chore: enforce stricter Biome lint/format rules and TypeScript checks

biome.json

@@ -1,5 +1,5 @@
 {
-  "$schema": "https://biomejs.dev/schemas/2.4.2/schema.json",
+  "$schema": "https://biomejs.dev/schemas/2.4.4/schema.json",
   "assist": {
     "actions": {
       "source": {
@@ -10,21 +10,136 @@
   "linter": {
     "enabled": true,
     "rules": {
-      "recommended": true
+      "recommended": true,
+      "nursery": {
+        "recommended": true,
+        "noShadow": "error",
+        "useExplicitType": "warn",
+        "noEqualsToNull": "error",
+        "noReturnAssign": "error",
+        "useArraySortCompare": "error",
+        "useFind": "warn",
+        "useSpread": "warn"
+      },
+      "correctness": {
+        "recommended": true,
+        "noUnusedImports": "error",
+        "noUnusedVariables": "error",
+        "noUnusedPrivateClassMembers": "error",
+        "noUndeclaredVariables": "error",
+        "noUnreachable": "error",
+        "noInvalidUseBeforeDeclaration": "error"
+      },
+      "style": {
+        "recommended": true,
+        "noDefaultExport": "off",
+        "noParameterAssign": "error",
+        "useBlockStatements": "error",
+        "useCollapsedElseIf": "warn",
+        "useConsistentBuiltinInstantiation": "error",
+        "useDefaultParameterLast": "error",
+        "useExplicitLengthCheck": "warn",
+        "useForOf": "warn",
+        "useFragmentSyntax": "warn",
+        "useImportType": "error",
+        "useShorthandAssign": "warn",
+        "useShorthandFunctionType": "warn",
+        "useThrowNewError": "error",
+        "useThrowOnlyError": "error",
+        "noCommonJs": "error",
+        "noExportedImports": "off",
+        "useNamingConvention": {
+          "level": "warn",
+          "options": {
+            "conventions": [
+              {
+                "selector": { "kind": "variable" },
+                "formats": ["camelCase", "CONSTANT_CASE", "PascalCase"]
+              },
+              {
+                "selector": { "kind": "function" },
+                "formats": ["camelCase", "PascalCase"]
+              },
+              {
+                "selector": { "kind": "typeLike" },
+                "formats": ["PascalCase"]
+              },
+              {
+                "selector": { "kind": "enumMember" },
+                "formats": ["CONSTANT_CASE", "PascalCase"]
+              }
+            ]
+          }
+        },
+        "useFilenamingConvention": {
+          "level": "warn",
+          "options": {
+            "requireAscii": true,
+            "filenameCases": ["PascalCase", "camelCase"]
+          }
+        }
+      },
+      "suspicious": {
+        "recommended": true,
+        "noConsole": "warn",
+        "noEmptyBlockStatements": "error",
+        "noExplicitAny": "warn",
+        "useAwait": "error",
+        "useErrorMessage": "error",
+        "useGuardForIn": "error",
+        "useIsArray": "error",
+        "noIrregularWhitespace": "off"
+      },
+      "complexity": {
+        "recommended": true,
+        "noExcessiveCognitiveComplexity": {
+          "level": "warn",
+          "options": {
+            "maxAllowedComplexity": 25
+          }
+        },
+        "noForEach": "warn",
+        "noStaticOnlyClass": "error",
+        "noUselessStringConcat": "error",
+        "noUselessUndefinedInitialization": "error",
+        "noVoid": "error",
+        "useArrowFunction": "warn",
+        "useDateNow": "error",
+        "useFlatMap": "warn",
+        "useSimplifiedLogicExpression": "warn"
+      },
+      "performance": {
+        "recommended": true,
+        "noAccumulatingSpread": "warn",
+        "noBarrelFile": "warn",
+        "noDelete": "warn",
+        "noReExportAll": "warn"
+      },
+      "a11y": {
+        "recommended": true
+      },
+      "security": {
+        "recommended": true,
+        "noGlobalEval": "error"
+      }
     }
   },
   "formatter": {
     "enabled": true,
     "indentStyle": "space",
-    "indentWidth": 2
+    "indentWidth": 2,
+    "lineWidth": 120
   },
   "files": {
     "includes": ["**/*.ts", "**/*.js", "**/*.json", "**/*.html", "!dist"]
   },
   "javascript": {
     "formatter": {
       "quoteStyle": "double",
-      "semicolons": "always"
+      "semicolons": "always",
+      "trailingCommas": "all",
+      "arrowParentheses": "always",
+      "bracketSameLine": false
     }
   }
 }

