Identify pipeline entries in reports and diagnostics

internal/framework/contracts/contracts.go

@@ -70,6 +70,8 @@ func SectionMetadataFromSection(section chunking.Section) SectionMetadata {
 
 // ExecutionContext carries shared execution state for proposal generation and validation.
 type ExecutionContext struct {
+	StageIndex *int    `json:"stage_index,omitempty"`
+	StageID    *string `json:"stage_id,omitempty"`
 	// ReportDiagnosticError may be called concurrently; it must not affect processing.
 	ReportDiagnosticError func(error)        `json:"-"`
 	Settings              config.Stage       `json:"-"`