1 files changed, 28 insertions, 7 deletions

diff --git a/internal/storage/events.go b/internal/storage/events.go
index 82016ab..2051127 100644
--- a/internal/storage/events.go
+++ b/internal/storage/events.go
@@ -1,6 +1,7 @@
 package storage
 
 import (
+	"database/sql"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -8,12 +9,29 @@ import (
 
 	"github.com/google/uuid"
 	"github.com/thepeterstone/claudomator/internal/event"
+	"github.com/thepeterstone/claudomator/internal/task"
 )
 
 // CreateEvent appends an event to a task's stream. Seq is assigned by the
 // database as MAX(seq)+1 within a transaction. On return, e.ID, e.Seq, and
 // e.Timestamp are populated (timestamps default to time.Now().UTC()).
 func (s *DB) CreateEvent(e *event.Event) error {
+	tx, err := s.db.Begin()
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback()
+	if err := createEventTx(tx, e); err != nil {
+		return err
+	}
+	return tx.Commit()
+}
+
+// createEventTx validates, defaults, assigns a per-task monotonic seq, and
+// inserts an event using the supplied transaction. The caller commits. This
+// lets state-changing methods write their state_change event atomically with
+// the row update.
+func createEventTx(tx *sql.Tx, e *event.Event) error {
 	if e == nil {
 		return errors.New("event is nil")
 	}
@@ -38,12 +56,6 @@ func (s *DB) CreateEvent(e *event.Event) error {
 		e.Timestamp = e.Timestamp.UTC()
 	}
 
-	tx, err := s.db.Begin()
-	if err != nil {
-		return err
-	}
-	defer tx.Rollback()
-
 	var nextSeq int64
 	if err := tx.QueryRow(`SELECT COALESCE(MAX(seq), 0) + 1 FROM events WHERE task_id = ?`, e.TaskID).Scan(&nextSeq); err != nil {
 		return fmt.Errorf("computing next seq: %w", err)
@@ -56,7 +68,16 @@ func (s *DB) CreateEvent(e *event.Event) error {
 	); err != nil {
 		return fmt.Errorf("inserting event: %w", err)
 	}
-	return tx.Commit()
+	return nil
+}
+
+// stateChangePayload builds the JSON payload for a state_change event.
+func stateChangePayload(from, to task.State) json.RawMessage {
+	b, _ := json.Marshal(struct {
+		From task.State `json:"from"`
+		To   task.State `json:"to"`
+	}{From: from, To: to})
+	return b
 }
 
 // ListEvents returns events for a task in seq order. Pass sinceSeq=0 for the