[codex] Remove child AGENTS.md prompt experiment

codex-rs/core/config.schema.json

@@ -446,9 +446,6 @@
             "browser_use_external": {
               "type": "boolean"
             },
-            "child_agents_md": {
-              "type": "boolean"
-            },
             "chronicle": {
               "type": "boolean"
             },
@@ -4689,9 +4686,6 @@
         "browser_use_external": {
           "type": "boolean"
         },
-        "child_agents_md": {
-          "type": "boolean"
-        },
         "chronicle": {
           "type": "boolean"
         },

codex-rs/core/src/agents_md.rs

@@ -26,8 +26,6 @@ use codex_config::merge_toml_values;
 use codex_config::project_root_markers_from_config;
 use codex_exec_server::ExecutorFileSystem;
 use codex_extension_api::UserInstructions;
-use codex_features::Feature;
-use codex_prompts::HIERARCHICAL_AGENTS_MESSAGE;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use codex_utils_path_uri::PathUri;
 use std::io;
@@ -72,13 +70,6 @@ pub(crate) async fn load_project_instructions(
         }
     }
 
-    if config.features.enabled(Feature::ChildAgentsMd) {
-        loaded.entries.push(InstructionEntry {
-            contents: HIERARCHICAL_AGENTS_MESSAGE.to_string(),
-            provenance: InstructionProvenance::Internal,
-        });
-    }
-
     (!loaded.is_empty()).then_some(loaded)
 }
 

codex-rs/core/src/agents_md_tests.rs

@@ -909,32 +909,6 @@ async fn secondary_environment_invalid_utf8_does_not_suppress_other_docs() {
     assert!(loaded.text().contains("secondary\u{FFFD}doc"));
 }
 
-#[tokio::test]
-async fn child_agents_guidance_is_appended_once_after_environment_groups() {
-    let primary = tempfile::tempdir().expect("primary tempdir");
-    let secondary = tempfile::tempdir().expect("secondary tempdir");
-    fs::write(primary.path().join("AGENTS.md"), "primary doc").unwrap();
-    fs::write(secondary.path().join("AGENTS.md"), "secondary doc").unwrap();
-    let mut config = make_config(&primary, /*limit*/ 4096, /*instructions*/ None).await;
-    config.features.enable(Feature::ChildAgentsMd).unwrap();
-    let environments = resolved_local_environments([
-        ("primary", config.cwd.clone()),
-        ("secondary", secondary.abs()),
-    ]);
-
-    let loaded = load_project_instructions(
-        &config.config,
-        /*user_instructions*/ None,
-        &environments,
-    )
-    .await
-    .expect("instructions expected");
-    let text = loaded.text();
-
-    assert_eq!(text.matches(HIERARCHICAL_AGENTS_MESSAGE).count(), 1);
-    assert!(text.ends_with(HIERARCHICAL_AGENTS_MESSAGE));
-}
-
 /// If there are existing system instructions but AGENTS.md docs are
 /// missing we expect the original instructions to be returned unchanged.
 #[tokio::test]
@@ -1098,32 +1072,6 @@ async fn agents_md_paths_preserve_symlinked_cwd() {
     assert_eq!(res, "project doc");
 }
 
-#[tokio::test]
-async fn child_agents_message_after_global_instructions_uses_plain_separator() {
-    let tmp = tempfile::tempdir().expect("tempdir");
-    let mut cfg = make_config(&tmp, /*limit*/ 4096, Some("global doc")).await;
-    cfg.features.enable(Feature::ChildAgentsMd).unwrap();
-
-    let loaded = load_agents_md(&cfg).await.expect("instructions expected");
-    let global_agents = cfg.codex_home.join(DEFAULT_AGENTS_MD_FILENAME);
-    let expected = LoadedAgentsMd {
-        user_instructions: Some(UserInstructions {
-            text: "global doc".to_string(),
-            source: global_agents,
-        }),
-        entries: vec![InstructionEntry {
-            contents: HIERARCHICAL_AGENTS_MESSAGE.to_string(),
-            provenance: InstructionProvenance::Internal,
-        }],
-    };
-
-    assert_eq!(loaded, expected);
-    assert_eq!(
-        loaded.text(),
-        format!("global doc\n\n{HIERARCHICAL_AGENTS_MESSAGE}")
-    );
-}
-
 #[tokio::test]
 async fn instruction_sources_include_global_before_agents_md_docs() {
     let tmp = tempfile::tempdir().expect("tempdir");
@@ -1162,50 +1110,6 @@ async fn instruction_sources_include_global_before_agents_md_docs() {
     );
 }
 
