Auto doc...

README.md

@@ -5,7 +5,7 @@
 ## Features
 
 - **Portability**: A single statically compiled executable compatible with any Linux 3.2+ machine (as well as possible to compile and run on Windows and Mac OS X)
-- **LSP Server**: Real-time syntax checking, validation, autocomplete, hover documentation, and navigation (Go to Definition/References).
+- **LSP Server**: Real-time syntax checking, validation, autocomplete, hover documentation, navigation (Go to Definition/References), and Inlay Hints (inline types and evaluation).
 - **Builder**: Merges multiple configuration files into a single, ordered output file.
 - **Formatter**: Standardizes configuration file formatting.
 - **Validator**: Advanced semantic validation using [CUE](https://cuelang.org/) schemas, ensuring type safety and structural correctness.
@@ -16,9 +16,13 @@ Few additional features have been added to the standard MARTe configuration lang
 
 - Multi file configuration support
   - Multi file definition merging
-  - File level namespace / node
-- Doc-strings support
-- Pragmas for warning suppression / documentation
+  - File level namespace / node (`#package`)
+- Variables and Constants
+  - Overrideable variables (`#var`)
+  - Fixed constants (`#let`)
+  - Powerful expressions (arithmetic, bitwise, string concatenation)
+- Doc-strings support (`//#`) for objects, fields, and variables
+- Pragmas (`//!`) for warning suppression / documentation
 
 ## Documentation
 

docs/CODE_DOCUMENTATION.md

@@ -32,16 +32,17 @@ internal/
 
 Responsible for converting MARTe configuration text into structured data.
 
-*   **Lexer (`lexer.go`)**: Tokenizes the input stream. Handles MARTe specific syntax like `#package`, `//!` pragmas, and `//#` docstrings. Supports standard identifiers and `#`-prefixed identifiers.
-*   **Parser (`parser.go`)**: Recursive descent parser. Converts tokens into a `Configuration` object containing definitions, comments, and pragmas.
-*   **AST (`ast.go`)**: Defines the node types (`ObjectNode`, `Field`, `Value`, `VariableDefinition`, etc.). All nodes implement the `Node` interface providing position information.
+*   **Lexer (`lexer.go`)**: Tokenizes the input stream. Handles MARTe specific syntax like `#package`, `#let`, `//!` pragmas, and `//#` docstrings. Supports standard identifiers and `#`-prefixed identifiers. Recognizes advanced number formats (hex `0x`, binary `0b`).
+*   **Parser (`parser.go`)**: Recursive descent parser. Converts tokens into a `Configuration` object containing definitions, comments, and pragmas. Implements expression parsing with precedence.
+*   **AST (`ast.go`)**: Defines the node types (`ObjectNode`, `Field`, `Value`, `VariableDefinition`, `BinaryExpression`, etc.). All nodes implement the `Node` interface providing position information.
 
 ### 2. `internal/index`
 
 The brain of the system. It maintains a holistic view of the project.
 
 *   **ProjectTree**: The central data structure. It holds the root of the configuration hierarchy (`Root`), references, and isolated files.
-*   **ProjectNode**: Represents a logical node in the configuration. Since a node can be defined across multiple files (fragments), `ProjectNode` aggregates these fragments. It also stores locally defined variables in its `Variables` map.
+*   **ScanDirectory**: Recursively walks the project directory to find all `.marte` files, adding them to the tree even if they contain partial syntax errors.
+*   **ProjectNode**: Represents a logical node in the configuration. Since a node can be defined across multiple files (fragments), `ProjectNode` aggregates these fragments. It also stores locally defined variables and constants in its `Variables` map.
 *   **NodeMap**: A hash map index (`map[string][]*ProjectNode`) for $O(1)$ symbol lookups, optimizing `FindNode` operations.
 *   **Reference Resolution**: The `ResolveReferences` method links `Reference` objects to their target `ProjectNode` or `VariableDefinition`. It uses `ResolveName` (exported) which respects lexical scoping rules by searching the hierarchy upwards from the reference's container, using `FindNode` for deep searches within each scope.
 
@@ -53,10 +54,10 @@ Ensures configuration correctness.
 *   **Checks**:
     *   **Structure**: Duplicate fields, invalid content.
     *   **Schema**: Unifies nodes with CUE schemas (loaded via `internal/schema`) to validate types and mandatory fields.
-    *   **Signals**: Verifies that signals referenced in GAMs exist in DataSources and match types.
+    *   **Signals**: Verifies that signals referenced in GAMs exist in DataSources and match types. Performs project-wide consistency checks for implicit signals.
     *   **Threading**: Checks `CheckDataSourceThreading` to ensure non-multithreaded DataSources are not shared across threads in the same state.
     *   **Ordering**: `CheckINOUTOrdering` verifies that for `INOUT` signals, the producing GAM appears before the consuming GAM in the thread's execution list.
-    *   **Variables**: `CheckVariables` validates variable values against their defined CUE types (e.g. `uint`, regex). `CheckUnresolvedVariables` ensures all used variables are defined.
+    *   **Variables**: `CheckVariables` validates variable values against their defined CUE types. Prevents external overrides of `#let` constants. `CheckUnresolvedVariables` ensures all used variables are defined.
     *   **Unused**: Detects unused GAMs and Signals (suppressible via pragmas).
 
 ### 4. `internal/lsp`
@@ -64,11 +65,13 @@ Ensures configuration correctness.
 Implements the Language Server Protocol.
 
 *   **Server (`server.go`)**: Handles JSON-RPC messages over stdio.
+*   **Evaluation**: Implements a lightweight expression evaluator to show evaluated values in Hover and completion snippets.
 *   **Incremental Sync**: Supports `textDocumentSync: 2`. `HandleDidChange` applies patches to the in-memory document buffers using `offsetAt` logic.
 *   **Features**:
-    *   `HandleCompletion`: Context-aware suggestions (Schema fields, Signal references, Class names).
-    *   `HandleHover`: Shows documentation, signal types, and usage analysis (e.g., "Used in GAMs: Controller (Input)").
+    *   `HandleCompletion`: Context-aware suggestions (Macros, Schema fields, Signal references, Class names).
+    *   `HandleHover`: Shows documentation (including docstrings for variables), evaluated signal types/dimensions, and usage analysis.
     *   `HandleDefinition` / `HandleReferences`: specific lookup using the `index`.
+    *   `HandleRename`: Project-wide renaming supporting objects, fields, and signals (including implicit ones).
 
 ### 5. `internal/builder`
 
@@ -76,6 +79,7 @@ Merges multiple MARTe files into a single output.
 
 *   **Logic**: It parses all input files, builds a temporary `ProjectTree`, and then reconstructs the source code.
 *   **Merging**: It interleaves fields and subnodes from different file fragments to produce a coherent single-file configuration, respecting the `#package` hierarchy.
+*   **Evaluation**: Evaluates all expressions and variable references into concrete MARTe values in the final output. Prevents overrides of `#let` constants.
 
 ### 6. `internal/schema`
 

docs/CONFIGURATION_GUIDE.md

@@ -20,22 +20,13 @@ Objects are defined using `+` (public/instantiated) or `$` (template/class-like)
 ### Fields and Values
 - **Fields**: Alphanumeric identifiers (e.g., `Timeout`, `CycleTime`).
 - **Values**:
-  - Integers: `10`, `-5`, `0xFA`
+  - Integers: `10`, `-5`, `0xFA`, `0b1011`
   - Floats: `3.14`, `1e-3`
   - Strings: `"Text"`
   - Booleans: `true`, `false`
   - References: `MyObject`, `MyObject.SubNode`
   - Arrays: `{ 1 2 3 }` or `{ "A" "B" }`
 
-### Comments and Documentation
-- Line comments: `// This is a comment`
-- Docstrings: `//# This documents the following node`. These appear in hover tooltips.
-
-```marte
-//# This is the main application
-+App = { ... }
-```
-
 ## 2. Signals and Data Flow
 
