jschoubben
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HQ held only the to-be. Every reader had to already know the system the decisions were about, and an as-is claim had nowhere to live except inside an intention. Adds 02-DESIGN/00-as-is — eleven documents written from the implementation and the operational record, not from intent, including the parts nobody would choose again. The two existing designs move under 01-to-be. Layers are declared in frontmatter and never mix: a design that ships does not move, its as-is counterpart is written, and both stand. Back-fills adr/0001-0014 for decisions taken in implementation and never recorded — the broker, the module abstraction, the mesh database, managed files, provisioning, migrations, the workspace removal, failing loudly, the constitution, application placement, linking, the employee model, the artifact, the three silos. Each marked reconstructed, dated from the history, and citing the evidence it was recovered from. The two existing records renumber to 0015 and 0016 so the ledger runs oldest first; 0017 extends 0015 to modules outside the core, principle only — the domain list is deliberately not invented here. how-we-build.md becomes the source of the mesh constitution, with a sync playbook, so the enforced copy stops being the only one that is true. Process becomes explicit: five playbooks, eight thin skills that defer to them, a repository map, and AGENTS.md with CLAUDE.md as its include. The five Observations become 04-ISSUES 001-005 where they can be owned and closed. 006 is new and uncomfortable: HQ is not indexed into the knowledge base. That claim is what decision 27 rests on, it was never checked, and the README now says so instead of repeating it. Also corrects the ADR index into something generated, the "02-DESIGN is empty" claim, the VISION.md pointer that did not survive the repo split, and a note asserting the symlink rule was contradicted — it was a misreading; the rule forbids hand-made links, the installer links by design.
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status, date, deciders, reconstructed
| status | date | deciders | reconstructed |
|---|---|---|---|
| accepted | 2026-05-14 | jochen | true |
6. Schema and state changes are numbered migrations, in the same language as the code
Reconstructed after the fact from the evidence cited below.
Context
Modules own persistent state. That state has to change as they change, across nodes that are at different versions, some of which have data that predates the change.
Two things were being done that do not survive contact with a second node. Schema was created at startup, so what a table looked like depended on which version last started. And migrations were shell scripts, so they could not use the types, connection handling or helpers the module already had, and were not compiled or checked with it.
Considered options
- Startup SQL / create-if-missing. Rejected. It converges only for a node that started with the newest version. A node that never restarts never migrates; a node that restarts on an old version can undo a change.
- Shell migrations. Rejected. Unchecked, untyped, and a separate dialect from the module they belong to. Also, as later discovered, packaged differently — and therefore occasionally not packaged at all.
- Numbered migrations in the module's own language, compiled with it. Chosen.
Decision
Every schema or state change is a numbered migration file, written in the same language as the module and compiled with it. There is no startup schema creation and no ad-hoc statement.
Rules that come with it:
- The initial migration is frozen once it has run anywhere. It is never modified; a change is a new number.
- Every statement is idempotent — guarded so that re-running is safe.
- A change needs both a baseline for a fresh installation and an incremental migration for installations that already exist. Code referencing a column requires that the migration creating it exists.
- Migration numbers are unique. A duplicate prefix is a defect, not a style issue.
Consequences
- A node at any version converges to the current schema by running the migrations it has not run.
- Migrations are checked by the same compiler as the code, and a migration that does not compile fails the build rather than the deployment.
- The rules are enforced unevenly. Duplicate prefixes have shipped repeatedly and been fixed by renumbering afterwards; the mesh now validates for them, which is the check this rule needed in order to be real.
- A migration directory is a feature like any other, which means it is packaged like any other — and when packaging is wrong, migrations silently do not ship. This has happened.
- Freezing the initial migration means a fresh installation replays the entire history. That cost grows and nothing currently bounds it.
References
fix(agents): convert workflow migrations to TypeScript(#50), 2026-05-14.feat(dev_validate): guard against duplicate migration numeric prefixes(#379), 2026-06-26 — the rule acquiring a check.- Knowledge base:
migrations/schema-drift,noxflow/troubleshooting/migration-number-collision. - Packaging failures:
troubleshooting/shell-migrations-never-packaged,troubleshooting/provision-migration-never-applied.