Cosmos3 TAO training

Keep one shared model-facing frontend. Backend image fields and contract paths live under backend_contracts in references/skill_info.yaml; image literals are stamped from versions.yaml, while referenced backend YAMLs define native runtime schemas. Never translate between them.

Mandatory runtime intake

Before planning training, collect all of the following. Do not infer a path from history, another user, a prior job, an image, or a developer checkout.

• base_model_path_or_uri. For a Hugging Face model ID or URL, accept an optional friendly base_model_revision such as a branch or tag. If omitted, resolve main; do not ask the user for a commit SHA. Resolve the selected ref read-only through the Hub API to its immutable commit and seal the model ID, requested ref, and resolved SHA in the plan. A complete local snapshot needs no revision and is sealed by its file fingerprints.
• For Cosmos3-Nano, an explicit input-checkpoint model_type: qwen3_vl or cosmos3_omni. If the user did not supply it, ask once before planning; never infer the choice from config.json, a model ID, a path name, or a previous run. Explain the two choices in plain language: qwen3_vl uses a compatible Hugging Face checkpoint directly, while cosmos3_omni requires an immutable conversion to exact Qwen3-VL safetensors before training. Record the answer as base_model_format. Cosmos3-Edge is inferred as cosmos3_edge from the resolved model ID and does not present this Nano-only choice.
• Do not expose Omni preparation implementation fields during normal intake. For Nano, use the packaged Qwen/Qwen3-VL-8B-Instruct architecture mapping, resolve both Hub models to immutable commits automatically, and run the TAO-owned cosmos_rl.model_preparation.vlm_safetensors entrypoint with the already selected backend image/SQSH. Both backend images must package that entrypoint and its pinned native Framework conversion runtime. An explicitly supplied prepared_checkpoint_path or donor is an advanced override: validate it, but never present a route A/B choice or ask for one by default.
• Accept hf_model://nvidia/Cosmos3-Nano directly. If a gated/private model cannot be resolved, ask the user only to set HF_TOKEN in the session environment; never ask them to discover a SHA or provide the token value in chat.
• explicit video sampling mode: either uniform nframes or fps. FPS mode may also set min_frames and max_frames; both modes may set clip-time, resize, and pixel-budget fields supported by the selected backend.
• training/validation annotation paths and media roots for conversation-style or task-aware video supervision, plus optional task selection.
• explicit backend for a comparison; cosmos-framework or cosmos-rl.
• training_mode; dense or peft. PEFT also requires rank, alpha, dropout, target modules, bias, RS-LoRA, modules-to-save, and adapter precision.
• user-owned results_dir, checkpoint_dir, cache_dir, and, for SLURM, sqsh_cache_dir, ssh_key_path, mounts, and scheduler settings.
• Runtime order: compute-readable sqsh_path, explicit image, then the selected backend image in references/skill_info.yaml. On SLURM reuse or convert it once under sqsh_cache_dir. Never compare an SQSH filename with an image tag or request source provenance/SHA.
• Repository paths, commits/trees, branch, base image, build context, and timestamp are advanced inputs required only for explicit source-build. See references/cosmos-backend-operations.md; never infer a build from runtime selection.

The planner preserves each original path and reports an accessible realpath. Missing required paths fail. A missing supplied SQSH fails; an omitted SQSH selects the packaged image. No historical fallback path or image is allowed.

Nano checkpoint model-type choice

Treat the selected base_model_format as a user decision and verify that it matches the supplied local checkpoint's config.json.model_type. A mismatch fails; it is not permission to relabel or rewrite the source checkpoint.

