Add the Layout tab: five areas with modules, columns and a menu editor

A blog page is now header, left column, main content, right column and
footer, each holding an ordered list of modules (blog title, logo, menu,
archive by year/month, recent posts, custom HTML, footer text, RSS link,
site map). Side columns have percentage widths, can be hidden, and can
keep their space when empty; on phones they stack under the posts. The
menu becomes its own ordered list mixing pages and outside links.
Announcements are placed per column at its top or bottom.

Modules and menu items get tables; the migration derives them from each
blog's old theme (nav position, footer text, show-in-nav pages) so
existing blogs look the same. Custom HTML is deliberately stored and
served as-is (owner's decision; see AGENTS.md for why the blast radius
is the blogger's own origin).

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

2 files changed, 69 insertions, 0 deletions

diff --git a/internal/db/migrations/00003_layout.sql b/internal/db/migrations/00003_layout.sql
new file mode 100644
index 0000000..e8fff23
--- /dev/null
+++ b/internal/db/migrations/00003_layout.sql
@@ -0,0 +1,56 @@
+-- +goose Up
+-- Layout modules: what each area of a blog (header, columns, footer) shows.
+CREATE TABLE modules (
+    id          bigserial PRIMARY KEY,
+    blog_id     bigint NOT NULL REFERENCES blogs(id) ON DELETE CASCADE,
+    area        text NOT NULL CHECK (area IN ('header', 'left', 'right', 'above', 'below', 'footer')),
+    kind        text NOT NULL CHECK (kind IN ('title', 'logo', 'menu', 'archive', 'recent', 'html', 'rss', 'text', 'sitemap')),
+    title       text NOT NULL DEFAULT '',
+    body        text NOT NULL DEFAULT '',
+    count       integer NOT NULL DEFAULT 5,
+    sort_order  integer NOT NULL DEFAULT 0,
+    created_at  timestamptz NOT NULL DEFAULT now(),
+    updated_at  timestamptz NOT NULL DEFAULT now()
+);
+CREATE INDEX modules_blog ON modules (blog_id, area, sort_order, id);
+
+-- The menu: blog pages and custom links in one ordered list.
+CREATE TABLE menu_items (
+    id          bigserial PRIMARY KEY,
+    blog_id     bigint NOT NULL REFERENCES blogs(id) ON DELETE CASCADE,
+    page_id     bigint REFERENCES pages(id) ON DELETE CASCADE,
+    label       text NOT NULL DEFAULT '',
+    url         text NOT NULL DEFAULT '',
+    sort_order  integer NOT NULL DEFAULT 0,
+    CHECK (page_id IS NOT NULL OR url <> '')
+);
+CREATE UNIQUE INDEX menu_items_page ON menu_items (page_id) WHERE page_id IS NOT NULL;
+CREATE INDEX menu_items_blog ON menu_items (blog_id, sort_order, id);
+
+-- Existing blogs keep the menu they had: pages marked "show in menu", in menu
+-- order, with the home page only if the theme included it.
+INSERT INTO menu_items (blog_id, page_id, sort_order)
+SELECT p.blog_id, p.id, row_number() OVER (PARTITION BY p.blog_id ORDER BY p.nav_order, p.id) - 1
+FROM pages p JOIN blogs b ON b.id = p.blog_id
+WHERE p.show_in_nav AND (NOT p.is_home OR coalesce((b.theme->>'nav_show_home')::boolean, true));
+ALTER TABLE pages DROP COLUMN show_in_nav;
+
+-- ...and the layout their theme described.
+INSERT INTO modules (blog_id, area, kind, sort_order)
+SELECT id, 'header', 'title', CASE WHEN theme->>'nav_position' = 'top-bar' THEN 1 ELSE 0 END
+FROM blogs WHERE coalesce((theme->>'header_show_title')::boolean, true);
+INSERT INTO modules (blog_id, area, kind, sort_order)
+SELECT id, 'header', 'menu', CASE WHEN theme->>'nav_position' = 'top-bar' THEN 0 ELSE 1 END
+FROM blogs WHERE coalesce(theme->>'nav_position', 'below-header') <> 'left-sidebar';
+INSERT INTO modules (blog_id, area, kind, sort_order)
+SELECT id, 'left', 'menu', 0 FROM blogs WHERE theme->>'nav_position' = 'left-sidebar';
+INSERT INTO modules (blog_id, area, kind, body, sort_order)
+SELECT id, 'footer', 'text', theme->>'footer_text', 0 FROM blogs WHERE coalesce(theme->>'footer_text', '') <> '';
+INSERT INTO modules (blog_id, area, kind, sort_order)
+SELECT id, 'footer', 'rss', 1 FROM blogs WHERE coalesce((theme->>'footer_show_rss')::boolean, true);
+
+-- +goose Down
+ALTER TABLE pages ADD COLUMN show_in_nav boolean NOT NULL DEFAULT true;
+UPDATE pages SET show_in_nav = EXISTS (SELECT 1 FROM menu_items m WHERE m.page_id = pages.id);
+DROP TABLE menu_items;
+DROP TABLE modules;
diff --git a/internal/db/migrations/00004_section_placement.sql b/internal/db/migrations/00004_section_placement.sql
new file mode 100644
index 0000000..c36787e
--- /dev/null
+++ b/internal/db/migrations/00004_section_placement.sql
@@ -0,0 +1,13 @@
+-- +goose Up
+-- Announcements are placed in a column (left, main, right) at its top or bottom.
+ALTER TABLE sections DROP CONSTRAINT sections_placement_check;
+UPDATE sections SET placement = CASE placement WHEN 'above' THEN 'main-top' WHEN 'below' THEN 'main-bottom' ELSE 'left-top' END;
+ALTER TABLE sections ALTER COLUMN placement SET DEFAULT 'main-top';
+ALTER TABLE sections ADD CONSTRAINT sections_placement_check
+    CHECK (placement IN ('left-top', 'left-bottom', 'main-top', 'main-bottom', 'right-top', 'right-bottom'));
+
+-- +goose Down
+ALTER TABLE sections DROP CONSTRAINT sections_placement_check;
+UPDATE sections SET placement = CASE placement WHEN 'main-top' THEN 'above' WHEN 'main-bottom' THEN 'below' ELSE 'sidebar' END;
+ALTER TABLE sections ALTER COLUMN placement SET DEFAULT 'above';
+ALTER TABLE sections ADD CONSTRAINT sections_placement_check CHECK (placement IN ('above', 'below', 'sidebar'));