The mesh's own seats said who does a job and nothing about what may be said to
them or by them, and that gap showed up three times in one day looking like three
different problems: a build machine with three audiences for one outcome and no way
to derive a grant for any of them; an event genuinely about a role with nowhere to
live but the namespace of whichever module holds that role today; and a catalogue
catching up on builds, where every option needed a grant the design refuses.
One cause — the mesh has roles it cannot describe. So the `mesh-*` seats take the
same three fields a module's seat has, and the machinery that already derives
authority, queues and consumers from a declared seat does it for these too.
Builds become work submitted to a role, and `mesh.build.request`,
`mesh.control.built` and the BUILDS stream retire. A work queue shared by several
build machines is exactly what a seat's `accepts` is, so a second mechanism for it
was two places a permission could be wrong. The outcome is the seat's own event,
which means one publish still reaches whoever asked, the controller that records it
and the catalogue that places it — the fan-out a shared exchange gave for free,
written as a subject the mesh derived rather than a topology somebody configured.
That also avoids the grant that ruled out the alternatives: no holder needs
permission to publish into an asker's inbox.
The blocking gap is now named rather than incidental: the shared library has no way
for a module to publish on a seat. The build machine is Go and reaches the bus
directly, so it is unaffected; the artifact-store event waits.
Every module named its events the way the old bus spelled a routing key, so on the
new bus every cross-module subscription pointed at a namespace nobody publishes to.
Nothing failed — the services started and none of them reacted. Converted, and the
rule now has checks at both scales: at registration for one manifest, and as a test
across the whole catalogue where a consumed event's emitter is present.
It was larger than the report said, in two directions nobody had looked. Forty-three
files of module code pass the event name at runtime, so the code mattered as much as
the manifests. And both clients had to learn the mapping — without that, converting
the modules would have broken the mesh that is actually running, which is the
opposite of what fixing this was for.
Design 29 gained three things it did not say: what a wildcard is (`*` for one name,
`**` for the rest, spelled the mesh's way and derived to each bus's own), that an
event about a role belongs on the seat and why that is not yet possible, and how the
rule is checked — because "a subscription that matches nothing is silence" is exactly
why nobody noticed thirty-seven manifests being wrong the same way.
4.2 and 4.3 are unblocked. The catch-up half of 4.5 is not: it is a decision, and it
narrowed rather than closed. It cannot be a reply to a module's inbox, because that
needs the blanket grant design 25 §4 refuses.
Two things. A paragraph from the superseded 0117 survived beside the 0119
correction that reversed it, so §5 said both that the amqp interface
retires and that it does not. The stale one is gone.
And the framing. §1 opened with "the bus carries five kinds of traffic
today, and this design keeps the five", with a column mapping each to the
queue it used to be — which describes the mesh's nervous system as a port
of something that did a fraction of this. It now says what the bus is: a
role addressable without knowing its holder, the mesh's own state, work
that queues until somebody can do it, and permissions derived from what a
module declared. Conditions, observation and a person's client land there
too as they are built.
Glossary gains `bus` and `the deprecated broker`, with a note on why not to
say "compatibility broker" or name it after a protocol — the second invites
exactly the backwards framing this commit removes.
The manifest already uses serves for a provision's facts, so a module's
tools take their own key. Declaring them is itself new — until now a
module's tools existed only in a runtime environment variable.
Storage is not a property of a subject — a stream is a separate object that
covers one — so the question is always how many streams, not which topics
are durable.
Three facts decide it, two of them verified rather than assumed: NATS
refuses overlapping streams instead of merging them, so a shared stream
plus a per-module one is not available at all; a filter cannot express an
exception; and a stream per module turns one cross-module consumer into one
per module. So one stream, with per-subject caps for the fairness that
matters. Per-module age is genuinely unavailable, and a module that needs
it declares a seat.
Design 29 said no module requires the bus. The catalogue disagrees: 49 of
72 modules take a broker credential and 23 do not, so an ambient connection
mints an account for a third of the catalogue that never speaks — and the
49 each hand-write the path it lands at, which is provisioning done badly
by hand.
The bootstrap argument that made it ambient was narrower than it looked.
"A provisioner needs an account before it can run" is true of a provisioner
process and says nothing about a provision the controller answers, and the
controller is not waiting on a bus account to compose one.
