continuum-schemas/schemas/bambulab/README.md

# bambulab/ JSON Schemas

Documentation/validation schemas for Bambu's raw MQTT wire format, mirroring
continuum-proxy's `src/printer/bambu_commands/` — not used for codegen (the
Rust structs there are hand-written; see that module's doc comment for why),
but genuinely useful on their own: language-agnostic documentation of the
wire format, and usable to validate a captured MQTT payload without writing
any Rust to do it.

## Layout

```
bambulab/
  envelope.schema.json     the base — sequence_id + command, shared by
                            every command in every generation, so it lives
                            here unversioned, not duplicated under v1/v2
  v1/
    request.schema.json     BambuRequest dispatcher — one key per category
                            ("info", "pushing", ...), each a oneOf (a
                            category can have more than one request shape)
    report.schema.json      BambuReport dispatcher, same idea
    request/
      info/
        get_version.schema.json
      pushing/
        pushall.schema.json
    report/
      info/
        get_version.schema.json
        module_info.schema.json
      print/
        print.schema.json    the ongoing print-state push
        ams.schema.json
        ams_unit.schema.json
        ams_tray.schema.json
        xcam.schema.json
  v2/                       add the same split once V2's wire format is
                            known to differ from V1's — removed for now
                            rather than leave broken copy-pasted stubs
```

**One real correction baked into this layout**: the report category for
whatever a `pushall` request triggers is `report/print/`, not
`report/pushing/`. Sending `pushall` (which *does* go to the `pushing` key
on the request side) makes the printer start/refresh an ongoing state-push
stream, and that stream arrives under the `print` key — a different root
key from the request that triggered it. A category folder here means
"what root key does this arrive under", not "what request caused it" — the
first version of this schema got that wrong (see git history) before a
closer read of the real capture caught it.

## The "inheritance" pattern

Every command/response schema *extends* `envelope.schema.json` with
`allOf` + `$ref`:

```json
{
  "allOf": [
    { "$ref": "../../../envelope.schema.json" },
    { "type": "object", "properties": { "command": { "const": "get_version" } } }
  ]
}
```

This is genuinely closer to real inheritance than anything else in this
project's schema stack (proto, Rust): the instance must satisfy the base
schema *and* the extension schema simultaneously, and — verified with
negative test cases, not just asserted — `envelope.schema.json`'s
`required: ["sequence_id", "command"]` is actually enforced on every
schema that extends it, not just copy-pasted as documentation.

`v1/report/print/ams_tray.schema.json` is the other JSON-Schema-specific
tool worth knowing: `oneOf`, for "this is exactly one of several
genuinely different shapes" (an AMS tray slot is either empty — just
`id` — or loaded — the full field set — never something in between).
`oneOf` requires exactly one branch to match; watch out for a base-style
branch (like `EmptyTray`) accidentally also matching a more specific
branch's instance if the specific branch doesn't require enough fields —
verified and fixed once already here, see that file's description.

**One gotcha if you add a new base-style schema**: don't set
`"additionalProperties": false` on something meant to be `allOf`-extended.
`allOf` validates every sub-schema against the *whole* instance
independently — it doesn't merge object schemas — so a closed base schema
would reject every field the extending schema adds. Leave
`additionalProperties` unset (defaults to allowed) on anything used as a
base; enforce closedness only on the top-level dispatcher schemas
(`v1/request.schema.json`/`v1/report.schema.json` do this correctly —
check their `additionalProperties: false`).

## `$id` convention

Every schema's `$id` is its real Gitea raw-file URL:
`https://git.octoturge.com/Continuum/continuum-schemas/raw/branch/main/schemas/bambulab/...`
— a genuinely dereferenceable URI (verified: `raw/branch/main/<path>` is
the correct Gitea pattern, not `raw/<path>` or `raw/<branch>/<path>`),
rather than a made-up placeholder domain. `$ref`s between files stay
relative paths; `$id` is what a validator uses as the base URI to resolve
those relative refs, and it's also what lets a schema be fetched
standalone by anything that wants to dereference it directly.

## Validating something

`$ref` resolution here relies on each schema's `$id` as the base URI for
its own relative refs (standard JSON Schema behavior) — register schemas
by `$id`, not by filename, or you'll hit collisions (`get_version.schema.json`
exists under both `request/info/` and `report/info/`):

```python
from referencing import Registry, Resource
from jsonschema import Draft202012Validator
import json, glob

resources = [
    (json.load(open(p))["$id"], Resource.from_contents(json.load(open(p))))
    for p in glob.glob("**/*.schema.json", recursive=True)
]
registry = Registry().with_resources(resources)

schema = json.load(open("v1/request.schema.json"))
Draft202012Validator(schema, registry=registry).validate(
    {"info": {"sequence_id": "0", "command": "get_version"}}
)
```