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Kermt Add Cmim Pretrain

NVIDIAOfficialPublished by NVIDIA

  • Skill
  • Workflow
  • Software development
  • Apache-2.0
  • Medium risk
  • Has scripts

From the author

Convert a grover_base checkpoint (encoder-only or encoder + vocab heads) into a hybrid checkpoint by adding a randomly-initialized cMIM decoder + latent_dist, then continue pretraining on the user's corpus as hybrid (vocab + contrast). Effectively kermt-continue-pretrain with a one-time ckpt-conversion step prepended.
— the description by NVIDIA

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This workflow converts an existing grover_base checkpoint (encoder-only or with vocab heads) into a hybrid model by adding a randomly-initialized cMIM decoder and latent distribution. It then proceeds to continue pretraining on the user's provided corpus. This process allows users to incorporate contrastive objectives into their models without the computational cost of restarting pretraining from scratch.

What it does

  • Validates the input checkpoint to ensure it is suitable for hybrid conversion.
  • Prepares the training data and builds a fresh vocabulary from the user's corpus.
  • Upgrades the checkpoint by adding a cMIM decoder and latent distribution.
  • Launches a detached pretraining run using the newly created hybrid checkpoint.
  • Provides audit logs and provenance for the upgraded checkpoint.

When to use it

  • When you have a grover_base checkpoint and want to add SMILES-reconstruction contrastive objectives.
  • When you want to extend an existing model's capabilities without performing a full from-scratch pretraining run.
  • When you need to adapt a pretrained encoder to a new corpus while maintaining hybrid training objectives.

Advantages

  • Saves significant time compared to restarting pretraining from scratch.
  • Enables the use of contrastive learning objectives on existing encoder-only models.
  • Maintains provenance by capturing upgrade summaries and input manifests.
  • Ensures data integrity through automated validation of checkpoints and corpora.

Usage examples

“Upgrade my grover_base checkpoint at ./models/base.pt to a hybrid model using my new dataset at ./data/corpus.csv.”
The agent validates the checkpoint, prepares the data, creates an upgraded hybrid checkpoint, and initiates the continue-pretraining process.

Install

  1. Download the skill as a ZIP:

    https://autogineer.com/agent-skills/nvidia/kermt-add-cmim-pretrain/download
  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip kermt-add-cmim-pretrain.zip -d .agents/skills

Documentation by NVIDIA

kermt-add-cmim-pretrain

Convert a grover_base checkpoint (legacy original-GROVER grover.encoders.* or modern kermt.encoders.*, with or without vocab heads) into a fully-formed hybrid (cMIM + vocab) checkpoint, then continue pretraining on the user's corpus as hybrid.

This is a thin wrapper: upgrade_to_hybrid.py produces a new ckpt that classifies as model_type: hybrid via check_checkpoint.py, and the rest of the workflow is identical to kermt-continue-pretrain.

Status: experimental. This workflow is functional end-to-end but has not been benchmarked against the manuscript's from-scratch hybrid training (which produces the released checkpoint). Use as an experimental alternative to kermt-pretrain-scratch when you want to extend an existing grover_base checkpoint rather than restart from random init. Validate downstream performance on your own benchmark before relying on the upgraded ckpt for production work.

Skill and runtime paths

Set SKILL_DIR to the absolute path of this installed skill directory. Export KERMT_REPO as the absolute path to the KERMT checkout used for model execution. The bundled container helper mounts that checkout at /workspace and this skill at /skill (read-only). Commands inside the container use /skill/scripts/; defaults are bundled in config/.

Hardware requirements

Same as kermt-continue-pretrain (the cMIM decoder adds parameters but not substantially; VRAM headroom should be fine). The upgrade step itself is fast (~5 s) and CPU-only — only the subsequent continue-pretrain consumes GPU.

When to invoke

  • User has a grover_base checkpoint (encoder-only or with vocab heads) and wants to extend it into a hybrid (vocab + cMIM contrastive) pretrain.

  • Useful for adding the SMILES-reconstruction contrastive objective to a pretrained encoder without restarting pretraining from scratch (which kermt-pretrain-scratch would do at days-scale).

For continuing an existing hybrid or cmim ckpt: use kermt-continue-pretrain directly. For training a fresh model on a custom corpus: use kermt-pretrain-scratch.

Inputs

Required:

  • --ckpt <path> — grover_base ckpt to upgrade. Validated via check_checkpoint.py --mode upgrade_to_hybrid; rejected if the ckpt already has a contrast head or task FFN.

