diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,5 @@
+# Revision history for ema-extra
+
+## 0.10.0.0 (2022-11-20)
+
+- Split from `ema` package
diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
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+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published
+    by the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If your software can interact with users remotely through a computer
+network, you should also make sure that it provides a way for users to
+get its source.  For example, if your program is a web application, its
+interface could display a "Source" link that leads users to an archive
+of the code.  There are many ways you could offer source, and different
+solutions will be better for different programs; see section 13 for the
+specific requirements.
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU AGPL, see
+<https://www.gnu.org/licenses/>.
diff --git a/README.md b/README.md
new file mode 100644
--- /dev/null
+++ b/README.md
@@ -0,0 +1,3 @@
+# ema-extra
+
+Useful route types for [Ema](https://ema.srid.ca/)
diff --git a/ema-extra.cabal b/ema-extra.cabal
new file mode 100644
--- /dev/null
+++ b/ema-extra.cabal
@@ -0,0 +1,111 @@
+cabal-version:      2.4
+name:               ema-extra
+version:            0.10.0.0
+license:            AGPL-3.0-only
+copyright:          2022 Sridhar Ratnakumar
+maintainer:         srid@srid.ca
+author:             Sridhar Ratnakumar
+category:           Web
+synopsis:           Useful route types for Ema
+bug-reports:        https://github.com/srid/ema/issues
+homepage:           https://ema.srid.ca/
+description:        Useful route types for Ema
+extra-source-files:
+  CHANGELOG.md
+  LICENSE
+  README.md
+
+common extensions
+  default-extensions:
+    NoStarIsType
+    BangPatterns
+    ConstraintKinds
+    DataKinds
+    DeriveDataTypeable
+    DeriveFoldable
+    DeriveFunctor
+    DeriveGeneric
+    DeriveLift
+    DeriveTraversable
+    DerivingStrategies
+    DerivingVia
+    EmptyCase
+    EmptyDataDecls
+    EmptyDataDeriving
+    ExistentialQuantification
+    ExplicitForAll
+    FlexibleContexts
+    FlexibleInstances
+    GADTSyntax
+    GeneralisedNewtypeDeriving
+    ImportQualifiedPost
+    KindSignatures
+    LambdaCase
+    MultiParamTypeClasses
+    MultiWayIf
+    NumericUnderscores
+    OverloadedStrings
+    PolyKinds
+    PostfixOperators
+    RankNTypes
+    ScopedTypeVariables
+    StandaloneDeriving
+    StandaloneKindSignatures
+    TupleSections
+    TypeApplications
+    TypeFamilies
+    TypeOperators
+    ViewPatterns
+
+library
+  import:           extensions
+
+  -- Modules included in this executable, other than Main.
+  -- other-modules:
+
+  -- LANGUAGE extensions used by modules in this package.
+  -- other-extensions:
+  build-depends:
+    , base           >=4.13.0.0 && <4.17.0.0.0
+    , containers
+    , data-default
+    , dependent-sum
+    , ema
+    , ema-generics
+    , filepath
+    , generics-sop
+    , monad-logger
+    , optics-core
+    , pandoc
+    , relude         >=1.0
+    , sop-core
+    , text
+    , time
+    , unionmount
+    , unliftio
+    , url-slug
+
+  mixins:
+    base hiding (Prelude),
+    relude (Relude as Prelude, Relude.Container.One),
+    relude
+
+  ghc-options:
+    -Wall -Wincomplete-record-updates -Wincomplete-uni-patterns
+    -Wmissing-deriving-strategies -Wunused-foralls -Wunused-foralls
+    -fprint-explicit-foralls -fprint-explicit-kinds
+    -fprint-potential-instances
+
+  exposed-modules:
+    Ema.Route.Lib.Extra.MapRoute
+    Ema.Route.Lib.Extra.PaginatedRoute
+    Ema.Route.Lib.Extra.PandocRoute
+    Ema.Route.Lib.Extra.SlugRoute
+    Ema.Route.Lib.Extra.StaticRoute
+    Ema.Route.Lib.Extra.StringRoute
+
+  hs-source-dirs:   src
+  default-language: Haskell2010
+
+  if impl(ghc >=8.10)
+    ghc-options: -Wunused-packages
diff --git a/src/Ema/Route/Lib/Extra/MapRoute.hs b/src/Ema/Route/Lib/Extra/MapRoute.hs
new file mode 100644
--- /dev/null
+++ b/src/Ema/Route/Lib/Extra/MapRoute.hs
@@ -0,0 +1,57 @@
+{-# LANGUAGE DeriveAnyClass #-}
+
+module Ema.Route.Lib.Extra.MapRoute (
+  MapRoute (MapRoute),
+) where
+
+import Data.Map.Strict qualified as Map
+import Data.Maybe (fromJust)
+import Data.Text qualified as T
+import Ema.Route.Class (IsRoute (..))
