refactor(canvas): tighten ^GS code per second review

Five small follow-ups from the post-feature review:

- `GS_VECTOR_CODES` set + `GsVectorCode` type replace the magic
  `'A' | 'B' | 'C'` cast at the canvas lookup. Adding D/E to the
  vector set later is a one-line change rather than a silently-
  broken cast.
- `DEFAULT_GS_SYMBOL_META` switches from positional `GS_SYMBOLS[1]`
  to a `find()` on the canonical code so reordering the symbol
  table doesn't break the fallback.
- Defensive `rel[p.rotation] ?? rel.N` in the sceneFunc handles
  malformed JSON imports with an unexpected rotation string
  without crashing the entire Konva layer.
- `gsSymbolPaths.ts` (and the regen-from-cache template) now reuse
  `ZplRotation` from `registry/rotation.ts` instead of declaring a
  local duplicate `GsRotation`, and ship an AUTO-GENERATED header
  so the next maintainer doesn't hand-edit them.
- Stale comment ("falls back to the © path") corrected to match
  the actual null-fallback that routes to the placeholder branch.

Author: u8array

src/components/Canvas/KonvaObject.tsx

@@ -16,7 +16,7 @@ import { ZPL_FONT_HEIGHT_TO_CSS_RATIO } from "./textPositionTransforms";
 import { getTextRenderMetrics } from "./textRenderMetrics";
 import { selectionHandlers, type KonvaObjectProps } from "./konvaObjectProps";
 import { DEFAULT_GS_SYMBOL_META, GS_SYMBOLS } from "../../registry/symbol";
-import { GS_SYMBOL_PATHS } from "../../registry/gsSymbolPaths";
+import { GS_SYMBOL_PATHS, GS_VECTOR_CODES, type GsVectorCode } from "../../registry/gsSymbolPaths";
 
 type Props = KonvaObjectProps;
 
@@ -391,8 +391,11 @@ function KonvaObjectInner({
     // to Zebra firmware). D/E are trademarked UL/CSA logos we can't
     // ship — render a clearly-placeholder dashed gray box with the
     // letters so the user knows the printer will substitute the real
-    // logo. Falls back to the © path if an unknown code slips through.
-    const vectorPath = GS_SYMBOL_PATHS[p.symbol as 'A' | 'B' | 'C'] ?? null;
+    // logo. Unknown codes (D/E or malformed import) take the same
+    // placeholder branch via the null path here.
+    const vectorPath = GS_VECTOR_CODES.has(p.symbol)
+      ? GS_SYMBOL_PATHS[p.symbol as GsVectorCode]
+      : null;
     // The field bbox itself doesn't rotate — Zebra keeps the ^FO
     // anchor and (w, h) extent fixed and rotates only the glyph
     // inside. Skip the outer rotatedGroupTransform; sceneFunc bakes
@@ -427,7 +430,12 @@ function KonvaObjectInner({
             // inside the declared bbox, measured directly from
             // Labelary so Zebra's per-rotation anchor offsets match
             // pixel-for-pixel.
-            const rel = vectorPath.rel[p.rotation];
+            // Defensive ?? rel.N for the malformed-import case where
+            // a JSON-restored object slips a non-N/R/I/B rotation
+            // string past the type system; falling back to the
+            // upright entry keeps the canvas from crashing on bad
+            // data instead of throwing inside sceneFunc.
+            const rel = vectorPath.rel[p.rotation] ?? vectorPath.rel.N;
             const glyphW = vectorPath.bbox.maxX - vectorPath.bbox.minX;
             const glyphH = vectorPath.bbox.maxY - vectorPath.bbox.minY;
             const renderW = w * rel.w;

src/registry/gsSymbolPaths.ts

@@ -1,4 +1,8 @@
 /**
+ * AUTO-GENERATED by scripts/regen_gs_from_cache.local.ts.
+ * Do not edit by hand — re-run the generator after refreshing the
+ * cached Labelary PNGs under tests/fixtures/labelary_images/_gs_*.
+ *
  * Vector paths for the ®/©/™ glyphs Zebra firmware renders via ^GS.
  * Generated from cached Labelary renders at 8 dpmm. Each code carries
  * the upright (N) vector plus per-rotation glyph rect within the
@@ -10,7 +14,7 @@
  * canvas shows a clearly-labelled placeholder instead.
  */
 
-export type GsRotation = 'N' | 'R' | 'I' | 'B';
+import type { ZplRotation } from './rotation';
 
 export interface GsSymbolPath {
   readonly d: string;
@@ -19,12 +23,19 @@ export interface GsSymbolPath {
    *  Canvas picks the entry matching the field's rotation and
    *  draws the path at (userW * rel.x, userH * rel.y) sized
    *  (userW * rel.w, userH * rel.h). */
-  readonly rel: Readonly<Record<GsRotation, {
+  readonly rel: Readonly<Record<ZplRotation, {
     readonly x: number; readonly y: number; readonly w: number; readonly h: number;
   }>>;
 }
 
-export const GS_SYMBOL_PATHS: Readonly<Record<'A' | 'B' | 'C', GsSymbolPath>> = {
+/** Codes for which we ship a vector path. D/E intentionally absent
+ *  (trademarked UL/CSA logos rendered as a clearly-placeholder dashed
+ *  box). Renderers narrow via `GS_VECTOR_CODES.has(code)` instead of
+ *  casting through the literal union. */
+export type GsVectorCode = 'A' | 'B' | 'C';
+export const GS_VECTOR_CODES: ReadonlySet<string> = new Set<GsVectorCode>(['A', 'B', 'C']);
+
+export const GS_SYMBOL_PATHS: Readonly<Record<GsVectorCode, GsSymbolPath>> = {
   A: {
     bbox: { minX: 49.602, minY: 50.673, maxX: 169.333, maxY: 170 },
     rel: {

src/registry/symbol.tsx

@@ -29,8 +29,10 @@ export type SymbolCode = (typeof GS_SYMBOLS)[number]['code'];
 export const DEFAULT_GS_SYMBOL: SymbolCode = 'B';
 /** Resolved GS_SYMBOLS entry for the DEFAULT_GS_SYMBOL code. Renderers
  *  use this as a typed fallback when `find` returns undefined, so they
- *  can avoid non-null assertions on the lookup result. */
-export const DEFAULT_GS_SYMBOL_META = GS_SYMBOLS[1]; // 'B' = ©
+ *  can avoid non-null assertions on the lookup result. Looked up by
+ *  code so reordering GS_SYMBOLS doesn't silently break the fallback. */
+export const DEFAULT_GS_SYMBOL_META =
+  GS_SYMBOLS.find((s) => s.code === DEFAULT_GS_SYMBOL) ?? GS_SYMBOLS[0];
 
 /** Set of recognised ^GS codes — used by the parser to validate the
  *  ^FD payload without re-listing the letters. Single source of truth