(dolt branches) interrupting gen push before assets finish uploading breaks remote

[bobvh]

Where

src/commands/remote/operations.rs, execute_push() (~line 462-499)

What

execute_push() pushes the Dolt metadata commit first (run_graph_transfer(...push(&graph, ...)...)), then uploads the referenced asset bytes second (transfer_assets(..., RemoteOperation::Push, ...)). These are two separate, non-atomic network operations with no rollback between them.

Repro

#!/usr/bin/env bash
set -euo pipefail
gen=/path/to/gen/target/debug/gen   # adjust: native debug build of the `gen` CLI
remote_url=http://localhost:5800/api/repos/<namespace>/<repo>   # any writable GenHub remote

# 1. Clone and stage a new sample so the next push has a new asset to upload.
tmp=$(mktemp -d) && cd "$tmp"
"$gen" clone "$remote_url"
cd */  # enter the cloned repo directory
printf '>killtest\nGGGGTTTTCCCCAAAA\n' > /tmp/killtest.fasta
"$gen" import fasta /tmp/killtest.fasta --sample killtest

# 2. In the `gen` source tree, temporarily add a delay between the metadata
#    push and the asset transfer in execute_push() (src/commands/remote/operations.rs),
#    right after the `run_graph_transfer(..., RemoteOperation::Push, ...)` call
#    and before the `transfer_assets(...)` call:
#
#        eprintln!("DEBUGREPRO: metadata push done, sleeping before asset transfer");
#        std::thread::sleep(std::time::Duration::from_secs(5));
#
#    then `cargo build --bin gen` in the gen repo.

# 3. Background the push, wait for the debug marker, then kill mid-sleep
#    (i.e. after the Dolt metadata push has landed remotely, before the asset
#    upload starts):
nohup "$gen" push > /tmp/push_kill_test.log 2>&1 &
push_pid=$!
sleep 3   # tune so /tmp/push_kill_test.log contains the DEBUGREPRO line first
grep -q DEBUGREPRO /tmp/push_kill_test.log   # confirms we're mid-sleep, not still in the metadata push
kill -9 "$push_pid"

# 4. Any fresh clone of the same branch now fails permanently:
tmp2=$(mktemp -d) && cd "$tmp2"
"$gen" clone "$remote_url"
# -> Error: Asset <hash> download failed with HTTP 404

# 5. Revert the temporary sleep/eprintln (git checkout -- src/commands/remote/operations.rs
#    or manually remove the two lines) and rebuild before doing anything else.