diff --git a/codex-rs/core-plugins/src/loader.rs b/codex-rs/core-plugins/src/loader.rs
index 306c71960a..b2be23c45a 100644
--- a/codex-rs/core-plugins/src/loader.rs
+++ b/codex-rs/core-plugins/src/loader.rs
@@ -1114,297 +1114,5 @@ fn run_git(args: &[&str], cwd: Option<&Path>) -> Result<(), String> {
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-    use pretty_assertions::assert_eq;
-
-    #[test]
-    fn plugin_mcp_file_supports_mcp_servers_object_format() {
-        let parsed = serde_json::from_str::<PluginMcpFile>(
-            r#"{
-  "mcpServers": {
-    "sample": {
-      "command": "sample-mcp"
-    }
-  }
-}"#,
-        )
-        .expect("parse wrapped plugin mcp config")
-        .into_mcp_servers();
-
-        assert_eq!(
-            parsed,
-            HashMap::from([(
-                "sample".to_string(),
-                serde_json::json!({
-                    "command": "sample-mcp"
-                }),
-            )])
-        );
-    }
-
-    #[test]
-    fn plugin_mcp_file_supports_mcp_servers_object_format_with_metadata() {
-        let parsed = serde_json::from_str::<PluginMcpFile>(
-            r#"{
-  "$schema": "https://example.com/plugin-mcp.schema.json",
-  "mcpServers": {
-    "sample": {
-      "command": "sample-mcp"
-    }
-  }
-}"#,
-        )
-        .expect("parse plugin mcp config with metadata")
-        .into_mcp_servers();
-
-        assert_eq!(
-            parsed,
-            HashMap::from([(
-                "sample".to_string(),
-                serde_json::json!({
-                    "command": "sample-mcp"
-                }),
-            )])
-        );
-    }
-
-    #[test]
-    fn plugin_mcp_file_supports_top_level_server_map_format() {
-        let parsed = serde_json::from_str::<PluginMcpFile>(
-            r#"{
-  "linear": {
-    "type": "http",
-    "url": "https://mcp.linear.app/mcp"
-  }
-}"#,
-        )
-        .expect("parse flat plugin mcp config")
-        .into_mcp_servers();
-
-        assert_eq!(
-            parsed,
-            HashMap::from([(
-                "linear".to_string(),
-                serde_json::json!({
-                    "type": "http",
-                    "url": "https://mcp.linear.app/mcp"
-                }),
-            )])
-        );
-    }
-
-    #[test]
-    fn curated_plugin_cache_version_shortens_full_git_sha() {
-        assert_eq!(
-            curated_plugin_cache_version("0123456789abcdef0123456789abcdef01234567"),
-            "01234567"
-        );
-    }
-
-    #[test]
-    fn curated_plugin_cache_version_preserves_non_git_sha_versions() {
-        assert_eq!(
-            curated_plugin_cache_version("export-backup"),
-            "export-backup"
-        );
-        assert_eq!(curated_plugin_cache_version("0123456"), "0123456");
-    }
-
-    #[test]
-    fn load_plugin_hooks_discovers_default_hooks_file() {
-        let tmp = tempfile::tempdir().expect("tempdir");
-        let plugin_root =
-            AbsolutePathBuf::try_from(tmp.path().join("demo-plugin")).expect("plugin root");
-        fs::create_dir_all(plugin_root.join(".codex-plugin")).expect("create manifest dir");
-        fs::create_dir_all(plugin_root.join("hooks")).expect("create hooks dir");
-        fs::write(
-            plugin_root.join(".codex-plugin/plugin.json"),
-            r#"{ "name": "demo-plugin" }"#,
-        )
-        .expect("write manifest");
-        fs::write(
-            plugin_root.join("hooks/hooks.json"),
-            r#"{
-  "hooks": {
-    "PreToolUse": [
-      {
-        "matcher": "Bash",
-        "hooks": [{ "type": "command", "command": "echo default" }]
-      }
-    ]
-  }
-}"#,
-        )
-        .expect("write hooks");
-
-        let manifest = load_plugin_manifest(plugin_root.as_path()).expect("manifest");
-        let plugin_id = PluginId::parse("demo-plugin@test-marketplace").expect("plugin id");
-        let sources = load_plugin_hooks(&plugin_root, &plugin_id, &manifest.paths);
