Apply explicit CLI configuration overrides

load.go

@@ -20,7 +20,7 @@ type Definition[T any] struct {
 
 // Options contains the application definition and per-load input selections.
 // Imports enables explicit path and glob imports; Profile selects one fixed profile
-// overlay. Explicit overrides remain unavailable until implemented.
+// overlay; Overrides contains only values explicitly supplied by an application CLI.
 type Options[T any] struct {
 	Definition Definition[T]
 	Imports    bool
@@ -35,7 +35,9 @@ type FilesystemContext struct {
 	Root    string
 }
 
-// Override describes one explicitly supplied application override.
+// Override describes one explicitly supplied application override. Value uses
+// parser-neutral built-in scalars, nil, []any, or map[string]any; Flag is a safe
+// display name and must not contain a raw argument or value.
 type Override struct {
 	Path  Path
 	Value any
@@ -70,6 +72,7 @@ type Result[T any] struct {
 	diagnostics []Diagnostic
 	final       *document.Node
 	resolution  []resolutionSnapshot
+	overlays    []overlayRecord
 	secrets     map[string]bool
 }
 
@@ -180,6 +183,29 @@ func loadWithSecretLookup[T any](source Source, lookup secretLookup, supplied ..
 		}
 		inputDocument = composition.root
 	}
+	if len(options.Overrides) != 0 {
+		if composition == nil {
+			if inputDocument == nil {
+				composition = &composedDocument{root: &document.Node{Kind: document.Mapping}, origins: make(map[string]Origin)}
+			} else {
+				composition, diagnostics = composeDocuments(inputDocument)
+				if len(diagnostics) != 0 {
+					accumulator.add(diagnostics...)
+					return nil, accumulator.loadError()
+				}
+				composition.inputBytes = parsed.bytes
+				composition.inputNodes = countInputNodes(inputDocument)
+			}
+		}
+		composition, accumulator.sources, diagnostics = applyOverrides(
+			composition, accumulator.sources, options.Overrides, options.Definition.Version, defaultImportLimits(),
+		)
+		if len(diagnostics) != 0 {
+			accumulator.add(diagnostics...)
+			return nil, accumulator.loadError()
+		}
+		inputDocument = composition.root
+	}
 
 	defaults := reflect.Zero(reflect.TypeFor[T]())
 	if options.Definition.Defaults != nil {
@@ -226,6 +252,10 @@ func loadWithSecretLookup[T any](source Source, lookup secretLookup, supplied ..
 		}
 	}
 	secrets := classifySecretPaths(schema, options.Definition.Secret, metadata, final)
+	var overlaySnapshots []overlayRecord
+	if composition != nil {
+		overlaySnapshots = cloneOverlayRecords(composition.overlays)
+	}
 	return &Result[T]{
 		Config:      configuration,
 		metadata:    metadata,
@@ -233,6 +263,7 @@ func loadWithSecretLookup[T any](source Source, lookup secretLookup, supplied ..
 		diagnostics: canonicalDiagnostics(accumulator.diagnostics),
 		final:       document.Clone(final),
 		resolution:  cloneResolutionSnapshots(resolutionSnapshots),
+		overlays:    overlaySnapshots,
 		secrets:     secrets,
 	}, nil
 }
@@ -253,9 +284,6 @@ func selectOptions[T any](source Source, supplied []Options[T]) (Options[T], []D
 	if options.Filesystem != nil {
 		diagnostics = append(diagnostics, filesystemOptionDiagnostics(source, options.Filesystem)...)
 	}
-	if len(options.Overrides) != 0 {
-		diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsUnavailable, "configuration overrides are not available in this release boundary"))
-	}
 	if source.kind == sourceNone && options.Imports {
 		diagnostics = append(diagnostics, optionDiagnostic(CodeOptionsInvalid, "NoSource cannot enable imports"))
 	}