From 848b3f5d5b6e004c51e18a4adb04d721fb89ea5c Mon Sep 17 00:00:00 2001
From: Yonle <yonle@proton.me>
Date: Mon, 23 Feb 2026 20:57:11 +0700
Subject: [PATCH 01/13] reverse_proxy,endpoint,uploaded_media: add immutable
 cache-control flag

---
 lib/pleroma/reverse_proxy.ex            | 2 +-
 lib/pleroma/web/endpoint.ex             | 2 +-
 lib/pleroma/web/plugs/uploaded_media.ex | 2 +-
 test/pleroma/reverse_proxy_test.exs     | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/pleroma/reverse_proxy.ex b/lib/pleroma/reverse_proxy.ex
index bb55a4984..c7ee47c6e 100644
--- a/lib/pleroma/reverse_proxy.ex
+++ b/lib/pleroma/reverse_proxy.ex
@@ -12,7 +12,7 @@ defmodule Pleroma.ReverseProxy do
   @keep_resp_headers @resp_cache_headers ++
                        ~w(content-length content-type content-disposition content-encoding) ++
                        ~w(content-range accept-ranges vary)
-  @default_cache_control_header "public, max-age=1209600"
+  @default_cache_control_header "public, max-age=1209600, immutable"
   @valid_resp_codes [200, 206, 304]
   @max_read_duration :timer.seconds(30)
   @max_body_length :infinity
diff --git a/lib/pleroma/web/endpoint.ex b/lib/pleroma/web/endpoint.ex
index bab3c9fd0..13c655ee2 100644
--- a/lib/pleroma/web/endpoint.ex
+++ b/lib/pleroma/web/endpoint.ex
@@ -46,7 +46,7 @@ defmodule Pleroma.Web.Endpoint do
   plug(Pleroma.Web.Plugs.HTTPSecurityPlug)
   plug(Pleroma.Web.Plugs.UploadedMedia)
 
-  @static_cache_control "public, max-age=1209600"
+  @static_cache_control "public, max-age=1209600, immutable"
   @static_cache_disabled "public, no-cache"
 
   # InstanceStatic needs to be before Plug.Static to be able to override shipped-static files
diff --git a/lib/pleroma/web/plugs/uploaded_media.ex b/lib/pleroma/web/plugs/uploaded_media.ex
index abacf965b..5a3ea12aa 100644
--- a/lib/pleroma/web/plugs/uploaded_media.ex
+++ b/lib/pleroma/web/plugs/uploaded_media.ex
@@ -17,7 +17,7 @@ defmodule Pleroma.Web.Plugs.UploadedMedia do
   # no slashes
   @path "media"
 
-  @default_cache_control_header "public, max-age=1209600"
+  @default_cache_control_header "public, max-age=1209600, immutable"
 
   def init(_opts) do
     static_plug_opts =
diff --git a/test/pleroma/reverse_proxy_test.exs b/test/pleroma/reverse_proxy_test.exs
index 8dbe9c6bf..ec4470379 100644
--- a/test/pleroma/reverse_proxy_test.exs
+++ b/test/pleroma/reverse_proxy_test.exs
@@ -294,7 +294,7 @@ defmodule Pleroma.ReverseProxyTest do
       |> expect(:stream_body, fn _ -> :done end)
 
       conn = ReverseProxy.call(conn, "/cache")
-      assert {"cache-control", "public, max-age=1209600"} in conn.resp_headers
+      assert {"cache-control", "public, max-age=1209600, immutable"} in conn.resp_headers
     end
   end
 

From 970e0f90441ff092fd6ee11ed0a87a06f4269373 Mon Sep 17 00:00:00 2001
From: Yonle <yonle@proton.me>
Date: Mon, 2 Mar 2026 23:48:59 +0700
Subject: [PATCH 02/13] endpoint: set cache control for favicon.png

