fix: introduce AbsolutePathBuf as part of sandbox config

codex-rs/app-server-protocol/Cargo.toml

@@ -15,6 +15,7 @@ workspace = true
 anyhow = { workspace = true }
 clap = { workspace = true, features = ["derive"] }
 codex-protocol = { workspace = true }
+codex-utils-absolute-path = { workspace = true }
 mcp-types = { workspace = true }
 schemars = { workspace = true }
 serde = { workspace = true, features = ["derive"] }

codex-rs/app-server-protocol/src/protocol/v1.rs

@@ -16,6 +16,7 @@ use codex_protocol::protocol::ReviewDecision;
 use codex_protocol::protocol::SandboxPolicy;
 use codex_protocol::protocol::SessionSource;
 use codex_protocol::protocol::TurnAbortReason;
+use codex_utils_absolute_path::AbsolutePathBuf;
 use schemars::JsonSchema;
 use serde::Deserialize;
 use serde::Serialize;
@@ -359,7 +360,7 @@ pub struct Tools {
 #[serde(rename_all = "camelCase")]
 pub struct SandboxSettings {
     #[serde(default)]
-    pub writable_roots: Vec<PathBuf>,
+    pub writable_roots: Vec<AbsolutePathBuf>,
     pub network_access: Option<bool>,
     pub exclude_tmpdir_env_var: Option<bool>,
     pub exclude_slash_tmp: Option<bool>,

codex-rs/app-server-protocol/src/protocol/v2.rs

@@ -24,6 +24,7 @@ use codex_protocol::protocol::SessionSource as CoreSessionSource;
 use codex_protocol::protocol::TokenUsage as CoreTokenUsage;
 use codex_protocol::protocol::TokenUsageInfo as CoreTokenUsageInfo;
 use codex_protocol::user_input::UserInput as CoreUserInput;
+use codex_utils_absolute_path::AbsolutePathBuf;
 use mcp_types::ContentBlock as McpContentBlock;
 use mcp_types::Resource as McpResource;
 use mcp_types::ResourceTemplate as McpResourceTemplate;
@@ -420,7 +421,7 @@ pub enum SandboxPolicy {
     #[ts(rename_all = "camelCase")]
     WorkspaceWrite {
         #[serde(default)]
-        writable_roots: Vec<PathBuf>,
+        writable_roots: Vec<AbsolutePathBuf>,
         #[serde(default)]
         network_access: bool,
         #[serde(default)]

codex-rs/app-server/Cargo.toml

@@ -27,6 +27,7 @@ codex-protocol = { workspace = true }
 codex-app-server-protocol = { workspace = true }
 codex-feedback = { workspace = true }
 codex-rmcp-client = { workspace = true }
+codex-utils-absolute-path = { workspace = true }
 codex-utils-json-to-toml = { workspace = true }
 chrono = { workspace = true }
 serde = { workspace = true, features = ["derive"] }

codex-rs/app-server/tests/suite/codex_message_processor_flow.rs

@@ -410,7 +410,7 @@ async fn test_send_user_turn_updates_sandbox_and_cwd_between_turns() -> Result<(
             cwd: first_cwd.clone(),
             approval_policy: AskForApproval::Never,
             sandbox_policy: SandboxPolicy::WorkspaceWrite {
-                writable_roots: vec![first_cwd.clone()],
+                writable_roots: vec![first_cwd.try_into()?],
                 network_access: false,
                 exclude_tmpdir_env_var: false,
                 exclude_slash_tmp: false,

codex-rs/app-server/tests/suite/config.rs

@@ -14,6 +14,7 @@ use codex_protocol::config_types::ReasoningSummary;
 use codex_protocol::config_types::SandboxMode;
 use codex_protocol::config_types::Verbosity;
 use codex_protocol::openai_models::ReasoningEffort;
+use codex_utils_absolute_path::AbsolutePathBuf;
 use pretty_assertions::assert_eq;
 use std::collections::HashMap;
 use std::path::Path;
@@ -23,10 +24,16 @@ use tokio::time::timeout;
 const DEFAULT_READ_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(10);
 
 fn create_config_toml(codex_home: &Path) -> std::io::Result<()> {
+    let writable_root = if cfg!(windows) {
+        r"C:\Users\codex\AppData\Local\Temp"
+    } else {
+        "/tmp"
+    };
     let config_toml = codex_home.join("config.toml");
     std::fs::write(
         config_toml,
-        r#"
+        format!(
+            r#"
 model = "gpt-5.1-codex-max"
 approval_policy = "on-request"
 sandbox_mode = "workspace-write"
@@ -38,7 +45,7 @@ forced_chatgpt_workspace_id = "12345678-0000-0000-0000-000000000000"
 forced_login_method = "chatgpt"
 
