#1262 split `get_or_create_collection` into `get_collection` + fallback
`create_collection` inside `ChromaBackend.get_collection`, fixing the
chromadb 1.5.x Rust-binding SIGSEGV that fires when stored collection
metadata differs from the call-site's `_HNSW_BLOAT_GUARD` payload.
The MCP server's `_get_collection(create=True)` carries the same metadata
payload at `mcp_server.py:287` and routes through chromadb's Python
client directly, bypassing the backend layer. Both `tool_add_drawer`
and `tool_diary_write` reach this site on every invocation, and the
Stop hook fires `mempalace_diary_write` at session end — which was
exactly the crash path #1089 named.
Apply the same try/except split here so legacy palaces whose stored
metadata predates the bloat-guard expansion no longer crash on the
MCP-server reopen path. Regression test patches
`get_or_create_collection` at the chromadb client class level (not the
instance — chromadb's mtime-change detection rebuilds the client between
calls, so an instance-level spy doesn't survive) and asserts the second
`_get_collection(create=True)` call never reaches it.
Igor Lins e Silva
9dd56ecb0a