fix(mime): register application/manifest+json for .webmanifest (+ webp/avif); v1.7.1

Go's MIME table has no .webmanifest entry, so http.FileServer sniffed the PWA web
app manifest as text/plain. mime.AddExtensionType at package load makes TypeByExtension
authoritative. A correctness nit (the manifest spec parses by content and nosniff does
not reject manifests), but a PWA server should label its manifest correctly.

CHANGELOG.md

@@ -6,6 +6,17 @@ This module adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html
 
 ---
 
+## [1.7.1] — 2026-08-14
+
+Patch — correct MIME types for PWA assets.
+
+### Fixed
+
+- Register `application/manifest+json` for `.webmanifest` (plus `image/webp` and `image/avif`) at
+  startup. Without it, Go's content sniffing served the PWA web app manifest as `text/plain`.
+  Nothing broke in practice — the manifest spec parses by content, and `nosniff` does not reject
+  manifests — but a PWA-focused server should label its manifest correctly.
+
 ## [1.7.0] — 2026-08-14
 
 Minor — HTTP behaviour: caching, a strict SPA fallback, security headers, and a non-root image.

README.md

@@ -1,6 +1,6 @@
 # einherjar/spa-server
 
-[![version](https://img.shields.io/badge/version-v1.7.0-5C4EE5?style=flat-square)](https://code.nochebuena.dev/einherjar/spa-server)
+[![version](https://img.shields.io/badge/version-v1.7.1-5C4EE5?style=flat-square)](https://code.nochebuena.dev/einherjar/spa-server)
 [![license](https://img.shields.io/badge/license-AGPL--3.0-22863A?style=flat-square)](LICENSE)
 [![go](https://img.shields.io/badge/Go-1.26+-00ADD8?style=flat-square&logo=go&logoColor=white)](https://go.dev)
 
@@ -15,7 +15,7 @@ The module ships as a ready-to-use Docker base image. Deploying a SPA to a conta
 ## Container usage
 
 ```dockerfile
-FROM code.nochebuena.dev/einherjar/spa-server:v1.7.0
+FROM code.nochebuena.dev/einherjar/spa-server:v1.7.1
 COPY dist/ /srv/www/
 ```
 
@@ -29,7 +29,7 @@ at the root of `dist/`. **Angular**'s application builder instead emits
 at the root and every request falls through to a 404:
 
 ```dockerfile
-FROM code.nochebuena.dev/einherjar/spa-server:v1.7.0
+FROM code.nochebuena.dev/einherjar/spa-server:v1.7.1
 COPY dist/my-app/browser/ /srv/www/
 ```
 

go.mod

@@ -3,6 +3,6 @@ module code.nochebuena.dev/einherjar/spa-server
 go 1.26
 
 require (
-	code.nochebuena.dev/einherjar/contracts v1.7.0
+	code.nochebuena.dev/einherjar/contracts v1.7.1
-	code.nochebuena.dev/einherjar/core v1.7.0
+	code.nochebuena.dev/einherjar/core v1.7.1
 )

go.sum

@@ -1,4 +1,4 @@
-code.nochebuena.dev/einherjar/contracts v1.7.0 h1:yhbtmvE8u6KXcuG95p888+4tDIiTXDf5z/siKrjGbrc=
+code.nochebuena.dev/einherjar/contracts v1.7.1 h1:9FEW1HP+osiZT1OQE4gE9QAafIkvLSja0pRmSWX8gyA=
-code.nochebuena.dev/einherjar/contracts v1.7.0/go.mod h1:ccltUtrFb5+MEJdkx2VVEUL+xC5pupVlVVsMM8AlCWI=
+code.nochebuena.dev/einherjar/contracts v1.7.1/go.mod h1:ccltUtrFb5+MEJdkx2VVEUL+xC5pupVlVVsMM8AlCWI=
-code.nochebuena.dev/einherjar/core v1.7.0 h1:gdjNEgO8E/ALppyBldj27iKQQlWbL/OWV6asdxWLXqU=
+code.nochebuena.dev/einherjar/core v1.7.1 h1:NJZSx6hBVFUGbvPZ2X/WSiwzI//e5zR4AhSqA2ufvsM=
-code.nochebuena.dev/einherjar/core v1.7.0/go.mod h1:IvSCG7XL4gNyoylwlClKj3jepWBLAKb2QKAgumTRkug=
+code.nochebuena.dev/einherjar/core v1.7.1/go.mod h1:hhCB05RXJ5z4yZbfupeil130lAFnEJM/xPdqhfudCVA=

spa/handler_test.go

@@ -6,6 +6,7 @@ import (
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"code.nochebuena.dev/einherjar/contracts/logging"
@@ -24,6 +25,7 @@ func newTestHandler(t *testing.T) http.Handler {
 		"main.4f8a2b1c.js":     "console.log(1)",
 		"favicon.ico":          "icon",
 		"ngsw.json":            "{}",
+		"manifest.webmanifest": `{"name":"app"}`,
 	} {
 		if err := os.WriteFile(filepath.Join(dir, name), []byte(body), 0o644); err != nil {
 			t.Fatal(err)
@@ -107,6 +109,18 @@ func TestFallback_RootServesIndex(t *testing.T) {
 	}
 }
 
+func TestManifestContentType(t *testing.T) {
+	// Without the mime registration this is sniffed as text/plain; with it the
+	// PWA manifest carries its registered type.
+	rec := get(newTestHandler(t), "/manifest.webmanifest", "*/*")
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", rec.Code)
+	}
+	if ct := rec.Header().Get("Content-Type"); !strings.HasPrefix(ct, "application/manifest+json") {
+		t.Errorf("Content-Type = %q, want application/manifest+json", ct)
+	}
+}
+
 func TestIsHashed(t *testing.T) {
 	hashed := []string{"main.4f8a2b1c.js", "index-DkJf3x9a.js", "styles-4NDEUD5S.css", "app.a1b2c3d4.mjs"}
 	plain := []string{"favicon.ico", "index.html", "logo.png", "about.js", "main.js", "vendor.css"}

spa/mime.go

@@ -0,0 +1,24 @@
+package spa
+
+import "mime"
+
+// Go's built-in MIME table — and a container image without /etc/mime.types — has no
+// entry for these extensions, so http.FileServer falls back to content sniffing and
+// mislabels them. The one that matters for a PWA server is the web app manifest,
+// sniffed as text/plain instead of application/manifest+json. Registering the types
+// once at package load makes mime.TypeByExtension authoritative, so the correct
+// Content-Type is sent and no sniffing fallback runs.
+//
+// This is a correctness nit, not a fix for a live break: the manifest spec parses by
+// content (valid JSON) rather than declared type, so browsers accept it either way.
+// A PWA-focused server should still label it correctly. .webp/.avif get the same
+// treatment for the same reason.
+func init() {
+	for ext, typ := range map[string]string{
+		".webmanifest": "application/manifest+json",
+		".webp":        "image/webp",
+		".avif":        "image/avif",
+	} {
+		_ = mime.AddExtensionType(ext, typ)
+	}
+}