test: back Herdr live-duplicate agent registrations with a running process

docs/verification/runtime-backends.md

@@ -1707,6 +1707,22 @@ herdr pane process-info --pane w1:p1 --session "$LAB" | jq -c '.result.process_i
 Before the fix `fm_backend_agent_state herdr` read that second state as `alive`, so `bin/fm-control.sh <id> relaunch` and `bin/fm-spawn.sh --relaunch` were refused for as long as the registration lived, which is hours.
 The registration is still present after the wait, and a `pane report-agent` registration whose agent process exits under a nested shell leaves the same shape behind on any pane, which is what the lifecycle-control guard uses; with no nested shell, Herdr releases that registration within about a second.
 
+Measured 2026-10-01 on Linux x86_64 against Herdr 0.9.3 in an isolated `fm-lab-` session: a registration on a pane idling at its own top shell is released within about a second, while a nested shell in the foreground keeps it.
+A fixture that needs a lasting registration therefore backs it with a running foreground process, as the live-duplicate case in `tests/fm-backend-herdr-smoke.test.sh` does.
+
+```sh
+herdr pane report-agent w1:p1 --source fm-probe --agent probe-agent --state idle --session "$LAB"; sleep 2
+herdr agent get w1:p1 --session "$LAB" 2>&1
+herdr pane run w1:p1 bash --session "$LAB"; sleep 1
+herdr pane report-agent w1:p1 --source fm-probe --agent probe-agent --state idle --session "$LAB"; sleep 2
+herdr agent get w1:p1 --session "$LAB" | jq -c '.result.agent | {agent, agent_status}'
+```
+
+```text
+{"error":{"code":"agent_not_found","message":"agent target w1:p1 not found"},"id":"cli:agent:get"}
+{"agent":"probe-agent","agent_status":"idle"}
+```
+
 Two vendor facts the fix rests on, both read from the outputs above and from `fm_backend_herdr_pane_process_state`'s `pane process-info` parse:
 
 - Pi's process presents with kernel name `node` and argv0 `pi` (its foreground group also carries Pi's child `node` helpers with argv0 such as `npm view ... version`), so a running Pi is attributed by argv[0] exactly as the tmux probe attributes it; a symlink named `claude` to `sleep` presents as name `sleep`, argv0 `claude`.

tests/fm-backend-herdr-respawn-idem-e2e.test.sh

@@ -163,9 +163,32 @@ pass "fixed: the workspace holds exactly the 2 replacement tabs after both respa
 # the freshly-respawned panes, then confirm a further same-labeled spawn
 # attempt refuses exactly as before - the husk fix must never touch a pane
 # that actually has something registered in it.
-
+# The registration is backed by a running agent-named foreground process
+# (a `claude` symlink to `sleep`, as tests/fm-backend-herdr-smoke.test.sh
+# does): Herdr 0.9.3 releases a report-agent registration within about a
+# second once the pane's foreground is its own top shell, so a report on an
+# idle shell pane is not a live agent and would race that release
+# (docs/verification/runtime-backends.md "Stale agent registration").
+
+LIVE_SLEEP=$(command -v sleep) || fail "sleep not found"
+ln -s "$LIVE_SLEEP" "$SCRATCH/claude"
+printf -v LIVE_AGENT_Q '%q' "$SCRATCH/claude"
+fm_backend_herdr_send_text_line "$SESSION:$NEW_CREW_PANE_ID" "$LIVE_AGENT_Q 900" \
+  || fail "could not start the agent-named foreground process on the respawned crewmate-shaped pane"
+LIVE_TRIES=0
+until [ "$(fm_backend_herdr_pane_process_state "$SESSION" "$NEW_CREW_PANE_ID")" = agent ]; do
+  LIVE_TRIES=$((LIVE_TRIES + 1))
+  [ "$LIVE_TRIES" -lt 50 ] \
+    || fail "the respawned crewmate-shaped pane's agent-named foreground process reads '$(fm_backend_herdr_pane_process_state "$SESSION" "$NEW_CREW_PANE_ID")' rather than 'agent' through pane process-info"
+  sleep 0.1
+done
 herdr pane report-agent "$NEW_CREW_PANE_ID" --source fm-respawn-e2e --agent fm-respawn-live-agent --state idle --session "$SESSION" >/dev/null 2>&1 \
   || fail "could not register a live agent on the respawned crewmate-shaped pane"
+# Prove the scenario is the live case rather than passing on a stale or
+# unreadable registration, which the husk check also refuses.
+LIVE_STATE=$(fm_backend_herdr_pane_agent_state "$SESSION" "$NEW_CREW_PANE_ID")
+[ "$LIVE_STATE" = live ] \
+  || fail "live-duplicate setup is wrong: the respawned crewmate-shaped pane should classify live, got '$LIVE_STATE'"
 
