package app

import (
	"context"
	"encoding/json"
	"errors"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgtype"
	"github.com/jackc/pgx/v5/pgxpool"
	goredis "github.com/redis/go-redis/v9"
	"go.uber.org/zap"

	"github.com/geo-platform/tenant-api/internal/shared/auth"
	sharedcache "github.com/geo-platform/tenant-api/internal/shared/cache"
	"github.com/geo-platform/tenant-api/internal/shared/messaging/rabbitmq"
	"github.com/geo-platform/tenant-api/internal/shared/response"
	"github.com/geo-platform/tenant-api/internal/shared/stream"
	"github.com/geo-platform/tenant-api/internal/tenant/repository"
)

type DesktopTaskService struct {
	pool           *pgxpool.Pool
	monitoringPool *pgxpool.Pool
	repo           repository.DesktopTaskRepository
	cache          sharedcache.Cache
	redis          *goredis.Client
	messaging      *rabbitmq.Client
	logger         *zap.Logger
}

func NewDesktopTaskService(pool *pgxpool.Pool, monitoringPool *pgxpool.Pool, messaging *rabbitmq.Client, logger *zap.Logger) *DesktopTaskService {
	return &DesktopTaskService{
		pool:           pool,
		monitoringPool: monitoringPool,
		repo:           repository.NewDesktopTaskRepository(pool),
		messaging:      messaging,
		logger:         logger,
	}
}

func (s *DesktopTaskService) WithCache(c sharedcache.Cache) *DesktopTaskService {
	s.cache = c
	return s
}

func (s *DesktopTaskService) WithRedis(redis *goredis.Client) *DesktopTaskService {
	if s != nil {
		s.redis = redis
	}
	return s
}

type DesktopTaskView struct {
	ID              string          `json:"id"`
	JobID           string          `json:"job_id"`
	TenantID        int64           `json:"tenant_id"`
	WorkspaceID     int64           `json:"workspace_id"`
	TargetAccountID string          `json:"target_account_id"`
	TargetClientID  string          `json:"target_client_id"`
	Platform        string          `json:"platform"`
	Kind            string          `json:"kind"`
	Payload         json.RawMessage `json:"payload"`
	Status          string          `json:"status"`
	DedupKey        *string         `json:"dedup_key"`
	ActiveAttemptID *string         `json:"active_attempt_id"`
	LeaseExpiresAt  *time.Time      `json:"lease_expires_at"`
	Attempts        int             `json:"attempts"`
	Result          json.RawMessage `json:"result"`
	Error           json.RawMessage `json:"error"`
	CreatedAt       time.Time       `json:"created_at"`
	UpdatedAt       time.Time       `json:"updated_at"`
}

type LeaseDesktopTaskRequest struct {
	TaskID *string `json:"task_id"`
	Kind   *string `json:"kind" binding:"omitempty,oneof=publish monitor"`
}

type LeaseDesktopTaskResponse struct {
	Task           *DesktopTaskView `json:"task"`
	AttemptID      *string          `json:"attempt_id,omitempty"`
	LeaseToken     *string          `json:"lease_token,omitempty"`
	LeaseExpiresAt *time.Time       `json:"lease_expires_at,omitempty"`
}

type ExtendDesktopTaskRequest struct {
	LeaseToken string `json:"lease_token" binding:"required"`
}

type CompleteDesktopTaskRequest struct {
	LeaseToken string         `json:"lease_token" binding:"required"`
	Status     string         `json:"status" binding:"required,oneof=succeeded failed unknown"`
	Payload    map[string]any `json:"payload"`
	Error      map[string]any `json:"error"`
}

type CancelDesktopTaskRequest struct {
	LeaseToken *string `json:"lease_token"`
	Reason     *string `json:"reason"`
}

type ReconcileDesktopTaskRequest struct {
	Status string         `json:"status" binding:"required,oneof=succeeded failed aborted retry"`
	Result map[string]any `json:"result"`
	Error  map[string]any `json:"error"`
}

type ListPublishTasksRequest struct {
	Page     int    `form:"page"`
	PageSize int    `form:"page_size"`
	Title    string `form:"title"`
}

type DesktopPublishTaskList struct {
	Items        []DesktopTaskView `json:"items"`
	Page         int               `json:"page"`
	PageSize     int               `json:"page_size"`
	Total        int               `json:"total"`
	PendingCount int               `json:"pending_count"`
	HistoryTotal int               `json:"history_total"`
}

func (s *DesktopTaskService) Lease(ctx context.Context, client *repository.DesktopClient, req LeaseDesktopTaskRequest, routeTaskID *uuid.UUID) (*LeaseDesktopTaskResponse, error) {
	if client == nil {
		return nil, response.ErrUnauthorized(40108, "desktop_client_missing", "desktop client context is required")
	}

	taskID := routeTaskID
	if taskID == nil && req.TaskID != nil && strings.TrimSpace(*req.TaskID) != "" {
		parsed, err := uuid.Parse(strings.TrimSpace(*req.TaskID))
		if err != nil {
			return nil, response.ErrBadRequest(40084, "invalid_desktop_task_id", "task id must be a uuid")
		}
		taskID = &parsed
	}

	if err := s.dropStaleMonitorTasksForClient(ctx, client); err != nil {
		return nil, err
	}
	if err := s.recoverExpiredClientTasks(ctx, client); err != nil {
		return nil, err
	}

	rawToken, tokenHash, err := newDesktopClientToken()
	if err != nil {
		return nil, response.ErrInternal(50087, "desktop_task_lease_token_failed", "failed to generate desktop task lease token")
	}

	attemptID := uuid.New()
	leaseParams := repository.DesktopTaskLeaseParams{
		AttemptID:      attemptID,
		LeaseTokenHash: tokenHash,
	}

	if s.logger != nil {
		fields := []zap.Field{
			zap.String("client_id", client.ID.String()),
		}
		if req.Kind != nil {
			fields = append(fields, zap.String("requested_kind", strings.TrimSpace(*req.Kind)))
		}
		if taskID != nil {
			fields = append(fields, zap.String("task_id", taskID.String()))
		}
		s.logger.Debug("desktop task lease requested", fields...)
	}

	var task *repository.DesktopTask
	switch {
	case taskID != nil:
		task, err = s.leaseQueuedDesktopTaskByID(ctx, client, *taskID, leaseParams)
	case req.Kind != nil && strings.TrimSpace(*req.Kind) == "monitor":
		task, err = s.leaseNextQueuedMonitorTask(ctx, client, leaseParams)
	default:
		task, err = s.repo.LeaseNextQueued(ctx, client.ID, req.Kind, leaseParams)
	}
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			if s.logger != nil {
				fields := []zap.Field{
					zap.String("client_id", client.ID.String()),
				}
				if req.Kind != nil {
					fields = append(fields, zap.String("requested_kind", strings.TrimSpace(*req.Kind)))
				}
				if taskID != nil {
					fields = append(fields, zap.String("task_id", taskID.String()))
				}
				s.logger.Debug("desktop task lease found no matching queued task", fields...)
			}
			if taskID == nil {
				return &LeaseDesktopTaskResponse{}, nil
			}
			return nil, s.classifyLeaseError(ctx, client, taskID)
		}
		return nil, response.ErrInternal(50088, "desktop_task_lease_failed", "failed to lease desktop task")
	}

