fleetd #593 (pid-count half): running_pid() no longer matches the caller

running_pid() was a bare `pgrep -f "$PATTERN"`, which matches ANY process whose
full command line contains the pattern text -- including a shell that merely
embeds it as literal text (a hand-typed investigation, an ssh-shaped
`sh -c '...; ...'`, or a pipeline) rather than being the daemon. That self-match
turns a working redeploy into a reported "racing supervisor" failure via
assert_single_daemon.

pgrep -c does not exist on BSD/macOS, so this can't be fixed by switching flags.
running_pid() now keeps pgrep to find candidates (portable), then drops any
candidate whose process name (comm) names a shell -- the daemon is always
`java`, so a self-matching wrapper of this shape is always excluded while a
genuine second daemon-shaped process still counts.

assert_single_daemon's die message no longer hands the operator a bare
`pgrep -f "$PATTERN"` as remediation -- that was exactly the self-matching
invocation -- and now says in words that a pattern can match the caller.

Adds three tests: a self-matching wrapper shell must be excluded, a real
second daemon-shaped process must still be found, and the die message must
not recommend the self-matching command. Verified the first test fails
against the pre-fix implementation (confirmed the regression is caught).

Leaves instance 1 (the fleetd.out log source, systemd-only) for a Linux host,
per the ticket's scope split.

scripts/test-redeploy-fleetd.sh

@@ -433,6 +433,67 @@ test_assert_single_daemon_rejects_two_pids() {
   printf '%s' "$output" | grep -qF '4343' || fail "refusal message does not list the pids it found"
 }
 
+# fleetd #593 instance 2 — `running_pid()` used to be a bare `pgrep -f "$PATTERN"`, which matches
+# ANY process whose full command line contains the pattern TEXT, including a shell that merely
+# embeds it as literal text rather than being the daemon. Measured live on this Mac: `pgrep -c`
+# (a one-call count) does not exist on BSD at all, and `bash -c "<single command>"` execs in place
+# so no parent shell survives to hold the pattern — which is exactly why the defect did not
+# reproduce from a plain script and needs a wrapper shaped like this instead. A `sh -c '...; ...'`
+# with MORE THAN ONE statement does not get that exec-in-place treatment: the shell forks a child
+# for the second statement and stays alive itself, holding the whole `-c` string — pattern text
+# included — in its own `ps -o args`, for as long as it runs. That is the same shape an
+# `ssh host "…; …"` wrapper or a hand-typed pipeline leaves behind. Before the fix this test would
+# have found the wrapper's pid in running_pid()'s output; it must not.
+test_running_pid_excludes_self_matching_wrapper_shell() {
+  local before after wrapper_pid
+  before="$(running_pid)"
+  sh -c 'echo "target/fleetd.jar" >/dev/null; sleep 20' &
+  wrapper_pid=$!
+  sleep 0.3
+  after="$(running_pid)"
+  kill "$wrapper_pid" 2>/dev/null || true
+  wait "$wrapper_pid" 2>/dev/null || true
+  [ "$after" = "$before" ] \
+    || fail "running_pid() counted a self-matching wrapper shell (pid $wrapper_pid, holding the pattern as literal text in its own argv, not the daemon): before=[$before] after=[$after]"
+}
+
+# fleetd #593 instance 2, the other half — the fix above must not exclude too much. A genuine
+# daemon-shaped process (comm is not a shell) whose own argv holds the pattern must still be
+# found. `exec -a` gives a harmless `sleep` an argv[0] containing the pattern without starting a
+# real JVM: copying a system binary into a scratch path and executing it from there was tried
+# first and the OS killed it outright (SIGKILL, exit 137 — almost certainly a code-signing check),
+# so this uses `exec -a` instead, which needs no binary of its own and nothing under a scratch
+# directory.
+test_running_pid_still_finds_a_real_second_process() {
+  local before after standin_pid
+  before="$(running_pid)"
+  ( exec -a "fleetd-593-test-standin-target/fleetd.jar" sleep 20 ) &
+  standin_pid=$!
+  sleep 0.3
+  after="$(running_pid)"
+  kill "$standin_pid" 2>/dev/null || true
+  wait "$standin_pid" 2>/dev/null || true
+  printf '%s\n' "$after" | grep -qxF "$standin_pid" \
+    || fail "running_pid() did not find a real second daemon-shaped process (pid $standin_pid) whose own argv holds the pattern: before=[$before] after=[$after]"
+}
+
+# fleetd #593 instance 3 — assert_single_daemon's refusal message used to tell the operator to
+# "Investigate with 'pgrep -f \"\$PATTERN\"'", which — typed by hand or over ssh — is precisely the
+# self-matching invocation instance 2 above fixes. A source-text check, the same technique
+# test_no_error_lines_message_gated_by_drain_state uses: this is prose inside a die() call, never
+# reached by sourcing (the SOURCED guard stops before the main flow, and this text only prints
+# from inside a call assert_single_daemon makes when it is already refusing).
+test_die_message_does_not_recommend_bare_pgrep_as_remediation() {
+  local src="$ROOT/scripts/redeploy-fleetd.sh" block bad
+  block="$(grep -A6 -F 'racing supervisor produces' "$src" || true)"
+  [ -n "$block" ] || fail "could not find the assert_single_daemon refusal message in redeploy-fleetd.sh"
+  bad="$(printf '%s' "$block" | grep -F "Investigate with 'pgrep -f" || true)"
+  [ -z "$bad" ] \
+    || fail "assert_single_daemon's die message still hands the operator a bare 'pgrep -f \"\$PATTERN\"' as remediation (fleetd #593) — that is exactly the self-matching invocation"
+  printf '%s' "$block" | grep -qF 'fleetd #593' \
+    || fail "assert_single_daemon's die message does not say in words that a pattern can match the caller (fleetd #593)"
+}
+
 # fleetd #511 — jar_id()'s no-argument default was unpinned by any test: nothing proved it reports
 # $JAR (the live path) rather than $JAR_STAGED. Both halves matter, so this pins both: the bare call
 # must hash the live jar, and an explicit path argument must hash THAT file, not fall back to $JAR.
@@ -1894,6 +1955,9 @@ test_require_drivable_supervisor_accepts_known_kinds
 test_count_daemon_pids
 test_assert_single_daemon_accepts_one_pid
 test_assert_single_daemon_rejects_two_pids
+test_running_pid_excludes_self_matching_wrapper_shell
+test_running_pid_still_finds_a_real_second_process
+test_die_message_does_not_recommend_bare_pgrep_as_remediation
 test_jar_id_defaults_to_live_and_reports_explicit_path
 test_hash256_computes_a_real_sha256
 test_jar_id_reports_absent_for_missing_file