/**
 * CLEO KMS Adapter — `CLEO_KMS_ADAPTER` key-backend selector.
 *
 * Exports {@link loadSigningIdentity} which returns an `AgentIdentity`
 * from `llmtxt/identity` using the backend selected by the
 * `CLEO_KMS_ADAPTER` environment variable.
 *
 * Supported backends:
 *
 * | Adapter | Env var value | Key source |
 * |---------|---------------|------------|
 * | `env`   | `"env"`       | `CLEO_SIGNING_SEED` (64-char hex) |
 * | `file`  | `"file"` (default) | `.cleo/keys/sentient.ed25519` (mode 0600) |
 * | `vault` | `"vault"`     | HashiCorp Vault `transit/` engine (stub) |
 * | `aws`   | `"aws"`       | AWS KMS Ed25519 key (stub) |
 *
 * Dev/CI: use `env` adapter. Production: use `vault` or `aws`.
 *
 * The daemon process owns the signing context. The experiment agent
 * container NEVER receives the key material directly (closes Round 2
 * attack #3 — mode-0600 keyfile is accessible to the host OS user).
 *
 * @see DESIGN.md §4.2 — KMS adapter abstraction
 * @task T1021
 */
import type { AgentIdentity } from 'llmtxt/identity';
/**
 * Supported CLEO KMS adapter backends.
 *
 * Selected by the `CLEO_KMS_ADAPTER` environment variable.
 * Defaults to `"file"` for backward compatibility with ADR-054.
 */
export type KmsAdapterKind = 'env' | 'file' | 'vault' | 'aws';
/**
 * Load a signing identity using the backend selected by `CLEO_KMS_ADAPTER`.
 *
 * The returned `AgentIdentity` from `llmtxt/identity` provides `sign()`,
 * `verify()`, and `pubkeyHex` without exposing raw private-key bytes to
 * callers. The private key is only read once per call; caching is the
 * caller's responsibility.
 *
 * @param projectRoot - Absolute path to the CLEO project root. Used by the
 *   `file` adapter to locate `.cleo/keys/sentient.ed25519`.
 * @returns An `AgentIdentity` constructed from the selected backend.
 * @throws If the selected backend cannot load key material (missing env var,
 *   wrong file permissions, network error, etc.).
 *
 * @example
 * ```ts
 * import { loadSigningIdentity } from '@cleocode/core/sentient/kms.js';
 *
 * const identity = await loadSigningIdentity(projectRoot);
 * const sig = await identity.sign(Buffer.from('hello'));
 * ```
 */
export declare function loadSigningIdentity(projectRoot: string): Promise<AgentIdentity>;
/**
 * Resolve the adapter kind from `CLEO_KMS_ADAPTER` environment variable.
 *
 * Defaults to `"file"` when the variable is absent or empty.
 *
 * @throws If the value is set but not one of the valid adapter kinds.
 */
export declare function resolveAdapterKind(): KmsAdapterKind;
/**
 * Load an `AgentIdentity` from the `CLEO_SIGNING_SEED` environment variable.
 *
 * `CLEO_SIGNING_SEED` must be a 64-character lowercase hex string encoding
 * a 32-byte Ed25519 seed. Suitable for development and CI pipelines where
 * secrets are injected as environment variables.
 *
 * @throws If `CLEO_SIGNING_SEED` is absent, malformed, or not exactly 64 hex chars.
 */
export declare function loadEnvIdentity(): Promise<AgentIdentity>;
/**
 * Load an `AgentIdentity` from a keyfile on disk.
 *
 * The keyfile must be located at `<projectRoot>/.cleo/keys/sentient.ed25519`
 * and must have UNIX permissions `0600` (owner read+write only).
 * The file must contain exactly 32 raw bytes (the Ed25519 seed).
 *
 * Refuses to load if permissions are wider than 0600 — this closes the
 * Round 2 attack surface where a prompt-injected agent running as the same
 * OS user could read the key.
 *
 * @param projectRoot - Absolute path to the CLEO project root.
 * @throws If the keyfile is missing, has wrong permissions, or wrong size.
 */
export declare function loadFileIdentity(projectRoot: string): Promise<AgentIdentity>;
/**
 * Load an `AgentIdentity` backed by HashiCorp Vault's Transit Engine.
 *
 * **STUB implementation** — this adapter is an interface-compliance skeleton.
 * Full implementation requires a Vault SDK or direct HTTP calls to the
 * Transit Engine API endpoints:
 *
 * - `POST /v1/transit/sign/<key-name>` — sign a payload
 * - `POST /v1/transit/verify/<key-name>` — verify a signature
 * - `GET /v1/transit/keys/<key-name>` — retrieve public key
 *
 * Required environment variables:
 * - `VAULT_ADDR` — Vault server address (e.g. `https://vault.example.com`)
 * - `VAULT_TOKEN` — authentication token
 * - `CLEO_KMS_VAULT_KEY` — Transit key name (default: `cleo-sentient`)
 *
 * @throws Always throws with a descriptive message indicating this is a stub.
 */
export declare function loadVaultIdentity(): Promise<AgentIdentity>;
/**
 * Load an `AgentIdentity` backed by AWS KMS.
 *
 * **STUB implementation** — this adapter is an interface-compliance skeleton.
 * Full implementation requires `@aws-sdk/client-kms` or direct calls to the
 * AWS KMS API:
 *
 * - `Sign` — sign a message digest with the KMS key
 * - `Verify` — verify a signature
 * - `GetPublicKey` — retrieve the public key bytes
 *
 * Required environment variables:
 * - `CLEO_KMS_AWS_KEY_ID` — AWS KMS Key ARN or alias
 * - Standard AWS credentials: `AWS_ACCESS_KEY_ID`, `AWS_SECRET_ACCESS_KEY`,
 *   `AWS_REGION` (or IAM role via instance metadata)
 *
 * AWS KMS Sign API (Ed25519):
 * ```
 * POST https://kms.<region>.amazonaws.com/
 *   Action: Sign
 *   KeyId: <CLEO_KMS_AWS_KEY_ID>
 *   Message: <base64-payload>
 *   MessageType: RAW
 *   SigningAlgorithm: ECDSA_SHA_256  (Ed25519 uses EdDSA; use KEY_SPEC: ECC_NIST_P256 or SM2)
 * ```
 *
 * @throws Always throws with a descriptive message indicating this is a stub.
 */
export declare function loadAwsIdentity(): Promise<AgentIdentity>;
/** Re-export AgentIdentity type for callers who import from this module. */
export type { AgentIdentity };
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