Windows Codex app /compact fails with remote compaction v2 expected exactly one output item

Summary

The Windows Codex app fails when running /compact with a remote compaction v2 output parsing error.

Error

Error running remote compact task: Fatal error: remote compaction v2 expected exactly one compaction output item, got 0 from 2 output items

I have also seen a similar failure in another thread:

Error running remote compact task: Fatal error: remote compaction v2 expected exactly one compaction output item, got 0 from 4 output items

Environment

• Platform: Windows
• Codex app package: OpenAI.Codex_26.616.10790.0_x64__2p2nqsd0c76g0
• App version shown by winget/Microsoft Store listing: 26.616.10790.0
• Global Codex CLI is working normally and should not be changed.

Log evidence

Codex app logs show remote_compaction_v2 enabled:

Features enabled enabledFeatures="enable_request_compression, remote_compaction_v2, collaboration_modes, personality, request_rule, image_generation, resize_all_images, image_detail_original, workspace_dependencies, guardian_approval, apps_mcp_path_override, apply_patch_streaming_events, workspace_owner_usage_nudge, thread_tools, unified_exec, enable_mcp_apps, apps, plugins, tool_call_mcp_elicitation"

There was also a related app-side compact failure in the logs:

Failed to run pre-sampling compact

Relevant local log directory:

C:\Users\Administrator\AppData\Local\Codex\Logs\2026\06\25

Troubleshooting already tried

• Closed and reopened the Codex app.
• Repaired the Codex app from Windows app settings.
• Reinstalled the Codex app.
• The problem still occurs after reinstalling.
• The global Codex CLI works normally, so this appears specific to the Windows Codex app or the remote remote_compaction_v2 path.

Expected behavior

/compact should summarize the current visible conversation and continue the thread normally.

Actual behavior

/compact fails with the remote compaction v2 error above and does not produce a compacted thread state.