 Signals define how data moves between DataSources (drivers) and GAMs (algorithms).
@@ -73,14 +64,99 @@ GAMs declare inputs and outputs. You can refer to signals directly or alias them
 }
 ```
 
-### Threading Rules
-**Validation Rule**: A DataSource that is **not** marked as multithreaded (default) cannot be used by GAMs running in different threads within the same State.
+## 3. Multi-file Projects
 
-**Ordering Rule**: For `INOUT` signals (data dependency within a thread), the Producer GAM must appear **before** the Consumer GAM in the thread's `Functions` list. This ensures correct data flow within the cycle. This rule is skipped if the DataSource is marked as `multithreaded: true`.
+You can split your configuration into multiple files.
 
-To allow sharing, the DataSource class in the schema must have `#meta: multithreaded: true`.
+### Namespaces
+Use `#package` to define where the file's content fits in the hierarchy.
 
-## 3. Schemas and Validation
+**file1.marte**
+```marte
+#package MyApp.Controller
++MyController = { ... }
+```
+
+This places `MyController` under `MyApp.Controller`.
+
+### Building
+The `build` command merges all files.
+
+```bash
+mdt build -o final.marte src/*.marte
+```
+
+## 4. Variables and Constants
+
+You can define variables to parameterize your configuration.
+
+### Variables (`#var`)
+Variables can be defined at any level and can be overridden externally (e.g., via CLI).
+
+```marte
+//# Default timeout
+#var Timeout: uint32 = 100
+
++MyObject = {
+    Class = Timer
+    Timeout = $Timeout
+}
+```
+
+### Constants (`#let`)
+Constants are like variables but **cannot** be overridden externally. They are ideal for internal calculations or fixed parameters.
+
+```marte
+//# Sampling period
+#let Ts: float64 = 0.001
+
++Clock = {
+    Class = HighResClock
+    Period = @Ts
+}
+```
+
+### Reference Syntax
+Reference a variable or constant using `$` or `@`:
+
+```marte
+Field = $MyVar
+// or
+Field = @MyVar
+```
+
+### Expressions
+You can use operators in field values. Supported operators:
+- **Math**: `+`, `-`, `*`, `/`, `%`, `^` (XOR), `&`, `|` (Bitwise)
+- **String Concatenation**: `..`
+- **Parentheses**: `(...)` for grouping
+
+```marte
+Field1 = 10 + 20 * 2  // 50
+Field2 = "Hello " .. "World"
+Field3 = ($MyVar + 5) * 2
+```
+
+### Build Override
+You can override variable values during build (only for `#var`):
+
+```bash
+mdt build -vMyVar=200 src/*.marte
+```
+
+## 5. Comments and Documentation
+
+- Line comments: `// This is a comment`
+- Docstrings: `//# This documents the following node`. These appear in hover tooltips.
+
+```marte
+//# This is the main application
++App = { ... }
+```
+
+Docstrings work for objects, fields, variables, and constants.
+
+## 6. Schemas and Validation
 
 `mdt` validates your configuration against CUE schemas.
 
@@ -112,29 +188,7 @@ package schema
 }
 ```
 
-## 4. Multi-file Projects
-
-You can split your configuration into multiple files.
-
-### Namespaces
-Use `#package` to define where the file's content fits in the hierarchy.
-
-**file1.marte**
-```marte
-#package MyApp.Controller
-+MyController = { ... }
-```
-
-This places `MyController` under `MyApp.Controller`.
-
-### Building
-The `build` command merges all files.
-
-```bash
-mdt build -o final.marte src/*.marte
-```
-
-## 5. Pragmas (Suppressing Warnings)
+## 7. Pragmas (Suppressing Warnings)
 
 If validation is too strict, you can suppress warnings using pragmas (`//!`).
 
