test: check what a real terminal renders for multi, zellij, and the TUI

tests/16-render.sh runs tmux, zellij, and the TUI in xterm on Xvfb,
takes screenshots, and reads them back with tesseract: remote prompts
in all panes, borders and titles with the hosts, [SYNC] appearing and
disappearing, panes side by side, broadcast output in every pane and
input in one pane only without it, windows split by panes_per_window,
the status bar, and TUI marks. Screenshots stay in testenv/.artifacts.

OCR reads three preprocessing variants (plain, stretched for dim gray,
brightest channel for colored text) and normalizes characters that
DejaVu Sans Mono makes ambiguous (1/l, C/().

The screenshots showed tmux cutting the session name in the status bar
to "[netssh-pv"; netssh multi now widens status-left-length for its
own session.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

testenv/tests/16-render.sh

@@ -0,0 +1,75 @@
+# What a user sees: tmux, zellij, and the TUI rendered by a real terminal
+# emulator (xterm on Xvfb), checked by OCR of screenshots. The screenshots stay
+# in testenv/.artifacts/ for a look by eye.
+config <<'EOF'
+resolver:
+  strategies: [management_subnet, primary_ip]
+  management_subnets: [10.231.1.0/24]
+ssh: {default_user: ops}
+groups:
+  pve: ["cluster:pve-fsn1"]
+EOF
+check "refresh" netssh cache refresh
+export TMUX_TMPDIR="$HOME/tmux"
+mkdir -p "$TMUX_TMPDIR" "$HOME/.config/zellij"
+printf 'show_startup_tips false\nshow_release_notes false\n' >"$HOME/.config/zellij/config.kdl"
+start_screen && ok "X server and xterm" || bad "X server and xterm" "Xvfb did not start"
+
+p1=fsn/fsn1-pve1.hoster.test p2=fsn/fsn1-pve2.hoster.test p3=fsn/fsn1-pve3.hoster.test
+prompts() { screen_shows "$1" "fsn1-pve1:~\$" "fsn1-pve2:~\$" "fsn1-pve3:~\$"; }
+# Two hosts on one OCR line means their panes sit side by side (tiled grid).
+side_by_side() { screen_text "$1" | ocr_norm | grep -F "$(printf %s "$2" | ocr_norm)" | grep -qF "$(printf %s "$3" | ocr_norm)"; }
+visible() { # NAME SHOT TEXT... — wait until the screen shows every TEXT
+  local name=$1 shot=$2
+  shift 2
+  if wait_for 30 screen_shows "$shot" "$@"; then ok "$name"; else bad "$name" "$(screen_text "$shot")"; fi
+}
+
+# --- tmux, started from a plain terminal: new session, attached in xterm ---
+term netssh multi --sync @pve
+visible "tmux: three remote shells on screen" tmux-1 "fsn1-pve1:~\$" "fsn1-pve2:~\$" "fsn1-pve3:~\$"
+visible "tmux: borders show host and [SYNC]" tmux-1 "$p1 [SYNC]" "$p2 [SYNC]" "$p3 [SYNC]"
+side_by_side tmux-1 "$p1" "$p2" && ok "tmux: tiled, first two panes side by side" || bad "tmux: tiled, first two panes side by side" "$(screen_text tmux-1)"
+tmux send-keys -t netssh-pve "echo typed-once-\$(hostname)" Enter
+visible "tmux: broadcast output in every pane" tmux-2 "typed-once-fsn1-pve1" "typed-once-fsn1-pve2" "typed-once-fsn1-pve3"
+tmux set-window-option -t netssh-pve synchronize-panes off
+tmux send-keys -t netssh-pve "echo just-this-pane" Enter
+sleep 1
+shot tmux-3
+[ "$(screen_count tmux-3 "just-this-pane")" = 2 ] && ok "tmux: without broadcast only one pane gets input" || bad "tmux: without broadcast only one pane gets input" "$(screen_text tmux-3)"
+shows_sync() { screen_shows tmux-3 "[SYNC]"; }
+shows_sync && bad "tmux: [SYNC] disappears when broadcast is off" "$(screen_text tmux-3)" || ok "tmux: [SYNC] disappears when broadcast is off"
+tmux kill-server
+
+# --- more hosts than panes_per_window: further windows ---
+sed -i 's/^groups:/multi: {panes_per_window: 2}\ngroups:/' "$XDG_CONFIG_HOME/netssh.yaml"
+term netssh multi @pve
+visible "tmux: hosts split over windows pve-1 and pve-2" tmux-windows "pve-1" "pve-2"
+visible "tmux: status bar shows the whole session name" tmux-windows "[netssh-pve]"
+tmux kill-server
+sed -i '/^multi: {panes_per_window: 2}$/d' "$XDG_CONFIG_HOME/netssh.yaml"
+
+# --- zellij: generated grid layout, broadcast through the sync tab ---
+term netssh multi --zellij @pve
+visible "zellij: three remote shells on screen" zellij-1 "fsn1-pve1:~\$" "fsn1-pve2:~\$" "fsn1-pve3:~\$"
+visible "zellij: pane titles show the hosts" zellij-1 "$p1" "$p2" "$p3"
+side_by_side zellij-1 "$p1" "$p2" && ok "zellij: grid, first two panes side by side" || bad "zellij: grid, first two panes side by side" "$(screen_text zellij-1)"
+session=$(zellij list-sessions --short --no-formatting 2>/dev/null | head -1)
+zellij --session "$session" action toggle-active-sync-tab
+zellij --session "$session" action write-chars 'echo zellij-$(hostname)'
+zellij --session "$session" action write 13
+visible "zellij: broadcast output in every pane" zellij-2 "zellij-fsn1-pve1" "zellij-fsn1-pve2" "zellij-fsn1-pve3"
+zellij kill-all-sessions --yes >/dev/null 2>&1
+
+# --- TUI: mark hosts, open them together ---
+term tmux new-session -s tui netssh
+visible "TUI: search screen" tui-1 "Search hostname"
+tmux send-keys -t tui "pve"
+visible "TUI: results listed" tui-2 "$p1" "$p2" "$p3"
+tmux send-keys -t tui C-a
+visible "TUI: all marked" tui-3 "3 marked"
+tmux send-keys -t tui Enter
+visible "TUI: marked hosts open side by side" tui-4 "fsn1-pve1:~\$" "fsn1-pve2:~\$" "fsn1-pve3:~\$"
+tmux kill-server
+
+stop_screen

