feat(auto-review) policy config (#18959)

## Summary
Allow users to customize their own auto-review policy config.

## Testing
- [x] added config_tests

codex-rs/config/src/config_toml.rs

@@ -90,6 +90,10 @@ pub struct ConfigToml {
     /// ARC.
     pub approvals_reviewer: Option<ApprovalsReviewer>,
 
+    /// Optional policy instructions for the guardian auto-reviewer.
+    #[serde(default)]
+    pub auto_review: Option<AutoReviewToml>,
+
     #[serde(default)]
     pub shell_environment_policy: ShellEnvironmentPolicyToml,
 
@@ -401,6 +405,12 @@ pub struct ConfigToml {
     pub oss_provider: Option<String>,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, Default, PartialEq, Eq, JsonSchema)]
+pub struct AutoReviewToml {
+    /// Additional policy instructions inserted into the guardian prompt.
+    pub policy: Option<String>,
+}
+
 impl From<ConfigToml> for UserSavedConfig {
     fn from(config_toml: ConfigToml) -> Self {
         let profiles = config_toml

codex-rs/core/config.schema.json

@@ -292,6 +292,15 @@
         }
       ]
     },
+    "AutoReviewToml": {
+      "properties": {
+        "policy": {
+          "description": "Additional policy instructions inserted into the guardian prompt.",
+          "type": "string"
+        }
+      },
+      "type": "object"
+    },
     "BundledSkillsConfig": {
       "additionalProperties": false,
       "properties": {
@@ -2253,6 +2262,15 @@
       "default": null,
       "description": "Machine-local realtime audio device preferences used by realtime voice."
     },
+    "auto_review": {
+      "allOf": [
+        {
+          "$ref": "#/definitions/AutoReviewToml"
+        }
+      ],
+      "default": null,
+      "description": "Optional policy instructions for the guardian auto-reviewer."
+    },
     "background_terminal_max_timeout": {
       "description": "Maximum poll window for background terminal output (`write_stdin`), in milliseconds. Default: `300000` (5 minutes).",
       "format": "uint64",

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

@@ -10,6 +10,7 @@ use assert_matches::assert_matches;
 use codex_config::CONFIG_TOML_FILE;
 use codex_config::config_toml::AgentRoleToml;
 use codex_config::config_toml::AgentsToml;
+use codex_config::config_toml::AutoReviewToml;
 use codex_config::config_toml::ConfigToml;
 use codex_config::config_toml::ProjectConfig;
 use codex_config::config_toml::RealtimeAudioConfig;
@@ -3706,6 +3707,116 @@ async fn load_config_uses_requirements_guardian_policy_config() -> std::io::Resu
     Ok(())
 }
 
