diff --git a/bin/fm-backend.sh b/bin/fm-backend.sh
index 3233921e071..6e06c590145 100644
--- a/bin/fm-backend.sh
+++ b/bin/fm-backend.sh
@@ -600,6 +600,10 @@ fm_backend_expected_label_of_selector() {  # <raw-target> <state-dir>
 fm_backend_source() {  # <name>
   local name=$1
   fm_backend_validate "$name" || return 1
+  # A missing or unreadable adapter must come back as an ordinary failed
+  # return: on Bash 3.2 a `.` of a missing file can be a fatal shell error that
+  # skips the caller's own refusal; teardown's EXIT guard handles that abort.
+  [ -r "$FM_BACKEND_LIB_DIR/backends/$name.sh" ] || return 1
   case "$name" in
     tmux)
       if [ -z "${_FM_BACKEND_TMUX_SOURCED:-}" ]; then
diff --git a/bin/fm-teardown.sh b/bin/fm-teardown.sh
index cbbad96b468..4dc73ed82f3 100755
--- a/bin/fm-teardown.sh
+++ b/bin/fm-teardown.sh
@@ -19,6 +19,13 @@
 # home with a backlog but no compatible tasks-axi refuses before cleanup.
 # None of this loosens the landed-work gates below: the transition runs only on
 # the paths that already proceed to remove the record.
+# An exit with status zero before this invocation confirms task-record removal
+# is an aborted teardown:
+# the EXIT guard returns failure and reports it on the original stderr, even if
+# the triggering call discarded stderr, without continuing cleanup.
+# Local and remote completion record that removal while holding the meta lock,
+# so replacement metadata published afterward does not cause a false abort.
+# tests/fm-gotmp.test.sh covers this guard and adapter-load failure retention.
 # The close - and only the close - is replaced by `tasks-axi reopen` with the
 # deliverable recorded while the backlog item is still an open captain call
 # (bin/fm-captain-hold.sh `open` owns that predicate), because the policy holds
@@ -75,7 +82,11 @@
 # is the approved discard path that prevalidates child removal targets, locks each
 # descendant home's task set before enumeration, and holds those locks through
 # child cleanup. Contention refuses the complete forced teardown before child
-# mutation. Local and remote retirement serialize their destructive phase with
+# mutation. Required child adapters are loaded recursively before child cleanup;
+# unavailable adapters or fatal source exits preserve parent and child metadata,
+# work, and scratch. After successful loading, endpoint kills keep their existing
+# best-effort behavior and Herdr's exact-pane disappearance requirement.
+# Local and remote retirement serialize their destructive phase with
 # that mate's backlog-handoff lock under the registry lock. Pending handoff wake
 # state is retired with the home, and local removal failure restores that state
 # before preserving the route for retry. Teardown then discards child work, kills
@@ -262,6 +273,7 @@ CONTROL_LOCK="$STATE/.control-$ID.lock"
 CONTROL_LOCK_HELD=0
 META_LOCK=
 META_LOCK_HELD=0
+TEARDOWN_RECORD_REMOVED=0
 DESCENDANT_LOCK_PATHS=()
 DESCENDANT_TASK_STATES=()
 DESCENDANT_TASK_IDS=()
@@ -297,8 +309,15 @@ teardown_release_locks() {
     CONTROL_LOCK_HELD=0
   fi
   fm_lease_guard_release || true
+  # A fatal source error can leave $? at 0 on Bash 3.2, just like an explicit
+  # exit 0. Descriptor 3 survives best-effort callers redirecting their stderr.
