materialize() removed the temp hard link in a finally that ran BEFORE
syncDir() and before state.materialized/cursor advanced. If link()
succeeded (log published) but the temp rm then threw, materialize()
rejected after publishing — leaving state.materialized false, so the
buffered events stayed unpersisted and every retry wedged on the
"already exists" exists() backstop.
Restructured to the robust shape: track link() success; on link failure
remove the temp (the only reference) before propagating; on success
fsync the directory, mark materialized, THEN best-effort remove the
now-redundant temp link (a leftover *.tmp is harmless and never read).
A temp-rm failure can no longer reject a session whose log published.
1b1385e4f7