diff --git a/GEMINI.md b/GEMINI.md
index ff48f8f..11b77c6 100644
--- a/GEMINI.md
+++ b/GEMINI.md
@@ -53,18 +53,26 @@ This is a non-negotiable security requirement.
 - **Close Issues in Commits:** Use `Closes #<issue_number>` in commit messages.
 - **Commit with Confidence:** Before amending a commit, run `git log -n 1` to ensure you are modifying the correct one. Prefer using `fixup!` commits for targeted changes to avoid interactive rebasing.
 - **Escape Backticks:** When using `git commit -m`, escape backticks (`).
+- **Atomic Commits:** Each commit should represent a single logical change. Do not group unrelated changes.
+- **Descriptive Messages:** Commit messages should be descriptive and explain the "what" and "why" of the change.
+- **Pull Before Pushing:** Always run `git pull --rebase` before pushing to ensure your local branch is up to date.
 - **Check Status Before Stashing:** Run `git status` before `git stash` to be aware of untracked files.
 
 ### Elixir & Phoenix Conventions
 - **Navigate with Precision:** Use `get_source_location` to find module/function definitions.
 - **Data Integrity:** All validation must be in Ecto changesets. Keep `priv/repo/seeds.exs` updated.
 - **Real-time Updates:** Broadcast only resource IDs via PubSub, not full data objects.
+- **Migrations:** Prefer Ecto's migration helpers over raw SQL for schema changes.
 - **UI & Components:**
     - All user-facing text must be in Portuguese (`pt_PT`) using `gettext`.
     - Use `Phoenix.VerifiedRoutes` in components that use the `~p` sigil.
     - Verify `attr` definitions in `core_components.ex` before using them.
     - Wrap all top-level LiveViews in the `<.main_layout>` component.
 
+### Tool Usage
+- **Use Existing Tools:** Before attempting to use a tool, ensure it exists in the provided list. Do not hallucinate tool names.
+- **Prefer Framework Features:** When available, prefer using framework-specific features (e.g., Ecto migrations) over raw SQL or other low-level implementations.
+
 ---
 
 ## 
@@ -72,10 +80,11 @@ This is a non-negotiable security requirement.
 
 - **ALWAYS Test, Then Format:** Run `mix test` after any change. If it passes, run `mix format`.
 - **Write Feature Tests:** New features require new tests.
+- **Treat Warnings as Errors:** Address all compiler warnings before committing.
 - **The Two-Strike Rule:** If a second attempt to fix a test fails, stop and re-evaluate the approach.
 - **Verify the Outcome:** Prioritize testing the business outcome over UI details.
-- **Fixtures First:** Use existing fixtures from `test/support/fixtures/` for test data.
+- **Fixtures First:** Use existing fixtures from `test/support/fixtures/` for test data. Note that fixture files use the `.ex` extension.
 - **Debug the App, Not the Test:** Analyze the stack trace to find the root cause in the application code.
 - **Testing LiveView Navigation:** Use the `follow_redirect(conn)` helper to test `push_navigate` or `push_redirect`.
 - **Testing Stateless Components:** Use `render_component/2` for stateless functional components.
-- **Testing with Scope:** Use the `log_in_user/2` helper in tests to set up the `current_scope`.
\ No newline at end of file
+- **Testing with Scope:** Use the `log_in_user/2` helper in tests to set up the `current_scope`.
diff --git a/lib/cms/accounts.ex b/lib/cms/accounts.ex
index 9f88ae0..c12c355 100644
--- a/lib/cms/accounts.ex
+++ b/lib/cms/accounts.ex
@@ -13,7 +13,8 @@ defmodule CMS.Accounts do
   def list_groups(%Scope{organization: %Organization{id: org_id}}) do
     from(g in Group,
       where: g.organization_id == ^org_id,
-      order_by: [asc: g.name]
+      order_by: [asc: g.name],
+      preload: [:users]
     )
     |> Repo.all()
   end
@@ -28,6 +29,12 @@ defmodule CMS.Accounts do
     Group.changeset(group, attrs, scope)
   end
 
+  def update_group(scope, group, attrs) do
+    group
+    |> Group.changeset(attrs, scope)
+    |> Repo.update()
+  end
+
   ## Database getters
 
   @doc """
@@ -297,8 +304,12 @@ defmodule CMS.Accounts do
     {:ok, query} = UserToken.verify_session_token_query(token)
 
     case Repo.one(query) do
-      {user, token_inserted_at} -> {Repo.preload(user, :organization), token_inserted_at}
-      _ -> nil
+      {user, token_inserted_at} ->
+        user = Repo.preload(user, [:organization, :groups])
+        {user, token_inserted_at}
+
+      _ ->
+        nil
     end
   end
 
diff --git a/lib/cms/accounts/group.ex b/lib/cms/accounts/group.ex
index a21d820..43a8a3a 100644
--- a/lib/cms/accounts/group.ex
+++ b/lib/cms/accounts/group.ex
@@ -9,6 +9,9 @@ defmodule CMS.Accounts.Group do
     field :description, :string
 
     belongs_to :organization, CMS.Accounts.Organization
+
+    many_to_many :users, CMS.Accounts.User, join_through: "groups_users"
+
     timestamps()
   end
 
diff --git a/lib/cms/accounts/scope.ex b/lib/cms/accounts/scope.ex
index ef136f4..06778fd 100644
--- a/lib/cms/accounts/scope.ex
+++ b/lib/cms/accounts/scope.ex
@@ -18,7 +18,7 @@ defmodule CMS.Accounts.Scope do
 
   alias CMS.Accounts.{User, Organization}
 
-  defstruct user: nil, organization: nil
+  defstruct user: nil, organization: nil, groups: []
 