+  if [ "$status" -eq 0 ] && [ "$TEARDOWN_RECORD_REMOVED" != 1 ]; then
+    echo "error: teardown of $ID aborted before its task record was removed; every durable record is retained" >&3
+    exit 1
+  fi
   return "$status"
 }
+exec 3>&2
 trap teardown_release_locks EXIT
 fm_lock_try_acquire "$CONTROL_LOCK" || {
   echo "error: another lifecycle action is already running for task $ID; nothing was changed" >&2
@@ -778,6 +797,7 @@ remote_secondmate_teardown() {
   mv -f -- "$tmp" "$SECONDMATE_REG"
   status_retire_presentation_task "$STATE" "$ID" || return 1
   fm_backlog_atomic_transition remove "$STATE/$ID.meta" "task record" "$STATE" || return 1
+  TEARDOWN_RECORD_REMOVED=1
   rm -f -- "$STATE/$ID.turn-ended"
   printf 'teardown %s complete (remote %s:%s)\n' "$ID" "$remote_host" "$remote_home"
   return 0
@@ -2580,7 +2600,7 @@ $session	$lock_path"
   return 1
 }
 
-preflight_firstmate_home_herdr_children() {  # <home>
+preflight_firstmate_home_backend_children() {  # <home>
   local home=$1 sub_state child_meta child_id child_backend child_target child_kind child_home child_wt
   sub_state="$home/state"
   [ -d "$sub_state" ] || return 0
@@ -2592,6 +2612,9 @@ preflight_firstmate_home_herdr_children() {  # <home>
     child_target=$FM_BACKEND_VALIDATED_TARGET
     if [ "$child_backend" = herdr ]; then
       teardown_herdr_preflight_target "$child_target" "$child_id" || return 1
+    elif ! fm_backend_source "$child_backend"; then
+      echo "REFUSED: $child_backend adapter is unavailable for child $child_id; forced teardown changed nothing" >&2
+      return 1
     fi
     child_kind=$(meta_value "$child_meta" kind)
     [ -n "$child_kind" ] || child_kind=ship
@@ -2599,7 +2622,7 @@ preflight_firstmate_home_herdr_children() {  # <home>
       child_wt=$(meta_value "$child_meta" worktree)
       child_home=$(meta_value "$child_meta" home)
       [ -n "$child_home" ] || child_home=$child_wt
-      preflight_firstmate_home_herdr_children "$child_home" || return 1
+      preflight_firstmate_home_backend_children "$child_home" || return 1
     fi
   done
 }
@@ -2732,7 +2755,7 @@ if [ "$KIND" = secondmate ]; then
     if [ "$BACKEND" = herdr ]; then
       teardown_herdr_preflight_target "$T" "$ID" || exit 1
     fi
-    preflight_firstmate_home_herdr_children "$HOME_PATH" || exit 1
+    preflight_firstmate_home_backend_children "$HOME_PATH" || exit 1
   fi
 fi
 
@@ -3135,6 +3158,7 @@ else
     exit 1
   fi
 fi
+TEARDOWN_RECORD_REMOVED=1
 fm_lock_release "$META_LOCK"
 META_LOCK_HELD=0
 if [ "$KIND" != scout ] && [ "$KIND" != secondmate ] && [ "$MODE" != local-only ]; then
diff --git a/tests/fm-gotmp.test.sh b/tests/fm-gotmp.test.sh
index d29c540e648..48f7a12fa1b 100755
--- a/tests/fm-gotmp.test.sh
+++ b/tests/fm-gotmp.test.sh
@@ -44,8 +44,11 @@ TMP_ROOT=$(mktemp -d "${TMPDIR:-/tmp}/fm-gotmp-tests.XXXXXX")
 # state and helper scripts inside it. Stub the helper scripts fm-teardown calls so no
 # live tmux/treehouse/fleet state is touched. A nonexistent worktree path makes both
 # `if [ -d "$WT" ]` guards skip, so teardown runs straight to the cleanup + state rm.
+# make_fake_root <id> [<tasktmp>]: with one argument the meta carries no
+# tasktmp= line at all (a pre-fix task); with two it records the given path.
 make_fake_root() {
-  local id=$1 tasktmp=$2
+  local id=$1 tasktmp_line=
+  [ $# -lt 2 ] || tasktmp_line="tasktmp=$2"
   local fake="$TMP_ROOT/$id"
   mkdir -p "$fake/bin/backends" "$fake/state" "$fake/data"
   # Symlink the REAL teardown so the test exercises actual code, not a copy.
@@ -104,6 +107,14 @@ SH
 exit 0
 SH
   chmod +x "$fake/bin/fm-fleet-sync.sh"
+  # fm-remote-job-reap-orphans.sh: stub (teardown calls it with `|| true`). The
+  # real sweep signals orphaned remote job workers on this machine, so it must
+  # never be symlinked into a fixture.