Signed-off-by: Yonle <yonle@proton.me>
---
 lib/pleroma/web/endpoint.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/pleroma/web/endpoint.ex b/lib/pleroma/web/endpoint.ex
index 13c655ee2..f7c58f459 100644
--- a/lib/pleroma/web/endpoint.ex
+++ b/lib/pleroma/web/endpoint.ex
@@ -56,7 +56,7 @@ defmodule Pleroma.Web.Endpoint do
     Pleroma.Web.Plugs.InstanceStatic,
     at: "/",
     from: :pleroma,
-    only: ["emoji", "images"],
+    only: ["emoji", "images", "favicon.png"],
     gzip: true,
     cache_control_for_etags: @static_cache_control,
     headers: %{

From 8abd25950a483efcfa42ba113086dd6cc5730ebf Mon Sep 17 00:00:00 2001
From: Yonle <yonle@proton.me>
Date: Wed, 4 Mar 2026 02:54:47 +0700
Subject: [PATCH 03/13] endpoint: use favicon plug

---
 lib/pleroma/web/endpoint.ex      | 12 +++++-
 lib/pleroma/web/plugs/favicon.ex | 73 ++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+), 1 deletion(-)
 create mode 100644 lib/pleroma/web/plugs/favicon.ex

diff --git a/lib/pleroma/web/endpoint.ex b/lib/pleroma/web/endpoint.ex
index f7c58f459..e769b11b1 100644
--- a/lib/pleroma/web/endpoint.ex
+++ b/lib/pleroma/web/endpoint.ex
@@ -48,6 +48,7 @@ defmodule Pleroma.Web.Endpoint do
 
   @static_cache_control "public, max-age=1209600, immutable"
   @static_cache_disabled "public, no-cache"
+  @favicon_cache_control "public, max=age=86400, immutable" # cache for a day
 
   # InstanceStatic needs to be before Plug.Static to be able to override shipped-static files
   # If you're adding new paths to `only:` you'll need to configure them in InstanceStatic as well
@@ -56,7 +57,7 @@ defmodule Pleroma.Web.Endpoint do
     Pleroma.Web.Plugs.InstanceStatic,
     at: "/",
     from: :pleroma,
-    only: ["emoji", "images", "favicon.png"],
+    only: ["emoji", "images"],
     gzip: true,
     cache_control_for_etags: @static_cache_control,
     headers: %{
@@ -73,6 +74,15 @@ defmodule Pleroma.Web.Endpoint do
     }
   )
 
+  plug(Pleroma.Web.Plugs.Favicon,
+    at: "/",
+    only: ["favicon.png"],
+    cache_control_for_etags: @favicon_cache_control,
+    headers: %{
+      "cache-control" => @favicon_cache_control
+    }
+  )
+
   plug(Pleroma.Web.Plugs.FrontendStatic,
     at: "/",
     frontend_type: :primary,
diff --git a/lib/pleroma/web/plugs/favicon.ex b/lib/pleroma/web/plugs/favicon.ex
new file mode 100644
index 000000000..ad105c59a
--- /dev/null
+++ b/lib/pleroma/web/plugs/favicon.ex
@@ -0,0 +1,73 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2026 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.Plugs.Favicon do
+  @behaviour Plug
+
+  @moduledoc """
+  Serves favicon.png directly from the instance static directory,
+  bypassing the frontend-specific logic.
+  """
+
+  alias Pleroma.Web.Plugs.FrontendStatic
+  import Plug.Conn, only: [put_resp_header: 3]
+
+  def init(opts) do
+    opts
+    |> Keyword.put(:from, "__unconfigured_favicon_static_plug")
+    |> Plug.Static.init()
+  end
+
+  def call(conn, opts) do
+    if favicon_route?(conn.path_info) do
+      case find_favicon_dir(conn) do
+        {:ok, dir} ->
+          call_static(conn, opts, dir)
+          |> Plug.Conn.halt()
+
+        :error ->
+          conn # Let the request keep going to a 404
+      end
+    else
+      conn
+    end
+  end
+
+  defp find_favicon_dir(conn) do
+    instance_dir = Pleroma.Config.get([:instance, :static_dir], "instance/static")
+    instance_path = Path.join(instance_dir, "favicon.png")
+
+    frontend_type = FrontendStatic.preferred_or_fallback(conn, :primary)
+    frontend_dir = FrontendStatic.file_path("", frontend_type)
+    frontend_path = if frontend_dir, do: Path.join(frontend_dir, "favicon.png"), else: nil
+
+    priv_dir = Application.app_dir(:pleroma, "priv/static")
+    priv_path = Path.join(priv_dir, "favicon.png")
+
+    cond do
+      File.exists?(instance_path) -> {:ok, instance_dir}
+      frontend_path && File.exists?(frontend_path) -> {:ok, frontend_dir}
+      File.exists?(priv_path) -> {:ok, priv_dir}
+      true -> :error
+    end
+  end
+
+  defp favicon_route?(["favicon.png"]), do: true
+  defp favicon_route?(_), do: false
+
+  defp call_static(conn, opts, from) do
+    opts =
+      opts
+      |> Map.put(:from, from)
+      |> Map.put(:content_types, false)
+
+    conn = set_content_type(conn)
+
+    Plug.Static.call(conn, opts)
+  end
+
+  defp set_content_type(conn) do
+    put_resp_header(conn, "content-type", "image/png")
+  end
+end

