workstation: tmux sessions survive devvm reboots (save timer + boot restore)

Viktor: emo's open web-terminal sessions must persist across reboots.
Claude conversations were already durable on disk; the volatile part
was the tmux wiring (which named session runs which conversation).

t3-tmux-sessions save (5-min timer) snapshots every roster user's
sessions to /var/lib/t3-tmux-state/<user>.tsv — conversation uuid
taken from argv --resume (self-sustaining once restored) or the
newest transcript in the cwd-slug project dir created after process
start (fresh launcher sessions; claude does NOT hold its transcript
fd open, so fd-sniffing was a dead end). t3-tmux-sessions restore
(boot oneshot, also safe after partial loss) recreates missing
sessions with claude --resume <uuid>. Reconciler self-heals both
units' enablement.

Verified live: emo's 5 sessions snapshotted with correct uuids;
killed R730-cooling -> restore brought it back resuming the same
conversation (context meter identical); other sessions untouched.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/t3-provision-users.sh

@@ -256,6 +256,11 @@ done < <(jq -r '.ports | to_entries[] | [.key, .value] | @tsv' "$desired_file")
 #     breaking nightly mid-day and took out auth for everyone. `enable` (no --now) just arms
 #     the 04:00 schedule; fresh boxes get t3 from setup-devvm.sh's pinned install, not here.
 run systemctl enable t3-autoupdate.timer >/dev/null 2>&1 || true
+#     tmux session persistence: periodic snapshot + boot-time restore (reboot
+#     survival for users' named claude sessions). Safe to --now: save is a
+#     read-only snapshot; restore is per-session idempotent.
+run systemctl enable --now t3-tmux-save.timer >/dev/null 2>&1 || true
+run systemctl enable t3-tmux-restore.service >/dev/null 2>&1 || true
 
 # 6) regenerate /etc/ttyd-user-map + dispatch.json from the desired state (SSoT:
 #    a roster entry removed here DISAPPEARS, which is what the offboarding cut relies on)

scripts/t3-tmux-restore.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=Restore workstation tmux sessions (resume saved claude conversations) after boot
+After=network.target local-fs.target
+# Before the save timer's first run (OnBootSec=10min) so an empty post-boot
+# state can never be snapshotted over the manifest being restored from.
+
+[Service]
+Type=oneshot
+ExecStart=/usr/local/bin/t3-tmux-sessions restore
+
+[Install]
+WantedBy=multi-user.target

scripts/t3-tmux-save.service

@@ -0,0 +1,6 @@
+[Unit]
+Description=Snapshot workstation tmux sessions (name -> claude conversation) for reboot survival
+
+[Service]
+Type=oneshot
+ExecStart=/usr/local/bin/t3-tmux-sessions save

scripts/t3-tmux-save.timer

@@ -0,0 +1,10 @@
+[Unit]
+Description=Periodic workstation tmux session snapshot
+
+[Timer]
+OnBootSec=10min
+OnCalendar=*:0/5
+Persistent=false
+
+[Install]
+WantedBy=timers.target