-#[tokio::test]
-async fn child_agents_message_after_project_docs_is_not_an_instruction_source() {
-    let tmp = tempfile::tempdir().expect("tempdir");
-    fs::write(tmp.path().join("AGENTS.md"), "project doc").unwrap();
-
-    let mut cfg = make_config(&tmp, /*limit*/ 4096, Some("global doc")).await;
-    cfg.features.enable(Feature::ChildAgentsMd).unwrap();
-    let global_agents = cfg.codex_home.join(DEFAULT_AGENTS_MD_FILENAME);
-    fs::create_dir_all(&cfg.codex_home).unwrap();
-    fs::write(&global_agents, "global doc").unwrap();
-
-    let loaded = load_agents_md(&cfg).await.expect("instructions expected");
-    let project_agents = cfg.cwd.join("AGENTS.md");
-
-    let expected = LoadedAgentsMd {
-        user_instructions: Some(UserInstructions {
-            text: "global doc".to_string(),
-            source: global_agents.clone(),
-        }),
-        entries: vec![
-            InstructionEntry {
-                contents: "project doc".to_string(),
-                provenance: project_provenance(project_agents.clone(), cfg.cwd.clone()),
-            },
-            InstructionEntry {
-                contents: HIERARCHICAL_AGENTS_MESSAGE.to_string(),
-                provenance: InstructionProvenance::Internal,
-            },
-        ],
-    };
-    assert_eq!(loaded, expected);
-    assert_eq!(
-        loaded.sources().collect::<Vec<_>>(),
-        vec![
-            PathUri::from_abs_path(&global_agents),
-            PathUri::from_abs_path(&project_agents),
-        ]
-    );
-    assert_eq!(
-        loaded.text(),
-        format!("global doc{AGENTS_MD_SEPARATOR}project doc\n\n{HIERARCHICAL_AGENTS_MESSAGE}")
-    );
-}
-
 /// AGENTS.override.md is preferred over AGENTS.md when both are present.
 #[tokio::test]
 async fn agents_local_md_preferred() {

codex-rs/core/tests/suite/mod.rs

@@ -57,7 +57,6 @@ mod extension_sandbox;
 mod fork_thread;
 #[cfg(not(target_os = "windows"))]
 mod guardian_review;
-mod hierarchical_agents;
 #[cfg(not(target_os = "windows"))]
 mod hooks;
 #[cfg(not(target_os = "windows"))]

codex-rs/core/tests/suite/unstable_features_warning.rs

@@ -21,14 +21,14 @@ async fn emits_warning_when_unstable_features_enabled_via_config() {
     let mut config = load_default_config_for_test(&home).await;
     config
         .features
-        .enable(Feature::ChildAgentsMd)
+        .enable(Feature::ApplyPatchStreamingEvents)
         .expect("test config should allow feature update");
     let user_config_path =
         AbsolutePathBuf::from_absolute_path(config.codex_home.join(CONFIG_TOML_FILE))
             .expect("absolute user config path");
     config.config_layer_stack = config.config_layer_stack.with_user_config(
         &user_config_path,
-        toml! { features = { child_agents_md = true } }.into(),
+        toml! { features = { apply_patch_streaming_events = true } }.into(),
     );
 
