diff --git a/regress/options-array.sh b/regress/options-array.sh
new file mode 100644
index 000000000..3b18ce977
--- /dev/null
+++ b/regress/options-array.sh
@@ -0,0 +1,161 @@
+#!/bin/sh
+
+# Tests of array options in the options engine (options_array_* in options.c
+# and the array handling in cmd-set-option.c / cmd-show-options.c).
+#
+# Array options are indexed by integer.  This exercises: setting a whole array
+# from a separator-delimited string; per-index set with option[N]; -a append
+# (which lands at the next free index); show ordering by ascending index and
+# preservation of gaps; per-index unset with -u; show -v of a single index and
+# of a missing index; and per-option separators (user-keys splits only on
+# comma, update-environment on space or comma).
+#
+# update-environment (session), status-format (session), user-keys (server)
+# and command-alias (server) are used as representative array options.
+#
+# options-scope.sh covers scoping/inheritance and options-values.sh covers
+# value validation.
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -Ltest -f/dev/null"
+$TMUX kill-server 2>/dev/null
+
+check_value()
+{
+	out=$($TMUX show $1 2>&1)
+	if [ "$out" != "$2" ]; then
+		echo "show $1 failed."
+		echo "Expected: '$2'"
+		echo "But got:  '$out'"
+		exit 1
+	fi
+}
+
+# check_array $args $expected
+#
+# Compare the full (multi-line) show output for an array option with a
+# newline-separated $expected string.
+check_array()
+{
+	out=$($TMUX show $1 2>&1)
+	if [ "$out" != "$(printf '%s' "$2")" ]; then
+		echo "show $1 (array) failed."
+		echo "Expected:"; printf '%s\n' "$2"
+		echo "But got:"; printf '%s\n' "$out"
+		exit 1
+	fi
+}
+
+check_ok()
+{
+	if ! $TMUX "$@"; then
+		echo "Command failed (expected success): $*"
+		exit 1
+	fi
+}
+
+check_fail()
+{
+	exp="$1"
+	shift
+	out=$($TMUX "$@" 2>&1)
+	if [ $? -eq 0 ]; then
+		echo "Command succeeded (expected failure): $*"
+		exit 1
+	fi
+	if [ "$out" != "$exp" ]; then
+		echo "Wrong error for: $*"
+		echo "Expected: '$exp'"
+		echo "But got:  '$out'"
+		exit 1
+	fi
+}
+
+assert_alive()
+{
+	if [ "$($TMUX display-message -p alive)" != "alive" ]; then
+		echo "Server died: $1"
+		exit 1
+	fi
+}
+
+$TMUX new-session -d -s main -x 80 -y 24 || exit 1
+
+# --- whole-array assignment splits on the separator -----------------------
+#
+# update-environment has the default " ," separator, so a single string value
+# is split into consecutive indices starting at 0.
+check_ok set -g update-environment "AAA BBB,CCC"
+check_array "-g update-environment" "update-environment[0] AAA
+update-environment[1] BBB
+update-environment[2] CCC"
+
+# --- -a append goes to the next free index --------------------------------
+check_ok set -ga update-environment "DDD"
+check_array "-g update-environment" "update-environment[0] AAA
+update-environment[1] BBB
+update-environment[2] CCC
+update-environment[3] DDD"
+
+# --- per-index unset leaves a gap; show preserves order and gaps ----------
+check_ok set -gu update-environment[1]
+check_array "-g update-environment" "update-environment[0] AAA
+update-environment[2] CCC
+update-environment[3] DDD"
+# show -v of an existing index returns its value; a missing index is empty.
+check_value "-gv update-environment[0]" "AAA"
+check_value "-gv update-environment[1]" ""
+
+# --- explicit indexed set, including out-of-order and gaps ----------------
+#
+# status-format is a session array; assigning an empty string first clears its
+# multi-index default, then set specific indices out of order and confirm show
+# sorts by ascending index and keeps the gap at [1].
