fix: require JSX return or hook usage for component detection (audit #1)

PascalCase functions in .tsx files were unconditionally indexed as
components. Now maybeAddComponent checks for JSX elements/fragments in
the function body or hook calls before registering — eliminates false
positives like FormatCurrency(), ValidateEmail(), etc.

Added negative test cases for the heuristic; updated the existing
positive test to use actual JSX return.

Author: SutuSebastian

src/parser.test.ts

@@ -35,9 +35,46 @@ describe("extractFileData", () => {
     });
 
     it("treats .tsx as JSX for PascalCase function components", () => {
-      const src = `export function Button() { return null; }\n`;
+      const src = `export function Button() { return <button>click</button>; }\n`;
       const d = extractFileData("/proj/x.tsx", src, "x.tsx");
       expect(d.components.some((c) => c.name === "Button")).toBe(true);
     });
   });
+
+  describe("component detection heuristic", () => {
+    it("detects components that return JSX", () => {
+      const src = `export function Card() { return <div>card</div>; }\n`;
+      const d = extractFileData("/proj/x.tsx", src, "x.tsx");
+      expect(d.components.some((c) => c.name === "Card")).toBe(true);
+    });
+
+    it("detects arrow components that return JSX", () => {
+      const src = `export const Card = () => <div>card</div>;\n`;
+      const d = extractFileData("/proj/x.tsx", src, "x.tsx");
+      expect(d.components.some((c) => c.name === "Card")).toBe(true);
+    });
+
+    it("detects components that use hooks", () => {
+      const src = `export function Timer() { useEffect(() => {}); return null; }\n`;
+      const d = extractFileData("/proj/x.tsx", src, "x.tsx");
+      expect(d.components.some((c) => c.name === "Timer")).toBe(true);
+    });
+
+    it("rejects PascalCase functions without JSX or hooks", () => {
+      const src = [
+        `export function FormatCurrency(n: number): string { return "$"+n; }`,
+        `export function ValidateEmail(e: string): boolean { return e.includes("@"); }`,
+      ].join("\n");
+      const d = extractFileData("/proj/x.tsx", src, "x.tsx");
+      expect(d.components).toHaveLength(0);
+    });
+
+    it("rejects PascalCase functions that return null without hooks", () => {
+      const src = `export function EmptyPlaceholder() { return null; }\n`;
+      const d = extractFileData("/proj/x.tsx", src, "x.tsx");
+      expect(d.components.some((c) => c.name === "EmptyPlaceholder")).toBe(
+        false,
+      );
+    });
+  });
 });

src/parser.ts

@@ -103,6 +103,7 @@ export function extractFileData(
   }
 
   const hookCalls = new Map<string, Set<string>>(); // function scope name -> hook names
+  const jsxScopes = new Set<string>(); // function scopes that contain JSX
   let currentFunctionScope: string | null = null;
 
   const visitor = new Visitor({
@@ -255,6 +256,13 @@ export function extractFileData(
         hookCalls.get(currentFunctionScope)?.add(callee.name);
       }
     },
+
+    JSXElement() {
+      if (currentFunctionScope) jsxScopes.add(currentFunctionScope);
+    },
+    JSXFragment() {
+      if (currentFunctionScope) jsxScopes.add(currentFunctionScope);
+    },
   });
 
   visitor.visit(result.program);
@@ -264,6 +272,8 @@ export function extractFileData(
   function maybeAddComponent(name: string, node: any, _isArrow: boolean) {
     if (!isTsx || !/^[A-Z]/.test(name)) return;
     const hooks = hookCalls.get(name);
+    const hasJsx = jsxScopes.has(name);
+    if (!hasJsx && !(hooks && hooks.size > 0)) return;
     const isDefault = defaultExportedNames.has(name);
 
     let propsType: string | null = null;