diff --git a/crates/csa-config/src/config.rs b/crates/csa-config/src/config.rs
index bb9b6c7..f2452a6 100644
--- a/crates/csa-config/src/config.rs
+++ b/crates/csa-config/src/config.rs
@@ -169,8 +169,8 @@ fn merge_toml_values(base: toml::Value, overlay: toml::Value) -> toml::Value {
 impl ProjectConfig {
     /// Load config with fallback chain:
     ///
-    /// 1. If both `.csa/config.toml` (project) and `~/.config/csa/config.toml` (user) exist,
-    ///    deep-merge them with project settings overriding user settings.
+    /// 1. If both `.csa/config.toml` (project) and `~/.config/cli-sub-agent/config.toml` (user)
+    ///    exist, deep-merge them with project settings overriding user settings.
     /// 2. If only project config exists, use it directly.
     /// 3. If only user config exists, use it as fallback.
     /// 4. If neither exists, return None.
@@ -267,12 +267,12 @@ impl ProjectConfig {
         Ok(Some(config))
     }
 
-    /// Path to user-level config: `~/.config/csa/config.toml`.
+    /// Path to user-level config: `~/.config/cli-sub-agent/config.toml`.
     ///
     /// Returns None if the config directory cannot be determined
     /// (e.g., no HOME in containers).
     pub fn user_config_path() -> Option<PathBuf> {
-        directories::ProjectDirs::from("", "", "csa")
+        directories::ProjectDirs::from("", "", "cli-sub-agent")
             .map(|dirs| dirs.config_dir().join("config.toml"))
     }
 
