Persist chat history

docs/architecture.md

@@ -80,6 +80,8 @@ write to it directly; insert/update the `records` table instead.
 | `ScrobbleRules.ScrobbleRule` | `scrobble_rules` | `id` (integer) | type (:album/:artist), match_value, target_musicbrainz_id, enabled |
 | `OnlineStoreTemplates.OnlineStoreTemplate` | `online_store_templates` | `id` | name, url_template, enabled |
 | `Secrets.Secret` | `secrets` | `name` (string) | value (encrypted binary) |
+| `Chats.Chat` | `chats` | `id` (binary_id) | entity (:record/:artist), musicbrainz_id, topic, has_many :messages |
+| `Chats.Message` | `chat_messages` | `id` (binary_id) | role, content, position, belongs_to :chat |
 
 Last.fm schemas (separate, not Ecto-persisted to main DB):
 - `LastFm.Track` — scrobbled tracks stored in Last.fm's own tables via `LastFm.Feed`
@@ -97,6 +99,7 @@ Last.fm schemas (separate, not Ecto-persisted to main DB):
 | `Artists` | ArtistInfo, ArtistRecord | Artist metadata from MusicBrainz/Discogs/Wikipedia/Last.fm, images, search |
 | `Assets` | Asset | Binary asset storage (covers, artist images), cache tracking |
 | `Notes` | Note | Free-text notes for records and artists |
+| `Chats` | Chat, Message | Persistent AI chat conversations for records and artists |
 | `RecordSets` | RecordSet, RecordSetItem | User-curated record groupings with ordering |
 | `ScrobbleRules` | ScrobbleRule | Rules to remap Last.fm scrobble data to correct MusicBrainz IDs; searchable by match_value/target/description, orderable by alphabetical or inserted_at |
 | `ScrobbleActivity` | — | Scrobbling releases/media/tracks to Last.fm |

lib/music_library/chats.ex

@@ -0,0 +1,106 @@
+defmodule MusicLibrary.Chats do
+  @moduledoc """
+  Persistent storage for AI chat conversations about records and artists.
+  """
+
+  import Ecto.Query, warn: false
+
+  alias MusicLibrary.Chats.{Chat, Message}
+  alias MusicLibrary.Repo
+
+  @spec list_chats(atom(), String.t()) :: [Chat.t()]
+  def list_chats(entity, musicbrainz_id) do
+    message_count_query =
+      from(m in Message,
+        where: m.chat_id == parent_as(:chat).id,
+        select: count(m.id)
+      )
+
+    from(c in Chat,
+      as: :chat,
+      where: c.entity == ^entity and c.musicbrainz_id == ^musicbrainz_id,
+      order_by: [desc: c.updated_at],
+      select_merge: %{message_count: subquery(message_count_query)}
+    )
+    |> Repo.all()
+  end
+
+  @spec has_any_chats?(atom(), String.t()) :: boolean()
+  def has_any_chats?(entity, musicbrainz_id) do
+    from(c in Chat,
+      where: c.entity == ^entity and c.musicbrainz_id == ^musicbrainz_id
+    )
+    |> Repo.exists?()
+  end
+
+  @spec get_chat!(String.t()) :: Chat.t()
+  def get_chat!(id) do
+    Chat
+    |> Repo.get!(id)
+    |> Repo.preload(:messages)
+  end
+
+  @spec create_chat_with_message(map(), map()) ::
+          {:ok, Chat.t()} | {:error, Ecto.Changeset.t()}
+  def create_chat_with_message(chat_attrs, message_attrs) do
+    topic =
+      message_attrs
+      |> Map.get(:content, "")
+      |> String.trim()
+      |> String.slice(0, 80)
+
+    Repo.transaction(fn ->
+      chat_attrs = Map.put(chat_attrs, :topic, topic)
+
+      with {:ok, chat} <- %Chat{} |> Chat.changeset(chat_attrs) |> Repo.insert(),
+           message_attrs = Map.merge(message_attrs, %{position: 0}),
+           {:ok, _message} <-
+             %Message{chat_id: chat.id}
+             |> Message.changeset(message_attrs)
+             |> Repo.insert() do
+        Repo.preload(chat, :messages)
+      else
+        {:error, changeset} -> Repo.rollback(changeset)
+      end
+    end)
+  end
+
+  @spec add_message(Chat.t(), map()) :: {:ok, Message.t()} | {:error, Ecto.Changeset.t()}
+  def add_message(%Chat{} = chat, attrs) do
+    next_position =
+      from(m in Message,
+        where: m.chat_id == ^chat.id,
+        select: coalesce(max(m.position), -1)
+      )
+      |> Repo.one!()
+      |> Kernel.+(1)
+
+    attrs = Map.put(attrs, :position, next_position)
+
+    result =
+      %Message{chat_id: chat.id}
+      |> Message.changeset(attrs)
+      |> Repo.insert()
+
+    case result do
+      {:ok, message} ->
+        touch_chat(chat)
+        {:ok, message}
+
+      error ->
+        error
+    end
+  end
+
+  @spec delete_chat(Chat.t()) :: {:ok, Chat.t()} | {:error, Ecto.Changeset.t()}
+  def delete_chat(%Chat{} = chat) do
+    Repo.delete(chat)
+  end
+
+  defp touch_chat(chat) do
+    now = DateTime.truncate(DateTime.utc_now(), :second)
+
+    from(c in Chat, where: c.id == ^chat.id)
+    |> Repo.update_all(set: [updated_at: now])
+  end
+end

