feat(layout): renderer renders tile border markers (main red / side green)

1 files changed, 25 insertions, 0 deletions

diff --git a/src/features/layout/logic/marker.ts b/src/features/layout/logic/marker.ts
new file mode 100644
index 0000000..eb1ff84
--- /dev/null
+++ b/src/features/layout/logic/marker.ts
@@ -0,0 +1,25 @@
+/**
+ * Diagnostic tile-border markers (the contract's additive `TileMarker`
+ * presentation field) → the inline outline the renderer draws. Pure
+ * decision logic — the .svelte tile components just apply the returned
+ * style value.
+ *
+ * INLINE STYLES, deliberately: a marker value arrives in TREE DATA at
+ * runtime, and Tailwind only generates classes it sees in source files — a
+ * dynamic class from tree data would silently render nothing. An outline
+ * (not a border) is used so the diagnostic draws WITHOUT changing any
+ * tile's layout/size (4px solid, clearly visible).
+ *
+ * The marker is purely presentational: unknown/absent → no outline
+ * (existing trees render exactly as before), and no other behavior is
+ * attached to it anywhere in the renderer.
+ */
+
+import type { TileMarker } from "@dispatch/layout-contract";
+
+/** The diagnostic outline style for a marker — `undefined` = draw nothing. */
+export function markerOutline(marker: TileMarker | undefined): string | undefined {
+  if (marker === "main") return "4px solid red";
+  if (marker === "side") return "4px solid green";
+  return undefined;
+}