  • --csv <path> — pretrain corpus CSV. Same shape as kermt-continue-pretrain's --csv input.

Optional (same as kermt-continue-pretrain):

  • --val-csv <path> — separate validation CSV. Without it, prepare_data auto-splits by --val-frac 0.1.

  • Training-hyperparameter overrides (--epochs N, --batch-size N, lr triple, --warmup-epochs F, etc.).

  • --vocab-loss-weight F / --latent-dim N / --contrastive-temperature F.

  • --wandb-project NAME / --wandb-run-name NAME — optional Weights & Biases logging (run name honored only alongside a project). Off by default.

  • --gpus 0,2.

Workflow

Let $KERMT_REPO be the path to your kermt repo checkout.

  1. Pre-flight: check_system (same as kermt-continue-pretrain step 1).

  2. Compute run directory:

    RUN_DIR=$KERMT_REPO/runs/add-cmim-pretrain_$(date -u +%Y-%m-%dT%H-%M-%SZ)
  3. Validate the input ckpt with check_checkpoint --mode upgrade_to_hybrid. Abort on ok: false. The validator rejects ckpts that already have contrast head (suggest kermt-continue-pretrain) or task FFN heads (the ckpt has been finetuned; suggest using the original pretrain checkpoint).

  4. Validate the corpus via check_data --mode pretrain. Abort on ok: false.

  5. Prepare the data with --mode pretrain — without --vocab-dir. The upgrade builds fresh vocab heads sized to the corpus's vocab, so we want prepare_data to produce a new vocab from the corpus rather than passing through the ckpt's old vocab (which may not even exist for encoder-only legacy grover_base ckpts):

    "$SKILL_DIR/scripts/kermt_container.sh" run --data <user-csv> --run-dir $RUN_DIR -- \
        "python /skill/scripts/prepare_data.py --mode pretrain \\
             --csv /data/<basename> --out /runs/data \\
             [--val-csv /data/<val-basename>] [--val-frac 0.1] [--seed 0]"

    The output manifest has vocab_source: "built_fresh" and includes a smiles_vocab (built from the corpus, needed for the new decoder).

  6. Upgrade the ckpt.

    "$SKILL_DIR/scripts/kermt_container.sh" run --ckpt <user-ckpt> --run-dir $RUN_DIR -- \
        "python /skill/scripts/upgrade_to_hybrid.py \\
             --ckpt /ckpt \\
             --prepare-manifest /runs/data/prepare_data.json \\
             --out /runs/upgraded.pt"

    Surface the JSON summary to the user — especially warnings[], which includes any encoder-arch drift notes (e.g. legacy GROVER had two extra act_func_* keys that modern KERMTEmbedding doesn't) and the pretrain_ddp.py --backbone argparse-restriction note if the upgraded ckpt's backbone is anything other than gtrans.

  7. Estimate runtime + confirm with the user. Same heuristic as kermt-continue-pretrain (corpus size × epochs × GPU count → wall time).

  8. Launch the runner detached.

    "$SKILL_DIR/scripts/kermt_container.sh" run_detached \\
        --name kermt-add-cmim-pretrain-<ts> \\
        --run-dir $RUN_DIR -- \\
        "python /skill/scripts/run_pretrain_local.py \\
             --ckpt /runs/upgraded.pt \\
             --prepare-manifest /runs/data/prepare_data.json \\
             --out /runs \\
             [--epochs N --batch-size N ...]"

    The runner sees the upgraded ckpt as model_type: hybrid, so it auto-dispatches --pretrain_mode hybrid --vocab_loss_weight 1.0 with smiles_vocab plumbed through.

  9. Report to the user with the upgraded ckpt path + the same run.json pointer / log path / tensorboard URL pattern as kermt-continue-pretrain.

Hard rules

  • Never modify the user's input ckpt. The upgrade writes a new file at <run_dir>/upgraded.pt; the source ckpt stays untouched.

  • Vocab heads are always fresh. Even if the input grover_base has vocab heads, they're discarded and rebuilt sized to the new corpus's vocab. Continue-pretraining the upgraded ckpt will train those new heads alongside the decoder.

  • Don't auto-relax --backbone choices. If the upgrade warning fires because the input ckpt's backbone isn't gtrans (e.g. legacy dualtrans), surface the warning and ask the user. Do NOT silently modify parsing.py to add the legacy backbone to the choices list.

