Coverage-guided composition generation

ChemWorld generates a finite qualification suite from a declared coverage target. The generator is not an enumerator of all possible worlds and its report explicitly records that no exhaustive-coverage claim is made.

Three coverage layers

Layer	Qualification method	Reported denominator
Discrete authoring axes	deterministic pairwise covering rows	all declared value pairs across every pair of axes
Continuous workflow axes	seeded Latin hypercube samples	one stratum per sample and continuous axis
Ordered workflow interactions	contiguous operation subsequences at the declared depth	union of declared workflow interactions

The emitted case count is the largest of the three finite requirements: pairwise rows, continuous samples and workflow templates. Shorter designs are cycled so every required row, sample and workflow appears at least once. The generator does not form their Cartesian product.

Public Python entry point

import chemworld

suite = chemworld.generate_world_composition_coverage(
    base_request,
    suite_id="reaction-assay-coverage",
    discrete_axes=(
        chemworld.DiscreteCoverageAxis(
            axis_id="world_split",
            bindings=("world_split",),
            values=("public-dev", "public-test"),
        ),
        chemworld.DiscreteCoverageAxis(
            axis_id="instrument_profile",
            bindings=(
                "components.observation.parameters.instruments",
                "task.instruments",
            ),
            values=(
                ["hplc", "final_assay"],
                ["gc", "final_assay"],
                ["uvvis", "final_assay"],
            ),
        ),
    ),
    continuous_axes=(
        chemworld.ContinuousCoverageAxis(
            axis_id="temperature_K",
            lower=310.0,
            upper=390.0,
            unit="K",
        ),
    ),
    workflows=(
        chemworld.OrderedWorkflowTemplate(
            workflow_id="heat-then-assay",
            actions=(
                {"operation": "add_solvent", "volume_L": 0.03, "solvent": 2},
                {"operation": "add_reagent", "amount_mol": 0.01},
                {
                    "operation": "heat",
                    "target_temperature_K": {
                        "coverage_axis": "temperature_K"
                    },
                    "duration_s": 600.0,
                    "stirring_speed_rpm": 600.0,
                },
                {"operation": "terminate"},
                {"operation": "measure", "instrument": "final_assay"},
            ),
        ),
    ),
    target=chemworld.CompositionCoverageTarget(
        discrete_strength=2,
        continuous_samples=8,
        ordered_interaction_depth=2,
        seed=0,
    ),
)

Discrete bindings may target world_split, task fields, nested task resource or evaluation fields, and component parameters. One discrete value may bind multiple paths so an instrument profile can update both the observation component and task surface atomically.

Continuous values enter workflows through an exact {"coverage_axis": "axis_id"} placeholder. Every declared continuous axis must appear in at least one workflow; unused coordinates are rejected rather than reported as covered.

Fail-closed behavior

Every generated request is compiled through the same compatibility checker as an authored world. Every materialized action must belong to the compiled operation surface and pass the public action schema. If any case fails, generation raises WorldCompositionCoverageError with a readable report containing the exact attempted denominator and every failed case; a partial suite is not returned as successful output.

For a successful suite, suite.report contains:

• the frozen target and generated case count;
• exact required and covered counts for all three coverage layers;
• the number of pairwise rows, continuous samples and workflows;
• attempted, successful and failed case counts;
• an explicit exhaustive_enumeration_claim: false boundary; and
• a zero failure count with an empty failure list.

Coverage construction is therefore distinct from physical or transactional qualification. The suite says which cases and ordered interactions were selected; later qualification must execute them and report its own denominators and failures.