scripts/bouncingBallToSVG.ts

@@ -29,10 +29,7 @@ const FLOOR_WIDTH = 0.8; // stroke-width
  *  T_n ∝ sqrt(h_n).  We normalise so the total "time" = 1.
  */
 function buildBounces(): Array<{ tStart: number; tEnd: number; h: number }> {
-  const heights = Array.from(
-    { length: NUM_BOUNCES },
-    (_, n) => INITIAL_HEIGHT * RESTITUTION ** n,
-  );
+  const heights = Array.from({ length: NUM_BOUNCES }, (_, n) => INITIAL_HEIGHT * RESTITUTION ** n);
 
   // flight time ∝ sqrt(h)
   const durations = heights.map((h) => Math.sqrt(h));
@@ -59,9 +56,7 @@ function computeSnapshots(): Point[] {
 
   // x positions of bounce endpoints (floor contacts) spaced proportionally
   // to flight time (= proportional to normalised duration)
-  const xContacts: number[] = bounces.map(
-    (b) => X_START + b.tStart * (X_END - X_START),
-  );
+  const xContacts: number[] = bounces.map((b) => X_START + b.tStart * (X_END - X_START));
   xContacts.push(X_END); // final landing
 
   for (let i = 0; i < TOTAL_SNAPSHOTS; i++) {
@@ -70,7 +65,9 @@ function computeSnapshots(): Point[] {
 
     // find which bounce this snapshot falls in
     const bounce = bounces.find((b) => tGlobal >= b.tStart && tGlobal < b.tEnd);
-    if (!bounce) continue; // shouldn't happen
+    if (!bounce) {
+      continue; // shouldn't happen
+    }
 
     const bounceIdx = bounces.indexOf(bounce);
     // local time within this bounce, in [0, 1]
@@ -93,13 +90,9 @@ function computeSnapshots(): Point[] {
   return points;
 }
 
-function buildSVG(points: Point[]): string {
-  const circles = points
-    .map(
-      (p) =>
-        `  <circle cx="${p.x}" cy="${p.y}" r="${BALL_RADIUS}" ` +
-        `fill="${BALL_COLOR}" opacity="${BALL_OPACITY}"/>`,
-    )
+function buildSvg(snapshots: Point[]): string {
+  const circles = snapshots
+    .map((p) => `  <circle cx="${p.x}" cy="${p.y}" r="${BALL_RADIUS}" fill="${BALL_COLOR}" opacity="${BALL_OPACITY}"/>`)
     .join("\n");
 
   return `<svg xmlns="http://www.w3.org/2000/svg" \
@@ -113,12 +106,9 @@ ${circles}
 }
 
 const points = computeSnapshots();
-const svg = buildSVG(points);
+const svg = buildSvg(points);
 
 // Write to public/icons/icon.svg (source for PNG icon generation)
 const outputPath = "public/icons/icon.svg";
 fs.mkdirSync("public/icons", { recursive: true });
 fs.writeFileSync(outputPath, svg, "utf8");
-console.log(
-  `✓ Generated ${outputPath} with ${points.length} bouncing ball snapshots`,
-);

scripts/generate-icons.ts

@@ -4,8 +4,8 @@ import { fileURLToPath } from "node:url";
 import pngToIco from "png-to-ico";
 import sharp from "sharp";
 
-const __dirname = dirname(fileURLToPath(import.meta.url));
-const root = resolve(__dirname, "..");
+const Dirname = dirname(fileURLToPath(import.meta.url));
+const root = resolve(Dirname, "..");
 
 const svgBuffer = readFileSync(resolve(root, "public/icons/icon.svg"));
 
@@ -19,7 +19,6 @@ const pngIcons = [
 for (const { name, size } of pngIcons) {
   const dest = resolve(root, "public", name);
   await sharp(svgBuffer).resize(size, size).png().toFile(dest);
-  console.log(`Generated ${name} (${size}x${size})`);
 }
 
 // Generate multi-size favicon.ico (16, 32, 48, 64)
@@ -34,4 +33,3 @@ for (const size of faviconSizes) {
 const icoBuffer = await pngToIco(faviconPngs);
 const faviconDest = resolve(root, "public", "favicon.ico");
 writeFileSync(faviconDest, icoBuffer);
-console.log(`Generated favicon.ico (16x16, 32x32, 48x48, 64x64)`);