If the target date file does not exist, create it with the date heading and the new activity block.
Include ### Goal and ### Reasoning when creating any new activity block.
If the target date file exists, append the new activity in the correct format without rewriting unaffected activities.
Do not duplicate an activity that is clearly the same calendar object under a different wording.
Edit
Read the current live day file first.
When revising an activity materially, update ### Goal and ### Reasoning too if the training purpose or the planning logic changed.
Replace stale metadata or section content in place.
Keep the same Id when the activity is still the same object after revision.
If the activity changed so much that it is no longer the same object, delete the obsolete block and create a new one with a new title and Id.
Delete
Remove only the activity blocks that are no longer part of the current plan.
Do not leave contradictory remnants behind.
Do not leave an active day file empty. If all activities are removed and the day still needs an active planning object, replace the file content with an explicit rest-day object.
Move
Read both the source and destination live day files first when both exist.
Remove the activity from the source date.
Add the activity to the destination date using the destination file date in the Id.
Preserve the activity content unless the move instruction also changes the session itself.
If the source file becomes empty after the move, either archive it or replace it with an explicit rest-day object, depending on the requested plan state.
Rewrite a day
Use a full rewrite only when the day changed materially and piecemeal edits would leave stale or misleading content.
Preserve the top-level date heading.
Replace the full live day content with the new current planned state.
Archive
Archive only when the file should be retained for reference but removed from the active calendar set.
Move the file from athlete/calendar/ to athlete/calendar/archives/.
Preserve the file content structure.
If a same-name file already exists in archives/, rename the moved file with an incremented suffix such as YYYY-MM-DD-1.md, YYYY-MM-DD-2.md, and so on.
Archived files are reference artifacts and should be ignored by default in normal calendar reads and writes.
