fix: attribute redirect-driven content misses to the requested path

The template pattern for a content miss is Astro.redirect("/404"): the
first pass answers 302 — which the 404 logger never saw — and only the
follow-up /404 render logged, as one aggregate "/404" row. The real
missed path was never recorded, and excluding /404 alone would have
removed the only signal those misses had.

Log the miss on the first pass instead, keyed by the requested path,
when a route answers with a redirect whose target is the error page.
Direct hits on /404 stay unlogged — the route answers 404 by design and
carries no path information.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017m3BaSx6e1DQcU77hBLTxU

Author: edrpls

.changeset/404-log-error-page.md

@@ -2,4 +2,4 @@
 "emdash": patch
 ---
 
-Fixes the 404 log counting the site's own /404 error page as a missed path. Every content miss that redirects to /404 was logged twice — once for the real missing path and once for "/404" itself — inflating the 404 summary with a meaningless top entry. Hits on /404 are no longer logged.
+Fixes 404 logging for content misses. Templates answer a missing entry with a redirect to /404, which previously left the real missed path unrecorded — the log only ever accumulated one aggregate "/404" row. Misses are now logged under the path the visitor actually requested, and hits on the /404 error page itself are no longer logged.

packages/core/src/astro/middleware/redirect.ts

@@ -112,10 +112,18 @@ export const onRequest = defineMiddleware(async (context, next) => {
 		// No redirect matched -- proceed and check for 404
 		const response = await next();
 
-		// Log 404s for unmatched paths (fire-and-forget). Skip /404 itself — Astro
-		// serves the site error page there with status 404 on every render, so logging
-		// it would double-count the original miss after templates redirect here.
-		if (response.status === 404 && pathname !== "/404" && pathname !== "/404/") {
+		// Log misses (fire-and-forget) under the path the visitor requested.
+		// Two shapes count as a miss: an unmatched route rendering the error
+		// page with status 404, and a matched route answering a content miss
+		// with a redirect to /404 (the documented template pattern) — there the
+		// missed path exists only on this first pass, before the browser
+		// follows the redirect. The error page itself is never logged: /404
+		// answers 404 by design and carries no path information.
+		const location = response.headers.get("location");
+		const missedByRedirect =
+			isRedirectCode(response.status) && (location === "/404" || location === "/404/");
+		const missedDirectly = response.status === 404 && pathname !== "/404" && pathname !== "/404/";
+		if (missedDirectly || missedByRedirect) {
 			const referrer = context.request.headers.get("referer") ?? null;
 			const userAgent = context.request.headers.get("user-agent") ?? null;
 			repo

packages/core/tests/unit/astro/middleware-redirect.test.ts

@@ -178,7 +178,7 @@ describe("redirect middleware — issue #808", () => {
 	});
 });
 
-describe("redirect middleware — 404 logging excludes the site error page", () => {
+describe("redirect middleware — 404 logging attributes misses to the requested path", () => {
 	let db: Kysely<Database>;
 
 	beforeEach(async () => {
@@ -192,7 +192,7 @@ describe("redirect middleware — 404 logging excludes the site error page", ()
 		await teardownTestDatabase(db);
 	});
 
-	it("logs a real missing path exactly once", async () => {
+	it("logs an unmatched path exactly once", async () => {
 		const log404 = vi.spyOn(RedirectRepository.prototype, "log404");
 		const { context } = buildContext({ pathname: "/no-such-page" });
 		const next = vi.fn(async () => new Response("not found", { status: 404 }));
@@ -207,6 +207,42 @@ describe("redirect middleware — 404 logging excludes the site error page", ()
 		log404.mockRestore();
 	});
 
+	it("logs a content miss under its real path across the redirect-to-/404 flow", async () => {
+		// The documented template pattern answers a content miss with
+		// Astro.redirect("/404"): the first request is a 302, the browser then
+		// requests /404, which renders with status 404.
+		const log404 = vi.spyOn(RedirectRepository.prototype, "log404");
+
+		const miss = buildContext({ pathname: "/posts/deleted-post" });
+		const redirectNext = vi.fn(
+			async () => new Response(null, { status: 302, headers: { Location: "/404" } }),
+		);
+		await onRequest(miss.context, redirectNext);
+
+		const errorPage = buildContext({ pathname: "/404" });
+		const errorNext = vi.fn(async () => new Response("not found", { status: 404 }));
+		await onRequest(errorPage.context, errorNext);
+
+		expect(log404).toHaveBeenCalledTimes(1);
+		expect(log404).toHaveBeenCalledWith(expect.objectContaining({ path: "/posts/deleted-post" }));
+		await log404.mock.results[0]!.value;
+		const rows = await db.selectFrom("_emdash_404_log").select("path").execute();
+		expect(rows.map((r) => r.path)).toEqual(["/posts/deleted-post"]);
+		log404.mockRestore();
+	});
+
+	it("does not log ordinary redirects", async () => {
+		const log404 = vi.spyOn(RedirectRepository.prototype, "log404");
+		const { context } = buildContext({ pathname: "/moved" });
+		const next = vi.fn(
+			async () => new Response(null, { status: 302, headers: { Location: "/new-home" } }),
+		);
+		await onRequest(context, next);
+
+		expect(log404).not.toHaveBeenCalled();
+		log404.mockRestore();
+	});
+
 	it("does not log the site's own /404 error page render", async () => {
 		const log404 = vi.spyOn(RedirectRepository.prototype, "log404");
 		for (const pathname of ["/404", "/404/"]) {