+import Ema.Route.Prism (fromPrism_, toPrism_)
+import Generics.SOP qualified as SOP
+import Optics.Core (preview, prism', review)
+
+{- | Like `FolderRoute` but using dynamic folder name, looked up on a `Map`.
+
+  Empty folder name (map keys) are supported. They would translate in effect to
+  the looked up route (no folder created).
+-}
+newtype MapRoute k r = MapRoute (k, r)
+  deriving stock (Show, Eq, Ord, Generic)
+  deriving anyclass (SOP.Generic, SOP.HasDatatypeInfo)
+
+instance (IsRoute r, IsString k, ToString k, Ord k, Show r) => IsRoute (MapRoute k r) where
+  type RouteModel (MapRoute k r) = Map k (RouteModel r)
+  routePrism rs =
+    -- TODO: Reimplement using optics composition
+    toPrism_ $
+      prism'
+        ( \(MapRoute (k, r)) ->
+            let m = fromJust $ Map.lookup k rs -- HACK: fromJust
+                prefix = if toString k == "" then "" else toString k <> "/"
+             in prefix <> review (fromPrism_ $ routePrism @r m) r
+        )
+        ( \fp -> do
+            let candidates =
+                  case breakPath fp of
+                    (a, Nothing) -> [("", a)]
+                    (a, Just b) -> [(a, b), ("", fp)]
+            (m, k, rest) <-
+              asum $
+                candidates <&> \(base, rest) ->
+                  let k = fromString base
+                   in (,k,rest) <$> Map.lookup k rs
+            r <- preview (fromPrism_ $ routePrism @r m) (toString rest)
+            pure $ MapRoute (k, r)
+        )
+    where
+      -- Breaks a path once on the first slash.
+      breakPath :: HasCallStack => String -> (String, Maybe [Char])
+      breakPath (s :: String) =
+        case T.breakOn "/" (toText s) of
+          (p, "") -> (toString p, Nothing)
+          (p, toString -> '/' : rest) -> (toString p, Just rest)
+          _ -> error "T.breakOn: impossible"
+
+  routeUniverse rs = concatMap (\(a, m) -> MapRoute . (a,) <$> routeUniverse m) $ Map.toList rs
diff --git a/src/Ema/Route/Lib/Extra/PaginatedRoute.hs b/src/Ema/Route/Lib/Extra/PaginatedRoute.hs
new file mode 100644
--- /dev/null
+++ b/src/Ema/Route/Lib/Extra/PaginatedRoute.hs
@@ -0,0 +1,105 @@
+{-# LANGUAGE DeriveAnyClass #-}
+
+-- | Provides a `Page` type that enables any route to be paginated.
+module Ema.Route.Lib.Extra.PaginatedRoute (
+  -- * Page
+  Page,
+
+  -- * `Page` Functions
+  pageNum,
+  fromNum,
+  pageRange,
+  lookupPage,
+  lookupPage',
+
+  -- * Utility functions
+  paginate,
+) where
+
+import Data.Default (Default (..))
+import Data.Sequence qualified as Seq
+import Data.Text qualified as T
+import Ema.Route.Class (IsRoute (..))
+import Ema.Route.Prism (toPrism_)
+import Generics.SOP qualified as SOP
+import Optics.Core (prism')
+import Text.Show qualified as Show
+
+{- | Represents a single page in a multi-page view/route.
