store: Auto-edge creation on memory_store in MCP server

graph/decisions/auto-edge-creation-on-memory-store-in-mcp-server-ee85bf.md

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+---
+id: ee85bf89-93f0-48e4-b911-7ddc18a735b5
+type: decision
+title: "Auto-edge creation on memory_store in MCP server"
+tags: [cognitive-memory, edges, mcp, automation, architecture, mcp-server]
+importance: 0.8
+confidence: 0.8
+created: "2026-03-01T04:12:39.570452+00:00"
+updated: "2026-03-01T04:12:39.570452+00:00"
+---
+
+# Auto-edge Creation on memory_store in MCP Server
+
+## Decision
+
+Implemented auto-edge creation in `mcp_server.py` that runs after every `memory_store` call.
+
+## Implementation
+
+The `_auto_create_edges()` helper:
+- Uses `client.recall(title + tags, limit=5, semantic=True)` to find related memories
+- Applies type-pair heuristics from `AUTO_EDGE_HEURISTICS` table (subset of edge-proposer.py) to choose edge types: SOLVES, BUILDS_ON, RELATED_TO
+- Calls `client.relate()` for up to 3 edges
+- Returns `(edges_list, error_string_or_None)` tuple — never raises so store always succeeds
+
+## Response Shape
+
+Response includes `auto_edges` array and optional `auto_edge_error` key.
+
+## Key Design Decisions
+
+1. Same-type pairs excluded as too noisy
+2. REQUIRES/FOLLOWS excluded as needing stronger signal
+3. Keyword-only fallback requires tag overlap to prevent spurious edges
+4. Similarity score passed as edge strength
+5. Description arrow matches actual from/to direction (after direction resolution)