	if _, attemptErr := s.repo.CreateAttempt(ctx, repository.CreateDesktopTaskAttemptParams{
		DesktopID:      attemptID,
		TaskID:         task.DesktopID,
		ClientID:       client.ID,
		LeaseTokenHash: tokenHash,
	}); attemptErr != nil {
		s.logWarn("desktop task attempt insert failed", attemptErr, zap.String("task_id", task.DesktopID.String()))
	}

	s.publishTaskEvent(ctx, task, "task_leased")

	if s.logger != nil {
		s.logger.Info("desktop task leased",
			zap.String("client_id", client.ID.String()),
			zap.String("task_id", task.DesktopID.String()),
			zap.String("kind", task.Kind),
			zap.String("status", task.Status),
		)
	}

	view := buildDesktopTaskView(task)
	attemptIDText := attemptID.String()
	return &LeaseDesktopTaskResponse{
		Task:           &view,
		AttemptID:      &attemptIDText,
		LeaseToken:     &rawToken,
		LeaseExpiresAt: task.LeaseExpiresAt,
	}, nil
}

const desktopTaskRepositoryReturningColumns = `
	t.desktop_id,
	t.job_id,
	t.tenant_id,
	t.workspace_id,
	t.target_account_id,
	t.target_client_id,
	t.platform_id,
	t.kind,
	t.payload,
	t.status,
	t.priority,
	t.lane,
	t.lane_weight,
	t.source,
	t.scheduler_group_key,
	t.monitor_task_id,
	t.supersedes_task_id,
	t.control_flags,
	t.interrupt_generation,
	t.dedup_key,
	t.active_attempt_id,
	t.lease_expires_at,
	t.attempts,
	t.result,
	t.error,
	t.started_at,
	t.interrupted_at,
	t.interrupt_reason,
	t.enqueued_at,
	t.created_at,
	t.updated_at`

type desktopTaskRepositoryScanner interface {
	Scan(dest ...any) error
}

func (s *DesktopTaskService) leaseNextQueuedMonitorTask(
	ctx context.Context,
	client *repository.DesktopClient,
	params repository.DesktopTaskLeaseParams,
) (*repository.DesktopTask, error) {
	accountIDs, err := s.loadMonitorLeaseAccountIDs(ctx, client)
	if err != nil {
		return nil, err
	}
	hasAccountIDs := len(accountIDs) > 0

	row := s.pool.QueryRow(ctx, `
		WITH candidate AS (
			SELECT dt.desktop_id
			FROM desktop_tasks AS dt
			WHERE dt.tenant_id = $1
			  AND dt.workspace_id = $2
			  AND dt.kind = 'monitor'
			  AND dt.status = 'queued'
			  AND (
				dt.target_client_id = $3
				OR ($4::boolean AND dt.target_account_id = ANY($5::uuid[]))
			  )
			ORDER BY dt.lane_weight DESC,
				dt.priority DESC,
				COALESCE(dt.enqueued_at, dt.created_at) ASC,
				dt.created_at ASC,
				dt.desktop_id ASC
			LIMIT 1
			FOR UPDATE SKIP LOCKED
		)
		UPDATE desktop_tasks AS t
		SET target_client_id = $3,
		    active_attempt_id = $6,
		    lease_token_hash = $7,
		    lease_expires_at = now() + interval '10 minutes',
		    status = 'in_progress',
		    attempts = t.attempts + 1,
		    updated_at = now()
		FROM candidate
		WHERE t.desktop_id = candidate.desktop_id
		RETURNING `+desktopTaskRepositoryReturningColumns,
		client.TenantID,
		client.WorkspaceID,
		client.ID,
		hasAccountIDs,
		accountIDs,
		params.AttemptID,
		params.LeaseTokenHash,
	)
	return scanRepositoryDesktopTask(row)
}

func (s *DesktopTaskService) leaseQueuedDesktopTaskByID(
	ctx context.Context,
	client *repository.DesktopClient,
	desktopID uuid.UUID,
	params repository.DesktopTaskLeaseParams,
) (*repository.DesktopTask, error) {
	accountIDs, err := s.loadMonitorLeaseAccountIDs(ctx, client)
	if err != nil {
		return nil, err
	}
	hasAccountIDs := len(accountIDs) > 0

	row := s.pool.QueryRow(ctx, `
		WITH candidate AS (
			SELECT dt.desktop_id
			FROM desktop_tasks AS dt
			WHERE dt.desktop_id = $1
			  AND dt.workspace_id = $2
			  AND dt.status = 'queued'
			  AND (
				(
					dt.kind = 'monitor'
					AND dt.tenant_id = $3
					AND (
						dt.target_client_id = $4
						OR ($5::boolean AND dt.target_account_id = ANY($6::uuid[]))
					)
				)
				OR (
					dt.kind <> 'monitor'
					AND dt.target_client_id = $4
				)
			  )
			LIMIT 1
			FOR UPDATE SKIP LOCKED
		)
		UPDATE desktop_tasks AS t
		SET target_client_id = CASE WHEN t.kind = 'monitor' THEN $4 ELSE t.target_client_id END,
		    active_attempt_id = $7,
		    lease_token_hash = $8,
		    lease_expires_at = now() + interval '10 minutes',
		    status = 'in_progress',
		    attempts = t.attempts + 1,
		    updated_at = now()
		FROM candidate
		WHERE t.desktop_id = candidate.desktop_id
		RETURNING `+desktopTaskRepositoryReturningColumns,
		desktopID,
		client.WorkspaceID,
		client.TenantID,
		client.ID,
		hasAccountIDs,
		accountIDs,
		params.AttemptID,
		params.LeaseTokenHash,
	)
	return scanRepositoryDesktopTask(row)
}

func (s *DesktopTaskService) loadMonitorLeaseAccountIDs(ctx context.Context, client *repository.DesktopClient) ([]uuid.UUID, error) {
	if s == nil || client == nil || s.pool == nil {
		return nil, nil
	}

	accountIDs := loadTrackedDesktopClientAccountIDs(ctx, s.redis, client.ID)
	rows, err := s.pool.Query(ctx, `
		SELECT desktop_id
		FROM platform_accounts
		WHERE tenant_id = $1
		  AND workspace_id = $2
		  AND client_id = $3
		  AND deleted_at IS NULL
		  AND platform_id = ANY($4::text[])
	`, client.TenantID, client.WorkspaceID, client.ID, monitoringPlatformIDs(defaultMonitoringPlatforms))
	if err != nil {
		return nil, response.ErrInternal(50117, "desktop_account_lookup_failed", "failed to resolve monitor lease accounts")
	}
	defer rows.Close()

	for rows.Next() {
		var accountID uuid.UUID
		if scanErr := rows.Scan(&accountID); scanErr != nil {
			return nil, response.ErrInternal(50117, "desktop_account_lookup_failed", "failed to parse monitor lease accounts")
		}
		accountIDs = append(accountIDs, accountID)
	}
	if err := rows.Err(); err != nil {
		return nil, response.ErrInternal(50117, "desktop_account_lookup_failed", "failed to iterate monitor lease accounts")
	}
	return uniqueUUIDs(accountIDs), nil
}