+#[test]
+fn config_toml_deserializes_auto_review_policy() {
+    let cfg = toml::from_str::<ConfigToml>(
+        r#"
+[auto_review]
+policy = "Use the user-configured guardian policy."
+"#,
+    )
+    .expect("TOML deserialization should succeed");
+
+    assert_eq!(
+        cfg.auto_review
+            .as_ref()
+            .and_then(|auto_review| auto_review.policy.as_deref()),
+        Some("Use the user-configured guardian policy.")
+    );
+}
+
+#[tokio::test]
+async fn load_config_uses_auto_review_guardian_policy_config() -> std::io::Result<()> {
+    let codex_home = TempDir::new()?;
+    let cfg = ConfigToml {
+        auto_review: Some(AutoReviewToml {
+            policy: Some("  Use the user-configured guardian policy.  ".to_string()),
+        }),
+        ..Default::default()
+    };
+
+    let config = Config::load_from_base_config_with_overrides(
+        cfg,
+        ConfigOverrides {
+            cwd: Some(codex_home.path().to_path_buf()),
+            ..Default::default()
+        },
+        codex_home.abs(),
+    )
+    .await?;
+
+    assert_eq!(
+        config.guardian_policy_config.as_deref(),
+        Some("Use the user-configured guardian policy.")
+    );
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn requirements_guardian_policy_beats_auto_review() -> std::io::Result<()> {
+    let codex_home = TempDir::new()?;
+    let config_layer_stack = ConfigLayerStack::new(
+        Vec::new(),
+        Default::default(),
+        crate::config_loader::ConfigRequirementsToml {
+            guardian_policy_config: Some("Use the managed guardian policy.".to_string()),
+            ..Default::default()
+        },
+    )
+    .map_err(std::io::Error::other)?;
+    let cfg = ConfigToml {
+        auto_review: Some(AutoReviewToml {
+            policy: Some("Use the user-configured guardian policy.".to_string()),
+        }),
+        ..Default::default()
+    };
+
+    let config = Config::load_config_with_layer_stack(
+        LOCAL_FS.as_ref(),
+        cfg,
+        ConfigOverrides {
+            cwd: Some(codex_home.path().to_path_buf()),
+            ..Default::default()
+        },
+        codex_home.abs(),
+        config_layer_stack,
+    )
+    .await?;
+
+    assert_eq!(
+        config.guardian_policy_config.as_deref(),
+        Some("Use the managed guardian policy.")
+    );
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn load_config_ignores_empty_auto_review_guardian_policy_config() -> std::io::Result<()> {
+    let codex_home = TempDir::new()?;
+    let cfg = ConfigToml {
+        auto_review: Some(AutoReviewToml {
+            policy: Some("   ".to_string()),
+        }),
+        ..Default::default()
+    };
+
+    let config = Config::load_from_base_config_with_overrides(
+        cfg,
+        ConfigOverrides {
+            cwd: Some(codex_home.path().to_path_buf()),
+            ..Default::default()
+        },
+        codex_home.abs(),
+    )
+    .await?;
+
+    assert_eq!(config.guardian_policy_config, None);
+
+    Ok(())
+}
+
 #[tokio::test]
 async fn load_config_ignores_empty_requirements_guardian_policy_config() -> std::io::Result<()> {
     let codex_home = TempDir::new()?;

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

@@ -293,7 +293,7 @@ pub struct Config {
     /// Developer instructions override injected as a separate message.
     pub developer_instructions: Option<String>,
 
-    /// Guardian-specific tenant policy config override from requirements.toml.
+    /// Guardian-specific policy config override from requirements.toml or config.toml.
     /// This is inserted into the fixed guardian prompt template under the
     /// `# Policy Configuration` section rather than replacing the whole
     /// guardian developer prompt.
@@ -2026,7 +2026,14 @@ impl Config {
             .or(cfg.include_environment_context)
             .unwrap_or(true);
         let guardian_policy_config =
-            guardian_policy_config_from_requirements(config_layer_stack.requirements_toml());
+            guardian_policy_config_from_requirements(config_layer_stack.requirements_toml())
+                .or_else(|| {
+                    cfg.auto_review
+                        .as_ref()
+                        .and_then(|auto_review| normalize_guardian_policy_config(
+                            auto_review.policy.as_deref(),
+                        ))
+                });
         let personality = personality
             .or(config_profile.personality)
             .or(cfg.personality)
@@ -2490,13 +2497,14 @@ pub(crate) fn uses_deprecated_instructions_file(config_layer_stack: &ConfigLayer
 fn guardian_policy_config_from_requirements(
     requirements_toml: &ConfigRequirementsToml,
 ) -> Option<String> {
-    requirements_toml
-        .guardian_policy_config
-        .as_deref()
-        .and_then(|value| {
-            let trimmed = value.trim();
-            (!trimmed.is_empty()).then(|| trimmed.to_string())
-        })
+    normalize_guardian_policy_config(requirements_toml.guardian_policy_config.as_deref())
+}
+
+fn normalize_guardian_policy_config(value: Option<&str>) -> Option<String> {
+    value.and_then(|value| {
+        let trimmed = value.trim();
+        (!trimmed.is_empty()).then(|| trimmed.to_string())
+    })
 }
 
 fn toml_uses_deprecated_instructions_file(value: &TomlValue) -> bool {