fix(resume): allow fresh spawn fallback and refresh epoch on 0-turn Class A resume

- Branch on Class A agents (agy, hermes, opencode) in resume_session.sh to fall back to clean spawn (CMD_FULL) when stopped before first turn (empty UUID)
- Update update_yaml_resumed.sh to support empty UUID with --cmd-full and refresh herdr_session_epoch on fresh spawn resume to prevent stale transcript capture
- Strictly preserve Class B (claude, grok) assigned UUID escape hatch and test_t8 contract
- Add regression tests test_t14, test_t15, test_t16 (Closes #3 Item 2)

.agents/skills/multi-agent-mux-resume/scripts/update_yaml_resumed.sh

@@ -11,7 +11,11 @@ source "$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)/lib.sh"
 
 usage() {
   cat <<EOF
-Usage: $0 --session <name> --uuid <id> [--agent claude|agy|hermes|grok|opencode] [--herdr-session <name>]
+Usage: $0 --session <name> --uuid <id> [--agent claude|agy|hermes|grok|opencode] [--herdr-session <name>] [--cmd-full <cmd>]
+
+--uuid may be empty for an Issue-3 Class A fresh-spawn resume (agy/hermes/
+opencode 0-turn stopped session, no conversation id ever assigned) - pass
+--cmd-full so the display command can be recorded without a uuid to embed.
 EOF
 }
 
@@ -22,6 +26,7 @@ WORKSPACE=""
 ROLE=""
 HERDR_SERVER_OPT=""
 HERDR_WORKSPACE_OPT=""
+CMD_FULL_OPT=""
 
 while [ $# -gt 0 ]; do
   case "$1" in
@@ -32,13 +37,13 @@ while [ $# -gt 0 ]; do
     --role)      ROLE="$2";          shift 2 ;;
     --herdr-session|--herdr-server) HERDR_SERVER_OPT="$2"; shift 2 ;;
     --herdr-workspace) HERDR_WORKSPACE_OPT="$2"; shift 2 ;;
+    --cmd-full)  CMD_FULL_OPT="$2";  shift 2 ;;
     -h|--help) usage; exit 0 ;;
     *) echo "ERROR: unknown arg: $1" >&2; exit 2 ;;
   esac
 done
 
 [ -n "$SESSION_NAME" ] || { echo "ERROR: --session required" >&2; exit 2; }
-[ -n "$UUID" ]        || { echo "ERROR: --uuid required" >&2; exit 2; }
 [ -f "$AGENT_SESSIONS_YAML" ] || { echo "ERROR: $AGENT_SESSIONS_YAML not found" >&2; exit 1; }
 
 if [ -n "$HERDR_SERVER_OPT" ]; then
@@ -104,7 +109,8 @@ atomic_dump_yaml "$AGENT_SESSIONS_YAML" \
   SESSION_NAME="$SESSION_NAME" UUID="$UUID" AGENT="$AGENT" NOW_ISO="$NOW_ISO" \
   NOW_EPOCH="$NOW_EPOCH" TARGET_WORKSPACE="${WORKSPACE:-$WORKSPACE_ROOT}" ROLE="$ROLE" \
   PANE_PID="$PANE_PID" CHILD_PID="$CHILD_PID" HERDR_SERVER_OPT_EXPLICIT="${HERDR_SERVER_OPT_EXPLICIT:-0}" \
-  MAM_WS_LABEL="$MAM_WS_LABEL" MAM_WS_LABEL_EXPLICIT="${MAM_WS_LABEL_EXPLICIT:-0}" <<'PYEOF'
+  MAM_WS_LABEL="$MAM_WS_LABEL" MAM_WS_LABEL_EXPLICIT="${MAM_WS_LABEL_EXPLICIT:-0}" \
+  CMD_FULL_OPT="$CMD_FULL_OPT" <<'PYEOF'
 name = os.environ['SESSION_NAME']
 uuid = os.environ['UUID']
 agent = os.environ['AGENT']
@@ -157,6 +163,18 @@ else:
         target['herdr_workspace'] = wsl
 
