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jochen 4a1b218706 Seats held by assignments, one assignment per module per node, and 0113's bottom of the stack 
Decided with the author:
- A seat is held by one assignment, not claimed by a definition. A definition says which seats a module
  can hold; an assignment says which it does. The store module can run on every node and one assignment
  holds mesh-store; moving a role changes an assignment, never a definition. The foundation's seats name
  what the mesh itself uses and route no consumer — database and amqp consumers use co-location, the
  holder included. This replaces the wrong rationale that the foundation's store is "provider to nobody",
  which contradicted ADR 0078 and to-be 21. 0079's one-postgres rule becomes one mesh-store holder.
- A module is assigned at most once to a node. The instance identity in 0112 and 27 is withdrawn, and the
  login-length problem with it.

Review fixes to 0113:
- The bottom of the stack: the vault is installed as soon as the shared runtime base exists, and genesis
  generates everything needed until then — including the permanent controller's, the control-node
  agent's, the builder's and the broker provisioner's bus accounts, and the controller's store login.
  Genesis creates those accounts until the broker's provisioner runs and adopts them.
- Genesis's values are delivered recorded as the mesh's own, so 0092's never-replace rule for operator
  values does not make them unrotatable.
- Backend-issued secrets (a forge's once-only API token) enter through the vault. Non-module parties
  (the controller's logins, node agents' accounts) are answered the same way, the controller asking on
  their behalf; an enrolment token reaches the controller only as what verifies it.
- A secret with no provisioner to apply it is marked not rotatable by the mesh and refused, instead of
  a restart reported as done. Unused password generators in six provider clients are removed, and a
  catalogue scan checks no module mints.
- Rotation's lock-out cases (offline reader, bus account owner, restarted provisioner) are recorded as
  open, with overlap and re-confirm-with-safeguards as the two answers, to be chosen before acceptance.

0110, 0111 and 26 are marked proposed: they changed in meaning and are under review, and an accepted
record must not rest on proposed ones. To-be 23 and the glossary are restored to main; they change when
these records are accepted.
2026-09-25 23:47:26 +02:00

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---
topic: what runs on it
status: proposed
date: 2026-09-25
deciders: jochen
reconstructed: false
---
# 113. The vault makes every shared secret, a provider makes resources and data, and the mesh carries both
## Context
**A shared secret comes into being many different ways today**, counted across the catalogue and the
controller on 2026-09-25:
| kind | made by | used by |
|---|---|---|
| a credential between a consumer and a provider | the controller | 19 modules |
| a module's own secret (`own-secrets`) | the controller, as a random value nothing owns | 54 modules |
| a module's broker account | the controller, but only when a person runs a separate command; otherwise the random value above, which cannot work ([issue 095](../04-ISSUES/095-a-module-assigned-after-genesis-has-no-broker-account/00-report.md)) | 49 modules |
| a node's and the builder's broker accounts | the controller, each in its own code path | every node, the builder |
| an enrolment token | the controller | every node joining |
| a `secret` from the vault | the controller mints it, and the vault only records it ([ADR 0085](0085-a-secret-is-a-provision.md), as amended) | 6 modules |
| a value an operator accepts | a person ([ADR 0092](0092-an-operator-delivers-a-pair-credential.md)) | where accepted |
| a licence for model access | a separate controller context with its own store | model consumers |
| the foundation's root secrets | genesis, sealed to the operator key | the foundation |
**The vault was built to end the second row, and did not.** ADR 0085 says a module's own secret
*"stops being a generated value that nothing owns"*. 54 modules still use one, and 6 use the vault.
The replacement was added and the old path was never retired.
**ADR 0085 considered and rejected making the vault the only maker**, because *"the controller must
mint in order to deliver any provision — the vault's own credential among them"*: the vault cannot
make the credentials that exist before it does. That objection is real, and this record has to answer
it rather than step around it.
**Rotation has gaps.** To-be 13 makes rotation one command, all-or-nothing, with a stated window in
which a consumer cannot authenticate. A consumer restarts only if its definition remembered to say so;
a container fed by an env-file is not recreated when that file changes
([issue 103](../04-ISSUES/103-a-container-is-not-recreated-when-a-file-it-reads-changes/00-report.md));
and some secrets are read only when a service first initialises, where a restart changes nothing.
**And providers cannot answer with data.** [ADR 0048](0048-a-provider-creates-the-credential-the-mesh-minted.md)
left *"delivering provider-generated data back to a consumer"* to a separate decision. The analytics
provider's site id and the DNS provider's record have no way back, and say so in their code.
## Considered Options
**1. Keep the controller minting, and tidy the paths.** Rejected. The paths are the problem: each is
made, kept, rotated and audited differently, and tidying keeps them all.
