ARC56: Extended App Description

ARCs/arc-0056.md

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+---
+arc: 56
+title: Extended App Description
+description: Adds information to the ABI JSON description
+author: Joe Polny (@joe-p)
+discussions-to: https://github.com/algorandfoundation/ARCs/issues/258
+status: Draft
+type: Standards Track
+category: ARC
+created: 2023-11-14
+requires: 4, 22, 28
+---
+
+
+## Abstract
+This ARC takes the existing JSON description of a contract as described in [ARC-4](./arc-0004.md) and adds more fields for the purpose of client interaction
+
+## Motivation
+The data provided by ARC-4 is missing a lot of critical information that clients should know when interacting with an app. This means ARC-4 is insufficient to generate type-safe clients that provide a superior developer experience.
+
+On the other hand, [ARC-32](./arc-0032.md) provides the vast majority of useful information that can be used to <a href="https://github.com/algorandfoundation/algokit-cli/blob/main/docs/features/generate.md#1-typed-clients">generate typed clients</a>, but requires a separate JSON file on top of the ARC-4 json file, which adds extra complexity and cognitive overhead.
+
+## Specification
+
+### Contract Interface
+Every application is described via the following interface which is an extension of the `Contract` interface described in [ARC-4](./arc-0004.md).
+
+```ts
+/** Describes the entire contract. This interface is an extension of the interface described in ARC-4 */
+interface Contract {
+  /** The ARCs used and/or supported by this contract */
+  arcs: number[],
+  /** A user-friendly name for the contract */
+  name: string;
+  /** Optional, user-friendly description for the interface */
+  desc?: string;
+  /**
+   * Optional object listing the contract instances across different networks
+   */
+  networks?: {
+    /**
+     * The key is the base64 genesis hash of the network, and the value contains
+     * information about the deployed contract in the network indicated by the
+     * key. A key containing the human-readable name of the network MAY be 
+     * included, but the corresponding genesis hash key MUST also be defined
+     */
+    [network: string]: {
+      /** The app ID of the deployed contract in this network */
+      appID: number;
+    };
+  };
+  /** Named structs use by the application */
+  structs: { [structName: StructName]: StructFields };
+  /** All of the methods that the contract implements */
+  methods: Method[];
+  state: {
+    /** Defines the values that should be used for GlobalNumUint, GlobalNumByteSlice, LocalNumUint, and LocalNumByteSlice when creating the application  */
+    schema: {
+      global: {
+        ints: number;
+        bytes: number;
+      };
+      local: {
+        ints: number;
+        bytes: number;
+      };
+    };
+    /** Describes single key-value pairs in the application's state */
+    keys: {
+      global: StorageKey[];
+      local: StorageKey[];
+      box: StorageKey[];
+    };
+    /** Describes key-value maps in the application's state */
+    maps: {
+      global: StorageMap[];
+      local: StorageMap[];
+      box: StorageMap[];
+    };
+  };
+  /** Supported bare actions for the contract. An action is a combination of call/create and an OnComplete */
+  bareActions: {
+    /** OnCompletes this method allows when appID === 0 */
+    create: ('NoOp' | 'OptIn' | 'DeleteApplication')[];
+    /** OnCompletes this method allows when appID !== 0 */
+    call: ('NoOp' | 'OptIn' | 'CloseOut' | 'ClearState' | 'UpdateApplication' | 'DeleteApplication')[];
+  };
+  /** Information about the TEAL */
+  sourceInfo: SourceInfo;
+  /** The pre-compiled TEAL that may contain template variables. MUST be omitted if included as part of ARC23, but otherwise MUST be defined. */
+  source?: {
+    /** The approval program */
+    approval: string;
+    /** The clear program */
+    clear: string;
+  };
+  /** ARC-28 events that MAY be emitted by this contract */
+  events?: Array<Event>;
+  /** Template Variables */
+  templateVariables?: {
+    /** The name of the template variable as it appears in the TEAL */
+    name: string;
+    /** The type of the value expected in the template variable */
+    type: ABIType | AVMBytes | StructName;
+  }[];
+}
+```
+
+### Method Interface
+
+Every method in the contract is described via a `Method` interface. This interface is an extension of the one defined in [ARC-4](./arc-0004.md).