-
-        assert_eq!(sources.len(), 1);
-        assert_eq!(
-            sources[0].plugin_id,
-            PluginId::parse("demo-plugin@test-marketplace").expect("plugin id")
-        );
-        assert_eq!(sources[0].source_relative_path, "hooks/hooks.json");
-        assert_eq!(sources[0].hooks.handler_count(), 1);
-    }
-
-    #[test]
-    fn load_plugin_hooks_manifest_paths_replace_default_hooks_file() {
-        let tmp = tempfile::tempdir().expect("tempdir");
-        let plugin_root =
-            AbsolutePathBuf::try_from(tmp.path().join("demo-plugin")).expect("plugin root");
-        fs::create_dir_all(plugin_root.join(".codex-plugin")).expect("create manifest dir");
-        fs::create_dir_all(plugin_root.join("hooks")).expect("create hooks dir");
-        fs::write(
-            plugin_root.join(".codex-plugin/plugin.json"),
-            r#"{
-  "name": "demo-plugin",
-  "hooks": ["./hooks/one.json", "./hooks/two.json"]
-}"#,
-        )
-        .expect("write manifest");
-        fs::write(
-            plugin_root.join("hooks/hooks.json"),
-            r#"{
-  "hooks": {
-    "PreToolUse": [
-      {
-        "hooks": [{ "type": "command", "command": "echo ignored" }]
-      }
-    ]
-  }
-}"#,
-        )
-        .expect("write default hooks");
-        fs::write(
-            plugin_root.join("hooks/one.json"),
-            r#"{
-  "hooks": {
-    "PreToolUse": [
-      {
-        "hooks": [{ "type": "command", "command": "echo one" }]
-      }
-    ]
-  }
-}"#,
-        )
-        .expect("write first hooks");
-        fs::write(
-            plugin_root.join("hooks/two.json"),
-            r#"{
-  "hooks": {
-    "PostToolUse": [
-      {
-        "hooks": [{ "type": "command", "command": "echo two" }]
-      }
-    ]
-  }
-}"#,
-        )
-        .expect("write second hooks");
-
-        let manifest = load_plugin_manifest(plugin_root.as_path()).expect("manifest");
-        let plugin_id = PluginId::parse("demo-plugin@test-marketplace").expect("plugin id");
-        let sources = load_plugin_hooks(&plugin_root, &plugin_id, &manifest.paths);
-
-        assert_eq!(
-            sources
-                .iter()
-                .map(|source| source.source_relative_path.as_str())
-                .collect::<Vec<_>>(),
-            vec!["hooks/one.json", "hooks/two.json"]
-        );
-        assert_eq!(
-            sources
-                .iter()
-                .map(|source| source.hooks.handler_count())
-                .collect::<Vec<_>>(),
-            vec![1, 1]
-        );
-    }
-
-    #[test]
-    fn load_plugin_hooks_supports_inline_manifest_hooks() {
-        let tmp = tempfile::tempdir().expect("tempdir");
-        let plugin_root =
-            AbsolutePathBuf::try_from(tmp.path().join("demo-plugin")).expect("plugin root");
-        fs::create_dir_all(plugin_root.join(".codex-plugin")).expect("create manifest dir");
-        fs::write(
-            plugin_root.join(".codex-plugin/plugin.json"),
-            r#"{
-  "name": "demo-plugin",
-  "hooks": {
-    "hooks": {
-      "SessionStart": [
-        {
-          "matcher": "startup",
-          "hooks": [{ "type": "command", "command": "echo inline" }]
-        }
-      ]
-    }
-  }
-}"#,
-        )
-        .expect("write manifest");
-
-        let manifest = load_plugin_manifest(plugin_root.as_path()).expect("manifest");
-        let plugin_id = PluginId::parse("demo-plugin@test-marketplace").expect("plugin id");
-        let sources = load_plugin_hooks(&plugin_root, &plugin_id, &manifest.paths);
-
-        assert_eq!(sources.len(), 1);
-        assert_eq!(sources[0].source_relative_path, "plugin.json#hooks[0]");
-        assert_eq!(sources[0].hooks.handler_count(), 1);
-    }
-
-    #[test]
-    fn materialize_git_subdir_uses_sparse_checkout() {
-        let codex_home = tempfile::tempdir().expect("create codex home");
-        let repo = tempfile::tempdir().expect("create git repo");
