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moellere

print-warden

by moellere
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Python
Remote

print-warden

Print manager for the homelab's 3D printers so a Claude session can hand off everything after design. Slices with a headless OrcaSlicer (Artillery vendor presets + house rules), stages gcode on the printer, starts jobs only with the operator's permission, then watches: deterministic rules over Moonraker telemetry, Obico's spaghetti verdicts via webhook, snapshots from any HTTP camera, timelapse frames per layer, and alerts fanned out through one Home Assistant webhook. Exposes an MCP server (Streamable HTTP at /mcp).

Trust gradient

Action

Who decides

Slice, stage gcode, snapshots, alerts, work light

the warden, automatically

Start a print

the operator: a phone tap (request_start) or quoted chat permission (start_print), and policy.can_start must pass

Pause on detected failure

Obico

Cancel a running print, power off

a human

Printers with a power_device (the X1's Sonoff) are powered on at start and Klipper is coaxed to ready with up to three FIRMWARE_RESTARTs before the print command goes out; the tap still gates the whole sequence.

policy.can_start is plain Python: Moonraker connected, Klipper ready, printer idle, gcode staged, loaded material matches the job. No model is consulted in the gate.

Related MCP server: Klipper MCP Server

Job flow

curl -F file=@part.stl http://nas.local:8710/upload           # or a .scad
submit_job(printer="garagex4", model="part.stl", material="PETG", quality="standard")
   -> slices (tree supports, no brim), uploads gcode to Moonraker as warden/<job>_<name>_<mat>.gcode
job_status(job_id)          # estimates, warnings, can_start + blockers
request_start(job_id)       # phone notification with Start / Skip buttons
start_print(job_id, authorized_by="the operator said: go ahead and print it")   # chat path
list_spools() / set_active_spool("garagex4", 2)   # Spoolman owns spools; the warden records which one is loaded

Qualities: draft (0.24), standard (0.20), strength (0.20), fine (0.12). Materials: PLA, PETG, ABS. overrides on submit_job are OrcaSlicer process keys applied last (e.g. {"enable_support": "0"}).

Run

cp printers.example.yaml printers.yaml   # edit
printf 'HA_BEARER_TOKEN=...\nOBICO_WEBHOOK_SECRET=...\n' > .env
docker compose up -d --build             # Ubuntu 24.04 + OrcaSlicer 2.4.2 AppImage + OpenSCAD
curl localhost:8710/healthz

Obico → Preferences → Notifications → Webhook URL: http://<host>:8710/obico/webhook?secret=<OBICO_WEBHOOK_SECRET>. Phone buttons come back through HA's websocket event bus (mobile_app_notification_action), no HA config needed.

Layout

src/print_warden/
  config.py     YAML -> dataclasses; secrets from env
  moonraker.py  websocket subscriber (read) + upload/start (write, policy-gated)
  rules.py      telemetry rules -> events
  watcher.py    per-printer orchestration, snapshots, light, timelapse, job tracking
  slicer.py     OrcaSlicer CLI wrapper, preset flattening, gcode header parsing, OpenSCAD render
  jobs.py       job ledger (SQLite) with transition log
  policy.py     can_start()
  ha.py         alert webhook, actionable notifications, light control
  ha_events.py  HA websocket: notification button taps
  spoolman.py   Spoolman client (materials, remaining weight)
  server.py     MCP tools + HTTP routes (/upload, /obico/webhook, /ha/action, /files, /healthz)

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