Canon Debt: The One-Page Log That Stops Your Campaign From Contradicting Itself

Session notes are a diary. Canon is a different document — here's the one-page format that stops your campaign from contradicting itself six months from now.

Session 34. A player asks if the blacksmith in Thornwick ever paid off the debt to the Ashgate family — the one you established, off-hand, back in session 9. You have no idea. You improvise. Three sessions later, someone finds your session 9 notes and you've just contradicted yourself in front of the whole table.

That's canon debt, and it accumulates the same way real debt does: quietly, in small unpaid decisions, until the interest comes due at the worst possible moment.

Session notes don't fix this. Session notes are a diary — a record of what happened, in order, written for a future you who has to read forty documents to answer one question. Canon debt needs the opposite: a record of what's true, stripped of narrative, sorted by subject, short enough to actually check before you open your mouth.

Build a canon log, not more notes

A canon log is a separate, short list of established facts — the things your table can no longer unsay without a retcon conversation. It is not a summary of the session. It is not your prep. It is the residue left after a session ends: the stuff that's now permanently true about the world.

The rule that makes it work: one line per fact, and it only earns a line if undoing it would mean telling your players "actually, that didn't happen." A player's backstory detail you improvised and they loved? That's canon now — log it. An NPC's name you made up under pressure and will never reference again? Skip it. That's not debt, that's noise.

Format each entry the same way, every time — session number, category, then the fact itself:

09 — Faction — The Ashgate family holds Thornwick's blacksmith debt; unpaid as of last mention.

21 — NPC — Captain Reyes lost her left eye at Kelmouth, not in the war — she lies about which.

27 — Timeline — The bridge at Dunmoor collapsed the same night as the harvest festival.

Four categories cover almost everything: NPC, Faction, Location, Timeline. If a fact doesn't fit one of those, it's probably prep dressed up as canon — leave it out.

Update it after the session, not during

Trying to log facts live while you're also running combat and doing three voices is how canon logs die in week two. Give yourself fifteen minutes after the table clears: skim what happened, pull out anything that crossed from "maybe" to "true," and add the line. Fifteen minutes against forty documents of notes is not a close fight.

Why this is easier if your notes already live in one place

The whole point falls apart if the canon log becomes yet another tab competing with your session notes, your NPC list, and your faction map. If GameMasterCraft is already where your campaigns, NPCs, factions, locations, and lore live, the canon log isn't a new habit — it's a new view on stuff you're already tracking, one search away instead of one memory away. The discipline isn't the tool, though. It's the one-line, established-facts-only rule. Bring that rule to a blank doc and it still works.

Six months from now, a player is going to ask you something you said once, off-hand, in a session you barely remember. The canon log is the difference between "let me check" and just making something up and hoping nobody has the receipts.

Canon Debt: The One-Page Log That Stops Your Campaign From Contradicting Itself