func scanRepositoryDesktopTask(row desktopTaskRepositoryScanner) (*repository.DesktopTask, error) {
	var (
		task              repository.DesktopTask
		schedulerGroupKey pgtype.Text
		monitorTaskID     pgtype.Int8
		supersedesTaskID  pgtype.UUID
		dedupKey          pgtype.Text
		activeAttemptID   pgtype.UUID
		leaseExpiresAt    pgtype.Timestamptz
		startedAt         pgtype.Timestamptz
		interruptedAt     pgtype.Timestamptz
		interruptReason   pgtype.Text
		enqueuedAt        pgtype.Timestamptz
	)
	if err := row.Scan(
		&task.DesktopID,
		&task.JobID,
		&task.TenantID,
		&task.WorkspaceID,
		&task.TargetAccountID,
		&task.TargetClientID,
		&task.Platform,
		&task.Kind,
		&task.Payload,
		&task.Status,
		&task.Priority,
		&task.Lane,
		&task.LaneWeight,
		&task.Source,
		&schedulerGroupKey,
		&monitorTaskID,
		&supersedesTaskID,
		&task.ControlFlags,
		&task.InterruptGeneration,
		&dedupKey,
		&activeAttemptID,
		&leaseExpiresAt,
		&task.Attempts,
		&task.Result,
		&task.Error,
		&startedAt,
		&interruptedAt,
		&interruptReason,
		&enqueuedAt,
		&task.CreatedAt,
		&task.UpdatedAt,
	); err != nil {
		return nil, err
	}

	task.SchedulerGroupKey = desktopTaskNullableText(schedulerGroupKey)
	task.MonitorTaskID = desktopTaskNullableInt64(monitorTaskID)
	task.SupersedesTaskID = desktopTaskNullableUUID(supersedesTaskID)
	task.DedupKey = desktopTaskNullableText(dedupKey)
	task.ActiveAttemptID = desktopTaskNullableUUID(activeAttemptID)
	task.LeaseExpiresAt = desktopTaskNullableTime(leaseExpiresAt)
	task.StartedAt = desktopTaskNullableTime(startedAt)
	task.InterruptedAt = desktopTaskNullableTime(interruptedAt)
	task.InterruptReason = desktopTaskNullableText(interruptReason)
	if enqueuedAt.Valid {
		task.EnqueuedAt = enqueuedAt.Time
	}
	return &task, nil
}

func desktopTaskNullableText(value pgtype.Text) *string {
	if !value.Valid {
		return nil
	}
	text := value.String
	return &text
}

func desktopTaskNullableInt64(value pgtype.Int8) *int64 {
	if !value.Valid {
		return nil
	}
	number := value.Int64
	return &number
}

func desktopTaskNullableUUID(value pgtype.UUID) *uuid.UUID {
	if !value.Valid {
		return nil
	}
	resolved, err := uuid.FromBytes(value.Bytes[:])
	if err != nil {
		return nil
	}
	return &resolved
}

func desktopTaskNullableTime(value pgtype.Timestamptz) *time.Time {
	if !value.Valid {
		return nil
	}
	timestamp := value.Time
	return &timestamp
}

func (s *DesktopTaskService) Extend(ctx context.Context, client *repository.DesktopClient, desktopID uuid.UUID, req ExtendDesktopTaskRequest) (*DesktopTaskView, error) {
	if client == nil {
		return nil, response.ErrUnauthorized(40108, "desktop_client_missing", "desktop client context is required")
	}

	if err := s.dropStaleMonitorTasksForClient(ctx, client); err != nil {
		return nil, err
	}

	task, err := s.repo.ExtendLease(ctx, desktopID, HashDesktopClientToken(strings.TrimSpace(req.LeaseToken)))
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, response.ErrConflict(40983, "desktop_task_lease_invalid", "desktop task lease token is invalid or expired")
		}
		return nil, response.ErrInternal(50089, "desktop_task_extend_failed", "failed to extend desktop task lease")
	}

	s.publishTaskEvent(ctx, task, "task_extended")

	view := buildDesktopTaskView(task)
	return &view, nil
}

func (s *DesktopTaskService) Complete(ctx context.Context, client *repository.DesktopClient, desktopID uuid.UUID, req CompleteDesktopTaskRequest) (*DesktopTaskView, error) {
	if client == nil {
		return nil, response.ErrUnauthorized(40108, "desktop_client_missing", "desktop client context is required")
	}

	finalStatus := normalizeDesktopTaskTerminalStatus(req.Status)
	resultJSON, err := marshalOptionalJSON(req.Payload)
	if err != nil {
		return nil, response.ErrBadRequest(40086, "invalid_desktop_task_payload", "payload must be serializable")
	}
	errorJSON, err := marshalOptionalJSON(req.Error)
	if err != nil {
		return nil, response.ErrBadRequest(40087, "invalid_desktop_task_error", "error must be serializable")
	}

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return nil, response.ErrInternal(50103, "desktop_task_complete_begin_failed", "failed to start desktop task completion")
	}
	defer tx.Rollback(ctx)

	taskRepo := repository.NewDesktopTaskRepository(tx)
	previousTask, _ := taskRepo.GetByDesktopID(ctx, desktopID, client.WorkspaceID)
	previousAttemptID := activeAttemptID(previousTask)

	task, err := taskRepo.Complete(ctx, desktopID, HashDesktopClientToken(strings.TrimSpace(req.LeaseToken)), finalStatus, resultJSON, errorJSON)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, response.ErrConflict(40983, "desktop_task_lease_invalid", "desktop task lease token is invalid or expired")
		}
		return nil, response.ErrInternal(50091, "desktop_task_complete_failed", "failed to complete desktop task")
	}

	if previousAttemptID != nil {
		if finishErr := taskRepo.FinishAttempt(ctx, repository.FinishDesktopTaskAttemptParams{
			TaskID:      task.DesktopID,
			AttemptID:   *previousAttemptID,
			FinalStatus: &finalStatus,
			Error:       errorJSON,
		}); finishErr != nil {
			s.logWarn("desktop task attempt finish failed after complete", finishErr, zap.String("task_id", task.DesktopID.String()))
		}
	}

	publishOutcome, err := syncDesktopPublishTaskState(ctx, tx, task)
	if err != nil {
		return nil, err
	}

	if err := tx.Commit(ctx); err != nil {
		return nil, response.ErrInternal(50104, "desktop_task_complete_commit_failed", "failed to commit desktop task completion")
	}

	if publishOutcome != nil {
		invalidateArticleCaches(ctx, s.cache, publishOutcome.TenantID, &publishOutcome.ArticleID)
		if syncErr := s.syncMonitoringArticleAlias(ctx, publishOutcome.ArticleAlias); syncErr != nil {
			s.logWarn("monitoring article alias sync failed after publish complete", syncErr, zap.Int64("article_id", publishOutcome.ArticleID))
		}
	}

	s.publishTaskEvent(ctx, task, "task_completed")

	view := buildDesktopTaskView(task)
	return &view, nil
}

func (s *DesktopTaskService) Cancel(ctx context.Context, client *repository.DesktopClient, desktopID uuid.UUID, req CancelDesktopTaskRequest) (*DesktopTaskView, error) {
	if client == nil {
		return nil, response.ErrUnauthorized(40108, "desktop_client_missing", "desktop client context is required")
	}

	errorJSON, err := marshalOptionalJSON(map[string]any{
		"reason": optionalStringValue(req.Reason),
		"source": "desktop_client",
	})
	if err != nil {
		return nil, response.ErrBadRequest(40088, "invalid_desktop_task_cancel", "cancel payload must be serializable")
	}