 target['status'] = 'running'
+if not uuid:
+    # ISSUE-3 (challenge c4b0a075): a Class A fresh-spawn resume re-arms
+    # discovery from scratch - the resumed agent has not spoken yet, so any
+    # on-disk conversation older than THIS resume must not be auto-pinned to
+    # it by reconcile.sh's mode="discover" mtime >= epoch check. Without this,
+    # the row's watermark stays at the original create_session.sh timestamp,
+    # letting reconcile.sh capture a stale/unrelated transcript before the
+    # resumed agent's first real turn.
+    target['herdr_session_epoch'] = epoch
+    target['herdr_session_created_at'] = now
+    target['session_id_source'] = 'pending-discovery'
+    target['session_id_verified'] = False
 target.pop('terminated_at', None)
 target.pop('terminated_at_epoch', None)
 target.pop('termination_mode', None)
@@ -166,7 +184,11 @@ target.pop('stopped_at', None)
 target.pop('stopped_at_epoch', None)
 target.pop('stop_reason', None)
 target.pop('resumable', None)
-target['last_visible_status'] = f'resumed conversation {uuid} at {now}'
+if uuid:
+    target['last_visible_status'] = f'resumed conversation {uuid} at {now}'
+else:
+    # ISSUE-3 Class A fresh-spawn resume: no conversation id existed yet.
+    target['last_visible_status'] = f'resumed (fresh spawn, no prior turn) at {now}'
 
 target.setdefault('pane', {})
 if pane_pid.isdigit():
@@ -178,15 +200,21 @@ if agent == 'claude':
     target['claude_session_id_own'] = uuid
 elif agent == 'agy':
     target['pane']['cmd'] = 'agy'
-    target['pane']['cmd_full'] = f'agy --dangerously-skip-permissions --conversation {uuid}'
-    target['agy_conversation_id_own'] = uuid
+    if uuid:
+        target['pane']['cmd_full'] = f'agy --dangerously-skip-permissions --conversation {uuid}'
+        target['agy_conversation_id_own'] = uuid
+    else:
+        target['pane']['cmd_full'] = os.environ.get('CMD_FULL_OPT', '') or 'agy --dangerously-skip-permissions'
     cp = os.environ.get('CHILD_PID', '0')
     if cp.isdigit() and int(cp) > 0:
         target['child_pid'] = int(cp)
 elif agent == 'hermes':
     target['pane']['cmd'] = 'hermes'
-    target['pane']['cmd_full'] = f'hermes --resume {uuid}'
-    target['hermes_conversation_id_own'] = uuid
+    if uuid:
+        target['pane']['cmd_full'] = f'hermes --resume {uuid}'
+        target['hermes_conversation_id_own'] = uuid
+    else:
+        target['pane']['cmd_full'] = os.environ.get('CMD_FULL_OPT', '') or 'hermes --yolo --accept-hooks'
     cp = os.environ.get('CHILD_PID', '0')
     if cp.isdigit() and int(cp) > 0:
         target['child_pid'] = int(cp)
@@ -199,8 +227,11 @@ elif agent == 'grok':
         target['child_pid'] = int(cp)
 elif agent == 'opencode':
     target['pane']['cmd'] = 'opencode'
-    target['pane']['cmd_full'] = f'opencode --session {uuid} --auto --agent build'
-    target['opencode_session_id_own'] = uuid
+    if uuid:
+        target['pane']['cmd_full'] = f'opencode --session {uuid} --auto --agent build'
+        target['opencode_session_id_own'] = uuid
+    else:
+        target['pane']['cmd_full'] = os.environ.get('CMD_FULL_OPT', '') or 'opencode --auto --agent build'
     cp = os.environ.get('CHILD_PID', '0')
     if cp.isdigit() and int(cp) > 0:
         target['child_pid'] = int(cp)