Fix Apple Container sandbox resource limits

crates/tools/src/sandbox/apple.rs

@@ -33,8 +33,9 @@ use super::paths::{
 };
 #[cfg(target_os = "macos")]
 use super::types::{
-    BuildImageResult, DEFAULT_SANDBOX_IMAGE, ManagedFilesMount, NetworkPolicy, SANDBOX_FILES_DIR,
-    SANDBOX_HOME_DIR, Sandbox, SandboxConfig, SandboxId, truncate_output_for_display,
+    BuildImageResult, DEFAULT_SANDBOX_IMAGE, ManagedFilesMount, NetworkPolicy, ResourceLimits,
+    SANDBOX_FILES_DIR, SANDBOX_HOME_DIR, Sandbox, SandboxConfig, SandboxId,
+    truncate_output_for_display,
 };
 #[cfg(target_os = "macos")]
 use crate::error::{Error, Result};
@@ -466,8 +467,10 @@ impl AppleContainerSandbox {
         image: &str,
         tz: Option<&str>,
         volumes: &[String],
+        resource_limits: &ResourceLimits,
     ) -> std::result::Result<(), CreateError> {
-        let args = apple_container_run_args(name, image, tz, volumes);
+        let args = apple_container_run_args(name, image, tz, volumes, resource_limits)
+            .map_err(|error| CreateError::Other(error.to_string()))?;
 
         let output = tokio::process::Command::new("container")
             .args(&args)
@@ -865,7 +868,9 @@ impl Sandbox for AppleContainerSandbox {
 
             // Phase 2: Create a new container.
             info!(name, image = %image, attempt, "creating apple container");
-            match Self::run_container(&name, &image, tz, &volumes).await {
+            match Self::run_container(&name, &image, tz, &volumes, &self.config.resource_limits)
+                .await
+            {
                 Ok(()) => {},
                 Err(CreateError::AlreadyExists) => {
                     warn!(

crates/tools/src/sandbox/containers.rs

@@ -10,6 +10,8 @@ use {
 
 #[cfg(any(target_os = "macos", test))]
 use super::types::APPLE_CONTAINER_SAFE_WORKDIR;
+#[cfg(target_os = "macos")]
+use super::types::ResourceLimits;
 use {
     super::types::{
         GO_TOOL_INSTALLS, GOGCLI_MODULE_PATH, GOGCLI_VERSION, SANDBOX_HOME_DIR,
@@ -119,7 +121,8 @@ pub(crate) fn apple_container_run_args(
     image: &str,
     tz: Option<&str>,
     volumes: &[String],
-) -> Vec<String> {
+    resource_limits: &ResourceLimits,
+) -> Result<Vec<String>> {
     let mut args = vec![
         "run".to_string(),
         "-d".to_string(),
@@ -132,6 +135,25 @@ pub(crate) fn apple_container_run_args(
     if let Some(tz) = tz {
         args.extend(["-e".to_string(), format!("TZ={tz}")]);
     }
+    if let Some(ref memory) = resource_limits.memory_limit {
+        args.extend(["--memory".to_string(), memory.clone()]);
+    }
+    if let Some(cpus) = resource_limits.cpu_quota {
+        let cpus = cpus.to_string().parse::<i64>().map_err(|_| {
+            Error::message(format!(
+                "Apple Container requires cpu_quota to be a positive whole number, got {cpus}"
+            ))
+        })?;
+        if cpus < 1 {
+            return Err(Error::message(format!(
+                "Apple Container requires cpu_quota to be a positive whole number, got {cpus}"
+            )));
+        }
+        args.extend(["--cpus".to_string(), cpus.to_string()]);
+    }
+    if let Some(pids) = resource_limits.pids_max {
+        args.extend(["--ulimit".to_string(), format!("nproc={pids}")]);
+    }
     for volume in volumes {
         args.extend(["--volume".to_string(), volume.to_string()]);
     }
@@ -142,7 +164,7 @@ pub(crate) fn apple_container_run_args(
         "-c".to_string(),
         apple_container_bootstrap_command(),
     ]);
-    args
+    Ok(args)
 }
 
 #[cfg(any(target_os = "macos", test))]

crates/tools/src/sandbox/tests/apple.rs

@@ -185,7 +185,14 @@ fn test_apple_container_bootstrap_command_uses_portable_sleep() {
 
