Bound session-memory graph neighborhood reads

[8Dionysus]

Summary

• resolve graph aliases through bounded shard route_terms index probes
• traverse the graph store with an indexed, bounded BFS and compact the MCP response
• defer unresolved deep archive expansion instead of running a hidden bulk fallback inside MCP
• expose the deferred state through entity dossier packets

Verification

• 121 passed for mcp/services/aoa-session-memory-mcp/tests
• ruff check on the changed source and tests
• live owner-admitted probe against the 34 GB graph store: 313 ms runtime, 51 MB peak memory, 0 swap, no archive command

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Surface route-term resolution failures

When the synthetic graph-node candidates miss and alias resolution depends on search/shards/*/route_terms, a malformed/unreadable shard or stale route-term match reaches this return after _graph_route_term_node_candidates has collected diagnostics or matched IDs. Returning None discards that evidence, so graph_neighborhood() emits the generic mcp_bounded_graph_deferred "no indexed graph node" response even though the alias read model is broken or inconsistent; carry the route-term resolution diagnostics/matches into the deferred/error payload instead.

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