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return nil, response.ErrInternal(50107, "desktop_task_cancel_begin_failed", "failed to start desktop task cancel")
	}
	defer tx.Rollback(ctx)

	taskRepo := repository.NewDesktopTaskRepository(tx)
	previousTask, _ := taskRepo.GetByDesktopID(ctx, desktopID, client.WorkspaceID)
	previousAttemptID := activeAttemptID(previousTask)

	var task *repository.DesktopTask
	if req.LeaseToken != nil && strings.TrimSpace(*req.LeaseToken) != "" {
		task, err = taskRepo.CancelByLease(ctx, desktopID, HashDesktopClientToken(strings.TrimSpace(*req.LeaseToken)), errorJSON)
	} else {
		task, err = taskRepo.CancelByClient(ctx, desktopID, client.ID, errorJSON)
	}
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, response.ErrConflict(40984, "desktop_task_cancel_conflict", "desktop task cannot be canceled in its current state")
		}
		return nil, response.ErrInternal(50092, "desktop_task_cancel_failed", "failed to cancel desktop task")
	}

	if previousAttemptID != nil && req.LeaseToken != nil && strings.TrimSpace(*req.LeaseToken) != "" {
		if finishErr := taskRepo.FinishAttempt(ctx, repository.FinishDesktopTaskAttemptParams{
			TaskID:      task.DesktopID,
			AttemptID:   *previousAttemptID,
			FinalStatus: literalStringPtr("aborted"),
			Error:       errorJSON,
		}); finishErr != nil {
			s.logWarn("desktop task attempt finish failed after cancel", finishErr, zap.String("task_id", task.DesktopID.String()))
		}
	}

	var replacementTask *repository.DesktopTask
	if shouldRequeuePreemptedMonitorTask(task, req.Reason) {
		replacementTask, err = requeuePreemptedMonitorTask(ctx, tx, taskRepo, task)
		if err != nil {
			return nil, err
		}
	}

	if err := tx.Commit(ctx); err != nil {
		return nil, response.ErrInternal(50108, "desktop_task_cancel_commit_failed", "failed to commit desktop task cancel")
	}

	s.publishTaskEvent(ctx, task, "task_canceled")
	if replacementTask != nil {
		s.publishTaskEvent(ctx, replacementTask, "task_available")
	}

	view := buildDesktopTaskView(task)
	return &view, nil
}

func (s *DesktopTaskService) TenantCancel(ctx context.Context, actor auth.Actor, desktopID uuid.UUID, req CancelDesktopTaskRequest) (*DesktopTaskView, error) {
	if actor.PrimaryWorkspaceID == 0 {
		return nil, response.ErrUnauthorized(40132, "workspace_scope_missing", "workspace context is required")
	}

	errorJSON, err := marshalOptionalJSON(map[string]any{
		"reason": optionalStringValue(req.Reason),
		"source": "tenant_web",
	})
	if err != nil {
		return nil, response.ErrBadRequest(40088, "invalid_desktop_task_cancel", "cancel payload must be serializable")
	}

	task, err := s.repo.TenantCancel(ctx, desktopID, actor.PrimaryWorkspaceID, errorJSON)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, response.ErrConflict(40984, "desktop_task_cancel_conflict", "desktop task cannot be canceled in its current state")
		}
		return nil, response.ErrInternal(50093, "desktop_task_tenant_cancel_failed", "failed to cancel desktop task")
	}

	s.publishTaskEvent(ctx, task, "task_canceled")

	view := buildDesktopTaskView(task)
	return &view, nil
}

func (s *DesktopTaskService) Reconcile(ctx context.Context, actor auth.Actor, desktopID uuid.UUID, req ReconcileDesktopTaskRequest) (*DesktopTaskView, error) {
	if actor.PrimaryWorkspaceID == 0 {
		return nil, response.ErrUnauthorized(40132, "workspace_scope_missing", "workspace context is required")
	}

	resultJSON, err := marshalOptionalJSON(req.Result)
	if err != nil {
		return nil, response.ErrBadRequest(40089, "invalid_desktop_task_reconcile_result", "result must be serializable")
	}
	errorJSON, err := marshalOptionalJSON(req.Error)
	if err != nil {
		return nil, response.ErrBadRequest(40090, "invalid_desktop_task_reconcile_error", "error must be serializable")
	}

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return nil, response.ErrInternal(50105, "desktop_task_reconcile_begin_failed", "failed to start desktop task reconcile")
	}
	defer tx.Rollback(ctx)

	taskRepo := repository.NewDesktopTaskRepository(tx)
	task, err := taskRepo.Reconcile(ctx, desktopID, actor.PrimaryWorkspaceID, req.Status, resultJSON, errorJSON)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, response.ErrConflict(40985, "desktop_task_reconcile_conflict", "desktop task is not waiting for reconcile")
		}
		return nil, response.ErrInternal(50094, "desktop_task_reconcile_failed", "failed to reconcile desktop task")
	}

	publishOutcome, err := syncDesktopPublishTaskState(ctx, tx, task)
	if err != nil {
		return nil, err
	}

	if err := tx.Commit(ctx); err != nil {
		return nil, response.ErrInternal(50106, "desktop_task_reconcile_commit_failed", "failed to commit desktop task reconcile")
	}

	if publishOutcome != nil {
		invalidateArticleCaches(ctx, s.cache, publishOutcome.TenantID, &publishOutcome.ArticleID)
		if syncErr := s.syncMonitoringArticleAlias(ctx, publishOutcome.ArticleAlias); syncErr != nil {
			s.logWarn("monitoring article alias sync failed after publish reconcile", syncErr, zap.Int64("article_id", publishOutcome.ArticleID))
		}
	}

	eventType := "task_reconciled"
	if task.Kind == "monitor" && req.Status == "retry" {
		eventType = "task_available"
	}
	s.publishTaskEvent(ctx, task, eventType)

	view := buildDesktopTaskView(task)
	return &view, nil
}

func (s *DesktopTaskService) ListPublishTasks(ctx context.Context, client *repository.DesktopClient, req ListPublishTasksRequest) (*DesktopPublishTaskList, error) {
	if client == nil {
		return nil, response.ErrUnauthorized(40108, "desktop_client_missing", "desktop client context is required")
	}
	if s.pool == nil {
		return nil, response.ErrServiceUnavailable(50342, "desktop_publish_job_store_unavailable", "desktop publish job store is unavailable")
	}

	page := req.Page
	if page <= 0 {
		page = 1
	}
	pageSize := req.PageSize
	if pageSize <= 0 || pageSize > 50 {
		pageSize = 10
	}

	title := strings.TrimSpace(req.Title)
	pendingStatuses := []string{"queued", "in_progress"}
	historyStatuses := []string{"succeeded", "failed", "unknown", "aborted"}

	pendingItems, err := s.listPublishTasksByStatuses(
		ctx,
		client,
		pendingStatuses,
		title,
		0,
		0,
		`CASE WHEN t.status = 'in_progress' THEN 0 ELSE 1 END ASC, t.created_at ASC, t.desktop_id DESC`,
	)
	if err != nil {
		return nil, err
	}

	historyTotal, err := s.countPublishTasksByStatuses(ctx, client, historyStatuses, title)
	if err != nil {
		return nil, err
	}