+  cat > "$fake/bin/fm-remote-job-reap-orphans.sh" <<'SH'
+#!/usr/bin/env bash
+exit 0
+SH
+  chmod +x "$fake/bin/fm-remote-job-reap-orphans.sh"
   # fm-tasks-axi-lib.sh: stub (teardown sources it). Report no backend so the
   # fused backlog close is skipped and the follow-up echo takes the plain-message
   # path; there is no tasks-axi and no backlog in this fixture.
@@ -124,8 +135,8 @@ harness=claude
 kind=ship
 mode=no-mistakes
 yolo=off
-tasktmp=$tasktmp
 META
+  [ -z "$tasktmp_line" ] || printf '%s\n' "$tasktmp_line" >> "$fake/state/$id.meta"
   printf '%s' "$fake"
 }
 
@@ -148,75 +159,50 @@ test_teardown_removes_tasktmp_dir() {
   pass "fm-teardown removes the dir pointed to by tasktmp= in meta"
 }
 
+test_teardown_preserves_replacement_record() {
+  local id=td-replacement-z8 fake task_tmp rc=0
+  task_tmp="$TMP_ROOT/fm-$id"
+  mkdir -p "$task_tmp/gotmp"
+  fake=$(make_fake_root "$id" "$task_tmp")
+  cp "$fake/state/$id.meta" "$fake/replacement.meta"
+  printf 'spawn_gen=replacement\n' >> "$fake/replacement.meta"
+  cat > "$fake/bin/fm-fleet-sync.sh" <<'SH'
+#!/usr/bin/env bash
+set -eu
+. "$FM_HOME/bin/fm-wake-lib.sh"
+meta="$FM_HOME/state/$TEST_REPLACEMENT_ID.meta"
+lock=$(fm_meta_lock_path "$meta")
+fm_lock_try_acquire "$lock"
+trap 'fm_lock_release "$lock"' EXIT
+[ ! -e "$meta" ] && [ ! -L "$meta" ]
+[ ! -e "$TEST_ORIGINAL_TASKTMP" ]
+cp "$FM_HOME/replacement.meta" "$meta"
+SH
+  FM_HOME="$fake" TEST_REPLACEMENT_ID="$id" TEST_ORIGINAL_TASKTMP="$task_tmp" \
+    bash "$fake/bin/fm-teardown.sh" "$id" >"$fake/teardown.stdout" 2>"$fake/teardown.stderr" || rc=$?
+  cmp -s "$fake/replacement.meta" "$fake/state/$id.meta" \
+    || fail "post-cleanup replacement metadata was not published or preserved"
+  [ ! -e "$task_tmp" ] || fail "original task scratch survived cleanup"
+  [ "$rc" -eq 0 ] || {
+    cat "$fake/teardown.stderr" >&2
+    fail "teardown rejected replacement metadata after successful cleanup"
+  }
+  grep -q "teardown $id complete" "$fake/teardown.stdout" \
+    || fail "original teardown did not report completion"
+  if grep -q 'aborted before its task record was removed' "$fake/teardown.stderr"; then
+    fail "completed teardown reported a false abort"
+  fi
+  pass "fm-teardown succeeds and preserves replacement metadata published after cleanup"
