Scenario Maya Pipeline Scripting

Maya pipeline scripting (pipeline TD)

Expert pipeline work is contracts plus proof: every file that leaves Maya goes through generated names, explicit export settings and a re-import check, and no batch trusts one Maya process with two hundred files. The pipeline TD never types what can be generated, never trusts a default, and verifies by reading the output back. If a sibling skill named here is missing from your available skills, ask the user to install it (npx skills add scenario-labs/skills --skill <name>); unattended, proceed from tool schemas and flag the gap.

REQUIRED BACKGROUND: scenario-maya-expert (execution channel, review loop, 2027 version traps).

Status (2026-09-24): every Maya call here is not yet run in Maya (not installed). scripts/mx_pipeline.py ran offline, its Maya layer against fakes. First action once Maya is installed: tests/code/maya-pipeline-scripting/run_all.sh.

Stance (the expert delta)

• Never type what can be generated (Guignolle, Borderlands, lfWkJrkhd2U [00:04:58]): names, namespaces, paths and clip ranges come from a manifest; validation sits at the point of action (approved-shot warning, scene breakdown, publish diff green, blue, red [00:22:11] to [00:24:57]).
• Prove it by reading the output back (dcc-mcp's numbers-over-claims standard; the Maya Help's test: the FBX reimports with identical normals, scale, axis and length): re-import in a clean scene and compare meshes, triangles, joints, per-mesh bounds, normal directions, units and up axis; read takes with FBXRead; reopen USD with pxr; hash sources. One mayapy per file: FBX settings and optionVars survive file(new=True).
• Never run blind (chadrik, maya-mcp-server: without stdout and stderr "the agent is blind"; FBX doc: in batch the log is the only feedback on problem files): keep FBXExportGenerateLog on and read each child's log; children run with MAYA_DISABLE_ADP=1 and Maya's stderr at warning (maya_log="all" to debug); read stdout, stderr and maya_messages after every bridge call.
• FBX is global state (Maya 2027 Help, FBX MEL commands): push, reset, set every option, clear the take accumulator, query back and log next to the file, pop. Bake Start and End are never stored in presets. Tangents only export on all-triangle meshes; non-orthogonal matrices are dropped. Triangulate in Maya with controlled edges (Epic).
• Export defaults are traps (maya-usd readme): frameRange [1, 1], defaultMeshScheme catmullClark (no normals), skeletons off, namespaces kept. Pass every flag, then reopen with pxr.
• At scale, structure beats hardware (Markowski and Hübschmann, RISE, 8UIW-g1_heg): value clips instead of full-range caches [00:37:03]; mute your own layer and every stronger one [00:26:19]; pin versions, record them in assetInfo [00:23:01].
• Reference edits replay by name and DAG path (Maya 2027 Help): never rename or restructure a published child file; check reference health (unloaded, missing, failed edits) before any fix, and after every version swap. Shots reference assets; engines get baked exports.
• Profile before optimizing, correct before fast (Roselle, rhtERzmAoUM [00:04:14]; Using Parallel Maya 2027): DG, Serial and Parallel must agree first; headless numbers measure evaluation, not drawing. Python builds and exports; native nodes evaluate (Fragapane, _0mb4wIZi80 [00:55:10]).

Establish first

Workflow

1. Preflight, inventory, fixtures. P.preflight(out, scenes): mayapy, localhost and host name resolution (macOS batch renders hang on it), disk, readable scenes. P.find_scenes(root). One tiny scene per rule, each breaking one thing (test_engine_checks.py); the full chain on 5 real files. GATE: preflight ok; every fixture caught; time per file known.
2. Batch. P.batch(scenes, job, out, plugins=("fbx",), timeout=900): one mx_run child per scene, script nodes off, MX_PIPELINE_OUT/STEM/SOURCE and a per-child FBX log name in the env. Jobs return status, issues, fixes, exports (procedures.md P1). isolation="session" only for many small trusted files; crashed ones re-run isolated. GATE: one report per scene, summary["sources_untouched"] True, every non-pass record explained.
3. Validate, read-only. Reference health first: P.reference_issues(P.references_report()) (R01 unloaded, R02 missing, R03 failed edits, R04 foster parents). Then mx_validate.validate(profile, roots) and P.check_engine_export(roots, engine, kind, rules={"fps": 30}) (E01 to E27: units, one root, names, namespaces, matrices, triangulation, UV and color sets, locked normals, influences, collision, pivot, joints, empty meshes, time unit). GATE: issue list per file; nothing changed yet.
4. Safe fixes, then save a version. Only the allowed fixes; n-gons, non-manifold, facing, symmetry, units and joint orientation are reported, never fixed (FlippedNormals, ToWRH4IXF7A [00:11:50]). unlock_normals and influence caps are opt-in; caps refuse a weight move above 0.1 [added]. P.save_version() writes <out>/fixed/<stem>_fixed.ma. GATE: fix log per node; re-validation has no new failure.
5. Export. P.fbx_export(path, roots, "unreal_skeletal") (presets unreal_/unity_ + static, skeletal, anim; P.fbx_commands(preset) shows the MEL). Animation: bake range explicit, one clip per file for Unreal, joints only. Caches: P.abc_export (-uvWrite -writeFaceSets, from the composed shot). USD: P.usd_export(path, roots, frame_range=...). GATE: <file>.settings.json shows every option queried back; the FBX log was found and read (rep["fbx_log"], X05).
6. Verify in a clean scene. P.fbx_takes(path) (no import), P.reimport_stats(path), P.compare_stats(before, after); P.abc_verify; P.usd_verify. GATE: meshes, triangles, UV sets, joint names, per-mesh bounding boxes, normal directions (at most 2% moved), units and up axis match; takes = clips + Take001; USD default prim, time range, scheme none with normals, SkelRoot, metersPerUnit 0.01.
7. Report and diff. summary.json/summary.csv, P.export_manifest(summary), P.publish_diff(previous, current). Look at a sample (sheets of fixed files, the engine import). GATE: the report lists what was not verified.

The builtin job does stages 3 to 6 per file: P.batch(scenes, P.BUILTIN_EXPORT, out, plugins=("fbx",), job_args=["--preset", "unreal_skeletal", "--profile", "rig", "--fps", "30"]) (procedures.md P2).

Other jobs, same discipline (procedures.md): USD shot layers, one edit target, own and stronger layers muted (P9); references from the manifest, a clashing namespace raises (P10); OM2 reads through mx_audit.mfn_mesh, plug-ins and PySide6 panels (P12, P13); P.perf_census then P.eval_timing (P14); GUI parts through mx_bridge after checking modified (P15).

Numbers