feat(core): port server/tools_query.py to backend-neutral queries#20
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Fourth step of the Kuzu -> DuckDB migration. The most-used MCP tool
file (symbol_lookup, find_callers, find_callees, imports_of,
search_symbols, subgraph) now uses backend-neutral helpers. Both
backends answer these MCP tools identically.
What lands:
- codegraph/core/protocol.py: three new GraphDB methods covering the
query patterns in tools_query.py.
- find_nodes(label, where=..., contains=..., return_fields=...,
limit=...) -> list[dict]
Used by symbol_lookup + search_symbols. Both exact match (=) and
substring (CONTAINS / LIKE) supported; multi-field substrings get
OR'd, so search_symbols on TFResource matches when either name or
type contains the query.
- find_neighbors(edge_type, src_key=..., dst_key=..., src_where=...,
dst_where=..., return_src=..., return_dst=..., return_edge=...)
-> list[dict]
Used by find_callers, find_callees, imports_of, who_imports. Result
rows are flattened to {src_<field>: ..., dst_<field>: ...,
edge_<field>: ...} so the caller can pick what they need without
every tool reaching into Kuzu's "table.field" shape.
- reach_via_edge(edge_type, start_key, max_depth=..., return_fields=...)
-> list[dict]
Used by subgraph at depth > 1. Backed by Cypher's `*1..n` path
syntax on Kuzu and a recursive CTE on DuckDB.
- codegraph/core/db_kuzu.py + db_duckdb.py: all three helpers
implemented on both backends. Edge tables in DuckDB use composite
JOINs (e.g. `FROM edge_calls e, function a, function b WHERE
e.from_id = a.id AND e.to_id = b.id`) so anchoring on either side
and filtering by neighbor fields uses the same SQL shape.
- codegraph/server/tools_query.py: every conn.execute() call gone,
the _rows import gone. Each of the six MCP tools (symbol_lookup,
find_callers, find_callees, imports_of, search_symbols, subgraph)
goes through one or two GraphDB helper calls and translates the
result dicts into the tool's JSON payload.
- tests/test_core/test_graph_helpers.py: 18 new parametrized tests
covering find_nodes (where + contains + multi-field OR + limit),
find_neighbors (anchor on src, anchor on dst via where, edge props),
and reach_via_edge (single hop + two-hop).
End-to-end verification on a 3-function 2-file repo:
Kuzu:
symbol_lookup helper -> /tmp/.../a.py
find_callers helper -> [caller, wrapper]
imports_of /b.py -> [{ /a.py, 'helper' }]
DuckDB (CGH_DB=duckdb):
symbol_lookup helper -> /tmp/.../a.py
find_callers helper -> [caller, wrapper]
imports_of /b.py -> [{ /a.py, 'helper' }]
Identical results. 292 tests pass (was 274 + 18 new = 292).
What's NOT in this PR (next migration PRs):
- tools_viz.py (19 Cypher queries — bigger file, dedicated PR)
- tools_arch.py (3 queries)
- tools_docs.py (6 queries)
- analysis/{context_builder,dead_code}.py (5 queries)
- cli/commands_monitor.py (12 stats queries — separate task #10)
- federation.py (kuzu-direct opens — task #11)
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Summary
Fourth PR in the Kuzu → DuckDB migration. The most-used MCP tool file (`symbol_lookup`, `find_callers`, `find_callees`, `imports_of`, `search_symbols`, `subgraph`) now uses backend-neutral helpers. Both backends return identical results for these tools.
What lands
End-to-end verification
3-function 2-file repo with `a.py` defining `helper` + `caller`, `b.py` importing helper:
Test count
274 → 292 (+18 new parity tests).
Not in this PR (follow-ups)