c9c2dfe6868d8a744dc4c9fe1088be705d60bae8
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Commits
| Author | SHA1 | Message | Date | |
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 jschoubben
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c9c2dfe686 |
011: what a feature is, and what it splits into
The operator wants features gone, and 006 left it open. Measured, and the answer is that nothing replaces them because they were never one concept. A feature is a kind of content a module carries, detected from its directory: twenty-one of them, each with a handler owning six stages — build, publish, install, configure, start, verify. The structural finding: EVERY handler implements EVERY stage. `configs` writes files onto a node, has nothing to build, and has a build stage. `npm` publishes to a registry, has nothing to start, and has a start stage. One interface spans build-time and apply-time, so every kind of content must implement both halves and most do nothing in one — and a stage that does nothing looks exactly like a stage that failed to do anything. They split four ways, across three tiers. Artifacts built once per version and published, where no node is involved — delivery. Resources that are desired state on a machine, which is what ADR 0043 already describes and the host already does — tier 0. Actions run once against something that is not this machine, like a migration against a database on another node — delivery, and seeds go entirely. And checks: the prerequisites are REQUIREMENTS IN DISGUISE, a module saying what must be true before it can be installed, which is what an edge in the graph says; the verifiers are the read-back the host already performs. So `feature` is one word for four things spanning three tiers, which is why the pipeline is hard to reason about. One property must survive the split, and it is the thing the current design got right: content is DETECTED, relationships are DECLARED. A module that says it has migrations and has none is a fault nobody sees until it matters — but what it requires and provides is not visible in a directory and has to be said. |
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jschoubben
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ae099482a9 |
011: twenty cases, and two axes nothing covers
Before settling a schema, what a module can actually be. Twenty kinds of thing, with the hard ones at the end because they are the point. The ordinary nine are unsurprising: a supervised service, a system package with configuration, an application a person launches, a command-line tool, a library that never runs, a one-shot task, a scheduled one, an adapter, and a standalone application whose only difference is where its source lives. The eleven that break a naive schema are where the work is. Something that is a service AND an application — a git forge is consumed as a remote and operated through a web interface, and neither reading is wrong. Something that provides and consumes, because provider and consumer are ends of edges rather than kinds of module. Something the mesh installs that then becomes a node CAPABILITY, which means a node's provides-list is partly derived from what is installed on it and not only detected. Something that must be adopted rather than installed. Something that is a set rather than a thing. Something with exactly one instance for the whole mesh, where assigning it twice is not redundancy but two meshes. Something that is not software at all — a firewall policy, a DNS record, pure desired state, which fits the host's declaration model exactly and an installable package model not at all. An agent. The host itself, which is not a module and needs a schema that can say so. And the things the mesh depends on and does not control, which are why a node can be perfectly configured and still not work. Nine axes come out of it. Two are covered by nothing anyone has proposed: HOW MANY INSTANCES a thing may have, and WHETHER TWO CAN COEXIST — `excludes` covers part of the second and nothing covers the first. And one question the cases sharpen: is "runs" a property or a kind? The axes say property — one schema with a field saying how it runs, `never` included. The alternative is several kinds of module with different schemas, which is the taxonomy this effort already rejected once for services and applications. |
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jschoubben
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f55ecc1a47 |
011: an abstract name needs providers that are actually substitutable
Two corrections from the operator, and the first improves the design rather than narrowing it. `database` is not an edge. The test it fails, and the test the proposal was missing: can a consumer be switched from one provider to another WITHOUT CHANGING? A module speaking Postgres does not speak MongoDB or SQL Server — different wire protocol, dialect, driver — so a consumer declaring `requires: database` and handed any of them breaks. The name promises what no provider can deliver, and the resolver would report a requirement satisfied that is not. `terminal` passes: anything that runs a command in a terminal works and the consumer never learns which it got. So the ADAPTER is what creates an interface. `ai-assistant` is legitimate exactly because adapters normalise what is behind it. Without one there is no interface, there is a category — and a category is a TAG. Tags describe, edges bind, and keeping them apart is what stops the catalogue acquiring a second kind of relationship that looks like a dependency and is not, which is what a folder named after a domain already was. And the domain module goes. A `networking` module gathering a firewall, a resolver and a proxy under one name came from an older shape and does not fit — there is no such thing to install. There is core infrastructure: concrete modules named individually, not flavourable, with no grouping module standing in front of them. Fixed three places where the revision left the old rule standing, including an example manifest still requiring `database` — the kind of contradiction that would have been read as the design rather than as a leftover. |
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jschoubben
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e20a09ae80 |
011: one kind of edge