	offset := (page - 1) * pageSize
	items := make([]DesktopTaskView, 0, pageSize)
	total := len(pendingItems) + historyTotal

	if offset < len(pendingItems) {
		end := offset + pageSize
		if end > len(pendingItems) {
			end = len(pendingItems)
		}
		items = append(items, pendingItems[offset:end]...)
	}

	remaining := pageSize - len(items)
	historyOffset := offset - len(pendingItems)
	if historyOffset < 0 {
		historyOffset = 0
	}

	if remaining > 0 && historyOffset < historyTotal {
		historyItems, listErr := s.listPublishTasksByStatuses(
			ctx,
			client,
			historyStatuses,
			title,
			remaining,
			historyOffset,
			`t.updated_at DESC, t.desktop_id DESC`,
		)
		if listErr != nil {
			return nil, listErr
		}
		items = append(items, historyItems...)
	}

	return &DesktopPublishTaskList{
		Items:        items,
		Page:         page,
		PageSize:     pageSize,
		Total:        total,
		PendingCount: len(pendingItems),
		HistoryTotal: historyTotal,
	}, nil
}

func (s *DesktopTaskService) listPublishTasksByStatuses(
	ctx context.Context,
	client *repository.DesktopClient,
	statuses []string,
	title string,
	limit int,
	offset int,
	orderBy string,
) ([]DesktopTaskView, error) {
	query := `
		SELECT
			t.desktop_id,
			t.job_id,
			t.tenant_id,
			t.workspace_id,
			t.target_account_id,
			t.target_client_id,
			t.platform_id,
			t.kind,
			t.payload,
			t.status,
			t.dedup_key,
			t.active_attempt_id,
			t.lease_expires_at,
			t.attempts,
			t.result,
			t.error,
			t.created_at,
			t.updated_at
		FROM desktop_tasks AS t
		JOIN desktop_publish_jobs AS j
		  ON j.desktop_id = t.job_id
		 AND j.workspace_id = t.workspace_id
		WHERE t.workspace_id = $1
		  AND j.created_by_user_id = $2
		  AND t.kind = 'publish'
		  AND t.status = ANY($3)
		  AND (
		    $4 = ''
		    OR COALESCE(t.payload->>'title', j.title, '') ILIKE '%' || $4 || '%'
		  )
	`
	args := []any{client.WorkspaceID, client.UserID, statuses, title}

	if strings.TrimSpace(orderBy) != "" {
		query += "\nORDER BY " + orderBy
	}
	if limit > 0 {
		query += "\nLIMIT $5 OFFSET $6"
		args = append(args, limit, offset)
	}

	rows, err := s.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, response.ErrInternal(50109, "desktop_publish_tasks_query_failed", "failed to list desktop publish tasks")
	}
	defer rows.Close()

	return scanDesktopTaskRows(rows)
}

func (s *DesktopTaskService) countPublishTasksByStatuses(
	ctx context.Context,
	client *repository.DesktopClient,
	statuses []string,
	title string,
) (int, error) {
	var count int
	err := s.pool.QueryRow(ctx, `
		SELECT COUNT(1)
		FROM desktop_tasks AS t
		JOIN desktop_publish_jobs AS j
		  ON j.desktop_id = t.job_id
		 AND j.workspace_id = t.workspace_id
		WHERE t.workspace_id = $1
		  AND j.created_by_user_id = $2
		  AND t.kind = 'publish'
		  AND t.status = ANY($3)
		  AND (
		    $4 = ''
		    OR COALESCE(t.payload->>'title', j.title, '') ILIKE '%' || $4 || '%'
		  )
	`, client.WorkspaceID, client.UserID, statuses, title).Scan(&count)
	if err != nil {
		return 0, response.ErrInternal(50109, "desktop_publish_tasks_query_failed", "failed to list desktop publish tasks")
	}
	return count, nil
}

func scanDesktopTaskRows(rows pgx.Rows) ([]DesktopTaskView, error) {
	items := make([]DesktopTaskView, 0)
	for rows.Next() {
		var (
			desktopID       uuid.UUID
			jobID           uuid.UUID
			tenantID        int64
			workspaceID     int64
			targetAccountID uuid.UUID
			targetClientID  uuid.UUID
			platform        string
			kind            string
			payload         []byte
			status          string
			dedupKey        pgtype.Text
			activeAttemptID pgtype.UUID
			leaseExpiresAt  pgtype.Timestamptz
			attempts        int32
			resultJSON      []byte
			errorJSON       []byte
			createdAt       time.Time
			updatedAt       time.Time
		)
		if err := rows.Scan(
			&desktopID,
			&jobID,
			&tenantID,
			&workspaceID,
			&targetAccountID,
			&targetClientID,
			&platform,
			&kind,
			&payload,
			&status,
			&dedupKey,
			&activeAttemptID,
			&leaseExpiresAt,
			&attempts,
			&resultJSON,
			&errorJSON,
			&createdAt,
			&updatedAt,
		); err != nil {
			return nil, response.ErrInternal(50110, "desktop_publish_tasks_scan_failed", "failed to scan desktop publish tasks")
		}

		var dedupKeyText *string
		if dedupKey.Valid {
			value := dedupKey.String
			dedupKeyText = &value
		}

		var activeAttemptIDText *string
		if activeAttemptID.Valid {
			value, convErr := uuid.FromBytes(activeAttemptID.Bytes[:])
			if convErr == nil {
				text := value.String()
				activeAttemptIDText = &text
			}
		}

		var leaseExpiresAtValue *time.Time
		if leaseExpiresAt.Valid {
			value := leaseExpiresAt.Time
			leaseExpiresAtValue = &value
		}

		items = append(items, DesktopTaskView{
			ID:              desktopID.String(),
			JobID:           jobID.String(),
			TenantID:        tenantID,
			WorkspaceID:     workspaceID,
			TargetAccountID: targetAccountID.String(),
			TargetClientID:  targetClientID.String(),
			Platform:        platform,
			Kind:            kind,
			Payload:         json.RawMessage(payload),
			Status:          normalizeDesktopTaskTerminalStatus(status),
			DedupKey:        dedupKeyText,
			ActiveAttemptID: activeAttemptIDText,
			LeaseExpiresAt:  leaseExpiresAtValue,
			Attempts:        int(attempts),
			Result:          json.RawMessage(resultJSON),
			Error:           json.RawMessage(errorJSON),
			CreatedAt:       createdAt,
			UpdatedAt:       updatedAt,
		})
	}
	if err := rows.Err(); err != nil {
		return nil, response.ErrInternal(50109, "desktop_publish_tasks_query_failed", "failed to list desktop publish tasks")
	}
	return items, nil
}

func (s *DesktopTaskService) classifyLeaseError(ctx context.Context, client *repository.DesktopClient, taskID *uuid.UUID) error {
	if taskID == nil {
		return response.ErrConflict(40986, "desktop_task_unavailable", "no desktop task is currently available")
	}

	task, err := s.repo.GetByDesktopID(ctx, *taskID, client.WorkspaceID)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return response.ErrNotFound(40482, "desktop_task_not_found", "desktop task not found")
		}
		return response.ErrInternal(50095, "desktop_task_lookup_failed", "failed to inspect desktop task state")
	}

	if task.TargetClientID != client.ID && !s.clientCanLeaseMonitorTask(ctx, client, task) {
		return response.ErrForbidden(40381, "desktop_task_not_target_client", "desktop task is assigned to another desktop client")
	}