   @doc """
   Creates a scope for the given user.
@@ -26,9 +26,9 @@ defmodule CMS.Accounts.Scope do
   Expects the user struct to have the `:organization` association preloaded.
   Returns nil if no user is given.
   """
-  def for_user(%User{} = user, %Organization{} = organization) do
+  def for_user(%User{} = user, %Organization{} = organization, groups \\ []) do
     true = user.organization_id == organization.id
 
-    %__MODULE__{user: user, organization: organization}
+    %__MODULE__{user: user, organization: organization, groups: groups}
   end
 end
diff --git a/lib/cms/accounts/user.ex b/lib/cms/accounts/user.ex
index 21a10cc..f437212 100644
--- a/lib/cms/accounts/user.ex
+++ b/lib/cms/accounts/user.ex
@@ -22,6 +22,8 @@ defmodule CMS.Accounts.User do
 
     has_many :prayer_requests, CMS.Prayers.PrayerRequest
 
+    many_to_many :groups, CMS.Accounts.Group, join_through: "groups_users"
+
     field :role, Ecto.Enum, values: @roles
 
     timestamps(type: :utc_datetime)
diff --git a/lib/cms/prayers.ex b/lib/cms/prayers.ex
index bff8aa0..2d61b29 100644
--- a/lib/cms/prayers.ex
+++ b/lib/cms/prayers.ex
@@ -4,6 +4,7 @@ defmodule CMS.Prayers do
   """
 
   import Ecto.Query, warn: false
+
   alias CMS.Repo
 
   alias CMS.Accounts.Scope
@@ -19,11 +20,16 @@ defmodule CMS.Prayers do
 
   """
   def list_prayer_requests(%Scope{} = scope) do
+    user_group_ids = Enum.map(scope.groups, & &1.id)
+
     from(p in PrayerRequest,
-      where: p.organization_id == ^scope.organization.id,
+      where:
+        p.organization_id == ^scope.organization.id and
+          ((p.visibility == :private and p.user_id == ^scope.user.id) or
+             p.visibility == :organization or
+             (p.visibility == :group and p.group_id in ^user_group_ids)),
       order_by: [desc: p.inserted_at],
-      # Preload `created_by` to display the name of the user who created the prayer request.
-      preload: [:organization, :user, :created_by]
+      preload: [:organization, :user]
     )
     |> Repo.all()
   end
@@ -50,8 +56,8 @@ defmodule CMS.Prayers do
   @doc """
   Returns an `%Ecto.Changeset{}` for tracking prayer_request changes.
   """
-  def change_prayer_request(%PrayerRequest{} = prayer_request, attrs \\ %{}) do
-    PrayerRequest.changeset(prayer_request, attrs)
+  def change_prayer_request(%Scope{} = scope, %PrayerRequest{} = prayer_request, attrs \\ %{}) do
+    PrayerRequest.changeset(prayer_request, attrs, scope)
   end
 
   @doc """
@@ -69,19 +75,6 @@ defmodule CMS.Prayers do
   def create_prayer_request(%Scope{} = scope, attrs) do
     %PrayerRequest{}
     |> PrayerRequest.changeset(attrs, scope)
-    |> ensure_user_in_organization(scope)
     |> Repo.insert()
   end
-
-  defp ensure_user_in_organization(changeset, %Scope{} = scope) do
-    if user_id = Ecto.Changeset.get_field(changeset, :user_id) do
-      user = CMS.Accounts.get_user(scope, user_id)
-
-      if is_nil(user) || user.organization_id != scope.organization.id do
-        raise "user #{user_id} is not in organization #{scope.organization.id}"
-      end
-    end
-
-    changeset
-  end
 end
diff --git a/lib/cms/prayers/prayer_request.ex b/lib/cms/prayers/prayer_request.ex
index 34b8008..bc8efb6 100644
--- a/lib/cms/prayers/prayer_request.ex
+++ b/lib/cms/prayers/prayer_request.ex
@@ -6,40 +6,36 @@ defmodule CMS.Prayers.PrayerRequest do
 
   schema "prayer_requests" do
     field :body, :string
+    field :visibility, Ecto.Enum, values: [:private, :organization, :group], default: :private
     # The user's name is used by the autocomplete component's text input.
     field :user_name, :string, virtual: true
     belongs_to :user, CMS.Accounts.User
     belongs_to :organization, CMS.Accounts.Organization
-    belongs_to :created_by, CMS.Accounts.User, foreign_key: :created_by_id
+    belongs_to :group, CMS.Accounts.Group
 
     timestamps()
   end
 
-  @doc false
-  def changeset(prayer_request, attrs) do
-    prayer_request
-    |> cast(attrs, [:body, :user_id])
-    |> validate_required([:body])
-  end
-
   def changeset(prayer_request, attrs, %Scope{} = scope) do
     prayer_request
-    |> changeset(attrs)
-    |> put_assoc(:created_by, scope.user)
+    |> cast(attrs, [:body, :visibility, :group_id])
+    |> validate_required([:body, :visibility])
+    |> put_assoc(:user, scope.user)
     |> put_assoc(:organization, scope.organization)
-    |> assign_user_if_not_present(scope.user)
-    |> validate_required([:user_id])
+    |> validate_group(scope)
   end
 
