add analytics-powered 404 monitoring with FTS5 auto-resolve

BrokenUrlTracker now queries real analytics pageview counts instead of
hardcoding 0, so broken URLs with prior traffic are distinguished from
bot noise. For /products/ 404s with a single FTS5 search match, auto-
creates a redirect and marks the broken URL resolved. 1232 tests.

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

lib/berrypod/analytics.ex

@@ -364,6 +364,20 @@ defmodule Berrypod.Analytics do
     |> Repo.all()
   end
 
+  @doc """
+  Counts all-time pageviews for a specific path.
+
+  Used by the broken URL tracker to distinguish real broken URLs
+  (paths that previously had traffic) from bot noise.
+  """
+  def count_pageviews_for_path(path) do
+    from(e in Event,
+      where: e.name == "pageview" and e.pathname == ^path,
+      select: count()
+    )
+    |> Repo.one()
+  end
+
   @doc """
   Deletes events older than the given datetime. Used by the retention worker.
   """

lib/berrypod/redirects.ex

@@ -336,6 +336,44 @@ defmodule Berrypod.Redirects do
     Repo.one(from b in BrokenUrl, where: b.path == ^path and b.status == "pending")
   end
 
+  # ── Auto-resolve ──
+
+  @doc """
+  Attempts to auto-resolve a broken product URL using FTS5 search.
+
+  Converts the slug back to words and searches the product index.
+  If exactly one result is found, creates a redirect and marks
+  the broken URL as resolved. Multiple or zero results are left
+  for admin review.
+  """
+  def attempt_auto_resolve("/products/" <> old_slug = path) do
+    query = old_slug |> String.replace("-", " ") |> String.trim()
+
+    case Berrypod.Search.search(query) do
+      [%{slug: new_slug}] when new_slug != old_slug ->
+        case create_auto(%{
+               from_path: path,
+               to_path: "/products/#{new_slug}",
+               source: "analytics_auto_resolved"
+             }) do
+          {:ok, _redirect} ->
+            if broken = get_broken_url_by_path(path) do
+              mark_broken_url_resolved(broken)
+            end
+
+            :resolved
+
+          _error ->
+            :no_match
+        end
+
+      _ ->
+        :no_match
+    end
+  end
+
+  def attempt_auto_resolve(_path), do: :no_match
+
   # ── Pruning ──
 
   @doc """

lib/berrypod/redirects/redirect.ex

@@ -5,7 +5,7 @@ defmodule Berrypod.Redirects.Redirect do
   @primary_key {:id, :binary_id, autogenerate: true}
   @foreign_key_type :binary_id
 
-  @sources ~w(auto_slug_change auto_product_deleted analytics_detected admin)
+  @sources ~w(auto_slug_change auto_product_deleted analytics_auto_resolved admin)
 
   schema "redirects" do
     field :from_path, :string

lib/berrypod_web/plugs/broken_url_tracker.ex

@@ -20,7 +20,12 @@ defmodule BerrypodWeb.Plugs.BrokenUrlTracker do
   rescue
     e in Phoenix.Router.NoRouteError ->
       unless static_path?(conn.request_path) do
-        Berrypod.Redirects.record_broken_url(conn.request_path, 0)
+        prior_hits = Berrypod.Analytics.count_pageviews_for_path(conn.request_path)
+        Berrypod.Redirects.record_broken_url(conn.request_path, prior_hits)
+
+        if prior_hits > 0 do
+          Berrypod.Redirects.attempt_auto_resolve(conn.request_path)
+        end
       end
 
       reraise e, __STACKTRACE__

test/berrypod/analytics_test.exs

@@ -366,6 +366,23 @@ defmodule Berrypod.AnalyticsTest do
     end
   end
 
+  describe "count_pageviews_for_path/1" do
+    test "counts all pageviews for a specific path" do
+      v1 = :crypto.strong_rand_bytes(8)
+      v2 = :crypto.strong_rand_bytes(8)
+
+      insert_event(%{visitor_hash: v1, pathname: "/products/classic-tee"})
+      insert_event(%{visitor_hash: v2, pathname: "/products/classic-tee"})
+      insert_event(%{visitor_hash: v1, pathname: "/products/other"})
+
+      assert Analytics.count_pageviews_for_path("/products/classic-tee") == 2
+    end
+
+    test "returns 0 for paths with no history" do
+      assert Analytics.count_pageviews_for_path("/products/never-visited") == 0
+    end
+  end
+
   describe "delete_events_before/1" do
     test "deletes old events" do
       old = DateTime.add(DateTime.utc_now(), -400, :day) |> DateTime.truncate(:second)

test/berrypod/redirects_integration_test.exs

@@ -1,7 +1,8 @@
 defmodule Berrypod.RedirectsIntegrationTest do
-  use Berrypod.DataCase, async: true
+  # async: false because FTS5 search index is shared state
+  use Berrypod.DataCase, async: false
 
-  alias Berrypod.{Products, Redirects}
+  alias Berrypod.{Products, Redirects, Search}
   import Berrypod.ProductsFixtures
 
   setup do
@@ -88,4 +89,45 @@ defmodule Berrypod.RedirectsIntegrationTest do
                Redirects.lookup("/products/#{product.slug}")
     end
   end
+
+  describe "attempt_auto_resolve/1" do
+    test "creates redirect when FTS5 finds a single match" do
+      # Product was renamed: "Classic Tee" -> "Classic Tee V2"
+      # Old slug was "classic-tee", new slug is "classic-tee-v2"
+      product =
+        product_fixture(%{
+          title: "Classic Tee V2",
+          slug: "classic-tee-v2",
+          category: "T-Shirts",
+          visible: true,
+          status: "active"
+        })
+
+      product_variant_fixture(%{product: product, title: "Medium / Black", price: 2500})
+      Search.rebuild_index()
+
+      # Record a broken URL for the old slug
+      {:ok, _} = Redirects.record_broken_url("/products/classic-tee", 10)
+
+      assert :resolved = Redirects.attempt_auto_resolve("/products/classic-tee")
+
+      # Redirect should point to the matched product
+      assert {:ok, %{to_path: "/products/classic-tee-v2"}} =
+               Redirects.lookup("/products/classic-tee")
+
+      # Broken URL should be marked resolved
+      assert Redirects.list_broken_urls("pending") == []
+    end
+
+    test "returns :no_match when no search results" do
+      Search.rebuild_index()
+
+      assert :no_match = Redirects.attempt_auto_resolve("/products/totally-unique-nonexistent")
+    end
+
+    test "returns :no_match for non-product paths" do
+      assert :no_match = Redirects.attempt_auto_resolve("/about")
+      assert :no_match = Redirects.attempt_auto_resolve("/collections/old-category")
+    end
+  end
 end