From 4bc0b26abed50ca04041297f1f66467a8d812359 Mon Sep 17 00:00:00 2001
From: Yonle <yonle@proton.me>
Date: Wed, 4 Mar 2026 02:57:53 +0700
Subject: [PATCH 04/13] changelog.d: add cache-control-immutable

---
 changelog.d/cache-control-immutable.add | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/cache-control-immutable.add

diff --git a/changelog.d/cache-control-immutable.add b/changelog.d/cache-control-immutable.add
new file mode 100644
index 000000000..516db67bf
--- /dev/null
+++ b/changelog.d/cache-control-immutable.add
@@ -0,0 +1 @@
+Add immutable tag on cache-control header for several endpoints that's serving the same exact things.
\ No newline at end of file

From 0879dd39505bb9f577bd371a04f49b9beb2123ae Mon Sep 17 00:00:00 2001
From: Yonle <yonle@proton.me>
Date: Wed, 4 Mar 2026 03:13:55 +0700
Subject: [PATCH 05/13] endpoint: reorder: handle favicon plug first

---
 lib/pleroma/web/endpoint.ex | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/lib/pleroma/web/endpoint.ex b/lib/pleroma/web/endpoint.ex
index e769b11b1..2bf64a1fd 100644
--- a/lib/pleroma/web/endpoint.ex
+++ b/lib/pleroma/web/endpoint.ex
@@ -65,15 +65,6 @@ defmodule Pleroma.Web.Endpoint do
     }
   )
 
-  plug(Pleroma.Web.Plugs.InstanceStatic,
-    at: "/",
-    gzip: true,
-    cache_control_for_etags: @static_cache_disabled,
-    headers: %{
-      "cache-control" => @static_cache_disabled
-    }
-  )
-
   plug(Pleroma.Web.Plugs.Favicon,
     at: "/",
     only: ["favicon.png"],
@@ -83,6 +74,15 @@ defmodule Pleroma.Web.Endpoint do
     }
   )
 
+  plug(Pleroma.Web.Plugs.InstanceStatic,
+    at: "/",
+    gzip: true,
+    cache_control_for_etags: @static_cache_disabled,
+    headers: %{
+      "cache-control" => @static_cache_disabled
+    }
+  )
+
   plug(Pleroma.Web.Plugs.FrontendStatic,
     at: "/",
     frontend_type: :primary,

From 96f252023e31549d934b42c098d6e62192f9f8d0 Mon Sep 17 00:00:00 2001
From: Yonle <yonle@proton.me>
Date: Wed, 4 Mar 2026 22:49:54 +0700
Subject: [PATCH 06/13] constants: remove favicon.png from static_only_files

