---
id: CANP-WP-0005
type: workplan
title: "Document and detect inclusion diamonds"
domain: agents
repo: canned-prompts
status: proposed
owner: codex
topic_slug: practice
created: "2026-09-06"
updated: "2026-09-06"
state_hub_workstream_id: "773f08a3-f899-53fc-87c8-037f8ffbd24d"
---

# Document and detect inclusion diamonds

Residual from `CANP-WP-0004` (`origin: residual`, `origin_ref: CANP-WP-0004`).

## Warn about repeated inclusion

```task
id: CANP-WP-0005-T01
status: todo
priority: medium
state_hub_task_id: "74234a7a-c3bd-5bf7-a40d-21ddf208cfb5"
```

CPF inclusion (§ 10.4) does not deduplicate: when one package reaches the same
dependency by two paths, the included text renders once per path. This was found
by building a real collection — `helix/repo-advance` rendered its conventions
block twice — and worked around downstream by factoring the shared routine into
its own fragment.

§ 10.4 says nothing about it, so an author meets the behaviour only by reading
the output carefully. That silence is the defect.

Two questions, and the second depends on the first:

1. **Document it.** State in § 10.4 that inclusion is textual and repeated,
   not deduplicated, and give the factoring pattern that avoids a diamond.
2. **Detect it.** Decide whether validation should warn when a package reaches
   the same dependency by more than one path. A warning is cheap and catches the
   mistake at `add` time. Silently deduplicating is a different proposition
   entirely — it would mean choosing which occurrence survives, and deciding what
   happens when two paths resolve *different versions* of the same dependency.
   That is resolver behaviour, and § 10.4 keeps composition declarative on
   purpose.

Leaning: document it now, warn at validation time, and do not deduplicate.