-  defp assign_user_if_not_present(changeset, user) do
-    if get_field(changeset, :user_id) do
-      changeset
-    else
-      changeset
-      # `put_assoc` is used here because we are associating an existing user,
-      # not creating or updating one.
-      |> put_assoc(:user, user)
-      |> put_change(:user_id, user.id)
+  defp validate_group(changeset, scope) do
+    case get_field(changeset, :visibility) do
+      :group ->
+        if group_id = get_field(changeset, :group_id) do
+          true = group_id in Enum.map(scope.groups, & &1.id)
+        end
+
+        validate_required(changeset, :group_id)
+
+      _ ->
+        changeset
     end
   end
 end
diff --git a/lib/cms_web/live/prayer_live/index.ex b/lib/cms_web/live/prayer_live/index.ex
index 51be857..b8d60fd 100644
--- a/lib/cms_web/live/prayer_live/index.ex
+++ b/lib/cms_web/live/prayer_live/index.ex
@@ -5,10 +5,13 @@ defmodule CMSWeb.PrayerLive.Index do
 
   @impl true
   def mount(_params, _session, socket) do
+    scope = socket.assigns.current_scope
+
     {:ok,
      socket
+     |> assign(:current_scope, scope)
      |> assign(:page_title, "Pedidos de oração")
-     |> assign(:prayer_requests, Prayers.list_prayer_requests(socket.assigns.current_scope))}
+     |> assign(:prayer_requests, Prayers.list_prayer_requests(scope))}
   end
 
   @impl true
diff --git a/lib/cms_web/live/prayer_request_live/form.ex b/lib/cms_web/live/prayer_request_live/form.ex
index c4a1d99..a36e280 100644
--- a/lib/cms_web/live/prayer_request_live/form.ex
+++ b/lib/cms_web/live/prayer_request_live/form.ex
@@ -1,7 +1,6 @@
 defmodule CMSWeb.PrayerRequestLive.Form do
   use CMSWeb, :live_view
 
-  alias CMS.Accounts
   alias CMS.Prayers
   alias CMS.Prayers.PrayerRequest
 
@@ -9,26 +8,16 @@ defmodule CMSWeb.PrayerRequestLive.Form do
   def mount(params, _session, socket) do
     {:ok,
      socket
-     |> assign_users()
+     |> assign(:groups, socket.assigns.current_scope.groups)
      |> apply_action(socket.assigns.live_action, params)}
   end
 
-  defp assign_users(socket) do
-    scope = socket.assigns.current_scope
-    users = if scope.user.role == :admin, do: Accounts.list_users(scope), else: []
-    assign(socket, :users, users)
-  end
-
   defp apply_action(socket, :new, _params) do
-    changeset =
-      %PrayerRequest{}
-      |> Prayers.change_prayer_request()
-      # Initialize the form fields for the autocomplete component.
-      # The `:user_name` is the visible text field, and `:user_id` is the hidden value field.
-      |> Ecto.Changeset.put_change(:user_name, nil)
-      |> Ecto.Changeset.put_change(:user_id, nil)
+    prayer_request = %PrayerRequest{}
+    changeset = Prayers.change_prayer_request(socket.assigns.current_scope, prayer_request)
 
     socket
+    |> assign(:prayer_request, prayer_request)
     |> assign(:form, to_form(changeset))
     |> assign(:page_title, "Novo Pedido de Oração")
   end
@@ -37,27 +26,30 @@ defmodule CMSWeb.PrayerRequestLive.Form do
   def render(assigns) do
     ~H"""
     <.main_layout flash={@flash} current_scope={@current_scope} page_title={@page_title}>
-      <.header>
-        {@page_title}
-        <:subtitle>
-          Escreva o seu pedido de oração abaixo.
-        </:subtitle>
-      </.header>
+      <.form for={@form} id="prayer-request-form" phx-change="validate" phx-submit="save">
+        <.input field={@form[:body]} type="textarea" label="Pedido de Oração" required />
+        <.input
+          field={@form[:visibility]}
+          type="select"
+          label="Visibilidade"
+          options={[
+            {"Privado", "private"},
+            {"Organização", "organization"},
+            {"Grupo", "group"}
+          ]}
+          required
+        />
 
-      <.form for={@form} id="prayer-request-form" phx-submit="save">
-        <div :if={@current_scope.user.role == :admin}>
-          <.autocomplete
-            id="user-id-autocomplete"
-            label="Membro"
-            text_field={@form[:user_name]}
-            value_field={@form[:user_id]}
-            suggestions={@users}
-            suggestion_label={:name}
+        <div :if={@form[:visibility].value == :group}>
+          <.input
+            field={@form[:group_id]}
+            type="select"
+            label="Grupo"
+            options={Enum.map(@groups, &{&1.name, &1.id})}
+            required
           />
         </div>
 