 if fm_backend_herdr_create_task "$CONTAINER" "$CREW_LABEL" "$PROJ_CWD" >/dev/null 2>&1; then
   fail "REGRESSION: create_task should refuse a same-labeled tab whose pane hosts a genuinely live registered agent"

tests/fm-backend-herdr-smoke.test.sh

@@ -35,8 +35,10 @@ herdr_forget_inherited_pane
 SESSION="fm-lab-backend-smoke-$$"
 export HERDR_SESSION="$SESSION"
 SM_SCRATCH=
+LIVE_DUP_SCRATCH=
 cleanup_all() {
   [ -n "$SM_SCRATCH" ] && rm -rf "$SM_SCRATCH"
+  [ -n "$LIVE_DUP_SCRATCH" ] && rm -rf "$LIVE_DUP_SCRATCH"
   herdr_safe_stop_and_delete "$SESSION"
 }
 trap cleanup_all EXIT
@@ -133,6 +135,12 @@ pass "real herdr: create_task prunes the freshly-created workspace's seeded defa
 
 # 1. A genuinely LIVE duplicate (a real registered agent, via herdr's own
 #    `pane report-agent`) must still refuse exactly as before.
+#    The registration is backed by a running agent-named foreground process
+#    (a `claude` symlink to `sleep`, as tests/fm-control-herdr-smoke.test.sh
+#    does): Herdr 0.9.3 releases a report-agent registration within about a
+#    second once the pane's foreground is its own top shell, so a report on an
+#    idle shell pane is not a live agent and would race that release
+#    (docs/verification/runtime-backends.md "Stale agent registration").
 LIVE_DUP_LABEL="fm-smoke-livedup"
 LIVE_DUP_IDS=$(fm_backend_herdr_create_task "$CONTAINER" "$LIVE_DUP_LABEL" /tmp) || fail "could not create the live-duplicate scenario's tab"
 read -r LIVE_DUP_TAB_ID LIVE_DUP_PANE_ID <<EOF
@@ -141,8 +149,26 @@ EOF
 if [ -z "$LIVE_DUP_TAB_ID" ] || [ -z "$LIVE_DUP_PANE_ID" ]; then
   fail "live-duplicate scenario tab creation did not return ids"
 fi
+LIVE_DUP_SCRATCH=$(mktemp -d "${TMPDIR:-/tmp}/fm-herdr-smoke-livedup.XXXXXX")
+LIVE_DUP_SLEEP=$(command -v sleep) || fail "sleep not found"
+ln -s "$LIVE_DUP_SLEEP" "$LIVE_DUP_SCRATCH/claude"
+printf -v LIVE_DUP_AGENT_Q '%q' "$LIVE_DUP_SCRATCH/claude"
+fm_backend_herdr_send_text_line "$SESSION:$LIVE_DUP_PANE_ID" "$LIVE_DUP_AGENT_Q 900" \
+  || fail "could not start the agent-named foreground process in the live-duplicate scenario's pane"
+LIVE_DUP_TRIES=0
+until [ "$(fm_backend_herdr_pane_process_state "$SESSION" "$LIVE_DUP_PANE_ID")" = agent ]; do
+  LIVE_DUP_TRIES=$((LIVE_DUP_TRIES + 1))
+  [ "$LIVE_DUP_TRIES" -lt 50 ] \
+    || fail "the live-duplicate scenario's agent-named foreground process reads '$(fm_backend_herdr_pane_process_state "$SESSION" "$LIVE_DUP_PANE_ID")' rather than 'agent' through pane process-info"
+  sleep 0.1
+done
 herdr pane report-agent "$LIVE_DUP_PANE_ID" --source fm-smoke-test --agent fm-smoke-live-agent --state idle --session "$SESSION" >/dev/null 2>&1 \
   || fail "could not register a live agent on the live-duplicate scenario's pane"
+# Prove the scenario is the live case rather than passing on a stale or
+# unreadable registration, which the husk check also refuses.
+LIVE_DUP_STATE=$(fm_backend_herdr_pane_agent_state "$SESSION" "$LIVE_DUP_PANE_ID")
+[ "$LIVE_DUP_STATE" = live ] \
+  || fail "live-duplicate scenario setup is wrong: the pane should classify live, got '$LIVE_DUP_STATE'"
 if fm_backend_herdr_create_task "$CONTAINER" "$LIVE_DUP_LABEL" /tmp >/dev/null 2>&1; then
   fail "REGRESSION: create_task should refuse a duplicate label whose pane hosts a genuinely live registered agent (idle counts as live)"
 fi