static int
__ckpt_delete_one(WT_SESSION_IMPL *session, WT_BLOCK *block, WT_CKPT *ckptbase,
  WT_BLOCK_CKPT *ci, WT_CKPT *ckpt)
{
    WT_BLOCK_CKPT *a, *b;
    WT_CKPT *next_ckpt;
    const char *next_name;

    WT_ASSERT_SPINLOCK_OWNED(session, &block->live_lock);

    /* "From" checkpoint; skip if it applies to a previous object. */
    a = ckpt->bpriv;
    if (a->root_objectid != block->objectid)
        return (0);

    if (WT_VERBOSE_LEVEL_ISSET(session, WT_VERB_CHECKPOINT, WT_VERBOSE_DEBUG_2))
        __wti_ckpt_verbose(session, block, "delete", ckpt->name, ckpt->raw.data, ckpt->raw.size);

    /* Find the next real checkpoint -- the merge target. */
    for (next_ckpt = ckpt + 1;; ++next_ckpt)
        if (!F_ISSET(next_ckpt, WT_CKPT_FAKE))
            break;

    b = F_ISSET(next_ckpt, WT_CKPT_ADD) ? &block->live : next_ckpt->bpriv;
    next_name = next_ckpt->name != NULL ? next_ckpt->name : "live";

    /* Free the "from" root page into its own discard list. */
    if (a->root_offset != WT_BLOCK_INVALID_OFFSET)
        WT_RET_MSG_CHK(session,
          __wti_block_insert_ext(session, block, &a->discard, a->root_offset, a->root_size),
          "inserting root page into discard list for deleted checkpoint %s", ckpt->name);

    /* Free the blocks holding the "from" extent lists. */
    WT_RET_MSG_CHK(session, __ckpt_extlist_fblocks(session, block, &a->alloc),
      "freeing alloc extent list blocks for deleted checkpoint %s", ckpt->name);
    WT_RET_MSG_CHK(session, __ckpt_extlist_fblocks(session, block, &a->avail),
      "freeing avail extent list blocks for deleted checkpoint %s", ckpt->name);
    WT_RET_MSG_CHK(session, __ckpt_extlist_fblocks(session, block, &a->discard),
      "freeing discard extent list blocks for deleted checkpoint %s", ckpt->name);

    /* Roll the "from" alloc/discard lists into the "to" checkpoint. */
    if (a->alloc.entries != 0)
        WT_RET_MSG_CHK(session, __wti_block_extlist_merge(session, block, &a->alloc, &b->alloc),
          "merging alloc extent list from deleted checkpoint %s", ckpt->name);
    if (a->discard.entries != 0)
        WT_RET_MSG_CHK(session, __wti_block_extlist_merge(session, block, &a->discard, &b->discard),
          "merging discard extent list from deleted checkpoint %s", ckpt->name);

    /* If the target is also being deleted, leave it for the next iteration to absorb. */
    if (F_ISSET(next_ckpt, WT_CKPT_DELETE))
        return (0);

    /* Move overlapping ranges in the target into the live avail list for re-use. */
    WT_RET_MSG_CHK(session, __wti_block_extlist_overlap(session, block, b),
      "finding reusable blocks in checkpoint %s", next_name);

    if (F_ISSET(next_ckpt, WT_CKPT_ADD)) {
        WT_RET_MSG_CHK(session, __ckpt_live_blkmods(session, ckptbase, ci, block, false),
          "clearing live block modifications after merging into %s", next_name);
        return (0);
    }

    /* Target is a real on-disk checkpoint: free its old extent-list blocks and flag for rewrite. */
    WT_RET_MSG_CHK(session, __ckpt_extlist_fblocks(session, block, &b->alloc),
      "freeing alloc extent list blocks for updated checkpoint %s", next_name);
    WT_RET_MSG_CHK(session, __ckpt_extlist_fblocks(session, block, &b->discard),
      "freeing discard extent list blocks for updated checkpoint %s", next_name);
    F_SET(next_ckpt, WT_CKPT_UPDATE);

    return (0);
}

static int
__ckpt_delete_and_merge(WT_SESSION_IMPL *session, WT_BLOCK *block, WT_CKPT *ckptbase,
  WT_BLOCK_CKPT *ci)
{
    WT_CKPT *ckpt;

    WT_ASSERT_SPINLOCK_OWNED(session, &block->live_lock);

    WT_CKPT_FOREACH (ckptbase, ckpt)
        if (!F_ISSET(ckpt, WT_CKPT_FAKE) && F_ISSET(ckpt, WT_CKPT_DELETE))
            WT_RET(__ckpt_delete_one(session, block, ckptbase, ci, ckpt));

    WT_CKPT_FOREACH (ckptbase, ckpt)
        if (F_ISSET(ckpt, WT_CKPT_UPDATE))
            WT_RET_MSG_CHK(session, __ckpt_update(session, block, ckptbase, ckpt, ckpt->bpriv),
              "updating checkpoint %s after deletion merge", ckpt->name);
    return (0);
}