	if task.Status == "in_progress" {
		return response.ErrConflict(40989, "desktop_task_already_in_progress", "desktop task is already in progress")
	}

	return response.ErrConflict(40991, "desktop_task_not_queued", "desktop task is not queued")
}

func (s *DesktopTaskService) clientCanLeaseMonitorTask(ctx context.Context, client *repository.DesktopClient, task *repository.DesktopTask) bool {
	if s == nil || client == nil || task == nil || task.Kind != "monitor" || task.TargetAccountID == uuid.Nil {
		return false
	}
	accountIDs, err := s.loadMonitorLeaseAccountIDs(ctx, client)
	if err != nil {
		return false
	}
	for _, accountID := range accountIDs {
		if accountID == task.TargetAccountID {
			return true
		}
	}
	return false
}

func buildDesktopTaskView(task *repository.DesktopTask) DesktopTaskView {
	var activeAttemptID *string
	if task.ActiveAttemptID != nil {
		value := task.ActiveAttemptID.String()
		activeAttemptID = &value
	}

	return DesktopTaskView{
		ID:              task.DesktopID.String(),
		JobID:           task.JobID.String(),
		TenantID:        task.TenantID,
		WorkspaceID:     task.WorkspaceID,
		TargetAccountID: task.TargetAccountID.String(),
		TargetClientID:  task.TargetClientID.String(),
		Platform:        task.Platform,
		Kind:            task.Kind,
		Payload:         json.RawMessage(task.Payload),
		Status:          normalizeDesktopTaskTerminalStatus(task.Status),
		DedupKey:        task.DedupKey,
		ActiveAttemptID: activeAttemptID,
		LeaseExpiresAt:  task.LeaseExpiresAt,
		Attempts:        task.Attempts,
		Result:          json.RawMessage(task.Result),
		Error:           json.RawMessage(task.Error),
		CreatedAt:       task.CreatedAt,
		UpdatedAt:       task.UpdatedAt,
	}
}

func marshalOptionalJSON(value any) ([]byte, error) {
	if value == nil {
		return nil, nil
	}
	return json.Marshal(value)
}

func optionalStringValue(value *string) string {
	if value == nil {
		return ""
	}
	return strings.TrimSpace(*value)
}

func literalStringPtr(value string) *string {
	return &value
}

func normalizeDesktopTaskTerminalStatus(status string) string {
	switch strings.TrimSpace(status) {
	case "unknown":
		return "failed"
	default:
		return strings.TrimSpace(status)
	}
}

type desktopTaskRecoveryMode string

const (
	desktopTaskRecoveryModeStartup     desktopTaskRecoveryMode = "startup"
	desktopTaskRecoveryModeDisconnect  desktopTaskRecoveryMode = "disconnect"
	desktopTaskRecoveryModeLeaseExpiry desktopTaskRecoveryMode = "lease_expired"
)

type recoveredDesktopTaskLease struct {
	TaskID        uuid.UUID
	WorkspaceID   int64
	Kind          string
	Status        string
	ActiveAttempt pgtype.UUID
}

func (s *DesktopTaskService) recoverClientTasksOnStartup(ctx context.Context, client *repository.DesktopClient) error {
	return s.recoverClientTasks(ctx, client, desktopTaskRecoveryModeStartup)
}

func (s *DesktopTaskService) recoverClientTasksOnDisconnect(ctx context.Context, client *repository.DesktopClient) error {
	return s.recoverClientTasks(ctx, client, desktopTaskRecoveryModeDisconnect)
}

func (s *DesktopTaskService) recoverExpiredClientTasks(ctx context.Context, client *repository.DesktopClient) error {
	return s.recoverClientTasks(ctx, client, desktopTaskRecoveryModeLeaseExpiry)
}

func (s *DesktopTaskService) recoverClientTasks(
	ctx context.Context,
	client *repository.DesktopClient,
	mode desktopTaskRecoveryMode,
) error {
	if s == nil || client == nil || s.pool == nil {
		return nil
	}

	publishErrorJSON, publishReason, publishMessage, err := desktopTaskRecoveryPayload(mode, "publish")
	if err != nil {
		return response.ErrInternal(50195, "desktop_task_recovery_payload_failed", "failed to encode publish desktop task recovery payload")
	}
	monitorErrorJSON, monitorReason, _, err := desktopTaskRecoveryPayload(mode, "monitor")
	if err != nil {
		return response.ErrInternal(50195, "desktop_task_recovery_payload_failed", "failed to encode monitor desktop task recovery payload")
	}

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return response.ErrInternal(50196, "desktop_task_recovery_begin_failed", "failed to start desktop task recovery")
	}
	defer tx.Rollback(ctx)

	repo := repository.NewDesktopTaskRepository(tx)
	query := `
		SELECT
			desktop_id,
			workspace_id,
			kind,
			active_attempt_id
		FROM desktop_tasks
		WHERE target_client_id = $1
		  AND workspace_id = $2
		  AND status = 'in_progress'
	`
	queryArgs := []any{client.ID, client.WorkspaceID}
	if mode == desktopTaskRecoveryModeLeaseExpiry {
		query += `
		  AND lease_expires_at IS NOT NULL
		  AND lease_expires_at < NOW()
		`
	}
	query += `
		FOR UPDATE
	`

	rows, err := tx.Query(ctx, query, queryArgs...)
	if err != nil {
		s.logWarn("desktop task recovery query failed", err, zap.String("client_id", client.ID.String()), zap.String("mode", string(mode)))
		return response.ErrInternal(50197, "desktop_task_recovery_query_failed", "failed to select recoverable desktop tasks")
	}
	defer rows.Close()

	recovered := make([]recoveredDesktopTaskLease, 0)
	for rows.Next() {
		var item recoveredDesktopTaskLease
		if scanErr := rows.Scan(
			&item.TaskID,
			&item.WorkspaceID,
			&item.Kind,
			&item.Status,
			&item.ActiveAttempt,
		); scanErr != nil {
			return response.ErrInternal(50198, "desktop_task_recovery_scan_failed", "failed to parse recovered desktop tasks")
		}
		recovered = append(recovered, item)
	}
	if err := rows.Err(); err != nil {
		return response.ErrInternal(50198, "desktop_task_recovery_scan_failed", "failed to iterate recovered desktop tasks")
	}

	for index := range recovered {
		item := &recovered[index]
		if item.Kind == "monitor" {
			if _, execErr := tx.Exec(ctx, `
				UPDATE desktop_tasks
				SET status = 'queued',
				    error = $2,
				    active_attempt_id = NULL,
				    lease_token_hash = NULL,
				    lease_expires_at = NULL,
				    interrupted_at = COALESCE(interrupted_at, NOW()),
				    interrupt_reason = $3,
				    enqueued_at = NOW(),
				    updated_at = NOW()
				WHERE desktop_id = $1
			`, item.TaskID, monitorErrorJSON, monitorReason); execErr != nil {
				s.logWarn("desktop monitor task recovery update failed", execErr, zap.String("task_id", item.TaskID.String()), zap.String("mode", string(mode)))
				return response.ErrInternal(50197, "desktop_task_recovery_query_failed", "failed to select recoverable desktop tasks")
			}
			item.Status = "queued"
			continue
		}