+check_ok set -g status-format ""
+check_array "-g status-format" "status-format"
+check_ok set -g status-format[5] "five"
+check_ok set -g status-format[0] "zero"
+check_ok set -g status-format[2] "two"
+check_array "-g status-format" "status-format[0] zero
+status-format[2] two
+status-format[5] five"
+
+# --- comma-only separator (user-keys) -------------------------------------
+#
+# user-keys splits only on comma, so an embedded space stays within one entry
+# (and show quotes a value containing a space).
+check_ok set -g user-keys "One,Two Three"
+check_array "-g user-keys" 'user-keys[0] One
+user-keys[1] "Two Three"'
+
+# --- command-type array (a hook) ------------------------------------------
+#
+# Hooks are command arrays: an indexed value is parsed as a command when set
+# and re-printed from the parsed command list; a syntax error is reported.
+check_ok set -g alert-bell[0] "display-message hi"
+check_value "-gv alert-bell[0]" "display-message hi"
+check_fail "syntax error" set -g alert-bell[0] "if -x {"
+
+# --- colour-type array ----------------------------------------------------
+#
+# pane-colours is a colour array; an indexed value is validated as a colour.
+check_ok set -w pane-colours[0] red
+check_value "-wv pane-colours[0]" "red"
+check_fail "bad colour: xxxyyy" set -w pane-colours[1] xxxyyy
+
+# --- -o refuses to overwrite an already-set index -------------------------
+check_ok set -g command-alias[9] "x=list-keys"
+check_fail "already set: command-alias[9]" set -go command-alias[9] "y=list-keys"
+
+# --- non-array option rejects index syntax --------------------------------
+#
+# status-left is a plain string; indexing it is an error.
+check_fail "not an array: status-left[0]" set -g status-left[0] "x"
+
+assert_alive "after options-array tests"
+
+$TMUX kill-server 2>/dev/null
+exit 0
diff --git a/regress/options-scope.sh b/regress/options-scope.sh
new file mode 100644
index 000000000..bbc7168aa
--- /dev/null
+++ b/regress/options-scope.sh
@@ -0,0 +1,208 @@
+#!/bin/sh
+
+# Tests of the options engine scoping and inheritance, as described in the
+# OPTIONS section of tmux(1) and implemented in options.c, cmd-set-option.c and
+# cmd-show-options.c.
+#
+# This exercises: global vs session vs window vs pane precedence; -u to remove
+# an option (revealing the inherited value); -gu to restore a global option to
+# its compiled default; scope inference from the option name (-w/-p and the
+# set-window-option alias); show -v (which does NOT walk parents) versus show -A
+# (which does, marking inherited values with a trailing *); unknown/ambiguous
+# option errors and -q suppression; and user options (@foo) at every scope.
+#
+# options-values.sh covers value validation and options-array.sh covers arrays.
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -Ltest -f/dev/null"
+$TMUX kill-server 2>/dev/null
+
+# check_value $args $expected
+#
+# Run show-option with $args and compare the single-line output with $expected.
+check_value()
+{
+	out=$($TMUX show $1 2>&1)
+	if [ "$out" != "$2" ]; then
+		echo "show $1 failed."
+		echo "Expected: '$2'"
+		echo "But got:  '$out'"
+		exit 1
+	fi
+}
+
+# check_ok $cmd...
+#
+# Run a command and require that it succeeds.
+check_ok()
+{
+	if ! $TMUX "$@"; then
+		echo "Command failed (expected success): $*"
+		exit 1
+	fi
+}
+
+# check_fail $expected_error $cmd...
+#
+# Run a command and require that it fails with the given error message.
+check_fail()
+{
+	exp="$1"
+	shift
+	out=$($TMUX "$@" 2>&1)
+	if [ $? -eq 0 ]; then
+		echo "Command succeeded (expected failure): $*"
+		exit 1
+	fi
+	if [ "$out" != "$exp" ]; then
+		echo "Wrong error for: $*"
+		echo "Expected: '$exp'"
+		echo "But got:  '$out'"
+		exit 1
+	fi
+}
+
+assert_alive()
+{
+	if [ "$($TMUX display-message -p alive)" != "alive" ]; then
+		echo "Server died: $1"
+		exit 1
+	fi
+}
+
+$TMUX new-session -d -s main -x 80 -y 24 || exit 1
+
+# --- global vs session precedence -----------------------------------------
+#
+# status-left is a session option.  A value set at the session scope shadows
+# the global one; show -v at each scope reports that scope's own value.