+
+  Use `pageNum` to retrieve the user-facing page number which are 1-index;
+  `fromNum` to convert them back.
+-}
+newtype Page (t :: Type) = Page {unPage :: Word}
+  deriving newtype (Eq, Ord, Num, Enum, Default)
+  deriving stock (Generic)
+  deriving anyclass (SOP.Generic, SOP.HasDatatypeInfo)
+
+instance Show (Page t) where
+  show p = "Page " <> show (pageNum p)
+
+-- | Get the user-facing page number.
+pageNum :: forall a. Page a -> Int
+pageNum (Page n) =
+  fromInteger . toInteger $ n + 1
+
+-- | Convert the user-facing page number.
+fromNum :: forall a. Int -> Maybe (Page a)
+fromNum n = do
+  guard $ n > 0
+  pure $ fromInteger . toInteger $ n - 1
+
+-- | Enumerate list of all pages given the total number of pages.
+pageRange :: forall a. HasCallStack => Int -> NonEmpty (Page a)
+pageRange total =
+  fromMaybe (error "pageRange: total must be positive and non-zero") $ do
+    end <- fromNum @a total
+    nonEmpty [def .. end]
+
+-- | Retrieve the given page from the list.
+lookupPage :: HasCallStack => Page a -> NonEmpty [a] -> [a]
+lookupPage r xs =
+  fromMaybe (error outOfBoundsError) $ lookupPage' r xs
+  where
+    outOfBoundsError =
+      "lookupPage: Page "
+        <> show r
+        <> " is out of bounds of total available pages: "
+        <> show (length xs)
+
+lookupPage' :: Page a -> NonEmpty [a] -> Maybe [a]
+lookupPage' p xs =
+  toList xs !!? (fromInteger . toInteger $ unPage p)
+
+instance IsRoute (Page a) where
+  type RouteModel (Page a) = NonEmpty [a]
+  routePrism m =
+    -- TODO: Refactor this using lens composition.
+    toPrism_ $
+      prism'
+        ( \page ->
+            if page == def
+              then "index.html"
+              else "page/" <> show (pageNum page) <> ".html"
+        )
+        ( \fp -> do
+            if fp == "index.html"
+              then pure def
+              else do
+                page <- fmap toString $ T.stripSuffix ".html" =<< T.stripPrefix "page/" (toText fp)
+                r <- fromNum <=< readMaybe $ page
+                void $ lookupPage' r m -- Check if this page exists
+                pure r
+        )
+  routeUniverse =
+    toList . pageRange . length
+
+-- | Break a list into pages given the page size.
+paginate :: Int -> [a] -> NonEmpty [a]
+paginate pageSize =
+  fromMaybe (one mempty)
+    . nonEmpty
+    . fmap toList
+    . toList
+    . Seq.chunksOf pageSize
+    . Seq.fromList
diff --git a/src/Ema/Route/Lib/Extra/PandocRoute.hs b/src/Ema/Route/Lib/Extra/PandocRoute.hs
new file mode 100644
--- /dev/null
+++ b/src/Ema/Route/Lib/Extra/PandocRoute.hs
@@ -0,0 +1,198 @@
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE UndecidableInstances #-}
+
+module Ema.Route.Lib.Extra.PandocRoute (
+  -- * Route
+  PandocRoute (..),
+  mkPandocRoute,
+
+  -- * Model and Arg
+  Model (..),
+  Arg (..),
+
+  -- * Looking up Pandoc values in model
+  lookupPandocRoute,
+
+  -- * Rendering
+  PandocHtml (..),
+  PandocError (..),
+) where
+
+import Control.Exception (throw, throwIO)
+import Control.Monad.Logger (
+  MonadLogger,
+  MonadLoggerIO,
+  logInfoNS,
+ )
+import Data.Default (Default (..))
+import Data.List qualified as List
+import Data.Map.Strict qualified as Map
+import Data.SOP (I (I), NP (..))