**2. Every provider mints its own secrets, with one shared function in the SDK.** Rejected. Generation
becomes uniform, but custody stays spread over every provider's machine, so rotation, audit and the
operator's break-glass copies cover only some secrets. Each SDK language needs its own implementation.
**3. Raise the vault first at genesis, so it makes even the first secrets.** Rejected. The vault is
built on the shared runtime base, which the installation makes only after the store, the broker and
the controller exist, and the vault learns what to answer from the controller over the bus. Running
it first means reordering the whole installation and giving the vault a second way of being asked.
**4. The vault makes every shared secret; genesis delivers the first ones to it.** Chosen. It answers
0085's objection with a mechanism the mesh already has: a value delivered to the vault.
## Decision
**There are two kinds of secret, and each has one rule.**
- **A shared secret** is a value more than one party must hold: a password, a token, an API key. **The
vault makes every one.** Nothing else in the mesh generates a shared secret.
- **A private key** is made where it is used and never leaves: a node's sealing key, the operator's
key, the mesh's certificate authority. This is not a second way of making secrets. A private key any
other party ever held would no longer be private.
**Every shared secret is a `secret` requirement, answered by the vault:**
- a **credential between a consumer and a provider**. A provision's contract declares *for each
consumer, one secret*, and resolution expands it into one requirement per consumer. So gitea
requiring a database makes the database's provider require a secret for gitea, and the vault
answers it. The provider's own code does not change: it is handed a login and a password, as today;
- a module's **own secret**. `own-secrets` is retired;
- every **broker account** on the mesh's bus: a module's, a node agent's, the builder's, the
controller's. The broker holding `mesh-broker` carries the mesh's bus
([ADR 0110](0110-a-seat-is-a-module-assignment-from-a-closed-set.md)), and its own provisioner creates
each account from the vault's secret, like any provider. The controller no longer creates accounts,
and there is no separate command to forget;
- an **enrolment token**. The vault makes it; the operator receives the token, sealed to the operator
key, to hand to the joining machine; the controller receives only what it needs to verify it, never
the token itself;
- a **secret operator value**, such as an external API key, which the operator delivers to the vault
([ADR 0092](0092-an-operator-delivers-a-pair-credential.md)). A licence's credential is one of these.
What the licences context adds, refreshing a token, is provider behaviour, decided in its own record;
- a **secret a backend issues itself**, such as an API token a forge hands out exactly once when asked.
The vault cannot make that value. The module that received it delivers it to the vault, which keeps
it and provides it like any other; rotating it means asking the backend again.
**Parties that are not modules take the same path.** The controller's own store login and bus account,
and each node agent's bus account, have no definition to require them. The controller asks the vault
on its own behalf, or a node's, and the vault answers the way it answers any requirement: made by the
vault, sealed to the recipient, carried by the mesh. The requirement is not written in a definition,
because the controller and a node agent are the mesh itself, but it is answered no differently.
**Only the vault may provide `secret`.** An assignment providing it must hold the `mesh-vault` seat.
The parser refuses a definition that provides it and cannot hold the seat, and a pin cannot route a
`secret` requirement anywhere else, because there is nowhere else.
**A secret has recipients, and the vault delivers to each.** The database credential has two: the
provider, which *applies* it by creating the login, and the consumer, which *reads* it and presents it
when it connects. The vault hands the value to the mesh sealed to each recipient's node. The controller
and the broker carry sealed values they cannot open.
**Genesis delivers, and the vault adopts.** The vault is built on the shared runtime base, which the
installation makes only after the store, the broker and the controller are running
([to-be 21](../03-DESIGN/01-to-be/21-the-installation-in-full.md)). So the vault is installed **as soon
as that base exists**, before any other module built on it, and everything needed before that moment is
generated by genesis:
- the store's superuser, and the broker's admin in the hashed form the broker needs;
- the bus accounts of the temporary and permanent controller, the control-node's agent, the builder,
the broker's own provisioner and the vault;
- the controller's store login, and the first enrolment token.
Until the broker's provisioner runs, genesis creates the bus accounts it generated, with the broker's
admin, as the controller does today. Genesis seals all of it to the operator key, and when the vault is
installed it **delivers the values to the vault, recorded as the mesh's own**, not as an operator's.
That distinction matters: an operator's value is never replaced ([ADR 0092](0092-an-operator-delivers-a-pair-credential.md)),
and these are, because the vault can make their replacements. The broker's provisioner then adopts the
accounts genesis created. From then on the vault makes every shared secret, and genesis has made its
last one.
