feat(scripts): add post-rebuild-check for the gaps a reinstall leaves

A rebuilt machine looks finished and isn't. Five gaps surfaced on velox within two days of its reinstall. Three looked fine on inspection: a stowed unit file, an enabled-looking timer, a present git clone. The script runs those five checks and prints a line for each whether or not it finds anything.

Every probe fails closed. A check that cannot run reports a finding rather than a pass, which matters more here than anywhere: a silent no-op in the checker is the exact failure it exists to catch. `systemctl --user` exits 1 with empty output when there is no user bus, so reading that as "no failed units" would call a machine healthy at the moment nothing was checked. Calls are bounded for the same reason. A check that hangs reports nothing at all, and the machine most in need of checking is the one it hangs on.

I suppressed three classes of finding, each because the live run produced them and reality disagreed. A timer-activated service is supposed to sit linked and not enabled. One expected tooling file is seed-only, so most projects legitimately never have one. Vendored package trees ship their own example files. Left in, those were 19 of the first run's 27 findings, and a check nobody reads is a check that isn't run.

The post-install checklist points at it, and 58 tests cover it.

1 files changed, 407 insertions, 0 deletions

diff --git a/scripts/post-rebuild-check b/scripts/post-rebuild-check
new file mode 100755
index 0000000..8807f85
--- /dev/null
+++ b/scripts/post-rebuild-check
@@ -0,0 +1,407 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-3.0-or-later
+# post-rebuild-check - the five checks a rebuilt machine actually needs.
+#
+# A rebuilt machine looks finished and isn't. Five gaps surfaced on velox
+# within two days of the 2026-08-13 reinstall, and three of them LOOKED
+# fine: a stowed unit file, an enabled timer, a present git clone. Each
+# check below is cheap and turns a silent no-op into a visible line:
+#
+#   1. failed systemd units, user and system scope (calendar-sync failed
+#      every 15 minutes for two days with nobody watching)
+#   2. user unit files present but not enabled (roam-sync and
+#      signal-receive came back linked and inert -- a unit file being
+#      present is not the same as running)
+#   3. tracked *.example files whose real sibling is missing (three
+#      *.local.el were gone on velox; the .example survives in git,
+#      the real file never does)
+#   4. gitignore-mode projects missing tooling paths their own .gitignore
+#      names (a reinstall drops every such project's untracked working
+#      state -- 374 files in .emacs.d's case -- and nothing carries it)
+#   5. signal-cli holds no registered account (velox lost its
+#      registration, and because agent-text relays into this machine,
+#      that silently broke paging for the WHOLE fleet)
+#
+# The .gitignore rule in check 4 is what scopes it: a tooling path is only
+# expected where the project's own .gitignore names it, so a project that
+# never had a todo.org never flags. The ignore file is the project's own
+# record of what it is supposed to hold untracked.
+#
+# EVERY PROBE FAILS CLOSED. A check that cannot run reports a finding, never
+# a pass. This matters more here than anywhere else in the script: the whole
+# point is catching silent no-ops, so a silent no-op in the checker would be
+# the worst possible defect. `systemctl --user` exits 1 with empty output
+# when there is no user bus -- over ssh, from cron, under sudo, on a TTY
+# before the graphical session starts -- and reading that as "no failed
+# units" would report a machine as healthy exactly when nothing was checked.
+#
+# Exit 0 when every check is clean, 1 when any check found something,
+# 2 on usage error.