Common errors

  • check_checkpoint rejected the ckpt with model_type=hybrid or cmim → user's ckpt already has a contrast head. Redirect to kermt-continue-pretrain.

  • check_checkpoint rejected the ckpt with task_ffn=true → the ckpt has been finetuned. The upgrade workflow only supports pretrain checkpoints.

  • prepare manifest missing smiles_vocab → prepare_data was invoked with --skip-vocab or some equivalent that omitted the smiles vocab. Re-run prepare without those flags.

  • unexpected key(s) in encoder load warning → legacy GROVER architectures saved a couple of act_func_* weights that modern KERMTEmbedding doesn't use. Benign; the rest of the encoder loaded correctly.

What's in run.json after a successful run

Same reproducibility fields as kermt-continue-pretrain, plus the upgrade step's summary.json is captured under the inputs.upgrade_summary path so the provenance of the upgraded ckpt is auditable.

Replayability

Same as kermt-continue-pretrain: cmd_replay rebuilds the run_pretrain_local.py --ckpt <upgraded.pt> ... invocation. To redo the full add-cmim flow end-to-end, the user also needs the input grover_base ckpt and the corpus — both are captured in the prepare_data and upgrade manifests by absolute path.

Files

scripts/check_data.py

#!/usr/bin/env python3
# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0

"""Validate a CSV input for a given KERMT agent workflow.

Mode-dispatched. Emits a single JSON object to stdout that the calling skill
parses to decide whether to proceed (`ok: true`) or surface a structured error
back to the user (`ok: false` with `errors[]`). The JSON shape is stable
across modes; only the contract for what counts as `ok` differs per mode.

Modes
-----
pretrain    Pretrain corpus CSV. Requires a `smiles` column. Other columns
            are ignored. Label columns are not required (and not expected).

finetune    Labeled CSV for a downstream task. Requires `smiles` plus
            >=1 numeric target column. Target columns are specified via
            `--targets <col1> <col2> ...`. If `--targets` is omitted, the
            validator auto-detects numeric non-smiles columns and reports
            them; the skill will then prompt the user to confirm or refine.

inference   CSV to run predictions on. Requires `smiles`. Target columns are
            not required (and not expected — predictions are written out).

embed       CSV to extract embeddings from. Requires `smiles` only.

SMILES validation
-----------------
By default the validator samples up to 20 SMILES (first 10 + last 10) and
checks each one parses with RDKit. Pass `--strict-rdkit` to parse every
SMILES (slow on large corpora). A SMILES is considered "invalid" if RDKit
returns `None` from `MolFromSmiles(smi, sanitize=True)` — empty / null
rows are counted separately.

Duplicate-SMILES detection is always full (cheap).

Output (stdout)
---------------
{
  "ok": true | false,
  "mode": str,
  "csv_path": str,
  "num_rows": int,
  "num_columns": int,
  "columns": [str, ...],
  "has_smiles_column": bool,
  "smiles_column_name": str | null,    // actual header used (may differ in case)
  "num_blank_smiles": int,
  "num_invalid_smiles": int,           // among the parsed sample
  "smiles_check_method": "sampled" | "full",
  "smiles_check_count": int,
  "num_duplicate_smiles": int,
  "target_columns": [str, ...],        // populated only for finetune mode
  "num_missing_per_target": { col: int, ... },
  "auto_detected_targets": [str, ...], // when --targets is omitted in finetune mode
  "errors": [str, ...],
  "warnings": [str, ...]
}

Exit code: 0 on `ok: true`, 1 on `ok: false`. Loader exceptions are caught
and surfaced into `errors[]` with `ok: false` (still exit 1).

CLI
---
    check_data.py --mode <mode> --csv <path>
                  [--targets <col1> <col2> ...]   # finetune only
                  [--strict-rdkit]                # full SMILES parse
"""
from __future__ import annotations

import argparse
import json
import sys
import traceback
from pathlib import Path
from typing import Any

import pandas as pd


CANONICAL_SMILES_COLUMN = "smiles"
SMILES_SAMPLE_PER_END = 10  # how many SMILES from head + how many from tail to sample


def _find_smiles_column(columns: list[str]) -> str | None:
    """Return the actual column header matching 'smiles' case-insensitively, or None."""
    for c in columns:
        if c.lower() == CANONICAL_SMILES_COLUMN:
            return c
    return None


