hq/03-DESIGN/01-to-be/14-model-access.md

layer, status, code, updated, decisions

layer	status	code	updated	decisions
to-be	in-progress	mesh-controller internal/licences mesh-controller cmd/mesh-controller/licence.go	2026-09-05	02-DECISIONS/0024-model-access-is-a-provision.md 02-DECISIONS/0009-modules-and-the-graph.md

14 — Model access

ADR 0024 decided it and listed four things the mesh did not have. Written 2026-08-31, when two of them were built. The other two are still gaps and are still written as gaps — the record's own warning is that pretending otherwise is how a plan becomes a surprise.

What was built

A licence is a record, and the first provision no machine answers. Everything else the mesh brokers is answered by something running on a node. A hosted model is on nobody's machine and is reached over the public internet, so the rule that refuses two ends sharing no private network — correct everywhere else — must not apply to it. A machine on no private network at all can hold a licence, and that is not a special case to remember: it falls out of the answer not being a machine.

The name is the operator's. The personal account, the organisation's account. Those are names a person uses, and the mesh uses them too, because the whole point is saying which one a consumer uses — and an anonymous credential hanging off a provider cannot be said. Many to many, so deliberately not a claim: two machines sharing an account is the ordinary case rather than a collision.

One provision name for all of them. A module requires model-access, never anthropic. A module that named a provider could not be moved onto a model the mesh runs itself without editing it — and moving it is the point.

A model in a machine's own set answers it locally, and no record is consulted. That is what makes the mesh's own model an ordinary answer rather than a parallel arrangement.

Accept: taking a value the mesh did not make

Every other credential here the mesh generated, sealed to both ends and discarded. An API key arrives from a person, and the missing verb was accept: take a value, seal it to each holder, discard the plaintext. A mesh that kept operator-supplied keys readably is the arrangement this project measured and rejected.

It seals to the holders that exist at that moment, and this has a consequence that must be said out loud rather than discovered:

A consumer put on a licence after the key was supplied has no key, and the mesh cannot make one — it discarded the only copy.

So that state is reported at every point a person could meet it: when the consumer is put on the licence, in licence list, and — decisively — the declaration is refused rather than written without the file. A machine that resolves cleanly and receives nothing fails later, somewhere that names neither the licence nor the mesh.

A key is read from a file or standard input, never an argument. A key on a command line is a key in shell history and in every process listing taken while it ran. It is never echoed back: what is stored is unreadable by whoever holds it, the controller included, and printing it would put the one copy that matters on a terminal.

Refusing is felt, and that is the design working

ADR 0024 predicted it: a mesh holding three ways to reach a model refuses every consumer that has not said which — which is correct and is a great deal of saying-which the first time.

It is correct, and correct is not the same as usable. So the refusal names the candidates and the exact command. The difference between a mesh that refuses helpfully and one that merely refuses is whether anybody can act on it without going and reading something else.

Still gaps

Unchanged from ADR 0024, and deliberately not half-built:

A consumer that is not a machine. This worker uses that licence is a binding to an agent, not to a node. What is delivered still lands on a machine; what is chosen is chosen per agent, and the provisions model has no consumer identity other than a node. What exists today is per module per machine, which is a step toward it and is not it.

2026-08-31: this gap now has named consumers rather than hypothetical ones. ADR 0026 puts two sessions on the controller node — the node's own and the mesh's — each bound in its own right. See 15-the-agent-session.md.

And for sessions the gap is already closed, which was not obvious. A binding is per module per machine, and this document called that a step toward it and not it — reasoning that a machine cannot name an agent. It cannot; but the two sessions are two modules, because they are the same mechanism started in different context roots and a context root is what a module delivers. So (node, module) tells them apart, and asking for a licence per session needed no new consumer identity. Checked rather than argued: two sessions on one machine hold different licences, each is given its own key, and releasing one leaves the other.

What is still open is the rest of the gap, and it is the harder half. A worker is not one per machine — many can run on one, from one module — so (node, module) cannot name them apart and this reasoning does not extend to them. That belongs with ADR 0003, which is unbuilt, and it is the reason this section stays open rather than being struck out.

