chore: import upstream snapshot with attribution

cmd/gortex/structured_arg.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+// readStructuredArg resolves a JSON argument from, in precedence order:
+//
+//  1. the inline value, when non-empty and not "-"
+//  2. the file path, when non-empty
+//  3. stdin, when the inline value is exactly "-"
+//
+// It is the shared lowering primitive for the edit verb's JSON-shaped
+// parameters (verify_change's changes, preview_edit's workspace_edit,
+// simulate_chain's steps, batch_edit's edits, change_contract's ranges).
+// The returned value is the verbatim JSON bytes (validated as syntactically
+// well-formed JSON); the caller decides whether to forward it as a string or
+// a parsed value. An empty result (no source provided) returns (nil, nil) so
+// the caller can decide whether the argument is required.
+//
+// stdinReader is injected so tests can drive the "-" path without touching
+// the process's real stdin; nil falls back to os.Stdin.
+func readStructuredArg(inline, file string, stdinReader io.Reader) (json.RawMessage, error) {
+	var (
+		data   []byte
+		source string
+	)
+	switch {
+	case inline == "-":
+		r := stdinReader
+		if r == nil {
+			r = os.Stdin
+		}
+		b, err := io.ReadAll(r)
+		if err != nil {
+			return nil, fmt.Errorf("reading JSON from stdin: %w", err)
+		}
+		data, source = b, "stdin"
+	case inline != "":
+		data, source = []byte(inline), "inline JSON"
+	case file != "":
+		b, err := os.ReadFile(file)
+		if err != nil {
+			return nil, fmt.Errorf("reading JSON file %s: %w", file, err)
+		}
+		data, source = b, fmt.Sprintf("file %s", file)
+	default:
+		return nil, nil
+	}
+
+	trimmed := strings.TrimSpace(string(data))
+	if trimmed == "" {
+		return nil, fmt.Errorf("%s is empty", source)
+	}
+	if !json.Valid([]byte(trimmed)) {
+		return nil, fmt.Errorf("%s is not valid JSON", source)
+	}
+	return json.RawMessage(trimmed), nil
+}