lib/music_library/chats/chat.ex

@@ -0,0 +1,31 @@
+defmodule MusicLibrary.Chats.Chat do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  alias MusicLibrary.Chats.Message
+
+  @primary_key {:id, :binary_id, autogenerate: true}
+  @foreign_key_type :binary_id
+  schema "chats" do
+    field :entity, Ecto.Enum, values: [:record, :artist]
+    field :musicbrainz_id, Ecto.UUID
+    field :topic, :string
+
+    field :message_count, :integer, virtual: true, default: 0
+
+    has_many :messages, Message, preload_order: [asc: :position]
+
+    timestamps(type: :utc_datetime)
+  end
+
+  @type t :: %__MODULE__{}
+
+  @spec changeset(t() | Ecto.Changeset.t(), map()) :: Ecto.Changeset.t()
+  def changeset(chat, attrs) do
+    chat
+    |> cast(attrs, [:entity, :musicbrainz_id, :topic])
+    |> validate_required([:entity, :musicbrainz_id])
+    |> validate_length(:topic, max: 200)
+  end
+end

lib/music_library/chats/message.ex

@@ -0,0 +1,29 @@
+defmodule MusicLibrary.Chats.Message do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  alias MusicLibrary.Chats.Chat
+
+  @primary_key {:id, :binary_id, autogenerate: true}
+  @foreign_key_type :binary_id
+  schema "chat_messages" do
+    field :role, :string
+    field :content, :string
+    field :position, :integer
+
+    belongs_to :chat, Chat
+
+    timestamps(type: :utc_datetime)
+  end
+
+  @type t :: %__MODULE__{}
+
+  @spec changeset(t() | Ecto.Changeset.t(), map()) :: Ecto.Changeset.t()
+  def changeset(message, attrs) do
+    message
+    |> cast(attrs, [:role, :content, :position])
+    |> validate_required([:role, :content, :position])
+    |> validate_inclusion(:role, ["user", "assistant"])
+  end
+end

lib/music_library_web/components/chat.ex

@@ -3,6 +3,7 @@ defmodule MusicLibraryWeb.Components.Chat do
 
   require Logger
 
+  alias MusicLibrary.Chats
   alias MusicLibraryWeb.Markdown
 
   def open(id), do: Fluxon.open_dialog(id)
@@ -14,7 +15,11 @@ defmodule MusicLibraryWeb.Components.Chat do
      |> assign(:messages, [])
      |> assign(:current_response, "")
      |> assign(:loading, false)
-     |> assign(:error, nil)}
+     |> assign(:error, nil)
+     |> assign(:view, :active)
+     |> assign(:chat, nil)
+     |> assign(:chats, [])
+     |> assign(:has_history, false)}
   end
 
   @impl true
@@ -25,6 +30,8 @@ defmodule MusicLibraryWeb.Components.Chat do
   def update(%{done: true}, socket) do
     completed_message = %{role: "assistant", content: socket.assigns.current_response}
 
