Returns errors grouped by field as a map of lists of {message_template, opts} tuples.

Messages are not interpolated; templates and their options are preserved for downstream formatting, translation, or logging.

@spec validate_trace_context(Ecto.Changeset.t(), atom()) :: Ecto.Changeset.t()

Validates that trace_context is a flat string-valued map with a bounded number of keys.

The maximum number of keys defaults to 10 and can be overridden via application config:

config :double_entry_ledger, max_trace_context_keys: 20

Rejects nested maps, non-string values, and oversized maps to prevent abuse while remaining vendor-neutral.

Examples

changeset
|> validate_trace_context(:trace_context)