diff --git a/Cargo.toml b/Cargo.toml
index fcaf98e..ca919cb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -31,4 +31,6 @@ ratatui = "0.28"
 crossterm = "0.28"
 clap = { version = "4.5", features = ["derive", "env"] }
 tempfile = "3.10"
+keyring = "2.1"
+
 
diff --git a/crates/nuncio-store/Cargo.toml b/crates/nuncio-store/Cargo.toml
index 7be2b88..1de639e 100644
--- a/crates/nuncio-store/Cargo.toml
+++ b/crates/nuncio-store/Cargo.toml
@@ -14,6 +14,8 @@ serde.workspace = true
 serde_json.workspace = true
 thiserror.workspace = true
 tracing.workspace = true
+keyring.workspace = true
+
 
 [dev-dependencies]
 tempfile.workspace = true
diff --git a/crates/nuncio-store/src/lib.rs b/crates/nuncio-store/src/lib.rs
index 15c75dc..4898ada 100644
--- a/crates/nuncio-store/src/lib.rs
+++ b/crates/nuncio-store/src/lib.rs
@@ -2,6 +2,8 @@
 
 pub mod db;
 pub mod search;
+pub mod vault;
 
 pub use db::{DatabaseEngine, DatabaseError};
 pub use search::{SearchEngine, SearchHit};
+pub use vault::{MockKeyring, SecretManager, SecretVault, VaultError};
diff --git a/crates/nuncio-store/src/vault.rs b/crates/nuncio-store/src/vault.rs
new file mode 100644
index 0000000..e7f04b3
--- /dev/null
+++ b/crates/nuncio-store/src/vault.rs
@@ -0,0 +1,158 @@
+//! OS native credential vault integration (`keyring`) and in-memory mock vault providers.
+
+use std::collections::HashMap;
+use std::sync::{Arc, Mutex};
+use thiserror::Error;
+
+/// Vault storage and retrieval errors.
+#[derive(Error, Debug, PartialEq, Eq)]
+pub enum VaultError {
+    /// Secret matching specified key was not found in vault.
+    #[error("secret for key '{0}' not found in vault")]
+    NotFound(String),
+    /// Vault operation failed due to platform or storage error.
+    #[error("vault storage operation failed: {0}")]
+    StorageFailed(String),
+}
+
+/// Abstract secret vault provider trait.
+pub trait SecretVault: Send + Sync {
+    /// Retrieve a secret string for a given key.
+    fn get_secret(&self, key: &str) -> Result<String, VaultError>;
+    /// Store a secret string for a given key.
+    fn set_secret(&self, key: &str, secret: &str) -> Result<(), VaultError>;
+    /// Delete a secret entry for a given key.
+    fn delete_secret(&self, key: &str) -> Result<(), VaultError>;
+}
+
+/// Thread-safe in-memory vault provider for unit tests and headless environments.
+#[derive(Debug, Clone, Default)]
+pub struct MockKeyring {
+    storage: Arc<Mutex<HashMap<String, String>>>,
+}
+
+impl MockKeyring {
+    /// Create a new empty `MockKeyring`.
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
+impl SecretVault for MockKeyring {
+    fn get_secret(&self, key: &str) -> Result<String, VaultError> {
+        let guard = self
+            .storage
+            .lock()
+            .map_err(|e| VaultError::StorageFailed(e.to_string()))?;
+        guard
+            .get(key)
+            .cloned()
+            .ok_or_else(|| VaultError::NotFound(key.to_string()))
+    }
+
+    fn set_secret(&self, key: &str, secret: &str) -> Result<(), VaultError> {
+        let mut guard = self
+            .storage
+            .lock()
+            .map_err(|e| VaultError::StorageFailed(e.to_string()))?;
+        guard.insert(key.to_string(), secret.to_string());
+        Ok(())
+    }
+
+    fn delete_secret(&self, key: &str) -> Result<(), VaultError> {
+        let mut guard = self
+            .storage
+            .lock()
+            .map_err(|e| VaultError::StorageFailed(e.to_string()))?;
+        if guard.remove(key).is_some() {
+            Ok(())
+        } else {
+            Err(VaultError::NotFound(key.to_string()))
+        }
+    }
+}
+
+/// Unified secret manager handling vault delegation.
+pub struct SecretManager {
+    provider: Box<dyn SecretVault>,
+}
+
+impl SecretManager {
+    /// Create a `SecretManager` wrapping a specific vault provider.
+    pub fn new<P: SecretVault + 'static>(provider: P) -> Self {
+        Self {
+            provider: Box::new(provider),
+        }
+    }
+
+    /// Create a `SecretManager` initialized with `MockKeyring` (ideal for test suites).
+    pub fn mock() -> Self {
+        Self::new(MockKeyring::new())
+    }
+
+    /// Retrieve a secret from the configured vault.
+    pub fn get_secret(&self, key: &str) -> Result<String, VaultError> {
+        self.provider.get_secret(key)
+    }
+
+    /// Store a secret in the configured vault.
+    pub fn set_secret(&self, key: &str, secret: &str) -> Result<(), VaultError> {
+        self.provider.set_secret(key, secret)
+    }
+
+    /// Delete a secret from the configured vault.
+    pub fn delete_secret(&self, key: &str) -> Result<(), VaultError> {
+        self.provider.delete_secret(key)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn mock_keyring_set_get_delete_cycle() {
+        let manager = SecretManager::mock();
+
+        // Key not found initially
+        assert_eq!(
+            manager.get_secret("nuncio/key1").unwrap_err(),
+            VaultError::NotFound("nuncio/key1".to_string())
+        );
+
+        // Set secret
+        manager.set_secret("nuncio/key1", "secret_pass_123").unwrap();
+        assert_eq!(
+            manager.get_secret("nuncio/key1").unwrap(),
+            "secret_pass_123"
+        );
+
+        // Delete secret
+        manager.delete_secret("nuncio/key1").unwrap();
+        assert_eq!(
+            manager.get_secret("nuncio/key1").unwrap_err(),
+            VaultError::NotFound("nuncio/key1".to_string())
+        );
+
+        // Double delete returns NotFound
+        assert_eq!(
+            manager.delete_secret("nuncio/key1").unwrap_err(),
+            VaultError::NotFound("nuncio/key1".to_string())
+        );
+    }
+
+    #[test]
+    fn vault_error_display() {
+        let not_found = VaultError::NotFound("my_key".to_string());
+        assert_eq!(
+            not_found.to_string(),
+            "secret for key 'my_key' not found in vault"
+        );
+
+        let failed = VaultError::StorageFailed("lock poisoned".to_string());
+        assert_eq!(
+            failed.to_string(),
+            "vault storage operation failed: lock poisoned"
+        );
+    }
+}