Add worker that regenerates the tracker policy

Add a poll-based tracker policy worker that claims banners flagged for
policy generation, clears the flag, and rebuilds the cookie and
tracking technologies policy from the latest published snapshot. A
banner that lost its published version is skipped rather than failed.

Wire the worker into probod with crash propagation and graceful
shutdown alongside the other tracker workers.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/probo/tracker_policy_document.go

@@ -72,13 +72,8 @@ func (s *GeneratedDocumentService) PublishTrackerPolicy(
 	ctx context.Context,
 	scope coredata.Scoper,
 	cookieBannerID gid.GID,
-) (*coredata.Document, *coredata.DocumentVersion, error) {
-	var (
-		document        *coredata.Document
-		documentVersion *coredata.DocumentVersion
-	)
-
-	err := s.svc.pg.WithTx(
+) error {
+	return s.svc.pg.WithTx(
 		ctx,
 		func(ctx context.Context, tx pg.Tx) error {
 			banner := &coredata.CookieBanner{}
@@ -103,7 +98,10 @@ func (s *GeneratedDocumentService) PublishTrackerPolicy(
 
 			now := time.Now()
 
-			var existingDoc *coredata.Document
+			var (
+				document    *coredata.Document
+				existingDoc *coredata.Document
+			)
 
 			if banner.PolicyDocumentID != nil {
 				doc := &coredata.Document{}
@@ -153,7 +151,7 @@ func (s *GeneratedDocumentService) PublishTrackerPolicy(
 			}
 
 			documentVersionID := gid.New(scope.GetTenantID(), coredata.DocumentVersionEntityType)
-			documentVersion = &coredata.DocumentVersion{
+			documentVersion := &coredata.DocumentVersion{
 				ID:             documentVersionID,
 				OrganizationID: banner.OrganizationID,
 				DocumentID:     document.ID,
@@ -169,11 +167,6 @@ func (s *GeneratedDocumentService) PublishTrackerPolicy(
 			return s.publishOrRequestApproval(ctx, scope, tx, document, documentVersion, banner.OrganizationID, nil, false, now)
 		},
 	)
-	if err != nil {
-		return nil, nil, err
-	}
-
-	return document, documentVersion, nil
 }
 
 func (s *GeneratedDocumentService) buildTrackerPolicyDocumentData(

pkg/probo/tracker_policy_worker.go

@@ -0,0 +1,109 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package probo
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"go.gearno.de/kit/log"
+	"go.gearno.de/kit/pg"
+	"go.gearno.de/kit/worker"
+	"go.probo.inc/probo/pkg/coredata"
+)
+
+type trackerPolicyHandler struct {
+	generatedDocuments *GeneratedDocumentService
+	pg                 *pg.Client
+	logger             *log.Logger
+}
+
+// NewTrackerPolicyWorker returns a worker that regenerates a banner's cookie
+// and tracking technologies policy document whenever a banner version is
+// published. Publishing sets policy_generation_requested_at on the banner; this
+// worker claims those banners, clears the flag, and rebuilds the policy from
+// the latest published snapshot.
+func NewTrackerPolicyWorker(
+	generatedDocuments *GeneratedDocumentService,
+	pgClient *pg.Client,
+	logger *log.Logger,
+	opts ...worker.Option,
+) *worker.Worker[coredata.CookieBanner] {
+	h := &trackerPolicyHandler{
+		generatedDocuments: generatedDocuments,
+		pg:                 pgClient,
+		logger:             logger,
+	}
+
+	return worker.New(
+		"tracker-policy-worker",
+		h,
+		logger,
+		opts...,
+	)
+}
+
+func (h *trackerPolicyHandler) Claim(ctx context.Context) (coredata.CookieBanner, error) {
+	var banner coredata.CookieBanner
+
+	if err := h.pg.WithTx(
+		ctx,
+		func(ctx context.Context, tx pg.Tx) error {
+			if err := banner.LoadNextForPolicyGenerationForUpdateSkipLocked(ctx, tx); err != nil {
+				return err
+			}
+
+			return banner.ClearPolicyGenerationRequestedAt(ctx, tx)
+		},
+	); err != nil {
+		if errors.Is(err, coredata.ErrResourceNotFound) {
+			return coredata.CookieBanner{}, worker.ErrNoTask
+		}
+
+		return coredata.CookieBanner{}, fmt.Errorf("cannot claim tracker policy task: %w", err)
+	}
+
+	return banner, nil
+}
+
+func (h *trackerPolicyHandler) Process(ctx context.Context, banner coredata.CookieBanner) error {
+	scope := coredata.NewScopeFromObjectID(banner.ID)
+
+	if err := h.generatedDocuments.PublishTrackerPolicy(ctx, scope, banner.ID); err != nil {
+		// A banner can lose its published version between the publish that
+		// armed the flag and this run (e.g. it was deleted). There is nothing
+		// to generate in that case, so skip rather than fail the task.
+		if errors.Is(err, coredata.ErrResourceNotFound) {
+			h.logger.InfoCtx(
+				ctx,
+				"skipping tracker policy generation: no published version",
+				log.String("banner_id", banner.ID.String()),
+			)
+
+			return nil
+		}
+
+		return fmt.Errorf("cannot generate tracker policy: %w", err)
+	}
+
+	h.logger.InfoCtx(
+		ctx,
+		"generated tracker policy document",
+		log.String("banner_id", banner.ID.String()),
+	)
+
+	return nil
+}

pkg/probod/probod.go

@@ -732,6 +732,17 @@ func (impl *Implm) Run(
 		},
 	)
 
+	trackerPolicyWorker := probo.NewTrackerPolicyWorker(proboService.GeneratedDocuments, pgClient, l)
+	trackerPolicyWorkerCtx, stopTrackerPolicyWorker := context.WithCancel(context.Background())
+
+	wg.Go(
+		func() {
+			if err := trackerPolicyWorker.Run(trackerPolicyWorkerCtx); err != nil {
+				cancel(fmt.Errorf("tracker policy worker crashed: %w", err))
+			}
+		},
+	)
+
 	trackerMappingWorker := cookiebanner.NewTrackerMappingWorker(
 		pgClient,
 		l,
@@ -870,6 +881,7 @@ func (impl *Implm) Run(
 	stopWebhookSender()
 	stopESignService()
 	stopTrackerPatternAnalysisWorker()
+	stopTrackerPolicyWorker()
 	stopTrackerMappingWorker()
 	stopCommonPatternEnrichmentWorker()
 	stopMailingListWorker()