`place_action` used to read `depth` from `index`, so the fixture's retry
attempts all landed on the turn's own depth and formed one sibling group.
Now that depth comes from the head, each attempt moved the head one step
and every retry became a turn of its own. The fixture's own check caught
it: a coordinate holding a single superseded attempt has no live row, and
that turn disappears from the story.
The attempts at one turn share that turn's coordinate, so only the first
one goes through `place_action` and the rest copy its placement. This is
what `attempts.add_attempt` does. The fixture cannot call it directly,
because it makes the newest attempt live and the fixture needs a live
attempt that is often not the newest.
Also drop the `variant_index` and `variant_count` arguments, which raise
`TypeError` now, and read the two mark positions from a helper instead of
from the adventure columns migrations 72 and 73 removed.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YFQY6WgaE3JaX3dXkxLynV