@@ -163,43 +217,13 @@ If validation is too strict, you can suppress warnings using pragmas (`//!`).
   }
   ```
 
-## 6. Variables
+- **Global Suppression**:
+  ```marte
+  //! allow(unused)
+  //! allow(implicit)
+  ```
 
-You can define variables using `#var`. The type expression supports CUE syntax.
-
-```marte
-#var MyVar: uint32 = 100
-#var Env: "PROD" | "DEV" = "DEV"
-```
-
-### Usage
-Reference a variable using `$` (preferred) or `@`:
-
-```marte
-Field = $MyVar
-// or
-Field = @MyVar
-```
-
-### Expressions
-You can use operators in field values. Supported operators:
-- **Math**: `+`, `-`, `*`, `/`, `%`, `^` (XOR), `&`, `|` (Bitwise)
-- **String Concatenation**: `..`
-
-```marte
-Field1 = 10 + 20 * 2  // 50
-Field2 = "Hello " .. "World"
-Field3 = $MyVar + 5
-```
-
-### Build Override
-You can override variable values during build:
-
-```bash
-mdt build -vMyVar=200 -vEnv="PROD" src/*.marte
-```
-
-## 7. Validation Rules (Detail)
+## 8. Validation Rules (Detail)
 
 ### Data Flow Validation
 `mdt` checks for logical data flow errors:
@@ -215,5 +239,17 @@ To allow sharing, the DataSource class in the schema must have `#meta: multithre
 ### Implicit vs Explicit Signals
 - **Explicit**: Signal defined in `DataSource.Signals`.
 - **Implicit**: Signal used in GAM but not defined in DataSource. `mdt` reports a warning unless suppressed.
+- **Consistency**: All references to the same logical signal (same name in same DataSource) must share the same `Type` and size properties.
 
+## 9. Editor Features (LSP)
 
+The `mdt` LSP server provides several features to improve productivity.
+
+### Inlay Hints
+Inlay hints provide real-time contextual information directly in the editor:
+
+- **Signal Metadata**: Signal usages in GAMs display their evaluated type and size, e.g., `Sig1` **`::uint32[10x1]`**.
+- **Object Class**: References to objects show the object's class, e.g., `DataSource = ` **`FileReader::`** `DS`.
+- **Expression Evaluation**:
+  - Complex expressions show their result at the end of the line, e.g., `Expr = 10 + 20` **` => 30`**.
+  - Variable references show their current value inline, e.g., `@MyVar` **`(=> 10)`**.

docs/TUTORIAL.md

@@ -148,7 +148,46 @@ make build
 
 This produces `app.marte` (or `final_app.marte`), which contains the flattened, merged configuration ready for the MARTe framework.
 
-## Step 6: Advanced - Custom Schema
+## Step 6: Using Variables and Expressions
+
+You can parameterize your application using variables. Let's define a constant for the sampling frequency.
+
+Modify `src/app.marte`:
+
+```marte
+#package MyContollApp
+
+//# Sampling frequency in Hz
+#let SamplingFreq: uint32 = 100
+
++App = {
+    // ...
+    +Functions = {
+        +Converter = {
+            Class = IOGAM
+            InputSignals = {
+                TimeIn = {
+                    DataSource = Timer
+                    Type = uint32
+                    Frequency = $SamplingFreq
+                    Alias = Time
+                }
+            }
+            // ...
+        }
+    }
+}
+```
+
+You can also use expressions for calculations:
+
+```marte
+#let CycleTime: float64 = 1.0 / $SamplingFreq
+```
+
+LSP will show you the evaluated values directly in the code via **Inlay Hints** (e.g., `CycleTime: 0.01`) and in the hover documentation.
+
+## Step 7: Advanced - Custom Schema
 
 Suppose you want to enforce that your DataSources support multithreading. You can modify `.marte_schema.cue`.
 

internal/builder/builder.go

@@ -213,17 +213,21 @@ func (b *Builder) collectVariables(tree *index.ProjectTree) {
 			for _, def := range frag.Definitions {
 				if vdef, ok := def.(*parser.VariableDefinition); ok {
 					if valStr, ok := b.Overrides[vdef.Name]; ok {
-						p := parser.NewParser("Temp = " + valStr)
-						cfg, _ := p.Parse()
-						if len(cfg.Definitions) > 0 {
-							if f, ok := cfg.Definitions[0].(*parser.Field); ok {
-								b.variables[vdef.Name] = f.Value
-								continue
+						if !vdef.IsConst {
+							p := parser.NewParser("Temp = " + valStr)
+							cfg, _ := p.Parse()
+							if len(cfg.Definitions) > 0 {
+								if f, ok := cfg.Definitions[0].(*parser.Field); ok {
+									b.variables[vdef.Name] = f.Value
+									continue
+								}
 							}
 						}
 					}
 					if vdef.DefaultValue != nil {
-						b.variables[vdef.Name] = vdef.DefaultValue
+						if _, ok := b.variables[vdef.Name]; !ok || vdef.IsConst {
+							b.variables[vdef.Name] = vdef.DefaultValue
+						}
 					}
 				}
 			}

internal/formatter/formatter.go

@@ -103,7 +103,11 @@ func (f *Formatter) formatDefinition(def parser.Definition, indent int) int {
 		fmt.Fprintf(f.writer, "%s}", indentStr)
 		return d.Subnode.EndPosition.Line
 	case *parser.VariableDefinition:
-		fmt.Fprintf(f.writer, "%s#var %s: %s", indentStr, d.Name, d.TypeExpr)
+		macro := "#var"
+		if d.IsConst {
+			macro = "#let"
+		}
+		fmt.Fprintf(f.writer, "%s%s %s: %s", indentStr, macro, d.Name, d.TypeExpr)
 		if d.DefaultValue != nil {
 			fmt.Fprint(f.writer, " = ")
 			endLine := f.formatValue(d.DefaultValue, indent)
@@ -151,6 +155,15 @@ func (f *Formatter) formatValue(val parser.Value, indent int) int {
 	case *parser.VariableReferenceValue:
 		fmt.Fprint(f.writer, v.Name)
 		return v.Position.Line
+	case *parser.BinaryExpression:
+		f.formatValue(v.Left, indent)
+		fmt.Fprintf(f.writer, " %s ", v.Operator.Value)
+		f.formatValue(v.Right, indent)
+		return v.Position.Line
+	case *parser.UnaryExpression:
+		fmt.Fprint(f.writer, v.Operator.Value)
+		f.formatValue(v.Right, indent)
+		return v.Position.Line
 	case *parser.ArrayValue:
 		fmt.Fprint(f.writer, "{ ")
 		for i, e := range v.Elements {

internal/index/index.go

@@ -5,12 +5,14 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/marte-community/marte-dev-tools/internal/logger"
 	"github.com/marte-community/marte-dev-tools/internal/parser"
 )
 
 type VariableInfo struct {
 	Def  *parser.VariableDefinition
 	File string
+	Doc  string
 }
 
 type ProjectTree struct {
@@ -27,13 +29,14 @@ func (pt *ProjectTree) ScanDirectory(rootPath string) error {
 			return err
 		}
 		if !info.IsDir() && strings.HasSuffix(info.Name(), ".marte") {
+			logger.Printf("indexing: %s [%s]\n", info.Name(), path)
 			content, err := os.ReadFile(path)
 			if err != nil {
 				return err // Or log and continue
 			}
 			p := parser.NewParser(string(content))
-			config, err := p.Parse()
-			if err == nil {
+			config, _ := p.Parse()
+			if config != nil {
 				pt.AddFile(path, config)
 			}
 		}
@@ -232,7 +235,7 @@ func (pt *ProjectTree) populateNode(node *ProjectNode, file string, config *pars
 			pt.indexValue(file, d.Value)
 		case *parser.VariableDefinition:
 			fileFragment.Definitions = append(fileFragment.Definitions, d)
-			node.Variables[d.Name] = VariableInfo{Def: d, File: file}
+			node.Variables[d.Name] = VariableInfo{Def: d, File: file, Doc: doc}
 		case *parser.ObjectNode:
 			fileFragment.Definitions = append(fileFragment.Definitions, d)
 			norm := NormalizeName(d.Name)
@@ -291,7 +294,7 @@ func (pt *ProjectTree) addObjectFragment(node *ProjectNode, file string, obj *pa
 			pt.extractFieldMetadata(node, d)
 		case *parser.VariableDefinition:
 			frag.Definitions = append(frag.Definitions, d)
-			node.Variables[d.Name] = VariableInfo{Def: d, File: file}
+			node.Variables[d.Name] = VariableInfo{Def: d, File: file, Doc: subDoc}
 		case *parser.ObjectNode:
 			frag.Definitions = append(frag.Definitions, d)
 			norm := NormalizeName(d.Name)
@@ -406,6 +409,11 @@ func (pt *ProjectTree) indexValue(file string, val parser.Value) {
 			File:       file,
 			IsVariable: true,
 		})
+	case *parser.BinaryExpression:
+		pt.indexValue(file, v.Left)
+		pt.indexValue(file, v.Right)
+	case *parser.UnaryExpression:
+		pt.indexValue(file, v.Right)
 	case *parser.ArrayValue:
 		for _, elem := range v.Elements {
 			pt.indexValue(file, elem)
@@ -641,7 +649,7 @@ func (pt *ProjectTree) ResolveVariable(ctx *ProjectNode, name string) *VariableI
 		}
 		curr = curr.Parent
 	}
-	if ctx == nil {
+	if pt.Root != nil {
 		if v, ok := pt.Root.Variables[name]; ok {
 			return &v
 		}

internal/lsp/server.go