-        <.input field={@form[:body]} type="textarea" label="Pedido de Oração" required />
-
         <footer>
           <.button phx-disable-with="A guardar..." variant="primary">Guardar</.button>
           <.button navigate={~p"/prayers"}>Cancelar</.button>
@@ -67,6 +59,18 @@ defmodule CMSWeb.PrayerRequestLive.Form do
     """
   end
 
+  @impl true
+  def handle_event("validate", %{"prayer_request" => prayer_request_params}, socket) do
+    changeset =
+      Prayers.change_prayer_request(
+        socket.assigns.current_scope,
+        socket.assigns.prayer_request,
+        prayer_request_params
+      )
+
+    {:noreply, assign(socket, form: to_form(changeset, action: :validate))}
+  end
+
   @impl true
   def handle_event("save", %{"prayer_request" => prayer_request_params}, socket) do
     case Prayers.create_prayer_request(socket.assigns.current_scope, prayer_request_params) do
diff --git a/lib/cms_web/user_auth.ex b/lib/cms_web/user_auth.ex
index b86b757..a330769 100644
--- a/lib/cms_web/user_auth.ex
+++ b/lib/cms_web/user_auth.ex
@@ -70,7 +70,7 @@ defmodule CMSWeb.UserAuth do
     with {token, conn} <- ensure_user_token(conn),
          {user, token_inserted_at} <- Accounts.get_user_by_session_token(token) do
       conn
-      |> assign(:current_scope, Scope.for_user(user, organization))
+      |> assign(:current_scope, Scope.for_user(user, user.organization, user.groups))
       |> maybe_reissue_user_session_token(user, token_inserted_at)
     else
       nil ->
@@ -274,7 +274,7 @@ defmodule CMSWeb.UserAuth do
       if user_token = session["user_token"] do
         case Accounts.get_user_by_session_token(user_token) do
           {user, _} ->
-            Scope.for_user(user, organization)
+            Scope.for_user(user, user.organization, user.groups)
 
           # If there is a user token but no user, treat the user as a guest
           _ ->
diff --git a/priv/repo/migrations/20250730135518_add_visibility_to_prayer_requests.exs b/priv/repo/migrations/20250730135518_add_visibility_to_prayer_requests.exs
new file mode 100644
index 0000000..7be7321
--- /dev/null
+++ b/priv/repo/migrations/20250730135518_add_visibility_to_prayer_requests.exs
@@ -0,0 +1,10 @@
+defmodule CMS.Repo.Migrations.AddVisibilityToPrayerRequests do
+  use Ecto.Migration
+
+  def change do
+    alter table(:prayer_requests) do
+      add :visibility, :string, null: false, default: "private"
+      add :group_id, references(:groups, on_delete: :restrict)
+    end
+  end
+end
diff --git a/priv/repo/migrations/20250730141855_create_groups_users_join_table.exs b/priv/repo/migrations/20250730141855_create_groups_users_join_table.exs
new file mode 100644
index 0000000..3ecf329
--- /dev/null
+++ b/priv/repo/migrations/20250730141855_create_groups_users_join_table.exs
@@ -0,0 +1,12 @@
+defmodule CMS.Repo.Migrations.CreateGroupsUsersJoinTable do
+  use Ecto.Migration
+
+  def change do
+    create table(:groups_users, primary_key: false) do
+      add :group_id, references(:groups, on_delete: :delete_all)
+      add :user_id, references(:users, on_delete: :delete_all)
+    end
+
+    create index(:groups_users, [:group_id, :user_id], unique: true)
+  end
+end
diff --git a/priv/repo/migrations/20250802102134_remove_created_by_from_prayer_requests.exs b/priv/repo/migrations/20250802102134_remove_created_by_from_prayer_requests.exs
new file mode 100644
index 0000000..9521356
--- /dev/null
+++ b/priv/repo/migrations/20250802102134_remove_created_by_from_prayer_requests.exs
@@ -0,0 +1,9 @@
+defmodule CMS.Repo.Migrations.RemoveCreatedByFromPrayerRequests do
+  use Ecto.Migration
+
+  def change do
+    alter table(:prayer_requests) do
+      remove :created_by_id
+    end
+  end
+end
diff --git a/priv/repo/seeds.exs b/priv/repo/seeds.exs
index 93611aa..9e3a4e9 100644
--- a/priv/repo/seeds.exs
+++ b/priv/repo/seeds.exs
@@ -26,19 +26,21 @@ org =
       hostname: "localhost"
     })
 
-Repo.get_by(Group, name: "Elders", organization_id: org.id) ||
-  Repo.insert!(%Group{
-    name: "Elders",
-    description: "The elders of the church.",
-    organization_id: org.id
-  })
+elders_group =
+  Repo.get_by(Group, name: "Elders", organization_id: org.id) ||
+    Repo.insert!(%Group{
+      name: "Elders",
+      description: "The elders of the church.",
+      organization_id: org.id
+    })
 
-Repo.get_by(Group, name: "Deacons", organization_id: org.id) ||
-  Repo.insert!(%Group{
-    name: "Deacons",
-    description: "The deacons of the church.",
-    organization_id: org.id
-  })
+deacons_group =
+  Repo.get_by(Group, name: "Deacons", organization_id: org.id) ||
+    Repo.insert!(%Group{
+      name: "Deacons",
+      description: "The deacons of the church.",
+      organization_id: org.id
+    })
 
 family =
   Repo.get_by(Family, designation: "Administrator", organization_id: org.id) ||
@@ -55,6 +57,12 @@ admin_user =
       organization_id: org.id
     })
 
