Add Model Pipeline

Goal

Implement and verify the end-to-end FastVideo pipeline after the native components and converted weights have passed non-skip component parity. This skill owns pipeline class/stage wiring, pipeline configs, presets, registry entries, examples, smoke tests, and pipeline parity-debug.

FastVideo has one pipeline architecture: stage-based composition through ComposedPipelineBase. Add or specialize stages only when existing stages cannot represent the official behavior safely.

Hard Gate

Do not start pipeline work until every required component, including reused components, has a non-skip local parity PASS.

If any component row is missing, skipped, red, or blocked, return to /add-model Phase 6. Pipeline parity cannot distinguish stage wiring mistakes from broken component numerics when component parity is still unresolved.

Inputs

Follow ../add-model/shared/common_rules.md for token/auth safety, state files, escape hatches, production boundaries, and skip/pass semantics.

Require a complete packet matching ../add-model/contracts/pipeline_context.md.

The packet must include:

• official pipeline files and official call/default sources;
• workload types, input/output modalities, and output contract;
• converted or source model_index.json path;
• component parity rows, all non_skip_pass;
• target FastVideo pipeline/config/preset/registry/example/test paths;
• local_tests_readme and port_state_file paths.

Outputs

• Pipeline package under fastvideo/pipelines/basic/<family>/.
• Pipeline config under fastvideo/configs/pipelines/<family>.py or a documented family-local config file when that matches existing project style.
• Presets under fastvideo/pipelines/basic/<family>/presets.py.
• Registry updates in fastvideo/registry.py.
• Basic example under examples/inference/basic/basic_<family>*.py.
• Local smoke and parity tests under tests/local_tests/pipelines/.
• Updated tests/local_tests/<model_family>/README.md.
• Updated tests/local_tests/<model_family>/PORT_STATUS.md.
• Handoff matching ../add-model/contracts/pipeline_handoff.md.

Mode: Pipeline Definition

Use this mode first.

1. Read the official pipeline call path before editing FastVideo code.
2. Compare official defaults against the planned FastVideo config and presets: steps, CFG scales, secondary CFG, flow shift, schedulers, sigmas, seed/RNG, resolution, frames, FPS, duration, VAE scaling, decode slicing, negative prompt defaults, and output heads.
3. Create or update the pipeline class with _required_config_modules matching the emitted model_index.json and ComposedPipelineBase.load_modules. Runtime pipeline resolution is exact: model_index.json["_class_name"] must match a registered EntryClass.__name__, or a wrapper/alias class in EntryClass. Registry detectors do not select the executable pipeline class.
4. Add new public generation kwargs to fastvideo/api/sampling_param.py before examples or presets use them. SamplingParam.update() ignores unknown keys except for logging, and preset defaults apply only to declared fields. Add CLI args when the option should be available from command-line entrypoints.
5. Put loader-time changes in load_modules() or earlier, not initialize_pipeline(). ComposedPipelineBase.__init__ loads modules before post_init() calls initialize_pipeline(), so process-global flags, loader path rewrites, dtype overrides, and tokenizer path changes needed for loading cannot be introduced there.
6. Use self.get_module("transformer_2", None) and similar optional accessors for truly optional modules. Do not hard-require optional modules by accident.
7. Avoid mutating class-level _required_config_modules in custom code. If a pipeline needs dynamic modules, copy the list to an instance-owned value or pass required_config_modules explicitly so one pipeline instance cannot leak module requirements into another.
8. Create the stage chain in official execution order. Prefer existing shared stages for standard text encoding, timestep preparation, latent preparation, denoising, and decoding.
9. Add model-specific stages only for family-specific behavior that does not fit the shared stage contracts.
10. Add pipeline config classes for wiring and runtime defaults. Do not duplicate component architecture fields unless a loader requires them in the subconfig. Family-local config files such as fastvideo/pipelines/basic/<family>/pipeline_configs.py are valid only when fastvideo/registry.py imports and registers the classes explicitly.
11. Add InferencePreset objects with model_family, name, version, defaults, optional validation-only stage_schemas, and an ALL_PRESETS tuple. stage_schemas validates user-facing stage_overrides names; it does not drive create_pipeline_stages() execution.
12. Register config classes and presets in fastvideo/registry.py: add register_configs(...), import the family's ALL_PRESETS, and append it to _register_presets(). Detectors should cover HF paths and _class_name strings for config/preset lookup, but not as a replacement for exact pipeline class-name resolution.
13. Add a basic example with a user-story docstring and normal file-path inputs for image, audio, or video references. Keep orchestration glue in the pipeline or a helper, not in the example.
14. Add a separate smoke test tests/local_tests/pipelines/test_<family>_pipeline_smoke.py that proves imports, EntryClass, registry, presets, config defaults, and at least one real load/generate path when weights are local. Older local tests sometimes colocate smoke checks in parity files; new ports should use the separate file convention.
15. Add or update pipeline parity test scaffolding with templates/pipeline_parity_test.py.
16. Update local_tests_readme and port_state_file with commands, statuses, default sources, decisions, and blockers.

Production import boundaries are defined in ../add-model/shared/common_rules.md.

Mode: Pipeline Parity Debug

Run after pipeline definition and after smoke can execute far enough to load the pipeline. Loop until pipeline parity is a non-skip PASS or a precise blocker is returned.

Mandatory order:

pytest tests/local_tests/pipelines/test_<family>_pipeline_smoke.py -v -s
DISABLE_SP=1 pytest tests/local_tests/pipelines/test_<family>_pipeline_parity.py -v -s
python examples/inference/basic/basic_<family>.py

Pipeline parity must compare real outputs, not only successful generation:

• denoised latents when decode parity is expensive or nondeterministic;
• decoded videos/images when visual output should be deterministic enough;
• decoded waveform or audio features for audio pipelines;
• separate video and audio targets for joint AV pipelines unless a validated joint metric exists.

