Refactored, added comprehensive testing.

input/role.go

@@ -0,0 +1,26 @@
+package input
+
+import "git.wisehodl.dev/jay/aicli/config"
+
+// DetermineRole decides how stdin content participates in the query based on
+// flags and stdin presence. Per spec §7 rules.
+func DetermineRole(cfg config.ConfigData, hasStdin bool) StdinRole {
+	if !hasStdin {
+		return StdinAsPrompt // unused, but set for consistency
+	}
+
+	// Explicit -F flag forces stdin as file
+	if cfg.StdinAsFile {
+		return StdinAsFile
+	}
+
+	// Any explicit prompt flag (-p or -pf) makes stdin prefixed content
+	hasExplicitPrompt := len(cfg.PromptFlags) > 0 || len(cfg.PromptPaths) > 0
+
+	if hasExplicitPrompt {
+		return StdinAsPrefixedContent
+	}
+
+	// Default: stdin replaces any default prompt
+	return StdinAsPrompt
+}