testenv/tests/lib.sh

@@ -76,3 +76,79 @@ wait_for() {
     sleep 0.2
   done
 }
+
+# --- rendering in a real terminal emulator (tests/16-render.sh) ---
+# Xvfb provides a screen, xterm renders the terminal, `import` takes a
+# screenshot, and tesseract reads it back, so checks see what a user sees.
+
+start_screen() {
+  Xvfb :99 -screen 0 1920x1080x24 -nolisten tcp >/dev/null 2>&1 &
+  XVFB_PID=$!
+  export DISPLAY=:99
+  wait_for 10 import -window root -crop 1x1+0+0 null:
+}
+
+stop_screen() {
+  pkill -u "$(id -u)" xterm 2>/dev/null
+  kill "$XVFB_PID" 2>/dev/null
+  wait "$XVFB_PID" 2>/dev/null
+}
+
+# term CMD... — run CMD in a full-screen xterm (UTF-8, DejaVu Sans Mono).
+term() {
+  pkill -u "$(id -u)" xterm 2>/dev/null
+  xterm -u8 -geometry 190x52+0+0 -fa 'DejaVu Sans Mono' -fs 11 -bg '#1e1e1e' -fg '#d4d4d4' \
+    -T netssh -e "$@" >/dev/null 2>&1 &
+  sleep 1
+}
+
+# shot NAME — screenshot to /artifacts/NAME.png.
+shot() { import -window root "/artifacts/$1.png"; }
+
+# OCR preprocessing variants: no single one reads everything (dim hint lines,
+# red/green borders): plain luminance, stretched dark range for dim gray, and
+# the brightest color channel for colored text.
+OCR_VARIANTS=("-colorspace gray" "-colorspace gray -level 10%,40%"
+  "-channel RGB -separate -evaluate-sequence max -level 10%,60%")
+
+# ocr_variant NAME I — OCR of screenshot NAME with preprocessing variant I.
+ocr_variant() {
+  # shellcheck disable=SC2086
+  magick "/artifacts/$1.png" ${OCR_VARIANTS[$2]} -negate -resize 300% png:- |
+    tesseract stdin stdout --psm 6 2>/dev/null
+}
+
+# screen_text NAME — the text of all variants combined.
+screen_text() {
+  local i
+  for i in "${!OCR_VARIANTS[@]}"; do ocr_variant "$1" "$i"; done
+}
+
+# ocr_norm maps characters OCR confuses in DejaVu Sans Mono (1/l/I/|, C/( , 0/O)
+# to one form; expected text gets the same mapping, so comparisons stay strict
+# about everything else.
+ocr_norm() { tr 'lI|(O' '111C0'; }
+
+# screen_shows NAME TEXT... — take a screenshot and check that OCR finds every TEXT.
+screen_shows() {
+  local name=$1 text want
+  shift
+  shot "$name"
+  text=$(screen_text "$name" | ocr_norm)
+  for want in "$@"; do
+    want=$(printf '%s' "$want" | ocr_norm)
+    [[ $text == *"$want"* ]] || return 1
+  done
+}
+
+# screen_count NAME TEXT — how often TEXT is on screenshot NAME: the highest
+# count of any OCR variant (they read the same screen, so they are not added).
+screen_count() {
+  local want i n max=0
+  want=$(printf '%s' "$2" | ocr_norm)
+  for i in "${!OCR_VARIANTS[@]}"; do
+    n=$(ocr_variant "$1" "$i" | ocr_norm | grep -oF -- "$want" | wc -l)
+    [ "$n" -gt "$max" ] && max=$n
+  done
+  echo "$max"
+}