+import Data.Set qualified as Set
+import Ema
+import Ema.CLI qualified
+import Ema.Route.Generic.TH
+import Ema.Route.Lib.Extra.SlugRoute
+import Generics.SOP qualified as SOP
+import System.FilePath ((</>))
+import System.UnionMount qualified as UnionMount
+import Text.Pandoc (Pandoc, ReaderOptions, runIO)
+import Text.Pandoc qualified as Pandoc
+import Text.Pandoc.Sources (ToSources)
+import UnliftIO (MonadUnliftIO)
+
+-- | Represents the relative path to a file that pandoc can parse.
+newtype PandocRoute = PandocRoute {unPandocRoute :: SlugRoute Pandoc}
+  deriving stock (Eq, Ord, Show, Generic)
+  deriving anyclass (SOP.Generic, SOP.HasDatatypeInfo)
+  deriving
+    (HasSubRoutes, IsRoute)
+    via ( GenericRoute
+            PandocRoute
+            '[ WithModel Model
+             , WithSubRoutes
+                '[ SlugRoute Pandoc
+                 ]
+             ]
+        )
+
+instance HasSubModels PandocRoute where
+  subModels m = I (Map.mapKeys unPandocRoute $ modelPandocs m) :* Nil
+
+instance IsString PandocRoute where
+  fromString fp = maybe (error $ "Bad path: " <> toText fp) snd $ mkPandocRoute fp
+
+mkPandocRoute :: FilePath -> Maybe (String, PandocRoute)
+mkPandocRoute fp = do
+  (ext, r) <- mkSlugRoute fp
+  pure (ext, PandocRoute r)
+
+data Model = Model
+  { modelArg :: Arg
+  , modelPandocs :: Map PandocRoute Pandoc
+  }
+  deriving stock (Generic)
+
+lookupPandocRoute :: Model -> PandocRoute -> Maybe (Pandoc, Pandoc -> PandocHtml)
+lookupPandocRoute model r = do
+  pandoc <- Map.lookup r $ modelPandocs model
+  let render = PandocHtml . renderHtml (argWriterOpts $ modelArg model)
+  pure (pandoc, render)
+  where
+    renderHtml :: HasCallStack => Pandoc.WriterOptions -> Pandoc -> Text
+    renderHtml writerSettings pandoc =
+      either (throw . PandocError_RenderError . show) id $
+        Pandoc.runPure $
+          Pandoc.writeHtml5String writerSettings pandoc
+
+data Arg = Arg
+  { -- Base directory
+    argBaseDir :: FilePath
+  , -- Pandoc reader formats supported, as file extension; eg: '.md'
+    argFormats :: Set String
+  , argReaderOpts :: Pandoc.ReaderOptions
+  , argWriterOpts :: Pandoc.WriterOptions
+  }
+  deriving stock (Generic)
+
+instance Default Arg where
+  def = Arg "." formats defaultReaderOpts defaultWriterOpts
+    where
+      formats = Set.fromList knownPandocFormats
+      defaultReaderOpts = def {Pandoc.readerExtensions = exts}
+      defaultWriterOpts = def {Pandoc.writerExtensions = exts}
+      exts :: Pandoc.Extensions
+      exts =
+        -- Sensible defaults for Markdown and others
+        Pandoc.pandocExtensions <> Pandoc.extensionsFromList [Pandoc.Ext_attributes]
+
+instance EmaSite PandocRoute where
+  type SiteArg PandocRoute = Arg
+
+  -- Returns the `Pandoc` AST along with the function that renders it to HTML.
+  type SiteOutput PandocRoute = (Pandoc, Pandoc -> PandocHtml)
+
+  siteInput _ arg = do
+    fmap (Model arg) <$> pandocFilesDyn (argBaseDir arg) (argFormats arg) (argReaderOpts arg)
+  siteOutput _rp model r = do
+    maybe (liftIO $ throwIO $ PandocError_Missing $ show r) pure $ lookupPandocRoute model r
+
+pandocFilesDyn ::
+  forall m.
