fix: prevent root wildcard static routes from overriding mount routes (#1515)

aunak · aunak · commit cb7982b79dcd · 2026-01-19T18:31:35.000+05:30
When using static Response/HTMLBundle on root wildcard routes (e.g., GET /*), Bun's nativeStaticResponse optimization would add them to Bun's static route table, which has highest priority and bypasses Elysia's dynamic router. This caused SPA fallback patterns with mounted APIs to fail: app.mount('/api', backend) .get('/*', staticHtmlResponse) The /api/* routes would return HTML instead of API responses because the /* wildcard in Bun's static table matched everything. Solution: - During listen(), collect mount prefixes by scanning router.history for routes with hooks.config.mount flag - In createStaticRoute(), skip root wildcard paths (/* or /) when mounts exist - This forces root wildcards through the dynamic router where the route specificity fix from #1682 correctly handles priority Production-grade approach: - Minimal performance impact: only scans during .listen() once - Surgical fix: only affects root wildcards when mounts exist - Preserves optimization: specific static routes still go to Bun table - Backwards compatible: doesn't break existing apps without mounts Fixes #1515
diff --git a/src/adapter/bun/index.ts b/src/adapter/bun/index.ts
@@ -226,6 +226,17 @@ export const BunAdapter: ElysiaAdapter = {
 				options = parseInt(options)
 			}
 
+			// Collect mount prefixes to prevent wildcard static routes from overriding them
+			// Mount routes are registered as ALL with config.mount, often with paths like /api/* 
+			const mountPrefixes = new Set<string>()
+			for (const route of app.router.history) {
+				if (route.hooks?.config?.mount && route.path.includes('*')) {
+					// Extract prefix from paths like /api/* or /v1/*
+					const prefix = route.path.slice(0, route.path.lastIndexOf('/*'))
+					if (prefix) mountPrefixes.add(prefix)
+				}
+			}
+
 			const createStaticRoute = <
 				WithAsync extends boolean | undefined = false
 			>(
@@ -254,6 +265,17 @@ export const BunAdapter: ElysiaAdapter = {
 				for (let [path, route] of Object.entries(iterator)) {
 					path = encodeURI(path)
 
+					// Skip wildcard static routes that would override mount prefixes
+					// e.g., skip GET /* if we have mounts like /api/* or /v1/*
+					if (path.endsWith('/*') && mountPrefixes.size > 0) {
+						const wildcardPrefix = path.slice(0, -2) // Remove /*
+						// If this is a root wildcard /* and we have any mounts, skip it
+						// to let the dynamic router handle route priority correctly
+						if (wildcardPrefix === '' || wildcardPrefix === '/') {
+							continue
+						}
+					}
+
 					if (supportPerMethodInlineHandler) {
 						if (!route) continue
 