+}
+
 test_teardown_skips_gracefully_without_tasktmp() {
   # Backward compat: a meta from a pre-fix task has no tasktmp= line. Teardown must
   # not error and must not remove anything.
   local id=td-absent-z3
-  local fake="$TMP_ROOT/$id-root"
-  mkdir -p "$fake/bin/backends" "$fake/state" "$fake/data"
-  ln -s "$TEARDOWN" "$fake/bin/fm-teardown.sh"
-  ln -s "$ROOT/bin/fm-backend.sh" "$fake/bin/fm-backend.sh"
-  cat > "$fake/bin/backends/tmux.sh" <<'SH'
-fm_backend_tmux_kill() { return 0; }
-SH
-  ln -s "$ROOT/bin/fm-tmux-lib.sh" "$fake/bin/fm-tmux-lib.sh"
-  ln -s "$ROOT/bin/fm-cursor-lib.sh" "$fake/bin/fm-cursor-lib.sh"
-  ln -s "$ROOT/bin/fm-composer-lib.sh" "$fake/bin/fm-composer-lib.sh"
-  ln -s "$ROOT/bin/fm-nm-run-lib.sh" "$fake/bin/fm-nm-run-lib.sh"
-  ln -s "$ROOT/bin/fm-lock-lib.sh" "$fake/bin/fm-lock-lib.sh"
-  # fm-lease-lib.sh: teardown sources it for the supervision lease guard.
-  ln -s "$ROOT/bin/fm-lease-lib.sh" "$fake/bin/fm-lease-lib.sh"
-  ln -s "$ROOT/bin/fm-control-lib.sh" "$fake/bin/fm-control-lib.sh"
-  ln -s "$ROOT/bin/fm-classify-lib.sh" "$fake/bin/fm-classify-lib.sh"
-  # fm-timeout-lib.sh: the shared hard bound fm-classify-lib.sh sources for the
-  # wedge detector's bounded worktree write probe.
-  ln -s "$ROOT/bin/fm-timeout-lib.sh" "$fake/bin/fm-timeout-lib.sh"
-  ln -s "$ROOT/bin/fm-wake-lib.sh" "$fake/bin/fm-wake-lib.sh"
-  # fm-gate-refuse-lib.sh: teardown sources it before any fleet mutation.
-  ln -s "$ROOT/bin/fm-gate-refuse-lib.sh" "$fake/bin/fm-gate-refuse-lib.sh"
-  # fm-pr-lib.sh: teardown uses its canonical task-ID validator for poll cleanup.
-  ln -s "$ROOT/bin/fm-pr-lib.sh" "$fake/bin/fm-pr-lib.sh"
-  # fm-public-followup-lib.sh (and the fm-x-lib.sh it sources): teardown sources
-  # it for the relay-activation gate on the promised-public-reply check. Neither
-  # does anything in this fixture, which has no .env, but both are real siblings
-  # teardown now requires.
-  ln -s "$ROOT/bin/fm-public-followup-lib.sh" "$fake/bin/fm-public-followup-lib.sh"
-  ln -s "$ROOT/bin/fm-x-lib.sh" "$fake/bin/fm-x-lib.sh"
-  ln -s "$ROOT/bin/fm-secondmate-registry-lib.sh" "$fake/bin/fm-secondmate-registry-lib.sh"
-  ln -s "$ROOT/bin/fm-secondmate-parent-lib.sh" "$fake/bin/fm-secondmate-parent-lib.sh"
-  ln -s "$ROOT/bin/fm-pending-reply-lib.sh" "$fake/bin/fm-pending-reply-lib.sh"
-  ln -s "$ROOT/bin/fm-marker-lib.sh" "$fake/bin/fm-marker-lib.sh"
-  ln -s "$ROOT/bin/fm-operational-input.sh" "$fake/bin/fm-operational-input.sh"
-  ln -s "$ROOT/bin/fm-inactive-reconcile.sh" "$fake/bin/fm-inactive-reconcile.sh"
-  ln -s "$ROOT/bin/fm-parent-channel-lib.sh" "$fake/bin/fm-parent-channel-lib.sh"
-  cat > "$fake/bin/fm-guard.sh" <<'SH'
-#!/usr/bin/env bash
-exit 0
-SH
-  chmod +x "$fake/bin/fm-guard.sh"
-  cat > "$fake/bin/fm-fleet-sync.sh" <<'SH'
-#!/usr/bin/env bash
-exit 0
-SH
-  chmod +x "$fake/bin/fm-fleet-sync.sh"
-  cat > "$fake/bin/fm-tasks-axi-lib.sh" <<'SH'
-FM_TASKS_AXI_MIN=0.2.4
-fm_tasks_axi_backend() { printf 'markdown\n'; }
-fm_tasks_axi_backend_available() { return 1; }
-fm_tasks_axi_compatible() { return 1; }
-fm_backlog_backend_manual() { return 1; }
-SH
-  ln -s "$ROOT/bin/fm-backlog-transition-lib.sh" "$fake/bin/fm-backlog-transition-lib.sh"
-  # No tasktmp= line at all.
