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fix(palace): postgres backend is a multi-process-writer backend #398

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Merged
jphein merged 1 commit into from
Aug 10, 2026
Merged

fix(palace): postgres backend is a multi-process-writer backend #398

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8 changes: 7 additions & 1 deletion mempalace/palace.py
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Original file line number Diff line number Diff line change
Expand Up @@ -507,7 +507,13 @@ def resolve_backend_name(palace_path: str, explicit: Optional[str] = None) -> st
return selected


_MULTI_PROCESS_WRITER_BACKENDS = frozenset({"pgvector", "qdrant"})
# Fork: "postgres" (the #665-lineage backend behind palace-daemon) delegates
# all cross-process concurrency to the postgres server, exactly like
# "pgvector" — without it here, the daemon's embedded MCP server takes the
# process-lifetime writer lease and every `mempalace mine` subprocess the
# daemon spawns for /mine refuses with "palace is held by PID <daemon>"
# (production incident 2026-08-09, first post-v3.7.0 deploy).
_MULTI_PROCESS_WRITER_BACKENDS = frozenset({"pgvector", "qdrant", "postgres"})


def backend_requires_single_writer(backend_name: str) -> bool:
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4 changes: 4 additions & 0 deletions tests/test_palace.py
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Expand Up @@ -37,6 +37,10 @@ def test_backend_writer_ownership_remains_conservative_for_unknown_backend():
assert backend_requires_single_writer("plugin_backend") is True
assert backend_requires_single_writer("qdrant") is False
assert backend_requires_single_writer("pgvector") is False
# Fork: postgres coordinates concurrent clients server-side; the daemon
# must NOT take the writer lease or its spawned /mine CLI subprocesses
# self-refuse ("palace is held by PID <daemon>", 2026-08-09 incident).
assert backend_requires_single_writer("postgres") is False


def _capture():
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