+  (MonadIO m, MonadUnliftIO m, MonadLogger m, MonadLoggerIO m) =>
+  FilePath ->
+  Set String ->
+  ReaderOptions ->
+  m (Dynamic m (Map PandocRoute Pandoc))
+pandocFilesDyn baseDir formats readerOpts = do
+  let pats =
+        toList formats <&> \ext ->
+          ((), "**/*" <> ext)
+      ignorePats = [".*"]
+      model0 = mempty
+  Dynamic <$> UnionMount.mount baseDir pats ignorePats model0 (const handleUpdate)
+  where
+    -- Take the file that got changed and update our in-memory `Model` accordingly.
+    handleUpdate ::
+      (MonadIO m, MonadLogger m, MonadLoggerIO m) =>
+      FilePath ->
+      UnionMount.FileAction () ->
+      m (Map PandocRoute Pandoc -> Map PandocRoute Pandoc)
+    handleUpdate fp = \case
+      UnionMount.Refresh _ _ -> do
+        mData <- readSource fp
+        pure $ maybe id (uncurry Map.insert) mData
+      UnionMount.Delete ->
+        pure $ maybe id (Map.delete . snd) $ mkPandocRoute fp
+    readSource :: (MonadIO m, MonadLogger m, MonadLoggerIO m) => FilePath -> m (Maybe (PandocRoute, Pandoc))
+    readSource fp = runMaybeT $ do
+      (ext, r :: PandocRoute) <- hoistMaybe (mkPandocRoute fp)
+      guard $ ext `Set.member` formats
+      log $ "Reading " <> toText fp
+      s :: Text <- fmap decodeUtf8 $ readFileBS $ baseDir </> fp
+      liftIO (runIO $ readPandocSource readerOpts ext s) >>= \case
+        Left err -> Ema.CLI.crash "PandocRoute" $ show err
+        Right doc -> do
+          pure (r, doc)
+
+log :: MonadLogger m => Text -> m ()
+log = logInfoNS "PandocRoute"
+
+data PandocError
+  = PandocError_Missing Text
+  | PandocError_RenderError Text
+  deriving stock (Eq, Show)
+  deriving anyclass (Exception)
+
+newtype PandocHtml = PandocHtml {unPandocHtml :: Text}
+  deriving stock (Eq, Generic)
+
+-- Pandoc reader abstraction
+--
+-- TODO: Can we refactor this using,
+-- https://github.com/jgm/pandoc/blob/16f0316fbaa4d667ba40772969ab8e28fea6a493/src/Text/Pandoc/App/FormatHeuristics.hs#L36
+
+knownPandocFormats :: [String]
+knownPandocFormats = [".md", ".org"]
+
+formatFromExt :: String -> Text
+formatFromExt = \case
+  ".md" -> "markdown"
+  ".org" -> "org"
+  ext -> throw $ UnsupportedPandocFormat ext
+
+readPandocSource ::
+  forall m a.
+  (Pandoc.PandocMonad m, ToSources a) =>
+  ReaderOptions ->
+  [Char] ->
+  a ->
+  m Pandoc
+readPandocSource readerOpts ext s =
+  case List.lookup (formatFromExt ext) Pandoc.readers of
+    Just (Pandoc.TextReader f) -> f readerOpts s
+    _ -> throw $ UnsupportedPandocFormat ext
+
+data UnsupportedPandocFormat = UnsupportedPandocFormat String
+  deriving stock (Eq, Show)
+  deriving anyclass (Exception)
diff --git a/src/Ema/Route/Lib/Extra/SlugRoute.hs b/src/Ema/Route/Lib/Extra/SlugRoute.hs
new file mode 100644
--- /dev/null
+++ b/src/Ema/Route/Lib/Extra/SlugRoute.hs
@@ -0,0 +1,40 @@
+module Ema.Route.Lib.Extra.SlugRoute (
+  SlugRoute,
+  mkSlugRoute,
+) where
+
+import Data.Map.Strict qualified as Map
+import Data.Text qualified as T
+import Ema.Route.Class (IsRoute (..))
