Improve mobile editing

main.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	"context"
+	"crypto/sha256"
 	"embed"
+	"encoding/hex"
 	"flag"
 	"html/template"
 	"io/fs"
@@ -19,9 +21,26 @@ import (
 //go:embed assets
 var assets embed.FS
 
+// editorBundleVersion is a short content hash of the vendored CodeMirror bundle,
+// appended as ?v=… to its <script> src. The bundle is served immutable under a
+// stable filename, so without this query a rebuilt bundle would never reach a
+// client that already cached the old one (this is the editor cache-bust knob).
+var editorBundleVersion = hashAsset("assets/editor/vendor/codemirror.bundle.js")
+
+func hashAsset(name string) string {
+	b, err := assets.ReadFile(name)
+	if err != nil {
+		return ""
+	}
+	sum := sha256.Sum256(b)
+	return hex.EncodeToString(sum[:])[:12]
+}
+
 var (
-	pageTmpl   = template.Must(template.ParseFS(assets, "assets/layout.html", "assets/page/main.html"))
-	editTmpl   = template.Must(template.ParseFS(assets, "assets/layout.html", "assets/editor/main.html"))
+	pageTmpl = template.Must(template.ParseFS(assets, "assets/layout.html", "assets/page/main.html"))
+	editTmpl = template.Must(template.New("edit").Funcs(template.FuncMap{
+		"editorBundleVersion": func() string { return editorBundleVersion },
+	}).ParseFS(assets, "assets/layout.html", "assets/editor/main.html"))
 	searchTmpl = template.Must(template.ParseFS(assets, "assets/layout.html", "assets/search/main.html"))
 )