def _parse_smiles_sample(smiles_values: list[str], full: bool) -> tuple[int, int, str]:
    """Run RDKit MolFromSmiles on a sample or all of the SMILES. Returns
    (num_parsed, num_invalid, method)."""
    # Import here so the script can still surface a clean JSON error if RDKit
    # is unavailable in the host env.
    try:
        from rdkit import Chem
        from rdkit import RDLogger
        RDLogger.DisableLog("rdApp.*")  # suppress per-mol parse warnings
    except ImportError as exc:
        raise RuntimeError(
            f"RDKit is not importable in this environment: {exc}. "
            "Run check_data.py inside the kermt container."
        ) from exc

    if full or len(smiles_values) <= 2 * SMILES_SAMPLE_PER_END:
        sample = smiles_values
        method = "full"
    else:
        sample = smiles_values[:SMILES_SAMPLE_PER_END] + smiles_values[-SMILES_SAMPLE_PER_END:]
        method = "sampled"

    invalid = 0
    parsed = 0
    for smi in sample:
        if not smi:  # already counted as blank elsewhere
            continue
        parsed += 1
        mol = Chem.MolFromSmiles(smi, sanitize=True)
        if mol is None:
            invalid += 1
    return parsed, invalid, method


def _autodetect_target_columns(df: pd.DataFrame, smiles_col: str) -> list[str]:
    """Pick columns that look like numeric targets. A column qualifies if it
    is (a) not the smiles column and (b) >=80% of non-null values convert to float.
    Heuristic only — returned for the skill to prompt the user to confirm."""
    candidates: list[str] = []
    for col in df.columns:
        if col == smiles_col:
            continue
        ser = df[col].dropna()
        if len(ser) == 0:
            continue
        try:
            converted = pd.to_numeric(ser, errors="coerce")
        except (TypeError, ValueError):
            continue
        if converted.notna().sum() / max(len(ser), 1) >= 0.8:
            candidates.append(col)
    return candidates


def validate(mode: str, csv_path: str, targets: list[str] | None, strict_rdkit: bool) -> dict[str, Any]:
    result: dict[str, Any] = {
        "ok": False,
        "mode": mode,
        "csv_path": csv_path,
        "num_rows": 0,
        "num_columns": 0,
        "columns": [],
        "has_smiles_column": False,
        "smiles_column_name": None,
        "num_blank_smiles": 0,
        "num_invalid_smiles": 0,
        "smiles_check_method": "sampled",
        "smiles_check_count": 0,
        "num_duplicate_smiles": 0,
        "target_columns": [],
        "num_missing_per_target": {},
        "auto_detected_targets": [],
        "errors": [],
        "warnings": [],
    }

    # 1. Read the CSV.
    path = Path(csv_path)
    if not path.is_file():
        result["errors"].append(f"CSV not found: {csv_path}")
        return result
    try:
        df = pd.read_csv(path)
    except pd.errors.EmptyDataError:
        result["errors"].append(f"CSV is empty (no header): {csv_path}")
        return result
    except Exception as exc:  # noqa: BLE001
        result["errors"].append(f"failed to read CSV {csv_path}: {type(exc).__name__}: {exc}")
        return result

    result["num_rows"] = int(len(df))
    result["num_columns"] = int(len(df.columns))
    result["columns"] = [str(c) for c in df.columns]

    # 2. Locate the SMILES column.
    smiles_col = _find_smiles_column(result["columns"])
    if smiles_col is None:
        result["errors"].append(
            f"no column named 'smiles' (case-insensitive) found in CSV. "
            f"Available columns: {result['columns']}"
        )
        return result
    result["has_smiles_column"] = True
    result["smiles_column_name"] = smiles_col
    if smiles_col != CANONICAL_SMILES_COLUMN:
        result["warnings"].append(
            f"SMILES column is named '{smiles_col}' but downstream code expects '{CANONICAL_SMILES_COLUMN}' "
            f"(lowercase). Rename the column to '{CANONICAL_SMILES_COLUMN}' before running the workflow."
        )

    # 3. Blank-SMILES count + duplicate count + RDKit parse check.
    smi_series = df[smiles_col].astype(str).fillna("").str.strip()
    blank_mask = smi_series.eq("") | smi_series.str.lower().eq("nan")
    result["num_blank_smiles"] = int(blank_mask.sum())

    nonblank = smi_series[~blank_mask]
    result["num_duplicate_smiles"] = int(len(nonblank) - nonblank.nunique())

    if len(nonblank) == 0:
        result["errors"].append("no non-blank SMILES found in the CSV")
        return result

    try:
        parsed, invalid, method = _parse_smiles_sample(nonblank.tolist(), full=strict_rdkit)
    except RuntimeError as exc:
        result["errors"].append(str(exc))
        return result
    result["smiles_check_count"] = parsed
    result["num_invalid_smiles"] = invalid
    result["smiles_check_method"] = method

    if invalid > 0:
        scope = "all rows" if method == "full" else f"the {parsed} sampled rows"
        result["errors"].append(
            f"{invalid} out of {parsed} SMILES in {scope} failed to parse with RDKit. "
            "Either pre-clean the CSV with scripts/clean_smiles.py or pass --strict-rdkit to see "
            "the full count."
        )