+check_ok set -g status-left "GLOBAL"
+check_ok set status-left "SESSION"
+check_value "-v status-left" "SESSION"
+check_value "-gv status-left" "GLOBAL"
+
+# show -v does NOT inherit: -u removes the session entry, after which the
+# session-scope show -v is empty even though the global value still exists.
+check_ok set -u status-left
+check_value "-v status-left" ""
+check_value "-gv status-left" "GLOBAL"
+
+# show -A walks the parent scopes and marks an inherited value with a "*".
+out=$($TMUX show -A 2>/dev/null | grep '^status-left\*')
+if [ "$out" != "status-left* GLOBAL" ]; then
+	echo "show -A did not mark inherited status-left."
+	echo "But got:  '$out'"
+	exit 1
+fi
+
+# --- -gu restores the compiled default ------------------------------------
+#
+# Removing a global option with -u restores its built-in default rather than
+# deleting it; status-left's default is the format "[#{session_name}] ".
+check_ok set -g status-left "GLOBAL2"
+check_value "-gv status-left" "GLOBAL2"
+check_ok set -gu status-left
+check_value "-gv status-left" "[#{session_name}] "
+
+# --- scope inference from the option name ---------------------------------
+#
+# mode-keys is a window option, so a bare set-option infers the window scope;
+# set-window-option (setw) is an explicit alias for the same thing, and -g w
+# targets the global window options.
+check_ok set mode-keys vi
+check_value "-wv mode-keys" "vi"
+check_ok setw mode-keys emacs
+check_value "-wv mode-keys" "emacs"
+check_ok set -gw mode-keys vi
+check_value "-gwv mode-keys" "vi"
+
+# cursor-colour is a window-and-pane option.  A pane-scope value overrides a
+# window-scope one for that pane.
+check_ok set -w cursor-colour blue
+check_ok set -p cursor-colour red
+check_value "-pv cursor-colour" "red"
+out=$($TMUX show -Ap 2>/dev/null | grep '^cursor-colour ')
+if [ "$out" != "cursor-colour red" ]; then
+	echo "pane cursor-colour did not override window value."
+	echo "But got:  '$out'"
+	exit 1
+fi
+
+# --- -U unsets a window option and clears pane copies ----------------------
+#
+# When a window option also has per-pane copies, -u on the window scope leaves
+# those pane copies in place; -U additionally removes the option from every
+# pane in the window, so all panes fall back to inheritance.
+$TMUX split-window -t main || exit 1
+panes=$($TMUX list-panes -t main -F '#{pane_id}')
+set -- $panes
+pa=$1
+pb=$2
+check_ok set -p -t "$pa" cursor-colour red
+check_ok set -p -t "$pb" cursor-colour blue
+check_ok set -w -t main cursor-colour green
+check_value "-pv -t $pa cursor-colour" "red"
+check_value "-pv -t $pb cursor-colour" "blue"
+check_value "-wv -t main cursor-colour" "green"
+check_ok set -Uw -t main cursor-colour
+check_value "-pv -t $pa cursor-colour" ""
+check_value "-pv -t $pb cursor-colour" ""
+check_value "-wv -t main cursor-colour" ""
+
+# --- unknown, ambiguous and -q --------------------------------------------
+check_fail "invalid option: no-such-option" set -g no-such-option x
+check_fail "ambiguous option: status-l" set -g status-l x
+# A unique prefix resolves to the full option name.
+check_ok set -g status-inte 5
+check_value "-gv status-interval" "5"
+# -q suppresses the error and exits successfully.
+check_ok set -gq no-such-option x
+check_ok show -gqv no-such-option
+
+# --- errors from unresolvable targets -------------------------------------
+#
+# A -t target that does not resolve produces a scope-specific error from
+# options_scope_from_name()/options_scope_from_flags().
+check_fail "no such session: nosuch" show -t nosuch status-left
+check_fail "no such window: nosuch" show -w -t nosuch mode-keys
+check_fail "no such pane: nosuch" set -p -t nosuch cursor-colour red
+
+# --- show with no option name lists every option --------------------------
+#
+# show without a specific option walks the whole table (cmd_show_options_all).
