So by Chronicles, I mean things like the Gesta Francorum, one of the primary sources of the history of the 1st Crusade.
In my 1st Crusade Saga, the PC has decided that one of his Covenants Specailists will have been a Chronicler to write a history. This would have started in mid 1096, and now in later in fall 1098 the major journey and battles are all complete. Mechanically, this is not necessarily a traditional tractatus or summae on a known Area Lore or other ability.
Clearly, in my opinion, the base rules for Quality still apply... But how would it be treated by someone who studies it? Does the number of Area Lores it applies to depend on the number of seasons it takes to write? A day by day journey for two years in this case would be 9 seasons worth of writing. Is this a Summae? But on what? Does it need to be recompiled into a new text?
My gut instinct: treat it as a summa and then extra books might be tractatii on the same (or different) topic, like some of the examples of A&A.
So book 1 might be an Area Lore (Levant) summa (since it is the main focus), book 2 is a tractatus in Area Lore (Southern Italy) as it discusses the stuff that happened there, book 3 having a different focus might be a tractatus on Leadership (for example, as it goes through the battles and what the leaders did/said).
I would follow the standard rules for quality tractatus or summa.
It might be written over 9 seasons, but it's not 9 seasons of full time work, since the writer was active with other things in the process.
I don't see why one would need to recompile.
You can start your Chronicle as a standard Summa on your Area Lore. But for it to become a real Chronicle, you should continue it afterwards with monthly entries taking a day or two to write.
Take some inspiration from Covenants p.90 Correspondences: a minimum of 48 monthly entries is required, and they are read as Tractatus (one per 48 entries) of a quality of your Communication + Area Lore.
A Quality of Communication + 6 might be too much for an average Chronicler - but if you really know and follow up on what happens in the Area, you might also exceed the +6. Gossip and Social Contacts might provide some little boni to Quality.
Might it be worth thinking about how the book is intended to be used? Is it meant to be a book that can be studied once, or is it meant to be consulted again and again?
My gut instinct with this one (given that it will be a relatively short work, and given my knowledge of the source on which you're modelling it), would be to make it function as a set of tractati on a number of subjects (Area Lore, History, Theology, possibly some supernatural lores). Thus it would be possible to study it multiple times, but each ability only once.
Then as the chronicle gets expanded in future years, you could add extra tractati covering whatever lores seem appropriate as the saga progresses.