+    save_assistant_message(socket.assigns.chat, completed_message.content)
+
     {:ok,
      socket
      |> update(:messages, &(&1 ++ [completed_message]))
@@ -40,7 +47,16 @@ defmodule MusicLibraryWeb.Components.Chat do
   end
 
   def update(assigns, socket) do
-    {:ok, assign(socket, assigns)}
+    socket = assign(socket, assigns)
+
+    socket =
+      if changed?(socket, :entity) or changed?(socket, :musicbrainz_id) do
+        assign(socket, :has_history, check_chat_history(socket.assigns))
+      else
+        socket
+      end
+
+    {:ok, socket}
   end
 
   @impl true
@@ -52,113 +68,11 @@ defmodule MusicLibraryWeb.Components.Chat do
         placement="right"
         class="w-md sm:min-w-lg lg:min-w-2xl flex flex-col h-full"
       >
-        <div class="flex items-center gap-2 pb-4 border-b border-zinc-200 dark:border-zinc-700">
+        <%= if @view == :list do %>
-          <h2 class="text-lg font-semibold text-zinc-900 dark:text-zinc-100">
+          {render_list_view(assigns)}
-            {gettext("Chat about %{title}", title: @title)}
+        <% else %>
-          </h2>
+          {render_active_view(assigns)}
-          <.button
+        <% end %>
-            :if={@messages != []}
-            size="icon-sm"
-            variant="ghost"
-            phx-click="clear_chat"
-            phx-target={@myself}
-            aria-label={gettext("Clear chat")}
-          >
-            <.icon name="hero-trash" class="icon" />
-          </.button>
-        </div>
-
-        <div
-          id={"#{@id}-messages"}
-          class="flex-1 overflow-y-auto py-4 space-y-4"
-          phx-hook=".ScrollBottom"
-        >
-          <div
-            :if={@messages == [] and @current_response == ""}
-            class="flex flex-col items-center justify-center h-full text-center text-zinc-500 dark:text-zinc-400"
-          >
-            <.icon
-              name="hero-chat-bubble-left-right"
-              class="size-12 mb-4 text-zinc-300 dark:text-zinc-600"
-            />
-            <p class="text-sm font-medium">{@empty_prompt}</p>
-          </div>
-
-          <div
-            :for={message <- @messages}
-            class={[
-              "max-w-[85%] rounded-lg px-4 py-2 text-sm",
-              message_classes(message.role)
-            ]}
-          >
-            <p :if={message.role == "user"} class="whitespace-pre-wrap">{message.content}</p>
-            <div :if={message.role == "assistant"} class="prose prose-sm dark:prose-invert">
-              {raw(Markdown.to_html(message.content))}
-            </div>
-          </div>
-
-          <div
-            :if={@current_response != ""}
-            class="max-w-[85%] rounded-lg px-4 py-2 text-sm bg-zinc-100 dark:bg-zinc-700 text-zinc-900 dark:text-zinc-100"
-          >
-            <div class="prose prose-sm dark:prose-invert">
-              {raw(Markdown.to_html(@current_response))}
-            </div>
-          </div>
-
-          <div
-            :if={@loading and @current_response == ""}
-            class="flex items-center gap-2 text-zinc-500 dark:text-zinc-400"
-          >
-            <.loading class="size-4" />
-            <span class="text-sm">{gettext("Thinking...")}</span>
-          </div>
-
-          <div
-            :if={@error}
-            class="max-w-[85%] rounded-lg px-4 py-2 text-sm bg-red-50 dark:bg-red-900/20 text-red-700 dark:text-red-300"
-          >
-            <p>{@error}</p>
-            <.button
-              size="xs"
-              variant="ghost"
-              color="danger"
-              phx-click="retry"
-              phx-target={@myself}
-              class="mt-2"
-            >
-              {gettext("Retry")}
-            </.button>
-          </div>
-        </div>
-
-        <div class="pt-4 border-t border-zinc-200 dark:border-zinc-700">
-          <form
-            id={"#{@id}-form"}
-            phx-submit="send_message"
-            phx-target={@myself}
-            class="flex gap-2"
-          >
-            <.input
-              name="message"
-              value=""
-              placeholder={@placeholder}
-              class="flex-1"
-              disabled={@loading}
-              autocomplete="off"
-              autofocus
-            />
-            <.button
-              type="submit"
-              variant="solid"
-              size="icon"
-              disabled={@loading}
-              aria-label={gettext("Send message")}
-            >
-              <.icon name="hero-paper-airplane" class="icon" />
-            </.button>
-          </form>
-        </div>
       </.sheet>
       <script :type={Phoenix.LiveView.ColocatedHook} name=".ScrollBottom">
         export default {
@@ -182,18 +96,242 @@ defmodule MusicLibraryWeb.Components.Chat do
     """
   end
 
