config: remove dead profile sandbox fallback (#25943)

## Why

`profile_sandbox_mode` was left over from the old selected legacy
profile path. Production now always derives permissions without that
value, and legacy profile contents are ignored, so keeping a parameter
that is always `None` makes `derive_permission_profile` look like it
still supports a fallback that no longer exists.

## What Changed

- Removed the `profile_sandbox_mode` argument from
`ConfigToml::derive_permission_profile`.
- Updated the production caller and legacy sandbox-policy test helper to
match.
- Dropped the stale unselected legacy-profile sandbox test that only
protected the removed fallback shape.

## Verification

- `just test -p codex-config`
- `just test -p codex-core 'config::'`


---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/25943).
* #25926
* __->__ #25943

codex-rs/config/src/config_toml.rs

@@ -724,16 +724,13 @@ impl ConfigToml {
     pub async fn derive_permission_profile(
         &self,
         sandbox_mode_override: Option<SandboxMode>,
-        profile_sandbox_mode: Option<SandboxMode>,
         windows_sandbox_level: WindowsSandboxLevel,
         active_project: Option<&ProjectConfig>,
         permission_profile_constraint: Option<&crate::Constrained<PermissionProfile>>,
     ) -> PermissionProfile {
-        let sandbox_mode_was_explicit = sandbox_mode_override.is_some()
-            || profile_sandbox_mode.is_some()
-            || self.sandbox_mode.is_some();
+        let sandbox_mode_was_explicit =
+            sandbox_mode_override.is_some() || self.sandbox_mode.is_some();
         let resolved_sandbox_mode = sandbox_mode_override
-            .or(profile_sandbox_mode)
             .or(self.sandbox_mode)
             .or(if sandbox_mode_was_explicit {
                 None

codex-rs/core/src/config/config_tests.rs

@@ -32,7 +32,6 @@ use codex_config::permissions_toml::NetworkToml;
 use codex_config::permissions_toml::PermissionProfileToml;
 use codex_config::permissions_toml::PermissionsToml;
 use codex_config::permissions_toml::WorkspaceRootsToml;
-use codex_config::profile_toml::ConfigProfile;
 use codex_config::types::AppToolApproval;
 use codex_config::types::ApprovalsReviewer;
 use codex_config::types::BundledSkillsConfig;
@@ -165,7 +164,6 @@ fn http_mcp(url: &str) -> McpServerConfig {
 async fn derive_legacy_sandbox_policy_for_test(
     cfg: &ConfigToml,
     sandbox_mode_override: Option<SandboxMode>,
-    profile_sandbox_mode: Option<SandboxMode>,
     windows_sandbox_level: WindowsSandboxLevel,
     active_project: Option<&ProjectConfig>,
     permission_profile_constraint: Option<&Constrained<PermissionProfile>>,
@@ -173,7 +171,6 @@ async fn derive_legacy_sandbox_policy_for_test(
     let permission_profile = cfg
         .derive_permission_profile(
             sandbox_mode_override,
-            profile_sandbox_mode,
             windows_sandbox_level,
             active_project,
             permission_profile_constraint,
@@ -3530,7 +3527,6 @@ network_access = false  # This should be ignored.
     let resolution = derive_legacy_sandbox_policy_for_test(
         &sandbox_full_access_cfg,
         sandbox_mode_override,
-        /*profile_sandbox_mode*/ None,
         WindowsSandboxLevel::Disabled,
         /*active_project*/ None,
         /*permission_profile_constraint*/ None,
@@ -3551,7 +3547,6 @@ network_access = true  # This should be ignored.
     let resolution = derive_legacy_sandbox_policy_for_test(
         &sandbox_read_only_cfg,
         sandbox_mode_override,
-        /*profile_sandbox_mode*/ None,
         WindowsSandboxLevel::Disabled,
         /*active_project*/ None,
         /*permission_profile_constraint*/ None,
@@ -3583,7 +3578,6 @@ trust_level = "trusted"
     let resolution = derive_legacy_sandbox_policy_for_test(
         &sandbox_workspace_write_cfg,
         sandbox_mode_override,
-        /*profile_sandbox_mode*/ None,
         WindowsSandboxLevel::Disabled,
         /*active_project*/ None,
         /*permission_profile_constraint*/ None,
@@ -3623,7 +3617,6 @@ exclude_slash_tmp = true
     let resolution = derive_legacy_sandbox_policy_for_test(
         &sandbox_workspace_write_cfg,
         sandbox_mode_override,
-        /*profile_sandbox_mode*/ None,
         WindowsSandboxLevel::Disabled,
         /*active_project*/ None,
         /*permission_profile_constraint*/ None,
@@ -4998,38 +4991,6 @@ model = "gpt-project-local"
     Ok(())
 }
 
-#[tokio::test]
-async fn unselected_profile_sandbox_mode_is_ignored() -> std::io::Result<()> {
-    let codex_home = TempDir::new()?;
-    let mut profiles = HashMap::new();
-    profiles.insert(
-        "work".to_string(),
-        ConfigProfile {
-            sandbox_mode: Some(SandboxMode::DangerFullAccess),
-            ..Default::default()
-        },
-    );
-    let cfg = ConfigToml {
-        profiles,
-        sandbox_mode: Some(SandboxMode::ReadOnly),
-        ..Default::default()
-    };
-
-    let config = Config::load_from_base_config_with_overrides(
-        cfg,
-        ConfigOverrides::default(),
-        codex_home.abs(),
-    )
-    .await?;
-
-    assert_eq!(
-        config.legacy_sandbox_policy(),
-        SandboxPolicy::new_read_only_policy()
-    );
-
-    Ok(())
-}
-
 #[tokio::test]
 async fn feature_table_overrides_legacy_flags() -> std::io::Result<()> {
     let codex_home = TempDir::new()?;
@@ -8587,7 +8548,6 @@ trust_level = "untrusted"
     let resolution = derive_legacy_sandbox_policy_for_test(
         &cfg,
         /*sandbox_mode_override*/ None,
-        /*profile_sandbox_mode*/ None,
         WindowsSandboxLevel::Disabled,
         Some(&active_project),
         /*permission_profile_constraint*/ None,
@@ -8644,7 +8604,6 @@ async fn derive_sandbox_policy_falls_back_to_read_only_for_implicit_defaults() -
     let resolution = derive_legacy_sandbox_policy_for_test(
         &cfg,
         /*sandbox_mode_override*/ None,
-        /*profile_sandbox_mode*/ None,
         WindowsSandboxLevel::Disabled,
         Some(&active_project),
         Some(&constrained),
@@ -8697,7 +8656,6 @@ async fn derive_sandbox_policy_preserves_windows_downgrade_for_unsupported_fallb
     let resolution = derive_legacy_sandbox_policy_for_test(
         &cfg,
         /*sandbox_mode_override*/ None,
-        /*profile_sandbox_mode*/ None,
         WindowsSandboxLevel::Disabled,
         Some(&active_project),
         Some(&constrained),

codex-rs/core/src/config/mod.rs

@@ -2936,7 +2936,6 @@ impl Config {
             let mut permission_profile = cfg
                 .derive_permission_profile(
                     sandbox_mode,
-                    /*profile_sandbox_mode*/ None,
                     windows_sandbox_level,
                     Some(&active_project),
                     Some(&constrained_permission_profile),