 #[test]
 fn test_apple_container_run_args_pin_workdir_and_bootstrap_home() {
-    let args = apple_container_run_args("moltis-sandbox-test", "ubuntu:25.10", Some("UTC"), &[]);
+    let args = apple_container_run_args(
+        "moltis-sandbox-test",
+        "ubuntu:25.10",
+        Some("UTC"),
+        &[],
+        &ResourceLimits::default(),
+    )
+    .unwrap();
     let expected = vec![
         "run",
         "-d",
@@ -208,9 +215,14 @@ fn test_apple_container_run_args_pin_workdir_and_bootstrap_home() {
 
 #[test]
 fn test_apple_container_run_args_with_home_volume() {
-    let args = apple_container_run_args("moltis-sandbox-test", "ubuntu:25.10", Some("UTC"), &[
-        "/tmp/home:/home/sandbox".to_string(),
-    ]);
+    let args = apple_container_run_args(
+        "moltis-sandbox-test",
+        "ubuntu:25.10",
+        Some("UTC"),
+        &["/tmp/home:/home/sandbox".to_string()],
+        &ResourceLimits::default(),
+    )
+    .unwrap();
     let expected = vec![
         "run",
         "-d",
@@ -239,7 +251,14 @@ fn test_apple_container_run_args_with_multiple_volumes() {
         "/tmp/home:/home/sandbox".to_string(),
         "/tmp/files:/home/sandbox/files:ro".to_string(),
     ];
-    let args = apple_container_run_args("moltis-sandbox-test", "ubuntu:25.10", None, &volumes);
+    let args = apple_container_run_args(
+        "moltis-sandbox-test",
+        "ubuntu:25.10",
+        None,
+        &volumes,
+        &ResourceLimits::default(),
+    )
+    .unwrap();
 
     assert_eq!(
         args.windows(2)
@@ -250,6 +269,55 @@ fn test_apple_container_run_args_with_multiple_volumes() {
     );
 }
 
+#[test]
+fn test_apple_container_run_args_apply_resource_limits() {
+    let args = apple_container_run_args(
+        "moltis-sandbox-test",
+        "ubuntu:25.10",
+        None,
+        &[],
+        &ResourceLimits {
+            memory_limit: Some("1G".into()),
+            cpu_quota: Some(2.0),
+            pids_max: Some(512),
+        },
+    )
+    .unwrap();
+
+    assert_eq!(
+        args.windows(2)
+            .filter(|window| matches!(window[0].as_str(), "--memory" | "--cpus" | "--ulimit"))
+            .map(|window| (window[0].as_str(), window[1].as_str()))
+            .collect::<Vec<_>>(),
+        vec![
+            ("--memory", "1G"),
+            ("--cpus", "2"),
+            ("--ulimit", "nproc=512")
+        ]
+    );
+}
+
+#[test]
+fn test_apple_container_run_args_reject_fractional_cpu_quota() {
+    let error = apple_container_run_args(
+        "moltis-sandbox-test",
+        "ubuntu:25.10",
+        None,
+        &[],
+        &ResourceLimits {
+            cpu_quota: Some(0.5),
+            ..Default::default()
+        },
+    )
+    .unwrap_err();
+
+    assert!(
+        error
+            .to_string()
+            .contains("cpu_quota to be a positive whole number")
+    );
+}
+
 #[cfg(target_os = "macos")]
 #[test]
 fn test_apple_container_managed_files_mount_coexists_with_home_persistence() {

docs/src/sandbox.md

@@ -448,7 +448,11 @@ How resource limits are applied depends on the backend:
 |-------|--------|-----------------|------|-----------------|----------------|
 | `memory_limit` | `--memory` | `--memory` | Wasmtime reservation | `ulimit -v` | `MemoryMax=` |
 | `cpu_quota` | `--cpus` | `--cpus` | epoch timeout | `ulimit -t` (seconds) | `CPUQuota=` |
-| `pids_max` | `--pids-limit` | `--pids-limit` | n/a | `ulimit -u` | `TasksMax=` |
+| `pids_max` | `--pids-limit` | `--ulimit nproc=` | n/a | `ulimit -u` | `TasksMax=` |
+
+Apple Container requires version 0.9 or newer to apply `pids_max`.
+Its `--cpus` option only accepts positive whole CPU counts, so fractional
+`cpu_quota` values are not supported by that backend.
 
 ## Comparison