+import Ema.Route.Prism (htmlSuffixPrism, toPrism_)
+import Network.URI.Slug (Slug)
+import Network.URI.Slug qualified as Slug
+import Optics.Core (prism', (%))
+import System.FilePath (splitExtension, splitPath)
+
+{- | Route to a file that is associated with a value of type `a`.
+
+ A route to foo/bar/qux.md, for instance, is encoded as /foo/bar/qux. ie., the
+ extension is dropped.
+-}
+newtype SlugRoute (a :: Type) = SlugRoute {unSlugRoute :: NonEmpty Slug}
+  deriving stock (Eq, Ord, Show, Generic)
+
+instance IsRoute (SlugRoute a) where
+  type RouteModel (SlugRoute a) = Map (SlugRoute a) a
+  routePrism m =
+    let encode (SlugRoute slugs) =
+          toString $ T.intercalate "/" $ Slug.unSlug <$> toList slugs
+        decode fp = do
+          guard $ not $ null fp
+          slugs <- nonEmpty $ fromString . toString <$> T.splitOn "/" (toText fp)
+          let r = SlugRoute slugs
+          guard $ Map.member r m
+          pure r
+     in toPrism_ $ htmlSuffixPrism % prism' encode decode
+  routeUniverse = Map.keys
+
+mkSlugRoute :: forall a. FilePath -> Maybe (String, SlugRoute a)
+mkSlugRoute (splitExtension -> (relFp, ext')) = do
+  let slugs = fromString . toString . T.dropWhileEnd (== '/') . toText <$> splitPath relFp
+  (ext',) <$> viaNonEmpty SlugRoute slugs
diff --git a/src/Ema/Route/Lib/Extra/StaticRoute.hs b/src/Ema/Route/Lib/Extra/StaticRoute.hs
new file mode 100644
--- /dev/null
+++ b/src/Ema/Route/Lib/Extra/StaticRoute.hs
@@ -0,0 +1,111 @@
+{-# LANGUAGE DeriveAnyClass #-}
+{-# OPTIONS_GHC -Wno-unrecognised-pragmas #-}
+
+{-# HLINT ignore "Use impureThrow" #-}
+
+module Ema.Route.Lib.Extra.StaticRoute (
+  StaticRoute,
+  Model (..),
+
+  -- * Helpers
+  staticRouteUrl,
+) where
+
+import Control.Exception (throw)
+import Control.Monad.Logger (MonadLogger, MonadLoggerIO)
+import Data.List qualified as List
+import Data.Map.Strict qualified as Map
+import Data.Some (Some)
+import Data.Time (UTCTime, defaultTimeLocale, formatTime, getCurrentTime)
+import Ema
+import Ema.CLI qualified
+import GHC.TypeLits (KnownSymbol, Symbol, symbolVal)
+import Optics.Core (Prism', prism')
+import System.FilePath (takeExtension, (</>))
+import System.UnionMount qualified as UnionMount
+import UnliftIO (MonadUnliftIO)
+
+-- | Route to a static file under @baseDir@.
+newtype StaticRoute (baseDir :: Symbol) = StaticRoute {unStaticRoute :: FilePath}
+  deriving newtype (Eq, Ord, Show)
+  deriving stock (Generic)
+
+data Model = Model
+  { modelCliAction :: Some Ema.CLI.Action
+  , modelFiles :: Map FilePath UTCTime
+  }
+  deriving stock (Eq, Show, Generic)
+
+instance IsRoute (StaticRoute baseDir) where
+  type RouteModel (StaticRoute baseDir) = Model
+  routePrism (modelFiles -> files) =
+    let enc =
+          unStaticRoute
+        dec fp =
+          StaticRoute fp <$ guard (Map.member fp files)
+     in toPrism_ $ prism' enc dec
+  routeUniverse (modelFiles -> files) =
+    StaticRoute <$> Map.keys files
+
+instance KnownSymbol baseDir => EmaSite (StaticRoute baseDir) where
+  siteInput cliAct _ = do
+    files <- staticFilesDynamic $ symbolVal (Proxy @baseDir)
+    pure $ Model cliAct <$> files
+  siteOutput _ _ (StaticRoute path) =
+    pure $ Ema.AssetStatic $ symbolVal (Proxy @baseDir) </> path
+
+staticFilesDynamic ::
+  forall m.
