Give every blog its own Postgres database

A blog is now a database of its own (blog_<sub>) on the same server: one
pg_dump is a complete backup of a blog, one psql restores it, and nothing a
blog's queries do can reach another blog's rows. The control database
(DATABASE_URL) keeps only users and the blog registry (id, owner, subdomain,
db_name); title, tagline and theme move into a one-row settings table next
to the content so the dump really is everything.

db.Cluster holds the control pool plus small, lazily opened per-blog pools.
store.Store (control) hands out a store.BlogStore per blog; every blog_id
parameter and column is gone, the database is the scope. Handlers reach it
through blogStore(r), which resolveBlog puts in the context next to the blog.

Existing data is moved in place by control migration 00006, a Go migration
that runs inside the control transaction: it creates and migrates each blog
database, copies the rows preserving ids, and marks the registry; 00007 then
drops the old tables. Either every blog is moved or the control database is
untouched.

/media/{id} now serves the host's blog only, so dashboard previews on the
root domain use /b/{sub}/media/{id}. Subdomains are capped at 58 chars so
"blog_" + name fits a Postgres identifier. Deleting a user drops their
database. Store.Open resets a blog's pool and retries once so a database
restored under a running app (dropdb --force, createdb, psql) just works.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Sd8UPWrvyYCLj97JexNw3A

2 files changed, 5 insertions, 5 deletions

diff --git a/internal/web/templates/dashboard/design.html b/internal/web/templates/dashboard/design.html
index 4c86c79..9c2a12f 100644
--- a/internal/web/templates/dashboard/design.html
+++ b/internal/web/templates/dashboard/design.html
@@ -34,7 +34,7 @@
       <option value="tile"{{if eq $t.BgMode "tile"}} selected{{end}}>Repeat (tile)</option>
     </select></label>
   </div>
-  {{template "imagepick" (dict "name" "bg_image" "current" $t.BgImage "images" .Data.images "label" "Background image")}}
+  {{template "imagepick" (dict "name" "bg_image" "current" $t.BgImage "sub" .Blog.Subdomain "images" .Data.images "label" "Background image")}}
 </div>
 
 <div class="card" id="text">
@@ -102,7 +102,7 @@
     </select></label>
   </div>
   <p class="muted small">The title, logo and menu are header modules — add, remove and order them on the <a href="/b/{{.Blog.Subdomain}}/layout#header">Layout</a> tab. The banner below is shown across the top of the header whenever one is chosen.</p>
-  {{template "imagepick" (dict "name" "header_image" "current" $t.HeaderImage "images" .Data.images "label" "Header image (banner)")}}
+  {{template "imagepick" (dict "name" "header_image" "current" $t.HeaderImage "sub" .Blog.Subdomain "images" .Data.images "label" "Header image (banner)")}}
 </div>
 
 <div class="card" id="menu">
@@ -161,8 +161,8 @@
       <option value="large"{{if eq $t.LogoSize "large"}} selected{{end}}>Large (140 px)</option>
     </select></label>
   </div>
-  {{template "imagepick" (dict "name" "logo" "current" $t.Logo "images" .Data.images "label" "Logo" "hint" "Shown wherever you place a Logo module (Layout tab); it links to your front page.")}}
-  {{template "imagepick" (dict "name" "favicon" "current" $t.Favicon "images" .Data.images "label" "Favicon" "hint" "The small icon browsers show in the tab. A square PNG or ICO of 32–64 px works best; pick None for the Blogspace icon." "accept" "image/png,image/x-icon,image/gif,image/webp,image/jpeg,.ico")}}
+  {{template "imagepick" (dict "name" "logo" "current" $t.Logo "sub" .Blog.Subdomain "images" .Data.images "label" "Logo" "hint" "Shown wherever you place a Logo module (Layout tab); it links to your front page.")}}
+  {{template "imagepick" (dict "name" "favicon" "current" $t.Favicon "sub" .Blog.Subdomain "images" .Data.images "label" "Favicon" "hint" "The small icon browsers show in the tab. A square PNG or ICO of 32–64 px works best; pick None for the Blogspace icon." "accept" "image/png,image/x-icon,image/gif,image/webp,image/jpeg,.ico")}}
 </div>
 
 <div class="savebar">
diff --git a/internal/web/templates/dashboard/images.html b/internal/web/templates/dashboard/images.html
index 1c64391..2e39531 100644
--- a/internal/web/templates/dashboard/images.html
+++ b/internal/web/templates/dashboard/images.html
@@ -14,7 +14,7 @@
 <div class="gallery">
 {{range .Data.images}}
   <div class="card thumb">
-    <a href="/media/{{.ID}}" target="_blank"><img src="/media/{{.ID}}" alt="{{.Filename}}"></a>
+    <a href="/b/{{$.Blog.Subdomain}}/media/{{.ID}}" target="_blank"><img src="/b/{{$.Blog.Subdomain}}/media/{{.ID}}" alt="{{.Filename}}"></a>
     <div class="meta">{{.Filename}} <span class="muted">({{kb .Size}})</span></div>
     <input class="copy" readonly value="![{{.Filename}}](/media/{{.ID}})" onclick="this.select()">
     <form method="post" action="/b/{{$.Blog.Subdomain}}/images/{{.ID}}/delete" class="inline"><input type="hidden" name="_csrf" value="{{$.CSRF}}"><button class="mini danger">delete</button></form>