@spec age_line(:error | Memory.t() | term(), DateTime.t()) :: binary()

Returns an "Age" line for a memory.

Examples:

• "Age: unknown (missing timestamps)"
• "Age: 312 days (updated 12 days ago)"

Notes:

• Uses updated_at if present; otherwise uses inserted_at.
• Uses now for deterministic testing.
• If the first argument is :error or any non-struct value (e.g. a parse error), this will return "Age: unknown (missing timestamps)".

@spec parse_ts(nil | iso8601()) :: {:ok, DateTime.t()} | :error

Parse an ISO8601 timestamp string into a DateTime.

Returns {:ok, dt} or :error.

@spec warning_line(:error | Memory.t() | term(), DateTime.t(), keyword()) ::
  binary() | nil

Returns an optional warning line based on how long ago the memory was updated.

• If updated_at is missing/unparseable, returns nil.
• If updated_days >= strong_days, returns a strong warning.
• Else if updated_days >= mild_days, returns a mild warning.
• Else returns nil.

This is intended as a gentle prompt to check for cobwebs.

If the first argument is :error or any non-struct value, this function will return nil (no warning).