refactor(cli): extract platform validation and error reporting functions

Extract platform detection and error reporting logic into reusable functions
to improve testability and reduce code duplication in the binary launcher.
Adds comprehensive test coverage for platform validation and error messages.

cli/src/bin/hapiBin.test.ts

@@ -5,7 +5,14 @@ import { describe, expect, it } from 'vitest';
 
 const require = createRequire(import.meta.url);
 const binModulePath = path.resolve(process.cwd(), 'bin/hapi.cjs');
-const { formatCommand, normalizeExecError, reportExecutionFailure } = require(binModulePath);
+const {
+    formatCommand,
+    isSupportedPlatform,
+    normalizeExecError,
+    reportExecutionFailure,
+    reportMissingPlatformPackage,
+    reportUnsupportedPlatform,
+} = require(binModulePath);
 
 describe('hapi binary launcher error reporting', () => {
     it('formats command with shell-safe JSON quoting', () => {
@@ -61,4 +68,33 @@ describe('hapi binary launcher error reporting', () => {
         expect(result).toEqual({ status: null, signal: null });
         expect(lines).toEqual(['Failed to execute: "/tmp/hapi"']);
     });
+
+    it('distinguishes supported and unsupported platforms', () => {
+        expect(isSupportedPlatform('linux', 'x64')).toBe(true);
+        expect(isSupportedPlatform('linux', 'ppc64')).toBe(false);
+    });
+
+    it('reports unsupported platform with supported list', () => {
+        const lines: string[] = [];
+        reportUnsupportedPlatform('linux', 'ppc64', (line: string) => {
+            lines.push(line);
+        });
+
+        expect(lines).toContain('Unsupported platform: linux-ppc64');
+        expect(lines).toContain('Supported platforms:');
+        expect(lines).toContain('  - linux-x64');
+    });
+
+    it('reports missing platform package with installation guidance', () => {
+        const lines: string[] = [];
+        reportMissingPlatformPackage('linux', 'x64', (line: string) => {
+            lines.push(line);
+        });
+
+        expect(lines).toContain('Missing platform package: @twsxtd/hapi-linux-x64');
+        expect(lines).toContain('Try reinstalling with the official npm registry:');
+        expect(lines).toContain('  npm install -g @twsxtd/hapi --registry=https://registry.npmjs.org');
+        expect(lines).toContain('Or download the binary manually from:');
+        expect(lines).toContain('  https://github.com/tiann/hapi/releases');
+    });
 });