Guard plan drafts against swaps and keep confirm on single-flight

Return the draft job id as jobId, as the plan API contract specifies.

Add a week_plans revision (migration 0013) that every swap and stored
draft raises. A draft_week job reads the revision before draft_week runs
and stores its week only while the plan still has it; a plan edited
while the AI ran is left as it is and the job fails plan_changed, so a
draft never erases the household's swap.

A confirmed draft now joins only a confirmed queued or running job, so a
job asked for without confirm can no longer fail it with
confirm_required after the plan was synced.

Test simultaneous drafts, a swap during a draft, a confirmed draft while
an unconfirmed one runs, impossible calendar dates and start_by across
the end of daylight saving time.

Maestro task ea48e650-d510-49cc-8485-0f07174ee731.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/db/models.go

@@ -316,4 +316,5 @@ type WeekPlan struct {
 	CalendarSyncedAt sql.NullString
 	CreatedAt        string
 	UpdatedAt        string
+	Revision         int64
 }

internal/db/plans.sql.go

@@ -39,6 +39,7 @@ SELECT id FROM jobs
 WHERE kind = ?1
 	AND status IN ('queued', 'running')
 	AND json_extract(payload, '$.week_start') = ?2
+	AND (CAST(?3 AS INTEGER) = 0 OR json_extract(payload, '$.confirm') = 1)
 ORDER BY id
 LIMIT 1
 `
@@ -46,19 +47,21 @@ LIMIT 1
 type GetActiveDraftJobIDParams struct {
 	Kind      string
 	WeekStart string
+	Confirmed int64
 }
 
 // The id of the job of kind queued or running for the week starting
-// week_start. Returns sql.ErrNoRows when there is none.
+// week_start, one whose payload has confirm when confirmed is 1. Returns
+// sql.ErrNoRows when there is none.
 func (q *Queries) GetActiveDraftJobID(ctx context.Context, arg GetActiveDraftJobIDParams) (string, error) {
-	row := q.db.QueryRowContext(ctx, getActiveDraftJobID, arg.Kind, arg.WeekStart)
+	row := q.db.QueryRowContext(ctx, getActiveDraftJobID, arg.Kind, arg.WeekStart, arg.Confirmed)
 	var id string
 	err := row.Scan(&id)
 	return id, err
 }
 
 const getWeekPlan = `-- name: GetWeekPlan :one
-SELECT id, week_start, status, ai_note, ai_run_id, calendar_synced_at, created_at, updated_at FROM week_plans
+SELECT id, week_start, status, ai_note, ai_run_id, calendar_synced_at, created_at, updated_at, revision FROM week_plans
 WHERE week_start = ?
 `
 
@@ -76,6 +79,7 @@ func (q *Queries) GetWeekPlan(ctx context.Context, weekStart string) (WeekPlan,
 		&i.CalendarSyncedAt,
 		&i.CreatedAt,
 		&i.UpdatedAt,
+		&i.Revision,
 	)
 	return i, err
 }
@@ -241,6 +245,7 @@ func (q *Queries) ListWeekPlanDinnerIDs(ctx context.Context, weekStart string) (
 const markWeekPlanEdited = `-- name: MarkWeekPlanEdited :exec
 UPDATE week_plans
 SET status = CASE WHEN status = 'synced' THEN 'changed' ELSE status END,
+	revision = revision + 1,
 	updated_at = ?
 WHERE id = ?
 `
@@ -250,8 +255,8 @@ type MarkWeekPlanEditedParams struct {
 	ID        string
 }
 
-// Records an edit of plan id: a synced plan becomes changed, any other
-// keeps its status.
+// Records an edit of plan id, raising its revision: a synced plan becomes
+// changed, any other keeps its status.
 func (q *Queries) MarkWeekPlanEdited(ctx context.Context, arg MarkWeekPlanEditedParams) error {
 	_, err := q.db.ExecContext(ctx, markWeekPlanEdited, arg.UpdatedAt, arg.ID)
 	return err
@@ -291,7 +296,7 @@ func (q *Queries) PutPlanDay(ctx context.Context, arg PutPlanDayParams) error {
 
 const redraftWeekPlan = `-- name: RedraftWeekPlan :exec
 UPDATE week_plans
-SET status = ?, ai_note = ?, updated_at = ?
+SET status = ?, ai_note = ?, revision = revision + 1, updated_at = ?
 WHERE id = ?
 `
 
@@ -302,7 +307,8 @@ type RedraftWeekPlanParams struct {
 	ID        string
 }
 
-// Records a new draft over plan id: its status and note.
+// Records a new draft over plan id: its status and note, raising its
+// revision.
 func (q *Queries) RedraftWeekPlan(ctx context.Context, arg RedraftWeekPlanParams) error {
 	_, err := q.db.ExecContext(ctx, redraftWeekPlan,
 		arg.Status,

internal/db/querier.go

@@ -69,7 +69,8 @@ type Querier interface {
 	// Returns sql.ErrNoRows until the row exists.
 	GetAISettings(ctx context.Context) (AiSetting, error)
 	// The id of the job of kind queued or running for the week starting
-	// week_start. Returns sql.ErrNoRows when there is none.
+	// week_start, one whose payload has confirm when confirmed is 1. Returns
+	// sql.ErrNoRows when there is none.
 	GetActiveDraftJobID(ctx context.Context, arg GetActiveDraftJobIDParams) (string, error)
 	// The batch still pending or running, oldest first. Returns sql.ErrNoRows
 	// when there is none.
@@ -148,8 +149,8 @@ type Querier interface {
 	// The ids of the dinners planned in the week starting week_start, Monday
 	// first.
 	ListWeekPlanDinnerIDs(ctx context.Context, weekStart string) ([]sql.NullString, error)
-	// Records an edit of plan id: a synced plan becomes changed, any other
-	// keeps its status.
+	// Records an edit of plan id, raising its revision: a synced plan becomes
+	// changed, any other keeps its status.
 	MarkWeekPlanEdited(ctx context.Context, arg MarkWeekPlanEditedParams) error
 	// Moves a dinner still suggested to status (quest_log or archived),
 	// recording updated_by; a dinner no longer suggested is left as it is
@@ -160,7 +161,8 @@ type Querier interface {
 	// Plans dinner_id on date of plan_id, keeping the day's calendar event id
 	// when the day exists.
 	PutPlanDay(ctx context.Context, arg PutPlanDayParams) error
-	// Records a new draft over plan id: its status and note.
+	// Records a new draft over plan id: its status and note, raising its
+	// revision.
 	RedraftWeekPlan(ctx context.Context, arg RedraftWeekPlanParams) error
 	// An unknown id returns sql.ErrNoRows.
 	SetDinnerFavorite(ctx context.Context, arg SetDinnerFavoriteParams) (Dinner, error)