@@ -97,15 +97,30 @@ type TextDocumentContentChangeEvent struct {
 	Text        string `json:"text"`
 }
 
+type TextDocumentIdentifier struct {
+	URI string `json:"uri"`
+}
+
+type Position struct {
+	Line      int `json:"line"`
+	Character int `json:"character"`
+}
+
+type Range struct {
+	Start Position `json:"start"`
+	End   Position `json:"end"`
+}
+
+type Location struct {
+	URI   string `json:"uri"`
+	Range Range  `json:"range"`
+}
+
 type HoverParams struct {
 	TextDocument TextDocumentIdentifier `json:"textDocument"`
 	Position     Position               `json:"position"`
 }
 
-type TextDocumentIdentifier struct {
-	URI string `json:"uri"`
-}
-
 type DefinitionParams struct {
 	TextDocument TextDocumentIdentifier `json:"textDocument"`
 	Position     Position               `json:"position"`
@@ -121,19 +136,17 @@ type ReferenceContext struct {
 	IncludeDeclaration bool `json:"includeDeclaration"`
 }
 
-type Location struct {
-	URI   string `json:"uri"`
-	Range Range  `json:"range"`
+type InlayHintParams struct {
+	TextDocument TextDocumentIdentifier `json:"textDocument"`
+	Range        Range                  `json:"range"`
 }
 
-type Range struct {
-	Start Position `json:"start"`
-	End   Position `json:"end"`
-}
-
-type Position struct {
-	Line      int `json:"line"`
-	Character int `json:"character"`
+type InlayHint struct {
+	Position     Position `json:"position"`
+	Label        string   `json:"label"`
+	Kind         int      `json:"kind,omitempty"` // 1: Parameter, 2: Type
+	PaddingLeft  bool     `json:"paddingLeft,omitempty"`
+	PaddingRight bool     `json:"paddingRight,omitempty"`
 }
 
 type Hover struct {
@@ -264,6 +277,7 @@ func HandleMessage(msg *JsonRpcMessage) {
 				"referencesProvider":         true,
 				"documentFormattingProvider": true,
 				"renameProvider":             true,
+				"inlayHintProvider":          true,
 				"completionProvider": map[string]any{
 					"triggerCharacters": []string{"=", " ", "@"},
 				},
@@ -325,6 +339,11 @@ func HandleMessage(msg *JsonRpcMessage) {
 		if err := json.Unmarshal(msg.Params, &params); err == nil {
 			respond(msg.ID, HandleRename(params))
 		}
+	case "textDocument/inlayHint":
+		var params InlayHintParams
+		if err := json.Unmarshal(msg.Params, &params); err == nil {
+			respond(msg.ID, HandleInlayHint(params))
+		}
 	}
 }
 
@@ -589,10 +608,19 @@ func HandleHover(params HoverParams) *Hover {
 	} else if res.Field != nil {
 		content = fmt.Sprintf("**Field**: `%s`", res.Field.Name)
 	} else if res.Variable != nil {
-		content = fmt.Sprintf("**Variable**: `%s`\nType: `%s`", res.Variable.Name, res.Variable.TypeExpr)
+		kind := "Variable"
+		if res.Variable.IsConst {
+			kind = "Constant"
+		}
+		content = fmt.Sprintf("**%s**: `%s`\nType: `%s`", kind, res.Variable.Name, res.Variable.TypeExpr)
 		if res.Variable.DefaultValue != nil {
 			content += fmt.Sprintf("\nDefault: `%s`", valueToString(res.Variable.DefaultValue, container))
 		}
+		if info := Tree.ResolveVariable(container, res.Variable.Name); info != nil {
+			if info.Doc != "" {
+				content += "\n\n" + info.Doc
+			}
+		}
 	} else if res.Reference != nil {
 		targetName := "Unresolved"
 		fullInfo := ""
@@ -605,10 +633,19 @@ func HandleHover(params HoverParams) *Hover {
 		} else if res.Reference.TargetVariable != nil {
 			v := res.Reference.TargetVariable
 			targetName = v.Name
-			fullInfo = fmt.Sprintf("**Variable**: `@%s`\nType: `%s`", v.Name, v.TypeExpr)
+			kind := "Variable"
+			if v.IsConst {
+				kind = "Constant"
+			}
+			fullInfo = fmt.Sprintf("**%s**: `@%s`\nType: `%s`", kind, v.Name, v.TypeExpr)
 			if v.DefaultValue != nil {
 				fullInfo += fmt.Sprintf("\nDefault: `%s`", valueToString(v.DefaultValue, container))
 			}
+			if info := Tree.ResolveVariable(container, res.Reference.Name); info != nil {
+				if info.Doc != "" {
+					fullInfo += "\n\n" + info.Doc
+				}
+			}
 		}
 
 		content = fmt.Sprintf("**Reference**: `%s` -> `%s`", res.Reference.Name, targetName)
@@ -678,6 +715,17 @@ func HandleCompletion(params CompletionParams) *CompletionList {
 
 	prefix := lineStr[:col]
 
+	// Case 4: Top-level keywords/macros
+	if strings.HasPrefix(prefix, "#") && !strings.Contains(prefix, " ") {
+		return &CompletionList{
+			Items: []CompletionItem{
+				{Label: "#package", Kind: 14, InsertText: "#package ${1:Project.URI}", InsertTextFormat: 2, Detail: "Project namespace definition"},
+				{Label: "#var", Kind: 14, InsertText: "#var ${1:Name}: ${2:Type} = ${3:DefaultValue}", InsertTextFormat: 2, Detail: "Variable definition"},
+				{Label: "#let", Kind: 14, InsertText: "#let ${1:Name}: ${2:Type} = ${3:Value}", InsertTextFormat: 2, Detail: "Constant variable definition"},
+			},
+		}
+	}
+
 	// Case 3: Variable completion
 	varRegex := regexp.MustCompile(`([@])([a-zA-Z0-9_]*)$`)
 	if matches := varRegex.FindStringSubmatch(prefix); matches != nil {
@@ -1254,6 +1302,17 @@ func HandleReferences(params ReferenceParams) []Location {
 	return locations
 }
 
+func getEvaluatedMetadata(node *index.ProjectNode, key string) string {
+	for _, frag := range node.Fragments {
+		for _, def := range frag.Definitions {
+			if f, ok := def.(*parser.Field); ok && f.Name == key {
+				return valueToString(f.Value, node)
+			}
+		}
+	}
+	return node.Metadata[key]
+}
+
 func formatNodeInfo(node *index.ProjectNode) string {
 	info := ""
 	if class := node.Metadata["Class"]; class != "" {
@@ -1262,8 +1321,8 @@ func formatNodeInfo(node *index.ProjectNode) string {
 		info = fmt.Sprintf("`%s`\n\n", node.RealName)
 	}
 	// Check if it's a Signal (has Type or DataSource)
-	typ := node.Metadata["Type"]
-	ds := node.Metadata["DataSource"]
+	typ := getEvaluatedMetadata(node, "Type")
+	ds := getEvaluatedMetadata(node, "DataSource")
 
 	if ds == "" {
 		if node.Parent != nil && node.Parent.Name == "Signals" {
@@ -1283,8 +1342,8 @@ func formatNodeInfo(node *index.ProjectNode) string {
 		}
 
 		// Size
-		dims := node.Metadata["NumberOfDimensions"]
-		elems := node.Metadata["NumberOfElements"]
+		dims := getEvaluatedMetadata(node, "NumberOfDimensions")
+		elems := getEvaluatedMetadata(node, "NumberOfElements")
 		if dims != "" || elems != "" {
 			sigInfo += fmt.Sprintf("**Size**: `[%s]`, `%s` dims ", elems, dims)
 		}
@@ -1696,10 +1755,15 @@ func suggestVariables(container *index.ProjectNode) *CompletionList {
 					doc = fmt.Sprintf("Default: %s", valueToString(info.Def.DefaultValue, container))
 				}
 
+				kind := "Variable"
+				if info.Def.IsConst {
+					kind = "Constant"
+				}
+
 				items = append(items, CompletionItem{
 					Label:         name,
 					Kind:          6, // Variable
-					Detail:        fmt.Sprintf("Variable (%s)", info.Def.TypeExpr),
+					Detail:        fmt.Sprintf("%s (%s)", kind, info.Def.TypeExpr),
 					Documentation: doc,
 				})
 			}
@@ -1901,3 +1965,161 @@ func computeUnary(op parser.Token, val parser.Value) parser.Value {
 	}
 	return val
 }
+
+func isComplexValue(val parser.Value) bool {
+	switch val.(type) {
+	case *parser.BinaryExpression, *parser.UnaryExpression, *parser.VariableReferenceValue:
+		return true
+	}
+	return false
+}
+
+func HandleInlayHint(params InlayHintParams) []InlayHint {
+	path := uriToPath(params.TextDocument.URI)
+	var hints []InlayHint
+	seenPositions := make(map[Position]bool)
+
+	addHint := func(h InlayHint) {
+		if !seenPositions[h.Position] {
+			hints = append(hints, h)
+			seenPositions[h.Position] = true
+		}
+	}
+
+	Tree.Walk(func(node *index.ProjectNode) {
+		for _, frag := range node.Fragments {
+			if frag.File != path {
+				continue
+			}
+
+			// Signal Name Hint (::TYPE[SIZE])
+			if node.Parent != nil && (node.Parent.Name == "InputSignals" || node.Parent.Name == "OutputSignals") {
+				typ := getEvaluatedMetadata(node, "Type")
+				elems := getEvaluatedMetadata(node, "NumberOfElements")
+				dims := getEvaluatedMetadata(node, "NumberOfDimensions")
+
+				if typ == "" && node.Target != nil {
+					typ = node.Target.Metadata["Type"]
+					if elems == "" {
+						elems = node.Target.Metadata["NumberOfElements"]
+					}
+					if dims == "" {
+						dims = node.Target.Metadata["NumberOfDimensions"]
+					}
+				}
+
