Enumerate prompt input and variable dependencies

docs/internal/sources.md

@@ -57,6 +57,15 @@ captured presence state. Runtime rendering still checks request variables and
 input helpers. The [prompt adapter tests](../../internal/configuration/prompts_test.go)
 cover resource origins, context containment, capture, and selection.
 
+The `internal/prompt` requirement walker uses the captured parse trees and
+declaration metadata without executing templates or reading artifacts. It
+collects literal `input` names, direct root caller keys, and literal-key
+`index` lookups. Branch-body references are conservatively conditional until
+condition analysis is applied; invoked named templates are scanned
+conservatively, and dependency-bearing range scopes make discovery incomplete.
+Uncalled definitions and bypassed session templates are not traversed. This
+internal walker does not change rendering behavior.
+
 ## Profiles And Built-Ins
 
 `internal/catalog` selects the released keyed OpenRouter and Rakestrawhome