diff --git a/bin/omarchy-install-ai-t3-code b/bin/omarchy-install-ai-t3-code
index e93e9b15..b9e3af38 100755
--- a/bin/omarchy-install-ai-t3-code
+++ b/bin/omarchy-install-ai-t3-code
@@ -7,40 +7,22 @@ set -e
 
 T3CODE_HOME="${T3CODE_HOME:-$HOME/.t3}"
 T3CODE_STATE_DIR="$T3CODE_HOME/userdata"
-T3CODE_SETTINGS_PATH="$T3CODE_STATE_DIR/settings.json"
-
-# Ask T3 Code to open on the palette this machine publishes. `t3 theme set`
-# is the supported way, but the desktop package ships only the GUI -- the CLI
-# is a separate npm distribution -- so fall back to the setting it writes.
-# Both run before the first launch, so neither races a running server.
-set_default_theme() {
-  if omarchy-cmd-present t3; then
-    t3 theme set omarchy --base-dir "$T3CODE_HOME" >/dev/null && return
-  fi
-
-  local tmp
-  mkdir -p "$T3CODE_STATE_DIR"
-  [[ -f $T3CODE_SETTINGS_PATH ]] || echo '{}' >"$T3CODE_SETTINGS_PATH"
-
-  tmp=$(mktemp "$T3CODE_SETTINGS_PATH.XXXXXX")
-  if jq '.defaultTheme = "omarchy"' "$T3CODE_SETTINGS_PATH" >"$tmp"; then
-    mv "$tmp" "$T3CODE_SETTINGS_PATH"
-  else
-    rm -f "$tmp"
-    echo "Could not set the default theme in $T3CODE_SETTINGS_PATH." >&2
-  fi
-}
 
 echo "Installing T3 Code..."
 omarchy-pkg-add t3code-bin
 
-# The palette itself, and the request to open on it, are both first-run
-# concerns. `defaultTheme` only decides what a client with no theme of its own
-# starts on, so choosing a theme in T3 Code later is never overridden.
 echo "Matching T3 Code to the current theme..."
 mkdir -p "$T3CODE_STATE_DIR"
+
+# An updated user's current theme may have been staged before this template existed.
+if [[ ! -f $HOME/.local/state/omarchy/current/theme/t3code.json ]]; then
+  omarchy-theme-refresh
+fi
+
 omarchy-theme-set-t3code
-set_default_theme
+
+# The packaged CLI selects the published palette before the app's first launch.
+t3 theme set omarchy --base-dir "$T3CODE_HOME"
 
 echo "Opening T3 Code..."
 setsid uwsm-app -- gtk-launch t3code >/dev/null 2>&1 &
diff --git a/test/shell.d/t3code-install-test.sh b/test/shell.d/t3code-install-test.sh
new file mode 100755
index 00000000..66bc9ecd
--- /dev/null
+++ b/test/shell.d/t3code-install-test.sh
@@ -0,0 +1,81 @@
+#!/bin/bash
+
+set -euo pipefail
+
+source "$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)/base-test.sh"
+
+test_tmp=$(mktemp -d)
+trap 'rm -rf "$test_tmp"' EXIT
+
+test_home="$test_tmp/home"
+mock_bin="$test_tmp/bin"
+mkdir -p "$mock_bin"
+
+# Run the real theme refresh, renderer and publisher in a throwaway home.
+# Only package installation, the T3 CLI and desktop launch are stubbed.
+cat >"$mock_bin/omarchy-pkg-add" <<'SH'
+#!/bin/bash
+[[ $1 == "t3code-bin" ]]
+SH
+
+cat >"$mock_bin/t3" <<'SH'
+#!/bin/bash
+[[ $1 == "theme" && $2 == "set" && $3 == "omarchy" && $4 == "--base-dir" && $5 == "$T3CODE_HOME" ]] || exit 1
+palette="$T3CODE_HOME/userdata/themes/omarchy.json"
+if [[ ! -f $palette ]] || ! jq -e '.name == "Omarchy" and (.accent | test("^#[0-9a-fA-F]{6}$"))' "$palette" >/dev/null; then
+  echo "No published Omarchy theme"
+  exit 1
+fi
+if [[ ${OMARCHY_TEST_T3_FAIL:-0} == "1" ]]; then
+  echo "T3 theme selection failed"
+  exit 1
+fi
+echo "T3 selected Omarchy"
+SH
+
+cat >"$mock_bin/setsid" <<'SH'
+#!/bin/bash
+exit 0
+SH
+chmod +x "$mock_bin"/*
+
+run_installer() {
+  HOME="$test_home" T3CODE_HOME="$test_tmp/custom t3 home" \
+    OMARCHY_PATH="$ROOT" PATH="$mock_bin:$ROOT/bin:$PATH" \
+    OMARCHY_THEME_HEADLESS=1 XDG_RUNTIME_DIR="$test_tmp" \
+    "$ROOT/bin/omarchy-install-ai-t3-code" >"$test_tmp/output" 2>&1
+}
+
+state="$test_home/.local/state/omarchy/current"
+palette="$test_tmp/custom t3 home/userdata/themes/omarchy.json"
+settings="$test_tmp/custom t3 home/userdata/settings.json"
+mkdir -p "$state/theme"
+echo 'tokyo-night' >"$state/theme.name"
+cp "$ROOT/themes/tokyo-night/colors.toml" "$state/theme/colors.toml"
+
+run_installer || fail "installing after an update succeeds" "$(cat "$test_tmp/output")"
+[[ -f $state/theme/t3code.json && -f $palette ]] || fail "the missing palette is rendered and published"
+cmp -s "$state/theme/t3code.json" "$palette" || fail "T3 receives the current theme's palette"
+grep -q 'T3 selected Omarchy' "$test_tmp/output" || fail "the published palette is selected"
+grep -q 'Opening T3 Code' "$test_tmp/output" || fail "the themed app opens"
+[[ ! -e $test_home/.t3 ]] || fail "the custom T3 home is respected"
+pass "an update with no staged T3 palette renders, publishes and selects it before launch"
+
+# Preserve an already rendered palette, including a user-supplied color.
+jq '.accent = "#abcdef"' "$state/theme/t3code.json" >"$test_tmp/palette.json"
+cp "$test_tmp/palette.json" "$state/theme/t3code.json"
+run_installer || fail "installing with an existing palette succeeds" "$(cat "$test_tmp/output")"
+cmp -s "$test_tmp/palette.json" "$palette" || fail "an existing palette is published without re-staging"
+pass "an existing palette is used without refreshing the current theme"
+
+printf '{"defaultTheme":"dark","keep":"existing settings"}\n' >"$settings"
+cp "$settings" "$test_tmp/settings-before.json"
+if OMARCHY_TEST_T3_FAIL=1 run_installer; then
+  fail "a failed T3 theme selection fails the installer"
+fi
+grep -q 'T3 theme selection failed' "$test_tmp/output" || fail "the CLI failure is visible"
+if grep -Eq 'Opening T3 Code|T3 Code has been installed' "$test_tmp/output"; then
+  fail "a failed selection does not report successful setup"
+fi
+cmp -s "$test_tmp/settings-before.json" "$settings" || fail "a failed selection does not rewrite settings"
+pass "a CLI failure remains visible and leaves the existing settings intact"