SINT-UA v2.1 — Agent Memory System for OpenCode

A structured memory system with hash-chain provenance, temporal decay, drift detection, provenance archaeology, vector embeddings, and git integration for OpenCode agents.

What This Is

This is not another prompt template. This is infrastructure for AI agent memory:

• Structured JSON blocks with semantic registers (SENSE/FACT/LOGIC/OPINION/ACTION)
• Hash-chain provenance — tamper-evident chain of all memory blocks
• Temporal decay — memory blocks "cool down" over time like human memory
• Drift detection — monitors when agent starts hallucinating or losing register discipline
• Provenance archaeology — trace any decision back to its root facts
• Vector embeddings — semantic search with sentence-transformers
• Git integration — link memory blocks to git commits for audit trail

Architecture

┌─────────────────────────────────────────────────────────────┐
│                    sint-main (primary agent)                 │
│  Auto-reads memory → Classifies task → Delegates            │
└─────────┬──────────────────────┬────────────────────────────┘
          │                      │
          ▼                      ▼
┌─────────────────┐    ┌─────────────────┐
│ sint-critic     │    │ sint-scribe     │
│ • Verification  │    │ • Memory ops    │
│ • Fact-check    │    │ • Block I/O     │
│ • Code review   │    │ • Chain verify  │
└─────────────────┘    └─────────────────┘
          │                      │
          └──────────┬───────────┘
                     ▼
┌─────────────────────────────────────────────────────────────┐
│                  sint-memory MCP Server                     │
│  16 tools: read/write/search/verify/decay/drift/trace       │
└─────────────────────────────────────────────────────────────┘
                     │
                     ▼
┌─────────────────────────────────────────────────────────────┐
│               Hash-Chain Memory (.opencode/memory/)         │
│  blocks/*.json — chain.jsonl — state.json — sessions/       │
└─────────────────────────────────────────────────────────────┘

Components

Agents (.opencode/agents/)

Agent	Role	Mode
sint-main	Primary orchestrator, auto-reads memory, classifies, delegates	primary
sint-critic	Independent verification — register compliance, logic, sources	subagent
sint-scribe	Memory management — block I/O, chain operations	subagent
sint-router	Task classification by semantic register and domain	subagent

MCP Server

Python MCP server providing 20 tools for memory operations:

memory_read_state          memory_write_block
memory_read_block          memory_write_session
memory_read_blocks         memory_update_state
memory_search              memory_verify_chain
memory_get_chain_tail      memory_stats
memory_apply_decay         memory_heat_block
memory_relevance_tiers     memory_drift_check
memory_trace_provenance    git_link_blocks
git_trace_block            git_timeline
embeddings_index           embeddings_search

CLI Tool (sint)

sint status          # Memory stats and current focus
sint recent [n]      # Last N chain entries
sint search <query>  # Search blocks
sint block <id>      # Block details
sint verify          # Verify hash chain
sint add <reg> <text> # Add new block
sint decay           # Apply temporal decay
sint drift           # Drift detection
sint trace <id>      # Provenance archaeology
sint git link        # Link blocks to git commits
sint git timeline    # Combined block + commit timeline
sint dashboard       # Full dashboard

Vector Embeddings (sint-embeddings)

sint-embeddings index       # Build/update embedding index
sint-embeddings search <q>  # Semantic search
sint-embeddings similar <id> # Find similar blocks

Git Integration (sint-git)

sint-git link         # Link blocks to git commits
sint-git trace <id>   # Trace block through git history
sint-git timeline     # Combined timeline
sint-git info         # Current commit details

Plugin (sint-hooks)

TypeScript plugin with hooks:

• tool.execute.after — auto-log significant findings
• chat.system.transform — inject memory context
• session.compacting — preserve across compaction

Commands

Command	What it does
/session-start	Read memory, present context
/session-end	Write summary, update state
/verify [content]	Run sint-critic
/memory [query]	Query memory system
/dashboard	Full dashboard view

Memory Blocks

Each block is a JSON file with semantic register:

{
  "id": "0042",
  "register": "FACT",
  "prev_hash": "a3f2c...",
  "hash": "7b1d9...",
  "timestamp": "2026-07-14T12:00:00Z",
  "project": "DSA",
  "content": "3D attenuation verified: near=0.25 far=0.0025",
  "source": "bench run 2026-07-13",
  "confidence": 0.95,
  "tags": ["3d", "attenuation", "verified"],
  "links": ["0038"]
}

Registers

Register	Use for
SENSE	Raw observations, tool output, logs
FACT	Verified claims with sources
LOGIC	Inferences from FACT/SENSE
OPINION	Subjective assessments (must be labeled)
ACTION	Execution plans, next steps

Hash-Chain

Every block references the previous block's hash:

block_N.prev_hash = block_{N-1}.hash
block_N.hash = sha256(id + register + content + prev_hash)[:16]

Tamper-evident: modifying any block breaks all subsequent hashes.