@@ -374,7 +374,7 @@ impl ProjectConfig {
             .unwrap_or(false)
     }
 
-    /// Save a user-level config template to `~/.config/csa/config.toml`.
+    /// Save a user-level config template to `~/.config/cli-sub-agent/config.toml`.
     ///
     /// Creates the directory if needed. Returns the path written, or None
     /// if the config directory cannot be determined.
@@ -396,7 +396,7 @@ impl ProjectConfig {
     /// Generate a commented template for user-level config.
     pub fn user_config_template() -> String {
         r#"# CSA User-Level Configuration
-# Location: ~/.config/csa/config.toml
+# Location: ~/.config/cli-sub-agent/config.toml
 #
 # This file provides default tiers, tool settings, and aliases
 # that apply across all CSA projects unless overridden by
diff --git a/crates/csa-config/src/config_merge_tests.rs b/crates/csa-config/src/config_merge_tests.rs
index f59e62f..92b572f 100644
--- a/crates/csa-config/src/config_merge_tests.rs
+++ b/crates/csa-config/src/config_merge_tests.rs
@@ -188,7 +188,7 @@ fn test_user_config_path_returns_some() {
     if std::env::var("HOME").is_ok() {
         assert!(path.is_some());
         let p = path.unwrap();
-        assert!(p.to_string_lossy().contains("csa"));
+        assert!(p.to_string_lossy().contains("cli-sub-agent"));
         assert!(p.to_string_lossy().contains("config.toml"));
     }
     // In containers without HOME, it's OK to return None
@@ -202,4 +202,88 @@ fn test_user_config_template_is_valid() {
     assert!(template.contains("[resources]"));
     assert!(template.contains("suppress_notify"));
     assert!(template.contains("# [tiers."));
+    // Template location comment should point to unified path
+    assert!(template.contains("cli-sub-agent/config.toml"));
+}
+
+#[test]
+fn test_user_config_path_matches_global_config_dir() {
+    // After unification, user-level ProjectConfig and GlobalConfig share the same directory.
+    if std::env::var("HOME").is_err() {
+        return; // Skip in containers
+    }
+    let user_path = ProjectConfig::user_config_path().unwrap();
+    let global_path = crate::GlobalConfig::config_path().unwrap();
+    assert_eq!(
+        user_path.parent(),
+        global_path.parent(),
+        "User and global config should share the same directory"
+    );
+}
+
+#[test]
+fn test_load_user_tiers_without_project_config() {
+    // When only user-level config exists (no project config),
+    // load should return user-level tiers.
+    let tmp = tempfile::tempdir().unwrap();
+    let user_path = tmp.path().join("user.toml");
+    let project_path = tmp
+        .path()
+        .join("nonexistent")
+        .join(".csa")
+        .join("config.toml");
+
+    std::fs::write(
+        &user_path,
+        r#"
+schema_version = 1
+[tiers.user-tier]
+description = "User-level tier"
+models = ["codex/openai/o3/medium"]
+"#,
+    )
+    .unwrap();
+
+    let config = ProjectConfig::load_with_paths(Some(&user_path), &project_path)
+        .unwrap()
+        .expect("Should load from user path");
+    assert!(config.tiers.contains_key("user-tier"));
+}
+
+#[test]
+fn test_load_project_overrides_user_tiers() {
+    // When both user and project configs exist, project tiers
+    // override user tiers (deep merge).
+    let tmp = tempfile::tempdir().unwrap();
+    let user_path = tmp.path().join("user.toml");
+    let project_path = tmp.path().join("project.toml");
+
+    std::fs::write(
+        &user_path,
+        r#"
+schema_version = 1
+[tiers.shared-tier]
+description = "User version"
+models = ["codex/openai/o3/medium"]
+"#,
+    )
+    .unwrap();
+
+    std::fs::write(
+        &project_path,
+        r#"
+schema_version = 1
+[tiers.shared-tier]
+description = "Project version"
+models = ["codex/openai/o3/high"]
+"#,
+    )
+    .unwrap();
+
+    let config = ProjectConfig::load_with_paths(Some(&user_path), &project_path)
+        .unwrap()
+        .expect("Should load merged config");
+    let tier = config.tiers.get("shared-tier").unwrap();
+    assert_eq!(tier.description, "Project version");
+    assert_eq!(tier.models, vec!["codex/openai/o3/high"]);
 }
diff --git a/crates/csa-config/src/config_tests.rs b/crates/csa-config/src/config_tests.rs
index d9d8c15..0dca5b3 100644
--- a/crates/csa-config/src/config_tests.rs
+++ b/crates/csa-config/src/config_tests.rs
@@ -4,7 +4,7 @@ use tempfile::tempdir;
 #[test]
 fn test_load_nonexistent_returns_none() {
     let dir = tempdir().unwrap();
-    // Use load_with_paths to isolate from real ~/.config/csa/config.toml on host.
+    // Use load_with_paths to isolate from real ~/.config/cli-sub-agent/config.toml on host.
     let project_path = dir.path().join(".csa").join("config.toml");
     let result = ProjectConfig::load_with_paths(None, &project_path).unwrap();
     assert!(result.is_none());
diff --git a/skills/install-update-csa/SKILL.md b/skills/install-update-csa/SKILL.md
index 05f1eb1..140b251 100644
--- a/skills/install-update-csa/SKILL.md
+++ b/skills/install-update-csa/SKILL.md
@@ -21,7 +21,7 @@ capability tiers, and sets tool-specific restrictions.
 
 - First time installing or setting up CSA
 - Updating CSA binary to a new version
-- Checking or creating global user config (`~/.config/csa/config.toml`)
+- Checking or creating global user config (`~/.config/cli-sub-agent/config.toml`)
 - First time setting up CSA in a project (project-level config)
 - Reconfiguring tool/model selection for changed requirements
 - Adding newly installed tools or models
@@ -29,7 +29,7 @@ capability tiers, and sets tool-specific restrictions.
 ## Output
 
 - CSA binary verified in PATH
-- `~/.config/csa/config.toml` — global user configuration (TOML)
+- `~/.config/cli-sub-agent/config.toml` — global user configuration (TOML)
 - `.csa/config.toml` — project configuration (TOML)
 - `.csa/` added to `.gitignore`
 
@@ -63,10 +63,10 @@ Report the version. If it looks outdated, suggest updating.
 
 ### Phase 0.5: Check Global Config
 
-Check if the global user config exists at `~/.config/csa/config.toml`:
+Check if the global user config exists at `~/.config/cli-sub-agent/config.toml`:
 
 ```bash
-ls ~/.config/csa/config.toml 2>/dev/null
+ls ~/.config/cli-sub-agent/config.toml 2>/dev/null
 ```
 
 - If **not found**:
@@ -81,7 +81,7 @@ ls ~/.config/csa/config.toml 2>/dev/null
 
 **Key settings to include in global config**:
 ```toml
-# ~/.config/csa/config.toml
+# ~/.config/cli-sub-agent/config.toml
 # Global defaults — project configs override these values.
 
 [tools.codex]