+  defp render_list_view(assigns) do
+    ~H"""
+    <div class="flex items-center justify-between pb-4 border-b border-zinc-200 dark:border-zinc-700">
+      <h2 class="text-lg font-semibold text-zinc-900 dark:text-zinc-100">
+        {gettext("Chat history")}
+      </h2>
+      <.button size="sm" variant="soft" phx-click="new_chat" phx-target={@myself}>
+        <.icon name="hero-plus" class="icon" data-slot="icon" />
+        {gettext("New chat")}
+      </.button>
+    </div>
+
+    <div class="flex-1 overflow-y-auto py-4">
+      <div
+        :if={@chats == []}
+        class="flex flex-col items-center justify-center h-full text-center text-zinc-500 dark:text-zinc-400"
+      >
+        <.icon
+          name="hero-chat-bubble-left-right"
+          class="size-12 mb-4 text-zinc-300 dark:text-zinc-600"
+        />
+        <p class="text-sm font-medium">{gettext("No previous chats")}</p>
+      </div>
+
+      <div :for={chat <- @chats} class="group relative">
+        <button
+          phx-click="select_chat"
+          phx-value-id={chat.id}
+          phx-target={@myself}
+          class="w-full text-left px-3 py-3 rounded-lg hover:bg-zinc-50 dark:hover:bg-zinc-800 transition-colors"
+        >
+          <p class="text-sm font-medium text-zinc-900 dark:text-zinc-100 truncate">
+            {chat.topic || gettext("Untitled")}
+          </p>
+          <p class="text-xs text-zinc-500 dark:text-zinc-400 mt-1">
+            {ngettext("%{count} message", "%{count} messages", chat.message_count)} · {Calendar.strftime(
+              chat.updated_at,
+              "%b %-d, %Y"
+            )}
+          </p>
+        </button>
+        <.button
+          size="icon-xs"
+          variant="ghost"
+          color="danger"
+          phx-click="delete_chat"
+          phx-value-id={chat.id}
+          phx-target={@myself}
+          aria-label={gettext("Delete chat")}
+          class="absolute top-3 right-2 opacity-0 group-hover:opacity-100 transition-opacity"
+        >
+          <.icon name="hero-trash" class="icon" />
+        </.button>
+      </div>
+    </div>
+    """
+  end
+
+  defp render_active_view(assigns) do
+    ~H"""
+    <div class="flex items-center gap-2 pb-4 border-b border-zinc-200 dark:border-zinc-700">
+      <h2 class="text-lg font-semibold text-zinc-900 dark:text-zinc-100">
+        {gettext("Chat about %{title}", title: @title)}
+      </h2>
+      <.button
+        :if={@has_history}
+        size="icon-sm"
+        variant="ghost"
+        phx-click="show_chat_list"
+        phx-target={@myself}
+        aria-label={gettext("Chat history")}
+      >
+        <.icon name="hero-clock" class="icon" />
+      </.button>
+      <.button
+        :if={@messages != []}
+        size="icon-sm"
+        variant="ghost"
+        phx-click="new_chat"
+        phx-target={@myself}
+        aria-label={gettext("New chat")}
+      >
+        <.icon name="hero-plus" class="icon" />
+      </.button>
+    </div>
+
+    <div
+      id={"#{@id}-messages"}
+      class="flex-1 overflow-y-auto py-4 space-y-4"
+      phx-hook=".ScrollBottom"
+    >
+      <div
+        :if={@messages == [] and @current_response == ""}
+        class="flex flex-col items-center justify-center h-full text-center text-zinc-500 dark:text-zinc-400"
+      >
+        <.icon
+          name="hero-chat-bubble-left-right"
+          class="size-12 mb-4 text-zinc-300 dark:text-zinc-600"
+        />
+        <p class="text-sm font-medium">{@empty_prompt}</p>
+      </div>
+
+      <div
+        :for={message <- @messages}
+        class={[
+          "max-w-[85%] rounded-lg px-4 py-2 text-sm",
+          message_classes(message.role)
+        ]}
+      >
+        <p :if={message.role == "user"} class="whitespace-pre-wrap">{message.content}</p>
+        <div :if={message.role == "assistant"} class="prose prose-sm dark:prose-invert">
+          {raw(Markdown.to_html(message.content))}
+        </div>
+      </div>
+
+      <div
+        :if={@current_response != ""}
+        class="max-w-[85%] rounded-lg px-4 py-2 text-sm bg-zinc-100 dark:bg-zinc-700 text-zinc-900 dark:text-zinc-100"
+      >
+        <div class="prose prose-sm dark:prose-invert">
+          {raw(Markdown.to_html(@current_response))}
+        </div>
+      </div>
+
+      <div
+        :if={@loading and @current_response == ""}
+        class="flex items-center gap-2 text-zinc-500 dark:text-zinc-400"
+      >
+        <.loading class="size-4" />
+        <span class="text-sm">{gettext("Thinking...")}</span>
+      </div>
+
+      <div
+        :if={@error}
+        class="max-w-[85%] rounded-lg px-4 py-2 text-sm bg-red-50 dark:bg-red-900/20 text-red-700 dark:text-red-300"
+      >
+        <p>{@error}</p>
+        <.button
+          size="xs"
+          variant="ghost"
+          color="danger"
+          phx-click="retry"
+          phx-target={@myself}
+          class="mt-2"
+        >
+          {gettext("Retry")}
+        </.button>
+      </div>
+    </div>
+
+    <div class="pt-4 border-t border-zinc-200 dark:border-zinc-700">
+      <form
+        id={"#{@id}-form"}
+        phx-submit="send_message"
+        phx-target={@myself}
+        class="flex gap-2"
+      >
+        <.input
+          name="message"
+          value=""
+          placeholder={@placeholder}
+          class="flex-1"
+          disabled={@loading}
+          autocomplete="off"
+          autofocus
+        />
+        <.button
+          type="submit"
+          variant="solid"
+          size="icon"
+          disabled={@loading}
+          aria-label={gettext("Send message")}
+        >
+          <.icon name="hero-paper-airplane" class="icon" />
+        </.button>
+      </form>
+    </div>
+    """
+  end
+
   @impl true
   def handle_event("send_message", %{"message" => ""}, socket), do: {:noreply, socket}
 
