Status: ready-for-human

# 17 — DOC: Duplicate US-020 issue dedup

## What to build

Two files share the US-020 number with different slugs:

- `docs/issues/20-memory-budget-shard-slots-and-dropout-relocation.md` (ready-for-agent)
- `docs/issues/20-tracker-node-hardening.md` (done)

Resolve numbering collision without losing history.

## Acceptance criteria

- [ ] Document canonical mapping in this issue's Comments or a short `docs/issues/README.md` note
- [ ] Renumber or prefix disambiguation (e.g. keep done item as US-020a, renumber memory-budget to next slot) — **human approval before git mv**
- [ ] Update any prd.json / cross-links that reference US-020 ambiguously
- [ ] No production code changes

## Blocked by

Human approval for renumbering. An agent may prepare the mapping note, but must not run `git mv` or rewrite cross-links until the canonical number is approved.