Rolling back is now non-destructive: instead of truncating the future,
it restores the target checkpoint's snapshot and points
Game.rollback_head_checkpoint_id at it. Later checkpoints/events are
kept and rendered greyed; rolling forward to one redoes the rollback
(same endpoint). The abandoned future is discarded only when a new
action is taken from a rolled-back state -- maintain_rollback_history
truncates it, clears the head, and bumps rollback_timeline_version,
now the sole trigger for the frontend log reset.
- Game.rollback_head_checkpoint_id (nullable; in SNAPSHOT_EXCLUDE) +
Alembic migration.
- crud_rollback: rollback_to_checkpoint sets the head (None at latest);
_discard_future + head-clear + version-bump moved into the next scene
action's capture.
- EventLog.svelte: greyed future, redo (forward) affordance, a "rolled
back" banner; dropped the now-misleading destructive confirm.
- Tests rewritten for head-pointer semantics (+ redo, action-after-
rollback truncation, scene-end head clear); HTTP integration test
extended to drive the full cycle over the wire.
Verified end-to-end in a browser: rollback greys the future and reverts
live state (captaincy/ranks), redo restores it, no errors.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Tim McCarthy
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