   def handle_event("send_message", %{"message" => text}, socket),
     do: do_send_message(socket, text)
 
-  def handle_event("clear_chat", _params, socket) do
+  def handle_event("new_chat", _params, socket) do
     {:noreply,
      socket
      |> assign(:messages, [])
      |> assign(:current_response, "")
-     |> assign(:error, nil)}
+     |> assign(:error, nil)
+     |> assign(:chat, nil)
+     |> assign(:view, :active)}
+  end
+
+  def handle_event("show_chat_list", _params, socket) do
+    chats = Chats.list_chats(socket.assigns.entity, socket.assigns.musicbrainz_id)
+
+    {:noreply,
+     socket
+     |> assign(:chats, chats)
+     |> assign(:view, :list)}
+  end
+
+  def handle_event("select_chat", %{"id" => id}, socket) do
+    chat = Chats.get_chat!(id)
+    messages = Enum.map(chat.messages, &%{role: &1.role, content: &1.content})
+
+    {:noreply,
+     socket
+     |> assign(:chat, chat)
+     |> assign(:messages, messages)
+     |> assign(:current_response, "")
+     |> assign(:error, nil)
+     |> assign(:view, :active)}
+  end
+
+  def handle_event("delete_chat", %{"id" => id}, socket) do
+    chat = Chats.get_chat!(id)
+    {:ok, _} = Chats.delete_chat(chat)
+
+    chats = Chats.list_chats(socket.assigns.entity, socket.assigns.musicbrainz_id)
+
+    socket =
+      if socket.assigns.chat && socket.assigns.chat.id == id do
+        socket
+        |> assign(:chat, nil)
+        |> assign(:messages, [])
+        |> assign(:current_response, "")
+        |> assign(:error, nil)
+      else
+        socket
+      end
+
+    {:noreply, assign(socket, :chats, chats)}
   end
 
