feat: add Composio tool provider + encrypted secret store + wizard integration

- src/tools/composio.rs: ComposioTool implementing Tool trait
  - list/execute/connect actions via Composio API (1000+ OAuth apps)
  - 60s timeout, proper error handling, JSON schema for LLM
  - 12 tests covering schema, validation, serde, error paths

- src/security/secrets.rs: SecretStore for encrypted credential storage
  - XOR cipher with random 32-byte key stored in ~/.zeroclaw/.secret_key
  - enc: prefix for encrypted values, plaintext passthrough (backward compat)
  - Key file created with 0600 permissions (Unix)
  - 16 tests: roundtrip, unicode, long secrets, corrupt hex, permissions

- src/config/schema.rs: ComposioConfig + SecretsConfig structs
  - Composio: enabled (default: false), api_key, entity_id
  - Secrets: encrypt (default: true)
  - Both with serde(default) for backward compatibility
  - 8 new config tests

- src/onboard/wizard.rs: new Step 5 'Tool Mode & Security'
  - Sovereign (local only) vs Composio (managed OAuth) selection
  - Encrypted secret storage toggle (default: on)
  - 7-step wizard (was 6)

- src/tools/mod.rs: all_tools() now accepts optional composio_key
- src/agent/loop_.rs: wires Composio key from config into tool registry
- README.md: Composio integration + encrypted secrets documentation

1017 tests, 0 clippy warnings, cargo fmt clean.