**A provider makes resources and data, and the mesh carries data back.** A provider's adapter may
answer with its contract's non-secret fields: a site id, a registered name. The mesh delivers them to
the consumer as resolved values. Who a consumer is stays the mesh's: a provider makes what a consumer
is *given*, never what it is *called* ([ADR 0049](0049-a-consumers-identity-fits-the-tightest-backend.md)).
### Rotation
**It is asked of the vault**, by an operator or by the vault's policy, such as a maximum age in the
secret's contract. A delivered value the vault cannot replace, such as an external API key, is not
rotated by the vault: rotating it means an operator delivering a new one.
**A secret's contract says how each recipient takes a new value:**
| recipient takes it by | example | what happens on rotation |
|---|---|---|
| **applying** it | a provider creating the login; the broker's provisioner updating an account; the store's own provisioner changing its superuser | its provisioner applies the new value; it is never restarted for it |
| **reading it at start** | a consumer reading its password when it starts | the host restarts it, or recreates a container whose env-file carries it |
A secret read only when a service first initialises cannot be rotated by a restart. Its contract marks
it applied, and a provisioner makes the change. Where no provisioner exists to make it, such as a
module's own bootstrap password, the contract marks the secret **not rotatable by the mesh**, and a
rotation request is refused, saying why, rather than restarting a service that would carry on with
the old value. The host derives which recipients read a secret at start from the requirement their
definition reads it through, so no definition declares a restart for a secret. A provider's
per-consumer secrets are applied, never read at start, so the host never restarts a provider for one.
**It is applier-first.** The vault delivers the new value first to the recipients that apply it. Each
applies it, verifies that the new value authenticates and the old one no longer does, and confirms.
**It repeats that confirmation on every reconcile pass until the vault acknowledges it**, so a lost
message costs one pass. Only after every applier has confirmed does the vault release the value to the
recipients that read it at start.
**Open: keeping readers from being locked out.** Review found three cases this rule does not survive:
- a reader whose machine is offline when an applier has already applied the new value is locked out
until it returns, where to-be 13 would have refused the rotation and kept the old value working;
- a bus account's owner can be locked out permanently, because the confirmation and the new value
travel over the bus it has just lost;
- a provisioner restarted mid-rotation no longer knows the old value, so it cannot verify that the old
value has stopped working.
Two answers are recorded, and one must be chosen before this record is accepted. **Overlap:** an
applier keeps the old and new credential valid together until every reader has confirmed the new one,
for instance by alternating between two derived logins with the adapter's existing create and remove,
which needs no change on the consumer's side. Or **re-confirm with safeguards:** a pre-check that every
reader is reachable before any applier starts, plus a special path for bus accounts.
**It is confirmed.** A rotation is shown as unconfirmed until every applier has confirmed, and every
recipient that reads at start has restarted with the new value and passed its health check, where its
definition declares one.
| step | who |
|---|---|
| asks | an operator, or the vault's policy |
| makes the value | the vault |
| carries it | the controller, sealed, appliers first |
| applies it | each applier's provisioner, which verifies and confirms on every pass until acknowledged |
| takes it at start | the host, restarting or recreating what reads it |
| confirms it | applier confirmations, then restarts and health checks, shown in `status` |
## What this changes in earlier records
On acceptance, each of these is superseded or amended by this record, not edited:
- [ADR 0048](0048-a-provider-creates-the-credential-the-mesh-minted.md) is superseded: the controller
no longer mints a provider's credential; the vault makes it. That a provider is handed its
credential and seals nothing stands.
- [ADR 0085](0085-a-secret-is-a-provision.md) is amended: the vault makes every shared secret, own
secrets are retired, and its rejection of vault-only minting is answered by genesis delivering the
first secrets. "The vault stores no plaintext, ever" stands.
- [ADR 0092](0092-an-operator-delivers-a-pair-credential.md) is amended: an operator delivers a secret
to the vault. Genesis's values reach the vault by delivery too, but are recorded as the mesh's own,
so 0092's rule that an operator's value is never replaced does not apply to them.
- [ADR 0043](0043-a-module-broker-account-is-scoped-by-emits-and-consumes.md) is amended: a broker
account is created by the broker's provisioner, not the controller. Its scoping stands.
- [To-be 13](../03-DESIGN/01-to-be/13-credentials-and-their-rotation.md),
[to-be 21](../03-DESIGN/01-to-be/21-the-installation-in-full.md) and
[to-be 24](../03-DESIGN/01-to-be/24-the-secrets-vault.md) are amended: rotation is applier-first,
derived and confirmed; the vault is installed as soon as the shared runtime base exists, and genesis
delivers its secrets to it; the vault is the only maker.
- The [glossary](../00-META/glossary.md) gains *shared secret*, *recipient*, *applies* and *reads at
start*, and *reserved provision*, once this record is accepted.
