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MemTether — cross-client AI memory in action

MemTether — The AI Memory Court

Your agent remembers things. Who audits what it remembers?

MemTether is a local-first memory hub for multi-client AI agents. While most memory systems compete on retrieval accuracy, MemTether competes on governance: who wrote each fact, when it took effect, what it superseded, which conflicts a human adjudicated, and a tamper-evident hash chain anyone can verify — no code, no dependencies. Retrieval is provided (SGM deterministic SQL routing + hybrid embedding), but it is not the headline: agent memory that you can audit, correct, and trust is.

Coming from mem0, Zep, or Letta? examples/mem0_migration.py shows a complete round-trip migration from a mem0 JSON export — no mem0 SDK required.

$ memtether court fact-20261007-abc
+============================================================+
| MEMTETHER MEMORY COURT - CASE FILE                          |
| 1. CONTENT    Clash proxy port is 7897                      |
| 2. TEMPORAL   valid: 10-05 → present | known: 10-05 → now   |
| 3. PROVENANCE #1 remember by=codex → #2 correct by=user     |
| 4. CONFLICTS  case #3: vs fact-...old verdict=superseded    |
| 5. INTEGRITY  chain: PASS (3 anchors, 42 entries hashed)    |
+============================================================+

TL;DR

  • Your AI clients forget each other? Every agent keeps its own memory. MemTether gives them one shared, governed brain via file-level pointers — no cloud, no sync.
  • Your AI writes things it should not? Every memory carries a source identity and a hash-chained audit trail. Tamper with the database and the chain detects it — run python examples/audit_chain_demo.py to see it turn red.
  • Your AI changed its mind? Corrections never delete. Bi-temporal supersession keeps who-changed-what-when-why forever, queryable at any past point in time.

Run it yourself:

$ python examples/audit_chain_demo.py
写入 25 条记忆(自动生成 2 个审计锚点)...
篡改前 verify_chain: PASS {'anchors': 2, 'entries_covered': 20}
模拟攻击者直接改库...
篡改后 verify_chain: FAIL {'reason': 'chain hash mismatch'}
✅ 哈希链成功检测到篡改!

> Note: ntries_covered: 20 with 25 writes is expected — the hash chain anchors every 10 audit entries, so the last 5 writes sit in the unanchored tail until the next batch. Tampering with an *anchored* entry is what turns verification red.

Migrating from mem0

Already using mem0? examples/mem0_migration.py shows a complete round-trip: mem0 JSON export → MemTether Exchange v1 → live retrieval → back to mem0 format. No mem0 SDK required, bi-temporal fields honestly marked temporal_source="backfilled".

Performance (microbenchmark, n=200, local SQLite)

Operation p50 p95 p99
remember (insert) 28.7ms 34.6ms 117.8ms
search (SGM entity) 33.1ms 39.5ms 41.6ms
search (keyword) 32.2ms 35.0ms 135.0ms
correct (supersede) 50.8ms 54.7ms 54.7ms

Reproduce: python _dev/benchmarks/bench_latency.py --n 200

Documentation

Under the hood: supersession chains (corrections never delete), bi-temporal timestamps (when facts were true vs when the system learned them), human-adjudicated conflict resolution, and a hash-chained audit log designed with EU AI Act Article 12 record-keeping requirements in mind (not certified compliance) record-keeping requirements.

One physical SQLite database, shared by every AI client via file-level pointers. No cloud. No API fees. No sync daemon. Greppable, git-able, yours — and auditable.

Compared to mem0 (66.6K★), Zep/Graphiti (31.5K★), and agentmemory (29.2K★): those systems either overwrite or delete old values. MemTether's supersession chain preserves the full history with source attribution and Q-Value ranking. EAF retrieval: 75.7% strict on LongMemEval 500Q (paired delta +19.4pp, McNemar p=7.8e-7).

How MemTether compares

MemTether memora (731★) memtrace (486★) icarus (290★) mem0 (66K★)
Supersession chains (corrections don't delete) ✅ enforced ❌ ❌ ✅ ❌ overwrite
Evidence chain (tamper-evident, browser-verifiable) ✅ court CLI + zip ❌ ❌ ❌ ❌
Human conflict adjudication (decisions on record) ✅ conflicts CLI ❌ ❌ ❌ ❌
Bi-temporal (valid_from ≠ recorded_at) ✅ 100% coverage on fact rows ❌ ✅ on knowledge-graph edges (not per-fact rows) ❌ ❌
Source attribution (who wrote it, enforced) ✅ registry + reject ❌ ❌ ✅ provenance ❌
Bi-temporal (per-fact rows) ✅ ❌ ❌ ❌ ✅ graph edges only
Conflict detection (rule-based + human review) ✅ candidate generator ❌ ❌ ❌ ❌
MCP server ✅ ✅ ✅ ❌ ✅
23+ client adapters ✅ auto-detect ❌ ❌ ❌ ❌
Evaluation integrity framework ✅ 5 patterns ❌ ❌ ❌ ❌
CI: 9 jobs / 538 tests ✅ ? ? ? ✅
Language Python ? Rust ? Python

'Each cell reflects the feature's presence in the project's public documentation as of 2026-10-07. MemTether's differentiator is not any single feature — it's the combination of all governance dimensions in one local-first deployment.'

