# continuum-proxy

Edge gateway daemon for the Continuum print farm platform. Runs on a Linux
SBC on-site, talks to printers over the LAN, and keeps a connection to the
cloud control plane (`continuum-backend`).

## What's real right now

- **Bambu MQTT** - a real client for both protocol generations (MQTT
  v3.1.1+BambuMQTT v1 on older firmware, MQTT v5+BambuMQTT v2 on current
  firmware), auto-detected per printer on connect (a firmware update can
  move the same physical printer between them, so this isn't something
  config can hard-code once and forget - see `printer/bambu.rs`'s
  `BambuProtocolPreference::Auto`). Request/reply correlation via
  `sequence_id`, an in-memory `print.push_status` cache that merges v1's
  partial updates and replaces on v2's full ones, and TLS trust that
  auto-pins a printer's certificate via trust-on-first-connect the first
  time the bundled CA doesn't verify (`printer/bambu.rs`'s
  `ensure_trusted`) - see `printer/bambu_mqtt.rs`'s doc comment for the
  full protocol write-up.
- **Marlin/RepRap serial** - a real held-open serial connection that paces
  gcode lines by Marlin's own "ok" acknowledgment (`printer/marlin_serial.rs`).
- **Wire shapes from schemas, not hand duplication** - Bambu's raw MQTT
  JSON is built straight from `continuum-schemas`' JSON Schema files via
  `continuum-schema-instance`, instead of a second hand-written copy of
  every request shape drifting out of sync with the schema.
- **Cloud uplink** - a WebSocket client to `continuum-backend` that
  connects, sends a heartbeat on a timer, and reconnects on drop
  (`src/uplink/`).
- **go2rtc watchdog** - restarts the camera-restreaming subprocess if it
  dies (`src/go2rtc.rs`).
- **Bambu file upload** - implicit FTPS (port 990) into the printer's own
  `cache/` directory (`src/printer/bambu_ftps.rs`, via
  `BambuPrinter::upload_file`). **Confirmed live against a P1P on
  2026-10-03**: login, binary mode, and the transfer all work, byte count
  matched exactly.
- **Print status** - `print.push_status` parsed into `PrintReport` with real
  job progress, temperatures, fans and HMS entries. Confirmed live on both
  generations (idle P1P on v1, H2C 20% into a job on v2); regression
  fixtures from those captures are in `tests/fixtures/`.

## Examples worth knowing

- `cargo run --example live_reports [printer-id]` - **read-only**, safe
  against a printer that is mid-print. Connects, reports firmware, and
  watches the status stream. Redirect stderr to capture raw payloads.
- `cargo run --example bambu_idle_checks -- <printer-id>` - **writes**
  (FTPS upload, fan speed). Requires an explicit printer id and refuses to
  run unless that printer reports `gcode_state: "IDLE"`.

## What routes between the cloud and the printers

The uplink and the printer fleet are wired together, in both directions
(`uplink/mod.rs`):

- **Up:** every 5s, one `PrinterTelemetry` snapshot per printer that has
  reported, batched into a single `Telemetry` message. Verified live against
  a P1P and an H2C.
- **Down:** a `Command` from the cloud is looked up by our own printer id,
  executed, and answered with a `CommandResult`. The set of commands is
  deliberately small - a fan speed and a single gcode line - and deliberately
  has no "start a print" variant; see `PrinterCommand`.

One quirk worth knowing: a Bambu on protocol v1 only sends a *complete*
status when asked, so each telemetry tick also fires a `pushing.pushall` for
the next one. A v1 printer's telemetry is therefore one tick behind, which
is why it shows up on the second frame rather than the first.

## What's still a stub

`start_uploaded_file` - the MQTT command that actually *starts* a print from
an uploaded file - is written but has deliberately never been fired, since
that commits a machine to hours of work. Its doc comment lists the three
details to confirm on the first real attempt. `upload_file` is proven, but
only with a small text file, not a multi-megabyte sliced `.3mf`.

PrusaLink (REST) and Klipper/Moonraker (WebSocket) - `printer/prusa.rs`
and `printer/klipper.rs` just `println!` what they'd send. Also not built
yet: local buffering for telemetry across connectivity gaps (so telemetry
produced while the uplink is down is simply lost), LAN printer discovery
(SSDP/mDNS), and the mechanical plate-changer interface.

## Getting started

```bash
cp .env.example .env
cargo run                                  # the daemon: connects every configured printer, then runs the cloud uplink + go2rtc watchdog

cp printers.example.toml printers.toml     # fill in your real printers (gitignored)
cargo run --example auto_connect_bambu     # checks/auto-pins each Bambu printer's certificate, no MQTT needed
cargo run --example test_bambu_certs       # narrower: just the raw TLS handshake, no auto-pinning
cargo run --example printer_polymorphism   # standalone trait+enum demo, fake data, no network/env needed
cargo run --example bambu_commands_demo    # round-trips hand-written structs against real captured Bambu JSON
```

## Structure

```
src/
  main.rs               Loads+connects the printer fleet, then runs the uplink and go2rtc watchdog side by side
  config.rs             Loads settings from environment variables
  fleet.rs              Loads printers.toml into ready-to-use PrinterHandles
  uplink/                WebSocket client to continuum-backend: connect, heartbeat, reconnect on drop
  go2rtc.rs             Restarts the go2rtc camera-restreaming process if it dies
  printer/
    mod.rs               GenericPrinter trait + PrinterBase + PrinterHandle enum - the trait+enum
                         "inheritance" pattern this project uses instead of class inheritance
    bambu.rs             The real Bambu printer type: cert trust, protocol version auto-detect, commands
    bambu_mqtt.rs        The real MQTT wiring underneath bambu.rs - see its doc comment for the protocol details
    bambu_commands/      Hand-written serde structs mirroring continuum-schemas' bambulab/ shapes
    marlin_serial.rs     A real held-open Marlin/RepRap serial connection
    prusa.rs, klipper.rs Still stubs - see "What's still a stub" above
examples/
  auto_connect_bambu.rs   Checks/auto-pins every Bambu printer's certificate (no MQTT)
  test_bambu_certs.rs     Narrower: just a raw TLS handshake per Bambu printer
  printer_polymorphism.rs Standalone trait+enum demo, five fake printers, no network needed
  bambu_commands_demo.rs  Round-trips bambu_commands' structs against real captured Bambu JSON
```

`printers.toml` (gitignored - copy from `printers.example.toml`) holds real
per-printer connection details: host, access code/API key/serial port
depending on vendor, and - for Bambu - an optional per-printer CA
certificate override (see `certs/README.md`; most printers don't need one,
since `connect()` auto-pins automatically).

## Learning Rust through this repo

`src/printer/mod.rs`'s doc comment is where the "how do I do inheritance
without classes" question lives - trait (shared behavior) + struct
(shared fields) + enum (the closed set of concrete types), instead of
`GenericPrinter -> BambuPrinter/PrusaLinkPrinter/...` class inheritance.
Run `printer_polymorphism` to see it work end to end without needing any
real printer on the network.