 [sandbox_workspace_write]
-writable_roots = ["/tmp"]
+writable_roots = [{}]
 network_access = true
 exclude_tmpdir_env_var = true
 exclude_slash_tmp = true
@@ -56,6 +63,8 @@ model_verbosity = "medium"
 model_provider = "openai"
 chatgpt_base_url = "https://api.chatgpt.com"
 "#,
+            serde_json::json!(writable_root)
+        ),
     )
 }
 
@@ -75,12 +84,18 @@ async fn get_config_toml_parses_all_fields() -> Result<()> {
     .await??;
 
     let config: GetUserSavedConfigResponse = to_response(resp)?;
+    let writable_root = if cfg!(windows) {
+        r"C:\Users\codex\AppData\Local\Temp"
+    } else {
+        "/tmp"
+    };
+    let writable_root = AbsolutePathBuf::from_absolute_path(writable_root)?;
     let expected = GetUserSavedConfigResponse {
         config: UserSavedConfig {
             approval_policy: Some(AskForApproval::OnRequest),
             sandbox_mode: Some(SandboxMode::WorkspaceWrite),
             sandbox_settings: Some(SandboxSettings {
-                writable_roots: vec!["/tmp".into()],
+                writable_roots: vec![writable_root],
                 network_access: Some(true),
                 exclude_tmpdir_env_var: Some(true),
                 exclude_slash_tmp: Some(true),

codex-rs/app-server/tests/suite/v2/config_rpc.rs

@@ -135,29 +135,40 @@ view_image = false
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn config_read_includes_system_layer_and_overrides() -> Result<()> {
     let codex_home = TempDir::new()?;
+    let (user_dir, system_dir) = if cfg!(windows) {
+        (r"C:\Users\user", r"C:\System")
+    } else {
+        ("/user", "/system")
+    };
     write_config(
         &codex_home,
-        r#"
+        &format!(
+            r#"
 model = "gpt-user"
 approval_policy = "on-request"
 sandbox_mode = "workspace-write"
 
 [sandbox_workspace_write]
-writable_roots = ["/user"]
+writable_roots = [{}]
 network_access = true
 "#,
+            serde_json::json!(user_dir)
+        ),
     )?;
 
     let managed_path = codex_home.path().join("managed_config.toml");
     std::fs::write(
         &managed_path,
-        r#"
+        format!(
+            r#"
 model = "gpt-system"
 approval_policy = "never"
 
 [sandbox_workspace_write]
-writable_roots = ["/system"]
+writable_roots = [{}]
 "#,
+            serde_json::json!(system_dir)
+        ),
     )?;
 
     let managed_path_str = managed_path.display().to_string();
@@ -207,7 +218,7 @@ writable_roots = ["/system"]
         .sandbox_workspace_write
         .as_ref()
         .expect("sandbox workspace write");
-    assert_eq!(sandbox.writable_roots, vec![PathBuf::from("/system")]);
+    assert_eq!(sandbox.writable_roots, vec![PathBuf::from(system_dir)]);
     assert_eq!(
         origins
             .get("sandbox_workspace_write.writable_roots.0")
@@ -350,6 +361,11 @@ async fn config_batch_write_applies_multiple_edits() -> Result<()> {
     let mut mcp = McpProcess::new(codex_home.path()).await?;
     timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
 
+    let writable_root = if cfg!(windows) {
+        r"C:\Users\codex\AppData\Local\Temp"
+    } else {
+        "/tmp"
+    };
     let batch_id = mcp
         .send_config_batch_write_request(ConfigBatchWriteParams {
             file_path: Some(codex_home.path().join("config.toml").display().to_string()),
@@ -362,7 +378,7 @@ async fn config_batch_write_applies_multiple_edits() -> Result<()> {
                 ConfigEdit {
                     key_path: "sandbox_workspace_write".to_string(),
                     value: json!({
-                        "writable_roots": ["/tmp"],
+                        "writable_roots": [writable_root],
                         "network_access": false
                     }),
                     merge_strategy: MergeStrategy::Replace,
@@ -404,7 +420,7 @@ async fn config_batch_write_applies_multiple_edits() -> Result<()> {
         .sandbox_workspace_write
         .as_ref()
         .expect("sandbox workspace write");
-    assert_eq!(sandbox.writable_roots, vec![PathBuf::from("/tmp")]);
+    assert_eq!(sandbox.writable_roots, vec![PathBuf::from(writable_root)]);
     assert!(!sandbox.network_access);
 
     Ok(())

codex-rs/app-server/tests/suite/v2/turn_start.rs

@@ -532,7 +532,7 @@ async fn turn_start_updates_sandbox_and_cwd_between_turns_v2() -> Result<()> {
             cwd: Some(first_cwd.clone()),
             approval_policy: Some(codex_app_server_protocol::AskForApproval::Never),
             sandbox_policy: Some(codex_app_server_protocol::SandboxPolicy::WorkspaceWrite {
-                writable_roots: vec![first_cwd.clone()],
+                writable_roots: vec![first_cwd.try_into()?],
                 network_access: false,
                 exclude_tmpdir_env_var: false,
                 exclude_slash_tmp: false,