+# Hooks are hidden unless -H is given.
+$TMUX set -g @listme "here" || exit 1
+if ! $TMUX show -g | grep -q '^@listme here$'; then
+	echo "show -g did not list @listme."
+	exit 1
+fi
+# alert-bell is a hook: only shown with -H.
+if $TMUX show -g | grep -q '^alert-bell'; then
+	echo "show -g listed a hook without -H."
+	exit 1
+fi
+if ! $TMUX show -gH | grep -q '^alert-bell'; then
+	echo "show -gH did not list the alert-bell hook."
+	exit 1
+fi
+
+# --- user options at every scope ------------------------------------------
+#
+# @-prefixed user options can be created freely at any scope and do not
+# inherit type checking.
+check_ok set -g @u "global-user"
+check_ok set @u "session-user"
+check_ok set -w @u "window-user"
+check_ok set -p @u "pane-user"
+check_value "-gv @u" "global-user"
+check_value "-v @u" "session-user"
+check_value "-wv @u" "window-user"
+check_value "-pv @u" "pane-user"
+
+assert_alive "after options-scope tests"
+
+$TMUX kill-server 2>/dev/null
+exit 0
diff --git a/regress/options-values.sh b/regress/options-values.sh
new file mode 100644
index 000000000..28acd2b47
--- /dev/null
+++ b/regress/options-values.sh
@@ -0,0 +1,193 @@
+#!/bin/sh
+
+# Tests of options engine value validation, as implemented by
+# options_from_string() and friends in options.c.
+#
+# Each option table entry has a type (string, number, key, colour, flag,
+# choice, command) with type-specific parsing and validation.  This exercises:
+# number range limits; choice options rejecting unknown values; flag options
+# toggling with no value and rejecting garbage; colour and key options
+# rejecting invalid input; string append with -a; -F expansion at set time;
+# and -o refusing to overwrite an option that is already set.
+#
+# options-scope.sh covers scoping/inheritance and options-array.sh covers
+# arrays.
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -Ltest -f/dev/null"
+$TMUX kill-server 2>/dev/null
+
+check_value()
+{
+	out=$($TMUX show $1 2>&1)
+	if [ "$out" != "$2" ]; then
+		echo "show $1 failed."
+		echo "Expected: '$2'"
+		echo "But got:  '$out'"
+		exit 1
+	fi
+}
+
+check_ok()
+{
+	if ! $TMUX "$@"; then
+		echo "Command failed (expected success): $*"
+		exit 1
+	fi
+}
+
+check_fail()
+{
+	exp="$1"
+	shift
+	out=$($TMUX "$@" 2>&1)
+	if [ $? -eq 0 ]; then
+		echo "Command succeeded (expected failure): $*"
+		exit 1
+	fi
+	if [ "$out" != "$exp" ]; then
+		echo "Wrong error for: $*"
+		echo "Expected: '$exp'"
+		echo "But got:  '$out'"
+		exit 1
+	fi
+}
+
+assert_alive()
+{
+	if [ "$($TMUX display-message -p alive)" != "alive" ]; then
+		echo "Server died: $1"
+		exit 1
+	fi
+}
+
+$TMUX new-session -d -s main -x 80 -y 24 || exit 1
+
+# --- number options -------------------------------------------------------
+#
+# display-time is a number with a minimum of 0; a negative value and a
+# non-numeric value are both rejected via strtonum(3).
+check_ok set -g display-time 4000
+check_value "-gv display-time" "4000"
+check_fail "value is too small: -5" set -g display-time -5
+check_fail "value is invalid: abc" set -g display-time abc
+# A missing value is rejected for a non-flag, non-choice option.
+check_fail "empty value" set -g display-time
+
+# --- choice options -------------------------------------------------------
+#
+# status-keys accepts only its listed choices (vi/emacs); anything else is an
+# "unknown value" error and the option keeps its previous value.
+check_ok set -g status-keys vi
+check_value "-gv status-keys" "vi"
+check_fail "unknown value: bogus" set -g status-keys bogus
+check_value "-gv status-keys" "vi"
+
+# --- flag options ---------------------------------------------------------
+#
+# focus-events is an on/off flag.  Setting with no value toggles it; explicit
+# on/off/yes/no/1/0 are accepted (case-insensitively); anything else fails.