---
 lib/pleroma/constants.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/pleroma/constants.ex b/lib/pleroma/constants.ex
index f78b84099..178dd6094 100644
--- a/lib/pleroma/constants.ex
+++ b/lib/pleroma/constants.ex
@@ -29,7 +29,7 @@ defmodule Pleroma.Constants do
 
   const(static_only_files,
     do:
-      ~w(index.html robots.txt static static-fe finmoji emoji packs sounds images instance sw.js sw-pleroma.js favicon.png schemas doc embed.js embed.css)
+      ~w(index.html robots.txt static static-fe finmoji emoji packs sounds images instance sw.js sw-pleroma.js schemas doc embed.js embed.css)
   )
 
   const(status_updatable_fields,

From 89751296803ba60354c16335f3422421710ddb00 Mon Sep 17 00:00:00 2001
From: Yonle <yonle@proton.me>
Date: Thu, 5 Mar 2026 02:07:39 +0700
Subject: [PATCH 07/13] webplug(favicon): remove check on url path.

---
 lib/pleroma/web/plugs/favicon.ex | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/lib/pleroma/web/plugs/favicon.ex b/lib/pleroma/web/plugs/favicon.ex
index ad105c59a..32ef86cf8 100644
--- a/lib/pleroma/web/plugs/favicon.ex
+++ b/lib/pleroma/web/plugs/favicon.ex
@@ -20,17 +20,12 @@ defmodule Pleroma.Web.Plugs.Favicon do
   end
 
   def call(conn, opts) do
-    if favicon_route?(conn.path_info) do
-      case find_favicon_dir(conn) do
-        {:ok, dir} ->
-          call_static(conn, opts, dir)
-          |> Plug.Conn.halt()
+    case find_favicon_dir(conn) do
+      {:ok, dir} ->
+        call_static(conn, opts, dir)
 
-        :error ->
-          conn # Let the request keep going to a 404
-      end
-    else
-      conn
+      :error ->
+        conn # Let the request keep going to a 404
     end
   end
 
@@ -53,9 +48,6 @@ defmodule Pleroma.Web.Plugs.Favicon do
     end
   end
 
-  defp favicon_route?(["favicon.png"]), do: true
-  defp favicon_route?(_), do: false
-
   defp call_static(conn, opts, from) do
     opts =
       opts

From d03ae43ee07a8d6467fe8b608ba69f2166a740e3 Mon Sep 17 00:00:00 2001
From: Phantasm <phantasm@centrum.cz>
Date: Thu, 5 Mar 2026 10:28:09 +0100
Subject: [PATCH 08/13] Favicon Plug: Simplify and pass when not requesting
 favicon

---
 lib/pleroma/web/plugs/favicon.ex | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/lib/pleroma/web/plugs/favicon.ex b/lib/pleroma/web/plugs/favicon.ex
index 32ef86cf8..6564d2e00 100644
--- a/lib/pleroma/web/plugs/favicon.ex
+++ b/lib/pleroma/web/plugs/favicon.ex
@@ -10,7 +10,6 @@ defmodule Pleroma.Web.Plugs.Favicon do
   bypassing the frontend-specific logic.
   """
 
-  alias Pleroma.Web.Plugs.FrontendStatic
   import Plug.Conn, only: [put_resp_header: 3]
 
   def init(opts) do
@@ -19,8 +18,8 @@ defmodule Pleroma.Web.Plugs.Favicon do
     |> Plug.Static.init()
   end
 
-  def call(conn, opts) do
-    case find_favicon_dir(conn) do
+  def call(%{request_path: "/favicon.png"} = conn, opts) do
+    case find_favicon_dir() do
       {:ok, dir} ->
         call_static(conn, opts, dir)
 
