Files
hq/02-DECISIONS
jschoubben 86a084b7ff The mesh bus is required, not ambient
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.
2026-09-26 21:17:21 +02:00
..

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 A superseded record has its status: changed and gains a pointer to what replaced it — its reasoning is never rewritten. The reasoning that was rejected is the expensive half to rediscover.

Progressive insight

A record is a decision, not a snapshot of everything that was true the day it was written, and those two fail differently. A fact a record asserted can turn out to be wrong while the decision it supports stays right — a count taken before anyone measured, a file named that does not exist, a proof attributed to a step that cannot run it. Superseding a record for that buries a correct decision under a second one, and teaches every reader to first work out which of two records is live. Done a few times, the reading order stops being one.

So: a correction of fact that leaves the decision standing is made in the record, in place, marked and dated.

Progressive insight — YYYY-MM-DD. What was found, what the record said before, and what it says instead.

Three conditions, all of which hold:

  • It corrects a fact, not a judgement. That a suite does not exist is a fact. That building it is the wrong order is a judgement, and judgements supersede.
  • It adds; it never quietly replaces. Where body text changes, the note says what stood there before, so a reader who followed a citation to the old wording can find out what happened to it. A correction nobody can see is indistinguishable from a record that was always right, which is the failure the immutability rule exists to prevent.
  • The decision, the options weighed and the consequences stand untouched. If the correction changes what was decided, which alternatives were rejected, or a consequence another record relies on, it is not an insight — write the superseding record.

What still supersedes, without exception: reversing a decision, changing its scope, rejecting an option it accepted, or making a consequence false that a later record cites. The test is not how large the edit looks in a diff; it is whether a reader who acted on the old text would now be wrong about what was decided rather than about a detail the decision did not rest on.

How this is checked. 00-META/checks/records.py requires every insight to be marked in the form above and dated no earlier than the record's own date: — an unmarked edit is a rule violation the reviewer looks for in the diff, and a marked one is legible in the record itself. The git history is the backstop, not the record of intent; the note is the record of intent.

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

Its tiers, from the bottom up

What runs on them, and how it gets there

How it is built

How it is checked

How we work