     let thread_manager = codex_core::test_support::thread_manager_with_models_provider(
@@ -56,7 +56,7 @@ async fn emits_warning_when_unstable_features_enabled_via_config() {
     let EventMsg::Warning(WarningEvent { message }) = warning else {
         panic!("expected warning event");
     };
-    assert!(message.contains("child_agents_md"));
+    assert!(message.contains("apply_patch_streaming_events"));
     assert!(message.contains("Under-development features enabled"));
     assert!(message.contains("suppress_unstable_features_warning = true"));
 }
@@ -67,15 +67,15 @@ async fn suppresses_warning_when_configured() {
     let mut config = load_default_config_for_test(&home).await;
     config
         .features
-        .enable(Feature::ChildAgentsMd)
+        .enable(Feature::ApplyPatchStreamingEvents)
         .expect("test config should allow feature update");
     config.suppress_unstable_features_warning = true;
     let user_config_path =
         AbsolutePathBuf::from_absolute_path(config.codex_home.join(CONFIG_TOML_FILE))
             .expect("absolute user config path");
     config.config_layer_stack = config.config_layer_stack.with_user_config(
         &user_config_path,
-        toml! { features = { child_agents_md = true } }.into(),
+        toml! { features = { apply_patch_streaming_events = true } }.into(),
     );
 
     let thread_manager = codex_core::test_support::thread_manager_with_models_provider(

codex-rs/features/src/lib.rs

@@ -132,8 +132,6 @@ pub enum Feature {
     LocalThreadStoreCompression,
     /// Enable the Chronicle sidecar for passive screen-context memories.
     Chronicle,
-    /// Append additional AGENTS.md guidance to user instructions.
-    ChildAgentsMd,
     /// Compress request bodies (zstd) when sending streaming requests to codex-backend.
     EnableRequestCompression,
     /// Start the managed network proxy for sandboxed sessions.
@@ -910,12 +908,6 @@ pub const FEATURES: &[FeatureSpec] = &[
         stage: Stage::UnderDevelopment,
         default_enabled: false,
     },
-    FeatureSpec {
-        id: Feature::ChildAgentsMd,
-        key: "child_agents_md",
-        stage: Stage::UnderDevelopment,
-        default_enabled: false,
-    },
     FeatureSpec {
         id: Feature::ApplyPatchFreeform,
         key: "apply_patch_freeform",

codex-rs/features/src/tests.rs

@@ -707,12 +707,15 @@ fn materialize_resolved_enabled_writes_all_features_and_preserves_custom_config(
 #[test]
 fn unstable_warning_event_only_mentions_enabled_under_development_features() {
     let mut configured_features = Table::new();
-    configured_features.insert("child_agents_md".to_string(), TomlValue::Boolean(true));
+    configured_features.insert(
+        "apply_patch_streaming_events".to_string(),
+        TomlValue::Boolean(true),
+    );
     configured_features.insert("personality".to_string(), TomlValue::Boolean(true));
     configured_features.insert("unknown".to_string(), TomlValue::Boolean(true));
 
     let mut features = Features::with_defaults();
-    features.enable(Feature::ChildAgentsMd);
+    features.enable(Feature::ApplyPatchStreamingEvents);
 
     let warning = unstable_features_warning_event(
         Some(&configured_features),
@@ -725,7 +728,7 @@ fn unstable_warning_event_only_mentions_enabled_under_development_features() {
     let EventMsg::Warning(WarningEvent { message }) = warning.msg else {
         panic!("expected warning event");
     };
-    assert!(message.contains("child_agents_md"));
+    assert!(message.contains("apply_patch_streaming_events"));
     assert!(!message.contains("personality"));
     assert!(message.contains("/tmp/config.toml"));
 }

codex-rs/prompts/src/lib.rs

@@ -1,4 +1,3 @@
-mod agents;
 mod apply_patch;
 mod compact;
 mod goals;
@@ -7,7 +6,6 @@ mod realtime;
 mod review_exit;
 mod review_request;
 
-pub use agents::HIERARCHICAL_AGENTS_MESSAGE;
 pub use apply_patch::APPLY_PATCH_TOOL_INSTRUCTIONS;
 pub use compact::SUMMARIZATION_PROMPT;
 pub use compact::SUMMARY_PREFIX;

docs/agents_md.md

@@ -1,7 +1,3 @@
 # AGENTS.md
 
 For information about AGENTS.md, see [this documentation](https://developers.openai.com/codex/guides/agents-md).
-
-## Hierarchical agents message
-
-When the `child_agents_md` feature flag is enabled (via `[features]` in `config.toml`), Codex appends additional guidance about AGENTS.md scope and precedence to the user instructions message and emits that message even when no AGENTS.md is present.