ChromaDB can return None for drawers without metadata (legacy data,
partial writes — same root cause as upstream #1020 / our PR #1094).
build_graph at line 95 called meta.get("room", "") unconditionally,
which AttributeErrors on None and takes out every consumer of
build_graph for the whole call path: graph_stats, find_tunnels,
traverse, and (most visibly) the daemon's /stats endpoint.
Caught 2026-04-25 by palace-daemon's verify-routes.sh smoke test
against the canonical 151K-drawer palace — /stats was 500-ing on a
single None drawer.
Adds `if meta is None: continue` guard. Closes the same gap upstream's
#999 None-metadata audit closed in searcher.py / mcp_server.py /
miner.status, just in a different file the audit didn't reach. The
graph-build is recoverable: skipping a single None drawer doesn't
distort the graph since build_graph already filters
`room and room != "general" and wing` — a missing-metadata drawer was
never going to participate anyway.
Test: TestBuildGraph::test_none_metadata_does_not_crash mixes a None
entry into a 3-drawer fixture and asserts the two real drawers are
processed normally.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
build_graph() scans every drawer's metadata in 1000-item batches on
every call — O(n) per graph build with no caching. At 50K+ drawers
this costs several seconds per MCP tool call (traverse, find_tunnels,
graph_stats all call build_graph on every invocation).
Add a module-level cache (nodes + edges + timestamp) with a 60-second
TTL. Cache is invalidated via invalidate_graph_cache(), exported for
write operations to call. Tests updated with setup_method cache resets
and two new tests verifying cache hit and invalidation behaviour.
jp