+#
+# Test seams (env; for each, set-but-empty means "the probe ran and found
+# nothing", unset means "run the real probe"):
+#   PRC_FAILED_UNITS      newline list of "scope:unit" (scope user|system)
+#   PRC_UNIT_STATES       newline list of "unit-file state" replacing the
+#                         user-unit-dir enumeration + is-enabled calls
+#   PRC_LOCAL_SCAN_ROOTS  NEWLINE-separated roots for the *.example scan
+#                         (default: ~/.emacs.d ~/.dotfiles)
+#   PRC_PROJECT_ROOTS     NEWLINE-separated project dirs for check 4
+#                         (default: ~/code/* ~/projects/* ~/.emacs.d
+#                         ~/.dotfiles)
+#   PRC_SIGNAL_ACCOUNTS   signal-cli listAccounts output; "" = no account,
+#                         the special value MISSING = binary absent
+#   PRC_SYSTEMCTL         path to the systemctl binary (a fake, under test)
+#   PRC_SYSTEMCTL_TIMEOUT seconds to allow each systemctl call (default 5)
+#
+# Roots are newline-separated, not space-separated, because a POSIX
+# `for root in $var` splits on spaces and turns one real directory into
+# several imaginary missing ones.
+
+usage() {
+    cat <<'EOF'
+post-rebuild-check - verify a rebuilt machine is actually finished
+
+Runs the five checks that caught velox's 2026-08 reinstall gaps: failed
+units, present-but-inert user units, orphaned *.example configs, missing
+per-project tooling state, and the signal-cli registration.
+
+Usage: post-rebuild-check [--help]
+
+Exit 0 when every check is clean, 1 when any check found something.
+Every probe fails closed: a check that cannot run is a finding, not a pass.
+EOF
+}
+
+case "${1:-}" in
+    --help|-h) usage; exit 0 ;;
+    "") ;;
+    *) echo "post-rebuild-check: unknown argument: $1" >&2; usage >&2; exit 2 ;;
+esac
+
+# Own the internal flags rather than inheriting them, so a caller's unrelated
+# variable of the same name cannot manufacture or mask a finding.
+TOTAL_FINDINGS=0
+CHECK_FINDINGS=0
+FINDING_LINES=""
+signal_missing=""
+
+# Every systemctl call is bounded. A wedged user manager spins and answers
+# nothing -- seen live on velox 2026-08-17, where `is-enabled`, `cat`, and
+# `list-unit-files` all hung while `list-units` still returned. Unbounded, this
+# script would hang on the first unit and never reach the remaining checks,
+# which is a worse failure than reporting nothing: a check that hangs is its
+# own outage, and the machine most in need of checking is the one it hangs on.
+# A timeout yields empty output and a non-zero status, and both are already
+# handled as findings, so bounding the call is all that is needed to fail closed.
+SCTL_TIMEOUT=${PRC_SYSTEMCTL_TIMEOUT:-5}
+SYSTEMCTL=${PRC_SYSTEMCTL:-systemctl}
+
+sctl() {
+    if command -v timeout >/dev/null 2>&1; then
+        timeout "$SCTL_TIMEOUT" "$SYSTEMCTL" "$@"
+    else
+        # Say so rather than dropping the bound silently: without timeout a
+        # wedged manager hangs this run indefinitely, and the whole point of
+        # the bound is that a check which hangs reports nothing at all.
+        [ -n "${sctl_unbounded_warned:-}" ] || {
+            echo "post-rebuild-check: timeout(1) not found — systemctl calls are UNBOUNDED and may hang" >&2
+            sctl_unbounded_warned=1
+        }
+        "$SYSTEMCTL" "$@"
+    fi
+}
+
+WORK=${TMPDIR:-/tmp}/.post-rebuild-check.$$
+if ! mkdir "$WORK" 2>/dev/null; then
+    # Every check stages its input through a file in here. Without it each
+    # loop would read nothing and every check would come back clean, which is
+    # the one failure this script must never produce.
+    echo "post-rebuild-check: cannot create a work directory under ${TMPDIR:-/tmp}" >&2
+    echo "  nothing was checked; this is not a pass" >&2
+    exit 1
+fi
+trap 'rm -rf "$WORK"' EXIT HUP INT TERM
+
+STAGE="$WORK/stage"
+
+finding() {
+    CHECK_FINDINGS=$((CHECK_FINDINGS + 1))
+    TOTAL_FINDINGS=$((TOTAL_FINDINGS + 1))
+    FINDING_LINES="${FINDING_LINES}  DEVIATION: $1
+"
+}
+
+# Print the check's one visible line, then its findings. The visible line
+# is the point: a silent no-op is exactly what let the gaps sit unseen.
