ID

R218

Status

Backlog

Bucket

architecture

Created

2026-05-21

Updated

2026-05-21

Carry inference provenance on ParamSource.Arg so resolved bindings audit cleanly

R214’s ServiceCatalog.inferBindingsByType mutates argByJavaName silently between the override-typo check and the per-parameter loop. The resulting ParamSource.Arg(extraction, path) is structurally identical regardless of whether the binding came from an explicit argMapping, a same-name identity match, the arity-unique inference branch, or the type-unique inference branch. The resolved-coordinate report and any future LSP "where did this binding come from?" surface can’t tell them apart. The principles-architect review (round 1, finding 4) flagged this as a "load-bearing invariant doesn’t have an emit-time witness" gap, citing the typed-rejection / auditable-resolution narrative the project rests on.

This is the same shape R215 addresses for input fields. R215 introduces InputField.UnboundField precisely so the classifier’s structural answer is visible by type rather than re-derived; consumers switch on the variant exhaustively. The R214 analogue: split ParamSource.Arg into a small sealed taxonomy carrying the binding’s provenance (Explicit for argMapping overrides, IdentityNameMatch for the default same-name binding, Inferred.Arity and Inferred.Type for the two R214 branches). Consumers either treat them uniformly (most emitters) or switch exhaustively when provenance matters (resolved-coordinate report, LSP "go to binding source", validators that want to refuse inferred bindings in strict modes).

Scope notes for Spec:

  • Shape. Sealed sub-taxonomy on ParamSource.Arg, vs. an enum axis carried alongside extraction / path, vs. a wrapper record InferredArg(Arg inner, InferenceKind kind) implements ParamSource. Each has different exhaustiveness consequences for the downstream switch surface (FetcherEmitter, ServiceProducerPipeline, RecordBindingResolver).

  • Visibility. Where does provenance render? Resolved-coordinate report (definitely); LSP hover on the Java parameter (likely); a build-time warning when an inferred binding survives into emission (open ; turns the silent rebind into a noisy one, which authors can grep but might find chatty).

  • Strict mode. Should a build-time flag let authors disable inference entirely (only argMapping and identity name match allowed)? Useful for codebases that want zero implicit behavior; cheap to add once provenance is typed.

Files in play: model/ParamSource.java, ServiceCatalog.java (inferBindingsByType, both reflect methods), every downstream switch on ParamSource (compiler exhaustiveness check is the safety net), and the resolved-coordinate report renderer.

Related: R214 (sibling, shipped with silent provenance; this item adds the audit axis), R215 (same principle applied to input field classification ; the variant identity records the structural fact once).