v9.0.0 - Phase 0 Ontology Foundation

⚠️ MAJOR RELEASE - Contains breaking changes. Please read the Migration Guide before upgrading.

Breaking Changes

1. Memory Type Ontology

What Changed:

Legacy memory types (task, note, standard) are deprecated
New formal taxonomy: 5 base types with 21 subtypes
- observation, decision, learning, error, pattern
Type validation now defaults to 'observation' for invalid types

Migration:

# Run migration script to update existing memories
python scripts/migrate_ontology.py

2. Asymmetric Relationships

What Changed:

Asymmetric relationships (causes, fixes, supports, follows) now store only directed edges
Symmetric relationships (related, contradicts) continue storing bidirectional edges
Database migration (010) automatically removes incorrect reverse edges

Code Changes Required:

# OLD (will no longer work):
result = storage.find_connected(memory_id, relationship_type="causes")

# NEW (correct approach):
result = storage.find_connected(
    memory_id,
    relationship_type="causes",
    direction="both"  # Explicit direction required
)

New Features

Phase 0 Ontology Foundation (PR #347)

Memory Type Ontology: Formal classification system with hierarchical taxonomy
Tag Taxonomy: Structured namespace system (sys:, q:, proj:, topic:, t:, user:)
Typed Relationships: 6 relationship types for knowledge graphs
Lightweight Reasoning Engine: Foundation for causal inference (SemanticReasoner class)
97.5x Performance: Caching improvements in ontology validation

Response Size Limiter (PR #344)

Added max_response_chars parameter to 5 memory retrieval tools
Prevents context window overflow
Truncates at memory boundaries (never mid-content)
Environment variable: MCP_MAX_RESPONSE_CHARS

Bug Fixes

Fixed 33 API/HTTP test failures (Issue #351, PR #352) - Import errors resolved
Fixed validation tests (PR #350) - 38 legacy types migrated to new ontology
Fixed bidirectional storage (Issue #348, PR #349) - Asymmetric relationships corrected

Performance Improvements

get_all_types(): 97.5x speedup via module-level caching
get_parent_type(): 35.9x speedup via cached reverse lookup map
Tag validation: 47.3% speedup (eliminated double parsing)

Test Results

829/914 tests passing (90.7%)
80 new ontology tests with 100% backward compatibility
All API/HTTP integration tests passing

Installation

pip install --upgrade mcp-memory-service

Support

Full Changelog: v8.76.0...v9.0.0

doobidoo/mcp-memory-service v9.0.0 v9.0.0 - Phase 0 Ontology Foundation (Major Release) on GitHub