diff --git a/README.md b/README.md
index 261e362..ee3f112 100644
--- a/README.md
+++ b/README.md
@@ -404,8 +404,9 @@ commands you trust.
 
 Squarebox builds on Omarchy's defaults with one portable rule: `Super` belongs
 to the OS/window manager, while `Ctrl` acts immediately in the focused app.
-Adding `Shift` modifies or moves the target. Herdr follows this language
-directly; its `F12` prefix remains available as a compatibility fallback.
+Herdr uses `Ctrl+Alt` for direct letter chords because many terminals collapse
+`Ctrl+Shift+letter` into the unshifted control key. Its `F12` prefix remains
+available as a compatibility fallback.
 
 Herdr's generated default uses familiar app shortcuts:
 
@@ -415,8 +416,8 @@ Herdr's generated default uses familiar app shortcuts:
 | Cycle / select tabs | `Ctrl+Tab`, `Ctrl+Shift+Tab` / `Ctrl+1-9` |
 | Focus / swap pane | `Ctrl+Arrow` / `Ctrl+Shift+Arrow` |
 | Sidebar / go to | `Ctrl+B` / `Ctrl+G` |
-| Split right / down | `Ctrl+\\` / `Ctrl+Shift+\\` |
-| Zoom / new workspace | `Ctrl+Shift+Z` / `Ctrl+Shift+N` |
+| Split right / down | `Ctrl+\\` / `Ctrl+Alt+\\` |
+| Zoom / new workspace | `Ctrl+Alt+Z` / `Ctrl+Alt+N` |
 | Compatibility prefix | `F12` |
 
 These bindings intentionally take precedence over matching shell or nested-app
diff --git a/setup.sh b/setup.sh
index db89a27..2770b2b 100755
--- a/setup.sh
+++ b/setup.sh
@@ -1788,14 +1788,15 @@ _install_herdr_inner() {
 		agent_panel_sort = "spaces"
 
 		# Super belongs to the OS/window manager. Ctrl acts immediately in Herdr;
-		# Shift modifies or moves. F12 keeps the upstream-style prefix fallbacks.
+		# Ctrl+Alt keeps direct letter chords distinguishable across terminals.
+		# F12 keeps the upstream-style prefix fallbacks.
 		[keys]
 		prefix = "f12"
 		help = ["ctrl+?", "prefix+?"]
 		goto = ["ctrl+g", "prefix+g"]
 		workspace_picker = "prefix+w"
 		toggle_sidebar = ["ctrl+b", "prefix+b"]
-		detach = ["ctrl+shift+q", "prefix+q"]
+		detach = ["ctrl+alt+q", "prefix+q"]
 
 		new_tab = ["ctrl+t", "prefix+c"]
 		previous_tab = ["ctrl+shift+tab", "prefix+p"]
@@ -1804,7 +1805,7 @@ _install_herdr_inner() {
 		rename_tab = "prefix+shift+t"
 		close_tab = "prefix+shift+x"
 
-		new_workspace = ["ctrl+shift+n", "prefix+shift+n"]
+		new_workspace = ["ctrl+alt+n", "prefix+shift+n"]
 		rename_workspace = "prefix+shift+w"
 		close_workspace = "prefix+shift+d"
 
@@ -1819,12 +1820,17 @@ _install_herdr_inner() {
 
 		close_pane = ["ctrl+w", "prefix+x"]
 		split_vertical = ["ctrl+backslash", "prefix+v"]
-		split_horizontal = ["ctrl+shift+backslash", "prefix+minus"]
-		zoom = ["ctrl+shift+z", "prefix+z"]
+		split_horizontal = ["ctrl+alt+backslash", "prefix+minus"]
+		zoom = ["ctrl+alt+z", "prefix+z"]
 		resize_mode = "prefix+r"
-		HERDRCONF
+			HERDRCONF
 			mv -fT -- "$config_tmp" "$config_path" || exit 1
 			config_tmp=""
+			if ! herdr config check >/dev/null 2>&1; then
+				echo "ERROR: Generated Herdr config failed validation: $config_path" >&2
+				rm -f -- "$config_path"
+				exit 1
+			fi
 		); then
 			return 1
 		fi
diff --git a/tests/test-provision-state.sh b/tests/test-provision-state.sh
index 57c710a..d978e1d 100755
--- a/tests/test-provision-state.sh
+++ b/tests/test-provision-state.sh
@@ -258,16 +258,38 @@ rm -f "$ZELLIJ_CONF"
 
