---
status: open
opened: 2026-09-30
located-in:
  - mesh-catalog (no module shares a path over the network)
  - hq 02-DECISIONS (a file-share seat, per ADR 0126, is a module's own to define)
fixed-by:
amended-design:
---

# 169 — A machine shares its files, and the mesh does not know

## What was observed

ace serves the operator's media library to the home network with two host services no module
declares and HAL never managed either:

```
/etc/exports:   /storage/media  192.168.1.0/24(rw,sync,root_squash,…)     nfs-server active, :2049
/etc/samba/smb.conf: [media] path = /storage/media/  valid users = media   smb active, :139/:445
```

Two LAN clients were connected at survey (2026-09-30). The library itself is operator data
(ADR 0051: ~40 TB on ZFS, the mesh owns nothing about it — [issue 153](../153-an-adopted-machines-data-cannot-be-placed-where-it-is/00-report.md)
is about modules reaching it in place).

Under the mesh as it stands, this arrangement has no expression and one failure mode:

- **Nothing declares the listens.** At `converge ace` the filter is the sum of what modules listen
  on (ADR 0045); 2049 and 445 are nobody's, so the shares close — silently, for the two clients
  that mount them.
- **Nothing owns the configuration.** `/etc/exports` and `smb.conf` are hand-written files on one
  machine; a second machine sharing a directory would be written by hand again.
- **Nothing can consume it.** A module on another node that wanted the library (a player, an
  indexer, a backup) has no `requires` to state and no binding to read; it would mount by a
  hand-typed host and path.
- The clients are LAN devices, so this also meets [issue 154](../154-a-machines-own-network-is-not-a-reach/00-report.md)
  (no reach for the machine's own network).

## The proposal (the operator's, 2026-09-30, settled after two rounds)

**Two module-defined seats, one per protocol, because NFS and SMB share an intent and not a
contract.** A seat in the mesh's sense is a contract — what it accepts, emits and serves, and the
tools its holder must answer (ADR 0126, 0132) — and lined up, the two share almost none of it:

| | `nfs-share` | `smb-share` |
|---|---|---|
| serves | export path(s); the client ranges allowed (`sec=sys` authorises by address) | share name(s), path |
| pair credential | none | a user and password per consumer |
| consumer's mount | `at:/path` | `//at/share` with credentials |
| holder's tools | export / unexport a path for a range | add / remove a share, create a user |

One `file-share` seat would be the union with every field optional — a consumer could bind it and
still not know how to mount what it got (the emptiness ADR 0129 warns against). "Export a path to
the network" is a category, and the mesh needs no seat category: a consumer requires the one it
can mount. If "give me the library, however" is ever needed, it is a provision an umbrella module
serves, not a seat.

Both are node-scoped, one holder per node (ADR 0110), so ace holds both. `nfs` and `samba` are the
first implementations; a second (Ganesha for `nfs-share`, ksmbd for `smb-share`) is what proves
0126's promise that "replacing the implementation changes nothing for any caller".

The holder module:

- declares the exported paths as `accesses` (ADR 0051: it owns nothing about them — never creates,
  chowns or removes), and *which* paths as the assignment's settings (ADR 0046/0112);
- writes the share configuration (`/etc/exports`, `smb.conf`) as mesh-managed files and drives the
  units, like `dnsmasq`/`sshd` do for theirs;
- declares its endpoints (`nfs` 2049/tcp; `smb` 445/tcp, …) so the reach — internal, or the LAN
  once 154 has an answer — is the assignment's, and converge keeps them open;
- **provides** the seat's provision, so a consumer on another node `requires nfs-share` (or
  `smb-share`) and reads `${bound:nfs-share:at}` and the path from its binding instead of a
  hand-typed mount.

## The design gap this exposes

**A seat definition has no home outside the module that first declared it.** Today a seat is
declared inside a manifest (`showcase` declares `the-showcase`, `ca-trust` its own). If `nfs`
declared `nfs-share`, Ganesha could hold it only by depending on nfs's manifest — the coupling
0126 removed for callers, reintroduced for implementations. The protocol needs a neutral place in
the catalogue beside the modules (a seat definition registered like a manifest), with a module
saying which seats it implements. This is the first role with an obvious second implementation,
which is what makes it the exemplar for that mechanism.

## Open questions for the decision

- Whether an NFS export over the overlay is an `internal` reach of the same endpoint or a second
  export line — NFS authorises by client address, so the mesh range and the LAN range are two
  entries in one file.
- How a consumer's binding expresses a *path* to mount (today bindings carry `at`, `port`, `as` and
  whatever the provider `serves`), and whether one share can serve several paths.