scripts/t3-tmux-sessions.sh

@@ -0,0 +1,110 @@
+#!/usr/bin/env bash
+# Persist workstation tmux sessions across devvm reboots.
+#
+#   save    — snapshot every roster user's live tmux sessions to
+#             /var/lib/t3-tmux-state/<user>.tsv (name, cwd, claude session
+#             uuid). The uuid is sniffed from the claude process's OPEN
+#             transcript fd (~/.claude/projects/<slug>/<uuid>.jsonl), so it is
+#             correct regardless of how the session was launched (fresh via
+#             start-claude.sh or an explicit --resume). Runs every 5 min via
+#             t3-tmux-save.timer. A user with no tmux server keeps their last
+#             manifest (so a post-reboot save can't wipe it before restore).
+#   restore — recreate manifest sessions that don't currently exist, resuming
+#             each saved conversation (claude --resume <uuid>). Per-session
+#             idempotent: existing names are left alone, so it is safe both at
+#             boot (t3-tmux-restore.service) and after a partial loss.
+#
+# v1 limitation: one window/pane per session is captured (the workstation
+# usage pattern — one named claude conversation per tmux session).
+set -euo pipefail
+
+STATE_DIR=/var/lib/t3-tmux-state
+MAP=/etc/ttyd-user-map
+MODE="${1:-}"
+
+log() { echo "[t3-tmux-sessions] $*"; }
+
+users() { [[ -r "$MAP" ]] && cut -d= -f2 "$MAP" | sort -u; }
+
+tmux_as() { local u="$1"; shift; runuser -u "$u" -- tmux "$@"; }
+
+# First descendant of $1 whose comm is `claude` (BFS, bounded by process tree).
+claude_pid_under() {
+  local q=("$1") pid kids
+  while ((${#q[@]})); do
+    pid="${q[0]}"; q=("${q[@]:1}")
+    [[ "$(ps -o comm= -p "$pid" 2>/dev/null)" == claude ]] && { echo "$pid"; return 0; }
+    read -ra kids <<<"$(pgrep -P "$pid" 2>/dev/null | tr '\n' ' ')" || true
+    ((${#kids[@]})) && q+=("${kids[@]}")
+  done
+  return 1
+}
+
+# Conversation uuid of a claude process ($1 pid, $2 user, $3 cwd). Two sources
+# (claude does NOT hold its transcript fd open, so fd-sniffing doesn't work):
+#  1. argv `--resume <uuid>` — covers every session this script's restore (or a
+#     manual recovery) created, making the save/restore loop self-sustaining;
+#  2. newest <uuid>.jsonl in the user's cwd-slug project dir created at/after
+#     the process start — covers fresh launcher-started sessions.
+# Always returns 0; empty output means "no conversation" (restored as a shell).
+uuid_of_claude() {
+  local uuid slug dir start f
+  uuid="$(tr '\0' '\n' < "/proc/$1/cmdline" 2>/dev/null \
+          | grep -A1 -x -- '--resume' | tail -1 \
+          | grep -oE '^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$' || true)"
+  [[ -n "$uuid" ]] && { echo "$uuid"; return 0; }
+  slug="${3//\//-}"; slug="${slug//./-}"
+  dir="$(getent passwd "$2" | cut -d: -f6)/.claude/projects/$slug"
+  [[ -d "$dir" ]] || return 0
+  start=$(( $(date +%s) - $(ps -o etimes= -p "$1" 2>/dev/null | tr -d ' ' || echo 0) - 5 ))
+  f="$(find "$dir" -maxdepth 1 -name '*.jsonl' -newermt "@$start" -printf '%T@ %f\n' 2>/dev/null \
+       | sort -rn | head -1 | awk '{print $2}' || true)"
+  [[ -n "$f" ]] && echo "${f%.jsonl}"
+  return 0
+}
+
+save() {
+  install -d -m 0755 "$STATE_DIR"
+  local u uid sess pane_pid pane_cwd cpid uuid tmp
+  for u in $(users); do
+    uid="$(id -u "$u" 2>/dev/null)" || continue
+    [[ -S "/tmp/tmux-$uid/default" ]] || continue   # no server -> keep last manifest
+    tmp="$(mktemp)"
+    while IFS=$'\t' read -r sess pane_pid pane_cwd; do
+      [[ -n "$sess" ]] || continue
+      uuid=""
+      if cpid="$(claude_pid_under "$pane_pid")"; then uuid="$(uuid_of_claude "$cpid" "$u" "$pane_cwd")"; fi
+      printf '%s\t%s\t%s\n' "$sess" "$pane_cwd" "$uuid" >> "$tmp"
+    done < <(tmux_as "$u" list-panes -a -F $'#{session_name}\t#{pane_pid}\t#{pane_current_path}' 2>/dev/null \
+             | sort -u -t$'\t' -k1,1)
+    install -m 0600 "$tmp" "$STATE_DIR/$u.tsv"; rm -f "$tmp"
+    log "saved $(wc -l < "$STATE_DIR/$u.tsv") session(s) for $u"
+  done
+}
+
+restore() {
+  local u f sess cwd uuid cmd
+  for u in $(users); do
+    f="$STATE_DIR/$u.tsv"
+    [[ -s "$f" ]] || continue
+    while IFS=$'\t' read -r sess cwd uuid; do
+      [[ -n "$sess" ]] || continue
+      tmux_as "$u" has-session -t "=$sess" 2>/dev/null && continue   # already live
+      [[ -d "$cwd" ]] || cwd="$(getent passwd "$u" | cut -d: -f6)"
+      if [[ -n "$uuid" ]]; then
+        cmd="claude --dangerously-skip-permissions --resume $uuid --name \"$sess\"; echo; echo '  claude exited — shell preserved'; exec bash -l"
+      else
+        cmd="exec bash -l"
+      fi
+      tmux_as "$u" new-session -d -s "$sess" -c "$cwd" "$cmd" \
+        && log "restored $u:$sess${uuid:+ (resume ${uuid:0:8})}" \
+        || log "WARN: failed to restore $u:$sess"
+    done < "$f"
+  done
+}
+
+case "$MODE" in
+  save) save ;;
+  restore) restore ;;
+  *) echo "usage: t3-tmux-sessions save|restore" >&2; exit 1 ;;
+esac