");
+
+        let context = ProjectContext::discover(&nested, "2026-03-31").expect("context should load");
+        assert!(context
+            .instruction_files
+            .iter()
+            .any(|file| file.path.ends_with(".claude/instructions.md")));
+        assert!(
+            render_instruction_files(&context.instruction_files).contains("instruction markdown")
+        );
+
+        fs::remove_dir_all(root).expect("cleanup temp dir");
+    }
+
     #[test]
     fn renders_instruction_file_metadata() {
         let rendered = render_instruction_files(&[ContextFile {

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/app.rs

@@ -2,7 +2,7 @@ use std::io::{self, Write};
 use std::path::PathBuf;
 
 use crate::args::{OutputFormat, PermissionMode};
-use crate::input::LineEditor;
+use crate::input::{LineEditor, ReadOutcome};
 use crate::render::{Spinner, TerminalRenderer};
 use runtime::{ConversationClient, ConversationMessage, RuntimeError, StreamEvent, UsageSummary};
 
@@ -111,16 +111,21 @@ impl CliApp {
     }
 
     pub fn run_repl(&mut self) -> io::Result<()> {
-        let editor = LineEditor::new("› ");
+        let mut editor = LineEditor::new("› ", Vec::new());
         println!("Rusty Claude CLI interactive mode");
         println!("Type /help for commands. Shift+Enter or Ctrl+J inserts a newline.");
 
-        while let Some(input) = editor.read_line()? {
-            if input.trim().is_empty() {
-                continue;
+        loop {
+            match editor.read_line()? {
+                ReadOutcome::Submit(input) => {
+                    if input.trim().is_empty() {
+                        continue;
+                    }
+                    self.handle_submission(&input, &mut io::stdout())?;
+                }
+                ReadOutcome::Cancel => continue,
+                ReadOutcome::Exit => break,
             }
-
-            self.handle_submission(&input, &mut io::stdout())?;
         }
 
         Ok(())

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

@@ -1,9 +1,8 @@
 use std::io::{self, IsTerminal, Write};
 
-use crossterm::cursor::MoveToColumn;
+use crossterm::cursor::{MoveDown, MoveToColumn, MoveUp};
 use crossterm::event::{self, Event, KeyCode, KeyEvent, KeyModifiers};
 use crossterm::queue;
-use crossterm::style::Print;
 use crossterm::terminal::{disable_raw_mode, enable_raw_mode, Clear, ClearType};
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -85,21 +84,124 @@ impl InputBuffer {
         self.buffer.clear();
         self.cursor = 0;
     }
+
+    pub fn replace(&mut self, value: impl Into<String>) {
+        self.buffer = value.into();
+        self.cursor = self.buffer.len();
+    }
+
+    #[must_use]
+    fn current_command_prefix(&self) -> Option<&str> {
+        if self.cursor != self.buffer.len() {
+            return None;
+        }
+        let prefix = &self.buffer[..self.cursor];
+        if prefix.contains(char::is_whitespace) || !prefix.starts_with('/') {
+            return None;
+        }
+        Some(prefix)
+    }
+
+    pub fn complete_slash_command(&mut self, candidates: &[String]) -> bool {
+        let Some(prefix) = self.current_command_prefix() else {
+            return false;
+        };
+
+        let matches = candidates
+            .iter()
+            .filter(|candidate| candidate.starts_with(prefix))
+            .map(String::as_str)
+            .collect::<Vec<_>>();
+        if matches.is_empty() {
+            return false;
+        }
+
+        let replacement = longest_common_prefix(&matches);
+        if replacement == prefix {
+            return false;
+        }
+
+        self.replace(replacement);
+        true
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct RenderedBuffer {
+    lines: Vec<String>,
+    cursor_row: u16,
+    cursor_col: u16,
+}
+
+impl RenderedBuffer {
+    #[must_use]
+    pub fn line_count(&self) -> usize {
+        self.lines.len()
+    }
+
+    fn write(&self, out: &mut impl Write) -> io::Result<()> {
+        for (index, line) in self.lines.iter().enumerate() {
+            if index > 0 {
+                writeln!(out)?;
+            }
+            write!(out, "{line}")?;
+        }
+        Ok(())
+    }
+
+    #[cfg(test)]
+    #[must_use]
+    pub fn lines(&self) -> &[String] {
+        &self.lines
+    }
+
+    #[cfg(test)]
+    #[must_use]
+    pub fn cursor_position(&self) -> (u16, u16) {
+        (self.cursor_row, self.cursor_col)
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ReadOutcome {
+    Submit(String),
+    Cancel,
+    Exit,
 }
 
