Properly skip publishing if checkpoints are present, but publishing is disabled

[marta-lokhova]

The bug showed up in simulations, that kept running into nodes getting delayed by a few ledgers for no good reason.

Summary of the bug (AI-assisted):

• PutSnapshotFilesWork::doWork() busy-loops WORK_RUNNING forever when there are no writable history archives (Step 1 creates zero children, so it never reaches WORK_SUCCESS).
• The after-upgrade node hits this condition because it restored before-upgrade's DB, which contained a queued checkpoint publish for ledger 31. Its own config has localHistory = false. WorkScheduler::scheduleOne then hogs the main thread in CRANK_TIME_SLICE = 500 ms bursts, re-posting itself indefinitely.
• Every cross-thread post waits ~one slice, which is what causes post-on-main-thread.delay (mean 377 / max 530 ms). These delays causes the node to continue staying a few ledgers behind instead of properly catching up to the fast nodes

[Copilot]

Pull request overview

Prevents stale publish queues from busy-looping when no writable history archive exists.

Changes:

• Skip queued-history publication when publishing is unavailable.
• Fail defensively if snapshot work starts without writable archives.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/history/HistoryManagerImpl.cpp	Adds the publication guard.
src/historywork/PutSnapshotFilesWork.cpp	Prevents the empty-archive busy loop.

Comments suppressed due to low confidence (1)

src/history/HistoryManagerImpl.cpp:406

• Add a regression test for the reported restart/restore case: persist a queued checkpoint with publishing configured, reopen the same state without writable archives, call publishQueuedHistory(), and verify that it returns zero without scheduling work or stalling main-thread cranks. The existing history test suite covers persisted publish queues, but neither new no-archive path is exercised, so the busy-loop fix could regress unnoticed.

    if (!mApp.getHistoryArchiveManager().publishEnabled())