Feat v0.3.1 instance + assignment tables and store

Add workflow execution layer: workflow_instances tracks running workflows
(stage, status, entry token), workflow_assignments tracks per-stage team
queue with optimistic-lock claim. 15 new store methods in PG + SQLite.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/store/postgres/workflows.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 
 	"switchboard-core/models"
+	"switchboard-core/store"
 )
 
 // WorkflowStore implements store.WorkflowStore for Postgres.
@@ -396,8 +397,235 @@ func nullIfEmpty(s string) interface{} {
 	return s
 }
 
-// ── Assignments (v0.29.0-cs3) ───────────────────────────────────────────
+// ── Instances (v0.3.1) ──────────────────────
 
-// ── Lifecycle operations (v0.37.15) ──
+func (s *WorkflowStore) CreateInstance(ctx context.Context, inst *models.WorkflowInstance) error {
+	stageData := jsonOrEmpty(inst.StageData)
+	metadata := jsonOrEmpty(inst.Metadata)
+	status := inst.Status
+	if status == "" {
+		status = models.InstanceStatusActive
+	}
+	return DB.QueryRowContext(ctx, `
+		INSERT INTO workflow_instances (workflow_id, workflow_version, current_stage,
+		            stage_data, status, started_by, entry_token, metadata)
+		VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
+		RETURNING id, stage_entered_at, created_at, updated_at`,
+		inst.WorkflowID, inst.WorkflowVersion, inst.CurrentStage,
+		stageData, status, inst.StartedBy, inst.EntryToken, metadata,
+	).Scan(&inst.ID, &inst.StageEnteredAt, &inst.CreatedAt, &inst.UpdatedAt)
+}
 