 pub struct LineEditor {
     prompt: String,
+    continuation_prompt: String,
+    history: Vec<String>,
+    history_index: Option<usize>,
+    draft: Option<String>,
+    completions: Vec<String>,
 }
 
 impl LineEditor {
     #[must_use]
-    pub fn new(prompt: impl Into<String>) -> Self {
+    pub fn new(prompt: impl Into<String>, completions: Vec<String>) -> Self {
         Self {
             prompt: prompt.into(),
+            continuation_prompt: String::from("> "),
+            history: Vec::new(),
+            history_index: None,
+            draft: None,
+            completions,
         }
     }
 
-    pub fn read_line(&self) -> io::Result<Option<String>> {
+    pub fn push_history(&mut self, entry: impl Into<String>) {
+        let entry = entry.into();
+        if entry.trim().is_empty() {
+            return;
+        }
+        self.history.push(entry);
+        self.history_index = None;
+        self.draft = None;
+    }
+
+    pub fn read_line(&mut self) -> io::Result<ReadOutcome> {
         if !io::stdin().is_terminal() || !io::stdout().is_terminal() {
             return self.read_line_fallback();
         }
@@ -107,29 +209,43 @@ impl LineEditor {
         enable_raw_mode()?;
         let mut stdout = io::stdout();
         let mut input = InputBuffer::new();
-        self.redraw(&mut stdout, &input)?;
+        let mut rendered_lines = 1usize;
+        self.redraw(&mut stdout, &input, rendered_lines)?;
 
         loop {
             let event = event::read()?;
             if let Event::Key(key) = event {
-                match Self::handle_key(key, &mut input) {
-                    EditorAction::Continue => self.redraw(&mut stdout, &input)?,
+                match self.handle_key(key, &mut input) {
+                    EditorAction::Continue => {
+                        rendered_lines = self.redraw(&mut stdout, &input, rendered_lines)?;
+                    }
                     EditorAction::Submit => {
                         disable_raw_mode()?;
                         writeln!(stdout)?;
-                        return Ok(Some(input.as_str().to_owned()));
+                        self.history_index = None;
+                        self.draft = None;
+                        return Ok(ReadOutcome::Submit(input.as_str().to_owned()));
                     }
                     EditorAction::Cancel => {
                         disable_raw_mode()?;
                         writeln!(stdout)?;
-                        return Ok(None);
+                        self.history_index = None;
+                        self.draft = None;
+                        return Ok(ReadOutcome::Cancel);
+                    }
+                    EditorAction::Exit => {
+                        disable_raw_mode()?;
+                        writeln!(stdout)?;
+                        self.history_index = None;
+                        self.draft = None;
+                        return Ok(ReadOutcome::Exit);
                     }
                 }
             }
         }
     }
 
-    fn read_line_fallback(&self) -> io::Result<Option<String>> {
+    fn read_line_fallback(&self) -> io::Result<ReadOutcome> {
         let mut stdout = io::stdout();
         write!(stdout, "{}", self.prompt)?;
         stdout.flush()?;
@@ -137,22 +253,32 @@ impl LineEditor {
         let mut buffer = String::new();
         let bytes_read = io::stdin().read_line(&mut buffer)?;
         if bytes_read == 0 {
-            return Ok(None);
+            return Ok(ReadOutcome::Exit);
         }
 
         while matches!(buffer.chars().last(), Some('\n' | '\r')) {
             buffer.pop();
         }
-        Ok(Some(buffer))
+        Ok(ReadOutcome::Submit(buffer))
     }
 