Artifact bundle with per-question records.

PyPI CI License

mcp-name: io.github.lanbass869-cell/memtether MCP Registry OpenSSF Best Practices

Project page · Install · Docs · Reproduce · 中文文档


Quick Start

pip install memtether -i https://pypi.org/simple/
memtether init    # creates DB + connects all detected AI clients

That's it. MemTether detects Claude Code, Cursor, Windsurf, Codex, Gemini CLI and 18 more clients on your machine, writes MCP config, and verifies.

China users: if pip install memtether fails with No matching distribution, the Tsinghua mirror may lag behind PyPI. Use: pip install memtether -i https://pypi.org/simple/

More install options
# One client at a time
memtether setup claude-code
memtether setup cursor
memtether setup gemini-cli    # run `memtether setup list` for all 23

# With semantic search (local embedding, no cloud):
pip install "memtether[vector]"          # 1. deps (chromadb, onnxruntime)
memtether download-models                # 2. weights (bge-m3-int8 ~560MB, or --profile bge-small-zh ~46MB)
python -m memsearch --rebuild            # 3. build the vector index
# Skip any of these and search gracefully degrades to keyword + BM25.

# With REST API server + web dashboard
pip install "memtether[server]"
memtether dashboard

# Docker
docker-compose up

> **Security note**: the REST API is unauthenticated unless you set MEMTETHER_API_KEY. Only expose port 8080 to trusted networks — on a shared machine, set the key in .env before docker-compose up.
> **`memtether init` caveat**: auto-detection works for clients in standard install paths. Clients in custom locations may be missed or falsely reported — use `memtether connect verify` to confirm, and see docs/ADAPTERS.md for manual MCP config.

Why MemTether

The one thing no other memory system does: corrections don't delete

# Monday: Claude Code writes
$ memtether remember "Deploy to port 8080" --source claude-code

# Wednesday: you correct it via Cursor
$ memtether correct fact-xxx "Deploy to port 9090" --reason "port changed"

# Friday: another agent searches
$ memtether search "deploy port" --list
  1. [fact] Deploy to port 9090 (active)          ← current truth
     Old "port 8080" is superseded, not deleted.
     Full chain: memtether timeline fact-xxx

Every memory has valid_from / valid_to (business time) + recorded_at / invalidated_at (system time). You can query "what did the system know on Tuesday?"

How it's different

MemTether engram mem0 agent-memory
Storage SQLite via file pointers SQLite (Go binary) Cloud API Markdown files
Supersession ✅ bi-temporal, never delete ❌ ⚠️ partial ✅
Source attribution ✅ every fact tagged ❌ ❌ ❌
Q-Value feedback ✅ used memories rank higher ❌ ❌ ❌
Poisoning defense ✅ OWASP LLM01/02/06 ❌ ⚠️ faithfulness check ❌
Cross-client ✅ file-level pointers (23 adapters) ✅ MCP ✅ API ✅ CLI
Cloud required ❌ optional ✅ ❌
Feature comparison vs cognee / zep / letta
Feature MemTether cognee zep letta Engram*
Local-first ✅ ❌ ❌ ⚠️ self-hosted ✅
Zero config ✅ ❌ (Neo4j) ❌ (Docker) ⚠️ ✅
Single file DB ✅ ❌ ❌ ❌ ✅
REST API ✅ (12 endpoints) ✅ ✅ ✅ ❌
MCP server ✅ ❌ ✅ ✅ ❌
Web dashboard ✅ ❌ ✅ ✅ ❌
Supersession chain ✅ ❌ ❌ ⚠️ ❌
Bi-temporal ✅ ❌ ❌ ❌ ✅
Source attribution ✅ ❌ ⚠️ ❌ ❌
Q-Value ranking ✅ ❌ ❌ ❌ ❌
Poisoning defense ✅ ❌ ❌ ❌ ❌
Export as markdown ✅ ❌ ❌ ❌ ✅
23 client adapters ✅ ❌ ❌ ❌ ❌
Governance layer ✅ ❌ ⚠️ ❌ ❌

