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Issue 117: a module's own code is a container in one record and a process in another

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Asked what the "sidecar" is and whether a supervised process would do instead. The repository
answers both ways. ADR 0047 (accepted, unsuperseded) says a module with tools or events runs a
container carrying its compiled code. To-be 18 and 20 (both proposed) define a `process` resource
type — the module's own code, a unit the machine's supervisor keeps up — and the worked guide says
plainly "it is why these are `process` rather than four containers." Neither design doc names 0047,
and no decision record mentions a `process` shape at all.

Diagnosed rather than left open, because the ground truth settles what the report could not.
The shape is real: mesh-host defines TypeProcess, applies it, and tests it, and the host's
vocabulary is twelve shapes rather than the nine ADR 0029 counted. So the alternative the report
offered — that two proposed documents describe a type that does not exist — is disproven.

ADR 0029's mechanism is intact and was not enough. The vocabulary-count test names the decision
behind each addition: network 0029, access 0051, opening 0100. The eleventh names a *proposed
design document*, and TypeProcess is the only shape in the vocabulary whose doc comment cites no
ADR. Requiring every addition to name something does not require it to name a decision.

The argument this issue asked for already exists — as a Go test comment. "It is a full-host shape
rather than a portable one: it needs a process supervisor to install into. It does NOT need a
container runtime, which is the point — only software that genuinely needs isolation asks for a
container." That is a decision's context and consequences, in another repository.

What the catalogue does is a third thing: 115 container declarations against 3 process, all three
in showcase — the module to-be 20 documents. There the tools resource is a container running
`sleep infinity` on a bare upstream base with the broker credential mounted, and the tools and
provisioner entrypoints are run by nothing. That is the condition 0047 was written to end, back
in a new shape.

Where the isolation argument leaks is narrower than expected and worth having precisely: the
serving key and the credential shape both conform. But serveTools serves every registered module
over one broker connection, the runtime takes its modules from a comma-separated list, and
x-source is stamped from the single credential — so two modules in one runtime means the second's
events are attributed to the first. Nothing refuses it and no test asserts against it.

Located on hq rather than on a code repository: the implementation and the design layer agree,
and the missing thing is the record. Which shape is right is left open, deliberately — this
establishes that the question was answered in practice and never written down, not which answer
is correct.