+elders_group = Repo.preload(elders_group, :users)
+
+Ecto.Changeset.change(elders_group, %{})
+|> Ecto.Changeset.put_assoc(:users, [admin_user])
+|> Repo.update!()
+
 smith_family =
   Repo.get_by(Family, designation: "The Smiths", organization_id: org.id) ||
     Repo.insert!(%Family{designation: "The Smiths", organization: org})
@@ -70,6 +78,12 @@ smith_user =
       organization_id: org.id
     })
 
+deacons_group = Repo.preload(deacons_group, :users)
+
+Ecto.Changeset.change(deacons_group, %{})
+|> Ecto.Changeset.put_assoc(:users, [smith_user])
+|> Repo.update!()
+
 jones_family =
   Repo.get_by(Family, designation: "The Joneses", organization_id: org.id) ||
     Repo.insert!(%Family{designation: "The Joneses", organization: org})
@@ -115,7 +129,6 @@ Repo.get_by(PrayerRequest, user_id: smith_user.id) ||
   Repo.insert!(%PrayerRequest{
     body: "Please pray for my upcoming job interview.",
     user_id: smith_user.id,
-    created_by_id: smith_user.id,
     organization_id: org.id
   })
 
@@ -123,7 +136,6 @@ Repo.get_by(PrayerRequest, user_id: jones_user.id) ||
   Repo.insert!(%PrayerRequest{
     body: "Please pray for my grandmother's health.",
     user_id: jones_user.id,
-    created_by_id: jones_user.id,
     organization_id: org.id
   })
 
diff --git a/priv/repo/structure.sql b/priv/repo/structure.sql
index 8fb45da..2130cc0 100644
--- a/priv/repo/structure.sql
+++ b/priv/repo/structure.sql
@@ -197,6 +197,16 @@ CREATE SEQUENCE public.groups_id_seq
 ALTER SEQUENCE public.groups_id_seq OWNED BY public.groups.id;
 
 
+--
+-- Name: groups_users; Type: TABLE; Schema: public; Owner: -
+--
+
+CREATE TABLE public.groups_users (
+    group_id bigint,
+    user_id bigint
+);
+
+
 --
 -- Name: liturgies; Type: TABLE; Schema: public; Owner: -
 --
@@ -291,7 +301,8 @@ CREATE TABLE public.prayer_requests (
     organization_id bigint NOT NULL,
     inserted_at timestamp(0) without time zone NOT NULL,
     updated_at timestamp(0) without time zone NOT NULL,
-    created_by_id bigint NOT NULL
+    visibility character varying(255) DEFAULT 'private'::character varying NOT NULL,
+    group_id bigint
 );
 
 
@@ -575,6 +586,13 @@ CREATE UNIQUE INDEX families_organization_id_designation_index ON public.familie
 CREATE INDEX groups_organization_id_index ON public.groups USING btree (organization_id);
 
 
+--
+-- Name: groups_users_group_id_user_id_index; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE UNIQUE INDEX groups_users_group_id_user_id_index ON public.groups_users USING btree (group_id, user_id);
+
+
 --
 -- Name: liturgies_organization_id_index; Type: INDEX; Schema: public; Owner: -
 --
@@ -684,6 +702,22 @@ ALTER TABLE ONLY public.groups
     ADD CONSTRAINT groups_organization_id_fkey FOREIGN KEY (organization_id) REFERENCES public.organizations(id) ON DELETE CASCADE;
 
 
+--
+-- Name: groups_users groups_users_group_id_fkey; Type: FK CONSTRAINT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.groups_users
+    ADD CONSTRAINT groups_users_group_id_fkey FOREIGN KEY (group_id) REFERENCES public.groups(id) ON DELETE CASCADE;
+
+
+--
+-- Name: groups_users groups_users_user_id_fkey; Type: FK CONSTRAINT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.groups_users
+    ADD CONSTRAINT groups_users_user_id_fkey FOREIGN KEY (user_id) REFERENCES public.users(id) ON DELETE CASCADE;
+
+
 --
 -- Name: blocks liturgies_blocks_block_id_fkey; Type: FK CONSTRAINT; Schema: public; Owner: -
 --
@@ -717,11 +751,11 @@ ALTER TABLE ONLY public.liturgies
 
 
 --
--- Name: prayer_requests prayer_requests_created_by_id_fkey; Type: FK CONSTRAINT; Schema: public; Owner: -
+-- Name: prayer_requests prayer_requests_group_id_fkey; Type: FK CONSTRAINT; Schema: public; Owner: -
 --
 
 ALTER TABLE ONLY public.prayer_requests
-    ADD CONSTRAINT prayer_requests_created_by_id_fkey FOREIGN KEY (created_by_id) REFERENCES public.users(id);
+    ADD CONSTRAINT prayer_requests_group_id_fkey FOREIGN KEY (group_id) REFERENCES public.groups(id) ON DELETE SET NULL;
 