diff --git a/test/core/spa-fallback.test.ts b/test/core/spa-fallback.test.ts
@@ -0,0 +1,187 @@
+import { describe, it, expect } from 'bun:test'
+import { Elysia } from '../../src'
+
+describe('SPA Fallback Routing - Issue #1515', () => {
+	it('handles mount routes with root wildcard static response', async () => {
+		const backend = new Elysia().get('/users', () => ({
+			users: ['alice', 'bob']
+		}))
+
+		const staticHtml = new Response('<html><body>SPA</body></html>', {
+			headers: { 'content-type': 'text/html' }
+		})
+
+		const app = new Elysia()
+			.mount('/api', backend)
+			.get('/*', staticHtml)
+			.listen(0)
+
+		const apiResponse = await app
+			.handle(new Request(`http://localhost/api/users`))
+			.then((r) => r.json())
+
+		const spaResponse = await app
+			.handle(new Request(`http://localhost/other`))
+			.then((r) => r.text())
+
+		expect(apiResponse).toEqual({ users: ['alice', 'bob'] })
+		expect(spaResponse).toContain('SPA')
+
+		await app.server!.stop()
+	})
+
+	it('handles multiple mounts with root wildcard', async () => {
+		const backend = new Elysia().get('/users', () => ({ users: ['test'] }))
+
+		const staticHtml = new Response('<html>SPA</html>', {
+			headers: { 'content-type': 'text/html' }
+		})
+
+		const app = new Elysia()
+			.mount('/api', backend)
+			.mount('/v2', backend)
+			.get('/*', staticHtml)
+			.listen(0)
+
+		const api1 = await app
+			.handle(new Request('http://localhost/api/users'))
+			.then((r) => r.json())
+
+		const api2 = await app
+			.handle(new Request('http://localhost/v2/users'))
+			.then((r) => r.json())
+
+		const spa = await app
+			.handle(new Request('http://localhost/other'))
+			.then((r) => r.text())
+
+		expect(api1).toEqual({ users: ['test'] })
+		expect(api2).toEqual({ users: ['test'] })
+		expect(spa).toContain('SPA')
+
+		await app.server!.stop()
+	})
+
+	it('respects order - wildcard registered before mount', async () => {
+		const backend = new Elysia().get('/users', () => ({ data: 'api' }))
+
+		const staticHtml = new Response('<html>SPA</html>', {
+			headers: { 'content-type': 'text/html' }
+		})
+
+		const app = new Elysia()
+			.get('/*', staticHtml)
+			.mount('/api', backend)
+			.listen(0)
+
+		const api = await app
+			.handle(new Request('http://localhost/api/users'))
+			.then((r) => r.json())
+
+		const spa = await app
+			.handle(new Request('http://localhost/other'))
+			.then((r) => r.text())
+
+		expect(api).toEqual({ data: 'api' })
+		expect(spa).toContain('SPA')
+
+		await app.server!.stop()
+	})
+
+	it('handles POST requests to mounted routes', async () => {
+		const backend = new Elysia().post('/auth', () => ({ token: 'xyz' }))
+
+		const staticHtml = new Response('<html>SPA</html>', {
+			headers: { 'content-type': 'text/html' }
+		})
+
+		const app = new Elysia()
+			.mount('/api', backend)
+			.get('/*', staticHtml)
+			.listen(0)
+
+		const response = await app
+			.handle(new Request('http://localhost/api/auth', { method: 'POST' }))
+			.then((r) => r.json())
+
+		expect(response).toEqual({ token: 'xyz' })
+
+		await app.server!.stop()
+	})
+
+	it('allows specific wildcard paths with mounts', async () => {
+		const backend = new Elysia().get('/users', () => ({ data: 'api' }))
+
+		const publicHtml = new Response('<html>Public</html>', {
+			headers: { 'content-type': 'text/html' }
+		})
+
+		const app = new Elysia()
+			.mount('/api', backend)
+			.get('/public/*', publicHtml)
+			.listen(0)
+
+		const api = await app
+			.handle(new Request('http://localhost/api/users'))
+			.then((r) => r.json())
+
+		const publicAsset = await app
+			.handle(new Request('http://localhost/public/asset.js'))
+			.then((r) => r.text())
+
+		expect(api).toEqual({ data: 'api' })
+		expect(publicAsset).toContain('Public')
+
+		await app.server!.stop()
+	})
+
+	it('preserves normal wildcard behavior without mounts', async () => {
+		const staticHtml = new Response('<html>SPA</html>', {
+			headers: { 'content-type': 'text/html' }
+		})
+
+		const app = new Elysia()
+			.get('/api/users', () => ({ users: ['alice'] }))
+			.get('/*', staticHtml)
+			.listen(0)
+
+		const api = await app
+			.handle(new Request('http://localhost/api/users'))
+			.then((r) => r.json())
+
+		const spa = await app
+			.handle(new Request('http://localhost/other'))
+			.then((r) => r.text())
+
+		expect(api).toEqual({ users: ['alice'] })
+		expect(spa).toContain('SPA')
+
+		await app.server!.stop()
+	})
+
+	it('handles nested mount paths correctly', async () => {
+		const backend = new Elysia().get('/status', () => ({ status: 'ok' }))
+
+		const staticHtml = new Response('<html>SPA</html>', {
+			headers: { 'content-type': 'text/html' }
+		})
+
+		const app = new Elysia()
+			.mount('/api/v1', backend)
+			.get('/*', staticHtml)
+			.listen(0)
+
+		const api = await app
+			.handle(new Request('http://localhost/api/v1/status'))
+			.then((r) => r.json())
+
+		const spa = await app
+			.handle(new Request('http://localhost/other'))
+			.then((r) => r.text())
+
+		expect(api).toEqual({ status: 'ok' })
+		expect(spa).toContain('SPA')
+
+		await app.server!.stop()
+	})
+})
