@stralos-co-nz/calculators (from 1.9.0, packages/calculators/src/calculatorInputLinks.ts in stralos-domain) defines the contract for linking a trench, pit, or volume calculator’s length or area field to takeoff. The resolved value is written into the calculator’s config (config.length, config.lengthM, or config.areaM2), so the engine and every config type are unchanged. Calculator input links are stored in estimate_calculators.input_links.
A calculator input takes takeoff sources only: a measurement’s total, or the sum of one or more of its tag subtotals (from calculators 1.14.0). Tag subtotals come from a Multi-segment or tagged Multi-line and are in metres, so only a length field can take one. A link that holds a measurement’s total and one of its own tag subtotals is refused with takeoff_overlap, as for any other target. The resolution graph must stay acyclic: takeoff → calculator inputs → build-up lines → work items.
Linkable fields
pit.lengthM is linkable from calculators 1.17.0; other pit fields are not. calculatorLinkableFieldUnit(field) returns "metre" or "square_metre", the unit passed as workItemUnit when resolving the link.
calculatorLinkableFieldApplies(field, calculator) returns whether the field exists on the calculator as currently configured. A mode switch that makes a linked field inapplicable orphans its link and the server raises a 409 calculator_source_removed.
CalculatorInputLinksV1
fields is a QuantityLinkV1 descriptor validated with quantityLinkTargetIssues(link, "calculatorInput"): takeoff sources only, including tag subtotals. A non-takeoff source raises target_source_kind. The unit check happens at resolution, not here: a tag subtotal on volume.areaM2 resolves with a unit mismatch, which api-estimate refuses on write as 422 quantity_link_unit. Resolution uses resolveQuantityLink with calculatorLinkableFieldUnit(field) as workItemUnit.
Validation
@stralos-co-nz/calculators has no whole-value validator for input_links (calculatorInputLinksIssues was removed in calculators 2.0.0). api-estimate checks the top-level shape with its own strict schema, calculatorInputLinksSchema in src/quantityLink/calculatorInputs.ts: v must be 1, and fields may hold only keys from CALCULATOR_LINKABLE_FIELDS, each a QuantityLinkV1. Each changed link is then checked with quantityLinkTargetIssues(link, "calculatorInput").
Whether a field applies to the calculator’s current mode is calculatorLinkableFieldApplies, which needs the config and is the host’s check.