Holographic Context Engine (HCE)

February 20, 2026 · View on GitHub

A smart memory system for AI assistants. Instead of dumping entire conversation history into the context window, HCE retrieves only the most relevant memories — like how your brain recalls related experiences, not your entire life story.

User Query
    |
    v
+---------------------------+
|     HCE Middleware         |
|                           |
|  +---------+  +--------+  |
|  | Entity  |  |Semantic|  |
|  | Graph   |  | Tree   |  |
|  +---------+  +--------+  |
|        +--------+         |
|        | Focus  |         |
|        | Buffer |         |
|        +--------+         |
|           |               |
|    Context Budgeting      |
|    (pick best memories)   |
+---------------------------+
    |
    v
[Context Block + Query] --> LLM --> Response
                                      |
                              Store back into HCE

How It Works

HCE uses three parallel memory structures, inspired by how human memory works:

StructureHuman AnalogyWhat It StoresHow It Retrieves
Entity GraphAssociative memory ("reminds me of...")Concepts, files, people, and their relationshipsSpreading Activation — energy propagates through connections
Semantic TreeEpisodic memory (past experiences)Every conversation turn, organized hierarchicallyHierarchical Relevance Search — drill into relevant branches
Focus BufferShort-term memory (last few minutes)Last N conversation turnsRecency — most recent gets priority

A Context Budgeting algorithm (greedy knapsack) then picks the best memories that fit within the LLM's token budget, scored by Utility / Token_Cost.

Project Structure

hce-project/
├── hce_core.py            # EntityGraph (networkx) + Spreading Activation
├── semantic_tree.py        # SemanticTree + Hierarchical Relevance Search
├── entity_extractor.py     # Regex/heuristic NER for text -> entities
├── project_crawler.py      # Multi-language codebase indexer (Python/Java/JS/TS/Go/Rust/C/C++/Ruby)
├── hce_pipeline.py         # Pipeline orchestrator + Focus Buffer + Context Budgeting
├── hce_mcp_server.py       # MCP server for Claude Code integration
├── test_hce_core.py        # Tests for EntityGraph + Spreading Activation
├── test_semantic_tree.py   # Tests for SemanticTree + HRS
├── test_entity_extractor.py# Tests for entity extraction
├── test_project_crawler.py # Tests for project crawler
├── test_hce_pipeline.py    # Tests for pipeline + buffer + budgeting
├── architecture_plan.md    # Original design document
├── pyproject.toml          # Dependencies and project metadata
├── CLAUDE.md               # Instructions for Claude Code
└── .mcp.json               # MCP server registration

Quick Start

# Clone and set up
git clone <repo-url>
cd hce-project
python -m venv .venv
source .venv/bin/activate
pip install -e ".[dev]"

# Run tests
pytest

# Use with Claude Code (MCP integration)
# Just open the project in Claude Code — the MCP server starts automatically

Usage

As a Python library

from hce_pipeline import HCEPipeline

# Create a pipeline
pipeline = HCEPipeline(context_budget=4000)

# Store a conversation turn
pipeline.update(
    user_query="What is spreading activation?",
    ai_response="Spreading activation is an algorithm that propagates energy through a graph..."
)

# Later, retrieve relevant context for a new query
context = pipeline.retrieve_context("How does the entity graph find related concepts?")
print(context)
# >> ## Related Knowledge
# >> - [concept] spreading_activation (score: 0.85)
# >> - [concept] entity_graph (score: 0.72)
# >> ...

# Or wrap an LLM chat function
def my_chat(prompt: str) -> str:
    # call your LLM here
    return llm.generate(prompt)

smart_chat = pipeline.wrap_chat(my_chat)
response = smart_chat("How does the entity graph find related concepts?")
# HCE automatically enriches the prompt with context and stores the result

Index a codebase

from project_crawler import crawl_project

# Supports Python, Java, JS/TS, Go, Rust, C/C++, Ruby
graph = crawl_project("/path/to/your/project")
print(f"Found {graph.node_count} entities and {graph.edge_count} relationships")

Persistence

# Save state
pipeline.save("~/.hce_state")

# Load later
pipeline = HCEPipeline.load("~/.hce_state")

With Claude Code & GitHub Copilot CLI (MCP)

HCE integrates with any tool that supports the Model Context Protocol, including Claude Code and GitHub Copilot CLI. It provides persistent memory across sessions — automatically storing important exchanges and retrieving relevant context.

Claude Code Setup

Add this to your project's .mcp.json (adjust paths to your environment):

{
  "mcpServers": {
    "hce": {
      "command": "/path/to/your/.venv/bin/python",
      "args": ["/path/to/hce_mcp_server.py"]
    }
  }
}

Then add the auto-behavior rules from CLAUDE.md to your project so Claude Code calls HCE tools automatically.

GitHub Copilot CLI Setup

Add HCE to your Copilot CLI MCP config at ~/.copilot/mcp-config.json:

{
  "mcpServers": {
    "hce": {
      "type": "local",
      "command": "/path/to/your/.venv/bin/python",
      "args": ["/path/to/hce_mcp_server.py"]
    }
  }
}

Note: Claude Code reads CLAUDE.md for auto-behavior rules (when to store/retrieve automatically). Copilot CLI does not — you'll need to explicitly ask it to use HCE tools, or configure similar rules in Copilot's system prompt.