+check_ok set -g focus-events off
+check_value "-gv focus-events" "off"
+check_ok set -g focus-events        # toggle
+check_value "-gv focus-events" "on"
+check_ok set -g focus-events        # toggle back
+check_value "-gv focus-events" "off"
+check_ok set -g focus-events yes
+check_value "-gv focus-events" "on"
+check_ok set -g focus-events NO
+check_value "-gv focus-events" "off"
+check_fail "bad value: maybe" set -g focus-events maybe
+
+# --- colour options -------------------------------------------------------
+#
+# status-bg is a colour; named colours, numbers and #rrggbb are accepted,
+# garbage is rejected.
+check_ok set -g status-bg red
+check_value "-gv status-bg" "red"
+check_ok set -g status-bg colour123
+check_value "-gv status-bg" "colour123"
+check_ok set -g status-bg "#00ff00"
+check_value "-gv status-bg" "#00ff00"
+check_fail "bad colour: xxxyyy" set -g status-bg xxxyyy
+
+# --- style options --------------------------------------------------------
+#
+# status-style is a style string, validated when set; a bogus style keyword is
+# rejected and the old value is retained.
+check_ok set -g status-style "fg=red,bg=black"
+check_value "-gv status-style" "fg=red,bg=black"
+check_fail "invalid style: bg=xxxyyy" set -g status-style "bg=xxxyyy"
+check_value "-gv status-style" "fg=red,bg=black"
+
+# --- key options ----------------------------------------------------------
+#
+# prefix is a key; a valid key name is stored in canonical form, a bad one is
+# rejected.
+check_ok set -g prefix C-a
+check_value "-gv prefix" "C-a"
+check_fail "bad key: boguskey" set -g prefix boguskey
+
+# --- string options with extra validation ---------------------------------
+#
+# default-shell is a string but is checked to be an executable shell; a bogus
+# path is rejected and the old value kept.
+old=$($TMUX show -gv default-shell)
+check_fail "not a suitable shell: /not/a/shell" set -g default-shell /not/a/shell
+check_value "-gv default-shell" "$old"
+
+# --- user options require a value ------------------------------------------
+#
+# A user option set with no value at all is an error.
+check_fail "empty value" set -g @novalue
+
+# --- command options ------------------------------------------------------
+#
+# default-client-command is a command option: the value is parsed as a tmux
+# command when set and re-printed from the parsed command list.  A syntax
+# error is reported and the option is left unchanged.
+check_ok set -g default-client-command "new-window"
+check_value "-gv default-client-command" "new-window"
+check_fail "syntax error" set -g default-client-command "if -x {"
+check_value "-gv default-client-command" "new-window"
+
+# --- renamed option aliases -----------------------------------------------
+#
+# Historical option names are mapped to their current spelling, so setting
+# cursor-color updates cursor-colour.
+check_ok set -w cursor-color red
+check_value "-wv cursor-colour" "red"
+
+# --- string append (-a) ---------------------------------------------------
+#
+# -a appends to the current string value rather than replacing it.
+check_ok set -g @str "foo"
+check_ok set -ga @str "bar"
+check_value "-gv @str" "foobar"
+
+# --- -F expands at set time -----------------------------------------------
+#
+# With -F the value is expanded as a format once, at set time; without -F it is
+# stored literally.
+check_ok set -gF @expanded "#{session_name}"
+check_value "-gv @expanded" "main"
+check_ok set -g @literal "#{session_name}"
+check_value "-gv @literal" "#{session_name}"
+
+# --- -o refuses to overwrite ----------------------------------------------
+#
+# -o makes set-option fail if the option is already set, leaving it unchanged;
+# it succeeds for an option that is not yet set.
+check_ok set -g @once "first"
+check_fail "already set: @once" set -go @once "second"
+check_value "-gv @once" "first"
+check_ok set -go @fresh "value"
+check_value "-gv @fresh" "value"
+
+assert_alive "after options-values tests"
+
+$TMUX kill-server 2>/dev/null
+exit 0