diff --git a/src/index.ts b/src/index.ts
index 8a268e9..7729369 100755
--- a/src/index.ts
+++ b/src/index.ts
@@ -18,6 +18,7 @@ import { type Color, colorFromName } from './utils/color'
 import { loadEnvFiles } from './utils/env-file'
 import { LogWriter } from './utils/log-writer'
 import { enableDebugLog } from './utils/logger'
+import { defaultLogDir } from './utils/project-name'
 import { setupShutdownHandlers } from './utils/shutdown'
 
 const HELP = generateHelp()
@@ -235,8 +236,8 @@ async function main() {
 
 	const manager = new ProcessManager(config)
 
-	const logDir = parsed.logDir ?? config.logDir
-	const logWriter = logDir ? LogWriter.createPersistent(logDir) : LogWriter.createTemp()
+	const logDir = parsed.logDir ?? config.logDir ?? defaultLogDir(process.cwd())
+	const logWriter = LogWriter.createPersistent(logDir)
 
 	printWarnings(warnings)
 
diff --git a/src/utils/project-name.test.ts b/src/utils/project-name.test.ts
new file mode 100644
index 0000000..f1ea533
--- /dev/null
+++ b/src/utils/project-name.test.ts
@@ -0,0 +1,65 @@
+import { afterEach, beforeEach, describe, expect, test } from 'bun:test'
+import { mkdirSync, rmSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { defaultLogDir, resolveProjectName } from './project-name'
+
+describe('resolveProjectName', () => {
+	let dir: string
+
+	beforeEach(() => {
+		dir = join(tmpdir(), `numux-test-${Date.now()}-${Math.random().toString(36).slice(2)}`)
+		mkdirSync(dir, { recursive: true })
+	})
+
+	afterEach(() => {
+		rmSync(dir, { recursive: true })
+	})
+
+	test('reads name from package.json', () => {
+		writeFileSync(join(dir, 'package.json'), JSON.stringify({ name: 'my-app' }))
+		expect(resolveProjectName(dir)).toBe('my-app')
+	})
+
+	test('strips npm scope from name', () => {
+		writeFileSync(join(dir, 'package.json'), JSON.stringify({ name: '@org/my-app' }))
+		expect(resolveProjectName(dir)).toBe('my-app')
+	})
+
+	test('falls back to directory basename without package.json', () => {
+		const sub = join(dir, 'my-project')
+		mkdirSync(sub)
+		expect(resolveProjectName(sub)).toBe('my-project')
+	})
+
+	test('falls back to directory basename when name is empty', () => {
+		const sub = join(dir, 'fallback-dir')
+		mkdirSync(sub)
+		writeFileSync(join(sub, 'package.json'), JSON.stringify({ name: '' }))
+		expect(resolveProjectName(sub)).toBe('fallback-dir')
+	})
+
+	test('falls back to directory basename when name is missing', () => {
+		const sub = join(dir, 'no-name')
+		mkdirSync(sub)
+		writeFileSync(join(sub, 'package.json'), JSON.stringify({ version: '1.0.0' }))
+		expect(resolveProjectName(sub)).toBe('no-name')
+	})
+
+	test('falls back to directory basename on invalid JSON', () => {
+		const sub = join(dir, 'bad-json')
+		mkdirSync(sub)
+		writeFileSync(join(sub, 'package.json'), 'not json')
+		expect(resolveProjectName(sub)).toBe('bad-json')
+	})
+})
+
+describe('defaultLogDir', () => {
+	test('returns /tmp/numux/<project-name>', () => {
+		const dir = join(tmpdir(), `numux-test-${Date.now()}`)
+		mkdirSync(dir, { recursive: true })
+		writeFileSync(join(dir, 'package.json'), JSON.stringify({ name: 'cool-app' }))
+		expect(defaultLogDir(dir)).toBe(join(tmpdir(), 'numux', 'cool-app'))
+		rmSync(dir, { recursive: true })
+	})
+})
diff --git a/src/utils/project-name.ts b/src/utils/project-name.ts
new file mode 100644
index 0000000..558ad65
--- /dev/null
+++ b/src/utils/project-name.ts
@@ -0,0 +1,25 @@
+import { existsSync, readFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { basename, join } from 'node:path'
+
+/** Resolve project name from package.json name (scope-stripped) or directory basename. */
+export function resolveProjectName(cwd: string): string {
+	try {
+		const pkgPath = join(cwd, 'package.json')
+		if (existsSync(pkgPath)) {
+			const pkg = JSON.parse(readFileSync(pkgPath, 'utf-8'))
+			if (typeof pkg.name === 'string' && pkg.name.trim()) {
+				// Strip npm scope (e.g. @org/name -> name)
+				return pkg.name.replace(/^@[^/]+\//, '').trim()
+			}
+		}
+	} catch {
+		// Fall through to directory name
+	}
+	return basename(cwd)
+}
+
+/** Default log directory: /tmp/numux/<project-name> */
+export function defaultLogDir(cwd: string): string {
+	return join(tmpdir(), 'numux', resolveProjectName(cwd))
+}