diff --git a/.gitignore b/.gitignore
index 11901563..972062a1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -38,6 +38,7 @@ scripts/venv_unsloth/
 **/venv_wgpu/
 **/*.venv/
 **/venv/
+.venv-science/
 
 # API Keys and credentials (NEVER track in git)
 API KEYS/
diff --git a/docs/optional-science-toolbelt.md b/docs/optional-science-toolbelt.md
new file mode 100644
index 00000000..9899c6b0
--- /dev/null
+++ b/docs/optional-science-toolbelt.md
@@ -0,0 +1,79 @@
+# Optional Science Toolbelt
+
+These tools are optional reference surfaces for math-first work. They are not
+default repo dependencies. Add them to a local environment only when a task
+needs an executable witness, conversion adapter, or independent solver.
+
+The operating rule is simple: Lean remains the source of truth; these tools
+produce receipts, counterexamples, fixtures, and sanity checks.
+
+## Install Manifests
+
+Python packages that are reasonable to install into a task-specific virtual
+environment:
+
+```bash
+uv venv .venv-science
+source .venv-science/bin/activate
+uv pip install -r requirements-optional-science.txt
+```
+
+Equivalent npm convenience commands:
+
+```bash
+npm run setup-science-light
+npm run probe-science
+```
+
+Native command-line tools are listed in:
+
+```text
+system-packages-optional-science.txt
+```
+
+Do not wire these into default CI unless the workflow is explicitly optional or
+the tool is already installed on the runner.
+
+## Probe What Is Available
+
+Use the probe before asking an agent to rely on a domain tool:
+
+```bash
+python3 scripts/probe_science_toolbelt.py
+python3 scripts/probe_science_toolbelt.py --json
+python3 scripts/probe_science_toolbelt.py --json --out shared-data/artifacts/science_toolbelt/probe.json
+```
+
+The probe exits successfully even when optional tools are missing. Missing tools
+are data, not failure.
+
+## Domain Priorities
+
+| Domain | First tools | Use in this stack |
+| --- | --- | --- |
+| Genetics / bioinformatics | Biopython, pysam, samtools, bcftools, minimap2 | Validate FASTA/FASTQ/GenBank/SAM/BAM/VCF fixtures for the genetic-code, Hachimoji, and PIST surfaces. |
+| CFD / PDE | Dedalus, ParaView | Produce spectral PDE reference traces for Burgers/KdV/hyperfluid claims without committing to a heavyweight engineering CFD stack. |
+| Cryptography | liboqs-python, PyCryptodome, galois | Check post-quantum KEM/signature examples, hashes, finite-field arithmetic, and receipt digests. |
+| Chemistry / materials | RDKit, Open Babel | Parse/canonicalize SMILES, compute descriptors, and turn molecular claims into inspectable fixtures. |
+| Formal bridge | Z3, cvc5 | Search bounded counterexamples before spending Lean effort. |
+| Algebra / graph theory | SageMath, GAP, NetworkX, Graphviz | Generate lattice/group/graph witnesses and diagrams for later Lean or receipt promotion. |
+| Compression / signal | zstandard, PyWavelets | Provide compression baselines and spectral/wavelet witnesses for signal-shaping claims. |
+
+## What Not To Do
+
+- Do not add these packages to the default repo environment.
+- Do not treat a solver result as a theorem.
+- Do not commit generated datasets unless they are promoted as small,
+  receipt-bearing evidence.
+- Do not copy implementation code from external tools into the repo.
+
+## Receipt Pattern
+
+For any adapter built on this toolbelt, prefer:
+
+1. Input fixture path.
+2. Tool name and version from `probe_science_toolbelt.py`.
+3. Exact command or Python module call.
+4. Output hash and short human-readable summary.
+5. Link to the Lean theorem, claim registry entry, or distilled doc that the
+   receipt supports.
diff --git a/package.json b/package.json
index fe68c255..a5472dd1 100644
--- a/package.json
+++ b/package.json
@@ -5,7 +5,9 @@
   "scripts": {
     "install-python": "uv python install 3.11.15",
     "setup-cad-env": "cd 5-Applications/text-to-cad && python3.11 -m venv .venv && ./.venv/bin/pip install -r requirements-cad.txt",
-    "verify-cad": "cd 5-Applications/text-to-cad && ./.venv/bin/python -c \"import build123d; import OCP; print('CAD dependencies OK')\""
+    "verify-cad": "cd 5-Applications/text-to-cad && ./.venv/bin/python -c \"import build123d; import OCP; print('CAD dependencies OK')\"",
+    "setup-science-light": "uv venv .venv-science && . .venv-science/bin/activate && uv pip install -r requirements-optional-science.txt",
+    "probe-science": "python3 scripts/probe_science_toolbelt.py"
   },
   "dependencies": {
     "better-sqlite3": "^12.4.1"
diff --git a/requirements-optional-science.txt b/requirements-optional-science.txt
new file mode 100644
index 00000000..867f2166
--- /dev/null
+++ b/requirements-optional-science.txt
@@ -0,0 +1,34 @@
+# Optional science toolbelt for receipt-producing adapters.