@@ -29,20 +28,19 @@ defmodule Pleroma.Web.Plugs.Favicon do
     end
   end
 
-  defp find_favicon_dir(conn) do
+  def call(conn, _) do
+    conn
+  end
+
+  defp find_favicon_dir() do
     instance_dir = Pleroma.Config.get([:instance, :static_dir], "instance/static")
     instance_path = Path.join(instance_dir, "favicon.png")
 
-    frontend_type = FrontendStatic.preferred_or_fallback(conn, :primary)
-    frontend_dir = FrontendStatic.file_path("", frontend_type)
-    frontend_path = if frontend_dir, do: Path.join(frontend_dir, "favicon.png"), else: nil
-
     priv_dir = Application.app_dir(:pleroma, "priv/static")
     priv_path = Path.join(priv_dir, "favicon.png")
 
     cond do
       File.exists?(instance_path) -> {:ok, instance_dir}
-      frontend_path && File.exists?(frontend_path) -> {:ok, frontend_dir}
       File.exists?(priv_path) -> {:ok, priv_dir}
       true -> :error
     end

From 2388964b141bb963d1ab37ccdd00985140a2c6aa Mon Sep 17 00:00:00 2001
From: Phantasm <phantasm@centrum.cz>
Date: Thu, 5 Mar 2026 11:37:02 +0100
Subject: [PATCH 09/13] Favicon Plug: Add tests

---
 test/pleroma/web/plugs/favicon_plug_test.exs | 69 ++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 test/pleroma/web/plugs/favicon_plug_test.exs

diff --git a/test/pleroma/web/plugs/favicon_plug_test.exs b/test/pleroma/web/plugs/favicon_plug_test.exs
new file mode 100644
index 000000000..36650e7bf
--- /dev/null
+++ b/test/pleroma/web/plugs/favicon_plug_test.exs
@@ -0,0 +1,69 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2026 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.Plugs.FaviconPlugTest do
+  use Pleroma.Web.ConnCase
+
+  # import Mox
+
+  # alias Pleroma.UnstubbedConfigMock, as: ConfigMock
+
+  @dir "test/tmp/favicon_static"
+
+  describe "default favicon" do
+    test "returns favicon", %{conn: conn} do
+      conn = get(conn, "/favicon.png")
+      etag = get_resp_header(conn, "etag")
+
+      # etag changes when serving a different file
+      assert etag == ["\"72487CE\""]
+      assert response_content_type(conn, :png)
+    end
+
+    test "returns correct cache-control", %{conn: conn} do
+      cache = 
+        conn
+        |> get("/favicon.png")
+        |> get_resp_header("cache-control")
+
+      assert cache == ["public, max=age=86400, immutable"]
+    end
+  end
+
+  describe "custom favicon" do
+    setup do
+      Pleroma.Backports.mkdir_p!(@dir)
+      favicon_path = Path.join(@dir, "favicon.png")
+
+      # Favicon plug should always return image/png
+      donor_image = "test/fixtures/image.gif"
+      image_stat = File.stat!(donor_image)
+
+      # Preserve stat since that's what etag is based on
+      File.cp!(donor_image, favicon_path)
+      File.write_stat!(favicon_path, image_stat)
+
+      clear_config([:instance, :static_dir], @dir)
+
+      on_exit( fn -> File.rm_rf!(@dir) end)
+    end
+
+    test "returns favicon", %{conn: conn} do
+      conn = get(conn, "/favicon.png")
+      etag = get_resp_header(conn, "etag")
+
+      assert etag == ["\"215A3A4\""]
+      assert response_content_type(conn, :png)
+    end
+
+    test "returns correct cache-control", %{conn: conn} do
+      cache =
+       conn
+       |> get("/favicon.png")
+       |> get_resp_header("cache-control")
+
+      assert cache == ["public, max=age=86400, immutable"]
+    end
+  end
+end

