---
id: architecture/n5-unborn-head-rider
name: Verify ls-refs=unborn serving (unborn-HEAD fixture, both substrates)
status: pending
depends_on: []
scope: narrow
risk: low
impact: wire-claim
level: implementation
tags: [verification-rider, advertisement-honesty]
---

## Description

Review 001 N-5: `ls-refs=unborn` is advertised (transport.md §advertisement,
ADR-003), and POC-1 validated real git accepting the capability *token* —
but serving an unborn HEAD's symref line was never exercised against a
real client (every POC fixture had refs). This is the only advertised
promise in the corpus without capture evidence. The rider is the
verification that closes it.

## Work

Implementation-phase test (lands with the ls-refs workstream):

1. Fixture: an unborn repo — registry record exists, `git init`-equivalent
   storage with no refs (the POC set's unborn repo has refs; a new one
   without any is needed).
2. V2 ls-refs against it over the duplex substrate with a real git client
   (`git -c protocol.version=2 ls-remote`), asserting the unborn HEAD
   symref line appears per the ls-refs grammar
   (`<zero-oid> HEAD symref-target:refs/heads/<default>` unpeeled).
3. Same over the stateless (smart-http-shape) substrate.
4. Backend seam: the refs listing must expose the unborn symref for an
   empty repo — verify the `GitRefs` trait shape carries it (a
   `symref-target` with no oid); adjust the trait surface if the gix
   listing cannot produce it.

If it cannot be served correctly: drop the `ls-refs=unborn` token from
the advertisement (the honest move per ADR-003 — decline by omission)
and record the drop in transport.md §advertisement.

## Verification

- Real `git ls-remote` (V2) against an unborn repo lists the unborn HEAD
  symref line, both substrates.
- The full advertisement suite still passes against repos with refs
  (the token must not change the served behavior there).

## Out of scope

- Unborn-HEAD push (an unborn repo's first push is ordinary ref creation
  — ADR-013; not this rider).
- Any capability beyond the token's existing grammar.

## Summary

> Filled on completion.