		if _, execErr := tx.Exec(ctx, `
			UPDATE desktop_tasks
			SET status = 'unknown',
			    error = $2,
			    active_attempt_id = NULL,
			    lease_token_hash = NULL,
			    lease_expires_at = NULL,
			    interrupted_at = COALESCE(interrupted_at, NOW()),
			    interrupt_reason = COALESCE(interrupt_reason, $3),
			    updated_at = NOW()
			WHERE desktop_id = $1
		`, item.TaskID, publishErrorJSON, publishReason); execErr != nil {
			s.logWarn("desktop publish task recovery update failed", execErr, zap.String("task_id", item.TaskID.String()), zap.String("mode", string(mode)))
			return response.ErrInternal(50197, "desktop_task_recovery_query_failed", "failed to select recoverable desktop tasks")
		}
		item.Status = "unknown"
	}

	for _, item := range recovered {
		if !item.ActiveAttempt.Valid {
			continue
		}

		attemptID, convErr := uuid.FromBytes(item.ActiveAttempt.Bytes[:])
		if convErr != nil {
			s.logWarn("desktop recovery attempt id decode failed", convErr, zap.String("task_id", item.TaskID.String()))
			continue
		}

		finalStatus := literalStringPtr(item.Status)
		errorJSON := publishErrorJSON
		if item.Kind == "monitor" {
			finalStatus = literalStringPtr("aborted")
			errorJSON = monitorErrorJSON
		}

		if finishErr := repo.FinishAttempt(ctx, repository.FinishDesktopTaskAttemptParams{
			TaskID:      item.TaskID,
			AttemptID:   attemptID,
			FinalStatus: finalStatus,
			Error:       errorJSON,
		}); finishErr != nil {
			s.logWarn("desktop recovery attempt finish failed", finishErr, zap.String("task_id", item.TaskID.String()))
		}
	}

	if err := tx.Commit(ctx); err != nil {
		return response.ErrInternal(50199, "desktop_task_recovery_commit_failed", "failed to commit desktop task recovery")
	}

	for _, item := range recovered {
		task, getErr := s.repo.GetByDesktopID(ctx, item.TaskID, item.WorkspaceID)
		if getErr != nil {
			s.logWarn("desktop recovery reload failed", getErr, zap.String("task_id", item.TaskID.String()))
			continue
		}

		eventType := "task_completed"
		if item.Kind == "monitor" {
			eventType = "task_available"
		}
		s.publishTaskEvent(ctx, task, eventType)
	}

	if len(recovered) > 0 && s.logger != nil {
		s.logger.Info("desktop tasks recovered",
			zap.String("client_id", client.ID.String()),
			zap.String("mode", string(mode)),
			zap.Int("count", len(recovered)),
			zap.String("publish_message", publishMessage),
		)
	}

	return nil
}

func desktopTaskRecoveryPayload(mode desktopTaskRecoveryMode, kind string) ([]byte, string, string, error) {
	reason := strings.TrimSpace(string(mode))
	message := "desktop task was recovered after the client lost the active lease"
	source := "desktop_task_recovery"

	switch mode {
	case desktopTaskRecoveryModeStartup:
		source = "desktop_client_startup"
		if kind == "monitor" {
			message = "desktop client restarted while the monitor task was in progress; task has been re-queued"
		} else {
			message = "desktop client restarted while the publish task was in progress; task has been moved to unknown for manual reconcile"
		}
	case desktopTaskRecoveryModeDisconnect:
		source = "desktop_client_offline"
		if kind == "monitor" {
			message = "desktop client went offline while the monitor task was in progress; task has been re-queued"
		} else {
			message = "desktop client went offline while the publish task was in progress; task has been moved to unknown for manual reconcile"
		}
	case desktopTaskRecoveryModeLeaseExpiry:
		source = "desktop_task_lease_expiry"
		if kind == "monitor" {
			message = "desktop task lease expired before monitor completion; task has been re-queued"
		} else {
			message = "desktop task lease expired before publish completion; task has been moved to unknown for manual reconcile"
		}
	}

	payload, err := marshalOptionalJSON(map[string]any{
		"reason":  reason,
		"message": message,
		"source":  source,
	})
	if err != nil {
		return nil, "", "", err
	}
	return payload, reason, message, nil
}

func (s *DesktopTaskService) dropStaleMonitorTasksForClient(ctx context.Context, client *repository.DesktopClient) error {
	if s == nil || client == nil || s.pool == nil || s.monitoringPool == nil {
		return nil
	}

	_, currentBusinessDate := monitoringBusinessDayAndDateAt(time.Now())
	errorJSON, err := marshalOptionalJSON(map[string]any{
		"reason":                monitoringStaleTaskDropReason,
		"message":               monitoringStaleTaskDropError,
		"current_business_date": currentBusinessDate,
		"source":                "business_day_rollover",
	})
	if err != nil {
		return response.ErrInternal(50190, "desktop_task_stale_payload_failed", "failed to encode stale monitor desktop task payload")
	}

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return response.ErrInternal(50191, "desktop_task_stale_begin_failed", "failed to start stale monitor desktop cleanup")
	}
	defer tx.Rollback(ctx)

	rows, err := tx.Query(ctx, `
		WITH stale AS (
			SELECT
				desktop_id,
				active_attempt_id
			FROM desktop_tasks
			WHERE target_client_id = $1
			  AND kind = 'monitor'
			  AND status IN ('queued', 'in_progress', 'unknown')
			  AND COALESCE(
				NULLIF(payload ->> 'business_date', ''),
				NULLIF(payload ->> 'businessDate', ''),
				NULLIF(payload ->> 'metric_date', ''),
				NULLIF(payload ->> 'date', '')
			  ) < $2
			FOR UPDATE
		),
		updated AS (
			UPDATE desktop_tasks AS t
			SET status = 'aborted',
			    error = $3,
			    active_attempt_id = NULL,
			    lease_token_hash = NULL,
			    lease_expires_at = NULL,
			    interrupted_at = COALESCE(interrupted_at, NOW()),
			    interrupt_reason = $4,
			    updated_at = NOW()
			FROM stale
			WHERE t.desktop_id = stale.desktop_id
			RETURNING t.desktop_id
		)
		SELECT stale.desktop_id, stale.active_attempt_id
		FROM stale
		INNER JOIN updated ON updated.desktop_id = stale.desktop_id
	`, client.ID, currentBusinessDate, errorJSON, monitoringStaleTaskDropReason)
	if err != nil {
		return response.ErrInternal(50192, "desktop_task_stale_query_failed", "failed to select stale monitor desktop tasks")
	}
	defer rows.Close()

	repo := repository.NewDesktopTaskRepository(tx)
	droppedTaskIDs := make([]uuid.UUID, 0)
	for rows.Next() {
		var (
			taskID    uuid.UUID
			attemptID pgtype.UUID
		)
		if scanErr := rows.Scan(&taskID, &attemptID); scanErr != nil {
			return response.ErrInternal(50193, "desktop_task_stale_scan_failed", "failed to parse stale monitor desktop tasks")
		}

		droppedTaskIDs = append(droppedTaskIDs, taskID)

		if !attemptID.Valid {
			continue
		}

		resolvedAttemptID, convErr := uuid.FromBytes(attemptID.Bytes[:])
		if convErr != nil {
			s.logWarn("desktop stale monitor attempt id decode failed", convErr, zap.String("task_id", taskID.String()))
			continue
		}