From 662c9f36ac597c7f0bfbcdec8c12f2dfb87b8df0 Mon Sep 17 00:00:00 2001
From: Phantasm <phantasm@centrum.cz>
Date: Thu, 5 Mar 2026 11:43:55 +0100
Subject: [PATCH 10/13] Favicon Plug: Update moduledoc and rename to adhere to
 convention

---
 lib/pleroma/web/endpoint.ex                           | 2 +-
 lib/pleroma/web/plugs/{favicon.ex => favicon_plug.ex} | 7 ++++---
 2 files changed, 5 insertions(+), 4 deletions(-)
 rename lib/pleroma/web/plugs/{favicon.ex => favicon_plug.ex} (86%)

diff --git a/lib/pleroma/web/endpoint.ex b/lib/pleroma/web/endpoint.ex
index 2bf64a1fd..81a9d3a09 100644
--- a/lib/pleroma/web/endpoint.ex
+++ b/lib/pleroma/web/endpoint.ex
@@ -65,7 +65,7 @@ defmodule Pleroma.Web.Endpoint do
     }
   )
 
-  plug(Pleroma.Web.Plugs.Favicon,
+  plug(Pleroma.Web.Plugs.FaviconPlug,
     at: "/",
     only: ["favicon.png"],
     cache_control_for_etags: @favicon_cache_control,
diff --git a/lib/pleroma/web/plugs/favicon.ex b/lib/pleroma/web/plugs/favicon_plug.ex
similarity index 86%
rename from lib/pleroma/web/plugs/favicon.ex
rename to lib/pleroma/web/plugs/favicon_plug.ex
index 6564d2e00..d50a03d83 100644
--- a/lib/pleroma/web/plugs/favicon.ex
+++ b/lib/pleroma/web/plugs/favicon_plug.ex
@@ -2,12 +2,13 @@
 # Copyright © 2017-2026 Pleroma Authors <https://pleroma.social/>
 # SPDX-License-Identifier: AGPL-3.0-only
 
-defmodule Pleroma.Web.Plugs.Favicon do
+defmodule Pleroma.Web.Plugs.FaviconPlug do
   @behaviour Plug
 
   @moduledoc """
-  Serves favicon.png directly from the instance static directory,
-  bypassing the frontend-specific logic.
+  This is a shim to call `Plug.Static` but with runtime `from` configuration for instance favicon.
+
+  Serves default or custom favicon.png with cacheable cache-control.
   """
 
   import Plug.Conn, only: [put_resp_header: 3]

From d0db1f00c3d52cab72de6db300bb99d58b1f289a Mon Sep 17 00:00:00 2001
From: Phantasm <phantasm@centrum.cz>
Date: Thu, 5 Mar 2026 11:55:02 +0100
Subject: [PATCH 11/13] Favicon Plug: assert HTTP 200 status in tests

---
 test/pleroma/web/plugs/favicon_plug_test.exs | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/test/pleroma/web/plugs/favicon_plug_test.exs b/test/pleroma/web/plugs/favicon_plug_test.exs
index 36650e7bf..87d955ccc 100644
--- a/test/pleroma/web/plugs/favicon_plug_test.exs
+++ b/test/pleroma/web/plugs/favicon_plug_test.exs
@@ -17,16 +17,16 @@ defmodule Pleroma.Web.Plugs.FaviconPlugTest do
       etag = get_resp_header(conn, "etag")
 
       # etag changes when serving a different file
+      assert conn.status == 200
       assert etag == ["\"72487CE\""]
       assert response_content_type(conn, :png)
     end
 
     test "returns correct cache-control", %{conn: conn} do
-      cache = 
-        conn
-        |> get("/favicon.png")
-        |> get_resp_header("cache-control")
+      conn = get(conn, "/favicon.png")
+      cache = get_resp_header(conn, "cache-control")
 
+      assert conn.status == 200
       assert cache == ["public, max=age=86400, immutable"]
     end
   end
@@ -53,16 +53,16 @@ defmodule Pleroma.Web.Plugs.FaviconPlugTest do
       conn = get(conn, "/favicon.png")
       etag = get_resp_header(conn, "etag")
 
