Coreex Subscriber E2e

---
name: coreex-subscriber-e2e
description: "Create a complete new event or command subscriber end-to-end in a single guided workflow: event/command DTO contract (if new), subscriber handler, optional application service and repository, and integration tests. USE FOR: adding a brand-new subscriber to an existing CoreEx Subscribe host for any scenario — command handling, event-data-sync replication, or event-driven business-process choreography. DO NOT USE FOR: modifying an existing subscriber (use coreex-subscriber directly), API endpoint work (use coreex-api-e2e), or setting up the Subscribe host itself (use coreex-solution-scaffolder)."
argument-hint: "Optional: event or command subject, subscriber scenario (command / event-data-sync / business-process)"
tags: ["coreex", "subscriber", "event", "command", "end-to-end", "vertical-slice", "messaging"]
---

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# CoreEx: Add Subscriber (End-to-End)

Guides you through adding a complete new event or command subscriber in one sitting: gathers all context upfront, identifies the right scenario path, then invokes the appropriate L1 skills in sequence so you are never asked the same question twice.

## When to Use

- Adding a brand-new subscriber to an existing CoreEx Subscribe host
- You know the event or command subject and want the full slice — contract, handler, optional orchestration, and tests — in one workflow
- Covers all three subscriber scenarios: command handling, event-data-sync replication, and event-driven business-process choreography

## When Not to Use

- Modifying an existing subscriber handler — invoke `coreex-subscriber` directly
- Setting up the Subscribe host itself (it does not yet exist) — use `coreex-solution-scaffolder`
- Building an API endpoint — use `coreex-api-e2e`

## Workflow Overview

1. **Read Feature Configuration** — resolve `messaging-provider`, `outbox-enabled`, `data-provider`, and `rop-enabled` from the solution-root `AGENTS.md` before asking anything.
2. **Interview** — identify the subject, scenario, DTO needs, and whether state persistence is required; batch all questions into one turn.
3. **Execute L1 sequence** — invoke each applicable L1 skill in order, passing context resolved in steps 1–2; no repeated questions.
4. **Validate** — `dotnet build`; confirm the subscriber is registered and integration tests are present.

For full step-by-step guidance see [`references/workflow.md`](references/workflow.md).

## L1 Sequence

| Step | Skill | Condition |
|---|---|---|
| 1 | [`coreex-contract`](../coreex-contract/SKILL.md) | Only if a new event/command DTO type is needed |
| 2 | [`coreex-db-migration`](../coreex-db-migration/SKILL.md) | Only for business-process scenario when a new local entity table is needed (`data-provider ≠ None`) |
| 3 | [`coreex-repository`](../coreex-repository/SKILL.md) | Only when Step 2 runs |
| 4 | [`coreex-app-service`](../coreex-app-service/SKILL.md) | Only for command and business-process scenarios that need orchestration beyond a direct adapter/sync call |
| 5 | [`coreex-subscriber`](../coreex-subscriber/SKILL.md) | Always |
| 6 | [`coreex-test-subscribe`](../coreex-test-subscribe/SKILL.md) | Always |

## Scenario Paths at a Glance

| Scenario | Steps that run |
|---|---|
| **Command handler** — inbound command triggers an app-service action | 1 (if new DTO) → 4 → 5 → 6 |
| **Event-data-sync** — inbound event replicates data into a local store via `IXxxSyncAdapter` | 1 (if new DTO) → 5 → 6 |
| **Business-process choreography** — inbound event triggers a multi-step business process | 1 (if new DTO) → 2 + 3 (if new entity) → 4 → 5 → 6 |

## Key References

- [`/.github/instructions/coreex-event-subscribers.instructions.md`](/.github/instructions/coreex-event-subscribers.instructions.md) — subscriber conventions, ValueValidator, ErrorHandler, subject naming
- [`/.github/instructions/coreex-application-services.instructions.md`](/.github/instructions/coreex-application-services.instructions.md) — app-service orchestration and Result&lt;T&gt; pipeline
- [`/.github/instructions/coreex-tests.instructions.md`](/.github/instructions/coreex-tests.instructions.md) — subscriber integration test conventions
- [`/.github/instructions/coreex-host-setup.instructions.md`](/.github/instructions/coreex-host-setup.instructions.md) — Subscribe host DI registration