+report() {
+    if [ "$CHECK_FINDINGS" -eq 0 ]; then
+        echo "$1 — ok"
+    else
+        echo "$1 — $CHECK_FINDINGS finding(s)"
+        printf '%s' "$FINDING_LINES"
+    fi
+    CHECK_FINDINGS=0
+    FINDING_LINES=""
+}
+
+# Stage a value into $STAGE for the read loops. A failed write is fatal for
+# the same reason a missing work directory is.
+stage() {
+    if ! printf '%s\n' "$1" > "$STAGE" 2>/dev/null; then
+        echo "post-rebuild-check: cannot write $STAGE" >&2
+        echo "  nothing was checked; this is not a pass" >&2
+        exit 1
+    fi
+}
+
+# --- 1. failed units ------------------------------------------------------
+
+if [ -n "${PRC_FAILED_UNITS+set}" ]; then
+    failed=$PRC_FAILED_UNITS
+else
+    failed=""
+    if user_out=$(sctl --user list-units --state=failed --no-legend --plain 2>/dev/null); then
+        failed=$(printf '%s' "$user_out" | awk 'NF {print "user:"$1}')
+    else
+        finding "could not query user units (no user bus?) — nothing was checked in this scope"
+    fi
+    if sys_out=$(sctl list-units --state=failed --no-legend --plain 2>/dev/null); then
+        failed="$failed
+$(printf '%s' "$sys_out" | awk 'NF {print "system:"$1}')"
+    else
+        finding "could not query system units — nothing was checked in this scope"
+    fi
+fi
+stage "$failed"
+while IFS= read -r line; do
+    [ -n "$line" ] || continue
+    scope=${line%%:*}
+    unit=${line#*:}
+    finding "$scope unit failed: $unit"
+done < "$STAGE"
+report "check 1/5: failed units"
+
+# --- 2. user unit files present but not enabled ---------------------------
+
+if [ -n "${PRC_UNIT_STATES+set}" ]; then
+    states=$PRC_UNIT_STATES
+else
+    states=""
+    unit_dir="${XDG_CONFIG_HOME:-$HOME/.config}/systemd/user"
+    if [ ! -d "$unit_dir" ]; then
+        finding "no user unit directory at $unit_dir — nothing was checked"
+    else
+        for f in "$unit_dir"/*.timer "$unit_dir"/*.service; do
+            # -L as well as -e: a stow symlink whose target moved in the
+            # rebuild is exactly the "looked fine" case this check is for,
+            # and -e is false for a broken link.
+            [ -e "$f" ] || [ -L "$f" ] || continue
+            name=$(basename "$f")
+            # A link with nothing behind it is its own finding, decided on the
+            # filesystem rather than from systemd. `is-enabled` calls a
+            # dangling link "not-found" -- the same answer it gives for a unit
+            # that was never installed -- so routing this through the state
+            # table below would drop it silently.
+            if [ -L "$f" ] && [ ! -e "$f" ]; then
+                finding "stowed unit file points at a missing target: $name"
+                continue
+            fi
+            # is-enabled exits non-zero AND prints a state for disabled and
+            # linked, so the exit code cannot distinguish "this unit is
+            # disabled" from "the query failed". The output can: a real answer
+            # is always a word. Empty means no answer, which is a finding
+            # rather than a silent skip -- with no user bus (ssh, cron, sudo,
+            # a TTY before the graphical session) every unit answers empty,
+            # and treating that as unknown-so-ignore would pass the machine
+            # while reading nothing at all.
+            #
+            # No separate bus probe: `is-system-running` and
+            # `show-environment` both block here, and a check that can hang is
+            # its own outage.
+            state=$(sctl --user is-enabled "$name" 2>/dev/null)
+            if [ -z "$state" ]; then
+                finding "could not read the enablement state of $name — it was not checked"
+                continue
+            fi
+            states="${states}${name} ${state}
+"
+        done
+    fi
+fi
+stage "$states"
+# A second copy for the sibling-timer lookup below, so the awk that reads it
+# is never the same open file as the loop reading it.
