fix: local tui mode routes console logging to a file and disables download progress bars so stray output cannot scroll the TUI

config/runtime.exs

@@ -2,8 +2,11 @@ import Config
 
 # Headless boots (BDS_MODE=server/tui, or desktop mode without a graphical
 # display — issue #33) must neuter wx before the :desktop dependency
-# application starts it and crashes the VM. Runtime config is the only hook
-# that runs before dependency applications start.
+# application starts it and crashes the VM. Local tui mode additionally
+# silences all other terminal writers (console logging goes to a file,
+# model-download progress bars are disabled) — the TUI owns the terminal
+# and every stray line scrolls its rendering up one row. Runtime config is
+# the only hook that runs before dependency applications start.
 BDS.Server.prepare_boot_env()
 
 if config_env() == :prod do

lib/bds/server.ex

@@ -67,15 +67,71 @@ defmodule BDS.Server do
   calls into no-ops, so the dependency starts inert and the TUI fallback
   (issue #33) can actually boot.
 
+  In tui mode the app additionally owns the launching terminal, so every
+  other terminal writer is silenced: the default (console) logger handler
+  is replaced with a rotating file handler at `tui_log_file/0`, and
+  Bumblebee's model-download progress bar (raw stdout writes) is disabled.
+  Each stray line would otherwise scroll the TUI's alternate screen up one
+  row and corrupt the rendering. Desktop and server modes keep logging to
+  the terminal, and SSH-served TUI sessions are unaffected either way —
+  their cells travel over the SSH channel, away from the server console.
+
   Called from `config/runtime.exs`: runtime config is the only hook that
   runs before dependency applications start, in both `mix run` and releases.
   """
-  @spec prepare_boot_env(:desktop | :server | :tui) :: :desktop | :server | :tui
-  def prepare_boot_env(mode \\ effective_mode()) do
+  @spec prepare_boot_env(:desktop | :server | :tui, (-> :ok)) :: :desktop | :server | :tui
+  def prepare_boot_env(mode \\ effective_mode(), redirect_logs \\ &redirect_logging_to_file/0) do
     if mode != :desktop, do: System.put_env("NO_WX", "1")
+
+    if mode == :tui do
+      Application.put_env(:bumblebee, :progress_bar_enabled, false)
+      redirect_logs.()
+    end
+
     mode
   end
 
+  @doc """
+  Log file that replaces console logging in local tui mode: a
+  machine-specific, regenerable artifact, so it lives in the private app
+  dir (PrivateArtifactsLiveInOsAppDir). Overridable via `:bds, :tui_log_file`.
+  """
+  @spec tui_log_file() :: Path.t()
+  def tui_log_file do
+    Application.get_env(:bds, :tui_log_file) ||
+      Path.join([BDS.Projects.private_dir(), "logs", "bds.log"])
+  end
+
+  @doc """
+  Replaces the default (console) logger handler with a rotating file
+  handler writing to `tui_log_file/0`, keeping the configured level,
+  filters, and Elixir formatter. See `prepare_boot_env/2`.
+  """
+  @spec redirect_logging_to_file() :: :ok
+  def redirect_logging_to_file do
+    log_file = tui_log_file()
+    File.mkdir_p!(Path.dirname(log_file))
+
+    with {:ok, handler} <- :logger.get_handler_config(:default) do
+      :ok = :logger.remove_handler(:default)
+
+      :ok =
+        :logger.add_handler(
+          :default,
+          :logger_std_h,
+          handler
+          |> Map.take([:level, :filters, :filter_default, :formatter])
+          |> Map.put(:config, %{
+            file: String.to_charlist(log_file),
+            max_no_bytes: 10_000_000,
+            max_no_files: 5
+          })
+        )
+    end
+
+    :ok
+  end
+
   @doc """
   Whether the HTTP endpoint requires the desktop webview auth token. Only
   desktop mode does: in server/tui mode the endpoint stays loopback-only

