Refactor page filename logic (#7983)

* fix(#7561): refactor astro page filename logic

* chore: add changeset

3 files changed, 67 insertions, 16 deletions

diff --git a/.changeset/early-planets-knock.md b/.changeset/early-planets-knock.md
new file mode 100644
index 000000000..378e2f4b2
--- /dev/null
+++ b/.changeset/early-planets-knock.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix filename generation for `.astro` pages
diff --git a/packages/astro/src/core/build/static-build.ts b/packages/astro/src/core/build/static-build.ts
index 8e3cf8fa8..95027fd5b 100644
--- a/packages/astro/src/core/build/static-build.ts
+++ b/packages/astro/src/core/build/static-build.ts
@@ -445,22 +445,10 @@ export function makeAstroPageEntryPointFileName(
 	facadeModuleId: string,
 	routes: RouteData[]
 ) {
-	const pageModuleId = facadeModuleId
-		.replace(prefix, '')
-		.replace(ASTRO_PAGE_EXTENSION_POST_PATTERN, '.');
-	let route = routes.find((routeData) => {
-		return routeData.route === pageModuleId;
-	});
-	let name = pageModuleId;
-	if (route) {
-		name = route.route;
-	}
-	if (name.endsWith('/')) name += 'index';
-	const fileName = `${name.replaceAll('[', '_').replaceAll(']', '_').replaceAll('...', '---')}.mjs`;
-	if (name.startsWith('..')) {
-		return `pages${fileName}`;
-	}
-	return fileName;
+	const pageModuleId = facadeModuleId.replace(prefix, '').replace(ASTRO_PAGE_EXTENSION_POST_PATTERN, '.');
+	const route = routes.find((routeData) => routeData.component === pageModuleId);
+	const name = route?.route ?? pageModuleId;
+	return `pages${name.replace(/\/$/, '/index').replaceAll(/[\[\]]/g, '_').replaceAll('...', '---')}.astro.mjs`;
 }
 
 /**
diff --git a/packages/astro/test/units/build/static-build.test.js b/packages/astro/test/units/build/static-build.test.js
new file mode 100644
index 000000000..632b1c429
--- /dev/null
+++ b/packages/astro/test/units/build/static-build.test.js
@@ -0,0 +1,58 @@
+import { expect } from 'chai';
+import { makeAstroPageEntryPointFileName } from '../../../dist/core/build/static-build.js';
+
+describe('astro/src/core/build', () => {
+    describe('makeAstroPageEntryPointFileName', () => {
+        const routes = [
+            {
+                route: '/',
+                component: 'src/pages/index.astro',
+                pathname: '/',
+            },
+            {
+                route: '/injected',
+                component: '../node_modules/my-dep/injected.astro',
+                pathname: '/injected',
+            },
+            {
+                route: '/injected-workspace',
+                component: '../../packages/demo/[...all].astro',
+                pathname: undefined,
+            },
+            {
+                route: '/blog/[year]/[...slug]',
+                component: 'src/pages/blog/[year]/[...slug].astro',
+                pathname: undefined,
+            },
+        ]
+
+        it('handles local pages', async () => {
+            const input = '@astro-page:src/pages/index@_@astro';
+            const output = 'pages/index.astro.mjs';
+            const result = makeAstroPageEntryPointFileName('@astro-page:', input, routes);
+            expect(result).to.equal(output)
+        });
+
+        it('handles dynamic pages', async () => {
+            const input = '@astro-page:src/pages/blog/[year]/[...slug]@_@astro';
+            const output = 'pages/blog/_year_/_---slug_.astro.mjs';
+            const result = makeAstroPageEntryPointFileName('@astro-page:', input, routes);
+            expect(result).to.equal(output)
+        });
+
+        it('handles node_modules pages', async () => {
+            const input = '@astro-page:../node_modules/my-dep/injected@_@astro';
+            const output = 'pages/injected.astro.mjs';
+            const result = makeAstroPageEntryPointFileName('@astro-page:', input, routes);
+            expect(result).to.equal(output)
+        });
+
+        // Fix #7561
+        it('handles local workspace pages', async () => {
+            const input = '@astro-page:../../packages/demo/[...all]@_@astro';
+            const output = 'pages/injected-workspace.astro.mjs';
+            const result = makeAstroPageEntryPointFileName('@astro-page:', input, routes);
+            expect(result).to.equal(output)
+        });
+    });
+});