Debug pipeline drift in this order:

1. Confirm both sides use the same component weights and component parity PASS results are still valid.
2. Align official and FastVideo call arguments, presets, and default values.
3. Align scheduler timesteps, sigmas/noise levels, prediction type, flow shift, guidance math, and secondary-guidance branches.
4. Align RNG: initial latents/noise, generator device, seed, per-step noise, VAE sampling, and any official +1 frame or crop/slice behavior.
5. Align conditioning: prompt templates, negative prompts, masks, image/audio preprocessing, modality packing, text truncation, and dtype/autocast.
6. Align decode: latent scaling, per-channel mean/std, tiling flags, output channel order, sample rate, FPS, and final slicing.
7. Add targeted stage-level diagnostics to identify the first divergent stage.

If stage diagnostics show the first bad stage is transformer/denoising or a mid-DiT block, enable activation trace before adding ad hoc pipeline prints; see docs/contributing/activation_trace.md and ../add-model-08-trace/SKILL.md. Keep FASTVIDEO_TRACE_LAYERS, FASTVIDEO_TRACE_STATS, and FASTVIDEO_TRACE_STEPS identical across reruns so pipeline parity traces diff one-to-one.

If the first divergence belongs to component implementation, strict loading, or conversion mapping, stop pipeline edits and return next_step=return_to_phase_6 with the exact failing evidence. Do not patch conversion from this skill.

Stage And Variant Rules

• Canonical video T2V order: InputValidationStage, TextEncodingStage, ConditioningStage, TimestepPreparationStage, LatentPreparationStage, DenoisingStage, DecodingStage.
• Canonical video I2V delta adds image loading/encoding and image VAE encoding in the official order, commonly: TextEncodingStage, ImageEncodingStage, ConditioningStage, TimestepPreparationStage, LatentPreparationStage, ImageVAEEncodingStage, DenoisingStage, DecodingStage.
• Treat ConditioningStage as default-present for Wan-style pipelines, but still follow the reference if another family truly skips or replaces it.
• T2V video pipelines usually use validation, text encoding, conditioning, timestep preparation, latent preparation, denoising, and decoding.
• I2V adds image loading/encoding and image-latent preparation according to the official pipeline, not by assuming CLIP or Wan-specific branches.
• Pick image, audio, and video encoders from the reference. Do not assume CLIP or any other common encoder unless the reference uses it.
• Cross-attention class names are not prescribed; match the family style and preserve the official tensor contract.
• WorkloadType currently has no T2A, A2A, or AV values. Until that enum is extended, audio-only pipelines may register with WorkloadType.T2V and preset workload_type="t2v" as a compatibility shim, but must document the rationale in code and PORT_STATUS.md.
• Audio-only pipelines should not force real video semantics into presets. Use minimal video-shaped placeholders such as small height/width and num_frames=1 only when shared VideoGenerator/validation paths require them, and document that the real output is audio.
• Record modality-specific shape knobs and output contract in the pipeline handoff: video uses height, width, num_frames, and fps; audio uses audio_seconds and sampling_rate; joint AV records both plus whether output is muxed or paired files.
• Use sibling pipeline classes/configs when required modules, HF repo layout, stage chains, or inputs differ materially.
• Use one kwargs-driven pipeline class only when variants share weights, modules, stage chain, and safe call semantics.
• Split later if components diverge, workload tags require separate discovery, signatures become unsafe, or stage branches become substantial.
• If the DiT branches on added_kv_proj_dim, document the T2V/I2V split.
• If the reference uses transformer_2, boundary_ratio, guidance_scale_2, or DMD step lists, keep those on config, presets, or stages deliberately.
• Support every official output head in scope. If a head is out of scope, record explicit user approval in PORT_STATUS.md.

Pipeline verification order:

pytest tests/local_tests/pipelines/test_<family>_pipeline_smoke.py -v -s
DISABLE_SP=1 pytest -v -s tests/local_tests/pipelines/test_<family>_pipeline_parity.py
python examples/inference/basic/basic_<family>.py

Smoke tests prove loadability only. They are not a substitute for numerical component or pipeline parity.

Escape Hatches

Follow ../add-model/shared/common_rules.md. Pipeline-specific ask cases include dropping a public mode, modality, or output head; adding a new workload enum; changing official defaults for user-facing behavior; accepting a known pipeline parity blocker; running GPU-heavy quality work outside the agreed scope; or publishing/uploading generated references or converted weights.

Handoff

Return ../add-model/contracts/pipeline_handoff.md and update the shared state files before handoff.

Do not hand back a green pipeline if smoke or parity skipped locally. A skip is a setup gap, not a pass.

References

• fastvideo/pipelines/composed_pipeline_base.py for module loading and stage execution.
• fastvideo/pipelines/basic/wan/ for standard video T2V/I2V/DMD variants.
• fastvideo/pipelines/basic/stable_audio/ for audio-specific stage composition.
• fastvideo/configs/pipelines/stable_audio.py and fastvideo/pipelines/basic/stable_audio/presets.py for config/preset shape.
• fastvideo/registry.py for register_configs(...) and preset registration.
• tests/local_tests/pipelines/test_gamecraft_pipeline_parity.py for latent parity structure.
• tests/local_tests/pipelines/test_stable_audio_pipeline_parity.py for audio parity structure.
• tests/local_tests/pipelines/test_stable_audio_pipeline_smoke.py for no-GPU import/registry/preset preflight shape.