fix: support multiple XPath predicates [cond1][cond2] in WHERE clauses

Consecutive bracket predicates without explicit AND/OR are now parsed
as implicit AND, matching standard Mendix XPath syntax. Fixes #144.

Also adds `mxcli syntax xpath` help topic and updates the xpath skill.

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

Author: ako

.claude/skills/mendix/xpath-constraints.md

@@ -167,10 +167,13 @@ DATAGRID dg (
 }
 ```
 
-Multiple bracket constraints can be chained:
+Multiple bracket constraints can be chained. Consecutive brackets without an operator are treated as AND (standard Mendix XPath):
 
 ```mdl
--- All AND: separate brackets
+-- Consecutive brackets (implicit AND) — standard Mendix XPath syntax
+DataSource: DATABASE FROM Module.Entity WHERE [IsActive = true][Stock > 0]
+
+-- Explicit AND: same result
 DataSource: DATABASE FROM Module.Entity WHERE [IsActive = true] AND [Stock > 0]
 
 -- Mix with OR: combines into single bracket

cmd/mxcli/help.go

@@ -176,6 +176,7 @@ Available topics:
   fragment    - Show fragment (reusable widget group) syntax
   java-action - Show Java action syntax (CREATE/DESCRIBE/CALL, type params, EXPOSED AS)
   business-events - Show business event service syntax
+  xpath       - Show XPath constraint syntax for WHERE clauses
   oql         - Show OQL query execution syntax (mxcli oql)
   sql         - Show external SQL query execution syntax (mxcli sql)
   errors      - List validation errors and how to fix them
@@ -240,6 +241,8 @@ Example:
 			showTopicHelp("java-action")
 		case "business-events", "businessevents", "business_events", "be":
 			showTopicHelp("business-events")
+		case "xpath", "xpath-constraints":
+			showTopicHelp("xpath")
 		case "oql":
 			showTopicHelp("oql")
 		case "sql", "external-sql":

cmd/mxcli/help_topics/xpath.txt

@@ -0,0 +1,86 @@
+XPath Constraints in MDL
+========================
+
+XPath expressions filter data in RETRIEVE statements, page data sources,
+conditional visibility/editability, and security rules.
+
+SYNTAX
+------
+
+  Single predicate:    WHERE [condition]
+  Multiple predicates: WHERE [cond1][cond2]        -- implicit AND
+  Explicit operators:  WHERE [cond1] AND [cond2]
+                       WHERE [cond1] OR [cond2]
+
+OPERATORS
+---------
+
+  =, !=, <, >, <=, >=       Comparison
+  and, or                    Boolean (lowercase in XPath)
+  not(expr)                  Negation function
+  contains(attr, 'text')     String contains
+  starts-with(attr, 'text')  String starts-with
+  true(), false()            Boolean literals
+
+EXAMPLES
+--------
+
+  -- Simple comparison
+  WHERE [Status = 'Active']
+  WHERE [Amount >= 100]
+
+  -- Multiple predicates (implicit AND)
+  WHERE [IsActive = true][Stock > 0]
+
+  -- Boolean logic
+  WHERE [State = 'Ready' and Priority > 5]
+  WHERE [State = 'Pending' or State = 'Processing']
+  WHERE [not(IsArchived)]
+
+  -- Association path traversal
+  WHERE [Module.Order_Customer/Module.Customer/Name = $Name]
+
+  -- Nested predicates on path steps
+  WHERE [Module.Line_Order/Module.Order[State = 'Active']/Total > 100]
+
+  -- Mendix tokens (runtime values)
+  WHERE [System.owner = '[%CurrentUser%]']
+  WHERE [CreatedDate > [%CurrentDateTime%]]
+
+  -- ID pseudo-attribute
+  WHERE [id = $currentObject]
+
+USAGE CONTEXTS
+--------------
+
+  Microflow RETRIEVE:
+    RETRIEVE $Orders FROM Module.Order
+      WHERE [State = 'Completed'][IsPaid = true]
+      SORT BY OrderDate DESC;
+
+  Page data source:
+    DATAGRID dg (
+      DataSource: DATABASE FROM Module.Order
+        WHERE [State != 'Cancelled'][Amount > 0]
+        SORT BY OrderDate DESC
+    )
+
+  Conditional visibility:
+    CONTAINER c (Visible: [IsActive = true])
+
+  Conditional editability:
+    TEXTBOX txt (Editable: [Status != 'Closed'])
+
+  Security (string literal):
+    GRANT Module.Role ON Module.Entity (READ *)
+      WHERE '[System.owner = ''[%CurrentUser%]'']';
+
+DIFFERENCES FROM MENDIX EXPRESSIONS
+------------------------------------
+
+  XPath [...]                    Mendix expression
+  ─────────────                  ──────────────────
+  / is path traversal            / is also division
+  and, or (lowercase)            AND, OR (uppercase)
+  not(expr) function             NOT expr keyword
+  '[%CurrentUser%]' (quoted)     [%CurrentUser%] (unquoted)

mdl/grammar/MDLParser.g4

@@ -1192,7 +1192,7 @@ rollbackStatement
 // RETRIEVE $ProductList FROM MfTest.Product WHERE Code = $SearchCode SORT BY Name ASC LIMIT 1;
 retrieveStatement
     : RETRIEVE VARIABLE FROM retrieveSource
-      (WHERE (xpathConstraint | expression))?
+      (WHERE (xpathConstraint (andOrXpath? xpathConstraint)* | expression))?
       (SORT_BY sortColumn (COMMA sortColumn)*)?
       (LIMIT limitExpr=expression)?
       (OFFSET offsetExpr=expression)?
@@ -2027,7 +2027,7 @@ attributeListV3
 dataSourceExprV3
     : VARIABLE                                        // $ParamName
     | DATABASE FROM? qualifiedName                    // DATABASE [FROM] Entity [WHERE ...] [SORT BY ...]
-      (WHERE (xpathConstraint (andOrXpath xpathConstraint)* | expression))?
+      (WHERE (xpathConstraint (andOrXpath? xpathConstraint)* | expression))?
       (SORT_BY sortColumn (COMMA sortColumn)*)?
     | MICROFLOW qualifiedName microflowArgsV3?        // MICROFLOW Module.Flow
     | NANOFLOW qualifiedName microflowArgsV3?         // NANOFLOW Module.Flow