For qwen3_vl, fingerprint and use a complete compatible Hugging Face Nano checkpoint directly. For cosmos3_omni, tell the user in the launch review that Cosmos-RL will prepare its compatible checkpoint automatically, name the planned output path, and preserve the source checkpoint unchanged. Do not ask the user for an architecture donor, preparation image, or preparation SQSH. The backend-owned preparation step emits a verified qwen3_vl checkpoint under the selected platform's user-owned checkpoint_dir:

• Docker: the local Docker host's checkpoint_dir.
• SLURM: the compute-node-verified shared checkpoint_dir, covered by an explicit container mount. Run conversion through the SLURM/Pyxis contract; do not write the converted checkpoint to controller-local storage.

Use the packaged Nano architecture mapping and selected backend runtime unless an advanced override was explicitly supplied. Fingerprint the source, architecture mapping, converted config/tokenizer/processor/index/shards, and conversion provenance. Before conversion, bind the sealed plan's backend-native training fields and VLM_SAFETENSORS_PATH to the planned converted checkpoint inside the selected container. Validate that exact output before training without mutating the sealed plan. The original Omni/Hugging Face path remains provenance only and must never remain as the runtime model path. Reuse is allowed only when the exact target has complete matching conversion provenance and passes the same validation.

Public Cosmos3-Edge checkpoint contract

Accept the public model at its resolved immutable revision or a local snapshot; never request a second checkpoint. Apply the model-aware runtime defaults from references/skill_info.yaml and references/cosmos-framework-backend.yaml, preserving separate model and processor-profile fingerprints and each default/override origin.

Backend selection

Run scripts/cosmos_workflow.py resolve first.

An explicit supported backend wins, so users can select Cosmos Framework for Nano training without changing model ownership. Comparative runs reject auto, so both sides of an experiment are deliberately forced. Framework-trained checkpoints use the native exact-key exporter, then the repository-backed TAO evaluation adapter. That does not make Framework a Cosmos-RL version.

Evaluation intake and inheritance

Run scripts/evaluation_workflow.py for every evaluate action and follow references/cosmos-reason-evaluate.md completely. A parent training plan owns all inheritable model, dataset, prompt, preprocessing, precision, checkpoint, and scoring fields; never ask the user to repeat them. Ask once only for the helper's required_user_inputs, execute its automated_actions, and launch only a checksum-valid ready=true plan. Cosmos-RL policy checkpoints require the emitted cosmos_rl_checkpoint_pre_action; Framework DCP inputs require their emitted export pre-action. The ready plan includes a validated spec_bundle.execution; pass it unchanged to the selected platform. Cosmos owns runtime attestation and evaluator configuration; the platform owns launch.

Framework checkpoint pre-action

Before Framework evaluate, inference, or microservice actions, run scripts/framework_checkpoint_action.py plan and its emitted prepare and verify steps. Follow references/cosmos-backend-operations.md; never ask the user to export DCP manually. On SLURM stage only the helper dependency set declared by workflow_contract.action_helper_dependencies; the platform verifies the closed bundle. Use only the verified action_model_path, reuse only matching complete exports, and record the pre-action, manifest, fingerprints, and independent child result.

Required gates

Execute these stages in order and persist their outputs.