+				if typ != "" {
+					if elems == "" {
+						elems = "1"
+					}
+					if dims == "" {
+						dims = "1"
+					}
+					label := fmt.Sprintf("::%s[%sx%s]", typ, elems, dims)
+
+					pos := frag.ObjectPos
+					addHint(InlayHint{
+						Position: Position{Line: pos.Line - 1, Character: pos.Column - 1 + len(node.RealName)},
+						Label:    label,
+						Kind:     2, // Type
+					})
+				}
+			}
+
+			// Field-based hints (DataSource class and Expression evaluation)
+			for _, def := range frag.Definitions {
+				if f, ok := def.(*parser.Field); ok {
+					// DataSource Class Hint
+					if f.Name == "DataSource" && (node.Parent != nil && (node.Parent.Name == "InputSignals" || node.Parent.Name == "OutputSignals")) {
+						dsName := valueToString(f.Value, node)
+						dsNode := Tree.ResolveName(node, dsName, isDataSource)
+						if dsNode != nil {
+							cls := dsNode.Metadata["Class"]
+							if cls != "" {
+								addHint(InlayHint{
+									Position: Position{Line: f.Position.Line - 1, Character: f.Position.Column - 1 + len(f.Name) + 3}, // "DataSource = "
+									Label:    cls + "::",
+									Kind:     1, // Parameter
+								})
+							}
+						}
+					}
+
+					// Expression Evaluation Hint
+					if isComplexValue(f.Value) {
+						res := valueToString(f.Value, node)
+						if res != "" {
+							uri := params.TextDocument.URI
+							text, ok := Documents[uri]
+							if ok {
+								lines := strings.Split(text, "\n")
+								lineIdx := f.Position.Line - 1
+								if lineIdx >= 0 && lineIdx < len(lines) {
+									line := lines[lineIdx]
+									addHint(InlayHint{
+										Position: Position{Line: lineIdx, Character: len(line)},
+										Label:    " => " + res,
+										Kind:     2, // Type/Value
+									})
+								}
+							}
+						}
+					}
+				} else if v, ok := def.(*parser.VariableDefinition); ok {
+					// Expression Evaluation Hint for #let/#var
+					if v.DefaultValue != nil && isComplexValue(v.DefaultValue) {
+						res := valueToString(v.DefaultValue, node)
+						if res != "" {
+							uri := params.TextDocument.URI
+							text, ok := Documents[uri]
+							if ok {
+								lines := strings.Split(text, "\n")
+								lineIdx := v.Position.Line - 1
+								if lineIdx >= 0 && lineIdx < len(lines) {
+									line := lines[lineIdx]
+									addHint(InlayHint{
+										Position: Position{Line: lineIdx, Character: len(line)},
+										Label:    " => " + res,
+										Kind:     2,
+									})
+								}
+							}
+						}
+					}
+				}
+			}
+		}
+	})
+
+	// Add logic for general object references
+	for _, ref := range Tree.References {
+		if ref.File != path {
+			continue
+		}
+		if ref.Target != nil {
+			cls := ref.Target.Metadata["Class"]
+			if cls != "" {
+				addHint(InlayHint{
+					Position: Position{Line: ref.Position.Line - 1, Character: ref.Position.Column - 1},
+					Label:    cls + "::",
+					Kind:     1, // Parameter
+				})
+			}
+		} else if ref.IsVariable {
+			// Variable reference evaluation hint: @VAR(=> VALUE)
+			container := Tree.GetNodeContaining(ref.File, ref.Position)
+			if info := Tree.ResolveVariable(container, ref.Name); info != nil && info.Def.DefaultValue != nil {
+				val := valueToString(info.Def.DefaultValue, container)
+				if val != "" {
+					addHint(InlayHint{
+						Position: Position{Line: ref.Position.Line - 1, Character: ref.Position.Column - 1 + len(ref.Name) + 1},
+						Label:    "(=> " + val + ")",
+						Kind:     2,
+					})
+				}
+			}
+		}
+	}
+
+	return hints
+}

internal/parser/ast.go

@@ -131,6 +131,7 @@ type VariableDefinition struct {
 	Name         string
 	TypeExpr     string
 	DefaultValue Value
+	IsConst      bool
 }
 
 func (v *VariableDefinition) Pos() Position { return v.Position }

internal/parser/lexer.go

@@ -20,6 +20,7 @@ const (
 	TokenBool
 	TokenPackage
 	TokenPragma
+	TokenLet
 	TokenComment
 	TokenDocstring
 	TokenComma
@@ -236,7 +237,21 @@ func (l *Lexer) lexString() Token {
 }
 
 func (l *Lexer) lexNumber() Token {
-	// Consume initial digits (already started)
+	// Check for hex or binary prefix if we started with '0'
+	if l.input[l.start:l.pos] == "0" {
+		switch l.peek() {
+		case 'x', 'X':
+			l.next()
+			l.lexHexDigits()
+			return l.emit(TokenNumber)
+		case 'b', 'B':
+			l.next()
+			l.lexBinaryDigits()
+			return l.emit(TokenNumber)
+		}
+	}
+
+	// Consume remaining digits
 	l.lexDigits()
 
 	if l.peek() == '.' {
@@ -255,6 +270,28 @@ func (l *Lexer) lexNumber() Token {
 	return l.emit(TokenNumber)
 }
 
+func (l *Lexer) lexHexDigits() {
+	for {
+		r := l.peek()
+		if unicode.IsDigit(r) || (r >= 'a' && r <= 'f') || (r >= 'A' && r <= 'F') {
+			l.next()
+		} else {
+			break
+		}
+	}
+}
+
+func (l *Lexer) lexBinaryDigits() {
+	for {
+		r := l.peek()
+		if r == '0' || r == '1' {
+			l.next()
+		} else {
+			break
+		}
+	}
+}
+
 func (l *Lexer) lexDigits() {
 	for unicode.IsDigit(l.peek()) {
 		l.next()
@@ -321,6 +358,9 @@ func (l *Lexer) lexHashIdentifier() Token {
 	if val == "#package" {
 		return l.lexUntilNewline(TokenPackage)
 	}
+	if val == "#let" {
+		return l.emit(TokenLet)
+	}
 	return l.emit(TokenIdentifier)
 }
 

internal/parser/parser.go

@@ -99,6 +99,8 @@ func (p *Parser) Parse() (*Configuration, error) {
 func (p *Parser) parseDefinition() (Definition, bool) {
 	tok := p.next()
 	switch tok.Type {
+	case TokenLet:
+		return p.parseLet(tok)
 	case TokenIdentifier:
 		name := tok.Value
 		if name == "#var" {
@@ -286,7 +288,11 @@ func (p *Parser) parseAtom() (Value, bool) {
 		}, true
 
 	case TokenNumber:
-		if strings.Contains(tok.Value, ".") || strings.Contains(tok.Value, "e") {
+		isFloat := (strings.Contains(tok.Value, ".") || strings.Contains(tok.Value, "e") || strings.Contains(tok.Value, "E")) &&
+			!strings.HasPrefix(tok.Value, "0x") && !strings.HasPrefix(tok.Value, "0X") &&
+			!strings.HasPrefix(tok.Value, "0b") && !strings.HasPrefix(tok.Value, "0B")
+
+		if isFloat {
 			f, _ := strconv.ParseFloat(tok.Value, 64)
 			return &FloatValue{Position: tok.Position, Value: f, Raw: tok.Value}, true
 		}
@@ -409,6 +415,58 @@ func (p *Parser) parseVariableDefinition(startTok Token) (Definition, bool) {
 	}, true
 }
 
+func (p *Parser) parseLet(startTok Token) (Definition, bool) {
+	nameTok := p.next()
+	if nameTok.Type != TokenIdentifier {
+		p.addError(nameTok.Position, "expected constant name")
+		return nil, false
+	}
+
+	if p.next().Type != TokenColon {
+		p.addError(nameTok.Position, "expected :")
+		return nil, false
+	}
+
+	var typeTokens []Token
+	startLine := nameTok.Position.Line
+
+	for {
+		t := p.peek()
+		if t.Position.Line > startLine || t.Type == TokenEOF {
+			break
+		}
+		if t.Type == TokenEqual {
+			break
+		}
+		typeTokens = append(typeTokens, p.next())
+	}
+
+	typeExpr := ""
+	for _, t := range typeTokens {
+		typeExpr += t.Value + " "
+	}
+
+	var defVal Value
+	if p.next().Type != TokenEqual {
+		p.addError(nameTok.Position, "expected =")
+		return nil, false
+	}
+	val, ok := p.parseValue()
+	if ok {
+		defVal = val
+	} else {
+		return nil, false
+	}
+
+	return &VariableDefinition{
+		Position:     startTok.Position,
+		Name:         nameTok.Value,
+		TypeExpr:     strings.TrimSpace(typeExpr),
+		DefaultValue: defVal,
+		IsConst:      true,
+	}, true
+}
+
 func (p *Parser) Errors() []error {
 	return p.errors
 }

internal/validator/validator.go

@@ -577,9 +577,20 @@ func (v *Validator) validateGAMSignal(gamNode, signalNode *index.ProjectNode, di
 	}
 }
 
+func (v *Validator) getEvaluatedMetadata(node *index.ProjectNode, key string) string {
+	for _, frag := range node.Fragments {
+		for _, def := range frag.Definitions {
+			if f, ok := def.(*parser.Field); ok && f.Name == key {
+				return v.getFieldValue(f, node)
+			}
+		}
+	}
+	return node.Metadata[key]
+}
+
 func (v *Validator) checkSignalProperty(gamSig, dsSig *index.ProjectNode, prop string) {
-	gamVal := gamSig.Metadata[prop]
-	dsVal := dsSig.Metadata[prop]
+	gamVal := v.getEvaluatedMetadata(gamSig, prop)
+	dsVal := v.getEvaluatedMetadata(dsSig, prop)
 
 	if gamVal == "" {
 		return
@@ -646,26 +657,11 @@ func (v *Validator) getFields(node *index.ProjectNode) map[string][]*parser.Fiel
