Add robots.txt and sitemap.xml; tidy essay-route prefix-strip

- Emit a minimal robots.txt that points at the sitemap.
- Emit sitemap.xml covering every dated content page (essays, blog,
  fiction, poetry, music) with absolute <loc> and frontmatter-derived
  <lastmod>. Standalone pages (about, colophon, etc.) are
  intentionally omitted: they're reachable via the main nav, lack
  date: frontmatter, and would force a fallback lastmod that
  misrepresents staleness.
- Replace the magic 'drop 8' offset in essay routing with
  stripPrefix "content/". Same behavior, but reads structurally and
  fails closed if the prefix ever changes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

build/Site.hs

@@ -4,7 +4,7 @@ module Site (rules) where
 
 import Control.Monad (forM, forM_, when)
 import Data.Char     (isSpace, toUpper)
-import Data.List     (groupBy, isPrefixOf, sort, sortBy)
+import Data.List     (groupBy, isPrefixOf, sort, sortBy, stripPrefix)
 import Data.Map.Strict (Map)
 import Data.Maybe    (catMaybes, fromMaybe, listToMaybe)
 import Data.Ord      (Down (..), comparing)
@@ -383,13 +383,14 @@ rules = do
                 fname    = takeFileName fp
                 isIndex  = fname == "index.md"
                 isDraft  = "content/drafts/essays/" `isPrefixOf` fp
+                stripContent = fromMaybe fp (stripPrefix "content/" fp)
             in case (isDraft, isIndex) of
                 -- content/drafts/essays/slug/index.md → drafts/essays/slug/index.html
-                (True,  True)  -> replaceExtension (drop 8 fp) "html"
+                (True,  True)  -> replaceExtension stripContent "html"
                 -- content/drafts/essays/foo.md        → drafts/essays/foo.html
                 (True,  False) -> "drafts/essays/" ++ replaceExtension fname "html"
                 -- content/essays/slug/index.md        → essays/slug/index.html
-                (False, True)  -> replaceExtension (drop 8 fp) "html"
+                (False, True)  -> replaceExtension stripContent "html"
                 -- content/essays/foo.md               → essays/foo.html
                 (False, False) -> "essays/" ++ replaceExtension fname "html"
         compile $ essayCompiler
@@ -919,6 +920,49 @@ rules = do
                     <> defaultContext
             renderAtom musicFeedConfig feedCtx compositions
 
+    -- ---------------------------------------------------------------------------
+    -- robots.txt — minimal, just points crawlers at the sitemap
+    -- ---------------------------------------------------------------------------
+    create ["robots.txt"] $ do
+        route idRoute
+        compile $ makeItem $ unlines
+            [ "User-agent: *"
+            , "Allow: /"
+            , ""
+            , "Sitemap: https://levineuwirth.org/sitemap.xml"
+            ]
+
+    -- ---------------------------------------------------------------------------
+    -- sitemap.xml — every dated content page (essays, blog, poetry, fiction,
+    -- music). Standalone pages (about, colophon, etc.) are intentionally
+    -- omitted: they're reachable via the main nav, lack `date:` frontmatter,
+    -- and would force a fallback lastmod that misrepresents staleness.
+    -- ---------------------------------------------------------------------------
+    create ["sitemap.xml"] $ do
+        route idRoute
+        compile $ do
+            entries <- recentFirst
+                        =<< loadAllSnapshots
+                                (   (    allEssays
+                                    .||. "content/blog/*.md"
+                                    .||. "content/fiction/*.md"
+                                    .||. allPoetry
+                                    .||. "content/music/*/index.md"
+                                    )
+                                .&&. hasNoVersion
+                                )
+                                "content"
+            let siteRoot = "https://levineuwirth.org"
+                sitemapItemCtx =
+                    constField "root" siteRoot
+                    <> dateField "lastmod" "%Y-%m-%d"
+                    <> defaultContext
+                sitemapCtx =
+                    constField "root" siteRoot
+                    <> listField "entries" sitemapItemCtx (return entries)
+            makeItem ("" :: String)
+                >>= loadAndApplyTemplate "templates/sitemap.xml" sitemapCtx
+
 -- ---------------------------------------------------------------------------
 -- Epistemic metadata extraction
 -- ---------------------------------------------------------------------------

templates/sitemap.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+  <url>
+    <loc>$root$/</loc>
+  </url>
+$for(entries)$
+  <url>
+    <loc>$root$$url$</loc>
+$if(lastmod)$    <lastmod>$lastmod$</lastmod>
+$endif$  </url>
+$endfor$
+</urlset>