Other MCP-Compatible Tools

HCE works with any MCP client, including VS Code (Copilot Chat), Cursor, Windsurf, Zed, and Claude Desktop. Check each tool's docs for how to register a custom MCP server.

MCP Tools

ToolPurposeWhen it's called
hce_statusShow memory statistics (nodes, edges, interactions, buffer)On session start
hce_retrieve_contextSearch all 3 structures and return curated context within token budgetBefore answering codebase/architecture/history questions
hce_store_interactionSave a conversation turn into graph, tree, and bufferAfter important exchanges (design decisions, bug fixes, features)
hce_crawl_projectIndex a codebase (Python, Java, JS/TS, Go, Rust, C/C++, Ruby) into the entity graphWhen graph is empty or user requests re-indexing
hce_search_graphSearch the entity graph via spreading activationWhen looking for related code entities or concepts
hce_clear_memoryReset all HCE state (graph, tree, buffer)Only when explicitly requested

Example: What happens in a session

Session Start:
  Claude calls hce_status → sees 313 nodes, 7 stored interactions
  Graph already populated → no need to crawl

User: "How does the authentication system work?"
  Claude calls hce_retrieve_context("authentication system")
  → HCE returns: 2 graph entities (login.py, validate_token),
    1 past conversation about auth design, last 2 recent turns
  → All packed within 4,000 token budget
  Claude answers using that context

User: "Let's switch from JWT to session cookies"
  Claude implements the change, then calls hce_store_interaction(...)
  → Decision stored in all 3 structures for future sessions

Next Session (days later):
  User: "Why did we switch away from JWT?"
  Claude calls hce_retrieve_context → finds the stored decision
  Claude: "We switched to session cookies because..."

All data is local

HCE stores everything at ~/.hce_state/ on your machine. No cloud, no external API calls. See the FAQ for more details.

FAQ

"I installed HCE but my context keeps growing — is it broken?" No! HCE doesn't shrink your current conversation. It provides cross-session memory and smart retrieval for LLM apps. See the full FAQ for this and other common questions.

Architecture Deep Dive

Entity Graph (hce_core.py)

A typed property graph backed by networkx.MultiDiGraph.

  • Node types: File, Function, Concept, Person, Event
  • Edge types: Imports, Calls, Relates_To, Part_Of
  • Retrieval: Spreading Activation — seed nodes get energy, which propagates to neighbors with a decay factor
[login.py] --Imports--> [user_model.py] --Part_Of--> [auth/]
     |                        |
  Calls                   Calls
     v                        v
[validate()]           [get_user()]

Semantic Tree (semantic_tree.py)

A Merkle/Aggregation tree where leaves are raw conversation turns and internal nodes are summaries.

        [Root: summary of everything]
       /                            \
  [Summary: turns 1-4]        [Summary: turns 5-8]
   /    |    |    \             /    |    |    \
 T1    T2   T3   T4          T5   T6   T7   T8   <-- leaves (raw turns)

Hierarchical Relevance Search (HRS): Start at the root, compute similarity, recurse into promising branches, prune low-scoring ones.

Context Budgeting (hce_pipeline.py)

A greedy knapsack algorithm that selects the best memories within a token budget:

  1. Collect candidates from all three structures
  2. Score each by Utility / Token_Cost (efficiency ratio)
  3. Greedily pack the highest-efficiency candidates until budget is full

Tech Stack

  • Python 3.10+
  • networkx — Graph data structure
  • mcp — Model Context Protocol for Claude Code integration
  • pytest — Testing

Current Status

All 4 implementation phases are complete:

  • Phase 1: EntityGraph + Spreading Activation
  • Phase 2: SemanticTree + Hierarchical Relevance Search
  • Phase 3: Project Crawler + Entity Extractor
  • Phase 4: Pipeline Middleware + MCP Server

194 tests passing. See the architecture plan for the full design rationale.

Scalability

HCE works well for single-developer local use (up to ~10K graph nodes, hundreds of interactions). For scaling beyond that, see the Scalability Guide — it covers current capacity, known bottlenecks, and the recommended upgrade path (SQLite backend, semantic embeddings, incremental tree insertion).

Known Limitations

  • Vectorizer: Uses feature-hashing (bag-of-words), not semantic embeddings. "car" and "automobile" won't match.
  • Summarizer: Extractive (first sentences), not abstractive. No LLM summarization yet.
  • NER: Regex/heuristic-based, not ML. Misses many entities in natural text.
  • Non-Python parsers: Java, JS/TS, Go, Rust, C/C++, and Ruby use regex-based parsing (no semantic understanding, may miss complex patterns). Python uses full AST parsing.
  • Platform: File locking uses POSIX fcntl.flock() — not available on Windows without adaptation.

For a full analysis of scaling limits and fixes, see SCALABILITY.md.

Competitive Landscape

HCE's three-structure parallel retrieval with knapsack budgeting is unique among LLM memory solutions. See COMPETITORS.md for a detailed comparison with Mem0, Letta (MemGPT), Zep, Cognee, and SimpleMem — including where HCE leads, where it needs improvement, and the roadmap to close the gaps.

License

MIT