specs/server.allium

@@ -41,7 +41,13 @@ rule ModeResolution {
     -- never rewritten. Because the :desktop dependency boots wx in its
     -- own application start, config/runtime.exs sets NO_WX=1 for every
     -- non-desktop effective mode (BDS.Server.prepare_boot_env) so the
-    -- dependency starts inert before any BDS supervisor runs.
+    -- dependency starts inert before any BDS supervisor runs. In tui
+    -- mode prepare_boot_env also silences every other terminal writer —
+    -- the default logger handler moves to a rotating file in the private
+    -- app dir and Bumblebee's model-download progress bar is disabled —
+    -- because the TUI owns the terminal and each stray console line
+    -- scrolls the alternate screen up one row. Desktop/server modes and
+    -- SSH-served TUI sessions keep normal console logging.
     ensures: BootMode.created(kind: mode)
 }
 

test/bds/server_test.exs

@@ -88,18 +88,90 @@ defmodule BDS.ServerTest do
     end
 
     test "non-desktop modes disable wx so the :desktop dep boots inert" do
-      assert Server.prepare_boot_env(:tui) == :tui
+      assert Server.prepare_boot_env(:tui, fn -> :ok end) == :tui
       assert System.get_env("NO_WX") == "1"
 
       System.delete_env("NO_WX")
-      assert Server.prepare_boot_env(:server) == :server
+      assert Server.prepare_boot_env(:server, fn -> :ok end) == :server
       assert System.get_env("NO_WX") == "1"
     end
 
     test "desktop mode leaves wx enabled" do
-      assert Server.prepare_boot_env(:desktop) == :desktop
+      assert Server.prepare_boot_env(:desktop, fn -> :ok end) == :desktop
       assert System.get_env("NO_WX") == nil
     end
+
+    test "tui mode silences terminal writers; desktop and server modes keep them" do
+      original = Application.get_env(:bumblebee, :progress_bar_enabled)
+
+      on_exit(fn ->
+        if original == nil do
+          Application.delete_env(:bumblebee, :progress_bar_enabled)
+        else
+          Application.put_env(:bumblebee, :progress_bar_enabled, original)
+        end
+      end)
+
+      parent = self()
+
+      assert Server.prepare_boot_env(:tui, fn -> send(parent, :redirected) end) == :tui
+      assert Application.get_env(:bumblebee, :progress_bar_enabled) == false
+      assert_received :redirected
+
+      Server.prepare_boot_env(:desktop, fn -> send(parent, :redirected) end)
+      Server.prepare_boot_env(:server, fn -> send(parent, :redirected) end)
+      refute_received :redirected
+    end
+  end
+
+  describe "tui logging redirect" do
+    setup do
+      dir = Path.join(System.tmp_dir!(), "bds-tui-log-#{System.unique_integer([:positive])}")
+      log_file = Path.join(dir, "bds.log")
+      Application.put_env(:bds, :tui_log_file, log_file)
+
+      on_exit(fn ->
+        Application.delete_env(:bds, :tui_log_file)
+        File.rm_rf(dir)
+      end)
+
+      {:ok, log_file: log_file}
+    end
+
+    test "tui_log_file defaults to the private app dir and honors the override", %{
+      log_file: log_file
+    } do
+      assert Server.tui_log_file() == log_file
+
+      Application.delete_env(:bds, :tui_log_file)
+      assert Server.tui_log_file() == Path.join([BDS.Projects.private_dir(), "logs", "bds.log"])
+    end
+
+    test "redirect_logging_to_file swaps the default handler to a rotating file handler", %{
+      log_file: log_file
+    } do
+      {:ok, original} = :logger.get_handler_config(:default)
+
+      on_exit(fn ->
+        _ = :logger.remove_handler(:default)
+
+        :ok =
+          :logger.add_handler(
+            :default,
+            original.module,
+            Map.take(original, [:level, :filters, :filter_default, :formatter, :config])
+          )
+      end)
+
+      assert Server.redirect_logging_to_file() == :ok
+
+      {:ok, handler} = :logger.get_handler_config(:default)
+      assert handler.module == :logger_std_h
+      assert handler.config.file == String.to_charlist(log_file)
+      assert handler.config.max_no_bytes > 0
+      # The swap must keep the Elixir log formatter, not fall back to OTP's.
+      assert handler.formatter == original.formatter
+    end
   end
 
   describe "ensure_ssh_dir!/1" do