Spec for the swift3-style ?modal=<path> pattern: same route renders full page
or layoutless fragment based on an HX-Modal header, ~50-line JS module owns
URL+history, HTMX owns fetch+swap, native <dialog> owns show/hide. Pilot
migrates the file editor's open/render flow only — save flow stays AJAX.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