-  cat > "$fake/state/$id.meta" <<META
-window=fakeses:fm-$id
-worktree=$TMP_ROOT/nonexistent-wt-$id
-project=$TMP_ROOT/nonexistent-proj-$id
-harness=claude
-kind=ship
-mode=no-mistakes
-yolo=off
-META
+  local fake
+  fake=$(make_fake_root "$id")
+  ! grep -q '^tasktmp=' "$fake/state/$id.meta" \
+    || fail "precondition: meta must carry no tasktmp= line"
   FM_HOME="$fake" bash "$fake/bin/fm-teardown.sh" "$id" >/dev/null 2>&1 \
     || fail "teardown exited non-zero when tasktmp= was absent"
   pass "fm-teardown skips gracefully when tasktmp= is absent (backward compat)"
@@ -236,6 +222,169 @@ test_teardown_skips_gracefully_when_dir_missing() {
   pass "fm-teardown skips gracefully when tasktmp= points to a nonexistent dir"
 }
 
+test_teardown_fails_loudly_when_a_sourced_sibling_is_missing() {
+  # POSIX mode makes a missing sourced file fatal on modern Bash too. Default
+  # modern Bash can continue after that error inside a best-effort function;
+  # assuming it always aborts was the old Linux CI failure. The adapter stays
+  # stubbed so this regression never contacts a host tmux server.
+  local id=td-nosib-z5
+  local task_tmp="$TMP_ROOT/fm-$id"
+  mkdir -p "$task_tmp/gotmp"
+  local fake err
+  fake=$(make_fake_root "$id" "$task_tmp")
+  cat > "$fake/bin/backends/tmux.sh" <<'SH'
+: > "$FM_HOME/sibling-source-reached"
+set -o posix
+# shellcheck source=/dev/null
+. "$FM_BACKEND_LIB_DIR/missing-sibling.sh"
+fm_backend_tmux_kill() { return 0; }
+SH
+  err="$TMP_ROOT/$id.stderr"
+  if FM_HOME="$fake" bash "$fake/bin/fm-teardown.sh" "$id" >/dev/null 2>"$err"; then
+    fail "teardown exited 0 with a sourced sibling missing"
+  fi
+  [ -e "$fake/state/$id.meta" ] \
+    || fail "teardown removed the task record after a fatal source failure"
+  [ -e "$task_tmp" ] \
+    || fail "teardown removed the tasktmp dir after a fatal source failure"
+  [ -e "$fake/sibling-source-reached" ] || fail "teardown did not reach the missing sibling"
+  pass "fm-teardown exits non-zero and retains every record when a sourced sibling is missing"
+}
+
+test_teardown_rejects_zero_status_abort() {
+  # Pin the EXIT contract independently of the shell version's source-error
+  # status: an adapter that exits 0 before cleanup is still an aborted teardown.
