diff --git a/crates/forge_main/src/banner.rs b/crates/forge_main/src/banner.rs
index 1827ddaa52..6842fae8a7 100644
--- a/crates/forge_main/src/banner.rs
+++ b/crates/forge_main/src/banner.rs
@@ -105,14 +105,21 @@ pub fn display(cli_mode: bool) -> io::Result<()> {
 
     println!("{banner}\n");
 
-    // Encourage zsh integration after the banner
-    if !cli_mode {
+    if !cli_mode && !is_zsh_plugin_loaded() {
         display_zsh_encouragement();
     }
 
     Ok(())
 }
 
+/// Returns `true` when the zsh plugin exported `_FORGE_PLUGIN_LOADED` into the
+/// environment inherited by this forge process.
+fn is_zsh_plugin_loaded() -> bool {
+    std::env::var("_FORGE_PLUGIN_LOADED")
+        .map(|v| !v.is_empty())
+        .unwrap_or(false)
+}
+
 /// Encourages users to use the zsh plugin for a better experience.
 fn display_zsh_encouragement() {
     let tip = DisplayBox::new(vec![
@@ -136,3 +143,65 @@ fn display_zsh_encouragement() {
     ]);
     println!("{}", tip);
 }
+
+#[cfg(test)]
+mod tests {
+    use std::env;
+    use std::ffi::OsString;
+    use std::sync::{LazyLock, Mutex, MutexGuard};
+
+    use super::*;
+
+    static ENV_MUTEX: LazyLock<Mutex<()>> = LazyLock::new(|| Mutex::new(()));
+
+    struct EnvGuard {
+        key: &'static str,
+        original_value: Option<OsString>,
+        _lock: MutexGuard<'static, ()>,
+    }
+
+    impl EnvGuard {
+        fn set(key: &'static str, value: &str) -> Self {
+            let lock = ENV_MUTEX.lock().unwrap_or_else(|error| error.into_inner());
+            let original_value = env::var_os(key);
+            unsafe {
+                env::set_var(key, value);
+            }
+            Self { key, original_value, _lock: lock }
+        }
+
+        fn unset(key: &'static str) -> Self {
+            let lock = ENV_MUTEX.lock().unwrap_or_else(|error| error.into_inner());
+            let original_value = env::var_os(key);
+            unsafe {
+                env::remove_var(key);
+            }
+            Self { key, original_value, _lock: lock }
+        }
+    }
+
+    impl Drop for EnvGuard {
+        fn drop(&mut self) {
+            match &self.original_value {
+                Some(value) => unsafe {
+                    env::set_var(self.key, value);
+                },
+                None => unsafe {
+                    env::remove_var(self.key);
+                },
+            }
+        }
+    }
+
+    #[test]
+    fn test_is_zsh_plugin_loaded_when_env_var_set() {
+        let _guard = EnvGuard::set("_FORGE_PLUGIN_LOADED", "1700000000");
+        assert!(is_zsh_plugin_loaded());
+    }
+
+    #[test]
+    fn test_is_zsh_plugin_loaded_when_env_var_missing() {
+        let _guard = EnvGuard::unset("_FORGE_PLUGIN_LOADED");
+        assert!(!is_zsh_plugin_loaded());
+    }
+}
diff --git a/crates/forge_main/src/zsh/plugin.rs b/crates/forge_main/src/zsh/plugin.rs
index 5e96121952..1dd04388b8 100644
--- a/crates/forge_main/src/zsh/plugin.rs
+++ b/crates/forge_main/src/zsh/plugin.rs
@@ -43,8 +43,8 @@ pub fn generate_zsh_plugin() -> Result<String> {
     output.push_str("\n# --- Clap Completions ---\n");
     output.push_str(&completions_str);
 
-    // Set environment variable to indicate plugin is loaded (with timestamp)
-    output.push_str("\n_FORGE_PLUGIN_LOADED=$(date +%s)\n");
+    // Exported so child `forge` processes can detect an active plugin.
+    output.push_str("\nexport _FORGE_PLUGIN_LOADED=$(date +%s)\n");
 
     Ok(output)
 }
@@ -54,8 +54,8 @@ pub fn generate_zsh_theme() -> Result<String> {
     let mut content =
         super::normalize_script(include_str!("../../../../shell-plugin/forge.theme.zsh"));
 
-    // Set environment variable to indicate theme is loaded (with timestamp)
-    content.push_str("\n_FORGE_THEME_LOADED=$(date +%s)\n");
+    // Exported so child `forge` processes can detect an active theme.
+    content.push_str("\nexport _FORGE_THEME_LOADED=$(date +%s)\n");
 
     Ok(content)
 }