Reference

Variable Resolution Reference

Variable resolution is where rototo turns a named runtime configuration request into one selected value. The app supplies context, rototo evaluates rules, and the selected value comes from the workspace version currently loaded by the app.

Input

Variable resolution needs:

a loaded, lint-clean workspace;
a variable id;
a JSON object context.

CLI:

rototo resolve account-config \
  --variable account-limits \
  --context account.plan=enterprise

SDK:

let resolution = workspace
    .resolve_variable("account-limits", &context)
    .await?;

Rule Evaluation

Variable rules are evaluated in file order:

[resolve]
default = "growth"

[[resolve.rule]]
qualifier = "enterprise-account"
value = "enterprise"

[[resolve.rule]]
qualifier = "paid-account"
value = "paid"

Resolution follows this path:

Resolve the first rule's qualifier.
If it is true, select that rule's value and stop.
If it is false, continue to the next rule.
If no rule matches, select the default value.

The default is always the fallback. It is not evaluated as a qualifier.

Value Selection

For primitive variables, selected values come from [values].

For resource-backed variables, selected values come from resources/<resource-id>-objects/*.toml and are validated against the resource schema.

The resolution result includes both:

value_key: the selected key;
value: the selected JSON value.

Shadowed Rules

If two rules use the same qualifier, the later rule can never win. Rototo reports rototo/variable-rule-shadowed.

If a rule selects the same value as the default, rototo reports rototo/variable-rule-selects-default-value.

These rules are warnings about operational clarity. A reader should not have to guess whether a later rule is meaningful.

Trace Shape

CLI --json returns a variable trace:

{
  "resolution": {
    "id": "account-limits",
    "value_key": "enterprise",
    "value": {
      "projects": 100,
      "members": 250
    }
  },
  "default_value": "growth",
  "rules": [
    {
      "index": 0,
      "qualifier": "enterprise-account",
      "value": "enterprise",
      "matched": true
    }
  ],
  "qualifier_traces": [
    {
      "id": "enterprise-account",
      "value": true,
      "predicates": []
    }
  ]
}

qualifier_traces contains the qualifiers evaluated while resolving the variable. Use it to explain why the selected value won.

Context Validation

If schemas/context.schema.json exists, rototo validates context before resolution. SDK callers can disable that with ResolveOptions, but the default is validation on.

Multiple Variables

rototo resolve --variables resolves all variables in workspace order with the same context. The SDK free function rototo::resolve_variables does the same for a local workspace root.

If any variable resolution fails, the command or API call fails. Use targeted selectors when debugging a context that is not meant to satisfy every variable.