One correction kept in the trail: the first search here was for len(Vocabulary()), found nothing,
and was two steps from being written up as "the mechanism ADR 0029 relied on is gone." The test
binds the slice to a local first. A negative search result read as a fact about the world is the
same error issue 113 recorded.
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---
status: located
opened: 2026-09-25
located-in: [hq, mesh-catalog modules/showcase, mesh-sdk src/tools/index.ts, mesh-tools]
fixed-by:
amended-design:
---
# 117 — A module's own code is a container in one record and a process in another
## What was observed
Asked what the "sidecar" is — the second container a code-carrying module runs beside its
service — and whether a supervised process would do instead. Reading the records to answer it,
the repository answers both ways, and nothing reconciles them.
| record | status | what runs a module's own code |
|---|---|---|
| [ADR 0047](../../02-DECISIONS/0047-a-module-runs-its-code-as-its-own-process-with-its-own-account.md) | **accepted**, 2026-09-04 | "a **container**, the tool runtime carrying that module's compiled code" — one module, one process, one account; events and tools in that same process, "not a second one to scope and seal" |
| [`01-to-be/18-building-a-module.md`](../../03-DESIGN/01-to-be/18-building-a-module.md) | proposed, 2026-09-21 | a resource type table in which `container` is "an image" and **`process`** is "**its own code**, in three modes", whose default mode is "a unit restarted when it exits", supervised by the machine |
| [`01-to-be/20-writing-a-module.md`](../../03-DESIGN/01-to-be/20-writing-a-module.md) | proposed, 2026-09-21 | one module declaring **four** `process` resources — events, tools, provisioner, a scheduled ingest — each with its own `run` argv, and the sentence "it is why these are `process` rather than four containers" |
Three disagreements, not one:
1. **Container or unit.** ADR 0047 chose a container and said why: a node-wide runtime loading
every module's code could not hold a per-module account, so the runtime is per-module. The
design docs choose a supervised unit running an argv and give no reason, because they do not
record that they are choosing.
2. **One process or several.** ADR 0047's "one module, one process, one account" is the whole
content of its second and third sections. The worked guide declares four for one module and
presents four as the point.
3. **Whether the record was consulted at all.** Neither design doc names ADR 0047 in
`decisions:`. No record supersedes or extends it on this. **The string `process` as a resource
type appears in no decision record** — the shape exists only in two `proposed` design docs.
Meanwhile the thing as built is the container. [ADR 0029](../../02-DECISIONS/0029-a-network-is-a-shape-because-an-action-cannot-be-undone.md)
records that "anything that is a service plus a sidecar currently has to publish a port to talk
to itself," which is one of the things the host's `network` shape was added for.
[Issue 113's diagnosis](../113-the-object-stores-images-were-withdrawn-upstream/01-diagnosis.md)
found a catalogue module declaring "two container resources," the second a runtime sidecar
"pinned at an all-zeros digest, meaning nothing was ever published for it."
[Issue 095](../095-a-module-assigned-after-genesis-has-no-broker-account/00-report.md) is a
sidecar crash-looping on a credential while its service served correctly.
[ADR 0093](../../02-DECISIONS/0093-a-fixture-that-runs-a-modules-runtime-carries-its-name.md)
records that a bed wanting "a sidecar without its server raises the server."
### And the word is in no glossary
"Sidecar" appears sixteen times across five records — two decisions and three issues. It is
absent from [`00-META/glossary.md`](../../00-META/glossary.md), and absent from every document
under [`03-DESIGN/`](../../03-DESIGN/), in both layers. ADR 0047, which creates the thing, never
uses the word; it says "runtime process" and "runtime container". The glossary's own rule is that
"a new name for an existing thing lands here first, in the same change that introduces it in
code," and the page exists because "the terms kept drifting in conversation." A reader asking
what the sidecar is has nowhere in the design layer to look, which is how this was found.
## Why it matters beyond this instance
- **A module author reading the current guide writes a `process`; the catalogue as built declares
a `container`.** [`20-writing-a-module.md`](../../03-DESIGN/01-to-be/20-writing-a-module.md) is
a worked guide with a manifest in it. Whichever of the two is wrong, somebody follows it.
- **The cost of the container shape is paid in four places and totalled in none.** A published
image per code-carrying module, a network so a module can reach itself, a bed that cannot run a
runtime without raising the server it manages, and a credential failure that presents as the
module's own bug. Each record argues its own piece is worth paying. No record puts them beside
the alternative.
- **Both shapes carry a cost the other does not, and neither is written down.** A container
carries its own interpreter; a `process` declaring `run: ["node", "index.js"]` needs an
interpreter present on the machine, which is the machine dependency the statically linked host
([ADR 0005](../../02-DECISIONS/0005-the-node-host.md)) exists to avoid. And `run` is an argv,
where [ADR 0005](../../02-DECISIONS/0005-the-node-host.md) refuses `action` because the link may
not carry a command — a refusal [`18-building-a-module.md`](../../03-DESIGN/01-to-be/18-building-a-module.md)
restates on the same page that it introduces `process`.
- **This is the repository's own named failure mode, in its own records.** `cycle.py` enforces
that a to-be doc names *at least one* decision. Both docs do, so both pass, while introducing a
resource type no decision records and contradicting an accepted one. The rule is "no design
without a decision"; the check is "no design without *a* decision." An unenforced rule is
indistinguishable from a wrong one, and these two documents are what that gap looks like when
something walks through it.
## Open questions
- Which is the decision — container or supervised unit? If the design docs are right, ADR 0047
needs superseding rather than quietly outliving. If ADR 0047 is right, two proposed documents
and a worked manifest describe a resource type that does not exist.