+#
+# Install only when a task needs these domains:
+#
+#   uv pip install -r requirements-optional-science.txt
+#
+# These packages are intentionally not part of the default repo setup. They
+# provide reference implementations and data-format adapters for math-first
+# verification receipts.
+
+# Genetics / bioinformatics
+biopython>=1.87
+pysam>=0.24.0
+
+# Chemistry / materials
+rdkit>=2026.3.1
+
+# SMT / formal-methods bridge
+z3-solver>=4.16.0.0
+cvc5>=1.3.4
+
+# Cryptography / finite fields / symbolic checks
+pycryptodome>=3.23.0
+galois>=0.4.6
+
+# Graphs, signal analysis, and compression baselines
+networkx>=3.5
+PyWavelets>=1.9.0
+zstandard>=0.25.0
+
+# Heavy or native-stack options. Keep commented unless a task explicitly needs
+# the solver and the host has the native prerequisites.
+# dedalus>=3.0.5
+# liboqs-python>=0.14.1
diff --git a/scripts/probe_science_toolbelt.py b/scripts/probe_science_toolbelt.py
new file mode 100755
index 00000000..46db5a87
--- /dev/null
+++ b/scripts/probe_science_toolbelt.py
@@ -0,0 +1,242 @@
+#!/usr/bin/env python3
+"""Probe optional science tools without requiring them.
+
+The goal is not to make these tools part of the default stack. The goal is to
+let agents and CI-adjacent smoke checks discover which reference solvers,
+format adapters, and verification backends are available on the current host.
+
+Exit code:
+    0  probe completed; missing optional tools are reported in the payload.
+    2  invalid CLI arguments or unable to write output.
+"""
+from __future__ import annotations
+
+import argparse
+import importlib
+import json
+import shutil
+import subprocess
+import sys
+from dataclasses import asdict, dataclass
+from pathlib import Path
+from typing import Any
+
+
+@dataclass(frozen=True)
+class PythonTool:
+    key: str
+    domain: str
+    module: str
+    purpose: str
+
+
+@dataclass(frozen=True)
+class CommandTool:
+    key: str
+    domain: str
+    command: str
+    purpose: str
+    version_args: tuple[str, ...] = ("--version",)
+
+
+PYTHON_TOOLS: tuple[PythonTool, ...] = (
+    PythonTool(
+        "biopython",
+        "genetics",
+        "Bio",
+        "FASTA/FASTQ/GenBank parsing and sequence manipulation",
+    ),
+    PythonTool("pysam", "genetics", "pysam", "SAM/BAM/CRAM/VCF access from Python"),
+    PythonTool(
+        "rdkit",
+        "chemistry",
+        "rdkit",
+        "SMILES parsing, canonicalization, descriptors, fingerprints",
+    ),
+    PythonTool("z3-solver", "formal-methods", "z3", "SMT checks before Lean proof work"),
+    PythonTool("cvc5", "formal-methods", "cvc5", "SMT checks and model finding"),
+    PythonTool(
+        "pycryptodome",
+        "cryptography",
+        "Crypto",
+        "hash/signature/cipher reference primitives",
+    ),
+    PythonTool("galois", "cryptography", "galois", "finite-field arithmetic"),
+    PythonTool(
+        "networkx",
+        "graph-theory",
+        "networkx",
+        "graph certificates and topology receipts",
+    ),
+    PythonTool(
+        "pywavelets",
+        "signal-processing",
+        "pywt",
+        "wavelet decompositions for spectral receipts",
+    ),
+    PythonTool(
+        "zstandard",
+        "compression",
+        "zstandard",
+        "zstd baseline and dictionary-training adapter",
+    ),
+    PythonTool("dedalus", "cfd-pde", "dedalus", "spectral PDE reference solver"),
+    PythonTool(
+        "liboqs-python",
+        "cryptography",
+        "oqs",
+        "Open Quantum Safe KEM/signature reference adapter",
+    ),
+)
+
+COMMAND_TOOLS: tuple[CommandTool, ...] = (
+    CommandTool(
+        "samtools",
+        "genetics",
+        "samtools",
+        "SAM/BAM/CRAM command-line verification",
+    ),
+    CommandTool("bcftools", "genetics", "bcftools", "VCF/BCF command-line verification"),
+    CommandTool("minimap2", "genetics", "minimap2", "sequence alignment smoke checks"),
+    CommandTool(
+        "sage",
+        "algebra-crypto",
+        "sage",
+        "lattice, group, and symbolic mathematics",
+        ("--version",),
+    ),
+    CommandTool("gap", "algebra", "gap", "computational group-theory checks", ("--version",)),
+    CommandTool("z3", "formal-methods", "z3", "SMT solver CLI", ("--version",)),
+    CommandTool("cvc5", "formal-methods", "cvc5", "SMT solver CLI", ("--version",)),
+    CommandTool("zstd", "compression", "zstd", "compression baseline CLI", ("--version",)),
+    CommandTool("dot", "graph-theory", "dot", "Graphviz graph rendering for witness diagrams", ("-V",)),
+    CommandTool("obabel", "chemistry", "obabel", "Open Babel format conversion", ("-V",)),
+    CommandTool("paraview", "cfd-pde", "paraview", "CFD/PDE visualization frontend", ("--version",)),