 
 --
@@ -805,3 +839,6 @@ INSERT INTO public."schema_migrations" (version) VALUES (20250719142506);
 INSERT INTO public."schema_migrations" (version) VALUES (20250719145605);
 INSERT INTO public."schema_migrations" (version) VALUES (20250721090414);
 INSERT INTO public."schema_migrations" (version) VALUES (20250721203328);
+INSERT INTO public."schema_migrations" (version) VALUES (20250730135518);
+INSERT INTO public."schema_migrations" (version) VALUES (20250730141855);
+INSERT INTO public."schema_migrations" (version) VALUES (20250802102134);
diff --git a/prompts/workflow_issue_decomposition.md b/prompts/workflow_issue_decomposition.md
index 1a41b36..00bfc8f 100644
--- a/prompts/workflow_issue_decomposition.md
+++ b/prompts/workflow_issue_decomposition.md
@@ -18,10 +18,9 @@ Your task is to act as an expert senior developer and guide me through a collabo
     *   Consult `GEMINI.md`, `README.md`, and any documents in `docs/` to understand the project's architecture, conventions, and required commands.
 
 3.  **Decomposition and Creation:**
-    *   Plan a logical sequence of steps that deliver value incrementally. Focus on creating "vertical slices" of functionality. For example, when creating a new form, a good sequence is: 1. Build the basic UI. 2. Implement the logic to save the data to the database. 3. Add validations and display user feedback.
-    *   Each sub-issue must represent a distinct, verifiable step in this sequence.
+    *   **The Golden Rule of Vertical Slicing:** Each sub-issue **must** deliver a complete, end-to-end piece of user-visible functionality, no matter how small. It must touch every layer of the stack required to make that piece of functionality work (from UI to database).
+    *   **Anti-Pattern Warning:** Crucially, **avoid horizontal slicing** (i.e., by technical layer). Do not create separate sub-issues for "do the database work," "do the UI work," and "do the business logic." This is an anti-pattern because no single sub-issue delivers verifiable user value on its own.
     *   For each step, you will first **create a new issue** using the template in `docs/sub_issue_template.md`. Immediately after the issue is created, you will **link it as a sub-issue** to the parent.
-
     *   **Example of Incorrect vs. Correct Slicing:**
         *   **Incorrect (Horizontal Slicing):**
             1.  Sub-issue: Add `visibility` column to `prayer_requests` table.
diff --git a/test/cms/prayers/prayer_request_test.exs b/test/cms/prayers/prayer_request_test.exs
new file mode 100644
index 0000000..4197750
--- /dev/null
+++ b/test/cms/prayers/prayer_request_test.exs
@@ -0,0 +1,47 @@
+defmodule CMS.Prayers.PrayerRequestTest do
+  use CMS.DataCase
+
+  alias CMS.Prayers.PrayerRequest
+  import CMS.AccountsFixtures
+  import CMS.PrayersFixtures
+
+  setup do
+    org = organization_fixture()
+    user = user_fixture(%{}, org)
+    group = group_fixture(%{users: [user]}, org)
+    scope = user_scope_fixture(user)
+
+    prayer_request =
+      prayer_request_fixture(
+        user: user,
+        created_by: user,
+        organization: org,
+        group: group,
+        visibility: :group
+      )
+
+    {:ok, %{user: user, scope: scope, org: org, prayer_request: prayer_request}}
+  end
+
+  test "changeset sets group_id to nil when visibility changes from :group to :private", %{
+    prayer_request: prayer_request,
+    scope: scope
+  } do
+    changeset = PrayerRequest.changeset(prayer_request, %{visibility: :private}, scope)
+
+    assert changeset.valid?
+    assert get_change(changeset, :visibility) == :private
+    assert get_change(changeset, :group_id) == nil
+  end
+
+  test "changeset sets group_id to nil when visibility changes from :group to :organization", %{
+    prayer_request: prayer_request,
+    scope: scope
+  } do
+    changeset = PrayerRequest.changeset(prayer_request, %{visibility: :organization}, scope)
+
+    assert changeset.valid?
+    assert get_change(changeset, :visibility) == :organization
+    assert get_change(changeset, :group_id) == nil
+  end
+end
diff --git a/test/cms/prayers_test.exs b/test/cms/prayers_test.exs
index 1218bf1..cc90096 100644
--- a/test/cms/prayers_test.exs
+++ b/test/cms/prayers_test.exs
@@ -5,6 +5,7 @@ defmodule CMS.PrayersTest do
 
   describe "prayer_requests" do
     alias CMS.Prayers.PrayerRequest
+    alias CMS.Accounts.User
 
     import CMS.AccountsFixtures
     import CMS.PrayersFixtures
@@ -19,16 +20,109 @@ defmodule CMS.PrayersTest do
       {:ok, %{user: user, scope: scope, org: org}}
     end
 
