diff --git a/src/asherah.d.ts b/src/asherah.d.ts
index b7892e6..3ba4454 100644
--- a/src/asherah.d.ts
+++ b/src/asherah.d.ts
@@ -3,50 +3,51 @@
 /// <reference types="node" />
 export type AsherahConfig = {
     /** The name of this service (Required) */
-    ServiceName: string;
+    readonly ServiceName: string;
     /** The name of the product that owns this service (Required) */
-    ProductID: string;
+    readonly ProductID: string;
     /** The amount of time a key is considered valid */
-    ExpireAfter: number | null;
+    readonly ExpireAfter: number | null;
     /** The amount of time before cached keys are considered stale */
-    CheckInterval: number | null;
-    /** Determines the type of metastore to use for persisting keys (Required) { "rdbms", "dynamodb", "memory" } */
-    Metastore: string;
+    readonly CheckInterval: number | null;
+    /** Determines the type of metastore to use for persisting keys (Required) */
+    readonly Metastore: "rdbms" | "dynamodb" | "test-debug-memory" | string;
     /** The database connection string (Required if metastore=rdbms) */
-    ConnectionString: string | null;
-    /** Required for Aurora sessions using write forwarding { "eventual", "global", "session" } */
-    ReplicaReadConsistency: string | null;
+    readonly ConnectionString: string | null;
+    /** Required for Aurora sessions using write forwarding */
+    readonly ReplicaReadConsistency: "eventual" | "global" | "session" | string | null;
     /** An optional endpoint URL (hostname only or fully qualified URI) (only supported by metastore=dynamodb) */
-    DynamoDBEndpoint: string | null;
+    readonly DynamoDBEndpoint: string | null;
     /** The AWS region for DynamoDB requests (defaults to globally configured region) (only supported by metastore=dynamodb) */
-    DynamoDBRegion: string | null;
+    readonly DynamoDBRegion: string | null;
     /** The table name for DynamoDB (only supported by metastore=dynamodb) */
-    DynamoDBTableName: string | null;
+    readonly DynamoDBTableName: string | null;
     /** Define the maximum number of sessions to cache (Default 1000) */
-    SessionCacheMaxSize: number | null;
+    readonly SessionCacheMaxSize: number | null;
     /** The amount of time a session will remain cached (Default 2h) */
-    SessionCacheDuration: number | null;
-    /** Configures the master key management service (Default kms) { "aws", "static" } */
-    KMS: string | null;
+    readonly SessionCacheDuration: number | null;
+    /** Configures the master key management service (Default kms) */
+    readonly KMS: "aws" | "test-debug-static" | string | null;
     /** Dictionary of REGION: ARN (required if kms=aws) */
-    RegionMap: {
-        [name: string]: string;
+    readonly RegionMap: {
+        readonly [name: string]: string;
     } | null;
     /** The preferred AWS region (required if kms=aws) */
-    PreferredRegion: string | null;
+    readonly PreferredRegion: string | null;
     /** Configure the metastore to use regional suffixes (only supported by metastore=dynamodb) */
-    EnableRegionSuffix: boolean | null;
+    readonly EnableRegionSuffix: boolean | null;
     /** Enable shared session caching */
-    EnableSessionCaching: boolean | null;
+    readonly EnableSessionCaching: boolean | null;
     /** Enable verbose logging output */
-    Verbose: boolean | null;
+    readonly Verbose: boolean | null;
     /** Disable the zero-copy optimization for the cobhan buffer protocol */
-    DisableZeroCopy: boolean | null;
+    readonly DisableZeroCopy: boolean | null;
     /** Enable canary buffer corruption checks (default: false) */
-    EnableCanaries: boolean | null;
+    readonly EnableCanaries: boolean | null;
 };
 
-type LogHookCallback = (level: number, message: string) => void;
+/** Callback function type for log hook */
+export type LogHookCallback = (level: number, message: string) => void;
 
 export declare function setup(config: AsherahConfig): void;
 export declare function setup_async(config: AsherahConfig): Promise<void>;