   def handle_event("retry", _params, socket) do
@@ -217,6 +355,8 @@ defmodule MusicLibraryWeb.Components.Chat do
     chat_module = socket.assigns.chat_module
     chat_context = socket.assigns.chat_context
 
+    chat = persist_user_message(socket, user_message)
+
     Task.Supervisor.start_child(MusicLibrary.TaskSupervisor, fn ->
       case chat_module.stream_response(messages, chat_context, fn chunk ->
              Phoenix.LiveView.send_update(parent_pid, __MODULE__,
@@ -243,11 +383,51 @@ defmodule MusicLibraryWeb.Components.Chat do
     {:noreply,
      socket
      |> assign(:messages, messages)
+     |> assign(:chat, chat)
+     |> assign(:has_history, true)
      |> assign(:loading, true)
      |> assign(:current_response, "")
      |> assign(:error, nil)}
   end
 
+  defp persist_user_message(socket, user_message) do
+    case socket.assigns.chat do
+      nil ->
+        {:ok, chat} =
+          Chats.create_chat_with_message(
+            %{entity: socket.assigns.entity, musicbrainz_id: socket.assigns.musicbrainz_id},
+            %{role: user_message.role, content: user_message.content}
+          )
+
+        chat
+
+      chat ->
+        {:ok, _message} =
+          Chats.add_message(chat, %{role: user_message.role, content: user_message.content})
+
+        chat
+    end
+  end
+
+  defp save_assistant_message(nil, _content), do: :ok
+
+  defp save_assistant_message(chat, content) do
+    case Chats.add_message(chat, %{role: "assistant", content: content}) do
+      {:ok, _message} ->
+        :ok
+
+      {:error, reason} ->
+        Logger.warning("Failed to persist assistant message: #{inspect(reason)}")
+    end
+  end
+
+  defp check_chat_history(%{entity: entity, musicbrainz_id: musicbrainz_id})
+       when not is_nil(entity) and not is_nil(musicbrainz_id) do
+    Chats.has_any_chats?(entity, musicbrainz_id)
+  end
+
+  defp check_chat_history(_assigns), do: false
+
   defp message_classes("user") do
     "ml-auto bg-blue-500 dark:bg-blue-600 text-white"
   end

lib/music_library_web/live/artist_live/show.ex

@@ -494,6 +494,8 @@ defmodule MusicLibraryWeb.ArtistLive.Show do
         sheet_id="artist-chat-sheet"
         module={MusicLibraryWeb.Components.Chat}
         title={@artist.name}
+        entity={:artist}
+        musicbrainz_id={@artist.musicbrainz_id}
         chat_module={MusicLibrary.ArtistChat}
         chat_context={{@artist, @artist_info}}
         placeholder={gettext("Ask about this artist...")}

lib/music_library_web/live/collection_live/show.ex

@@ -306,6 +306,8 @@ defmodule MusicLibraryWeb.CollectionLive.Show do
         sheet_id="record-chat-sheet"
         module={MusicLibraryWeb.Components.Chat}
         title={@record.title}
+        entity={:record}
+        musicbrainz_id={@record.musicbrainz_id}
         chat_module={MusicLibrary.RecordChat}
         chat_context={{@record, @embedding_text}}
         placeholder={gettext("Ask about this album...")}

lib/music_library_web/live/wishlist_live/show.ex

@@ -251,6 +251,8 @@ defmodule MusicLibraryWeb.WishlistLive.Show do
         sheet_id="record-chat-sheet"
         module={MusicLibraryWeb.Components.Chat}
         title={@record.title}
+        entity={:record}
+        musicbrainz_id={@record.musicbrainz_id}
         chat_module={MusicLibrary.RecordChat}
         chat_context={{@record, @embedding_text}}
         placeholder={gettext("Ask about this album...")}

priv/gettext/default.pot

@@ -1872,11 +1872,6 @@ msgstr ""
 msgid "Chat about album"
 msgstr ""
 