+      assert conn.status == 200
       assert etag == ["\"215A3A4\""]
       assert response_content_type(conn, :png)
     end
 
     test "returns correct cache-control", %{conn: conn} do
-      cache =
-       conn
-       |> get("/favicon.png")
-       |> get_resp_header("cache-control")
+      conn = get(conn ,"/favicon.png")
+      cache = get_resp_header(conn, "cache-control")
 
+      assert conn.status == 200
       assert cache == ["public, max=age=86400, immutable"]
     end
   end

From 5f321b0b5b10d0a3324b588b8f9af01878ecac04 Mon Sep 17 00:00:00 2001
From: Phantasm <phantasm@centrum.cz>
Date: Thu, 5 Mar 2026 12:49:20 +0100
Subject: [PATCH 12/13] Favicon Plug: Halt Plug pipeline when favicon not found

---
 lib/pleroma/web/plugs/favicon_plug.ex        | 12 ++++++--
 test/pleroma/web/plugs/favicon_plug_test.exs | 30 ++++++++------------
 2 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/lib/pleroma/web/plugs/favicon_plug.ex b/lib/pleroma/web/plugs/favicon_plug.ex
index d50a03d83..1f8b891a1 100644
--- a/lib/pleroma/web/plugs/favicon_plug.ex
+++ b/lib/pleroma/web/plugs/favicon_plug.ex
@@ -11,7 +11,9 @@ defmodule Pleroma.Web.Plugs.FaviconPlug do
   Serves default or custom favicon.png with cacheable cache-control.
   """
 
-  import Plug.Conn, only: [put_resp_header: 3]
+  import Plug.Conn, only: [put_resp_header: 3, send_resp: 3, halt: 1]
+
+  require Logger
 
   def init(opts) do
     opts
@@ -25,7 +27,12 @@ defmodule Pleroma.Web.Plugs.FaviconPlug do
         call_static(conn, opts, dir)
 
       :error ->
-        conn # Let the request keep going to a 404
+        # Favicon should always be available and this should never occur.
+        # If it does, halt the pipeline before having unintended side-effects.
+        Logger.error("No favicon.png found! Is the default favicon deleted?")
+        conn
+        |> send_resp(404, "Not found")
+        |> halt()
     end
   end
 
@@ -54,7 +61,6 @@ defmodule Pleroma.Web.Plugs.FaviconPlug do
       |> Map.put(:content_types, false)
 
     conn = set_content_type(conn)
-
     Plug.Static.call(conn, opts)
   end
 
diff --git a/test/pleroma/web/plugs/favicon_plug_test.exs b/test/pleroma/web/plugs/favicon_plug_test.exs
index 87d955ccc..62926e041 100644
--- a/test/pleroma/web/plugs/favicon_plug_test.exs
+++ b/test/pleroma/web/plugs/favicon_plug_test.exs
@@ -5,20 +5,21 @@
 defmodule Pleroma.Web.Plugs.FaviconPlugTest do
   use Pleroma.Web.ConnCase
 
-  # import Mox
-
-  # alias Pleroma.UnstubbedConfigMock, as: ConfigMock
-
   @dir "test/tmp/favicon_static"
 
+  setup do
+      Pleroma.Backports.mkdir_p!(@dir)
+
+      on_exit(fn -> File.rm_rf!(@dir) end)
+  end
+
   describe "default favicon" do
     test "returns favicon", %{conn: conn} do
       conn = get(conn, "/favicon.png")
-      etag = get_resp_header(conn, "etag")
+      body_size = byte_size(conn.resp_body)
 
-      # etag changes when serving a different file
       assert conn.status == 200
-      assert etag == ["\"72487CE\""]
+      assert body_size == 1583
       assert response_content_type(conn, :png)
     end
 
