FAIR Simulation Packager

Goal

Build a minimal reproducibility manifest for materials simulation results so another person or agent can understand what was run, with which inputs, and how outputs should be interpreted.

Requirements

• Python 3.10+
• No external dependencies
• Works on Linux, macOS, and Windows

Inputs to Gather

Decision Guidance

• Always include input files, output files, code version, and units.
• Include hashes for every file that exists locally.
• Include structure identifiers when using Materials Project, NOMAD, OPTIMADE, CIF, POSCAR, or internal database records.
• Record missing files as warnings instead of silently dropping them.

Script Outputs

scripts/fair_packager.py --json prints an envelope with two top-level keys:

• inputs: the parsed CLI arguments echoed back (note: inputs.inputs is the raw

comma-separated string passed via --inputs, not the per-file records).

• results: contains a single key manifest.

results.manifest contains these fields:

• project_name, engine, engine_version, structure_id, units
• file_inventory with inputs and outputs, each a list of per-file records

(path, exists, and when the file exists, size_bytes and sha256)

• missing_files: paths that do not exist on disk
• provenance (working_directory, manifest_schema)
• fair_checks: has_inputs, has_outputs, has_units, has_engine_version, and

has_hashes_for_existing_files (true/false, or null when no files exist so the check is not applicable)

• recommended_next_steps

Parse fields at results.manifest.<field>. When --out PATH is given, only the bare manifest object (not the inputs/results envelope) is written to PATH.

Workflow

python3 skills/data-management/fair-simulation-packager/scripts/fair_packager.py \
  --project-name al-cu-diffusion \
  --engine LAMMPS \
  --inputs in.lammps,data.lmp \
  --outputs log.lammps,traj.dump \
  --units energy=eV,length=angstrom,time=ps \
  --structure-id local:alcu-cell-001 \
  --json

Use --out manifest.json only when the user wants a manifest file written.

Error Handling

Missing files are reported in missing_files (exit code 0). Invalid input stops with exit code 2: malformed unit entries, fields containing control characters, fields longer than 4096 characters, more than 1000 input or output entries, or a file larger than 500 MB. Note that ordinary file paths — including absolute paths and paths containing .. — are accepted and inventoried; the tool reads file contents only to compute metadata and SHA-256 hashes.

Limitations

This skill creates a metadata manifest. It does not upload to NOMAD, Materials Project, or an OPTIMADE provider.

Verification checklist

• [ ] Confirmed fair_checks.has_hashes_for_existing_files is true (not null or false); a null means no listed file existed on disk, so re-run from the directory where the files actually live before trusting the manifest.
• [ ] Reviewed missing_files and confirmed it is empty, or recorded an explicit reason for each entry — every missing path means an input/output was named but not hashed, so the bundle is not reproducible as-is.
• [ ] Spot-checked at least one sha256 in results.manifest.file_inventory against an independent sha256sum/Get-FileHash of the same file to confirm the recorded digest matches the bytes on disk.
• [ ] Confirmed engine_version is a real version string and not the default "unknown"; pass --engine-version so the bundle records the exact code build.
• [ ] Verified units is non-empty and every reported quantity (energy, length, time, etc.) has an entry, so downstream consumers do not have to guess the unit system.
• [ ] Confirmed structure_id is populated when a Materials Project / NOMAD / OPTIMADE / CIF / POSCAR structure was used, so the structure identity is recoverable.
• [ ] When --out PATH was used, opened PATH and confirmed it holds the bare manifest object (not the inputs/results envelope) and that no unintended path outside the working directory was written.

Common pitfalls & rationalizations

Security

Input Validation

• --project-name and --engine are required and must be non-empty after stripping

whitespace; an empty value stops with exit code 2.

• --project-name, --engine, --structure-id (when given), and every file path are

checked for control characters (ord < 32) and a 4096-character maximum length; either condition stops with exit code 2.

• --inputs and --outputs are split on commas and capped at 1000 entries each; more

entries stop with exit code 2.

• --units entries must be key=value; both the key and the value must match the

allowlist ^[A-Za-z0-9_.:/@+-]+$. A missing = or a non-matching key/value stops with exit code 2.

• There are no numeric inputs, so no finite/positive numeric checks are performed.

File Access

• The script reads each existing input/output file in 1 MB chunks to compute its

size_bytes and SHA-256 hash; files that do not exist are recorded but not read.

• A file larger than 500 MB stops with exit code 2 before it is hashed.
• The script writes no files unless --out PATH is given, in which case it writes exactly

one file (the bare manifest JSON) to that path; otherwise all output goes to stdout.

• Paths are not sandboxed: absolute paths and paths containing .. are accepted for both

the inventoried files and --out. If --out points outside the working directory, the file is written there as requested.

Tool Restrictions

• Bash is used to run the bundled scripts/fair_packager.py.
• Read, Write, Grep, and Glob are declared so the skill can inspect the working

directory and read or write manifest/metadata files when guiding the user; they are not invoked by the script itself, which performs all of its own file I/O directly.

Safety Measures

• No eval, exec, os.system, or subprocess calls; the script does not shell out and

parses arguments with argparse.

• Output is emitted as JSON via json.dumps (or a short plain-text summary without

--json).

• DoS caps bound resource use: 500 MB per file, 1000 entries per input/output list, and

4096 characters per field.

References

• See references/fair_manifest.md for recommended manifest fields.

Version History

• 1.2.0: Made eval cases discriminating by pinning the script's exact --json

output (per-file sha256/size_bytes, units, structure_id, engine_version, missing_files, and the tri-state has_hashes_for_existing_files) against committed evals/files/ fixtures.

• 1.1.0: Documented the real --json envelope shape; made

has_hashes_for_existing_files tri-state (null when no files exist); added entry-count (1000) and field-length (4096) caps; corrected the Error Handling and Security wording to describe actual path behavior.

• 1.0.0: Initial FAIR simulation packaging skill.