+
+```ts
+/** Describes a method in the contract. This interface is an extension of the interface described in ARC-4 */
+interface Method {
+  /** The name of the method */
+  name: string;
+  /** Optional, user-friendly description for the method */
+  desc?: string;
+  /** The arguments of the method, in order */
+  args: Array<{
+    /** The type of the argument */
+    type: ABIType;
+    /** If the type is a struct, the name of the struct */
+    struct?: StructName;
+    /** Optional, user-friendly name for the argument */
+    name?: string;
+    /** Optional, user-friendly description for the argument */
+    desc?: string;
+    /** The default value that clients should use. MUST be base64 encoded bytes */
+    defaultValue?: string;
+  }>;
+  /** Information about the method's return value */
+  returns: {
+    /** The type of the return value, or "void" to indicate no return value. */
+    type: ABIType;
+    /** If the type is a struct, the name of the struct */
+    struct?: StructName;
+    /** Optional, user-friendly description for the return value */
+    desc?: string;
+  };
+  /** an action is a combination of call/create and an OnComplete */
+  actions: {
+    /** OnCompletes this method allows when appID === 0 */
+    create: ('NoOp' | 'OptIn' | 'DeleteApplication')[];
+    /** OnCompletes this method allows when appID !== 0 */
+    call: ('NoOp' | 'OptIn' | 'CloseOut' | 'ClearState' | 'UpdateApplication' | 'DeleteApplication')[];
+  };
+  /** If this method does not write anything to the ledger (ARC-22) */
+  readonly: boolean;
+  /** ARC-28 events that MAY be emitted by this method */
+  events?: Array<Event>;
+  /** Information that clients can use when calling the method */
+  recommendations?: {
+    /** The number of inner transactions the caller should cover the fees for */
+    innerTransactionCount?: number;
+    /** Recommended box references to include */
+    boxes?: {
+      /** The app ID for the box */
+      app: number;
+      /** The base64 encoded box key */
+      key: string;
+      /** The number of bytes being read from the box */
+      readBytes: number;
+      /** The number of bytes being written to the box */
+      writeBytes: number;
+    };
+    /** Recommended foreign accounts */
+    accounts?: string[];
+    /** Recommended foreign apps */
+    apps?: number[];
+    /** Recommended foreign assets */
+    assets?: number[];
+  };
+}
+```
+
+### Event Interface
+
+[ARC-28](./arc-0028.md) events are described using an extension of the original interface described in the ARC, with the addition of an optional struct field for arguments
+
+```ts
+interface Event {
+  /** The name of the event */
+  name: string;
+  /** Optional, user-friendly description for the event */
+  desc?: string;
+  /** The arguments of the event, in order */
+  args: Array<{
+    /** The type of the argument */
+    type: ABIType;
+    /** Optional, user-friendly name for the argument */
+    name?: string;
+    /** Optional, user-friendly description for the argument */
+    desc?: string;
+    /** If the type is a struct, the name of the struct */
+    struct?: StructName;
+  }>;
+}
+```
+
+
+### Type Interfaces
+
+The types defined in [ARC-4](./arc-0004.md) may not fully described the best way to use the ABI values as intended by the contract developers. These type interfaces are intended to supplement ABI types so clients can interact with the contract as intended.
+
+```ts
+/** An ABI-encoded type */
+type ABIType = string;
+
+/** The name of a defined struct */
+type StructName = string;
+
+/** Raw byteslice without the length prefixed that is specified in ARC-4 */
+type AVMBytes = 'bytes';
+
+/** Mapping of named structs to the ABI type of their fields */
+interface StructFields {
+  [fieldName: string]: ABIType | StructFields;
+}
+```
+
+### Storage Interfaces
+
+These interfaces properly describe how app storage is access within the contract
+
+```ts
+/** Describes a single key in app storage */
+interface StorageKey {
+  /** Description of what this storage key holds */
+  desc?: string;
+  /** The type of the key */
+  keyType: ABIType | AVMBytes | StructName;
+  /** The type of the value */
+  valueType: ABIType | AVMBytes | StructName;
+  /** The bytes of the key encoded as base64 */
+  key: string;
+}
+
+interface StorageMap {
+  /** Description of what the key-value pairs in this mapping hold */
+  desc?: string;
+  /** The type of the keys in the map */
+  keyType: ABIType | AVMBytes | StructName;
+  /** The type of the values in the map */
+  valueType: ABIType | AVMBytes | StructName;
+  /** The prefix of the map, encoded as a utf-8 string */
+  prefix: string;
+}
+```
+
+### SourceInfo Interface
+
+This interface gives clients more information about the contract's source code.
+
+```ts
+interface SourceInfo {
+  /** The line of pre-compiled TEAL */
+  teal: number;
+  /** The program counter offset(s) that correspond to this line of TEAL */
+  pc?: Array<number>;
+  /** A human-readable string that describes the error when the program fails at this given line of TEAL */
+  error?: string;
+}
+```
+
+### Template Variables
+
+Template variables are variables in the TEAL that should be substitued prior to compilation. Template variables **MUST** be an argument to either `pushints` or `pusbytes`. Using these opcodes is important to ensure that the program does not add them to the constant blocks. 
+
+#### Examples
+##### Valid
+```
+pushints TMPL_FOO
+pushbytes TMPL_BAR
+```
+
+#### Invalid
+
+Template variables MUST use pushints or pushbytes
+
+```
+int TMPL_FOO
+byte TMPL_BYTE
+```
+
+Template variables MUST be the entire argument
+
+```
+pushints 123TMPL_FOO
+pusbytes 0xdeadTMPL_BAR
+```
+
+## Rationale
+ARC-32 essentially addresses the same problem, but it requires the generation of two separate JSON files and the ARC-32 JSON file contains the ARC-4 JSON file within it (redundant information). The goal of this ARC is to create one JSON schema that is backwards compatible with ARC-4 clients, but contains the relevant information needed to automatically generate comprehensive client experiences.
+
+### State
+
+Describes all of the state that MAY exist in the app and how one should decode values. The schema provides the required schema when creating the app. 
+
+### Named Structs
+
+It is common for high-level languages to support named structs, which gives names to the indexes of elements in an ABI tuple. The same structs should be useable on the client-side just as they are used in the contract.
+
+### Action
+
+This is one of the biggest deviation from ARC-32, but provides a much simpler interface to describe and understand what any given method can do. 
+
+## Backwards Compatibility
+The JSON schema defined in this ARC should be compatible with all ARC-4 clients, provided they don't do any strict schema checking for extraneous fields.
+
+## Test Cases
+NA
+
+## Reference Implementation
+TODO
+
+## Security Considerations
+The type values used in methods **MUST** be correct, because if they were not then the method would not be callable. For state, however, it is possible to have an incorrect type encoding defined. Any significant security concern from this possibility is not immediately evident, but it is worth considering.  
+
+## Copyright
+Copyright and related rights waived via <a href="https://creativecommons.org/publicdomain/zero/1.0/">CCO</a>.