1. Resolve model/backend/action and load the selected backend contract.
2. Check credentials by presence only. Never read or persist credential values. Require a token only for the operation that needs it.
3. Validate tools, storage, paths, and runtime selection in the mandatory intake order; existing-SQSH and packaged-image modes skip source gates.
4. Only for explicit source-build, validate/build clean sources and verify /opt/tao/image-provenance.json. Never mount host source into training.
5. Enforce the explicit Nano checkpoint model-type choice. If it is cosmos3_omni, show the conversion and platform-owned output path in the launch review, then prepare the model through the shared TAO integration entrypoint packaged in the selected clean backend image after approval. Resolve URI/model-ID refs to immutable Hub commits automatically. Validate exact tensor/config keys and fingerprint model, tokenizer, processor, weight index, every shard, and provenance. Assign the verified converted path—not the original source path—to training.
6. Validate inputs, counts, duplicates, overlap, tasks, and identities. A no-byte-hashing request selects both fast fingerprint flags; metadata stays hashed while weight/media payloads use path+size. Verify the resolved inputs again from an allocated compute node. When SLURM storage is not mounted on the launch host, let cosmos_workflow.py stream its checked-in cosmos_common.py inspector to a login host over SSH. It runs from stdin, preserves remote realpath values, and creates no remote script or source overlay. Do not require local Lustre, sbatch, or srun on an SSH-based launch host. Run this expensive input inspection exactly once with the plan verb and pass a local --plan-artifact <path> so the resolved request and inspection results are sealed for the remaining launch verbs.
7. Resolve the video runtime from the structural dataset contract and enforce every profile gate in references/cosmos-reproducibility-gates.md. Cosmos-RL auto selects source-baked pynv-device-rgbp for video_conversation and system-pyav for task_aware_video_reasoning; Framework selects torchcodec-cuda-on-demand. All defaults use bounded rank-local, on-demand memory with no disk prewarm. Repeated-media validation may use the backend-native grouped sharder and validation-only caches only while preserving records, explicit batch, weighting, prompts, and preprocessing. Throughput settings that relax batch-1 parity require user authorization.
8. Generate backend-native TOML, environment, topology, preflight commands, parity data, runtime profile, and metadata. Full specs contain no sample limit. Reuse one sealed --plan-artifact across read-only preflight, post-review materialize, and render-slurm; do not repeat original inputs. Materialize atomically in the verified compute frame, derive container paths only from explicit mounts, and never copy source patches to the cluster. Diagnostic subsets are explicit opt-ins, never launch prerequisites.
9. On SLURM reuse the supplied/derived SQSH or convert the selected image once before GPU submit. SQSH SHA and source provenance are not runtime gates. When Omni preparation is required, inspect the SQSH filesystem and reject it unless it contains the shared TAO launcher, the native Framework converter, and /opt/tao/framework-converter-runtime.json. The runtime artifact must report validation_mode=imported_converter_module, proving the isolated converter's transitive dependency graph imported during the image build; file presence alone is not sufficient. Verify Pyxis/Enroot, mounts, Python/packages, decoder, GPU, CUDA, NCCL, and storage in the training allocation.
10. Launch the requested training job directly; do not submit a separate smoke job unless the user explicitly requests one. For Cosmos-RL VLM training, require packaged source that emits a padding-aware attention_mask and runs the visual-gradient contract after the first backward pass and before the first optimizer update. Persist total/trainable/frozen counts and gradient norms for the vision encoder, visual projector, language model, and language head. Fail immediately when a trainable visual component has no gradient, a non-finite norm, or a zero norm. Report an explicitly frozen visual component as not applicable rather than as a failure.
11. Materialize the full spec once and verify its SHA256 in the compute frame before rendering the job from the same plan artifact. Monitor scheduler and structured TAO state to a terminal result, and preserve the child exit code independently of scheduler state. Require child exit zero, structured SUCCESS, finite global train/validation loss, checkpoint completion, and a final evaluator metric before reporting completion.
12. Resolve evaluation with scripts/evaluation_workflow.py. Inherit exact fine-tuning artifacts, collect only its remaining user inputs, run its backend-owned automated checkpoint pre-actions, and require ready=true. On Cosmos-RL, verify the selected HF export with cosmos_rl_checkpoint_action.py, rerun resolution with its manifest, and submit the emitted spec-bundle through the chosen platform; never select the native policy directory, copy the lifecycle into an application-owned launcher, or improvise result/status variables. Evaluate the selected checkpoint with identical prompt, preprocessing, generation, normalization, and task scoring. Extract final metrics with scripts/extract_cosmos_metrics.py.

Dataset contracts

Resolve datasets by structure, not by project, benchmark, directory, or file name. The supported families are:

• video_conversation: a JSON array with media and at least two ShareGPT, LLaVA, or OpenAI-style conversation turns;
• task_aware_video_reasoning: one or more item-envelope or array annotation files with media, task identity, and conversation/response targets.