Architecture

Claude Code ────┐                  ┌──── Cursor
                │   symlink /      │
Codex ──────────┤   junction       ├──── Windsurf
                │                  │
Gemini CLI ─────┤                  ├─── WorkBuddy
                └───────┬──────────┘
                        │
                        ▼
              ┌──────────────────┐
              │   memory.db      │  ← One physical SQLite
              │   (WAL mode)     │
              ├──────────────────┤
              │ FTS5 trigram     │  ← BM25 full-text
              │ ChromaDB + bge-m3│  ← Semantic (optional)
              │ RRF fusion       │  ← Multi-path merge
              │ 4-factor rerank  │  ← Z-score + sigmoid
              │ Supersession     │  ← Never delete
              │ Bi-temporal      │  ← T-axis + T'-axis
              │ Q-Value          │  ← Usage-based ranking
              │ Hubguard         │  ← Concurrent write lock
              │ Poisoning guard  │  ← OWASP LLM defense
              └──────────────────┘
Technical details
Component Technology Purpose
Database SQLite (WAL mode) Single-file, zero-config, cross-platform
Full-text FTS5 trigram + triggers O(1) BM25 search, SQL-level sync
Vector ChromaDB + bge-m3 (1024-dim) Semantic search, local embedding
Fusion Reciprocal Rank Fusion (K=60) Merge multi-path results
Re-ranking 4-factor (sem .45 + rec .25 + freq .05 + imp .10) Z-score + sigmoid
Governance Supersession + bi-temporal + conflict detection Never delete
Concurrency Hubguard (file lock + atomic write) Cross-process safe
Security memtether_guard (OWASP LLM01/02/06) Poisoning defense
API FastAPI REST (12 endpoints) + MCP server (4 tools) Any language
Packaging PyPI + Docker + 23 client adapters pip install memtether

Connect Your Clients

# All detected clients (recommended)
memtether init

# One at a time
memtether setup claude-code
memtether setup cursor
memtether setup windsurf
memtether setup codex

Supported (23): Claude Code, Claude Desktop, Cursor, Windsurf, VS Code, Zed, JetBrains, Cline, Roo Code, Kilo Code, Continue, Cody, Amazon Q, Gemini CLI, Neovim, Codex CLI, WorkBuddy (CN + Intl), CodeBuddy, ZCode, DSH, OpenClaw, Agents-Neutral


Memory Operations

memtether remember "User prefers dark theme" --source claude-code
memtether search "theme" --list        # L0: one-line + uid
memtether search "theme"               # Full content
memtether correct <uid> "Updated"      # Supersede, never delete
memtether timeline <uid>               # Audit chain
memtether stats
memtether export-md --out ./backup     # Export as markdown
memtether dashboard                    # Web UI

Benchmarks

LongMemEval (500 questions, full run, 2026-10-02)
Metric Score Notes
Strict match (global) 62.6% 209/334 applicable
LLM judge (global) 55.7% 264/474
Multi-session strict 48.8% 39/80
Multi-session LLM judge 60.0% 72/120
EAF 75.7% 253/334 — multi-session 32.5%→60.0%
Type n Strict LLM Judge
knowledge-update 78 76.6% 62.5%
multi-session 133 48.8% 60.0%
single-session-assistant 56 40.4% 41.1%
single-session-preference 30 N/A 43.3%
single-session-user 70 86.4% 85.7%
temporal-reasoning 133 60.7% 40.5%

Results use our own harness. Not directly comparable with mem0's reported numbers.

Test suite
Test Result
pytest 538 passed, 4 skipped (CI runs full tests/ directory)
hard_bench 62/62
e2e_verify 13/13
refuse_bench 26/26 (wordform gate; 09-25 calibration; known blind spot: same-form-different-attribute)
check_packaging ✅

Security

  • Poisoning defense: memtether_guard detects prompt injection, code execution, sensitive info (OWASP LLM01/02/06), 12 rules
  • Input validation: content ≤10K, type whitelist, source format, confidence range, scope whitelist
  • Scope isolation: shared / private / restricted
  • Concurrency: Hubguard file lock + atomic write (WAL mode)
  • SQL: All parameterized. No f-string SQL

Known Limitations

  1. tether_connect detect may falsely report "not connected" for same-source-different-path configs
  2. DSH deep customizations (cordis.patch.yml) cannot be safely rewritten — use plan to preview
  3. Semantic search requires optional deps (chromadb, onnxruntime) — without them, degrades to keyword search
  4. Windows-first. macOS/Linux should work but not fully tested
  5. Exchange adapters for mem0/zep are experimental — they require the corresponding library installed

REST API

memtether dashboard   # starts server + opens browser
# or: uvicorn api_server:app --port 8820

12 endpoints: /health /remember /search /stats /correct /retire /list /timeline/{uid} /absorb /qvalue /dashboard


Contributing

See CONTRIBUTING.md.

License

Apache-2.0


Star History

If MemTether helps you, please give it a ⭐ on GitHub — it helps other agents find it.

Troubleshooting

Symptom Fix
no AI client detected after memtether init Clients in non-standard paths need manual MCP config — see docs/ADAPTERS.md
database is locked during writes WAL mode is default; a long reader may hold the lock — retry after 5s (busy_timeout is set)
source not registered on write Open-source mode is fail-open; a registry file (agents.json) enforces attribution — add your client to agents.json or set MEM_SOURCE_FALLBACK
embedding search failed warning Optional chromadb/bge models missing — install pip install memtether[semantic] or ignore (keyword fallback works)
memory chain FAIL after manual edit Intentional: the audit hash chain detects direct DB modification. Restore from backup or run memtether court <uid> to inspect

Roadmap

See ROADMAP.md for planned work and explicit non-goals.

Metadata

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