So: the mesh-broker seat delivers mesh-bus; a module requires it and gets an
address, a sealed credential and the trust to verify the server; a module
that requires nothing has no account at all. The requirement delivers the
connection, the declarations shape the authority, and declaring a subject
without requiring the bus is refused as incoherent.
mesh-bus and nats are deliberately two names: a module may run its own NATS
as a backing service exactly as one provides amqp, and a manifest saying
"nats" would otherwise mean either the mesh's nervous system or a private
queue.
The seat's Delivers was wrong twice today — amqp, then empty — and the
comment says so rather than reading as though it were always right.
0117 went a step further than it had grounds for. It was right that the bus
is the only bus, and wrong that the amqp interface must therefore retire —
because it conflated two reasons to want a broker. Using one to reach
another module is a second bus and stays refused. Needing an AMQP broker as
a backing service, the way something needs a database, is ordinary, and
forbidding it would make the mesh unable to run normal software while
calling that architecture.
So the broker becomes a plain provider module: no seat, not foundation,
never raised at genesis, no retirement condition. lavinmq now claims nothing
and provides amqp; nats claims mesh-broker and provides nothing.
The rule that survives is about direction, not software: inter-module
communication goes over the bus. A module may hold a broker for itself; it
may not use one as a channel to another module. That is a review judgement
where 0117 could have used a parser, which is the honest cost.
0106's progressive insight was itself wrong and is corrected by a second one
there — nothing moves off the old broker, so its "one purpose" sentence does
not become true, it is just not what that server is.
The insight check needed two fixes it found itself: a date may carry
trailing words, and a bold run with a link is discussing an insight rather
than marking one. All four bad shapes still fire.
29 put a module's events and tools in one namespace, 25 kept mesh.events.*
and mesh.tools.*. One namespace is right — a module's authority over its own
name becomes a single pattern the server enforces — but it needs a kind
token, because a stream is a subject filter and mesh.mod.*.> would persist
every tool call in the mesh. Tools stay on core NATS for the reason 25
already gives.
So: mesh.mod.<module>.event.<name>, .tool.<name>, and seats the same shape.
Versioning: additive is free; a breaking change is refused while callers are
bound, and the refusal names them, because the mesh already holds the uses
graph; a real break versions the subject, not the seat name, so the role
does not fork; binding is a recorded pin, not a drift to whatever is newest.
Semantic change stays open — no fingerprint sees it, and saying so beats
implying the check is complete.
Provisioning: a provisioner's create/remove/holds IS a serves protocol, so a
provision interface is a seat that also delivers a credential — which is why
design 26 already allowed that. The per-consumer resource is what stops the
two collapsing into one.
Secrets: sealed, so the bus is never trusted with plaintext — but sealed is
not enough, because a stream persists and a durable ciphertext is an archive
the day a key leaks. So a secret never enters a stream: core request/reply
only, and a declaration names a secret rather than carrying one, which is
0098's fetch-don't-store applied where carrying is worst. The vault's own
credential and the bus's own accounts are the two bootstrap exceptions,
resolved the way 0067 resolves the control plane.
Also rewrote the addresses paragraph, which was too compressed to follow:
on-bus addresses disappear because nothing stores them, off-bus ones are
untouched and still 0098's problem, and the bus's own address is the one
that cannot be a subject.
The architecture 0117 opened needs a module to offer a service as a role on
the bus — one holder, addressed by what it does. A closed table in the
controller cannot express that: a capability a module contributes would
require changing the mesh itself.
But 0110 closed the set for a good reason — nothing could say what seats a
mesh had, and the hand count came out at eleven of thirteen. That argues for
enumerable, not hardcoded, and 0110 weighed free-form against a fixed table
without considering a third option: closed at any moment and derived from
the catalogue. A derived list cannot drift, which is how the count broke.
So: the mesh's seats stay the mesh's, reserved by the mesh- prefix so the
prefix is the rule and there is no list to maintain; ten seats are renamed
to restore 0079's convention; everything 0110 decided about what a seat IS
survives untouched.
Design 29 carries the declaration model: three namespaces, subjects derived
from local names so a manifest survives the wire changing, queues never
declared, five relationships (the job and state shapes 0041 had no room
for), and the build-publish-deploy lifecycle with hard, soft and build-time
dependencies distinguished.
0041 gets a progressive insight: "no per-consumer setup, only a
subscription" was a fact about a topic exchange, and a JetStream durable
consumer is a real object someone creates.
WBS 1.3/1.4 were wrong and say so: streams come at registration and
consumers at assignment, so only the foundation set belongs at genesis.
jschoubben