Refactored, added comprehensive testing.

input/types.go

@@ -0,0 +1,27 @@
+package input
+
+// StdinRole determines how stdin content participates in the query
+type StdinRole int
+
+const (
+	// StdinAsPrompt: stdin becomes the entire prompt (replaces other prompts)
+	StdinAsPrompt StdinRole = iota
+
+	// StdinAsPrefixedContent: stdin appends after explicit prompts
+	StdinAsPrefixedContent
+
+	// StdinAsFile: stdin becomes first file in files array
+	StdinAsFile
+)
+
+// FileData represents a single input file
+type FileData struct {
+	Path    string
+	Content string
+}
+
+// InputData holds all resolved input streams after aggregation
+type InputData struct {
+	Prompts []string
+	Files   []FileData
+}