-    test "list_prayer_requests/1 returns all prayer_requests for a user's organization", %{
-      scope: scope,
-      user: user
-    } do
-      prayer_request = prayer_request_fixture(%{user: user})
+    test "list_prayer_requests/1 returns only private prayer requests for the current user" do
+      org = organization_fixture()
+      user1 = user_fixture(%{}, org)
+      user2 = user_fixture(%{}, org)
+      scope1 = user_scope_fixture(user1)
+      _scope2 = user_scope_fixture(user2)
+
+      private_request_user1 =
+        prayer_request_fixture(
+          user: user1,
+          created_by: user1,
+          organization: org,
+          visibility: :private
+        )
+
+      _private_request_user2 =
+        prayer_request_fixture(
+          user: user2,
+          created_by: user2,
+          organization: org,
+          visibility: :private
+        )
+
+      assert [request] = Prayers.list_prayer_requests(scope1)
+      assert request.id == private_request_user1.id
+    end
+
+    test "list_prayer_requests/1 returns organization-visible prayer requests" do
+      org = organization_fixture()
+      user1 = user_fixture(%{}, org)
+      user2 = user_fixture(%{}, org)
+      scope1 = user_scope_fixture(user1)
+
+      organization_request =
+        prayer_request_fixture(
+          user: user2,
+          created_by: user2,
+          organization: org,
+          visibility: :organization
+        )
+
+      assert [request] = Prayers.list_prayer_requests(scope1)
+      assert request.id == organization_request.id
+    end
+
+    test "list_prayer_requests/1 does not return requests from other organizations" do
+      org1 = organization_fixture()
+      user1 = user_fixture(%{}, org1)
+      scope1 = user_scope_fixture(user1)
 
-      # create a prayer request in another organization
-      prayer_request_fixture(%{organization: organization_fixture()})
+      org2 = organization_fixture()
+      user2 = user_fixture(%{}, org2)
 
-      assert Enum.map(Prayers.list_prayer_requests(scope), & &1.id) == [prayer_request.id]
+      _organization_request =
+        prayer_request_fixture(
+          user: user2,
+          created_by: user2,
+          organization: org2,
+          visibility: :organization
+        )
+
+      assert Prayers.list_prayer_requests(scope1) == []
+    end
+
+    test "list_prayer_requests/1 returns group-visible prayer requests for members" do
+      org = organization_fixture()
+      user1 = user_fixture(%{}, org)
+      user2 = user_fixture(%{}, org)
+      group = group_fixture(%{users: [user1, user2]}, org)
+      user1 = Repo.get(User, user1.id) |> Repo.preload([:groups, :organization])
+      scope1 = user_scope_fixture(user1)
+
+      group_request =
+        prayer_request_fixture(
+          user: user2,
+          created_by: user2,
+          organization: org,
+          group: group,
+          visibility: :group
+        )
+
+      assert [request] = Prayers.list_prayer_requests(scope1)
+      assert request.id == group_request.id
+    end
+
+    test "list_prayer_requests/1 does not return group-visible requests for non-members" do
+      org = organization_fixture()
+      user1 = user_fixture(%{}, org)
+      user2 = user_fixture(%{}, org)
+      group = group_fixture(%{users: [user2]}, org)
+      user1 = Repo.get(User, user1.id) |> Repo.preload([:groups, :organization])
+      scope1 = user_scope_fixture(user1)
+
+      _group_request =
+        prayer_request_fixture(
+          user: user2,
+          created_by: user2,
+          organization: org,
+          group: group,
+          visibility: :group
+        )
+
+      assert Prayers.list_prayer_requests(scope1) == []
     end
 
     test "create_prayer_request/2 with valid data creates a prayer_request", %{
@@ -42,29 +136,29 @@ defmodule CMS.PrayersTest do
 
       assert prayer_request.body == "some body"
       assert prayer_request.user_id == user.id
-      assert prayer_request.created_by_id == user.id
       assert prayer_request.organization_id == user.organization_id
+      assert prayer_request.visibility == :private
     end
 
-    test "create_prayer_request/2 as admin for other user", %{org: org} do
-      admin = admin_fixture(%{}, org)
-      scope = admin_scope_fixture(admin)
-      other_user = user_fixture(%{}, org)
-      valid_attrs = %{body: "some body", user_id: other_user.id}
+    test "create_prayer_request/2 with group visibility", %{org: org, user: user} do
+      group = group_fixture(%{users: [user]}, org)
+      user = Repo.get(User, user.id) |> Repo.preload([:groups, :organization])
+      scope = user_scope_fixture(user)
+      valid_attrs = %{body: "some body", visibility: :group, group_id: group.id}
 
       assert {:ok, %PrayerRequest{} = prayer_request} =
                Prayers.create_prayer_request(scope, valid_attrs)
 
-      assert prayer_request.user_id == other_user.id
-      assert prayer_request.created_by_id == admin.id
+      assert prayer_request.visibility == :group
+      assert prayer_request.group_id == group.id
     end
 
-    test "create_prayer_request/2 for user in other org", %{scope: scope} do
-      other_user = user_fixture(%{}, organization_fixture())
-      valid_attrs = %{body: "some body", user_id: other_user.id}
+    test "create_prayer_request/2 with invalid group visibility", %{org: org, scope: scope} do
+      group = group_fixture(%{}, org)
+      invalid_attrs = %{body: "some body", visibility: :group, group_id: group.id}
 
-      assert_raise RuntimeError, fn ->
-        Prayers.create_prayer_request(scope, valid_attrs)
+      assert_raise MatchError, fn ->
+        Prayers.create_prayer_request(scope, invalid_attrs)
       end
     end
 
diff --git a/test/cms_web/live/prayer_request_live/form_test.exs b/test/cms_web/live/prayer_request_live/form_test.exs
index f8ad398..4a0367c 100644
--- a/test/cms_web/live/prayer_request_live/form_test.exs
+++ b/test/cms_web/live/prayer_request_live/form_test.exs
@@ -44,40 +44,6 @@ defmodule CMSWeb.PrayerRequestLive.FormTest do
     end
   end
 
