fabrication-prep

Boundary: this repository is MADFAM's public fabrication-prep service (slicing and printer, filament and process profiles). It holds no secrets, hostnames of internal nodes, or private runbooks. Identity is Janua, orchestration is pravara-mes; this service never moves a machine.

fabrication-prep turns a generator render bundle (GOC-1: geometry plus variables.json) into printer-ready output with the OrcaSlicer command line and versioned, digest-pinned printer, filament and process profiles:

Target	Printer class	Output	Media type
klipper_gcode	Klipper (Moonraker), e.g. Voron 2.4 class CoreXY	plain G-code plate_1.gcode	text/x-gcode
bambu_3mf	Bambu Lab A1 class (LAN mode)	sliced 3MF plate_1.gcode.3mf	model/3mf

Every job also produces slicer-variables.json: the input and GOC-1 instance digests, the profile digests, the overrides, the effective process values as OrcaSlicer reported them, the OrcaSlicer version, the output digest, the slicer's estimates (print time, filament) and its warnings. pravara-mes records these in the product passport (MES-1 §7).

Status: v1, in development, not deployed. Licence: AGPL-3.0-only (see LICENSE).

Where it sits

yantra4d (render bundle: STL/3MF + variables.json)
      │  HTTPS, allow-listed hosts, sha256-verified
      ▼
pravara-mes dispatcher ──POST /v1/slice-jobs──▶ fabrication-prep API ──▶ Postgres queue ──▶ worker (OrcaSlicer CLI)
      ▲                                                                                        │
      └──GET /v1/slice-jobs/{id}: status + signed URLs (output, slicer-variables.json) ◀───────┘
pravara edge node: downloads the signed URL, verifies the sha256, uploads to the printer (MES-1 §2).

Separation of concerns: Janua issues identity; pravara-mes orchestrates and dispatches; yantra4d generates geometry; this service only slices. It never contacts a printer.

API (/v1, OpenAPI at /openapi.json)

Method + path	Auth	Result
POST /v1/slice-jobs	Janua token, scope fabrication-prep:slice	202 + job (Location header); Idempotency-Key replay 200; reuse with another body 409; invalid 422
GET /v1/slice-jobs/{id}	same, owner only (404 for others)	status, attempts, error, and when succeeded output + slicer_variables with fresh signed URLs and estimates
GET /v1/profiles	same	the profile catalog (ids, versions, digests, compatibility)
GET /v1/profiles/{kind}/{id}/{version}	same	one profile's OrcaSlicer JSON
GET /v1/artifacts/{sha256}?exp&kid&sig	signed URL only	the bytes; 403 when the signature is missing, wrong, expired or for another artifact
GET /health, GET /ready	none	liveness; readiness = DB round trip at the expected schema revision

Request body (MES-1 §4):

{
  "input": {"url": "https://<render host>/…/part.stl", "sha256": "<64 hex>", "media_type": "model/stl",
            "variables": {"url": "https://<render host>/…/part.stl.variables.json", "sha256": "<64 hex>"}},
  "printer_profile": "klipper-corexy-350-0.4",
  "process_profile": "standard-0.20-klipper",
  "filament_profile": "petg-generic-klipper@1",
  "overrides": {"wall_loops": 4, "sparse_infill_density": 40},
  "requirements": {"process": ["fff"], "materials": {"any_of": ["petg", "pla"]},
                   "process_parameters": {"wall_loops": {"min": 3}, "sparse_infill_density": {"min": 30, "unit": "percent"}}},
  "part": "corner_3way",
  "target": "klipper_gcode"
}

• input.variables (optional) is the GOC-1 sidecar. When given, the worker verifies its digests (GOC-1 §3.2, §3.4) and that it lists the input's sha256, and copies instance_id/variables_sha256 into slicer-variables.json.
• Profile references are id (newest version) or id@version; the job records the resolved version and digest.
• overrides keys must be process-parameters vocabulary keys whose OrcaSlicer preset is print or filament. Printer keys (nozzle_diameter) and the bed_temperature placeholder are refused: choose another printer profile, or override the active plate's key.
• requirements is a RequirementProfile (min/max inclusive, or value), with optional parts.<part> layered over the top level for the named part. A violation is a 422 naming the key, the range and the value: {"code": "override_out_of_range", "path": "/overrides/wall_loops", "details": {"key": "wall_loops", "value": 2, "min": 3, "unit": "count", "source": "override"}}. Profile values are checked before slicing; after slicing the worker re-checks against OrcaSlicer's own record of the values it used and fails the job (requirements_not_met) if any is out of range.

Job states: queued → running → succeeded | failed (permanent: digest mismatch, slicer refused the input, requirements not met) | dead_lettered (transient failures exhausted JOB_MAX_ATTEMPTS). Terminal transitions emit outbox events slice_job.succeeded|failed|dead_lettered.

