Not a blog. The actual specifications the system was built from, including the decisions that turned out wrong and the tests that caught them.
ASC 606 contracts and recognition, the close lock as a posting guard, multi-entity consolidation, continuous agents. Includes the deferred-revenue roll-forward bug: the first implementation moved the whole recognised amount through deferred revenue and reported a difference that did not exist. A test caught it.
Why state is never serialised out, and why the log records what was asked for rather than what resulted. One code path applies changes and restores them, so a restored ledger is arrived at the way the original was.
The orchestrator, the tool layer and verifyNarration — why the LLM is never the source of financial truth, and what happens to an answer that breaks that rule.
How tax questions are answered from a curated corpus with citations and verification dates, and why answering them from model memory is not allowed.
Both are available right now, with no sign-up.