-// ── Review Comments (v0.35.0) ───────────────────────────
+func (s *WorkflowStore) GetInstance(ctx context.Context, id string) (*models.WorkflowInstance, error) {
+	inst := &models.WorkflowInstance{}
+	var stageData, metadata []byte
+	err := DB.QueryRowContext(ctx, `
+		SELECT id, workflow_id, workflow_version, current_stage, stage_data,
+		       status, started_by, entry_token, metadata,
+		       stage_entered_at, created_at, updated_at
+		FROM workflow_instances WHERE id = $1`, id,
+	).Scan(&inst.ID, &inst.WorkflowID, &inst.WorkflowVersion, &inst.CurrentStage,
+		&stageData, &inst.Status, &inst.StartedBy, &inst.EntryToken, &metadata,
+		&inst.StageEnteredAt, &inst.CreatedAt, &inst.UpdatedAt)
+	if err != nil {
+		return nil, err
+	}
+	inst.StageData = stageData
+	inst.Metadata = metadata
+	return inst, nil
+}
+
+func (s *WorkflowStore) GetInstanceByToken(ctx context.Context, token string) (*models.WorkflowInstance, error) {
+	inst := &models.WorkflowInstance{}
+	var stageData, metadata []byte
+	err := DB.QueryRowContext(ctx, `
+		SELECT id, workflow_id, workflow_version, current_stage, stage_data,
+		       status, started_by, entry_token, metadata,
+		       stage_entered_at, created_at, updated_at
+		FROM workflow_instances WHERE entry_token = $1`, token,
+	).Scan(&inst.ID, &inst.WorkflowID, &inst.WorkflowVersion, &inst.CurrentStage,
+		&stageData, &inst.Status, &inst.StartedBy, &inst.EntryToken, &metadata,
+		&inst.StageEnteredAt, &inst.CreatedAt, &inst.UpdatedAt)
+	if err != nil {
+		return nil, err
+	}
+	inst.StageData = stageData
+	inst.Metadata = metadata
+	return inst, nil
+}
+
+func (s *WorkflowStore) UpdateInstance(ctx context.Context, inst *models.WorkflowInstance) error {
+	stageData := jsonOrEmpty(inst.StageData)
+	metadata := jsonOrEmpty(inst.Metadata)
+	_, err := DB.ExecContext(ctx, `
+		UPDATE workflow_instances
+		SET current_stage = $2, stage_data = $3, status = $4,
+		    entry_token = $5, metadata = $6, stage_entered_at = $7
+		WHERE id = $1`,
+		inst.ID, inst.CurrentStage, stageData, inst.Status,
+		inst.EntryToken, metadata, inst.StageEnteredAt)
+	return err
+}
+
+func (s *WorkflowStore) ListInstances(ctx context.Context, workflowID string, status string, opts store.ListOptions) ([]models.WorkflowInstance, error) {
+	q := `SELECT id, workflow_id, workflow_version, current_stage, stage_data,
+	             status, started_by, entry_token, metadata,
+	             stage_entered_at, created_at, updated_at
+	      FROM workflow_instances WHERE workflow_id = $1`
+	args := []interface{}{workflowID}
+	idx := 2
+	if status != "" {
+		q += fmt.Sprintf(" AND status = $%d", idx)
+		args = append(args, status)
+		idx++
+	}
+	q += " ORDER BY created_at DESC"
+	if opts.Limit > 0 {
+		q += fmt.Sprintf(" LIMIT $%d", idx)
+		args = append(args, opts.Limit)
+		idx++
+	}
+	if opts.Offset > 0 {
+		q += fmt.Sprintf(" OFFSET $%d", idx)
+		args = append(args, opts.Offset)
+	}
+	rows, err := DB.QueryContext(ctx, q, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var result []models.WorkflowInstance
+	for rows.Next() {
+		var inst models.WorkflowInstance
+		var stageData, metadata []byte
+		if err := rows.Scan(&inst.ID, &inst.WorkflowID, &inst.WorkflowVersion,
+			&inst.CurrentStage, &stageData, &inst.Status, &inst.StartedBy,
+			&inst.EntryToken, &metadata,
+			&inst.StageEnteredAt, &inst.CreatedAt, &inst.UpdatedAt); err != nil {
+			return nil, err
+		}
+		inst.StageData = stageData
+		inst.Metadata = metadata
+		result = append(result, inst)
+	}
+	return result, rows.Err()
+}
+
+func (s *WorkflowStore) AdvanceStage(ctx context.Context, id string, nextStage string, stageData json.RawMessage) error {
+	sd := jsonOrEmpty(stageData)
+	_, err := DB.ExecContext(ctx, `
+		UPDATE workflow_instances
+		SET current_stage = $2, stage_data = $3, stage_entered_at = NOW()
+		WHERE id = $1 AND status = 'active'`,
+		id, nextStage, sd)
+	return err
+}
+
+func (s *WorkflowStore) CompleteInstance(ctx context.Context, id string) error {
+	_, err := DB.ExecContext(ctx, `
+		UPDATE workflow_instances SET status = 'completed' WHERE id = $1 AND status = 'active'`, id)
+	return err
+}
+
+func (s *WorkflowStore) CancelInstance(ctx context.Context, id string) error {
+	_, err := DB.ExecContext(ctx, `
+		UPDATE workflow_instances SET status = 'cancelled' WHERE id = $1 AND status = 'active'`, id)
+	return err
+}
+
+// ── Assignments (v0.3.1) ────────────────────
+
+func (s *WorkflowStore) CreateAssignment(ctx context.Context, a *models.WorkflowAssignment) error {
+	reviewData := jsonOrEmpty(a.ReviewData)
+	status := a.Status
+	if status == "" {
+		status = models.AssignmentStatusUnassigned
+	}
+	return DB.QueryRowContext(ctx, `
+		INSERT INTO workflow_assignments (instance_id, stage, team_id, assigned_to, status, review_data)
+		VALUES ($1, $2, $3, $4, $5, $6)
+		RETURNING id, created_at`,
+		a.InstanceID, a.Stage, a.TeamID, a.AssignedTo, status, reviewData,
+	).Scan(&a.ID, &a.CreatedAt)
+}
+
+func (s *WorkflowStore) ClaimAssignment(ctx context.Context, id string, userID string) error {
+	res, err := DB.ExecContext(ctx, `
+		UPDATE workflow_assignments
+		SET status = 'claimed', assigned_to = $2, claimed_at = NOW()
+		WHERE id = $1 AND status = 'unassigned'`, id, userID)
+	if err != nil {
+		return err
+	}
+	n, _ := res.RowsAffected()
+	if n == 0 {
+		return fmt.Errorf("assignment %s is not claimable", id)
+	}
+	return nil
+}
+
+func (s *WorkflowStore) UnclaimAssignment(ctx context.Context, id string) error {
+	_, err := DB.ExecContext(ctx, `
+		UPDATE workflow_assignments
+		SET status = 'unassigned', assigned_to = NULL, claimed_at = NULL
+		WHERE id = $1 AND status = 'claimed'`, id)
+	return err
+}
+
+func (s *WorkflowStore) CompleteAssignment(ctx context.Context, id string, reviewData json.RawMessage) error {
+	rd := jsonOrEmpty(reviewData)
+	_, err := DB.ExecContext(ctx, `
+		UPDATE workflow_assignments
+		SET status = 'completed', review_data = $2, completed_at = NOW()
+		WHERE id = $1 AND status = 'claimed'`, id, rd)
+	return err
+}
+
+func (s *WorkflowStore) CancelAssignment(ctx context.Context, id string) error {
+	_, err := DB.ExecContext(ctx, `
+		UPDATE workflow_assignments SET status = 'cancelled'
+		WHERE id = $1 AND status IN ('unassigned', 'claimed')`, id)
+	return err
+}
+
+func (s *WorkflowStore) ListAssignmentsByTeam(ctx context.Context, teamID string, status string) ([]models.WorkflowAssignment, error) {
+	q := `SELECT id, instance_id, stage, team_id, assigned_to, status,
+	             review_data, claimed_at, completed_at, created_at
+	      FROM workflow_assignments WHERE team_id = $1`
+	args := []interface{}{teamID}
+	if status != "" {
+		q += " AND status = $2"
+		args = append(args, status)
+	}
+	q += " ORDER BY created_at DESC"
+	return s.queryAssignments(ctx, q, args...)
+}
+
+func (s *WorkflowStore) ListAssignmentsByInstance(ctx context.Context, instanceID string) ([]models.WorkflowAssignment, error) {
+	return s.queryAssignments(ctx, `
+		SELECT id, instance_id, stage, team_id, assigned_to, status,
+		       review_data, claimed_at, completed_at, created_at
+		FROM workflow_assignments WHERE instance_id = $1
+		ORDER BY created_at ASC`, instanceID)
+}
+
+func (s *WorkflowStore) queryAssignments(ctx context.Context, q string, args ...interface{}) ([]models.WorkflowAssignment, error) {
+	rows, err := DB.QueryContext(ctx, q, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var result []models.WorkflowAssignment
+	for rows.Next() {
+		var a models.WorkflowAssignment
+		var reviewData []byte
+		if err := rows.Scan(&a.ID, &a.InstanceID, &a.Stage, &a.TeamID,
+			&a.AssignedTo, &a.Status, &reviewData,
+			&a.ClaimedAt, &a.CompletedAt, &a.CreatedAt); err != nil {
+			return nil, err
+		}
+		a.ReviewData = reviewData
+		result = append(result, a)
+	}
+	return result, rows.Err()
+}