Novel Features

Temporal Decay

Memory blocks have relevance scores that decay over time:

• Hot (relevance > 0.7): Recently accessed or highly linked
• Warm (0.4-0.7): Still relevant
• Cool (0.15-0.4): Aging
• Cold (< 0.15): Nearly forgotten

sint decay    # Apply decay to all blocks
sint heat 0042 # Heat up block for 7 days

Drift Detection

Monitors agent behavior across sessions:

• Register distribution (are opinions labeled as facts?)
• Source coverage (are claims traceable?)
• Confidence trends
• Topic consistency

sint drift    # Check for anomalies

Provenance Archaeology

Trace any decision back to its root facts:

sint trace 0042  # Full reasoning chain
sint trace 0042 --tree  # Dependency tree

Vector Embeddings

Semantic search using sentence-transformers with all-MiniLM-L6-v2 (384-dim):

sint-embeddings search "3D audio attenuation"  # Returns top 10 similar blocks
sint-embeddings similar 0005  # Find blocks similar to block 0005

Embedding index stored at .opencode/memory/embeddings/.

Git Integration

Link memory blocks to git commits for complete audit trail:

sint git link         # Link blocks to recent commits by timestamp
sint git trace 0042   # Show git commits linked to block
sint git timeline     # Combined memory + git timeline
sint git info         # Current commit details

Setup

1. Copy to your project

cp -r .opencode/agents/ /path/to/your/project/.opencode/agents/
cp -r .opencode/mcp/ /path/to/your/project/.opencode/mcp/
cp -r .opencode/plugin/ /path/to/your/project/.opencode/plugin/
cp -r .opencode/commands/ /path/to/your/project/.opencode/commands/
cp .opencode/bin/sint /usr/local/bin/

2. Install dependencies

pip install mcp sentence-transformers faiss-cpu

3. Update opencode.json

Add to your opencode.json:

{
  "default_agent": "sint-main",
  "agent": {
    "sint-main": { "mode": "primary" },
    "sint-critic": { "mode": "subagent" },
    "sint-scribe": { "mode": "subagent" }
  },
  "mcp": {
    "sint-memory": {
      "type": "local",
      "command": ["python3", "/path/to/.opencode/mcp/sint-memory/server.py"]
    }
  },
  "plugin": ["/path/to/.opencode/plugin/sint-hooks.ts"]
}

4. Restart OpenCode

# Changes require restart
opencode

Usage

Automatic (default)

After setup, sint-main runs automatically:

1. Reads memory state
2. Greets with context
3. Classifies tasks
4. Delegates to specialists
5. Plugin auto-logs findings

Manual

# Terminal
sint status
sint drift
sint trace 0042

# In OpenCode
/session-start
/verify this claim
/memory "3D attenuation"
/dashboard

How It's Different

Typical Agent Systems	SINT-UA v2.1
Flat context window	Structured JSON blocks
No provenance	Hash-chain audit trail
Memory = full context	Temporal decay, relevance scoring
No drift detection	Cross-session anomaly monitoring
Manual memory updates	Auto-logging via plugin hooks
"Trust me"	Cryptographic verification

File Structure

.opencode/
├── agents/
│   ├── sint-main.md
│   ├── sint-critic.md
│   ├── sint-scribe.md
│   └── sint-router.md
├── commands/
│   ├── session-start.md
│   ├── session-end.md
│   ├── verify.md
│   ├── memory.md
│   └── dashboard.md
├── mcp/sint-memory/
│   └── server.py
├── plugin/
│   └── sint-hooks.ts
├── memory/
│   ├── state.json
│   ├── chain.jsonl
│   ├── blocks/
│   └── sessions/
├── bin/
│   ├── sint
│   ├── sint-decay
│   ├── sint-drift
│   └── sint-archaeology
└── skills/
    └── memory-system/SKILL.md

License

MIT