 }
 
 func (v *Validator) getFieldValue(f *parser.Field, ctx *index.ProjectNode) string {
-	switch val := f.Value.(type) {
-	case *parser.StringValue:
-		return val.Value
-	case *parser.ReferenceValue:
-		return val.Value
-	case *parser.IntValue:
-		return val.Raw
-	case *parser.FloatValue:
-		return val.Raw
-	case *parser.BoolValue:
-		return strconv.FormatBool(val.Value)
-	case *parser.VariableReferenceValue:
-		name := strings.TrimPrefix(val.Name, "@")
-		if info := v.Tree.ResolveVariable(ctx, name); info != nil {
-			if info.Def.DefaultValue != nil {
-				return v.getFieldValue(&parser.Field{Value: info.Def.DefaultValue}, ctx)
-			}
-		}
+	res := v.valueToInterface(f.Value, ctx)
+	if res == nil {
+		return ""
 	}
-	return ""
+	return fmt.Sprintf("%v", res)
 }
 
 func (v *Validator) resolveReference(name string, ctx *index.ProjectNode, predicate func(*index.ProjectNode) bool) *index.ProjectNode {
@@ -1328,34 +1324,57 @@ func (v *Validator) CheckVariables() {
 	ctx := v.Schema.Context
 
 	checkNodeVars := func(node *index.ProjectNode) {
-		for _, info := range node.Variables {
-			def := info.Def
+		seen := make(map[string]parser.Position)
+		for _, frag := range node.Fragments {
+			for _, def := range frag.Definitions {
+				if vdef, ok := def.(*parser.VariableDefinition); ok {
+					if prevPos, exists := seen[vdef.Name]; exists {
+						v.Diagnostics = append(v.Diagnostics, Diagnostic{
+							Level:    LevelError,
+							Message:  fmt.Sprintf("Duplicate variable definition: '%s' was already defined at %d:%d", vdef.Name, prevPos.Line, prevPos.Column),
+							Position: vdef.Position,
+							File:     frag.File,
+						})
+					}
+					seen[vdef.Name] = vdef.Position
 
-			// Compile Type
-			typeVal := ctx.CompileString(def.TypeExpr)
-			if typeVal.Err() != nil {
-				v.Diagnostics = append(v.Diagnostics, Diagnostic{
-					Level:    LevelError,
-					Message:  fmt.Sprintf("Invalid type expression for variable '%s': %v", def.Name, typeVal.Err()),
-					Position: def.Position,
-					File:     info.File,
-				})
-				continue
-			}
+					if vdef.IsConst && vdef.DefaultValue == nil {
+						v.Diagnostics = append(v.Diagnostics, Diagnostic{
+							Level:    LevelError,
+							Message:  fmt.Sprintf("Constant variable '%s' must have an initial value", vdef.Name),
+							Position: vdef.Position,
+							File:     frag.File,
+						})
+						continue
+					}
 
-			if def.DefaultValue != nil {
-				valInterface := v.valueToInterface(def.DefaultValue, node)
-				valVal := ctx.Encode(valInterface)
+					// Compile Type
+					typeVal := ctx.CompileString(vdef.TypeExpr)
+					if typeVal.Err() != nil {
+						v.Diagnostics = append(v.Diagnostics, Diagnostic{
+							Level:    LevelError,
+							Message:  fmt.Sprintf("Invalid type expression for variable '%s': %v", vdef.Name, typeVal.Err()),
+							Position: vdef.Position,
+							File:     frag.File,
+						})
+						continue
+					}
 
-				// Unify
-				res := typeVal.Unify(valVal)
-				if err := res.Validate(cue.Concrete(true)); err != nil {
-					v.Diagnostics = append(v.Diagnostics, Diagnostic{
-						Level:    LevelError,
-						Message:  fmt.Sprintf("Variable '%s' value mismatch: %v", def.Name, err),
-						Position: def.Position,
-						File:     info.File,
-					})
+					if vdef.DefaultValue != nil {
+						valInterface := v.valueToInterface(vdef.DefaultValue, node)
+						valVal := ctx.Encode(valInterface)
+
+						// Unify
+						res := typeVal.Unify(valVal)
+						if err := res.Validate(cue.Concrete(true)); err != nil {
+							v.Diagnostics = append(v.Diagnostics, Diagnostic{
+								Level:    LevelError,
+								Message:  fmt.Sprintf("Variable '%s' value mismatch: %v", vdef.Name, err),
+								Position: vdef.Position,
+								File:     frag.File,
+							})
+						}
+					}
 				}
 			}
 		}

specification.md

@@ -42,6 +42,10 @@ The LSP server should provide the following capabilities:
 - **Rename Symbol**: Rename an object, field, or reference across the entire project scope.
   - Supports renaming of Definitions (`+Name` or `Name`), preserving any modifiers (`+`/`$`).
   - Updates all references to the renamed symbol, including qualified references (e.g., `Pkg.Name`).
+- **Inlay Hints**: Provide real-time contextual information inline.
+  - **Signal Metadata**: Displays `::TYPE[ELEMENTSxDIMENSIONS]` next to signal names.
+  - **Object Class**: Displays `CLASS::` before object references.
+  - **Evaluation**: Displays results of expressions (` => RESULT`) and variable references (`(=> VALUE)`).
 - **Code Snippets**: Provide snippets for common patterns (e.g., `+Object = { ... }`).
 - **Formatting**: Format the document using the same rules and engine as the `fmt` command.
 
@@ -71,22 +75,31 @@ The LSP server should provide the following capabilities:
 ### Grammar
 
 - `comment` : `//.*`
-- `configuration`: `definition+`
+- `configuration`: `(definition | macro)+`
 - `definition`: `field = value | node = subnode`
+- `macro`: `package | variable | constant`
 - `field`: `[a-zA-Z][a-zA-Z0-9_\-]*`
 - `node`: `[+$][a-zA-Z][a-zA-Z0-9_\-]*`
-- `subnode`: `{ definition+ }`
-- `value`: `string|int|float|bool|reference|array`
+- `subnode`: `{ (definition | macro)+ }`
+- `value`: `expression`
+- `expression`: `atom | binary_expr | unary_expr`
+- `atom`: `string | int | float | bool | reference | array | "(" expression ")"`
+- `binary_expr`: `expression operator expression`
+- `unary_expr`: `unary_operator expression`
+- `operator`: `+ | - | * | / | % | & | | | ^ | ..`
+- `unary_operator`: `- | !`
 - `int`: `/-?[0-9]+|0b[01]+|0x[0-9a-fA-F]+`
-- `float`: `-?[0-9]+\.[0-9]+|-?[0-9]+\.?[0-9]*e\-?[0-9]+`
+- `float`: `-?[0-9]+\.[0-9]+|-?[0-9]+\.?[0-9]*[eE][+-]?[0-9]+`
 - `bool`: `true|false`
 - `string`: `".*"`
-- `reference` : `string|.*`
-- `array`: `{ value }`
+- `reference` : `[a-zA-Z][a-zA-Z0-9_\-\.]* | @[a-zA-Z0-9_]+ | $[a-zA-Z0-9_]+`
+- `array`: `{ (value | ",")* }`
 
 #### Extended grammar
 
 - `package` : `#package URI`
+- `variable`: `#var NAME: TYPE [= expression]`
+- `constant`: `#let NAME: TYPE = expression`
 - `URI`: `PROJECT | PROJECT.PRJ_SUB_URI`
 - `PRJ_SUB_URI`: `NODE | NODE.PRJ_SUB_URI`
 - `docstring` : `//#.*`
@@ -97,13 +110,17 @@ The LSP server should provide the following capabilities:
 - **Nodes (`+` / `$`)**: The prefixes `+` and `$` indicate that the node represents an object.
   - **Constraint**: These nodes _must_ contain a field named `Class` within their subnode definition (across all files where the node is defined).
 - **Signals**: Signals are considered nodes but **not** objects. They do not require a `Class` field.
+- **Variables (`#var`)**: Define overrideable parameters. Can be overridden via CLI (`-vVAR=VAL`).
+- **Constants (`#let`)**: Define fixed parameters. **Cannot** be overridden externally. Must have an initial value.
+- **Expressions**: Evaluated during build and displayed evaluated in LSP hover documentation.
+- **Docstrings (`//#`)**: Associated with the following definition (Node, Field, Variable, or Constant).
 - **Pragmas (`//!`)**: Used to suppress specific diagnostics. The developer can use these to explain why a rule is being ignored. Supported pragmas:
   - `//!unused: REASON` or `//!ignore(unused): REASON` - Suppress "Unused GAM" or "Unused Signal" warnings.
   - `//!implicit: REASON` or `//!ignore(implicit): REASON` - Suppress "Implicitly Defined Signal" warnings.
-  - `//!allow(WARNING_TYPE): REASON` or `//!ignore(WARNING_TYPE): REASON` - Global suppression for a specific warning type across the whole project (supported: `unused`, `implicit`).
+  - `//!allow(WARNING_TYPE): REASON` or `//!ignore(WARNING_TYPE): REASON` - Global suppression for a specific warning type across the whole project (supported: `unused`, `implicit`, `not_consumed`, `not_produced`).
   - `//!cast(DEF_TYPE, CUR_TYPE): REASON` - Suppress "Type Inconsistency" errors if types match.
-- **Structure**: A configuration is composed by one or more definitions.
-- **Strictness**: Any content that is not a valid comment (or pragma/docstring) or a valid definition (Field, Node, or Object) is **not allowed** and must generate a parsing error.
