MCP server: mempalace_list_wings and mempalace_get_taxonomy return empty despite data in palace

[fubak]

Bug

mempalace_list_wings and mempalace_get_taxonomy return empty objects via the MCP server, even when the palace has data. mempalace_status correctly reports the total drawer count but returns wings: {} and rooms: {}.

Steps to Reproduce

# Mine a project
mempalace mine /path/to/project --wing myproject

# Verify data exists via CLI
mempalace status
# → correctly shows wings, rooms, and drawer counts

# Start MCP server and call tools
mempalace_status       # → total_drawers: 95964, wings: {}, rooms: {}
mempalace_list_wings   # → { "wings": {} }
mempalace_get_taxonomy # → { "taxonomy": {} }

Expected

All three tools should return the same wing/room structure that the CLI mempalace status command shows.

Actual

{ "wings": {} }
{ "taxonomy": {} }

Environment

• mempalace 3.0.0
• Python 3.12.3
• ChromaDB 1.5.6
• Claude Code MCP integration
• Palace: single collection mempalace_drawers, 95,964 documents, all with wing and room metadata fields confirmed via direct ChromaDB query

Additional Context

Direct ChromaDB inspection confirms the metadata is present and correctly structured:

import chromadb
client = chromadb.PersistentClient(path='~/.mempalace/palace')
coll = client.get_collection('mempalace_drawers')
results = coll.get(limit=3, include=['metadatas'])
# → {'wing': 'agent-action-firewall', 'room': 'testing', ...}

mempalace_search with wing filter works correctly and returns the right results — so the data and metadata are intact. Only the taxonomy-building tools are affected.

The CLI mempalace status works correctly, suggesting the MCP server uses a different code path to build the wing/room taxonomy that isn't querying ChromaDB metadata properly.