Slicing — what is proven

Measured with the official OrcaSlicer 2.4.2 macOS universal release on 2026-10-03, slicing a real yantra4d render (tslot-corner corner_3way, GOC-1 complete: true) through the full API → queue → worker path:

• --slice 0 --outputdir D writes plain G-code to D/plate_1.gcode. That is the Klipper output; no 3MF step.
• --export-3mf NAME writes a sliced 3MF, and NAME is resolved relative to --outputdir. Its Metadata/plate_1.gcode, plate_1.gcode.md5 and slice_info.config (prediction s, weight g) are checked before the 3MF is accepted. That is the Bambu output.
• Loose profile files must be flattened: the CLI does not resolve inherits for them, and the process must name the printer in compatible_printers with the printer's from set to system. The shipped profiles do both.
• The CLI defaults the plate to Cool Plate; the printer profiles pin curr_bed_type.
• Headless runs skip thumbnails (no OpenGL); slicing is unaffected.
• The Linux image runs fabrication-prep selftest-slice for both targets in CI. The Linux path is proven only by that job: images were not built on the development host.

Not proven yet: printing either output on physical hardware (the edge bridge lane, MES-1 §2). The Bambu 3MF's printer_model_id metadata is empty, because the 2.4.2 CLI looks for profiles/BBL/machine_full/, which the release does not ship. Whether the A1 firmware accepts that file is unverified.

Profiles

fabrication_prep/profiles/: 12 flattened OrcaSlicer JSON profiles, catalog.json (ids, versions, sha256 of the canonical JSON, compatibility, base chain with git blob ids verified against the v2.4.2 tag) and provenance/<ref>.json (the OrcaSlicer file behind every value, or the MADFAM authoring group and its reason). Rebuild: python scripts/build_profiles.py --orca-profiles <OrcaSlicer resources/profiles> --tree-json <tree>. Profiles are immutable: a change is a new version. The worker refuses to start when the installed CLI is not the version the profiles are pinned to.

Profile	Base (OrcaSlicer 2.4.2 system profile)	MADFAM-authored values
printer klipper-corexy-350-0.4@1	Voron / Voron 2.4 350 0.4 nozzle	curr_bed_type = Textured PEI Plate
printer bambu-a1-0.4@1	BBL / Bambu Lab A1 0.4 nozzle	curr_bed_type = Textured PEI Plate (Orca's own A1 default_bed_type)
filament pla-generic-klipper@1 / petg-generic-klipper@1	OrcaFilamentLibrary / Generic PLA @System, Generic PETG @System	none
filament tpu-95a-klipper@1	OrcaFilamentLibrary / Bambu TPU 95A @System	none
filament pla-generic-bambu-a1@1 / petg-generic-bambu-a1@1	BBL / Generic PLA @BBL A1, Generic PETG @BBL A1	none
filament tpu-95a-bambu-a1@1	BBL / Bambu TPU 95A @BBL A1	none
process standard-0.20-klipper@1	Voron / 0.20mm Standard @Voron	none
process standard-0.20-bambu-a1@1	BBL / 0.20mm Standard @BBL A1	none
process tpu-safe-0.20-klipper@1, tpu-safe-0.20-bambu-a1@1	the standard process of that printer	16 speed/acceleration values (below), not yet validated on a printer

For every profile, the name, from and compatibility keys are rewritten so that our ids appear in the G-code (printer_settings_id = klipper-corexy-350-0.4@1). TPU 95A filaments require a tpu-safe process.

TPU-safe values (mm/s, mm/s²): outer_wall_speed 25, inner_wall_speed 30, sparse_infill_speed 30, internal_solid_infill_speed 30, top_surface_speed 25, gap_infill_speed 25, initial_layer_speed 15, initial_layer_infill_speed 20, bridge_speed 20, support_speed 30, support_interface_speed 20, default_acceleration 2000, outer_wall_acceleration 1000, inner_wall_acceleration 2000, top_surface_acceleration 1000, travel_acceleration 3000. Reason: MADFAM authoring, not an OrcaSlicer value. The TPU 95A filament profiles cap volumetric flow at 3.2-3.6 mm3/s; at 0.2 mm layers and ~0.45 mm lines that is ~35-40 mm/s. Line speeds are set below that so the cap never silently rescales them, and accelerations are reduced for a soft filament in a direct-drive extruder. Not yet validated on a physical printer.

Run locally

python3.13 -m venv .venv && . .venv/bin/activate && pip install -e '.[dev]'
# throwaway Postgres (TCP only), then the roles:
psql -h 127.0.0.1 -p <port> -U postgres -f scripts/test-db-setup.sql
export FABRICATION_PREP_TEST_ADMIN_URL=postgresql://fabrication_prep_owner@127.0.0.1:<port>/fabrication_prep_test
export FABRICATION_PREP_TEST_APP_URL=postgresql://fabrication_prep_app@127.0.0.1:<port>/fabrication_prep_test
pytest -m "not orcaslicer" --cov=fabrication_prep          # what CI runs
ORCASLICER_BIN=<path to the CLI> ORCA_PROOF_BUNDLE_DIR=<dir with part.stl + part.stl.variables.json> \
  pytest -m orcaslicer                                      # the real-slicer proof
fabrication-prep selftest-slice --target bambu_3mf --bin <path to the CLI> --workdir /tmp/st

Configuration is environment-only (fabrication_prep/settings.py documents each key and where it comes from).

Documents

• AGENTS.md — rules for agents and contributors working in this repository.
• docs/operator-setup.md — the owner's steps: push, Janua client, one enclii onboard (database, runtime role and generated keys), enclii buckets create, deploy wiring, smoke. No step handles a credential.
• fabrication_prep/schemas/slicer-variables.schema.json — the output document's JSON Schema.
• MES-1 contract (MADFAM internal) §4 — this service's contract.