A pair returned by the GroupBy was just reported as duplicated, so a row
must exist. Continuing on !has would let the delete loop drop every row
for that pair without re-inserting one, silently losing positions. Abort
the migration instead.
A task could end up with more than one task_positions row for the same
(task_id, project_view_id): rapid/concurrent creation raced the
check-then-insert paths, and the create path could insert a position that
a triggered RecalculateTaskPositions had already persisted for the new
task. The table had no unique constraint, so the duplicates were stored
silently (#2844).
In the table view this made the LEFT JOIN on task_positions emit the task
twice; getTasksForProjects enriched only the map entry, so the duplicate
slice row kept an empty identifier and rendered as "#N" instead of
"PREFIX-N" (#2725).
- Add a unique index on task_positions(task_id, project_view_id) via a
dedup migration (mirrors the task_buckets fix in 20250624092830) plus the
unique(task_view) struct tag so fresh installs get it too.
- Harden the create path: only queue a position insert when one does not
already exist for the task+view, and dedupe within the batch.
- Dedupe the task slice returned by getTasksForProjects by id, returning
the enriched entry, so duplicate position rows can never surface a task
twice or with a missing identifier.
Fixes#2844Fixes#2725
kolaente