- Is one account per module satisfied by a per-module *unit* as well as a per-module *container*?
ADR 0047's argument rules out a node-wide runtime sharing one account. It does not appear to
rule out a unit holding one scoped credential, and nothing has said so either way.
- If several processes for one module are right, what holds the accounts? ADR 0047 refused "a
second one to scope and seal" for events beside tools. Four processes are four somethings.
- How does a `process` get its interpreter, and does declaring one reintroduce the machine
dependency the host is built to avoid?
- Is `run` an argv the link may carry, given `action` is refused for being one? If the answer is
that a `process` reconciles and an `action` does not, that distinction is not written down.
- What is the thing called, and where does the design layer describe it? Whichever shape wins, no
document in either layer currently says a code-carrying module runs a second thing beside its
service.
- **How would this have been caught?** A decision and a design doc disagreeing on a resource type
is mechanically checkable: the resource types a design doc names are a closed set, and every
member of it either appears in a decision or does not. Whether that check is worth writing is
part of this issue, not settled by it.
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# Diagnosis — 117
## Which trees were searched, 2026-09-25
Named first, because [issue 113](../113-the-object-stores-images-were-withdrawn-upstream/01-diagnosis.md)
is the record of reporting absence in one repository as absence in the mesh.
| Searched | At |
|---|---|
| `mesh-host`, `mesh-catalog`, `mesh-tools`, `mesh-sdk`, `mesh-controller` | `main`, fresh shallow clones |
| `hq` | `main`, and the two branches named under finding 7 |
**Not searched:** the private migration repository; the open pull requests on the catalogue and
the controller; any branch of a code repository other than `main`. A statement below about "the
catalogue" is a statement about its `main`.
## The report's central question is answered: the shape exists
`mesh-host` `internal/declaration/declaration.go` defines `TypeProcess Type = "process"`.
`internal/apply/process.go` applies it — it writes the unit, writes the timer for a scheduled one,
and gates what follows a run-once one. It has tests of its own in both packages. The resource
carries a bundle `source` with a `digest`, a `run` argv, `env` and `env-file`, a `user`,
`restart-on`, and the `run-once` and `schedule` modifiers.
So the report's alternative — "if ADR 0047 is right, two proposed documents and a worked manifest
describe a resource type that does not exist" — is **disproven**. It exists, it is implemented, it
is tested, and the host's vocabulary is now **twelve** shapes rather than the nine
[ADR 0029](../../02-DECISIONS/0029-a-network-is-a-shape-because-an-action-cannot-be-undone.md)
counted.
## The enforcement ADR 0029 asked for is intact, and it recorded this gap rather than closing it
ADR 0029 said "the vocabulary is nine, and the count moves with a record. The test that asserts it
names this one." That test exists — `internal/declaration/declaration_test.go` asserts the count is
twelve and fails with the reason rather than a number. Above the assertion, a paragraph per
addition names what made it one:
| shape | the test names |
|---|---|
| `network`, ninth | ADR 0029 |
| `access`, tenth | ADR 0051 |
| **the eleventh** | **`03-DESIGN/01-to-be/18-building-a-module.md`** — a design document, `status: proposed` |
| `opening`, twelfth | ADR 0100 |
The eleventh is this one. The test still calls it `daemon`, the code calls it `TypeProcess`, and
its paragraph is the only one that names a design document where the others name a decision.
Independently: in `declaration.go`, `TypeProcess` is the **only** shape in the vocabulary whose doc
comment cites no ADR — `network` cites 0029, `access` 0051, `opening` 0100, `user` and the refusal
of `action` cite 0005.
**So ADR 0029's mechanism worked exactly as designed and was not enough.** It requires every
addition to name something. It does not require that something to be a decision, and the one
addition that named a proposed design document instead is the one this issue is about.
### A correction to this trail, recorded because it was one grep from being a finding
The first search here was for `len(Vocabulary())` and found nothing, and the working conclusion for
two steps was that no count assertion existed any more — which would have been written up as "the
mechanism ADR 0029 relied on is gone." It is not gone. The test binds the slice to a local variable
first, so the assertion reads `len(speaks) != 12`. The claim was wrong, it was caught by reading the
file rather than by grepping it, and the shape of the error is the same one issue 113 recorded: a
negative search result read as a fact about the world.
## The argument the report asked for already exists, in a test comment
The report asked why a container rather than a supervised process, and said the reasoning was not
written down. It is — in `declaration_test.go`, as the eleventh shape's paragraph:
> Running code of one's own meant a `container` and therefore an image; running a script meant a
> `service` and a unit somebody else had to install. One intent — run this and keep it running —
> expressed two unrelated ways, with the hosting chosen before anything could be declared. […] It
> is a full-host shape rather than a portable one: it needs a process supervisor to install into.
> It does NOT need a container runtime, which is the point — only software that genuinely needs
> isolation asks for a container.
That is a decision's Context and Consequences, in a Go comment, in another repository. Nothing in
`02-DECISIONS/` contains it. `TypeProcess`'s own doc comment adds the rest — that three modes beat
three kinds, and that a first draft added a `daemon` for the long-running case alone.
## The catalogue is containers, and the one exception is the reference module
71 modules on `main`. Counting the `type` of every declared resource:
| `container` | `process` |
|---|---|
| 115 | **3** |
All three `process` resources are in **one** module: `showcase` — the module
[`20-writing-a-module.md`](../../03-DESIGN/01-to-be/20-writing-a-module.md) is a worked guide for.
### And in that module, the tools do not run
`showcase` declares its migrate, server and reporting steps as `process`. Its fourth resource, the