-    fn handle_key(key: KeyEvent, input: &mut InputBuffer) -> EditorAction {
+    #[allow(clippy::too_many_lines)]
+    fn handle_key(&mut self, key: KeyEvent, input: &mut InputBuffer) -> EditorAction {
         match key {
             KeyEvent {
                 code: KeyCode::Char('c'),
                 modifiers,
                 ..
-            } if modifiers.contains(KeyModifiers::CONTROL) => EditorAction::Cancel,
+            } if modifiers.contains(KeyModifiers::CONTROL) => {
+                if input.as_str().is_empty() {
+                    EditorAction::Exit
+                } else {
+                    input.clear();
+                    self.history_index = None;
+                    self.draft = None;
+                    EditorAction::Cancel
+                }
+            }
             KeyEvent {
                 code: KeyCode::Char('j'),
                 modifiers,
@@ -194,6 +320,25 @@ impl LineEditor {
                 input.move_right();
                 EditorAction::Continue
             }
+            KeyEvent {
+                code: KeyCode::Up, ..
+            } => {
+                self.navigate_history_up(input);
+                EditorAction::Continue
+            }
+            KeyEvent {
+                code: KeyCode::Down,
+                ..
+            } => {
+                self.navigate_history_down(input);
+                EditorAction::Continue
+            }
+            KeyEvent {
+                code: KeyCode::Tab, ..
+            } => {
+                input.complete_slash_command(&self.completions);
+                EditorAction::Continue
+            }
             KeyEvent {
                 code: KeyCode::Home,
                 ..
@@ -211,6 +356,8 @@ impl LineEditor {
                 code: KeyCode::Esc, ..
             } => {
                 input.clear();
+                self.history_index = None;
+                self.draft = None;
                 EditorAction::Cancel
             }
             KeyEvent {
@@ -219,22 +366,74 @@ impl LineEditor {
                 ..
             } if modifiers.is_empty() || modifiers == KeyModifiers::SHIFT => {
                 input.insert(ch);
+                self.history_index = None;
+                self.draft = None;
                 EditorAction::Continue
             }
             _ => EditorAction::Continue,
         }
     }
 
-    fn redraw(&self, out: &mut impl Write, input: &InputBuffer) -> io::Result<()> {
-        let display = input.as_str().replace('\n', "\\n\n> ");
+    fn navigate_history_up(&mut self, input: &mut InputBuffer) {
+        if self.history.is_empty() {
+            return;
+        }
+
+        match self.history_index {
+            Some(0) => {}
+            Some(index) => {
+                let next_index = index - 1;
+                input.replace(self.history[next_index].clone());
+                self.history_index = Some(next_index);
+            }
+            None => {
+                self.draft = Some(input.as_str().to_owned());
+                let next_index = self.history.len() - 1;
+                input.replace(self.history[next_index].clone());
+                self.history_index = Some(next_index);
+            }
+        }
+    }
+
+    fn navigate_history_down(&mut self, input: &mut InputBuffer) {
+        let Some(index) = self.history_index else {
+            return;
+        };
+
+        if index + 1 < self.history.len() {
+            let next_index = index + 1;
+            input.replace(self.history[next_index].clone());
+            self.history_index = Some(next_index);
+            return;
+        }
+
+        input.replace(self.draft.take().unwrap_or_default());
+        self.history_index = None;
+    }
+
+    fn redraw(
+        &self,
+        out: &mut impl Write,
+        input: &InputBuffer,
+        previous_line_count: usize,
+    ) -> io::Result<usize> {
+        let rendered = render_buffer(&self.prompt, &self.continuation_prompt, input);
+        if previous_line_count > 1 {
+            queue!(out, MoveUp(saturating_u16(previous_line_count - 1)))?;
+        }
+        queue!(out, MoveToColumn(0), Clear(ClearType::FromCursorDown),)?;
+        rendered.write(out)?;
         queue!(
             out,
+            MoveUp(saturating_u16(rendered.line_count().saturating_sub(1))),
             MoveToColumn(0),
-            Clear(ClearType::CurrentLine),
-            Print(&self.prompt),
-            Print(display),
         )?;
-        out.flush()
+        if rendered.cursor_row > 0 {
+            queue!(out, MoveDown(rendered.cursor_row))?;
+        }
+        queue!(out, MoveToColumn(rendered.cursor_col))?;
+        out.flush()?;
+        Ok(rendered.line_count())
     }
 }
 
@@ -243,11 +442,76 @@ enum EditorAction {
     Continue,
     Submit,
     Cancel,
+    Exit,
+}
+
+#[must_use]
+pub fn render_buffer(
+    prompt: &str,
+    continuation_prompt: &str,
+    input: &InputBuffer,
+) -> RenderedBuffer {
+    let before_cursor = &input.as_str()[..input.cursor];
+    let cursor_row = saturating_u16(before_cursor.chars().filter(|ch| *ch == '\n').count());
+    let cursor_line = before_cursor.rsplit('\n').next().unwrap_or_default();
+    let cursor_prompt = if cursor_row == 0 {
+        prompt
+    } else {
+        continuation_prompt
+    };
+    let cursor_col = saturating_u16(cursor_prompt.chars().count() + cursor_line.chars().count());
+
+    let mut lines = Vec::new();
+    for (index, line) in input.as_str().split('\n').enumerate() {
+        let prefix = if index == 0 {
+            prompt
+        } else {
+            continuation_prompt
+        };
+        lines.push(format!("{prefix}{line}"));
+    }
+    if lines.is_empty() {
+        lines.push(prompt.to_string());
+    }
+
+    RenderedBuffer {
+        lines,
+        cursor_row,
+        cursor_col,
+    }
+}
+
+#[must_use]
+fn longest_common_prefix(values: &[&str]) -> String {
+    let Some(first) = values.first() else {
+        return String::new();
+    };
+
+    let mut prefix = (*first).to_string();
+    for value in values.iter().skip(1) {
+        while !value.starts_with(&prefix) {
+            prefix.pop();
+            if prefix.is_empty() {
+                break;
+            }
+        }
+    }
+    prefix
+}
+
+#[must_use]
+fn saturating_u16(value: usize) -> u16 {
+    u16::try_from(value).unwrap_or(u16::MAX)
 }
 