Default dataset_family to auto, inspect every annotation, and require train and validation to resolve to the same family. Capture record count, unique media count, media reuse, extensions, byte-size distribution, task/metric metadata, and any declared width, height, FPS, and duration. Select processor, cache and resource profiles from those characteristics and the model tier. Never branch on a customer dataset name.

Tasks declaring accuracy participate in deterministic accuracy; common binary and multiple-choice task types are recognized. Generative tasks report their declared metrics and are excluded from aggregate accuracy with a reason. Aggregate accuracy is example-weighted over records with an accuracy definition.

Dense and PEFT contracts

Dense SFT has no LoRA block and reports trainable, frozen, and total counts. PEFT preserves rank, alpha, dropout, targets, bias, RS-LoRA, saved modules, precision, and trainable count across backends; mismatched semantics block a pair.

For fair comparisons, force the same logical model, train/validation records, media, prompt, frames, sequence length, precision, seed, epochs, effective global batch, optimizer, learning rate, schedule, warmup, weight decay, clipping, loss masking, validation/checkpoint cadence, evaluated checkpoint, and generation/normalization settings. Classify differences as equivalent syntax, unavoidable implementation difference, or invalid mismatch; an invalid mismatch blocks the full pair.

Metrics and completion

The required primary metrics are:

• complete-run globally reduced token-weighted training loss, with numerator and valid-label denominator;
• final-validation globally reduced token-weighted loss, with numerator and valid-label denominator;
• the repository evaluator's final validation metric and any supporting values it emits. Do not add a second post-evaluation gate.

Do not average console lines or rank means. A step loss is not the average training loss. A validation heartbeat is not final validation loss. A generative exact match is not accuracy unless the task defines it.

The native Framework callback and native Cosmos-RL logger own early failure, checkpoint, progress, metric, and terminal events. Do not stage a status bridge or patch status at container startup. COMPLETED from SLURM is failure when the child exit code is nonzero or the terminal TAO state is not successful.

SLURM invariants

Generated jobs use Bash, SQSH via Pyxis, no requeue by default, one launcher task per node, runtime-supplied logs, and the training child exit code. A single-node exclusive allocation preserves the requested CPU count in the SBATCH contract but passes every CPU actually granted by SLURM to the training step and records requested, allocated, and step counts. Before the training child, the same allocation runs the planner-owned packaged-runtime gate as the training job's first Pyxis step; a failed gate writes the independent child exit artifact and blocks training. Generated jobs set SLURM_EXPORT_ENV=ALL, and the platform consumer still submits with sbatch --export=ALL. Every Pyxis step also receives the planner-owned runtime variable names through --container-env, so a baked image ENV value cannot override the selected decoder, frame-transfer, cache, or worker profile. Framework topology is shard=gpus_per_node, replica=nodes. Cosmos-RL uses one controller on node zero and its policy-worker topology. Asynchronous distributed checkpointing is rejected for multi-node runs.

Every job metadata record must validate against schemas/cosmos-job-metadata.schema.json and contain paths, fingerprints, runtime identity, config, resources, states, outputs, and timing without credentials. Source provenance exists only for source-build; SQSH SHA is optional and never a runtime gate.

Source-affecting recovery

If a run exposes a code or image defect, stop the affected path, change the owning repository, add a test, commit it, rebuild both image and SQSH from a clean checkout, then restart every affected training job from its clean sealed plan. Never edit a running container, patch an existing image, reuse an old SQSH after a source change, or rely on a temporary launch script as the implementation.

Use references/cosmos-reproducibility-gates.md as the source-owner/test map.

For infrastructure retries, the launch skill classifies the failure and opens the new --retry-of record; SLURM supplies validated node inventory and exclusions. Run cosmos_workflow.py retry-plan with the new record's <action-root>/config/train.toml; it rebases all writable paths and reseals the Cosmos request. Render that plan; never patch SBATCH.