The design, rather than an account of what exists. A module provides names and requires names, and that single relation absorbs three things this effort had listed separately: requiring another module is requiring a concrete name, requiring a resource is requiring an abstract one, and an interface is simply a name with more than one provider. Nothing has to declare that it is an interface — it either has one provider or several. The move that does the most work: a NODE provides names too. Its profile is a set of them — display-server, container-runtime, an architecture — so a module requiring a display server is satisfied by the node exactly as one requiring a database is satisfied by another module. One resolution instead of two, and a graphical application cannot land on a node without a display server for the same reason, through the same code, that it cannot land without its libraries. Which makes the host's capability detection an input to resolution rather than something a person reads. It was built to be read; it turns out to be a provides-list. `excludes` is the one genuinely new relation, because it is not derivable: two modules that both provide message-bus look interchangeable when installing both would break the machine. Constraints are not placement. They say what must be true of a node, never which node — which is the mistake the measurement found in the current catalogue, where a module pins its database to a named node so a second node cannot provide it without editing the consumer. What it deletes, for the design: the module/resource distinction, the interface as a kind of thing, capability checking as a separate mechanism, domain grouping — folders assert relationships where edges record them, so a domain becomes a query over the graph rather than a directory somebody keeps true — and possibly tiers, if a tier is just a computed level. What it does not delete, stated so it is not discovered later: a resolver still has to exist, with version constraints and conflicts, and the design owes an answer on what it delegates rather than reimplements. |
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jschoubben
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c3a2984b3e |
011: measured, and the premise was wrong — the graph is not missing
The effort was opened to ask whether the catalogue's missing structure is a graph. It is not missing. 126 manifests, 103 edges, no cycles, nothing dangling, deepest chain of five — and a resolver in the SDK that topologically sorts them, already called by the tool loader at startup, the installer when syncing modules onto a node, and the delivery coordinator when expanding what a change affects. It already does something this effort assumed would need designing: a requirement on another module's provision is treated as an implicit edge to the module that provides it. So "ordering by the graph", which ADR 0043 makes the control plane's job, is a thing to call rather than a thing to build. The one place the graph is wrong, it is wrong about the substrate. A module needing a database declares `provider: postgres` inside `provisions:` — which is what a module OFFERS — so the resolver, which reads `dependencies:` and `requires:`, never sees it. Three edges are invisible this way, and they are the mesh's own database, the mesh's own broker, and the work engine's database. The consequence is measurable: computing what a working mesh needs from the declared graph gives registry -> sdk -> mesh -> meshware. Four modules, four levels, no database. Arithmetically correct and obviously wrong, for exactly one reason — a field that means "depends on" is not read as one. That is 04-ISSUES/003 in a new form: not a key nothing reads, but a key read as something other than what it means. Two latent defects, both contrary to ADR 0008 and both in the component ADR 0043 makes responsible for ordering a host will apply without question: a cycle warns and falls back to input order, and a dependency that does not exist warns and continues. Neither has fired, because the catalogue currently has no cycles and nothing dangling, which is why nobody has noticed. And placement is decided in the catalogue: a provision pins itself to a named node in the manifest. Which node runs what is an inventory decision — tier 2 by the skeleton's own test — so a second node cannot provide the mesh's database without editing the module that consumes it. What the graph would DELETE is currently nothing. What it would add is three declarations that no manifest uses today: excludes, a required node capability, and an interface with adapters. Whether they would be used is not measured, and zero usage is equally consistent with nobody needing them and nobody being able to express them. |
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jschoubben
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902739acb6 |
Research 011 — the module graph
The proposal to split modules into provisioning services and applications was worked through and abandoned, for a reason worth keeping: it cannot be filed consistently. A git forge is consumed as a service and operated through a web interface; an analytics service grants tracking identity and is a dashboard. The operator's correction is the sharper form — what runs on the machine is a supervised container, not something a user started. That is a fact about HOW a thing runs, not about what kind of thing it is. So it is a facet, and 0002 survives: everything is a module. What the catalogue is missing is not a taxonomy but a graph. Grouping asserts relationships; a graph records them. Five declarations, of which two exist: requires/provides a resource (yes), requires/excludes another module (no), requires a node capability (no). Plus interface modules that carry no implementation, with adapters providing them. Recorded because it matters: this is a package manager's model, and pacman already has all of it — depends, conflicts, and provides as virtual packages, which is exactly the interface/adapter idea. Arriving there independently is evidence for the shape. It is also a warning about what not to reimplement. Working position on capabilities, to be tested: intrinsic ones (hardware, architecture, network position) are detected and never installed, and a module requiring one it lacks is impossible rather than unresolved. Provided ones (a display server, a container runtime) are not a separate kind of thing — they are modules that provide a capability, so "may the mesh install a capability" is not policy, it is dependency resolution. Issue 007 then bears directly: an installed package is not a capability. Also captured: the operator's assessment that the machinery around a module — scheduled tasks, hooks, migrations, config and env — is worth keeping, seeds are not, and the integration is wrong enough to need a major refactor. Research 005 found supporting evidence from another direction, that the densest apparent coupling in the catalogue is manifest boilerplate churn. The first open question is the one that decides whether this is progress: what does the graph DELETE? If modules gain declarations and lose nothing, it is motion. |