- [Issue 103](../04-ISSUES/103-a-container-is-not-recreated-when-a-file-it-reads-changes/00-report.md)
becomes a prerequisite: rotation cannot be trusted while a changed env-file leaves a container on
its old value.
## Consequences
- **The vault is on the path of every new or rotated shared secret.** Today the controller holds that
place, on the same node. A secret can no longer be made while the vault is down.
- Resolution expands per-consumer requirements from a provision's contract. The contract declares
them, never the provider's code, so what a provider requires stays predictable from the catalogue.
- The SDK's provider loop gains repeated confirmation of an applied rotation. A credential provider's
adapter is unchanged. A data provider's adapter gains a return value.
- The broker's provisioner gains every bus account, and the controller loses five separate places it
generates a secret today.
- 54 modules move from own secrets to vault requirements. Six provider clients export a password
generator nothing uses any more; it is removed, so no module can quietly start minting again.
- The installation changes order: the vault is installed as soon as the shared runtime base exists,
before any other module built on it.
- **What got harder:** a rotation waits for its appliers, and how a reader is kept from being locked
out while it does is still open (above). A secret some services read only at first start can no
longer be "rotated" by a restart that quietly changes nothing; it is refused instead.
## How it is checked
| Rule | Checked by |
|---|---|
| Only the vault generates a shared secret after genesis | A controller test: no code path generates a shared secret. A catalogue test: no module's code generates one, found by scanning for generation calls, with none exempt. An installer test: genesis generates exactly the list above and delivers it to the vault, recorded as the mesh's own. |
| A private key is made where it is used | A test per key: a node's sealing key never leaves the node, the operator's private key never enters the mesh, and the certificate authority's private key never leaves the controller's identity store. |
| Only the vault provides `secret` | The parser refuses a definition providing `secret` that cannot hold `mesh-vault`, and resolution refuses a pin on a `secret` requirement. |
| Parties that are not modules take the same path | Controller tests: its own store login, its bus account and a node agent's bus account are each made by the vault and delivered sealed; an enrolment token reaches the controller only as what verifies it. |
| A backend-issued secret enters through the vault | A vault test: a value delivered as issued is provided like any other, and rotating it is refused as the vault's act. |
| A secret with no provisioner to apply it is not rotated by restart | A vault test: rotating a secret marked not rotatable by the mesh is refused, naming why. |
| A provider's per-consumer secret comes from the vault | A resolution test: a consumer requiring a database expands to a secret requirement for it, answered by the vault and delivered to both recipients. |
| Values are carried sealed | A controller test: each recipient's copy opens with that recipient's node key and no other; neither the controller nor a message on the broker can open one. |
| Own secrets are retired | A catalogue test: no definition declares an own secret, with a declared list of exceptions that shrinks to empty. |
| Bus accounts come from the broker's provisioner | A resolution test: assigning a module that speaks on the bus yields its account, created by the broker's provisioner with no separate command. |
| An operator's value is never rotated by the vault, and genesis's values are | Vault tests: a rotation request on an operator's external key is refused, naming the operator; the same request on a value genesis delivered makes a replacement. |
| Rotation is applier-first | A rotation test: readers are not sent the new value until every applier confirms. How lock-out is prevented is open, and its check is written when that is decided. |
| Restarts are derived from how a secret is read | A host test: a secret read at start restarts its reader, and recreates a container whose env-file carries it; an applied secret restarts nothing. |
| Rotation is confirmed | A rotation test: an applier confirms only after the new value authenticates and the old one does not, and the rotation shows unconfirmed until every reader restarted and passed its health check. |
| A provider answers data back | A lab test with a consumer requiring analytics: the provider's site id reaches it as a resolved value. |
## References
- [ADR 0048](0048-a-provider-creates-the-credential-the-mesh-minted.md): the decision this supersedes,
and the return path it left open
- [ADR 0085](0085-a-secret-is-a-provision.md): the vault, and the objection this record answers
- [ADR 0092](0092-an-operator-delivers-a-pair-credential.md), [ADR 0049](0049-a-consumers-identity-fits-the-tightest-backend.md),
[ADR 0043](0043-a-module-broker-account-is-scoped-by-emits-and-consumes.md): delivered values,
identity, and broker accounts
- [ADR 0112](0112-a-module-definition-names-no-node-mesh-or-path.md), [to-be 27](../03-DESIGN/01-to-be/27-a-module-requires-the-mesh-resolves.md):
everything a module needs is a requirement
- [Issue 095](../04-ISSUES/095-a-module-assigned-after-genesis-has-no-broker-account/00-report.md),
[issue 103](../04-ISSUES/103-a-container-is-not-recreated-when-a-file-it-reads-changes/00-report.md): what fails today
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