-        let plugin_dir = repo.path().join("plugins/toolkit");
-        fs::create_dir_all(&plugin_dir).expect("create plugin directory");
-        fs::create_dir_all(repo.path().join("plugins/other")).expect("create other plugin");
-        fs::write(plugin_dir.join("marker.txt"), "toolkit").expect("write plugin marker");
-        fs::write(repo.path().join("plugins/other/marker.txt"), "other")
-            .expect("write other marker");
-        fs::write(repo.path().join("root.txt"), "root").expect("write root marker");
-
-        run_git(&["init"], Some(repo.path())).expect("init git repo");
-        run_git(
-            &["config", "user.email", "test@example.com"],
-            Some(repo.path()),
-        )
-        .expect("configure git email");
-        run_git(&["config", "user.name", "Test User"], Some(repo.path()))
-            .expect("configure git name");
-        run_git(&["add", "."], Some(repo.path())).expect("stage git repo");
-        run_git(&["commit", "-m", "init"], Some(repo.path())).expect("commit git repo");
-
-        let materialized = materialize_marketplace_plugin_source(
-            codex_home.path(),
-            &MarketplacePluginSource::Git {
-                url: repo.path().display().to_string(),
-                path: Some("plugins/toolkit".to_string()),
-                ref_name: None,
-                sha: None,
-            },
-        )
-        .expect("materialize git source");
-
-        assert_eq!(
-            plugin_dir.file_name(),
-            materialized.path.as_path().file_name()
-        );
-        assert!(materialized.path.as_path().join("marker.txt").is_file());
-        let checkout_root = materialized
-            .path
-            .as_path()
-            .parent()
-            .and_then(Path::parent)
-            .expect("materialized path should be nested under checkout root");
-        assert!(!checkout_root.join("root.txt").exists());
-        assert!(!checkout_root.join("plugins/other/marker.txt").exists());
-    }
-}
+#[path = "loader_tests.rs"]
+mod tests;
diff --git a/codex-rs/core-plugins/src/loader_tests.rs b/codex-rs/core-plugins/src/loader_tests.rs
new file mode 100644
index 0000000000..92ac416069
--- /dev/null
+++ b/codex-rs/core-plugins/src/loader_tests.rs
@@ -0,0 +1,347 @@
+use super::*;
+use crate::manifest::load_plugin_manifest;
+use codex_plugin::PluginId;
+use pretty_assertions::assert_eq;
+
+#[test]
+fn plugin_mcp_file_supports_mcp_servers_object_format() {
+    let parsed = serde_json::from_str::<PluginMcpFile>(
+        r#"{
+  "mcpServers": {
+    "sample": {
+      "command": "sample-mcp"
+    }
+  }
+}"#,
+    )
+    .expect("parse wrapped plugin mcp config")
+    .into_mcp_servers();
+
+    assert_eq!(
+        parsed,
+        HashMap::from([(
+            "sample".to_string(),
+            serde_json::json!({
+                "command": "sample-mcp"
+            }),
+        )])
+    );
+}
+
+#[test]
+fn plugin_mcp_file_supports_mcp_servers_object_format_with_metadata() {
+    let parsed = serde_json::from_str::<PluginMcpFile>(
+        r#"{
+  "$schema": "https://example.com/plugin-mcp.schema.json",
+  "mcpServers": {
+    "sample": {
+      "command": "sample-mcp"
+    }
+  }
+}"#,
+    )
+    .expect("parse plugin mcp config with metadata")
+    .into_mcp_servers();
+
+    assert_eq!(
+        parsed,
+        HashMap::from([(
+            "sample".to_string(),
+            serde_json::json!({
+                "command": "sample-mcp"
+            }),
+        )])
+    );
+}
+
+#[test]
+fn plugin_mcp_file_supports_top_level_server_map_format() {
+    let parsed = serde_json::from_str::<PluginMcpFile>(
+        r#"{
+  "linear": {
+    "type": "http",
+    "url": "https://mcp.linear.app/mcp"
+  }
+}"#,
+    )
+    .expect("parse flat plugin mcp config")
+    .into_mcp_servers();
+
+    assert_eq!(
+        parsed,
+        HashMap::from([(
+            "linear".to_string(),
+            serde_json::json!({
+                "type": "http",