 # Herdr uses the shared immediate-app keyboard language for a fresh Managed
 # home, while an existing config remains user-controlled.
-printf '#!/usr/bin/env bash\nexit 0\n' > "$BIN/herdr"
+cat > "$BIN/herdr" <<'EOF'
+#!/usr/bin/env bash
+set -euo pipefail
+if [ "${1:-}" = config ] && [ "${2:-}" = check ]; then
+	config="$HOME/.config/herdr/config.toml"
+	grep -Fqx 'detach = ["ctrl+alt+q", "prefix+q"]' "$config"
+	grep -Fqx 'new_workspace = ["ctrl+alt+n", "prefix+shift+n"]' "$config"
+	grep -Fqx 'split_horizontal = ["ctrl+alt+backslash", "prefix+minus"]' "$config"
+	grep -Fqx 'zoom = ["ctrl+alt+z", "prefix+z"]' "$config"
+	[ "${HERDR_CHECK_FAIL:-0}" -eq 0 ]
+	printf 'config check\n' >> "$HERDR_TEST_LOG"
+fi
+EOF
 chmod +x "$BIN/herdr"
 printf 'herdr\n' > "$STATE/multiplexer"
 rm -rf "$HOME_DIR/.config/herdr"
-HOME="$HOME_DIR" SQUAREBOX_STATE_DIR="$STATE" \
+HERDR_TEST_LOG="$TMP/herdr-check.log" HOME="$HOME_DIR" SQUAREBOX_STATE_DIR="$STATE" \
 	SQUAREBOX_TOOL_LIB="$FIXTURE_LIB" SQUAREBOX_TOOLS_YAML=/dev/null \
 	PATH="$BIN:$PATH" bash "$ROOT/setup.sh" --rerun multiplexers >"$TMP/herdr-fresh.out" 2>"$TMP/herdr-fresh.err"
 HERDR_CONF="$HOME_DIR/.config/herdr/config.toml"
-assert_true "grep -Fqx 'prefix = \"f12\"' '$HERDR_CONF' && grep -Fqx 'new_tab = [\"ctrl+t\", \"prefix+c\"]' '$HERDR_CONF' && grep -Fqx 'focus_pane_left = [\"ctrl+left\", \"prefix+h\"]' '$HERDR_CONF'" \
-	"fresh Herdr config uses immediate Ctrl actions with F12 fallbacks"
+assert_true "grep -Fqx 'config check' '$TMP/herdr-check.log' && grep -Fqx 'prefix = \"f12\"' '$HERDR_CONF' && grep -Fqx 'new_tab = [\"ctrl+t\", \"prefix+c\"]' '$HERDR_CONF' && grep -Fqx 'focus_pane_left = [\"ctrl+left\", \"prefix+h\"]' '$HERDR_CONF'" \
+	"fresh Herdr config passes validation with terminal-safe direct chords and F12 fallbacks"
+rm -f "$HERDR_CONF"
+if HERDR_CHECK_FAIL=1 HERDR_TEST_LOG="$TMP/herdr-check-fail.log" HOME="$HOME_DIR" SQUAREBOX_STATE_DIR="$STATE" \
+	SQUAREBOX_TOOL_LIB="$FIXTURE_LIB" SQUAREBOX_TOOLS_YAML=/dev/null \
+	PATH="$BIN:$PATH" bash "$ROOT/setup.sh" --rerun multiplexers >"$TMP/herdr-invalid.out" 2>"$TMP/herdr-invalid.err"; then
+	HERDR_INVALID_RC=0
+else
+	HERDR_INVALID_RC=$?
+fi
+assert_true "[ \"$HERDR_INVALID_RC\" -ne 0 ] && [ ! -e '$HERDR_CONF' ] && grep -Fq 'Generated Herdr config failed validation' '$TMP/herdr-invalid.err'" \
+	"Herdr setup removes a generated config that fails validation"
 printf '# user-owned Herdr config\n' > "$HERDR_CONF"
 HOME="$HOME_DIR" SQUAREBOX_STATE_DIR="$STATE" \
 	SQUAREBOX_TOOL_LIB="$FIXTURE_LIB" SQUAREBOX_TOOLS_YAML=/dev/null \