 #[cfg(test)]
 mod tests {
-    use super::InputBuffer;
+    use super::{render_buffer, InputBuffer, LineEditor};
+    use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
+
+    fn key(code: KeyCode) -> KeyEvent {
+        KeyEvent::new(code, KeyModifiers::NONE)
+    }
 
     #[test]
     fn supports_basic_line_editing() {
@@ -266,4 +530,119 @@ mod tests {
         assert_eq!(input.as_str(), "hix");
         assert_eq!(input.cursor(), 2);
     }
+
+    #[test]
+    fn completes_unique_slash_command() {
+        let mut input = InputBuffer::new();
+        for ch in "/he".chars() {
+            input.insert(ch);
+        }
+
+        assert!(input.complete_slash_command(&[
+            "/help".to_string(),
+            "/hello".to_string(),
+            "/status".to_string(),
+        ]));
+        assert_eq!(input.as_str(), "/hel");
+
+        assert!(input.complete_slash_command(&["/help".to_string(), "/status".to_string()]));
+        assert_eq!(input.as_str(), "/help");
+    }
+
+    #[test]
+    fn ignores_completion_when_prefix_is_not_a_slash_command() {
+        let mut input = InputBuffer::new();
+        for ch in "hello".chars() {
+            input.insert(ch);
+        }
+
+        assert!(!input.complete_slash_command(&["/help".to_string()]));
+        assert_eq!(input.as_str(), "hello");
+    }
+
+    #[test]
+    fn history_navigation_restores_current_draft() {
+        let mut editor = LineEditor::new("› ", vec![]);
+        editor.push_history("/help");
+        editor.push_history("status report");
+
+        let mut input = InputBuffer::new();
+        for ch in "draft".chars() {
+            input.insert(ch);
+        }
+
+        let _ = editor.handle_key(key(KeyCode::Up), &mut input);
+        assert_eq!(input.as_str(), "status report");
+
+        let _ = editor.handle_key(key(KeyCode::Up), &mut input);
+        assert_eq!(input.as_str(), "/help");
+
+        let _ = editor.handle_key(key(KeyCode::Down), &mut input);
+        assert_eq!(input.as_str(), "status report");
+
+        let _ = editor.handle_key(key(KeyCode::Down), &mut input);
+        assert_eq!(input.as_str(), "draft");
+    }
+
+    #[test]
+    fn tab_key_completes_from_editor_candidates() {
+        let mut editor = LineEditor::new(
+            "› ",
+            vec![
+                "/help".to_string(),
+                "/status".to_string(),
+                "/session".to_string(),
+            ],
+        );
+        let mut input = InputBuffer::new();
+        for ch in "/st".chars() {
+            input.insert(ch);
+        }
+
+        let _ = editor.handle_key(key(KeyCode::Tab), &mut input);
+        assert_eq!(input.as_str(), "/status");
+    }
+
+    #[test]
+    fn renders_multiline_buffers_with_continuation_prompt() {
+        let mut input = InputBuffer::new();
+        for ch in "hello\nworld".chars() {
+            if ch == '\n' {
+                input.insert_newline();
+            } else {
+                input.insert(ch);
+            }
+        }
+
+        let rendered = render_buffer("› ", "> ", &input);
+        assert_eq!(
+            rendered.lines(),
+            &["› hello".to_string(), "> world".to_string()]
+        );
+        assert_eq!(rendered.cursor_position(), (1, 7));
+    }
+
+    #[test]
+    fn ctrl_c_exits_only_when_buffer_is_empty() {
+        let mut editor = LineEditor::new("› ", vec![]);
+        let mut empty = InputBuffer::new();
+        assert!(matches!(
+            editor.handle_key(
+                KeyEvent::new(KeyCode::Char('c'), KeyModifiers::CONTROL),
+                &mut empty,
+            ),
+            super::EditorAction::Exit
+        ));
+
+        let mut filled = InputBuffer::new();
+        filled.insert('x');
+        assert!(matches!(
+            editor.handle_key(
+                KeyEvent::new(KeyCode::Char('c'), KeyModifiers::CONTROL),
+                &mut filled,
+            ),
+            super::EditorAction::Cancel
+        ));
+        assert!(filled.as_str().is_empty());
+    }
 }

