add URL redirects with ETS-cached plug, broken URL tracking, and admin UI

Redirects context with redirect/broken_url schemas, chain flattening,
ETS cache for fast lookups in the request pipeline. BrokenUrlTracker
plug logs 404s. Auto-redirect on product slug change via upsert_product
hook. Admin redirects page with active/broken tabs, manual create form.
RedirectPrunerWorker cleans up old broken URLs. 1227 tests passing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/berrypod_web/components/layouts/admin.html.heex

@@ -118,6 +118,14 @@
               <.icon name="hero-envelope" class="size-5" /> Email
             </.link>
           </li>
+          <li>
+            <.link
+              navigate={~p"/admin/redirects"}
+              class={admin_nav_active?(@current_path, "/admin/redirects")}
+            >
+              <.icon name="hero-arrow-uturn-right" class="size-5" /> Redirects
+            </.link>
+          </li>
         </ul>
       </nav>
 

lib/berrypod_web/endpoint.ex

@@ -59,5 +59,6 @@ defmodule BerrypodWeb.Endpoint do
   plug Plug.MethodOverride
   plug Plug.Head
   plug Plug.Session, @session_options
-  plug BerrypodWeb.Router
+  plug BerrypodWeb.Plugs.Redirects
+  plug BerrypodWeb.Plugs.BrokenUrlTracker, router: BerrypodWeb.Router
 end