+- **Structure**: A configuration is composed by one or more definitions or macros.
+- **Strictness**: Any content that is not a valid comment (or pragma/docstring) or a valid definition/macro is **not allowed** and must generate a parsing error.
 
 ### Core MARTe Classes
 
@@ -124,6 +141,7 @@ MARTe configurations typically involve several main categories of objects:
     - All signal definitions **must** include a `Type` field with a valid value.
     - **Size Information**: Signals can optionally include `NumberOfDimensions` and `NumberOfElements` fields. If not explicitly defined, these default to `1`.
     - **Property Matching**: Signal references in GAMs must match the properties (`Type`, `NumberOfElements`, `NumberOfDimensions`) of the defined signal in the `DataSource`.
+    - **Consistency**: Implicit signals used across different GAMs must share the same `Type` and size properties.
     - **Extensibility**: Signal definitions can include additional fields as required by the specific application context.
 - **Signal Reference Syntax**:
   - Signals are referenced or defined in `InputSignals` or `OutputSignals` sub-nodes using one of the following formats:
@@ -145,6 +163,7 @@ MARTe configurations typically involve several main categories of objects:
         ```
         In this case, `Alias` points to the DataSource signal name.
   - **Implicit Definition Constraint**: If a signal is implicitly defined within a GAM, the `Type` field **must** be present in the reference block to define the signal's properties.
+- **Renaming**: Renaming a signal (explicit or implicit) via LSP updates all its usages across all GAMs and DataSources in the project. Local aliases (`Alias = Name`) are preserved while their targets are updated.
 - **Directionality**: DataSources and their signals are directional:
   - `Input` (IN): Only providing data. Signals can only be used in `InputSignals`.
   - `Output` (OUT): Only receiving data. Signals can only be used in `OutputSignals`.
@@ -155,9 +174,11 @@ MARTe configurations typically involve several main categories of objects:
 
 The tool must build an index of the configuration to support LSP features and validations:
 
+- **Recursive Indexing**: All `.marte` files in the project root and subdirectories are indexed automatically.
 - **GAMs**: Referenced in `$APPLICATION.States.$STATE_NAME.Threads.$THREAD_NAME.Functions` (where `$APPLICATION` is a `RealTimeApplication` node).
 - **Signals**: Referenced within the `InputSignals` and `OutputSignals` sub-nodes of a GAM.
 - **DataSources**: Referenced within the `DataSource` field of a signal reference/definition.
+- **Variables/Constants**: Referenced via `@NAME` or `$NAME` in expressions.
 - **General References**: Objects can also be referenced in other fields (e.g., as targets for messages).
 
 ### Validation Rules

test/advanced_numbers_test.go

@@ -0,0 +1,78 @@
+package integration
+
+import (
+	"testing"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+	"github.com/marte-community/marte-dev-tools/internal/formatter"
+	"bytes"
+)
+
+func TestAdvancedNumbers(t *testing.T) {
+	content := `
+Hex = 0xFF
+HexLower = 0xee
+Binary = 0b1011
+Decimal = 123
+Scientific = 1e-3
+`
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatalf("Parse failed: %v", err)
+	}
+
+	// Verify values
+	foundHex := false
+	foundHexLower := false
+	foundBinary := false
+	for _, def := range cfg.Definitions {
+		if f, ok := def.(*parser.Field); ok {
+			if f.Name == "Hex" {
+				if v, ok := f.Value.(*parser.IntValue); ok {
+					if v.Value != 255 {
+						t.Errorf("Expected 255 for Hex, got %d", v.Value)
+					}
+					foundHex = true
+				}
+			}
+			if f.Name == "HexLower" {
+				if v, ok := f.Value.(*parser.IntValue); ok {
+					if v.Value != 238 {
+						t.Errorf("Expected 238 for HexLower, got %d", v.Value)
+					}
+					foundHexLower = true
+				} else {
+					t.Errorf("HexLower was parsed as %T, expected *parser.IntValue", f.Value)
+				}
+			}
+			if f.Name == "Binary" {
+				if v, ok := f.Value.(*parser.IntValue); ok {
+					if v.Value == 11 {
+						foundBinary = true
+					}
+				}
+			}
+		}
+	}
+	if !foundHex { t.Error("Hex field not found") }
+	if !foundHexLower { t.Error("HexLower field not found") }
+	if !foundBinary { t.Error("Binary field not found") }
+
+	// Verify formatting
+	var buf bytes.Buffer
+	formatter.Format(cfg, &buf)
+	formatted := buf.String()
+	if !contains(formatted, "Hex = 0xFF") {
+		t.Errorf("Formatted content missing Hex = 0xFF:\n%s", formatted)
+	}
+	if !contains(formatted, "HexLower = 0xee") {
+		t.Errorf("Formatted content missing HexLower = 0xee:\n%s", formatted)
+	}
+	if !contains(formatted, "Binary = 0b1011") {
+		t.Errorf("Formatted content missing Binary = 0b1011:\n%s", formatted)
+	}
+}
+
+func contains(s, substr string) bool {
+	return bytes.Contains([]byte(s), []byte(substr))
+}

test/evaluated_signal_props_test.go

@@ -0,0 +1,88 @@
+package integration
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+	"github.com/marte-community/marte-dev-tools/internal/validator"
+)
+
+func TestEvaluatedSignalProperties(t *testing.T) {
+	content := `
+#let N: uint32 = 10
++DS = {
+    Class = FileReader
+    Filename = "test.bin"
+    Signals = {
+        Sig1 = { Type = uint32 NumberOfElements = @N }
+    }
+}
++GAM = {
+    Class = IOGAM
+    InputSignals = {
+        Sig1 = { DataSource = DS Type = uint32 NumberOfElements = 10 }
+    }
+}
+`
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tree := index.NewProjectTree()
+	tree.AddFile("test.marte", cfg)
+	tree.ResolveReferences()
+
+	v := validator.NewValidator(tree, ".")
+	v.ValidateProject()
+
+	// There should be no errors because @N evaluates to 10
+	for _, d := range v.Diagnostics {
+		if d.Level == validator.LevelError {
+			t.Errorf("Unexpected error: %s", d.Message)
+		}
+	}
+
+	// Test mismatch with expression
+	contentErr := `
+#let N: uint32 = 10
++DS = {
+    Class = FileReader
+    Filename = "test.bin"
+    Signals = {
+        Sig1 = { Type = uint32 NumberOfElements = @N + 5 }
+    }
+}
++GAM = {
+    Class = IOGAM
+    InputSignals = {
+        Sig1 = { DataSource = DS Type = uint32 NumberOfElements = 10 }
+    }
+}
+`
+	p2 := parser.NewParser(contentErr)
+	cfg2, _ := p2.Parse()
+	tree2 := index.NewProjectTree()
+	tree2.AddFile("test_err.marte", cfg2)
+	tree2.ResolveReferences()
+
+	v2 := validator.NewValidator(tree2, ".")
+	v2.ValidateProject()
+
+	found := false
+	for _, d := range v2.Diagnostics {
+		if strings.Contains(d.Message, "property 'NumberOfElements' mismatch") {
+			found = true
+			if !strings.Contains(d.Message, "defined '15'") {
+				t.Errorf("Expected defined '15', got message: %s", d.Message)
+			}
+			break
+		}
+	}
+	if !found {
+		t.Error("Expected property mismatch error for @N + 5")
+	}
+}

test/let_macro_test.go

@@ -0,0 +1,125 @@
+package integration
+
+import (
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/builder"
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+	"github.com/marte-community/marte-dev-tools/internal/validator"
+)
+
+func TestLetMacroFull(t *testing.T) {
+	content := `
+//# My documentation
+#let MyConst: uint32 = 10 + 20
++Obj = {
+    Value = @MyConst
+}
+`
+	tmpFile, _ := os.CreateTemp("", "let_*.marte")
+	defer os.Remove(tmpFile.Name())
+	os.WriteFile(tmpFile.Name(), []byte(content), 0644)
+
+	// 1. Test Parsing & Indexing
+	p := parser.NewParser(content)
+	cfg, err := p.Parse()
+	if err != nil {
+		t.Fatalf("Parse failed: %v", err)
+	}
+
+	tree := index.NewProjectTree()
+	tree.AddFile(tmpFile.Name(), cfg)
+
+	vars := tree.Root.Variables
+	if iso, ok := tree.IsolatedFiles[tmpFile.Name()]; ok {
+		vars = iso.Variables
+	}
+
+	info, ok := vars["MyConst"]
+	if !ok || !info.Def.IsConst {
+		t.Fatal("#let variable not indexed correctly as Const")
+	}
+	if info.Doc != "My documentation" {
+		t.Errorf("Expected doc 'My documentation', got '%s'", info.Doc)
+	}
+
+	// 2. Test Builder Evaluation
+	out, _ := os.CreateTemp("", "let_out.cfg")
+	defer os.Remove(out.Name())
+
+	b := builder.NewBuilder([]string{tmpFile.Name()}, nil)