one for tools, is a **`container`** — and its image is the module's `helper` artifact, which the
same manifest declares as `kind: upstream` from a bare distribution base. Its command is
`sleep infinity`. It mounts the broker credential and sets the variable naming it, and runs nothing.
Meanwhile the module's `code` bundle declares six entrypoints. Three are run by the three `process`
resources. The tools entrypoint and the provisioner entrypoint are **run by no resource in the
manifest.**
Two consequences worth stating separately:
- **The worked guide does not match the module it documents.** The guide shows four `process`
resources, the fourth being `{"id": "tools", "type": "process"}`. The module has three and a
container.
- **This is the condition ADR 0047 was written to end, in a new shape.** That record's Context says
the conversion "produced tools and events that, as it stands, never execute," and its first
Consequence is that they become runnable. In the reference module they do not execute again —
not for want of a runtime this time, but because nothing declares one that runs them.
## The harness has no per-module boundary, and nothing refuses a second module
This is where ADR 0047's isolation argument is load-bearing, so it was checked rather than assumed.
- `mesh-sdk` `src/tools/index.ts`: `serveTools` iterates `collectTools()` over a module-level
registration array and serves **every registered module's** tools over the **one** `broker` it
was handed.
- `mesh-tools` `src/main.ts`: the modules to load come from one variable as a **comma-separated
list**, and the runtime sets its module and node identity from the **single** credential.
- `mesh-sdk` `src/events/index.ts`: an emitted event's `x-source` is stamped from that single
module identity.
Put together: load two modules into one runtime and everything the second emits is attributed to
the first, because there is one credential and the identity comes from it. That is precisely the
failure ADR 0047 predicted — "able to emit as any of them" — reached by a different route, since
the credential is correct and there is only one of it for two modules. **Nothing in either
repository refuses the second module**, and no test asserts that a runtime serves one.
### Ruled out, in fairness to the implementation
- **The serving key conforms.** ADR 0047 replaced a single `tools.invoke` dispatch with a per-tool
key, and the SDK does that: a tool is served on `<module>.<tool>` with the account scoped
`serve.<module>.*`. The superseded `tools.invoke` survives only in **prose** — the doc comment
directly above the conforming code, and the `mesh-tools` README, which also describes the runtime
as per-node. The code is ahead of its own documentation.
- **The credential shape conforms.** The sealed per-module credential file is preferred in code, and
the plain URL is documented as the bootstrap case before a module has an account — not the
ordinary path.
So the account is the right shape and the key is the right shape. It is the **process boundary**
that is declared nowhere and enforced by nothing.
## An unmerged report already asks the narrow version of this
Branch `issue/113-controller-container-or-process`, one commit, 2026-09-24, adds a report titled
**"Should the controller run as a container, or as a process the host supervises directly?"** with
`located-in: [mesh-controller module.json, mesh-host internal/apply]`. Its observation is that the
controller is declared a `container` with `network: host` — so container network isolation, the
property that resource type usually buys, is not in use — and it asks what `type: container` buys
that `type: process` would not.
It is unmerged and numbered 113, which is taken. A sibling branch,
`issue/113-record-the-repin-and-fold-114`, is why `114` is free.
**That report and this one are the instance and the general condition**, and they do not conflict:
it asks about one module that is not a code-carrying sidecar at all, and reaches the same question
from the opposite end.
## What is located, and what is not
**Located — and it is not a code defect.** The implementation and the design layer agree with each
other; the **decision record is what is missing**, and the accepted record that occupies its place
says the other thing. ADR 0047 is `accepted`, cited by the module protocol, and unsuperseded, while
the host it describes has had a purpose-built shape for a module's own code since the eleventh
vocabulary entry.
| Owner | What is theirs |
|---|---|
| `hq` | the missing record for the `process` shape; ADR 0047 left standing; the worked guide that does not match the module |
| `mesh-catalog modules/showcase` | tools and provisioner entrypoints that no resource runs; a tools container that sleeps |
| `mesh-sdk src/tools/index.ts` | several modules served over one credential, unrefused and untested; a doc comment describing a superseded dispatch |
| `mesh-tools` | a README describing a per-node multi-module runtime the code no longer prefers |
**Not located, and deliberately open:** whether `process` or `container` is *right* for a module's
own code. This diagnosis establishes that the question was answered in practice and never recorded
— not which answer is correct. The arguments on both sides now exist in writing; they exist in a
test comment and a proposed design document, and one of them contradicts an accepted decision.
## What would close it
1. A decision record for the `process` shape, carrying the argument currently in
`declaration_test.go`, and saying what becomes of ADR 0047 — superseded in whole, or in the part
that names a container.
2. `18-building-a-module.md` and `20-writing-a-module.md` naming that record in `decisions:`, and
the worked manifest agreeing with the module.
3. The eleventh shape's paragraph in the vocabulary test naming a decision, like the other three.
4. **How the rule is checked, since a rule states how it is checked:** every shape in the host's
vocabulary names a decision, asserted where the count is already asserted — which turns "no
design without a decision" into something stronger than "no design without *a* decision" for
the one vocabulary where each entry is a security decision.
5. Whether a runtime may serve more than one module answered either way, and asserted — a refusal
if not, a test that two modules' events keep their own source if so.