+cp "$STAGE" "$WORK/states" 2>/dev/null || {
+    echo "post-rebuild-check: cannot write $WORK/states" >&2
+    echo "  nothing was checked; this is not a pass" >&2; exit 1; }
+while read -r name state; do
+    [ -n "$name" ] || continue
+    case "$state" in
+        disabled|linked) ;;
+        *) continue ;;
+    esac
+    # A timer-activated service is SUPPOSED to sit linked-and-not-enabled:
+    # the timer owns activation, and enabling the service as well would run
+    # it at boot on top of its schedule. So a service is suppressed only when
+    # its sibling timer can actually start it (enabled), or when the timer is
+    # itself inert and therefore the finding already -- reporting both would
+    # name one gap twice. A masked, static, or not-found timer starts
+    # nothing, so the service beneath it is as dead as one with no timer.
+    case "$name" in
+        *.service)
+            timer="${name%.service}.timer"
+            tstate=$(awk -v t="$timer" '$1 == t {print $2; exit}' "$WORK/states")
+            # enabled-runtime (enabled until reboot) and generated (something
+            # produced and installed it) are live activation paths, so the
+            # service under one is being started and is not a finding.
+            # disabled and linked suppress for a different reason: the timer
+            # is then the finding itself, reported in its own right.
+            #
+            # "indirect" deliberately does NOT suppress. It means the unit
+            # file itself is not enabled, only that some Also= relative might
+            # be, so nothing here is known to start the service. The
+            # fail-closed rule says the uncertain case flags.
+            case "$tstate" in
+                enabled|enabled-runtime|generated) continue ;;
+                disabled|linked) continue ;;
+            esac
+            ;;
+    esac
+    finding "unit file present but not enabled: $name ($state)"
+done < "$STAGE"
+report "check 2/5: unit files"
+
+# --- 3. *.example files whose real sibling is missing ---------------------
+
+if [ -n "${PRC_LOCAL_SCAN_ROOTS+set}" ]; then
+    scan_roots=$PRC_LOCAL_SCAN_ROOTS
+else
+    scan_roots="$HOME/.emacs.d
+$HOME/.dotfiles"
+fi
+printf '%s\n' "$scan_roots" > "$WORK/roots" 2>/dev/null || {
+    echo "post-rebuild-check: cannot write $WORK/roots" >&2; exit 1; }
+while IFS= read -r root; do
+    [ -n "$root" ] || continue
+    if [ ! -d "$root" ]; then
+        finding "scan root missing: $root"
+        continue
+    fi
+    # Vendored package trees ship their own .example docs; those belong to
+    # the package, not to this machine, so they are noise in front of the
+    # real findings this check exists for.
+    #
+    # -prune, not -not -path: the latter filters find's OUTPUT while still
+    # descending, so an unreadable directory inside a tree we deliberately
+    # ignore would set find's exit status and be reported as an unscanned
+    # part of the root. Pruning means those trees are never entered, so the
+    # exit status only reflects places this check actually wanted to read.
+    #
+    # That status matters: find exits non-zero when it cannot descend
+    # somewhere, having printed only what it could reach. Discarding it would
+    # hide every orphan under an unreadable directory behind a clean "ok",
+    # which is the defect this script exists to catch.
+    if ! find "$root" \
+         \( -name .git -o -name elpa -o -name straight \
+            -o -name node_modules -o -name .venv \) -prune \
+         -o -name '*.example' -print > "$WORK/examples" 2>/dev/null; then
+        finding "could not fully scan $root — part of it was not checked"
+    fi
+    while IFS= read -r ex; do
+        [ -n "$ex" ] || continue
+        # -e, so a sibling that exists only as a dangling symlink counts as
+        # missing. It is not a config the machine can read.