-  describe "New Prayer Request as Admin" do
-    setup [:register_and_log_in_admin]
-
-    test "as admin, shows user select", %{conn: conn, organization: org} do
-      user_fixture(%{}, org)
-
-      {:ok, view, _html} = live(conn, ~p"/prayers/new")
-
-      assert has_element?(view, "datalist#user-id-autocomplete-suggestions")
-    end
-
-    test "creates prayer request for other user", %{conn: conn, organization: org} do
-      other_user = user_fixture(%{}, org)
-
-      {:ok, view, _html} = live(conn, ~p"/prayers/new")
-
-      form_data = %{
-        "prayer_request" => %{
-          "body" => "Por favor, orem pela minha família.",
-          "user_name" => other_user.name,
-          "user_id" => other_user.id
-        }
-      }
-
-      {:ok, _redirected_view, html} =
-        view
-        |> element("#prayer-request-form")
-        |> render_submit(form_data)
-        |> follow_redirect(conn)
-
-      assert html =~ "Pedido de oração criado com sucesso."
-    end
-  end
-
   describe "authentication" do
     test "redirects unauthenticated users to the login page" do
       organization = organization_fixture()
diff --git a/test/cms_web/live/prayer_request_live_test.exs b/test/cms_web/live/prayer_request_live_test.exs
new file mode 100644
index 0000000..72e1c3a
--- /dev/null
+++ b/test/cms_web/live/prayer_request_live_test.exs
@@ -0,0 +1,33 @@
+defmodule CMSWeb.PrayerRequestLiveTest do
+  use CMSWeb.ConnCase
+
+  import Phoenix.LiveViewTest
+  import CMS.AccountsFixtures
+
+  @moduledoc """
+  E2E tests for prayer requests.
+  """
+
+  describe "new prayer request form" do
+    setup :log_in_user
+
+    test "shows and hides group selector based on visibility", %{conn: conn} do
+      {:ok, view, _html} = live(conn, ~p"/prayers/new")
+
+      refute view |> element(~s(select[name="prayer_request[group_id]"])) |> has_element?()
+
+      view
+      |> element("form")
+      |> render_change(%{prayer_request: %{visibility: "group"}})
+
+      assert view |> element(~s(select[name="prayer_request[group_id]"])) |> has_element?()
+    end
+  end
+
+  defp log_in_user(%{conn: conn}) do
+    organization = organization_fixture()
+    user = user_fixture(%{}, organization)
+    conn = log_in_user(conn, user)
+    {:ok, conn: conn, user: user}
+  end
+end
diff --git a/test/support/fixtures/accounts_fixtures.ex b/test/support/fixtures/accounts_fixtures.ex
index ac8b029..6d0ef5a 100644
--- a/test/support/fixtures/accounts_fixtures.ex
+++ b/test/support/fixtures/accounts_fixtures.ex
@@ -16,13 +16,17 @@ defmodule CMS.AccountsFixtures do
   def group_fixture(attrs \\ %{}, organization) do
     name = "Group #{System.unique_integer()}"
 
-    {:ok, group} =
+    users = attrs[:users] || []
+
+    changeset =
       %Group{
         name: name,
         organization_id: organization.id
       }
-      |> Map.merge(attrs)
-      |> Repo.insert()
+      |> Ecto.Changeset.change()
+      |> Ecto.Changeset.put_assoc(:users, users)
+
+    {:ok, group} = Repo.insert(changeset)
 
     group
   end
@@ -101,7 +105,8 @@ defmodule CMS.AccountsFixtures do
   end
 
   def user_scope_fixture(user) do
-    Scope.for_user(user, user.organization)
+    user = Repo.preload(user, [:organization, :groups])
+    Scope.for_user(user, user.organization, user.groups)
   end
 
   def admin_scope_fixture(admin) do
diff --git a/test/support/fixtures/prayers_fixtures.ex b/test/support/fixtures/prayers_fixtures.ex
index 80eb760..4910f16 100644
--- a/test/support/fixtures/prayers_fixtures.ex
+++ b/test/support/fixtures/prayers_fixtures.ex
@@ -12,17 +12,26 @@ defmodule CMS.PrayersFixtures do
   def prayer_request_fixture(attrs \\ %{}) do
     org = attrs[:organization] || organization_fixture()
     user = attrs[:user] || user_fixture(%{}, org)
-    created_by = attrs[:created_by] || user
-    scope = user_scope_fixture(created_by)
 
     attrs =
       Enum.into(attrs, %{
         body: "some body",
-        user_id: user.id
+        visibility: :private
       })
 
+    attrs =
+      if attrs.visibility == :group do
+        group = attrs[:group] || group_fixture(%{users: user}, org)
+
+        Map.put(attrs, :group_id, group.id)
+      else
+        attrs
+      end
+
+    scope = user_scope_fixture(user)
+
     {:ok, prayer_request} = CMS.Prayers.create_prayer_request(scope, attrs)
 
-    CMS.Repo.preload(prayer_request, [:user, :created_by])
+    CMS.Repo.preload(prayer_request, [:user])
   end
 end