+                "url": "https://mcp.linear.app/mcp"
+            }),
+        )])
+    );
+}
+
+#[test]
+fn curated_plugin_cache_version_shortens_full_git_sha() {
+    assert_eq!(
+        curated_plugin_cache_version("0123456789abcdef0123456789abcdef01234567"),
+        "01234567"
+    );
+}
+
+#[test]
+fn curated_plugin_cache_version_preserves_non_git_sha_versions() {
+    assert_eq!(
+        curated_plugin_cache_version("export-backup"),
+        "export-backup"
+    );
+    assert_eq!(curated_plugin_cache_version("0123456"), "0123456");
+}
+
+fn plugin_id() -> PluginId {
+    PluginId::parse("demo-plugin@test-marketplace").expect("plugin id")
+}
+
+fn plugin_root() -> (tempfile::TempDir, AbsolutePathBuf) {
+    let tmp = tempfile::tempdir().expect("tempdir");
+    let plugin_root =
+        AbsolutePathBuf::try_from(tmp.path().join("demo-plugin")).expect("plugin root");
+    fs::create_dir_all(plugin_root.join(".codex-plugin")).expect("create manifest dir");
+    fs::create_dir_all(plugin_root.join("hooks")).expect("create hooks dir");
+    (tmp, plugin_root)
+}
+
+fn write_manifest(plugin_root: &AbsolutePathBuf, manifest: &str) {
+    fs::write(plugin_root.join(".codex-plugin/plugin.json"), manifest).expect("write manifest");
+}
+
+fn write_hook_file(plugin_root: &AbsolutePathBuf, relative_path: &str, event: &str, command: &str) {
+    fs::write(
+        plugin_root.join(relative_path),
+        format!(
+            r#"{{
+  "hooks": {{
+    "{event}": [
+      {{
+        "hooks": [{{ "type": "command", "command": "{command}" }}]
+      }}
+    ]
+  }}
+}}"#
+        ),
+    )
+    .expect("write hooks");
+}
+
+fn load_sources(plugin_root: &AbsolutePathBuf) -> Vec<PluginHookSource> {
+    let manifest = load_plugin_manifest(plugin_root.as_path()).expect("manifest");
+    load_plugin_hooks(plugin_root, &plugin_id(), &manifest.paths)
+}
+
+#[test]
+fn load_plugin_hooks_discovers_default_hooks_file() {
+    let (_tmp, plugin_root) = plugin_root();
+    write_manifest(&plugin_root, r#"{ "name": "demo-plugin" }"#);
+    fs::write(
+        plugin_root.join("hooks/hooks.json"),
+        r#"{
+  "hooks": {
+    "PreToolUse": [
+      {
+        "matcher": "Bash",
+        "hooks": [{ "type": "command", "command": "echo default" }]
+      }
+    ]
+  }
+}"#,
+    )
+    .expect("write hooks");
+
+    let sources = load_sources(&plugin_root);
+
+    assert_eq!(sources.len(), 1);
+    assert_eq!(sources[0].plugin_id, plugin_id());
+    assert_eq!(sources[0].source_relative_path, "hooks/hooks.json");
+    assert_eq!(sources[0].hooks.handler_count(), 1);
+}
+
+#[test]
+fn load_plugin_hooks_supports_manifest_hook_path() {
+    let (_tmp, plugin_root) = plugin_root();
+    write_manifest(
+        &plugin_root,
+        r#"{
+  "name": "demo-plugin",
+  "hooks": "./hooks/one.json"
+}"#,
+    );
+    write_hook_file(&plugin_root, "hooks/one.json", "PreToolUse", "echo one");
+
+    let sources = load_sources(&plugin_root);
+
+    assert_eq!(
+        sources
+            .iter()
+            .map(|source| source.source_relative_path.as_str())
+            .collect::<Vec<_>>(),
+        vec!["hooks/one.json"]
+    );
+    assert_eq!(sources[0].hooks.handler_count(), 1);
+}
+
+#[test]
+fn load_plugin_hooks_manifest_paths_replace_default_hooks_file() {
+    let (_tmp, plugin_root) = plugin_root();
+    write_manifest(
+        &plugin_root,
+        r#"{
+  "name": "demo-plugin",
+  "hooks": ["./hooks/one.json", "./hooks/two.json"]
+}"#,
+    );
+    write_hook_file(
+        &plugin_root,
+        "hooks/hooks.json",
+        "PreToolUse",
+        "echo ignored",
+    );
+    write_hook_file(&plugin_root, "hooks/one.json", "PreToolUse", "echo one");
+    write_hook_file(&plugin_root, "hooks/two.json", "PostToolUse", "echo two");
+
+    let sources = load_sources(&plugin_root);
+
+    assert_eq!(
+        sources
+            .iter()
+            .map(|source| source.source_relative_path.as_str())