src/security/secrets.rs

@@ -0,0 +1,338 @@
+// Encrypted secret store — defense-in-depth for API keys and tokens.
+//
+// Secrets are encrypted using a random key stored in `~/.zeroclaw/.secret_key`
+// with restrictive file permissions (0600). The config file stores only
+// hex-encoded ciphertext, never plaintext keys.
+//
+// This prevents:
+//   - Plaintext exposure in config files
+//   - Casual `grep` or `git log` leaks
+//   - Accidental commit of raw API keys
+//
+// For sovereign users who prefer plaintext, `secrets.encrypt = false` disables this.
+
+use anyhow::{Context, Result};
+use std::fs;
+use std::path::{Path, PathBuf};
+
+/// Length of the random encryption key in bytes.
+const KEY_LEN: usize = 32;
+
+/// Manages encrypted storage of secrets (API keys, tokens, etc.)
+#[derive(Debug, Clone)]
+pub struct SecretStore {
+    /// Path to the key file (`~/.zeroclaw/.secret_key`)
+    key_path: PathBuf,
+    /// Whether encryption is enabled
+    enabled: bool,
+}
+
+impl SecretStore {
+    /// Create a new secret store rooted at the given directory.
+    pub fn new(zeroclaw_dir: &Path, enabled: bool) -> Self {
+        Self {
+            key_path: zeroclaw_dir.join(".secret_key"),
+            enabled,
+        }
+    }
+
+    /// Encrypt a plaintext secret. Returns hex-encoded ciphertext prefixed with `enc:`.
+    /// If encryption is disabled, returns the plaintext as-is.
+    pub fn encrypt(&self, plaintext: &str) -> Result<String> {
+        if !self.enabled || plaintext.is_empty() {
+            return Ok(plaintext.to_string());
+        }
+
+        let key = self.load_or_create_key()?;
+        let ciphertext = xor_cipher(plaintext.as_bytes(), &key);
+        Ok(format!("enc:{}", hex_encode(&ciphertext)))
+    }
+
+    /// Decrypt a secret. If the value starts with `enc:`, it's decrypted.
+    /// Otherwise, it's returned as-is (backward-compatible with plaintext configs).
+    pub fn decrypt(&self, value: &str) -> Result<String> {
+        if !value.starts_with("enc:") {
+            return Ok(value.to_string());
+        }
+
+        let hex_str = &value[4..]; // strip "enc:" prefix
+        let ciphertext =
+            hex_decode(hex_str).context("Failed to decode encrypted secret (corrupt hex)")?;
+        let key = self.load_or_create_key()?;
+        let plaintext_bytes = xor_cipher(&ciphertext, &key);
+        String::from_utf8(plaintext_bytes)
+            .context("Decrypted secret is not valid UTF-8 — wrong key or corrupt data")
+    }
+
+    /// Check if a value is already encrypted.
+    pub fn is_encrypted(value: &str) -> bool {
+        value.starts_with("enc:")
+    }
+
+    /// Load the encryption key from disk, or create one if it doesn't exist.
+    fn load_or_create_key(&self) -> Result<Vec<u8>> {
+        if self.key_path.exists() {
+            let hex_key =
+                fs::read_to_string(&self.key_path).context("Failed to read secret key file")?;
+            hex_decode(hex_key.trim()).context("Secret key file is corrupt")
+        } else {
+            let key = generate_random_key();
+            if let Some(parent) = self.key_path.parent() {
+                fs::create_dir_all(parent)?;
+            }
+            fs::write(&self.key_path, hex_encode(&key))
+                .context("Failed to write secret key file")?;
+
+            // Set restrictive permissions (Unix only)
+            #[cfg(unix)]
+            {
+                use std::os::unix::fs::PermissionsExt;
+                fs::set_permissions(&self.key_path, fs::Permissions::from_mode(0o600))
+                    .context("Failed to set key file permissions")?;
+            }
+
+            Ok(key)
+        }
+    }
+}
+
+/// XOR cipher with repeating key. Same function for encrypt and decrypt.
+fn xor_cipher(data: &[u8], key: &[u8]) -> Vec<u8> {
+    if key.is_empty() {
+        return data.to_vec();
+    }
+    data.iter()
+        .enumerate()
+        .map(|(i, &b)| b ^ key[i % key.len()])
+        .collect()
+}
+
+/// Generate a random key using system entropy (UUID v4 + process ID + timestamp).
+fn generate_random_key() -> Vec<u8> {
+    // Use two UUIDs (32 random bytes) as our key material
+    let u1 = uuid::Uuid::new_v4();
+    let u2 = uuid::Uuid::new_v4();
+    let mut key = Vec::with_capacity(KEY_LEN);
+    key.extend_from_slice(u1.as_bytes());
+    key.extend_from_slice(u2.as_bytes());
+    key.truncate(KEY_LEN);
+    key
+}
+
+/// Hex-encode bytes to a lowercase hex string.
+fn hex_encode(data: &[u8]) -> String {
+    let mut s = String::with_capacity(data.len() * 2);
+    for b in data {
+        use std::fmt::Write;
+        let _ = write!(s, "{b:02x}");
+    }
+    s
+}
+
+/// Hex-decode a hex string to bytes.
+fn hex_decode(hex: &str) -> Result<Vec<u8>> {
+    if !hex.len().is_multiple_of(2) {
+        anyhow::bail!("Hex string has odd length");
+    }
+    (0..hex.len())
+        .step_by(2)
+        .map(|i| {
+            u8::from_str_radix(&hex[i..i + 2], 16)
+                .map_err(|e| anyhow::anyhow!("Invalid hex at position {i}: {e}"))
+        })
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::TempDir;
+
+    // ── SecretStore basics ─────────────────────────────────────
+
+    #[test]
+    fn encrypt_decrypt_roundtrip() {
+        let tmp = TempDir::new().unwrap();
+        let store = SecretStore::new(tmp.path(), true);
+        let secret = "sk-my-secret-api-key-12345";
+
+        let encrypted = store.encrypt(secret).unwrap();
+        assert!(encrypted.starts_with("enc:"), "Should have enc: prefix");
+        assert_ne!(encrypted, secret, "Should not be plaintext");
+
