EPIC: graphrag_consistency rule pack — deterministic denoise -> detect -> resolve governance stage

[se-jo-ma]

EPIC. MemGraphRAG is demonstrated as a transferable graph constructor that improves four downstream GraphRAG frameworks. Fathom's analog is a curated, versioned rule pack that acts as the deterministic governance stage in a GraphRAG construction pipeline: an external extractor emits candidate triples; fathom denoises (schema-frequency), detects conflicts, and emits allow/deny/escalate per triple before it enters the graph — replacing non-deterministic LLM filtering with auditable rules. Zero core changes.

Composition (sub-work).

• Schema-frequency operator + candidate/stable contract — (linked issue)
• Conflict-detection rule pack (mutual_exclusion / temporal / granularity) — (linked issue)
• This epic: assemble both into a shipped graphrag_consistency pack with ordered denoise→detect→(escalate) modules + external-extractor wiring over MCP.

Where.

• New src/fathom/rule_packs/graphrag_consistency/{templates,modules,rules} (follow hipaa/ pack layout).
• Register in pyproject.toml [project.entry-points."fathom.packs"] :144-149; discovered via packs.py RulePackLoader.discover :18 / load :44; mounted via Engine.load_pack (engine.py:856).
• Module ordering via the focus stack (evaluator.py _setup_focus_stack :79).

Templates. candidate_triple(head, relation, tail, source_passage, support_count), stable_schema(relation_type), mutual_exclusion(relation, tail_a, tail_b), conflict(...).

Acceptance criteria.

• Pack promotes schemas past τ, denies triples whose relation never stabilizes, escalates detected conflicts — end-to-end on a sample corpus.
• External extractor drives it over MCP; decisions auditable.

Notes. Depends on the two linked features landing first. τ and mutual-exclusion lists are domain-specific. Relates to #73.

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Source: arXiv:2606.00610v1 — "MemGraphRAG: Memory-based Multi-Agent System for Graph Retrieval-Augmented Generation". Distilled from arXiv-research/2606.00610v1/analysis.md; file refs verified against current main by the analysis pass.

[se-jo-ma]

Sub-work tracked in:

• Operator: schema_frequency_exceeds + candidate/stable schema rule-pack contract (frequency-tau denoising) #145 — schema_frequency_exceeds operator + candidate/stable contract
• Rule pack: conflict detection (mutual_exclusion / temporal / granularity) over the fact layer #146 — conflict-detection rule pack (mutual_exclusion / temporal / granularity)

Boundary constraint (no embeddings/PPR in the symbolic core): #148