chore(config) rm experimental_use_freeform_apply_patch (#22565)

## Summary
Get rid of the `experimental_use_freeform_apply_patch` config option,
since it is now encoded in model config. No deprecation message since it
has been experimental this entire time.

## Testing
- [x] Updated unit tests

---------

Co-authored-by: Codex <noreply@openai.com>

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

@@ -4237,7 +4237,6 @@ async fn legacy_toggles_map_to_features() -> std::io::Result<()> {
     let codex_home = TempDir::new()?;
     let cfg = ConfigToml {
         experimental_use_unified_exec_tool: Some(true),
-        experimental_use_freeform_apply_patch: Some(true),
         ..Default::default()
     };
 
@@ -4248,11 +4247,8 @@ async fn legacy_toggles_map_to_features() -> std::io::Result<()> {
     )
     .await?;
 
-    assert!(config.features.enabled(Feature::ApplyPatchFreeform));
     assert!(config.features.enabled(Feature::UnifiedExec));
 
-    assert!(config.include_apply_patch_tool);
-
     assert!(config.use_experimental_unified_exec_tool);
 
     Ok(())

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

@@ -269,13 +269,6 @@ fn explicit_feature_settings_in_config(cfg: &ConfigToml) -> Vec<(String, Feature
             enabled,
         ));
     }
-    if let Some(enabled) = cfg.experimental_use_freeform_apply_patch {
-        explicit_settings.push((
-            "experimental_use_freeform_apply_patch".to_string(),
-            Feature::ApplyPatchFreeform,
-            enabled,
-        ));
-    }
     for (profile_name, profile) in &cfg.profiles {
         if let Some(features) = profile.features.as_ref() {
             for (key, enabled) in features.entries() {
@@ -288,13 +281,6 @@ fn explicit_feature_settings_in_config(cfg: &ConfigToml) -> Vec<(String, Feature
                 }
             }
         }
-        if let Some(enabled) = profile.include_apply_patch_tool {
-            explicit_settings.push((
-                format!("profiles.{profile_name}.include_apply_patch_tool"),
-                Feature::ApplyPatchFreeform,
-                enabled,
-            ));
-        }
         if let Some(enabled) = profile.experimental_use_unified_exec_tool {
             explicit_settings.push((
                 format!("profiles.{profile_name}.experimental_use_unified_exec_tool"),
@@ -302,13 +288,6 @@ fn explicit_feature_settings_in_config(cfg: &ConfigToml) -> Vec<(String, Feature
                 enabled,
             ));
         }
-        if let Some(enabled) = profile.experimental_use_freeform_apply_patch {
-            explicit_settings.push((
-                format!("profiles.{profile_name}.experimental_use_freeform_apply_patch"),
-                Feature::ApplyPatchFreeform,
-                enabled,
-            ));
-        }
     }
 
     explicit_settings
@@ -370,14 +349,11 @@ pub(crate) fn validate_feature_requirements_in_config_toml(
             FeatureConfigSource {
                 features: cfg.features.as_ref(),
                 include_apply_patch_tool: None,
-                experimental_use_freeform_apply_patch: cfg.experimental_use_freeform_apply_patch,
                 experimental_use_unified_exec_tool: cfg.experimental_use_unified_exec_tool,
             },
             FeatureConfigSource {
                 features: profile.features.as_ref(),
-                include_apply_patch_tool: profile.include_apply_patch_tool,
-                experimental_use_freeform_apply_patch: profile
-                    .experimental_use_freeform_apply_patch,
+                include_apply_patch_tool: None,
                 experimental_use_unified_exec_tool: profile.experimental_use_unified_exec_tool,
             },
             FeatureOverrides::default(),

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

@@ -1881,7 +1881,6 @@ pub struct ConfigOverrides {
     pub developer_instructions: Option<String>,
     pub personality: Option<Personality>,
     pub compact_prompt: Option<String>,
-    pub include_apply_patch_tool: Option<bool>,
     pub show_raw_agent_reasoning: Option<bool>,
     pub tools_web_search_request: Option<bool>,
     pub ephemeral: Option<bool>,
@@ -2196,7 +2195,6 @@ impl Config {
             developer_instructions,
             personality,
             compact_prompt,
-            include_apply_patch_tool: include_apply_patch_tool_override,
             show_raw_agent_reasoning,
             tools_web_search_request: override_tools_web_search_request,
             ephemeral,
@@ -2250,7 +2248,6 @@ impl Config {
         };
         let tool_suggest = resolve_tool_suggest_config(&cfg, &config_layer_stack);
         let feature_overrides = FeatureOverrides {
-            include_apply_patch_tool: include_apply_patch_tool_override,
             web_search_request: override_tools_web_search_request,
         };
 
@@ -2258,14 +2255,11 @@ impl Config {
             FeatureConfigSource {
                 features: cfg.features.as_ref(),
                 include_apply_patch_tool: None,
-                experimental_use_freeform_apply_patch: cfg.experimental_use_freeform_apply_patch,
                 experimental_use_unified_exec_tool: cfg.experimental_use_unified_exec_tool,
             },
             FeatureConfigSource {
                 features: config_profile.features.as_ref(),
-                include_apply_patch_tool: config_profile.include_apply_patch_tool,
-                experimental_use_freeform_apply_patch: config_profile
-                    .experimental_use_freeform_apply_patch,
+                include_apply_patch_tool: None,
                 experimental_use_unified_exec_tool: config_profile
                     .experimental_use_unified_exec_tool,
             },

codex-rs/core/src/session/config_lock.rs

@@ -194,7 +194,6 @@ fn drop_lockfile_inputs(lock_config: &mut ConfigToml) {
     lock_config.default_permissions = None;
     lock_config.permissions = None;
     lock_config.experimental_use_unified_exec_tool = None;
-    lock_config.experimental_use_freeform_apply_patch = None;
 }
 
 fn resolved_config_to_toml<Toml>(