+  local id=td-zero-z6 fake err task_tmp
+  task_tmp="$TMP_ROOT/fm-$id"
+  mkdir -p "$task_tmp/gotmp"
+  fake=$(make_fake_root "$id" "$task_tmp")
+  printf 'exit 0\n' > "$fake/bin/backends/tmux.sh"
+  err="$TMP_ROOT/$id.stderr"
+  if FM_HOME="$fake" bash "$fake/bin/fm-teardown.sh" "$id" >/dev/null 2>"$err"; then
+    fail "teardown accepted an exit 0 before cleanup"
+  fi
+  [ -e "$fake/state/$id.meta" ] || fail "zero-status abort removed the task record"
+  [ -d "$task_tmp/gotmp" ] || fail "zero-status abort removed task scratch"
+  grep -q "aborted before its task record was removed" "$err" \
+    || fail "zero-status abort did not reach the original stderr"
+  pass "fm-teardown rejects a zero-status abort and reports it on original stderr"
+}
+
+test_missing_adapter_returns_to_caller() {
+  local id=td-noadapter-z7 fake out
+  fake=$(make_fake_root "$id")
+  rm "$fake/bin/backends/tmux.sh"
+  out=$(FM_HOME="$fake" bash --posix -c '
+    . "$1/bin/fm-backend.sh"
+    if fm_backend_source tmux; then exit 1; fi
+    printf "adapter refused\n"
+  ' _ "$fake" 2>&1) || fail "missing adapter aborted instead of returning failure"
+  [ "$out" = 'adapter refused' ] || fail "missing adapter did not reach caller refusal"
+  [ -e "$fake/state/$id.meta" ] || fail "adapter probe removed task metadata"
+  pass "a missing adapter returns failure so the caller can refuse safely"
+}
+
+test_forced_parent_preflights_child_adapters() {
+  local mode id fake home task_tmp child_wt child_tmp err log path
+  for mode in missing-sibling missing-adapter zero-exit kill-failure success; do
+    id="td-child-$mode"
+    task_tmp="$TMP_ROOT/fm-$id"
+    home="$TMP_ROOT/home-$id"
+    child_wt="$TMP_ROOT/work-$id"
+    child_tmp="$home/tasktmp"
+    mkdir -p "$task_tmp/gotmp" "$home/state" "$child_tmp/gotmp" "$child_wt"
+    fake=$(make_fake_root "$id" "$task_tmp")
+    printf '%s\n' "$id" > "$home/.fm-secondmate-home"
+    printf 'parent work\n' > "$home/work-note"
+    printf 'parent scratch\n' > "$task_tmp/gotmp/artifact"
+    printf 'child scratch\n' > "$child_tmp/gotmp/artifact"
+    git -C "$child_wt" init -q || fail "child fixture git init failed"
+    git -C "$child_wt" -c user.name=Test -c user.email=test@example.invalid \
+      -c commit.gpgsign=false commit -q --allow-empty -m fixture \
+      || fail "child fixture commit failed"
+    printf 'child work\n' > "$child_wt/work-note"
+    cat > "$fake/state/$id.meta" <<META
+window=fakeses:fm-$id
+worktree=$home
+home=$home
+project=$TMP_ROOT/nonexistent-project-$id
+kind=secondmate
+tasktmp=$task_tmp
+META
+    cat > "$home/state/child-z.meta" <<META
+backend=zellij
+window=fakeses:1
+zellij_session=fakeses
+zellij_tab_id=1
+zellij_pane_id=1
+endpoint_task_id=child-z
+worktree=$child_wt
+project=$child_wt
+kind=ship
+mode=local-only
+tasktmp=$child_tmp
+META
+    cp "$fake/state/$id.meta" "$fake/parent.meta.before"
+    cp "$home/state/child-z.meta" "$fake/child.meta.before"
+    : > "$fake/bin/backends/zellij.sh"
+    if [ "$mode" = missing-sibling ]; then
+      printf 'set -o posix\n' >> "$fake/bin/backends/zellij.sh"
+    fi
+    cat >> "$fake/bin/backends/zellij.sh" <<'SH'