rust/crates/tools/src/lib.rs

@@ -6,7 +6,7 @@ use std::time::{Duration, Instant};
 use reqwest::blocking::Client;
 use runtime::{
     edit_file, execute_bash, glob_search, grep_search, read_file, write_file, BashCommandInput,
-    GrepSearchInput,
+    GrepSearchInput, PermissionMode,
 };
 use serde::{Deserialize, Serialize};
 use serde_json::{json, Value};
@@ -45,6 +45,7 @@ pub struct ToolSpec {
     pub name: &'static str,
     pub description: &'static str,
     pub input_schema: Value,
+    pub required_permission: PermissionMode,
 }
 
 #[must_use]
@@ -61,11 +62,16 @@ 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
             }),
+            required_permission: PermissionMode::DangerFullAccess,
         },
         ToolSpec {
             name: "read_file",
@@ -80,6 +86,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["path"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::ReadOnly,
         },
         ToolSpec {
             name: "write_file",
@@ -93,6 +100,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["path", "content"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::WorkspaceWrite,
         },
         ToolSpec {
             name: "edit_file",
@@ -108,6 +116,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["path", "old_string", "new_string"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::WorkspaceWrite,
         },
         ToolSpec {
             name: "glob_search",
@@ -121,6 +130,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["pattern"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::ReadOnly,
         },
         ToolSpec {
             name: "grep_search",
@@ -146,6 +156,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["pattern"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::ReadOnly,
         },
         ToolSpec {
             name: "WebFetch",
@@ -160,6 +171,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["url", "prompt"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::ReadOnly,
         },
         ToolSpec {
             name: "WebSearch",
@@ -180,6 +192,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["query"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::ReadOnly,
         },
         ToolSpec {
             name: "TodoWrite",
@@ -207,6 +220,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["todos"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::WorkspaceWrite,
         },
         ToolSpec {
             name: "Skill",
@@ -220,6 +234,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["skill"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::ReadOnly,
         },
         ToolSpec {
             name: "Agent",
@@ -236,6 +251,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["description", "prompt"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::DangerFullAccess,
         },
         ToolSpec {
             name: "ToolSearch",
@@ -249,6 +265,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["query"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::ReadOnly,
         },
         ToolSpec {
             name: "NotebookEdit",
@@ -265,6 +282,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["notebook_path"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::WorkspaceWrite,
         },
         ToolSpec {
             name: "Sleep",
@@ -277,6 +295,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["duration_ms"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::ReadOnly,
         },
         ToolSpec {
             name: "SendUserMessage",
@@ -297,6 +316,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["message", "status"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::ReadOnly,
         },
         ToolSpec {
             name: "Config",
@@ -312,6 +332,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["setting"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::WorkspaceWrite,
         },
         ToolSpec {
             name: "StructuredOutput",
@@ -320,6 +341,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "type": "object",
                 "additionalProperties": true
             }),
+            required_permission: PermissionMode::ReadOnly,
         },
         ToolSpec {
             name: "REPL",
@@ -334,6 +356,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["code", "language"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::DangerFullAccess,
         },
         ToolSpec {
             name: "PowerShell",
@@ -349,6 +372,7 @@ pub fn mvp_tool_specs() -> Vec<ToolSpec> {
                 "required": ["command"],
                 "additionalProperties": false
             }),
+            required_permission: PermissionMode::DangerFullAccess,
         },
     ]
 }
@@ -2194,6 +2218,7 @@ fn execute_shell_command(
             structured_content: None,
             persisted_output_path: None,
             persisted_output_size: None,
+            sandbox_status: None,
         });
     }
 
@@ -2231,6 +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) {
@@ -2261,6 +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));
@@ -2287,6 +2314,7 @@ Command exceeded timeout of {timeout_ms} ms",
         structured_content: None,
         persisted_output_path: None,
         persisted_output_size: None,
+        sandbox_status: None,
     })
 }