PR #13684 added workflow_id directly to ~9 dict literals across execution.py,
progress.py and main.py, along with executor.workflow_id and
server.last_workflow_id state. It was reverted because the execution layer
should not know about workflow concepts and because a finally-clear race
emitted workflow_id=None on the terminal "executing" frame.
Instead, register per-prompt metadata on PromptServer at submission time
and merge it onto outbound WebSocket payloads inside send_sync. The merge
keys off prompt_id (already present on every execution event), so
execution.py stays workflow-agnostic. Metadata is unregistered in main.py's
queue loop AFTER the terminal executing send, which structurally removes
the race.
- New comfy_execution/metadata.py: PromptMetadata TypedDict +
build_prompt_metadata + merge_prompt_metadata helpers.
- PromptServer: prompt_metadata registry (lock-protected), register on
post_prompt, merge in send_sync, expose get_prompt_metadata.
- jobs.py: extracted extract_workflow_id with strict isinstance guards;
_extract_job_metadata delegates.
- main.py: try/finally around the queue iteration; unregister after the
terminal "executing: {node: None}" send.
- execution.py PromptQueue: drop registry entries on wipe_queue /
delete_queue_item so cancellations don't leak.
- progress.py: look up workflow_id from the server registry for the
per-node nested copies and the binary preview metadata, matching #13684's
wire shape so the frontend needs no changes.
- Tests: tests-unit/server_test/test_prompt_metadata.py covers the merge,
the passthrough cases (no prompt_id, unknown prompt_id, binary payloads),
and the terminal-frame race regression.
