Close the squad P1 gaps the audit listed for this batch

Why: parallel groups dropped a hold, HITL timeouts were unused, the planner failed closed on any model error, and event sequence numbers restarted at 1.
Evidence: GOWORK=off go test -count=1 -race ./squad/ ./squadintent/ ./store/ ./platform/ passed, including TestR2ExpiredDecisionUsesCancel, TestR2IntentStepSkipsRoleRegistry, TestR2PlannerFallsBackAndCapsSteps, TestR2TaskFileUsesLatestBlackboard, TestR2FanoutCancelDoesNotPanic, TestR2EventSeqContinuesAfterRestart, TestR2JournalModeWAL, and TestR2GateReloadSeesNewIntent.
Impact: a failed or held parallel sibling cancels the rest; expired requests synthesize cancel or fail; the intent gate follows Registry.Reload.
Refs: Q6, Q10, Q11, Q12, Q13, Q17, Q18, Q19, I9
Co-authored-by: Cursor <cursoragent@cursor.com>

store/eventsink.go

@@ -1,6 +1,7 @@
 package store
 
 import (
+	"bufio"
 	"encoding/json"
 	"os"
 	"path/filepath"
@@ -58,6 +59,7 @@ func (s *FileEventSink) Emit(ev squad.Event) {
 		}
 		f = fp
 		s.files[ev.RunID] = f
+		s.seqs[ev.RunID] = lastEventSeq(filepath.Join(dir, "events.jsonl"))
 	}
 	s.seqs[ev.RunID]++
 	line := persistedEvent{Seq: s.seqs[ev.RunID], Type: ev.Type, StepID: ev.StepID,
@@ -72,6 +74,23 @@ func (s *FileEventSink) Emit(ev squad.Event) {
 	_, _ = f.Write(append(data, '\n'))
 }
 
+func lastEventSeq(path string) int64 {
+	f, err := os.Open(path)
+	if err != nil {
+		return 0
+	}
+	defer f.Close()
+	var last int64
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		var line persistedEvent
+		if err := json.Unmarshal(sc.Bytes(), &line); err == nil && line.Seq > last {
+			last = line.Seq
+		}
+	}
+	return last
+}
+
 // Close 关闭全部文件句柄。
 func (s *FileEventSink) Close() {
 	s.mu.Lock()

store/r2_regression_test.go

@@ -0,0 +1,27 @@
+package store
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"agent-squad/squad"
+)
+
+func TestR2EventSeqContinuesAfterRestart(t *testing.T) {
+	dir := t.TempDir()
+	run := "run_1"
+	path := filepath.Join(dir, "runs", run)
+	if err := os.MkdirAll(path, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(path, "events.jsonl"), []byte("{\"seq\":7,\"type\":\"phase\"}\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	sink := NewFileEventSink(dir, nil)
+	sink.Emit(squad.Event{Type: "phase", RunID: run, Text: "next"})
+	sink.Close()
+	if got := lastEventSeq(filepath.Join(path, "events.jsonl")); got != 8 {
+		t.Fatalf("seq %d", got)
+	}
+}