-#: lib/music_library_web/components/chat.ex
-#, elixir-autogen, elixir-format
-msgid "Clear chat"
-msgstr ""
-
 #: lib/music_library_web/components/chat.ex
 #, elixir-autogen, elixir-format
 msgid "Send message"
@@ -2308,3 +2303,35 @@ msgstr ""
 #, elixir-autogen, elixir-format
 msgid "No online store templates found"
 msgstr ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "%{count} message"
+msgid_plural "%{count} messages"
+msgstr[0] ""
+msgstr[1] ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "Chat history"
+msgstr ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "Delete chat"
+msgstr ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "New chat"
+msgstr ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "No previous chats"
+msgstr ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "Untitled"
+msgstr ""

priv/gettext/en/LC_MESSAGES/default.po

@@ -1872,11 +1872,6 @@ msgstr ""
 msgid "Chat about album"
 msgstr ""
 
-#: lib/music_library_web/components/chat.ex
-#, elixir-autogen, elixir-format
-msgid "Clear chat"
-msgstr ""
-
 #: lib/music_library_web/components/chat.ex
 #, elixir-autogen, elixir-format
 msgid "Send message"
@@ -2308,3 +2303,35 @@ msgstr ""
 #, elixir-autogen, elixir-format
 msgid "No online store templates found"
 msgstr ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "%{count} message"
+msgid_plural "%{count} messages"
+msgstr[0] ""
+msgstr[1] ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "Chat history"
+msgstr ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format, fuzzy
+msgid "Delete chat"
+msgstr ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "New chat"
+msgstr ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "No previous chats"
+msgstr ""
+
+#: lib/music_library_web/components/chat.ex
+#, elixir-autogen, elixir-format
+msgid "Untitled"
+msgstr ""

priv/repo/migrations/20260317130441_create_chats.exs

@@ -0,0 +1,34 @@
+defmodule MusicLibrary.Repo.Migrations.CreateChats do
+  use Ecto.Migration
+
+  def change do
+    create table(:chats, primary_key: false) do
+      add :id, :binary_id, primary_key: true
+      add :entity, :string, null: false
+      add :musicbrainz_id, :uuid, null: false
+      add :topic, :string
+
+      timestamps(type: :utc_datetime)
+    end
+
+    # Listing chats for a specific entity
+    create index(:chats, [:entity, :musicbrainz_id])
+
+    # Ordered listing of chats for a specific entity
+    create index(:chats, [:entity, :musicbrainz_id, :updated_at])
+
+    create table(:chat_messages, primary_key: false) do
+      add :id, :binary_id, primary_key: true
+      add :role, :string, null: false
+      add :content, :text, null: false
+      add :position, :integer, null: false
+
+      add :chat_id, references(:chats, type: :binary_id, on_delete: :delete_all), null: false
+
+      timestamps(type: :utc_datetime)
+    end
+
+    # Ordered listing of messages within a chat
+    create index(:chat_messages, [:chat_id, :position])
+  end
+end

