fix(falkordb): route single-group reads onto the group's graph

[yimtheppariyapol]

Summary

Single-group reads against FalkorDB return nothing even when the data is physically present in the group's graph. handle_multiple_group_ids only re-routed the driver onto the group graph when len(group_ids) > 1, so a single-group read fell through to the base driver (pinned at default_db) and queried the wrong graph.

Root cause

FalkorDB stores each group_id in its own graph, so a read must clone the driver onto that graph. The decorator gated that routing on len(group_ids) > 1. The write path mutates self.driver onto the group graph, which is why same-process write-then-read tests masked the bug — the reader inherited the mutated driver. A fresh reader process with a single group_id queried default_db and got 0 results.

Reproduced: GRAPH.QUERY <group> showed episodes + facts present; a single-group get_episodes([group]) returned 0; a two-group [group, other] search returned everything (because len > 1 routed).

What changed

• decorators.py — replace the len > 1 gate with a blank-filtered routable_group_ids (mirrors search()'s != [''] convention). A single real group now routes; a ['']/[None] group no longer routes onto an empty graph name.
• falkordb_driver.py — memoize clone() per database. __init__ schedules build_indices_and_constraints() on every construction — load-bearing exactly once per group, but pure churn on every subsequent read now that single-group reads clone. Caching keeps the once-per-group index build while removing the per-call constructor cost.

Verification

• Single-group get_episodes([group]) now returns the group's facts against a live FalkorDB (previously 0).
• Memoized clone(): repeated clone of the same db returns the same object (no churn); default_group_id maps to default_db; self-clone returns self; a new group is constructed once then cached, and the new group's graph still gets its indices built.

Follow-up (not in this PR)

The write-path self.driver mutation in graphiti.py could be made non-mutating so reads and writes share one routing mechanism, removing the asymmetry that masked this bug.

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[yimtheppariyapol]

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[yimtheppariyapol]

I have read the CLA Document and I hereby sign the CLA behalf on myself, e-mail: [email protected]