+)
+
+
+def _module_version(module: Any) -> str | None:
+    for attr in ("__version__", "VERSION", "version"):
+        value = getattr(module, attr, None)
+        if value is None:
+            continue
+        if callable(value):
+            try:
+                value = value()
+            except Exception:
+                continue
+        return str(value)
+    return None
+
+
+def _probe_python(tool: PythonTool) -> dict[str, Any]:
+    try:
+        module = importlib.import_module(tool.module)
+    except Exception as exc:
+        return {
+            **asdict(tool),
+            "available": False,
+            "error": f"{type(exc).__name__}: {exc}",
+        }
+    return {
+        **asdict(tool),
+        "available": True,
+        "version": _module_version(module),
+        "path": getattr(module, "__file__", None),
+    }
+
+
+def _run_version(path: str, args: tuple[str, ...]) -> str | None:
+    try:
+        result = subprocess.run(
+            [path, *args],
+            capture_output=True,
+            text=True,
+            timeout=5,
+            check=False,
+        )
+    except Exception:
+        return None
+    text = (result.stdout or result.stderr).strip()
+    if not text:
+        return None
+    return text.splitlines()[0]
+
+
+def _probe_command(tool: CommandTool) -> dict[str, Any]:
+    path = shutil.which(tool.command)
+    if path is None:
+        return {
+            **asdict(tool),
+            "available": False,
+        }
+    return {
+        **asdict(tool),
+        "available": True,
+        "path": path,
+        "version": _run_version(path, tool.version_args),
+    }
+
+
+def build_report() -> dict[str, Any]:
+    python_results = [_probe_python(tool) for tool in PYTHON_TOOLS]
+    command_results = [_probe_command(tool) for tool in COMMAND_TOOLS]
+    available = sum(1 for item in python_results + command_results if item["available"])
+    total = len(python_results) + len(command_results)
+    by_domain: dict[str, dict[str, int]] = {}
+    for item in python_results + command_results:
+        bucket = by_domain.setdefault(item["domain"], {"available": 0, "total": 0})
+        bucket["total"] += 1
+        if item["available"]:
+            bucket["available"] += 1
+    return {
+        "schema": "research_stack_optional_science_toolbelt_probe_v1",
+        "summary": {
+            "available": available,
+            "total": total,
+            "by_domain": by_domain,
+        },
+        "python": python_results,
+        "commands": command_results,
+    }
+
+
+def _print_text(report: dict[str, Any]) -> None:
+    summary = report["summary"]
+    print(f"optional science toolbelt: {summary['available']}/{summary['total']} available")
+    for section in ("python", "commands"):
+        print(f"\n{section}:")
+        for item in report[section]:
+            mark = "OK" if item["available"] else "--"
+            version = item.get("version")
+            suffix = f" ({version})" if version else ""
+            print(f"  {mark} {item['key']}: {item['purpose']}{suffix}")
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--json", action="store_true", help="emit JSON instead of text")
+    parser.add_argument("--out", type=Path, help="write the JSON report to this path")
+    args = parser.parse_args(argv)
+
+    report = build_report()
+    if args.out:
+        try:
+            args.out.parent.mkdir(parents=True, exist_ok=True)
+            args.out.write_text(
+                json.dumps(report, indent=2, sort_keys=True) + "\n",
+                encoding="utf-8",
+            )
+        except OSError as exc:
+            print(f"error: failed to write {args.out}: {exc}", file=sys.stderr)
+            return 2
+
+    if args.json:
+        print(json.dumps(report, indent=2, sort_keys=True))
+    else:
+        _print_text(report)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/system-packages-optional-science.txt b/system-packages-optional-science.txt
new file mode 100644
index 00000000..b6d3ca6a
--- /dev/null
+++ b/system-packages-optional-science.txt
@@ -0,0 +1,26 @@
+# Optional system packages for science toolbelt adapters.
+#
+# These are command-line tools or heavyweight native stacks that Python
+# requirements cannot reliably install. Names are Debian/Ubuntu-style package
+# names where available; distro packages vary.
+
+# Genetics / bioinformatics
+samtools
+bcftools
+minimap2
+
+# Formal methods / algebra
+cvc5
+z3
+gap
+sagemath
+
+# Compression and receipt payload baselines
+zstd
+
+# Visualization / data inspection
+graphviz
+paraview
+
+# Chemistry / materials native helpers
+openbabel