Fix Bun Elysia entry point detection

gdf.js

@@ -836,6 +836,42 @@ export class GDF {
     return this.bun ? 'bunx' : 'npx'
   }
 
+  get bunStartCommand() {
+    const candidates = []
+
+    for (const entry of [this.#pj.module, this.#pj.main]) {
+      if (!entry) continue
+
+      candidates.push(entry)
+      const extension = path.extname(entry)
+      const typescriptEntry = extension
+        ? `${entry.slice(0, -extension.length)}.ts`
+        : `${entry}.ts`
+      if (typescriptEntry !== entry) candidates.push(typescriptEntry)
+    }
+
+    const devScript = this.#pj.scripts?.dev
+    if (devScript) {
+      const commands = new Set(['bun', 'bunx', 'node', 'npx', 'npm', 'pnpm', 'yarn', 'tsx', 'ts-node', 'run', 'exec'])
+      const entries = ShellQuote.parse(devScript)
+        .filter(entry => typeof entry === 'string' && !entry.startsWith('-') && !commands.has(entry))
+        .reverse()
+
+      for (const entry of entries) {
+        candidates.push(entry)
+        const extension = path.extname(entry)
+        const typescriptEntry = extension
+          ? `${entry.slice(0, -extension.length)}.ts`
+          : `${entry}.ts`
+        if (typescriptEntry !== entry) candidates.push(typescriptEntry)
+      }
+    }
+
+    candidates.push('src/index.ts', 'index.ts')
+    const entry = candidates.find(filename => fs.existsSync(path.join(this._appdir, filename)))
+    return ['bun', entry || 'index.ts']
+  }
+
   // command to start the web server
   get startCommand() {
     if (this.options.cmd) return this.options.cmd
@@ -882,6 +918,8 @@ export class GDF {
       return start
     } else if (this.#pj.scripts?.start) {
       return [this.packager, 'run', 'start']
+    } else if (this.bun) {
+      return this.bunStartCommand
     } else if (this.#pj.type === 'module' && this.#pj.module) {
       return [this.packager === 'bun' ? 'bun' : 'node', this.#pj.module]
     } else if (this.#pj.main) {

test/gdf.test.js

@@ -656,6 +656,7 @@ describe('gdf: start command and port', function() {
   it('uses bun for module, main and the default entry point', async function() {
     sandbox().stub('bun', 'echo 1.1.20\n')
     sandbox().write('bun.lockb', '')
+    sandbox().write('app.ts', '')
 
     let gdf = await sandbox().run({ main: 'app.ts' })
     expect(gdf.startCommand).to.deep.equal(['bun', 'app.ts'])
@@ -664,6 +665,41 @@ describe('gdf: start command and port', function() {
     expect(gdf.startCommand).to.deep.equal(['bun', 'index.ts'])
   })
 
+  it('resolves a Bun module entry point to its TypeScript file when type is unspecified', async function() {
+    sandbox().stub('bun', 'echo 1.1.20\n')
+    sandbox().write('bun.lockb', '')
+    sandbox().write('src/index.ts', '')
+
+    const gdf = await sandbox().run({ module: 'src/index.js' })
+    expect(gdf.startCommand).to.deep.equal(['bun', 'src/index.ts'])
+  })
+
+  it('uses the Bun dev entry point without --watch', async function() {
+    sandbox().stub('bun', 'echo 1.1.20\n')
+    sandbox().write('bun.lockb', '')
+    sandbox().write('src/server.ts', '')
+
+    const gdf = await sandbox().run({ scripts: { dev: 'bun --watch src/server.ts' } })
+    expect(gdf.startCommand).to.deep.equal(['bun', 'src/server.ts'])
+  })
+
+  it('runs a Bun start script when one is defined', async function() {
+    sandbox().stub('bun', 'echo 1.1.20\n')
+    sandbox().write('bun.lockb', '')
+
+    const gdf = await sandbox().run({ scripts: { start: 'bun src/server.ts' } })
+    expect(gdf.startCommand).to.deep.equal(['bun', 'run', 'start'])
+  })
+
+  it('uses src/index.ts when a Bun project has no module or dev entry point', async function() {
+    sandbox().stub('bun', 'echo 1.1.20\n')
+    sandbox().write('bun.lockb', '')
+    sandbox().write('src/index.ts', '')
+
+    const gdf = await sandbox().run({})
+    expect(gdf.startCommand).to.deep.equal(['bun', 'src/index.ts'])
+  })
+
   it('starts standalone next.js with server.js', async function() {
     for (const config of ['next.config.js', 'next.config.mjs']) {
       fs.rmSync('next.config.js', { force: true })