feat(campaign-packer): paginate audience and publish campaigns.send (EVO-1216)

[nickoliveira23]

Summary

Implements story 4.2 (Campaign Dispatch Pipeline): extends CampaignPackerService.pack() (from 4.1 / EVO-1215) to paginate the resolved audience and publish one campaigns.send message per page, enabling the horizontal fan-out of the campaign-sender (4.3).

• New PaginationService: pure, O(n) split(contactIds, batchSize) into 1-based pages (page ≤ totalPages).
• pack() now: loads the campaign (with templates), computes audience, loads the persisted (PENDING) contactIds, then:
  • empty audience → publishes one campaigns.tracked with {page:0, sentCount:0, failedCount:0, completed:true} + logs campaign has no contacts (so CampaignWorkflow closes instead of hanging);
  • non-empty → resolves templateId (A-variant) + channelType, splits, and publishes one campaigns.send per page.
• channelType mapping: CRM stores the Rails STI name (Channel::Email); the broker contract uses the transport id (email). Bridged at the publish boundary.
• CAMPAIGN_PACKER_BATCH_SIZE env (default 1000), clamped against 0/NaN.
• CampaignNotConfiguredError extends TerminalError for a campaign missing channel type or message template (drops, no requeue loop).
• correlationId propagated from the incoming campaigns.pack payload to every published message.

Security

• Internal broker consumer (no auth surface, single-account).
• Misconfigured campaign (no channel/template) → TerminalError → terminal drop, never a redelivery loop.

Test plan

• evo-flow: npm run typecheck — clean
• evo-flow: npx jest src/runners/campaign-packer/services/pagination.service.spec.ts src/runners/campaign-packer/services/campaign-packer.service.spec.ts — 15 examples, 0 failures
• evo-flow: npx eslint <changed .ts> — production files clean (specs follow the existing campaign-packer spec baseline)

Covers ACs: split math at 2500→[1000,1000,500] / exact-multiple (AC1/AC3), 1500→2 pages (AC3), empty→tracked+warn (AC2), payload validated against the strict campaigns.send zod contract + channelType mapping (AC4).

Notes

• At-least-once semantics: a publish failure mid-loop nacks → redelivery re-publishes all pages; combined with clearAudience on re-pack this opens a double-send window. By design the campaign-sender (4.3) dedups via CampaignContact.status; broker-level redelivery backstop is tracked in EVO-1677. Out of scope here.
• Audience materialization: loadContactIds reads the full PENDING audience via find({ select: { contactId } }); at ~1M contacts a getRawMany projection would avoid entity hydration — optional perf follow-up, in-memory split is the approach the card prescribes.
• Pagination metrics are intentionally out of scope (story 5.2); a campaign.paginated structured log was added for observability.

Changed Files

• src/runners/campaign-packer/services/pagination.service.ts (new)
• src/runners/campaign-packer/services/pagination.service.spec.ts (new)
• src/runners/campaign-packer/services/campaign-packer.service.ts
• src/runners/campaign-packer/services/campaign-packer.service.spec.ts
• src/runners/campaign-packer/errors/campaign-not-configured.error.ts (new)
• src/runners/campaign-packer/campaign-packer.module.ts

Linked Issue

• EVO-1216

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