+        [ -e "${ex%.example}" ] || finding "example without its real file: $ex"
+    done < "$WORK/examples"
+done < "$WORK/roots"
+report "check 3/5: local files"
+
+# --- 4. gitignore-mode projects missing their tooling ---------------------
+
+if [ -n "${PRC_PROJECT_ROOTS+set}" ]; then
+    projects=$PRC_PROJECT_ROOTS
+else
+    projects=$(ls -d "$HOME"/code/*/ "$HOME"/projects/*/ 2>/dev/null; \
+               printf '%s\n%s\n' "$HOME/.emacs.d" "$HOME/.dotfiles")
+fi
+printf '%s\n' "$projects" > "$WORK/projects" 2>/dev/null || {
+    echo "post-rebuild-check: cannot write $WORK/projects" >&2; exit 1; }
+# CLAUDE.md is deliberately absent from this set. It is seed-only --
+# install-lang writes it once and the project owns it afterward -- so most
+# projects legitimately never have one, and ratio shows the identical
+# absences in the identical projects. That match is what proves it is the
+# steady state rather than reinstall drift, and flagging it would put nine
+# standing findings in front of every real one.
+#
+# The list is fed to the inner loop straight from a heredoc rather than
+# staged through a file. It is a constant, so a file bought nothing and cost
+# a fifth unguarded write: had it failed (a full tmpfs, say) the inner loop
+# would read nothing and every project would pass silently, which is the one
+# outcome this script must never produce. The heredoc is the inner loop's own
+# stdin and leaves the outer loop's redirect alone.
+while IFS= read -r proj; do
+    [ -n "$proj" ] || continue
+    proj=${proj%/}
+    # -e not -d: in a worktree or submodule .git is a file naming the real
+    # gitdir, and a -d test would skip those projects silently.
+    [ -e "$proj/.git" ] || continue
+    [ -f "$proj/.gitignore" ] || continue
+    while read -r disk pattern; do
+        # Both the anchored (/.ai/) and unanchored (.ai/) ignore styles exist
+        # across the fleet; the sweep-gitignore audit hit exactly that split.
+        #
+        # grep exits 1 for no-match and 2 for an error, so the two are told
+        # apart rather than both read as "the ignore file does not name this".
+        # An unreadable .gitignore would otherwise pass the whole project.
+        grep -Eq "^/?${pattern}/?\$" "$proj/.gitignore" 2>/dev/null
+        case $? in
+            0) [ -e "$proj/$disk" ] \
+                   || finding "$proj: .gitignore names $disk but it is missing on disk" ;;
+            1) ;;
+            *) finding "$proj: could not read .gitignore — the project was not checked"
+               break ;;
+        esac
+    done <<'EOF'
+.ai \.ai
+.claude \.claude
+todo.org todo\.org
+inbox inbox
+EOF
+done < "$WORK/projects"
+report "check 4/5: project tooling"
+
+# --- 5. signal-cli registration -------------------------------------------
+
+if [ -n "${PRC_SIGNAL_ACCOUNTS+set}" ]; then
+    accounts=$PRC_SIGNAL_ACCOUNTS
+    if [ "$accounts" = "MISSING" ]; then
+        accounts=""
+        signal_missing=1
+    fi
+else
+    if command -v signal-cli >/dev/null 2>&1; then
+        if ! accounts=$(signal-cli listAccounts 2>/dev/null); then
+            accounts=""
+            finding "signal-cli listAccounts failed — the registration was not checked"
+            signal_missing=skip
+        fi
+    else
+        accounts=""
+        signal_missing=1
+    fi
+fi
+if [ "$signal_missing" = 1 ]; then
+    finding "signal-cli is not installed — paging relies on it fleet-wide"
+elif [ -z "$signal_missing" ] && [ -z "$accounts" ]; then
+    finding "no signal account registered — agent-text relays into this machine, so paging breaks for the whole fleet"
+fi
+report "check 5/5: signal registration"
+
+# --- summary --------------------------------------------------------------
+
+if [ "$TOTAL_FINDINGS" -eq 0 ]; then
+    echo "all checks clean"
+    exit 0
+fi
+echo "$TOTAL_FINDINGS finding(s) across 5 checks"
+exit 1