@@ -33,28 +34,21 @@ defmodule Pleroma.Web.Plugs.FaviconPlugTest do
 
   describe "custom favicon" do
     setup do
-      Pleroma.Backports.mkdir_p!(@dir)
       favicon_path = Path.join(@dir, "favicon.png")
+      donor_image = "test/fixtures/image.png"
 
-      # Favicon plug should always return image/png
-      donor_image = "test/fixtures/image.gif"
-      image_stat = File.stat!(donor_image)
-
-      # Preserve stat since that's what etag is based on
       File.cp!(donor_image, favicon_path)
-      File.write_stat!(favicon_path, image_stat)
-
       clear_config([:instance, :static_dir], @dir)
 
-      on_exit( fn -> File.rm_rf!(@dir) end)
+      on_exit(fn -> File.rm!(favicon_path) end)
     end
 
     test "returns favicon", %{conn: conn} do
       conn = get(conn, "/favicon.png")
-      etag = get_resp_header(conn, "etag")
+      body_size = byte_size(conn.resp_body)
 
       assert conn.status == 200
-      assert etag == ["\"215A3A4\""]
+      assert body_size == 104426
       assert response_content_type(conn, :png)
     end
 

From 3760480813745c0f2d0b2fe1a8642400308e2be2 Mon Sep 17 00:00:00 2001
From: Phantasm <phantasm@centrum.cz>
Date: Thu, 5 Mar 2026 11:48:37 +0100
Subject: [PATCH 13/13] lint

---
 lib/pleroma/web/plugs/favicon_plug.ex        | 3 ++-
 test/pleroma/web/plugs/favicon_plug_test.exs | 8 ++++----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/lib/pleroma/web/plugs/favicon_plug.ex b/lib/pleroma/web/plugs/favicon_plug.ex
index 1f8b891a1..e2e1f1adb 100644
--- a/lib/pleroma/web/plugs/favicon_plug.ex
+++ b/lib/pleroma/web/plugs/favicon_plug.ex
@@ -30,6 +30,7 @@ defmodule Pleroma.Web.Plugs.FaviconPlug do
         # Favicon should always be available and this should never occur.
         # If it does, halt the pipeline before having unintended side-effects.
         Logger.error("No favicon.png found! Is the default favicon deleted?")
+
         conn
         |> send_resp(404, "Not found")
         |> halt()
@@ -40,7 +41,7 @@ defmodule Pleroma.Web.Plugs.FaviconPlug do
     conn
   end
 
-  defp find_favicon_dir() do
+  defp find_favicon_dir do
     instance_dir = Pleroma.Config.get([:instance, :static_dir], "instance/static")
     instance_path = Path.join(instance_dir, "favicon.png")
 
diff --git a/test/pleroma/web/plugs/favicon_plug_test.exs b/test/pleroma/web/plugs/favicon_plug_test.exs
index 62926e041..520501250 100644
--- a/test/pleroma/web/plugs/favicon_plug_test.exs
+++ b/test/pleroma/web/plugs/favicon_plug_test.exs
@@ -8,9 +8,9 @@ defmodule Pleroma.Web.Plugs.FaviconPlugTest do
   @dir "test/tmp/favicon_static"
 
   setup do
-      Pleroma.Backports.mkdir_p!(@dir)
+    Pleroma.Backports.mkdir_p!(@dir)
 
-      on_exit(fn -> File.rm_rf!(@dir) end)
+    on_exit(fn -> File.rm_rf!(@dir) end)
   end
 
   describe "default favicon" do
@@ -48,12 +48,12 @@ defmodule Pleroma.Web.Plugs.FaviconPlugTest do
       body_size = byte_size(conn.resp_body)
 
       assert conn.status == 200
-      assert body_size == 104426
+      assert body_size == 104_426
       assert response_content_type(conn, :png)
     end
 
     test "returns correct cache-control", %{conn: conn} do
-      conn = get(conn ,"/favicon.png")
+      conn = get(conn, "/favicon.png")
       cache = get_resp_header(conn, "cache-control")
 
       assert conn.status == 200