"You can correct the record going forward. You can never reach back and change what you knew then."
The Hardest Rule
Everything in this track converges on one rule that is easy to state and hard to hold: a retrospective must never rewrite what was known at the time. When you look back at a trip and want to tidy it — fix a place name, move a note to the right day, correct a plan that didn't survive the weather — the temptation is to edit history so it reads cleanly. Waystone forbids the edit and offers a different move: append a correction, never overwrite the original. The past stays exactly as it was; the correction is a new fact layered on top, stamped with when it was made.
Append, Don't Overwrite
This shows up concretely in how breadcrumbs are corrected. A breadcrumb's original capture record — when and where it was submitted — is immutable. Want to fix its text or its place? That is an edit revision that folds into the live view while leaving the capture-time record intact. Want to move it to a different day because you filed it under the wrong date? That is an append-only revision of its schedule date; its identity, capture time, media, and locations all stay unchanged. And a tombstoned breadcrumb cannot be revised back into existence — deletion is honest and final, not quietly undone. Correction is always additive, never destructive.
Why This Protects the Whole Engine
The reason is the one this track has circled the whole way: the engine's value is that it remembers what you knew at the time, including the wrong guesses, the abandoned plans, and the notes you filed on the wrong day. A retrospective that rewrites those away leaves a record that is neater and less true — and less true is exactly the failure a memory engine cannot afford. The clean-looking history is a liability if it was purchased by deleting what actually happened. Append-only correction is how Waystone stays both accurate and honest: accurate now, honest about then.