		if finishErr := repo.FinishAttempt(ctx, repository.FinishDesktopTaskAttemptParams{
			TaskID:      taskID,
			AttemptID:   resolvedAttemptID,
			FinalStatus: literalStringPtr("aborted"),
			Error:       errorJSON,
		}); finishErr != nil {
			s.logWarn("desktop stale monitor attempt finish failed", finishErr, zap.String("task_id", taskID.String()))
		}
	}
	if err := rows.Err(); err != nil {
		return response.ErrInternal(50193, "desktop_task_stale_scan_failed", "failed to iterate stale monitor desktop tasks")
	}

	if err := tx.Commit(ctx); err != nil {
		return response.ErrInternal(50194, "desktop_task_stale_commit_failed", "failed to commit stale monitor desktop cleanup")
	}

	for _, taskID := range droppedTaskIDs {
		task, getErr := s.repo.GetByDesktopID(ctx, taskID, client.WorkspaceID)
		if getErr != nil {
			s.logWarn("desktop stale monitor reload failed", getErr, zap.String("task_id", taskID.String()))
			continue
		}
		s.publishTaskEvent(ctx, task, "task_canceled")
	}

	if _, err := s.monitoringPool.Exec(ctx, `
		UPDATE monitoring_collect_tasks
		SET status = 'skipped',
		    lease_token_hash = NULL,
		    leased_to_executor = NULL,
		    leased_at = NULL,
		    lease_expires_at = NULL,
		    callback_received_at = COALESCE(callback_received_at, NOW()),
		    completed_at = COALESCE(completed_at, NOW()),
		    skip_reason = $4,
		    error_message = COALESCE(NULLIF(error_message, ''), $5),
		    updated_at = NOW()
		WHERE tenant_id = $1
		  AND collector_type = $2
		  AND COALESCE(execution_owner, 'legacy') = 'desktop_tasks'
		  AND target_client_id = $3
		  AND business_date < $6::date
		  AND callback_received_at IS NULL
		  AND status IN ('pending', 'leased', 'expired')
	`, client.TenantID, monitoringCollectorType, client.ID, monitoringStaleTaskDropReason, monitoringStaleTaskDropError, currentBusinessDate); err != nil {
		return response.ErrInternal(50041, "task_skip_failed", "failed to drop stale phase2 monitoring tasks")
	}

	return nil
}

func activeAttemptID(task *repository.DesktopTask) *uuid.UUID {
	if task == nil || task.ActiveAttemptID == nil {
		return nil
	}
	value := *task.ActiveAttemptID
	return &value
}

func shouldRequeuePreemptedMonitorTask(task *repository.DesktopTask, reason *string) bool {
	if task == nil || task.Kind != "monitor" {
		return false
	}
	return strings.EqualFold(strings.TrimSpace(optionalStringValue(reason)), "collect_now_preempt")
}

func requeuePreemptedMonitorTask(
	ctx context.Context,
	tx pgx.Tx,
	repo repository.DesktopTaskRepository,
	task *repository.DesktopTask,
) (*repository.DesktopTask, error) {
	if task == nil {
		return nil, nil
	}
	replacementID := uuid.New()
	replacementJobID := uuid.New()
	if _, err := tx.Exec(ctx, `
		INSERT INTO desktop_tasks (
			desktop_id,
			job_id,
			tenant_id,
			workspace_id,
			target_account_id,
			target_client_id,
			platform_id,
			kind,
			payload,
			status,
			priority,
			lane,
			lane_weight,
			source,
			scheduler_group_key,
			monitor_task_id,
			supersedes_task_id,
			control_flags,
			interrupt_generation,
			enqueued_at
		)
		VALUES (
			$1,
			$2,
			$3,
			$4,
			$5,
			$6,
			$7,
			'monitor',
			$8,
			'queued',
			50,
			'retry',
			20,
			'retry_recovery',
			$9,
			$10,
			$11,
			jsonb_build_object(
				'interrupt_requested', false,
				'requeued_at', NOW()::text,
				'requeued_from_task_id', $11::text,
				'requeued_reason', 'collect_now_preempt'
			),
			$12,
			NOW()
		)
	`, replacementID, replacementJobID, task.TenantID, task.WorkspaceID, task.TargetAccountID, task.TargetClientID, task.Platform, task.Payload, nullableString(task.SchedulerGroupKey), nullableInt64(task.MonitorTaskID), task.DesktopID, task.InterruptGeneration); err != nil {
		return nil, response.ErrInternal(50111, "desktop_task_requeue_failed", "failed to create replacement retry monitor desktop task")
	}

	next, err := repo.GetByDesktopID(ctx, replacementID, task.WorkspaceID)
	if err != nil {
		return nil, response.ErrInternal(50112, "desktop_task_lookup_failed", "failed to reload replacement retry monitor desktop task")
	}
	return next, nil
}

func (s *DesktopTaskService) publishTaskEvent(ctx context.Context, task *repository.DesktopTask, eventType string) {
	if task == nil {
		return
	}

	title, businessDate, schedulerGroupKey, questionText := deriveDesktopTaskEventMetadataFromPayload(task.Kind, task.Payload)
	event := DesktopTaskEvent{
		Type:                eventType,
		TaskID:              task.DesktopID.String(),
		JobID:               task.JobID.String(),
		WorkspaceID:         task.WorkspaceID,
		TargetAccountID:     task.TargetAccountID.String(),
		TargetClientID:      task.TargetClientID.String(),
		Platform:            task.Platform,
		Title:               title,
		BusinessDate:        businessDate,
		SchedulerGroupKey:   schedulerGroupKey,
		QuestionText:        questionText,
		Status:              task.Status,
		Kind:                task.Kind,
		Priority:            task.Priority,
		Lane:                task.Lane,
		InterruptGeneration: task.InterruptGeneration,
		UpdatedAt:           task.UpdatedAt,
	}
	err := publishDesktopTaskEvent(ctx, s.messaging, event)
	if err != nil {
		s.logWarn("desktop task event publish failed", err, zap.String("task_id", task.DesktopID.String()), zap.String("event_type", eventType))
	}

	if dispatchErr := publishDesktopDispatchEvent(ctx, s.messaging, s.logger, stream.DesktopDispatchEvent{
		Type:                event.Type,
		TaskID:              event.TaskID,
		JobID:               event.JobID,
		WorkspaceID:         event.WorkspaceID,
		TargetAccountID:     event.TargetAccountID,
		TargetClientID:      event.TargetClientID,
		Platform:            event.Platform,
		Title:               event.Title,
		BusinessDate:        event.BusinessDate,
		SchedulerGroupKey:   event.SchedulerGroupKey,
		QuestionText:        event.QuestionText,
		Status:              event.Status,
		Kind:                event.Kind,
		Priority:            event.Priority,
		Lane:                event.Lane,
		InterruptGeneration: event.InterruptGeneration,
		UpdatedAt:           event.UpdatedAt,
	}); dispatchErr != nil {
		s.logWarn("desktop dispatch mirror publish failed", dispatchErr, zap.String("task_id", task.DesktopID.String()), zap.String("event_type", eventType))
	}
}

func (s *DesktopTaskService) logWarn(message string, err error, fields ...zap.Field) {
	if s.logger == nil || err == nil {
		return
	}
	fields = append(fields, zap.Error(err))
	s.logger.Warn(message, fields...)
}