Switching is a reaction, not a declaration. A licence that hits its limit and must be swapped is a response to something observed. Expressing it as a declaration would make the declaration mean whatever is working right now, which is not a thing anybody declared. It belongs with observability, changing a binding — and the binding is then declared as usual. Saying this plainly is what stops the declaration language growing a conditional, and nothing built here grew one.

The vendor-agnostic generalisation

ADR 0050 is accepted; this section describes what it decides. The section above stands as what is built today.

What runs is one vendor — the mesh's Anthropic feature. A read-only trace asked whether the model-access provision is Anthropic-shaped or genuinely general, and found that the general layer already exists: a licence is a record with a vendor and a non-secret serves, a holder's credential is sealed per holder, accept takes an operator-supplied value and discards the plaintext, and a locally-run model answers at node scope with no licence. None of that names Anthropic. What is Anthropic's is a thin band: the credential is a subscription OAuth grant — an hourly access token and a refresh token — and that shape alone drags central rotation, a refresh-token-stripping delivery, an identity guard and a utilization% usage reading behind it.

A vendor is an adapter. The vendor-specific lifecycle moves into a per-vendor adapter selected by the licence's vendor field — the same shape as a registrar-scoped public-dns provider behind the neutral public-dns interface (ADR 0044). A consumer still requires model-access and never names a vendor; the interface is drawn at the consumer's real coupling — reach a model — per ADR 0040. The field is vendor rather than provider, because "provider" already means which node answers a brokered provision and the two facts must not share a word.

The adapter declares a shape — static-key or refreshable-grant — and, optionally, the verbs a vendor happens to need: accept a supplied key, refresh a grant, read an identity off the credential to catch a mis-binding, report usage, and deliver the value. A static-key vendor implements almost nothing — a supplied key, sealed to its holders, delivered. The abstraction is built so the common vendor is small and the rare one carries its own weight.

                requires: model-access          (the consumer, vendor-blind)
                          │
                   ┌──────┴───────┐
                   │  a licence   │  vendor: …   serves: base URL, model
                   └──────┬───────┘
              selected by │ vendor
        ┌─────────────────┼──────────────────────────┐
        ▼                 ▼                            ▼
  anthropic-api-key   anthropic                    (another vendor)
  shape: static-key   shape: refreshable-grant
  accept, deliver     accept, refresh, identity,
                      usage, deliver

The crux is one relaxation, stated plainly. A refreshable credential cannot be both sealed so the mesh cannot read it and rotated centrally — rotation needs a readable refresh token, and the working central rotation is the half ADR 0024 keeps on purpose. So for refreshable-grant vendors only, the manager node holds the refresh token encrypted at rest — a bounded, declared exception. Access tokens stay sealed per holder, and the refresh token is stripped on delivery, so a node never holds a refresh token remains true for every node but the one manager. Static-key vendors keep the full guarantee: there is nothing to rotate, so accept discards the plaintext and the carve-out never fires — and static-key is the majority. The exception is written down because a relaxed guarantee that is not stated is indistinguishable from a broken one, and it is narrow on three axes at once: refreshable-grant only, the refresh token only, the manager node only.

Usage is normalised to (licence, consumer, period, metric, value) with the raw response kept beside it; the metric is vendor-defined, so no false common unit is forced. Anthropic becomes the first refreshable-grant adapter, and anthropic-api-key — the same vendor's plain keys — is the static-key case that proves the abstraction is more than one vendor in disguise.

How it is checked

In the lab, on real machines, in the order a person would meet it: a consumer is refused with both candidates named; put on one and still refused because no key exists; the key is given on standard input and not echoed; the public half arrives saying it came from a record rather than a machine; the key arrives readable only by that machine — and it is nowhere in the controller's own database, nor in anything that crossed the broker.

For the generalisation (ADR 0050): a second vendor — anthropic-api-key, static-key — is bound to a consumer and exercises the whole path with the carve-out switched off, its key sealed per node and absent from the controller's database. For a refreshable-grant licence, the refresh token is asserted to exist (encrypted) only on the manager node, to be absent from every holder's delivery, and the delivered credential to be access-token-only; a static-key licence stores no refresh token anywhere. A scenario with two vendors confirms each licence's lifecycle runs its own adapter, selected by vendor.