    # 4. Target-column handling — finetune mode only.
    if mode == "finetune":
        if targets:
            missing = [t for t in targets if t not in df.columns]
            if missing:
                result["errors"].append(
                    f"target column(s) not found in CSV: {missing}. "
                    f"Available columns: {result['columns']}"
                )
            else:
                result["target_columns"] = list(targets)
                for t in targets:
                    nan_count = int(df[t].isna().sum())
                    result["num_missing_per_target"][t] = nan_count
                    # Confirm numeric-ish.
                    nonnan = df[t].dropna()
                    converted = pd.to_numeric(nonnan, errors="coerce")
                    non_numeric_count = int(converted.isna().sum())
                    if non_numeric_count > 0:
                        result["warnings"].append(
                            f"target column '{t}' has {non_numeric_count} non-numeric value(s) "
                            f"that will be dropped by the finetune runner."
                        )
        else:
            # Auto-detect — surface candidates so the skill can prompt the user.
            result["auto_detected_targets"] = _autodetect_target_columns(df, smiles_col)
            if not result["auto_detected_targets"]:
                result["errors"].append(
                    "no numeric non-smiles columns detected. finetune needs at least one target column; "
                    "specify it explicitly via --targets <col>."
                )
            else:
                result["warnings"].append(
                    f"--targets was not specified; auto-detected candidate target columns "
                    f"{result['auto_detected_targets']}. The skill will prompt the user to confirm."
                )

    # 5. Small-corpus warning — only for pretrain (other modes can be tiny by design).
    if mode == "pretrain" and result["num_rows"] < 100:
        result["warnings"].append(
            f"pretrain corpus is only {result['num_rows']} molecule(s). Pretraining typically "
            f"needs orders of magnitude more — verify this is the intended input."
        )

    result["ok"] = not result["errors"]
    return result


def main(argv: list[str] | None = None) -> int:
    parser = argparse.ArgumentParser(description="Validate a CSV input for a KERMT agent workflow.")
    parser.add_argument("--mode", required=True, choices=["pretrain", "finetune", "inference", "embed"])
    parser.add_argument("--csv", required=True, help="Path to the input CSV")
    parser.add_argument("--targets", nargs="+", default=None,
                        help="(finetune only) target column names. If omitted, the validator auto-detects "
                             "numeric non-smiles columns and reports them as candidates.")
    parser.add_argument("--strict-rdkit", action="store_true",
                        help="Parse every SMILES with RDKit rather than sampling (slow on large CSVs).")
    args = parser.parse_args(argv)

    try:
        result = validate(args.mode, args.csv, args.targets, args.strict_rdkit)
    except Exception as exc:  # noqa: BLE001
        print(traceback.format_exc(), file=sys.stderr)
        print(json.dumps({
            "ok": False,
            "mode": args.mode,
            "csv_path": args.csv,
            "errors": [f"unhandled exception in validator: {type(exc).__name__}: {exc}"],
            "warnings": [],
        }, indent=2))
        return 1

    print(json.dumps(result, indent=2))
    return 0 if result["ok"] else 1


if __name__ == "__main__":
    sys.exit(main())

Requirements and compatibility

Written for: Claude Code, OpenAI Codex

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Needs Python

The author says: Requires docker, nvidia-container-toolkit, and a CUDA-capable NVIDIA GPU. Designed for Claude Code, Codex, and Nemotron.

Security

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  • Large base64-encoded blobs
  • Scripts that your agent may run

This skill includes scripts that your agent may run. Read them before you use it.

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Attribution and licence

Published by
NVIDIA
Publisher
NVIDIA (Official)
Source
NVIDIA/skills · skills/bionemo-kermt-add-cmim-pretrain · commit fce3cca
Licence
Apache License 2.0 (redistribution allowed)
  • LICENSE (added by AutoGineer from LICENSE-APACHE)
  • ATTRIBUTION.md (written by AutoGineer)
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