+  (MonadIO m, MonadUnliftIO m, MonadLogger m, MonadLoggerIO m) =>
+  FilePath ->
+  m (Dynamic m (Map FilePath UTCTime))
+staticFilesDynamic baseDir = do
+  let pats = [((), "**")]
+      ignorePats = [".*"]
+      model0 = mempty
+  Dynamic <$> UnionMount.mount baseDir pats ignorePats model0 (const handleUpdate)
+  where
+    handleUpdate ::
+      FilePath ->
+      UnionMount.FileAction () ->
+      m (Map FilePath UTCTime -> Map FilePath UTCTime)
+    handleUpdate fp = \case
+      UnionMount.Refresh _ _ -> do
+        lastAccessed <- liftIO getCurrentTime
+        pure $ Map.insert fp lastAccessed
+      UnionMount.Delete -> do
+        pure $ Map.delete fp
+
+-- | Like `Ema.routeUrl`, but looks up the value and appends it to URL in live-server (for force-reload in browser)
+staticRouteUrl ::
+  forall s baseDir.
+  (IsString s, HasCallStack) =>
+  Prism' FilePath (StaticRoute baseDir) ->
+  RouteModel (StaticRoute baseDir) ->
+  FilePath ->
+  s
+staticRouteUrl rp model fp =
+  let lastAccessed = lookupMust fp model
+      tag = toText $ formatTime defaultTimeLocale "%s" lastAccessed
+      url = Ema.routeUrl rp $ StaticRoute fp
+   in fromString . toString $ url <> refreshAddendum tag
+  where
+    -- Force the browser to reload the static file referenced
+    refreshAddendum tag =
+      fromMaybe "" $ do
+        -- In live server, force reload all (re-added/modified) static files.
+        -- In statically generated site, do it only for CSS and JS files.
+        guard $
+          Ema.CLI.isLiveServer (modelCliAction model)
+            || takeExtension fp `List.elem` [".css", ".js"]
+        pure $ "?" <> tag
+
+lookupMust :: FilePath -> Model -> UTCTime
+lookupMust fp model =
+  case Map.lookup fp (modelFiles model) of
+    Just lastAccessed -> lastAccessed
+    Nothing -> throw $ MissingStaticFile fp
+
+newtype MissingStaticFile = MissingStaticFile FilePath
+  deriving stock (Eq, Show)
+  deriving anyclass (Exception)
diff --git a/src/Ema/Route/Lib/Extra/StringRoute.hs b/src/Ema/Route/Lib/Extra/StringRoute.hs
new file mode 100644
--- /dev/null
+++ b/src/Ema/Route/Lib/Extra/StringRoute.hs
@@ -0,0 +1,31 @@
+{-# LANGUAGE DeriveAnyClass #-}
+
+module Ema.Route.Lib.Extra.StringRoute where
+
+import Data.Map.Strict qualified as Map
+import Ema.Route.Class (IsRoute (..))
+import Ema.Route.Prism (htmlSuffixPrism, toPrism_)
+import Generics.SOP qualified as SOP
+import Optics.Core (coercedTo, iso, prism', (%))
+
+{- | A route represented by a stringy type; associated with a Map indexed by
+ same as its model.
+
+ See Ex03_Store.hs for example usage.
+-}
+newtype StringRoute (a :: Type) r = StringRoute {unStringRoute :: r}
+  deriving stock (Show, Eq, Ord, Generic)
+  deriving anyclass (SOP.Generic, SOP.HasDatatypeInfo)
+
+instance (IsString r, ToString r, Eq r, Ord r) => IsRoute (StringRoute a r) where
+  type RouteModel (StringRoute a r) = Map r a
+  routePrism as =
+    toPrism_ $
+      htmlSuffixPrism
+        % iso fromString toString
+        % mapMemberPrism as
+        % coercedTo
+    where
+      mapMemberPrism m =
+        prism' id $ \r -> r <$ guard (r `Map.member` m)
+  routeUniverse as = StringRoute <$> Map.keys as