test/music_library/chats_test.exs

@@ -0,0 +1,153 @@
+defmodule MusicLibrary.ChatsTest do
+  use MusicLibrary.DataCase
+
+  alias MusicLibrary.Chats
+  alias MusicLibrary.Chats.Chat
+
+  @musicbrainz_id Ecto.UUID.generate()
+
+  defp create_chat(_context) do
+    {:ok, chat} =
+      Chats.create_chat_with_message(
+        %{entity: :record, musicbrainz_id: @musicbrainz_id},
+        %{role: "user", content: "Tell me about this album"}
+      )
+
+    %{chat: chat}
+  end
+
+  describe "list_chats/2" do
+    setup [:create_chat]
+
+    test "returns empty list when no chats exist" do
+      assert Chats.list_chats(:record, Ecto.UUID.generate()) == []
+    end
+
+    test "returns chats for entity with message count", %{chat: chat} do
+      chats = Chats.list_chats(:record, @musicbrainz_id)
+
+      assert [listed_chat] = chats
+      assert listed_chat.id == chat.id
+      assert listed_chat.message_count == 1
+    end
+
+    test "does not return chats for different entity", %{chat: _chat} do
+      assert Chats.list_chats(:artist, @musicbrainz_id) == []
+    end
+
+    test "orders by updated_at desc", %{chat: first_chat} do
+      {:ok, second_chat} =
+        Chats.create_chat_with_message(
+          %{entity: :record, musicbrainz_id: @musicbrainz_id},
+          %{role: "user", content: "Another question"}
+        )
+
+      chats = Chats.list_chats(:record, @musicbrainz_id)
+      assert [%{id: id1}, %{id: id2}] = chats
+      assert id1 == second_chat.id
+      assert id2 == first_chat.id
+    end
+  end
+
+  describe "get_chat!/1" do
+    setup [:create_chat]
+
+    test "returns chat with preloaded messages", %{chat: chat} do
+      found = Chats.get_chat!(chat.id)
+
+      assert found.id == chat.id
+      assert found.entity == :record
+      assert [message] = found.messages
+      assert message.role == "user"
+      assert message.content == "Tell me about this album"
+    end
+
+    test "raises for nonexistent chat" do
+      assert_raise Ecto.NoResultsError, fn ->
+        Chats.get_chat!(Ecto.UUID.generate())
+      end
+    end
+  end
+
+  describe "create_chat_with_message/2" do
+    test "creates chat with first message" do
+      assert {:ok, chat} =
+               Chats.create_chat_with_message(
+                 %{entity: :artist, musicbrainz_id: @musicbrainz_id},
+                 %{role: "user", content: "Who is this artist?"}
+               )
+
+      assert chat.entity == :artist
+      assert chat.musicbrainz_id == @musicbrainz_id
+      assert chat.topic == "Who is this artist?"
+      assert [message] = chat.messages
+      assert message.role == "user"
+      assert message.position == 0
+    end
+
+    test "truncates topic to 80 characters" do
+      long_message = String.duplicate("a", 200)
+
+      assert {:ok, chat} =
+               Chats.create_chat_with_message(
+                 %{entity: :record, musicbrainz_id: @musicbrainz_id},
+                 %{role: "user", content: long_message}
+               )
+
+      assert String.length(chat.topic) == 80
+    end
+
+    test "returns error for invalid chat attrs" do
+      assert {:error, _changeset} =
+               Chats.create_chat_with_message(
+                 %{},
+                 %{role: "user", content: "Hello"}
+               )
+    end
+  end
+
+  describe "add_message/2" do
+    setup [:create_chat]
+
+    test "adds message with auto-computed position", %{chat: chat} do
+      assert {:ok, message} =
+               Chats.add_message(chat, %{role: "assistant", content: "Here's what I know..."})
+
+      assert message.role == "assistant"
+      assert message.position == 1
+      assert message.chat_id == chat.id
+    end
+
+    test "increments position for each message", %{chat: chat} do
+      {:ok, _} = Chats.add_message(chat, %{role: "assistant", content: "Response 1"})
+      {:ok, msg} = Chats.add_message(chat, %{role: "user", content: "Follow up"})
+
+      assert msg.position == 2
+    end
+
+    test "touches chat updated_at", %{chat: chat} do
+      # Force a different timestamp by manually setting the original earlier
+      Repo.update_all(
+        from(c in Chat, where: c.id == ^chat.id),
+        set: [updated_at: ~U[2025-01-01 00:00:00Z]]
+      )
+
+      {:ok, _} = Chats.add_message(chat, %{role: "assistant", content: "Response"})
+
+      updated_chat = Chats.get_chat!(chat.id)
+      assert DateTime.compare(updated_chat.updated_at, ~U[2025-01-01 00:00:00Z]) == :gt
+    end
+  end
+
+  describe "delete_chat/1" do
+    setup [:create_chat]
+
+    test "deletes chat and its messages", %{chat: chat} do
+      assert {:ok, _} = Chats.delete_chat(chat)
+
+      assert_raise Ecto.NoResultsError, fn ->
+        Chats.get_chat!(chat.id)
+      end
+    end
+  end
+end