lib/berrypod_web/live/admin/redirects.ex

@@ -0,0 +1,279 @@
+defmodule BerrypodWeb.Admin.Redirects do
+  use BerrypodWeb, :live_view
+
+  alias Berrypod.Redirects
+
+  @valid_tabs ~w(redirects broken create)
+
+  @impl true
+  def mount(_params, _session, socket) do
+    if connected?(socket), do: Redirects.subscribe()
+
+    socket =
+      socket
+      |> assign(:page_title, "Redirects")
+      |> assign(:redirects, Redirects.list_redirects())
+      |> assign(:broken_urls, Redirects.list_broken_urls())
+      |> assign(
+        :form,
+        to_form(%{"from_path" => "", "to_path" => "", "status_code" => "301"}, as: :redirect)
+      )
+
+    {:ok, socket}
+  end
+
+  @impl true
+  def handle_params(params, _uri, socket) do
+    tab = if params["tab"] in @valid_tabs, do: params["tab"], else: "redirects"
+    {:noreply, assign(socket, :tab, tab)}
+  end
+
+  @impl true
+  def handle_info({:redirects_changed, _action}, socket) do
+    {:noreply, assign(socket, :redirects, Redirects.list_redirects())}
+  end
+
+  def handle_info({:broken_urls_changed, _path}, socket) do
+    {:noreply, assign(socket, :broken_urls, Redirects.list_broken_urls())}
+  end
+
+  @impl true
+  def handle_event("switch_tab", %{"tab" => tab}, socket) do
+    {:noreply, push_patch(socket, to: ~p"/admin/redirects?#{%{tab: tab}}")}
+  end
+
+  def handle_event("delete_redirect", %{"id" => id}, socket) do
+    redirect = Redirects.get_redirect!(id)
+    {:ok, _} = Redirects.delete_redirect(redirect)
+
+    {:noreply, assign(socket, :redirects, Redirects.list_redirects())}
+  end
+
+  def handle_event("create_redirect", %{"redirect" => params}, socket) do
+    from_path = params["from_path"]
+
+    case Redirects.create_manual(%{
+           from_path: from_path,
+           to_path: params["to_path"],
+           status_code: String.to_integer(params["status_code"])
+         }) do
+      {:ok, _redirect} ->
+        resolve_matching_broken_url(from_path)
+
+        socket =
+          socket
+          |> assign(
+            :form,
+            to_form(%{"from_path" => "", "to_path" => "", "status_code" => "301"}, as: :redirect)
+          )
+          |> put_flash(:info, "Redirect created")
+          |> push_patch(to: ~p"/admin/redirects?#{%{tab: "redirects"}}")
+
+        {:noreply, socket}
+
+      {:error, changeset} ->
+        {:noreply, assign(socket, :form, to_form(changeset))}
+    end
+  end
+
+  def handle_event("ignore_broken_url", %{"id" => id}, socket) do
+    broken_url = Redirects.get_broken_url!(id)
+    {:ok, _} = Redirects.ignore_broken_url(broken_url)
+
+    {:noreply, assign(socket, :broken_urls, Redirects.list_broken_urls())}
+  end
+
+  def handle_event("redirect_broken_url", %{"path" => path}, socket) do
+    socket =
+      socket
+      |> assign(
+        :form,
+        to_form(%{"from_path" => path, "to_path" => "", "status_code" => "301"}, as: :redirect)
+      )
+      |> push_patch(to: ~p"/admin/redirects?#{%{tab: "create"}}")
+
+    {:noreply, socket}
+  end
+
+  @impl true
+  def render(assigns) do
+    ~H"""
+    <.header>
+      Redirects
+    </.header>
+
+    <div class="flex gap-2 mt-6 mb-4 flex-wrap">
+      <.tab_button tab="redirects" label="Active" count={length(@redirects)} active={@tab} />
+      <.tab_button tab="broken" label="Broken URLs" count={length(@broken_urls)} active={@tab} />
+      <.tab_button tab="create" label="Create" active={@tab} />
+    </div>
+
+    <%= if @tab == "redirects" do %>
+      <.redirects_table redirects={@redirects} />
+    <% end %>
+
+    <%= if @tab == "broken" do %>
+      <.broken_urls_table broken_urls={@broken_urls} />
+    <% end %>
+
+    <%= if @tab == "create" do %>
+      <.create_form form={@form} />
+    <% end %>
+    """
+  end
+
+  defp redirects_table(assigns) do
+    ~H"""
+    <%= if @redirects == [] do %>
+      <p>No redirects yet.</p>
+    <% else %>
+      <table class="admin-table">
+        <thead>
+          <tr>
+            <th>From</th>
+            <th>To</th>
+            <th>Source</th>
+            <th>Hits</th>
+            <th>Created</th>
+            <th></th>
+          </tr>
+        </thead>
+        <tbody>
+          <%= for redirect <- @redirects do %>
+            <tr>
+              <td><code>{redirect.from_path}</code></td>
+              <td><code>{redirect.to_path}</code></td>
+              <td>
+                <span class={"badge badge-#{source_colour(redirect.source)}"}>
+                  {redirect.source}
+                </span>
+              </td>
+              <td>{redirect.hit_count}</td>
+              <td>{Calendar.strftime(redirect.inserted_at, "%d %b %Y")}</td>
+              <td>
+                <button
+                  phx-click="delete_redirect"
+                  phx-value-id={redirect.id}
+                  data-confirm="Delete this redirect?"
+                  class="admin-btn admin-btn-sm admin-btn-ghost"
+                >
+                  Delete
+                </button>
+              </td>
+            </tr>
+          <% end %>
+        </tbody>
+      </table>
+    <% end %>
+    """
+  end
+
+  defp broken_urls_table(assigns) do
+    ~H"""
+    <%= if @broken_urls == [] do %>
+      <p>No broken URLs detected.</p>
+    <% else %>
+      <table class="admin-table">
+        <thead>
+          <tr>
+            <th>Path</th>
+            <th>Prior traffic</th>
+            <th>404s</th>
+            <th>First seen</th>
+            <th>Last seen</th>
+            <th></th>
+          </tr>
+        </thead>
+        <tbody>
+          <%= for broken_url <- @broken_urls do %>
+            <tr>
+              <td><code>{broken_url.path}</code></td>
+              <td>{broken_url.prior_analytics_hits}</td>
+              <td>{broken_url.recent_404_count}</td>
+              <td>{Calendar.strftime(broken_url.first_seen_at, "%d %b %Y")}</td>
+              <td>{Calendar.strftime(broken_url.last_seen_at, "%d %b %Y")}</td>
+              <td class="flex gap-2">
+                <button
+                  phx-click="redirect_broken_url"
+                  phx-value-path={broken_url.path}
+                  class="admin-btn admin-btn-sm admin-btn-primary"
+                >
+                  Redirect
+                </button>
+                <button
+                  phx-click="ignore_broken_url"
+                  phx-value-id={broken_url.id}
+                  class="admin-btn admin-btn-sm admin-btn-ghost"
+                >
+                  Ignore
+                </button>
+              </td>
+            </tr>
+          <% end %>
+        </tbody>
+      </table>
+    <% end %>
+    """
+  end
+
+  defp create_form(assigns) do
+    ~H"""
+    <.form for={@form} phx-submit="create_redirect" style="max-width: 32rem;">
+      <.input
+        field={@form[:from_path]}
+        label="From path"
+        placeholder="/products/old-slug"
+        required
+      />
+      <.input
+        field={@form[:to_path]}
+        label="To path"
+        placeholder="/products/new-slug"
+        required
+      />
+      <.input
+        field={@form[:status_code]}
+        type="select"
+        label="Status code"
+        options={[{"301 (permanent)", "301"}, {"302 (temporary)", "302"}]}
+      />
+      <button type="submit" class="admin-btn admin-btn-primary">Create redirect</button>
+    </.form>
+    """
+  end
+
+  defp tab_button(assigns) do
+    assigns =
+      assigns
+      |> assign(:active, assigns.active == assigns.tab)
+      |> assign_new(:count, fn -> nil end)
+
+    ~H"""
+    <button
+      phx-click="switch_tab"
+      phx-value-tab={@tab}
+      class={[
+        "admin-btn admin-btn-sm",
+        @active && "admin-btn-primary",
+        !@active && "admin-btn-ghost"
+      ]}
+    >
+      {@label}
+      <span :if={@count && @count > 0} class="admin-badge admin-badge-sm ml-1">{@count}</span>
+    </button>
+    """
+  end
+
+  defp resolve_matching_broken_url(from_path) do
+    case Redirects.get_broken_url_by_path(from_path) do
+      nil -> :ok
+      broken_url -> Redirects.mark_broken_url_resolved(broken_url)
+    end
+  end
+
+  defp source_colour("auto_slug_change"), do: "info"
+  defp source_colour("auto_product_deleted"), do: "warning"
+  defp source_colour("analytics_detected"), do: "accent"
+  defp source_colour("admin"), do: "neutral"
+  defp source_colour(_), do: "neutral"
+end

