jschoubben
7a20358113
A tier test as a decision procedure — five ordered questions, first match wins — so placement is answerable rather than argued. Postgres was the test case and the naive answer is wrong. Not twice, once: the control plane cannot exist without a relational store, so it is tier 1 and lives in hal-substrate/store/postgres. What differs between the mesh's own database and a project's is not the module but how that instance is brought up — pinned bundle applied by the host, versus the ordinary delivery and provisioning path. Tier is a property of the module; the bundle is a property of the mesh's own instance. The naive answer would also have made substrate reach up into the catalogue, which the dependency rule forbids. Working the test across the catalogue surfaces a third fate that neither of research 005's options covers, and it is the most common one: absorbed into the host, ceasing to be a module at all. That explains 005's one positive measurement rather than confirming it — the reachability cluster is not four modules that should be one domain module, it is four facets of one thing the host should own, expressed as modules because a module was the only unit available. Under this skeleton the overlay and firewall modules stop existing. It also partly answers the silent fifty: several are host concerns, so silence was the right signal and grouping was the wrong inference. Flags rather than settles: the identity provider is a genuine boundary case (four substrate services or five), and absorbing six concerns into a binary whose argument is that it has no dependencies is the skeleton's biggest unproven claim.
84 lines
4.8 KiB
Markdown
84 lines
4.8 KiB
Markdown
---
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status: active
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initiated: 2026-08-23
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touches:
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- 02-DECISIONS/0015-mesh-brokers-nodes-host-agents-think.md
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- 02-DECISIONS/0017-modules-outside-the-core-are-grouped-by-domain.md
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- 03-DESIGN/00-as-is/00-overview.md
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- 03-DESIGN/01-to-be/00-work-breakdown.md
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became: []
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---
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# 006 — The mesh designed from nothing
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## What is being investigated
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What the mesh would look like if it were laid out today, with the requirements known and none
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of the accumulated shape — expressed as a **skeleton**: repositories at the root, modules
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inside them, and whatever turns out to be the right leaf unit below that.
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The deliverables are [`skeleton.md`](skeleton.md) — tiers, repositories and the four design
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moves — and [`code-skeleton.md`](code-skeleton.md) — the tier test, what a module looks like on
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disk, and where today's catalogue lands.
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## Why
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Every structural decision so far has been a **correction**: eight contexts replacing thirty-three
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modules ([ADR 0015](../../02-DECISIONS/0015-mesh-brokers-nodes-host-agents-think.md)), domains
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replacing single-function modules
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([ADR 0017](../../02-DECISIONS/0017-modules-outside-the-core-are-grouped-by-domain.md)). A
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correction inherits the frame of the thing it corrects, and two of the mesh's oldest problems
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look unsolvable from inside that frame:
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- **The bootstrap circularity.** The mesh needs a database, a bus, a registry and an identity
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provider. Those are modules the mesh installs. The mesh cannot install them before it exists.
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This has been worked around repeatedly and never designed away.
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- **Participation requires privilege.** Everything assumes root on a machine whose packages and
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services the mesh owns. A phone cannot participate on those terms, and neither can a machine
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someone else administers.
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Designing from nothing is a way to find out which parts of the current shape are requirements
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and which are residue.
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## The requirements this is designed against
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Stated by the operator, recorded here so the skeleton can be checked against them rather than
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against taste:
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1. The mesh manages multiple computers — **full control**, through modules installed to nodes.
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2. Mesh state lives in a **database**: which modules on which nodes, logs, configuration.
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3. Configuration has **several touchpoints** — tool surface, web interface, others — all hosted
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by the mesh itself.
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4. **Connectivity** is core: every node reachable from every other over a shared overlay, some
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nodes publicly exposed, firewalls configured.
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5. The mesh **hosts applications** — and requires some of them itself. This is the circularity.
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6. **Arch Linux only for now**; ideally any device, including phones, on lighter terms.
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7. The end goal is to **operate an IT company** on it — development, design, deployment, full
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circle, self-hosted. Personal cloud infrastructure.
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8. **Agents make it self-improving and self-healing.**
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9. It is **end-to-end testable on one machine**
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([ADR 0016](../../02-DECISIONS/0016-a-lab-node-is-a-virtual-machine.md)).
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## Status
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A first skeleton exists, with four design moves that the current shape does not have. It is
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`active` because two of them are unproven and one contradicts a record that is already
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accepted.
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**Finding worth stating up front:** [ADR 0015](../../02-DECISIONS/0015-mesh-brokers-nodes-host-agents-think.md)
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names nine bounded contexts and **none of them owns connectivity** — no overlay, no resolution,
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no firewall, no ingress. Requirement 4 has no home in the accepted decomposition, while
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[research 005](../005-domain-grouping/analysis.md) found reachability to be the *only* part of
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the catalogue where modules genuinely change together under one intent. The skeleton adds it.
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## Open questions
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| Question | Why it is open |
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|---|---|
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| Does the record — the event log contexts integrate through — belong to the substrate or the control plane? | It is infrastructure by shape and domain by content. Placing it wrong reintroduces a circularity. |
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| One repository per tier, or per context? | Already open from ADR 0015 as "catalogue destination — one repository or many". The skeleton assumes per tier and does not settle it. |
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| Does an unprivileged node earn a place in the inventory, or only a presence? | Decides whether "node" means one thing or two. |
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| Does absorbing overlay, filtering, packages, supervision and the container runtime make the host too large? | It is the skeleton's biggest unproven claim. A binary whose whole argument is that it has no dependencies now carries six concerns. |
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| Four substrate services or five? | The identity provider passes the tier test only if the control plane delegates authentication rather than doing it natively. |
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| Does `feature` survive? | The skeleton splits it in two and argues the conflation is what makes the delivery pipeline hard to reason about. Unproven. |
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