+. "$FM_BACKEND_LIB_DIR/fm-backend-hometag-lib.sh"
+fm_backend_zellij_kill() {
+  printf '%s\n' "$FM_HOME" "$FM_ROOT" "$@" >> "$TEST_CHILD_KILL_LOG"
+  return "$TEST_CHILD_KILL_RC"
+}
+SH
+    case "$mode" in
+      missing-sibling) ;;
+      missing-adapter) rm "$fake/bin/backends/zellij.sh" ;;
+      zero-exit) printf 'exit 0\n' > "$fake/bin/fm-backend-hometag-lib.sh" ;;
+      *) : > "$fake/bin/fm-backend-hometag-lib.sh" ;;
+    esac
+    printf '#!/usr/bin/env bash\nexit 1\n' > "$fake/bin/treehouse"
+    chmod +x "$fake/bin/treehouse"
+    err="$fake/teardown.stderr"
+    log="$fake/child-kill.log"
+    local kill_rc=0 rc=0
+    [ "$mode" != kill-failure ] || kill_rc=1
+    FM_HOME="$fake" PATH="$fake/bin:$PATH" TEST_CHILD_KILL_LOG="$log" TEST_CHILD_KILL_RC="$kill_rc" \
+      bash "$fake/bin/fm-teardown.sh" "$id" --force > "$fake/teardown.stdout" 2>"$err" || rc=$?
+    case "$mode" in
+      missing-sibling|missing-adapter|zero-exit)
+        [ "$rc" -ne 0 ] || fail "$mode: forced parent teardown accepted child adapter failure"
+        cmp -s "$fake/state/$id.meta" "$fake/parent.meta.before" || fail "$mode: parent record changed"
+        cmp -s "$home/state/child-z.meta" "$fake/child.meta.before" || fail "$mode: child record changed"
+        [ "$(cat "$home/work-note")" = 'parent work' ] || fail "$mode: parent work changed"
+        [ "$(cat "$child_wt/work-note")" = 'child work' ] || fail "$mode: child work changed"
+        [ "$(cat "$task_tmp/gotmp/artifact")" = 'parent scratch' ] || fail "$mode: parent scratch changed"
+        [ "$(cat "$child_tmp/gotmp/artifact")" = 'child scratch' ] || fail "$mode: child scratch changed"
+        [ ! -e "$log" ] || fail "$mode: child kill ran before preflight completed"
+        case "$mode" in
+          missing-sibling) grep -q 'fm-backend-hometag-lib.sh' "$err" || fail "missing sibling diagnostic absent: $(cat "$err")" ;;
+          missing-adapter) grep -q 'REFUSED: zellij adapter is unavailable for child child-z' "$err" || fail "missing adapter refusal absent: $(cat "$err")" ;;
+          zero-exit) grep -q 'aborted before its task record was removed' "$err" || fail "zero-status abort diagnostic absent: $(cat "$err")" ;;
+        esac
+        ;;
+      *)
+        [ "$rc" -eq 0 ] || { cat "$err" >&2; fail "$mode: forced parent teardown failed"; }
+        for path in "$fake/state/$id.meta" "$home" "$child_wt" "$task_tmp"; do
+          [ ! -e "$path" ] || fail "$mode: cleanup retained $path"
+        done
+        printf '%s\n' "$home" "$home" fakeses:1 1 fm-child-z > "$fake/expected-kill.log"
+        cmp -s "$log" "$fake/expected-kill.log" || fail "$mode: child kill lost its owning home or endpoint"
+        ;;
+    esac
+    pass "forced parent child-adapter preflight: $mode"
+  done
+}
+
 test_teardown_removes_tasktmp_dir
+test_teardown_preserves_replacement_record
 test_teardown_skips_gracefully_without_tasktmp
 test_teardown_skips_gracefully_when_dir_missing
+test_teardown_fails_loudly_when_a_sourced_sibling_is_missing
+test_teardown_rejects_zero_status_abort
+test_missing_adapter_returns_to_caller
+test_forced_parent_preflights_child_adapters