+	if err := b.Build(out); err != nil {
+		t.Fatalf("Build failed: %v", err)
+	}
+
+	outContent, _ := os.ReadFile(out.Name())
+	if !strings.Contains(string(outContent), "Value = 30") {
+		t.Errorf("Expected Value = 30 (evaluated @MyConst), got:\n%s", string(outContent))
+	}
+
+	// 3. Test Override Protection
+	out2, _ := os.CreateTemp("", "let_out2.cfg")
+	defer os.Remove(out2.Name())
+
+	b2 := builder.NewBuilder([]string{tmpFile.Name()}, map[string]string{"MyConst": "100"})
+	if err := b2.Build(out2); err != nil {
+		t.Fatalf("Build failed: %v", err)
+	}
+
+	outContent2, _ := os.ReadFile(out2.Name())
+	if !strings.Contains(string(outContent2), "Value = 30") {
+		t.Errorf("Constant was overridden! Expected 30, got:\n%s", string(outContent2))
+	}
+
+	// 4. Test Validator (Mandatory Value)
+	contentErr := "#let BadConst: uint32"
+	p2 := parser.NewParser(contentErr)
+	cfg2, err2 := p2.Parse()
+	// Parser might fail if = is missing?
+	// parseLet expects =.
+	if err2 == nil {
+		// If parser didn't fail (maybe it was partial), validator should catch it
+		tree2 := index.NewProjectTree()
+		tree2.AddFile("err.marte", cfg2)
+		v := validator.NewValidator(tree2, ".")
+		v.ValidateProject()
+
+		found := false
+		for _, d := range v.Diagnostics {
+			if strings.Contains(d.Message, "must have an initial value") {
+				found = true
+				break
+			}
+		}
+		if !found && cfg2 != nil {
+			// If p2.Parse() failed and added error to p2.errors, it's also fine.
+			// But check if it reached validator.
+		}
+	}
+
+	// 5. Test Duplicate Detection
+	contentDup := `
+#let MyConst: uint32 = 10
+#var MyConst: uint32 = 20
+`
+	p3 := parser.NewParser(contentDup)
+	cfg3, _ := p3.Parse()
+	tree3 := index.NewProjectTree()
+	tree3.AddFile("dup.marte", cfg3)
+	v3 := validator.NewValidator(tree3, ".")
+	v3.ValidateProject()
+
+	foundDup := false
+	for _, d := range v3.Diagnostics {
+		if strings.Contains(d.Message, "Duplicate variable definition") {
+			foundDup = true
+			break
+		}
+	}
+	if !foundDup {
+		t.Error("Expected duplicate variable definition error")
+	}
+}

test/lsp_inlay_hint_test.go

@@ -0,0 +1,108 @@
+package integration
+
+import (
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+	"github.com/marte-community/marte-dev-tools/internal/parser"
+	"github.com/marte-community/marte-dev-tools/internal/validator"
+)
+
+func TestLSPInlayHint(t *testing.T) {
+	// Setup
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+
+	content := `
+#let N : int= 10 + 5
++DS = {
+    Class = FileReader
+    Signals = {
+        Sig1 = { Type = uint32 NumberOfElements = 10 }
+    }
+}
++GAM = {
+    Class = IOGAM
+    Expr = 10 + 20
+    InputSignals = {
+        Sig1 = { DataSource = DS }
+    }
+}
++Other = {
+    Class = Controller
+    Ref = DS
+    VarRef = @N + 1
+}
+`
+	uri := "file://inlay.marte"
+	lsp.Documents[uri] = content
+	p := parser.NewParser(content)
+	cfg, _ := p.Parse()
+	lsp.Tree.AddFile("inlay.marte", cfg)
+	lsp.Tree.ResolveReferences()
+
+	v := validator.NewValidator(lsp.Tree, ".")
+	v.ValidateProject()
+
+	params := lsp.InlayHintParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: uri},
+		Range: lsp.Range{
+			Start: lsp.Position{Line: 0, Character: 0},
+			End:   lsp.Position{Line: 20, Character: 0},
+		},
+	}
+
+	res := lsp.HandleInlayHint(params)
+	if len(res) == 0 {
+		t.Fatal("Expected inlay hints, got 0")
+	}
+
+	foundTypeHint := false
+	foundDSClassHint := false
+	foundGeneralRefHint := false
+	foundExprHint := false
+	foundVarRefHint := false
+	foundLetHint := false
+
+	for _, hint := range res {
+		t.Logf("Hint: '%s' at Line %d, Col %d", hint.Label, hint.Position.Line, hint.Position.Character)
+		if hint.Label == "::uint32[10x1]" {
+			foundTypeHint = true
+		}
+		if hint.Label == "FileReader::" && hint.Position.Line == 12 { // Sig1 line (DS)
+			foundDSClassHint = true
+		}
+		if hint.Label == "FileReader::" && hint.Position.Line == 17 { // Ref = DS line
+			foundGeneralRefHint = true
+		}
+		if hint.Label == " => 30" {
+			foundExprHint = true
+		}
+		if hint.Label == "(=> 15)" {
+			foundVarRefHint = true
+		}
+		if hint.Label == " => 15" && hint.Position.Line == 1 { // #let N line
+			foundLetHint = true
+		}
+	}
+
+	if !foundTypeHint {
+		t.Error("Did not find signal type/size hint")
+	}
+	if !foundDSClassHint {
+		t.Error("Did not find DataSource class hint")
+	}
+	if !foundGeneralRefHint {
+		t.Error("Did not find general object reference hint")
+	}
+	if !foundExprHint {
+		t.Error("Did not find expression evaluation hint")
+	}
+	if !foundVarRefHint {
+		t.Error("Did not find variable reference evaluation hint")
+	}
+	if !foundLetHint {
+		t.Error("Did not find #let expression evaluation hint")
+	}
+}

test/lsp_recursive_index_test.go

@@ -0,0 +1,88 @@
+package integration
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+)
+
+func TestLSPRecursiveIndexing(t *testing.T) {
+	// Setup directory structure
+	rootDir, err := os.MkdirTemp("", "lsp_recursive")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(rootDir)
+
+	// root/main.marte
+	mainContent := `
+#package App
++Main = {
+    Ref = SubComp
+}
+`
+	if err := os.WriteFile(filepath.Join(rootDir, "main.marte"), []byte(mainContent), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	// root/subdir/sub.marte
+	subDir := filepath.Join(rootDir, "subdir")
+	if err := os.Mkdir(subDir, 0755); err != nil {
+		t.Fatal(err)
+	}
+	subContent := `
+#package App
++SubComp = { Class = Component }
+`
+	if err := os.WriteFile(filepath.Join(subDir, "sub.marte"), []byte(subContent), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	// Initialize LSP
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+
+	// Simulate ScanDirectory
+	if err := lsp.Tree.ScanDirectory(rootDir); err != nil {
+		t.Fatalf("ScanDirectory failed: %v", err)
+	}
+	lsp.Tree.ResolveReferences()
+
+	// Check if SubComp is in the tree
+	// Root -> App -> SubComp
+	appNode := lsp.Tree.Root.Children["App"]
+	if appNode == nil {
+		t.Fatal("App package not found")
+	}
+
+	subComp := appNode.Children["SubComp"]
+	if subComp == nil {
+		t.Fatal("SubComp not found in tree (recursive scan failed)")
+	}
+
+	mainURI := "file://" + filepath.Join(rootDir, "main.marte")
+
+	// Definition Request
+	params := lsp.DefinitionParams{
+		TextDocument: lsp.TextDocumentIdentifier{URI: mainURI},
+		Position:     lsp.Position{Line: 3, Character: 12},
+	}
+
+	res := lsp.HandleDefinition(params)
+	if res == nil {
+		t.Fatal("Definition not found for SubComp")
+	}
+
+	locs, ok := res.([]lsp.Location)
+	if !ok || len(locs) == 0 {
+		t.Fatal("Expected location list")
+	}
+
+	expectedFile := filepath.Join(subDir, "sub.marte")
+	if locs[0].URI != "file://"+expectedFile {
+		t.Errorf("Expected definition in %s, got %s", expectedFile, locs[0].URI)
+	}
+}

test/recursive_indexing_test.go

@@ -0,0 +1,54 @@
+package integration
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+)
+
+func TestRecursiveIndexing(t *testing.T) {
+	// Setup: root/level1/level2/deep.marte
+	rootDir, _ := os.MkdirTemp("", "rec_index")
+	defer os.RemoveAll(rootDir)
+
+	l1 := filepath.Join(rootDir, "level1")
+	l2 := filepath.Join(l1, "level2")
+	if err := os.MkdirAll(l2, 0755); err != nil {
+		t.Fatal(err)
+	}
+
+	content := "#package Deep\n+DeepObj = { Class = A }"
+	if err := os.WriteFile(filepath.Join(l2, "deep.marte"), []byte(content), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	// Also add a file in root to ensure mixed levels work
+	os.WriteFile(filepath.Join(rootDir, "root.marte"), []byte("#package Root\n+RootObj = { Class = A }"), 0644)
+
+	// Scan
+	tree := index.NewProjectTree()
+	err := tree.ScanDirectory(rootDir)
+	if err != nil {
+		t.Fatalf("Scan failed: %v", err)
+	}
+
+	// Verify Deep
+	deepPkg := tree.Root.Children["Deep"]
+	if deepPkg == nil {
+		t.Fatal("Package Deep not found")
+	}
+	if deepPkg.Children["DeepObj"] == nil {
+		t.Fatal("DeepObj not found in Deep package")
+	}
+
+	// Verify Root
+	rootPkg := tree.Root.Children["Root"]
+	if rootPkg == nil {
+		t.Fatal("Package Root not found")
+	}
+	if rootPkg.Children["RootObj"] == nil {
+		t.Fatal("RootObj not found in Root package")
+	}
+}