jschoubben
77f3a4cea7
Every remaining cluster merged. Each was one design that had been split across
several records because it was worked out over days rather than at once.
the node host 8 -> 1 applies not decides, depends on nothing,
per operating system, root service, the
launcher, episodic, what a declaration is,
actions from the bundle only
a node and how it joins 4 -> 1 what a node is, joining, the link as
security boundary, the enrolment token
modules and the graph 7 -> 1 everything is a module, no domain modules,
three edges, provisioning, the core library
substrate and control 6 -> 1 the test, seven contexts, one control plane,
plane the authority is not a database, the named
products, the pinned bundle
connectivity 3 -> 1 a route is a grant, reachability declared,
filter rules
delivery 5 -> 1 reconciliation not a pipeline, artifacts,
the three silos, a failed step, the verdict
the lab 5 -> 1 (earlier)
how this repository 10 -> 1 (earlier)
works
Nothing was dropped. Each consolidated record carries the reasoning of the ones
it absorbs -- the measurements, the incidents, the alternatives rejected --
because that reasoning is the only reason to keep a record at all. What is gone
is the fragmentation: eight files to read to understand tier 0, when tier 0 is
one component.
The four superseded records went too. They existed to point at their
successors, and the successors now contain what they said.
The checker made this safe. Each merge left dangling links -- 38 files after
the host merge alone -- and it named every one. Nothing was found by reading,
and a manual pass would certainly have missed some, including references inside
AGENTS.md which every session loads.
108 lines
5.0 KiB
Markdown
108 lines
5.0 KiB
Markdown
---
|
|
layer: as-is
|
|
status: implemented
|
|
code: [hal]
|
|
updated: 2026-08-23
|
|
decisions:
|
|
- 02-DECISIONS/0044-modules-and-the-graph.md
|
|
- 02-DECISIONS/0018-the-mesh-creates-no-symlinks.md
|
|
---
|
|
|
|
# The node runtime, and how a node comes into being
|
|
|
|
Every node runs the same runtime. What differs is its assignment.
|
|
|
|
## Two modes, coexisting
|
|
|
|
The runtime runs in two modes at once on any node that needs both.
|
|
|
|
**Daemon** mode is a headless consumer: it connects to the broker, consumes the node's request
|
|
queue, routes each request to a local capability, and emits the node's lifecycle events. This
|
|
is what makes a node a participant — it is reachable whether or not anyone is logged in.
|
|
|
|
**Interactive** mode exposes the node's capabilities to a session on that machine over a local
|
|
protocol. Its capability surface is larger, because it includes stand-ins for every capability
|
|
discovered on peers.
|
|
|
|
The two are the same code with the same catalogue. A capability is written once and is
|
|
available to both.
|
|
|
|
## Anatomy naming, and what it obscures
|
|
|
|
The runtime's components are named after brain anatomy: an entry point that bootstraps, a
|
|
headless listener, an interactive surface, an installer daemon, and a provisioner daemon.
|
|
|
|
This is the mesh's most-cited naming problem and it belongs in the as-is layer because it is
|
|
what a reader will actually encounter. The names are evocative and describe nothing: the most
|
|
suggestive word in the system names the node runtime, and the component whose manifest says
|
|
"mesh messaging" is documented elsewhere as the interactive runtime. Anatomy makes attractive
|
|
names and poor boundaries.
|
|
|
|
[ADR 0015](../../02-DECISIONS/0015-mesh-brokers-nodes-host-agents-think.md) replaces this with names
|
|
taken from what each part owns. Until then, this is the vocabulary in the code.
|
|
|
|
## Starting a module
|
|
|
|
For each assigned module the runtime, at startup:
|
|
|
|
1. Reads the manifest, if there is one — a flag module has nothing to read.
|
|
2. Skips a module's capabilities if a variable they require is unset. This is quiet by design
|
|
and hard to distinguish from a module that has no capabilities.
|
|
3. Loads the capabilities the module carries.
|
|
4. For a service module, ensures it is installed and running.
|
|
|
|
Installation is idempotent and does the unglamorous work: ensure the runtime directory,
|
|
reconcile the link from the catalogue's definition into it, generate the environment, run any
|
|
outstanding local migrations, create data directories with the right ownership, then start the
|
|
service under supervision.
|
|
|
|
**The installer is the only thing that creates a link** ([ADR
|
|
0011](../../02-DECISIONS/0018-the-mesh-creates-no-symlinks.md)). It reconciles rather than assumes: a
|
|
missing link is created, a stale one repointed, and a real file found where a link belongs is
|
|
adopted into the node's override area and replaced. Nothing else — not a hook, not a fix, not a
|
|
person debugging — creates one.
|
|
|
|
That is the as-is. The intent is to remove linking altogether and derive a real file instead,
|
|
which the reconciliation machinery already makes possible
|
|
([ADR 0018](../../02-DECISIONS/0018-the-mesh-creates-no-symlinks.md), proposed). What is described above
|
|
is what runs today.
|
|
|
|
## Supervision
|
|
|
|
Services run under the host's init system via a templated unit, one instance per module. It is
|
|
a thin layer: the unit starts and stops a container group.
|
|
|
|
Whether the mesh keeps this, drops the per-module layer, containerises the daemons, or writes
|
|
its own supervisor is **open** — costed in research effort 003 and deliberately undecided. It
|
|
no longer gates anything.
|
|
|
|
Two failures worth knowing about, both in the shape of "the change did not apply". A
|
|
per-instance copy of the unit template shadows the template, so edits to the template do
|
|
nothing. And a session-scoped one-shot job loses the environment it was given, because the
|
|
import is one-time and not persisted.
|
|
|
|
## How a node comes into being
|
|
|
|
Three bootstrap scripts, and which one runs depends on the situation:
|
|
|
|
- **First node.** Nothing exists yet, so the script stands up the database the rest of the
|
|
mesh reads from, publishes the catalogue, and starts the mesh. This resolves the
|
|
circularity of a mesh whose source of truth is itself a provisioned module.
|
|
- **Joining.** The node registers, takes its assignment from the database, and syncs.
|
|
- **Rescue.** A node that cannot reach the mesh is brought back far enough to.
|
|
|
|
Bringing a node into being is therefore a **database operation with a script attached**, not a
|
|
checkout. There is no per-node content in the repository to copy.
|
|
|
|
Adoption of a pre-existing machine's configuration was the original path and is now a legacy
|
|
one, explicitly out of scope for the lab
|
|
([`01-to-be/01-end-to-end-testing.md`](../01-to-be/01-end-to-end-testing.md)).
|
|
|
|
## Node identity
|
|
|
|
Each node carries an identity text in its own record, which the daemon writes onto the node at
|
|
startup so that a session on that machine knows which node it is on and how that node
|
|
presents itself. It carries identity only; shared rules live separately.
|
|
|
|
Like everything else derived onto a node, it is generated and not edited there.
|