lib/berrypod_web/plugs/broken_url_tracker.ex

@@ -0,0 +1,34 @@
+defmodule BerrypodWeb.Plugs.BrokenUrlTracker do
+  @moduledoc """
+  Wraps the router to record 404s in the broken URLs table.
+
+  Works in dev mode too — Plug.Debugger intercepts exceptions before
+  error templates render, so we catch NoRouteError here, record it,
+  then re-raise so the normal error handling continues.
+  """
+
+  @behaviour Plug
+
+  def init(opts) do
+    router = Keyword.fetch!(opts, :router)
+    router_opts = router.init([])
+    {router, router_opts}
+  end
+
+  def call(conn, {router, router_opts}) do
+    router.call(conn, router_opts)
+  rescue
+    e in Phoenix.Router.NoRouteError ->
+      unless static_path?(conn.request_path) do
+        Berrypod.Redirects.record_broken_url(conn.request_path, 0)
+      end
+
+      reraise e, __STACKTRACE__
+  end
+
+  defp static_path?(path) do
+    String.starts_with?(path, "/assets/") or
+      String.starts_with?(path, "/images/") or
+      String.starts_with?(path, "/favicon")
+  end
+end

lib/berrypod_web/plugs/redirects.ex

@@ -0,0 +1,66 @@
+defmodule BerrypodWeb.Plugs.Redirects do
+  @moduledoc """
+  Plug that handles URL normalisation and custom redirects.
+
+  Three concerns in one pass:
+  1. Trailing slash removal (/products/foo/ → /products/foo)
+  2. Case normalisation for shop paths (/Products/Foo → /products/foo)
+  3. Custom redirect lookup from the redirects table (ETS-cached)
+
+  All redirects preserve query params.
+  """
+
+  import Plug.Conn
+  alias Berrypod.Redirects
+
+  # Only case-normalise paths under these prefixes (SEO-relevant shop routes).
+  # Paths with tokens, API keys, or other case-sensitive segments are excluded.
+  @lowercase_prefixes ~w(/products /collections /about /delivery /privacy /terms /search /cart /contact)
+
+  def init(opts), do: opts
+
+  def call(conn, _opts) do
+    path = conn.request_path
+    stripped = strip_trailing_slash(path)
+
+    cond do
+      # Trailing slash — redirect to canonical form
+      stripped != path ->
+        redirect_to(conn, stripped, 301)
+
+      # Case mismatch on a shop path — redirect to lowercase
+      lowercase_path?(path) and String.downcase(path) != path ->
+        redirect_to(conn, String.downcase(path), 301)
+
+      # Check redirect table (ETS-cached)
+      :else ->
+        case Redirects.lookup(path) do
+          {:ok, redirect} ->
+            Redirects.increment_hit_count(redirect)
+            redirect_to(conn, redirect.to_path, redirect.status_code)
+
+          :not_found ->
+            conn
+        end
+    end
+  end
+
+  defp lowercase_path?(path) do
+    Enum.any?(@lowercase_prefixes, &String.starts_with?(String.downcase(path), &1))
+  end
+
+  defp redirect_to(conn, target, status_code) do
+    location = append_query(target, conn.query_string)
+
+    conn
+    |> put_resp_header("location", location)
+    |> send_resp(status_code, "")
+    |> halt()
+  end
+
+  defp strip_trailing_slash("/"), do: "/"
+  defp strip_trailing_slash(path), do: String.trim_trailing(path, "/")
+
+  defp append_query(path, ""), do: path
+  defp append_query(path, qs), do: "#{path}?#{qs}"
+end

lib/berrypod_web/router.ex

@@ -229,6 +229,7 @@ defmodule BerrypodWeb.Router do
       live "/providers/:id/edit", Admin.Providers.Form, :edit
       live "/settings", Admin.Settings, :index
       live "/settings/email", Admin.EmailSettings, :index
+      live "/redirects", Admin.Redirects, :index
     end
 
     # Theme editor: admin root layout but full-screen (no sidebar)