Function: mergeFieldLevel()

function mergeFieldLevel(contributions): [Raw | null, ResolutionLayer | null, Record<string, string>];

Deep-merge spec dicts. Higher-priority layers shadow lower per-field. Returns [mergedDoc, primaryOriginLayer, fieldsByOrigin].

Algorithm: - First pass: find the PRIMARY layer (highest-priority hit). Its metadata + envelope (apiVersion, kind) carry over wholesale. - Second pass: iterate contributions LOWEST → HIGHEST priority, overwriting spec keys in a fresh merged dict. After the loop the highest-priority layer's values win per-field. - Track which layer each FINAL spec field came from so the UI can render spec.persona ← _lib annotations.

Edge cases: - All-null contributions → [null, null, {}]. - Single hit → equivalent to override_full. - Spec missing or non-object → that layer skipped silently.

Parameters

Parameter	Type
contributions	Contribution[]

Returns

[Raw | null, ResolutionLayer | null, Record\<string, string>]