jschoubben
84f4425fd6
Two things found by trying to build tier 2. The substrate design asked whether the message broker has to be running before the control plane, and framed it as depending on whether the control plane's own parts talk to each other over it. They do not -- it is one process -- so under that framing the broker stays out of the bundle. The framing cannot answer the question. What decides it is how the control plane reaches a node, and the answer was already decided: only ever over the link, and the link is the broker. So provisioning the broker would require the broker. The first node does not escape this by being local, because it enrols the ordinary way, by dialling the broker at the address in its token -- which was deliberate, and worth keeping. The bundle is two images now. The record says what that costs, including a certificate the broker needs at a moment when there is no mesh to issue one. The language had never been decided for tier 2. Go, for the same reason the host is: the bundle pins this image by digest and runs it where nothing can check it, so the image should hold the program and nothing else. Also corrects something already built: the bootstrap created one database and called it 'mesh'. ADR 0008 grants a context only what it exclusively owns and ADR 0006 says the mesh database names a thing that will not exist. One database per context, so one today, called inventory.
6.0 KiB
02-DECISIONS
Architecture decision records — the "why" trail behind the rules in
00-META and the specifications in 03-DESIGN.
Numbered 02 because a decision precedes the design it authorises. Research concludes,
the decision is recorded here, and only then is the design written. Following the folder
numbers walks the process in the order it happens.
One file per decision, numbered, never deleted. A superseded record has its status: changed
and gains a pointer to what replaced it — its text is never edited. The reasoning that was
rejected is the expensive half to rediscover.
The records run in the order the decisions were taken, oldest first.
Every decision is a record. There is no ledger and no index file — if a decision is worth
recording it is worth a record, and if it is not worth a record it is not recorded
(ADR 0019). A "decision" small enough to be one line is
almost always a rule, and a rule belongs in
00-META/how-we-build.md, where it is enforced and keeps the
incident that earned it.
Frontmatter
---
status: proposed | accepted | superseded
date: YYYY-MM-DD # when the decision was taken, not when it was written down
deciders: name
reconstructed: true|false # true when the record was written after the fact from evidence
superseded-by: # 02-DECISIONS/NNNN-....md, when status is superseded
extends: # 02-DECISIONS/NNNN-....md, when this record widens an earlier one
---
Body
# N. Title in plain language
## Context what was true, with evidence
## Considered Options numbered, each with why it was rejected
## Decision what was decided
## Consequences what follows, including what got harder
## References commits, pull requests, knowledge-base entries, prior art
State evidence, not assertion. "Zero of 124 modules declare brain as a dependency"
outranks "the dependency rule is not followed".
Reconstructed records
Records 0001–0014 were written on 2026-08-23, after the decisions they describe. Records 0015 onward were taken as records. Those
decisions were taken in implementation rather than in a document; the records state what was
decided and the evidence it was decided from, and each carries reconstructed: true and says
so in its first lines.
A reconstructed record is not a transcript. Where the deliberation is not recoverable, the options section states what the alternatives were and why the chosen one won on the evidence available — not a discussion that did not happen. Where a date is not establishable it says so rather than guessing.
Index
A number identifies a record and never changes. Records are referenced from outside this repository — code comments, commit messages — so a number that moves invalidates them silently. Renumbering once cost 96 references across two code repositories, and that is why the numbers are now fixed.
So the folder is in creation order, and the reading order lives here. It is generated from
each record's topic: and written, because a reader looking at the folder on a forge sees the
folder rather than a command. The objection to a written index is that it drifts — which is
answered by checking it rather than by refusing to write one:
python3 00-META/checks/index.py --write regenerate
python3 00-META/checks/index.py fail if stale
What the mesh is
- 0001 — The mesh brokers capabilities; nodes host; agents think
- 0002 — Nodes communicate over a message broker, not over HTTP
- 0003 — An agent is a persistent employee, not an instance of a pool
Its tiers, from the bottom up
- 0004 — A node, and how it joins
- 0005 — The node host
- 0006 — The substrate and the control plane
- 0007 — Connectivity
- 0008 — A context owns its store, exclusively
- 0024 — Running the control plane (proposed)
What runs on them, and how it gets there
- 0009 — Modules and the graph
- 0010 — Delivery
How it is built
- 0011 — Managed files are generated onto nodes and never edited there
- 0012 — The mesh creates no symlinks — a derived file is a copy
- 0013 — Schema and state changes are numbered migrations, in the same language as the code
- 0014 — No workspace — each module is a standalone package consuming published dependencies
- 0015 — Applications live in their own repository; the monorepo is for the mesh
- 0016 — The lab
How it is checked
- 0017 — A test defends a decision
- 0018 — A picture of a system is read from the system, never from what asked for it