feat: redesign consumed REST client syntax and add full mapping support

Redesigns CREATE REST CLIENT to use property-based {} syntax aligned
with CREATE PUBLISHED REST SERVICE:

  CREATE REST CLIENT Module.Api (
    BaseUrl: 'https://...',
    Authentication: NONE
  )
  {
    OPERATION GetItems {
      Method: GET,
      Path: '/items/{id}',
      Parameters: ($id: String),
      Query: ($q: String),
      Headers: ('Accept' = 'application/json'),
      Response: MAPPING Module.ItemResponse {
        "Id" = "id",
      }
    }
  };

New capabilities:
- Body: TEMPLATE '...' (Rest$StringBody with value template)
- Body: MAPPING Entity { jsonField = Attr } (Rest$ImplicitMappingBody)
- Response: MAPPING Entity { Attr = jsonField } (Rest$ImplicitMappingResponseHandling)
- Nested object mappings: CREATE Assoc/Entity = jsonField { ... }
- JsonPath comments in DESCRIBE for tracing JSON flattening
- Query param types now parsed correctly (was hardcoded to String)
- DESCRIBE always double-quotes mapping identifiers for roundtrip safety
- Version feature keys and checkFeature() for published REST commands
- Documentation: quick reference, help topics, docs-site examples

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ako

cmd/mxcli/help_topics/rest.txt

@@ -15,6 +15,46 @@ DESCRIBE COMMANDS
   DESCRIBE REST CLIENT MyModule.PetStoreAPI;      -- Full MDL definition
   DESCRIBE PUBLISHED REST SERVICE MyModule.MyAPI; -- Full MDL definition
 
+CREATE REST CLIENT
+------------------
+
+  CREATE REST CLIENT Module.Api (
+    BaseUrl: 'https://api.example.com',
+    Authentication: NONE
+  )
+  {
+    OPERATION GetOrder {
+      Method: GET,
+      Path: '/orders/{id}',
+      Parameters: ($id: String),
+      Headers: ('Accept' = 'application/json'),
+      Timeout: 30,
+      Response: JSON AS $Result
+    }
+
+    OPERATION CreateOrder {
+      Method: POST,
+      Path: '/orders',
+      Headers: ('Content-Type' = 'application/json'),
+      Body: MAPPING Module.OrderRequest {
+        customerId = CustomerId,
+        amount = Amount,
+      },
+      Response: MAPPING Module.OrderResponse {
+        Id = id,
+        Status = status,
+      }
+    }
+  };
+
+  CREATE OR MODIFY REST CLIENT Module.Api ( ... ) { ... };  -- Update existing
+  DROP REST CLIENT Module.Api;
+
+  Authentication: NONE | BASIC (Username: '...', Password: '...')
+  Body: JSON FROM $var | TEMPLATE '...' | MAPPING Entity { jsonField = Attr, ... }
+  Response: JSON AS $var | STRING AS $var | FILE AS $var | STATUS AS $var | NONE
+          | MAPPING Entity { Attr = jsonField, ... }
+
 CREATE / DROP PUBLISHED REST SERVICE
 -------------------------------------
 

docs-site/src/examples/rest-integration.md

@@ -180,6 +180,67 @@ CREATE IMPORT MAPPING Integration.IMM_Order
 };
 ```
 
+## Consuming a REST API
+
+Define a reusable REST client with typed operations using `CREATE REST CLIENT`. Each operation declares its method, path, optional parameters, headers, body, and response mapping.
+
+```sql
+-- Define a client for the orders API
+CREATE REST CLIENT Integration.OrdersApi (
+  BaseUrl: 'https://api.example.com/v1',
+  Authentication: NONE
+)
+{
+  OPERATION GetOrder {
+    Method: GET,
+    Path: '/orders/{id}',
+    Parameters: ($id: String),
+    Headers: ('Accept' = 'application/json'),
+    Timeout: 30,
+    Response: JSON AS $Result
+  }
+
+  OPERATION CreateOrder {
+    Method: POST,
+    Path: '/orders',
+    Headers: ('Content-Type' = 'application/json'),
+    Body: MAPPING Integration.OrderRequest {
+      customerId = CustomerId,
+      totalAmount = TotalAmount,
+      notes = Notes,
+    },
+    Response: MAPPING Integration.OrderResponse {
+      Id = id,
+      Status = status,
+      CreatedAt = createdAt,
+    }
+  }
+};
+```
+
+Use `CREATE OR MODIFY REST CLIENT` to update an existing client without dropping it first:
+
+```sql
+CREATE OR MODIFY REST CLIENT Integration.OrdersApi (
+  BaseUrl: 'https://api.example.com/v2',
+  Authentication: BASIC (Username: 'apiuser', Password: 'secret')
+)
+{
+  OPERATION GetOrder {
+    Method: GET,
+    Path: '/orders/{id}',
+    Parameters: ($id: String),
+    Headers: ('Accept' = 'application/json'),
+    Timeout: 60,
+    Response: JSON AS $Result
+  }
+};
+```
+
+**Body types:** `JSON FROM $var`, `TEMPLATE '...'`, `MAPPING Entity { jsonField = Attr, ... }`
+**Response types:** `JSON AS $var`, `STRING AS $var`, `FILE AS $var`, `STATUS AS $var`, `NONE`, `MAPPING Entity { Attr = jsonField, ... }`
+**Authentication:** `NONE`, `BASIC (Username: '...', Password: '...')`
+
 ## Publishing a REST API
 
 Create a published REST service with CRUD operations backed by microflows.

docs/01-project/MDL_QUICK_REFERENCE.md

@@ -439,6 +439,52 @@ CREATE OR REPLACE NAVIGATION Responsive
 
 **Export levels:** `'Hidden'` (default, internal to module), `'Public'` (accessible from other modules).
 
+## Consumed REST Services
+
+| Statement | Syntax | Notes |
+|-----------|--------|-------|
+| Show clients | `SHOW REST CLIENTS [IN Module];` | List all or filter by module |
+| Describe client | `DESCRIBE REST CLIENT Module.Name;` | Re-executable CREATE |
+| Create client | See syntax below | Property-based `{}` syntax |
+| Create or modify | `CREATE OR MODIFY REST CLIENT ...` | Replaces existing |
+| Drop client | `DROP REST CLIENT Module.Name;` | |
+
+```sql
+CREATE REST CLIENT Module.Api (
+  BaseUrl: 'https://api.example.com',
+  Authentication: NONE
+)
+{
+  OPERATION GetItems {
+    Method: GET,
+    Path: '/items/{id}',
+    Parameters: ($id: String),
+    Query: ($filter: String),
+    Headers: ('Accept' = 'application/json'),
+    Timeout: 30,
+    Response: JSON AS $Result
+  }
+
+  OPERATION CreateItem {
+    Method: POST,
+    Path: '/items',
+    Headers: ('Content-Type' = 'application/json'),
+    Body: MAPPING Module.ItemRequest {
+      name = Name,
+      price = Price,
+    },
+    Response: MAPPING Module.ItemResponse {
+      Id = id,
+      Status = status,
+    }
+  }
+};
+```
+
+**Body types:** `JSON FROM $var`, `TEMPLATE '...'`, `MAPPING Entity { jsonField = Attr, ... }`
+**Response types:** `JSON AS $var`, `STRING AS $var`, `FILE AS $var`, `STATUS AS $var`, `NONE`, `MAPPING Entity { Attr = jsonField, ... }`
+**Authentication:** `NONE`, `BASIC (Username: '...', Password: '...')`
+
 ## Published REST Services
 
 | Statement | Syntax | Notes |