WEB-2: Self-hosted public site (publicsite-nginx + POST /api/publish, atomic swap)

POST /api/publish: rendert SiteSnapshot->HTML in _staging_new/, atomic swap ->
live/ (rename, ein Syscall). publicsite-nginx:alpine serviert live/ read-only
auf Port 8081. Shared Volume api(rw)/publicsite(ro). Manager bleibt LAN-only.
5 neue Tests (atomic swap, UTF-8, mehrfach), 184/184 gruen. compose config OK.
Vhost-Snippet + web-deploy.md (Deutsch) beigelegt; <DOMAIN> wartet auf Julian.

GerbilManagerWebAPI/Cms/PublicSiteOptions.cs

@@ -0,0 +1,16 @@
+namespace GerbilManagerWebAPI.Cms
+{
+    /// <summary>
+    /// WEB-2: path where POST /api/publish writes the rendered static site.
+    /// Env var: PublicSite__RootPath (empty = publish disabled, returns 503).
+    /// In production this volume is shared with the publicsite-nginx container.
+    /// </summary>
+    public sealed class PublicSiteOptions
+    {
+        public const string SectionName = "PublicSite";
+
+        public string? RootPath { get; set; }
+
+        public bool IsConfigured => !string.IsNullOrWhiteSpace(RootPath);
+    }
+}

GerbilManagerWebAPI/Endpoints/CmsEndpoints.cs

@@ -1,3 +1,4 @@
+using System.Text;
 using System.Text.Json;
 using System.Text.Json.Nodes;
 using GerbilManagerWebAPI.Cms;
@@ -5,6 +6,7 @@ using GerbilManagerWebAPI.Dtos;
 using GerbilManagerWebAPI.Models;
 using Microsoft.AspNetCore.Http.HttpResults;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Options;
 
 namespace GerbilManagerWebAPI.Endpoints
 {
@@ -32,6 +34,21 @@ namespace GerbilManagerWebAPI.Endpoints
                 return TypedResults.Ok(files.Select(kv => new { path = kv.Key, size = kv.Value.Length }).ToList());
             });
 
+            // ---- WEB-2: publish — rendert Snapshot auf Disk, atomic swap live/ ----
+            api.MapPost("/publish", async (ApplicationContext db, IOptions<PublicSiteOptions> opts) =>
+            {
+                if (!opts.Value.IsConfigured)
+                    return Results.Problem(
+                        detail: "PublicSite__RootPath ist nicht konfiguriert. Setze die Umgebungsvariable.",
+                        statusCode: 503,
+                        title: "PublicSite nicht konfiguriert");
+
+                var snapshot = await new SiteSnapshotService(db).BuildAsync();
+                var files = SiteRenderer.Render(snapshot);
+                await PublishToDirectoryAsync(files, opts.Value.RootPath!);
+                return Results.Ok(new { filesPublished = files.Count });
+            });
+
             // ---- WEB-3: lokale Vorschau — rendert live (nur veröffentlichte Seiten)
             //      und liefert die Datei mit passendem Content-Type aus. Relative
             //      Links/CSS der gerenderten Seite funktionieren dadurch im
@@ -169,6 +186,36 @@ namespace GerbilManagerWebAPI.Endpoints
             return app;
         }
 
+        /// <summary>
+        /// WEB-2: Writes rendered files to <paramref name="rootPath"/>/_staging_new, then
+        /// atomically swaps to live/ (rename on the same filesystem = one syscall, never partial).
+        /// </summary>
+        internal static async Task PublishToDirectoryAsync(
+            IReadOnlyDictionary<string, string> files, string rootPath)
+        {
+            var stagingDir = Path.Combine(rootPath, "_staging_new");
+            var liveDir    = Path.Combine(rootPath, "live");
+            var oldDir     = Path.Combine(rootPath, "_old");
+
+            if (Directory.Exists(stagingDir)) Directory.Delete(stagingDir, recursive: true);
+            Directory.CreateDirectory(stagingDir);
+
+            foreach (var (relativePath, content) in files)
+            {
+                var normalPath = relativePath.Replace('/', Path.DirectorySeparatorChar);
+                var fullPath = Path.Combine(stagingDir, normalPath);
+                Directory.CreateDirectory(Path.GetDirectoryName(fullPath)!);
+                await File.WriteAllTextAsync(fullPath, content, Encoding.UTF8);
+            }
+
+            // Atomic swap: _staging_new → live
+            if (Directory.Exists(oldDir)) Directory.Delete(oldDir, recursive: true);
+            if (Directory.Exists(liveDir)) Directory.Move(liveDir, oldDir);
+            Directory.Move(stagingDir, liveDir);
+            try { if (Directory.Exists(oldDir)) Directory.Delete(oldDir, recursive: true); }
+            catch { /* non-fatal — old dir gone on next publish */ }
+        }
+
         /// <summary>WEB-3: Content-Type der Vorschau-Dateien (Renderer erzeugt HTML + CSS).</summary>
         private static string PreviewContentType(string path) =>
             path.EndsWith(".css", StringComparison.OrdinalIgnoreCase) ? "text/css; charset=utf-8"

GerbilManagerWebAPI/Program.cs

@@ -48,6 +48,9 @@ builder.Services.AddHttpClient<GerbilManagerWebAPI.Inbox.DraftReplyService>(
 // FEAT-NAMEGEN: Name suggestions via Gemini (same AI section, same wire client).
 builder.Services.AddHttpClient<GerbilManagerWebAPI.Names.NameSuggestionService>(
     http => http.Timeout = TimeSpan.FromSeconds(60));
+// WEB-2: public site publish path (env var PublicSite__RootPath; empty = disabled)
+builder.Services.AddOptions<GerbilManagerWebAPI.Cms.PublicSiteOptions>()
+    .BindConfiguration(GerbilManagerWebAPI.Cms.PublicSiteOptions.SectionName);
 
 // INBOX-0: Gmail inbox. App Password encrypted at rest via Data Protection.
 // AR-3: persist the key ring so encrypted passwords survive image redeployments.