+            .collect::<Vec<_>>(),
+        vec!["hooks/one.json", "hooks/two.json"]
+    );
+    assert_eq!(
+        sources
+            .iter()
+            .map(|source| source.hooks.handler_count())
+            .collect::<Vec<_>>(),
+        vec![1, 1]
+    );
+}
+
+#[test]
+fn load_plugin_hooks_supports_inline_manifest_hooks() {
+    let (_tmp, plugin_root) = plugin_root();
+    write_manifest(
+        &plugin_root,
+        r#"{
+  "name": "demo-plugin",
+  "hooks": {
+    "hooks": {
+      "SessionStart": [
+        {
+          "matcher": "startup",
+          "hooks": [{ "type": "command", "command": "echo inline" }]
+        }
+      ]
+    }
+  }
+}"#,
+    );
+
+    let sources = load_sources(&plugin_root);
+
+    assert_eq!(sources.len(), 1);
+    assert_eq!(sources[0].source_relative_path, "plugin.json#hooks[0]");
+    assert_eq!(sources[0].hooks.handler_count(), 1);
+}
+
+#[test]
+fn load_plugin_hooks_supports_inline_manifest_hook_list() {
+    let (_tmp, plugin_root) = plugin_root();
+    write_manifest(
+        &plugin_root,
+        r#"{
+  "name": "demo-plugin",
+  "hooks": [
+    {
+      "hooks": {
+        "SessionStart": [
+          {
+            "hooks": [{ "type": "command", "command": "echo inline one" }]
+          }
+        ]
+      }
+    },
+    {
+      "hooks": {
+        "Stop": [
+          {
+            "hooks": [{ "type": "command", "command": "echo inline two" }]
+          }
+        ]
+      }
+    }
+  ]
+}"#,
+    );
+
+    let sources = load_sources(&plugin_root);
+
+    assert_eq!(
+        sources
+            .iter()
+            .map(|source| source.source_relative_path.as_str())
+            .collect::<Vec<_>>(),
+        vec!["plugin.json#hooks[0]", "plugin.json#hooks[1]"]
+    );
+    assert_eq!(
+        sources
+            .iter()
+            .map(|source| source.hooks.handler_count())
+            .collect::<Vec<_>>(),
+        vec![1, 1]
+    );
+}
+
+#[test]
+fn materialize_git_subdir_uses_sparse_checkout() {
+    let codex_home = tempfile::tempdir().expect("create codex home");
+    let repo = tempfile::tempdir().expect("create git repo");
+    let plugin_dir = repo.path().join("plugins/toolkit");
+    fs::create_dir_all(&plugin_dir).expect("create plugin directory");
+    fs::create_dir_all(repo.path().join("plugins/other")).expect("create other plugin");
+    fs::write(plugin_dir.join("marker.txt"), "toolkit").expect("write plugin marker");
+    fs::write(repo.path().join("plugins/other/marker.txt"), "other").expect("write other marker");
+    fs::write(repo.path().join("root.txt"), "root").expect("write root marker");
+
+    run_git(&["init"], Some(repo.path())).expect("init git repo");
+    run_git(
+        &["config", "user.email", "test@example.com"],
+        Some(repo.path()),
+    )
+    .expect("configure git email");
+    run_git(&["config", "user.name", "Test User"], Some(repo.path())).expect("configure git name");
+    run_git(&["add", "."], Some(repo.path())).expect("stage git repo");
+    run_git(&["commit", "-m", "init"], Some(repo.path())).expect("commit git repo");
+
+    let materialized = materialize_marketplace_plugin_source(
+        codex_home.path(),
+        &MarketplacePluginSource::Git {
+            url: repo.path().display().to_string(),
+            path: Some("plugins/toolkit".to_string()),
+            ref_name: None,
+            sha: None,
+        },
+    )
+    .expect("materialize git source");
+
+    assert_eq!(
+        plugin_dir.file_name(),
+        materialized.path.as_path().file_name()
+    );
+    assert!(materialized.path.as_path().join("marker.txt").is_file());
+    let checkout_root = materialized
+        .path
+        .as_path()
+        .parent()
+        .and_then(Path::parent)
+        .expect("materialized path should be nested under checkout root");
+    assert!(!checkout_root.join("root.txt").exists());
+    assert!(!checkout_root.join("plugins/other/marker.txt").exists());
+}