+        let decrypted = store.decrypt(&encrypted).unwrap();
+        assert_eq!(decrypted, secret, "Roundtrip must preserve original");
+    }
+
+    #[test]
+    fn encrypt_empty_returns_empty() {
+        let tmp = TempDir::new().unwrap();
+        let store = SecretStore::new(tmp.path(), true);
+        let result = store.encrypt("").unwrap();
+        assert_eq!(result, "");
+    }
+
+    #[test]
+    fn decrypt_plaintext_passthrough() {
+        let tmp = TempDir::new().unwrap();
+        let store = SecretStore::new(tmp.path(), true);
+        // Values without "enc:" prefix are returned as-is (backward compat)
+        let result = store.decrypt("sk-plaintext-key").unwrap();
+        assert_eq!(result, "sk-plaintext-key");
+    }
+
+    #[test]
+    fn disabled_store_returns_plaintext() {
+        let tmp = TempDir::new().unwrap();
+        let store = SecretStore::new(tmp.path(), false);
+        let result = store.encrypt("sk-secret").unwrap();
+        assert_eq!(result, "sk-secret", "Disabled store should not encrypt");
+    }
+
+    #[test]
+    fn is_encrypted_detects_prefix() {
+        assert!(SecretStore::is_encrypted("enc:aabbcc"));
+        assert!(!SecretStore::is_encrypted("sk-plaintext"));
+        assert!(!SecretStore::is_encrypted(""));
+    }
+
+    #[test]
+    fn key_file_created_on_first_encrypt() {
+        let tmp = TempDir::new().unwrap();
+        let store = SecretStore::new(tmp.path(), true);
+        assert!(!store.key_path.exists());
+
+        store.encrypt("test").unwrap();
+        assert!(store.key_path.exists(), "Key file should be created");
+
+        let key_hex = fs::read_to_string(&store.key_path).unwrap();
+        assert_eq!(
+            key_hex.len(),
+            KEY_LEN * 2,
+            "Key should be {KEY_LEN} bytes hex-encoded"
+        );
+    }
+
+    #[test]
+    fn same_key_used_across_calls() {
+        let tmp = TempDir::new().unwrap();
+        let store = SecretStore::new(tmp.path(), true);
+
+        let e1 = store.encrypt("secret").unwrap();
+        let e2 = store.encrypt("secret").unwrap();
+        assert_eq!(e1, e2, "Same key should produce same ciphertext");
+    }
+
+    #[test]
+    fn different_stores_same_dir_interop() {
+        let tmp = TempDir::new().unwrap();
+        let store1 = SecretStore::new(tmp.path(), true);
+        let store2 = SecretStore::new(tmp.path(), true);
+
+        let encrypted = store1.encrypt("cross-store-secret").unwrap();
+        let decrypted = store2.decrypt(&encrypted).unwrap();
+        assert_eq!(decrypted, "cross-store-secret");
+    }
+
+    #[test]
+    fn unicode_secret_roundtrip() {
+        let tmp = TempDir::new().unwrap();
+        let store = SecretStore::new(tmp.path(), true);
+        let secret = "sk-日本語テスト-émojis-🦀";
+
+        let encrypted = store.encrypt(secret).unwrap();
+        let decrypted = store.decrypt(&encrypted).unwrap();
+        assert_eq!(decrypted, secret);
+    }
+
+    #[test]
+    fn long_secret_roundtrip() {
+        let tmp = TempDir::new().unwrap();
+        let store = SecretStore::new(tmp.path(), true);
+        let secret = "a".repeat(10_000);
+
+        let encrypted = store.encrypt(&secret).unwrap();
+        let decrypted = store.decrypt(&encrypted).unwrap();
+        assert_eq!(decrypted, secret);
+    }
+
+    #[test]
+    fn corrupt_hex_returns_error() {
+        let tmp = TempDir::new().unwrap();
+        let store = SecretStore::new(tmp.path(), true);
+        let result = store.decrypt("enc:not-valid-hex!!");
+        assert!(result.is_err());
+    }
+
+    // ── Low-level helpers ───────────────────────────────────────
+
+    #[test]
+    fn xor_cipher_roundtrip() {
+        let key = b"testkey123";
+        let data = b"hello world";
+        let encrypted = xor_cipher(data, key);
+        let decrypted = xor_cipher(&encrypted, key);
+        assert_eq!(decrypted, data);
+    }
+
+    #[test]
+    fn xor_cipher_empty_key() {
+        let data = b"passthrough";
+        let result = xor_cipher(data, &[]);
+        assert_eq!(result, data);
+    }
+
+    #[test]
+    fn hex_roundtrip() {
+        let data = vec![0x00, 0x01, 0xfe, 0xff, 0xab, 0xcd];
+        let encoded = hex_encode(&data);
+        assert_eq!(encoded, "0001feffabcd");
+        let decoded = hex_decode(&encoded).unwrap();
+        assert_eq!(decoded, data);
+    }
+
+    #[test]
+    fn hex_decode_odd_length_fails() {
+        assert!(hex_decode("abc").is_err());
+    }
+
+    #[test]
+    fn hex_decode_invalid_chars_fails() {
+        assert!(hex_decode("zzzz").is_err());
+    }
+
+    #[test]
+    fn generate_random_key_correct_length() {
+        let key = generate_random_key();
+        assert_eq!(key.len(), KEY_LEN);
+    }
+
+    #[test]
+    fn generate_random_key_not_all_zeros() {
+        let key = generate_random_key();
+        assert!(key.iter().any(|&b| b != 0), "Key should not be all zeros");
+    }
+
+    #[test]
+    fn two_random_keys_differ() {
+        let k1 = generate_random_key();
+        let k2 = generate_random_key();
+        assert_ne!(k1, k2, "Two random keys should differ");
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn key_file_has_restricted_permissions() {
+        use std::os::unix::fs::PermissionsExt;
+        let tmp = TempDir::new().unwrap();
+        let store = SecretStore::new(tmp.path(), true);
+        store.encrypt("trigger key creation").unwrap();
+
+        let perms = fs::metadata(&store.key_path).unwrap().permissions();
+        assert_eq!(
+            perms.mode() & 0o777,
+            0o600,
+            "Key file must be owner-only (0600)"
+        );
+    }
+}