Agents forget everything when the session ends. The people who needed to know never find out what they did.
CommonMind is the one memory they share — transactional, distributed, and engineered not to go down.
New here? → Start here · Live site · Build log · Developer spec · Architecture · Failure modes
- The problem
- What CommonMind is
- Why CockroachDB
- Why AWS serverless
- Architecture
- Data model
- The three agents
- The human interface
- Public and private memory
- Consistency and failure modes
- Security model
- Observability
- Quickstart
- Interface surface
- The ten principles
- Proof surfaces
- Editions
- Hackathon compliance
- Roadmap
- Repo layout
- Status and honesty policy
Two failures, and they compound.
Agents forget. Context dies with the session. An agent that spent forty minutes learning your codebase's auth quirks starts tomorrow knowing nothing. The industry's answer has been to stuff more into the context window, which is expensive, lossy, and still gone at the end of the turn.
Humans and agents don't share a memory. Agents emit a flood of events; people can't absorb a flood, so the person who needed to know doesn't. When an agent finally does need a human — "should I deploy this?" — it has no channel that carries enough context for the human to answer well, and no way to remember the answer next time.
Most memory products solve the first problem. CommonMind treats them as the same problem: if the memory is genuinely shared, the human's decision is just another memory the agent recalls.
| Situation | Without shared memory | With CommonMind |
|---|---|---|
| Agent resumes after a crash | Restarts from zero, redoes work | Recalls its own last-known state and continues |
| New engineer asks "how does auth work?" | Interrupts whoever knows | Queries the brain; gets the decision and its rationale |
| Agent hits a risky action | Acts anyway, or blocks forever | Asks a human; the answer is stored and reused |
| Two agents work the same problem | Duplicate or conflicting work | Coordinate by reading/writing one transactional log |
| A node dies mid-write | Partial state, torn memory | Row and embedding commit atomically or not at all |
A memory layer where CockroachDB is the system of record, not a cache in front of one.
capture → recall → act (with human approval) → improve
- Capture — an agent or person records what happened. The row and its embedding commit in one transaction.
- Recall — semantic search over everything captured, via CockroachDB's C-SPANN vector index.
- Act — the agent does safe work autonomously and stops for a human on consequential decisions.
- Improve — background consolidation scores novelty, extracts patterns, and reorganises memory so recall gets better over time.
What it is not: a RAG wrapper, a vector store bolted onto a chat app, or a notification service. The distinguishing claim is that the transactional memory log is also the coordination bus and the event source. Nothing polls. Nothing reconciles.
Because an agent whose memory goes offline doesn't degrade gracefully. It stops.
CockroachDB was built by people who hit this at Google first. Spencer Kimball and Peter Mattis worked on the Google File System team — Mattis later on Colossus, its successor — and Ben Darnell on Google Reader. They watched Google solve globally-distributed relational data with Spanner, hit the same wall again at their own startup, and in 2015 built the open-source answer. They named it after the animal that survives anything.
One range of CommonMind memory, replicated 3× and coordinated by Raft. Lose the leaseholder and the cluster re-elects, transfers the lease, and re-replicates — in seconds, with no operator action.
"Never goes down" is marketing. This is the engineering:
| Property | Guarantee |
|---|---|
| Replication | Every range replicated 3× by default across distinct nodes |
| Consensus | Raft — a write commits once a majority of replicas acknowledge |
| Survivable failures | (replication factor − 1) ÷ 2 → 3× survives one node; 5× survives two |
| Recovery | Detect → Raft re-election → lease transfer → re-replication, in seconds |
| Under partition | CP — below quorum a range goes unavailable rather than serving stale data |
| Isolation | Serializable by default |
The last two rows are why this database and not another. A memory layer that returns stale context is more dangerous than one that returns an error, because the agent will act on it with full confidence. We would rather an agent be told "memory is unavailable" than be told something that was true ten minutes ago.
This constrains our own demo. On a 3-node cluster we can kill exactly one node on camera. Killing two is not a CockroachDB failure, it's the documented quorum boundary. The kill-the-node video uses a 3-node cluster and kills one, or a 5-node cluster and kills two — stated explicitly either way.
CockroachDB indexes vectors with C-SPANN: a hierarchical K-means partition tree derived from Microsoft's SPANN, with SPFresh-style incremental updates and quantization ideas from Google's ScaNN.
It is not HNSW, and that matters for this workload. HNSW is an in-memory navigable graph — excellent at moderate scale, but the graph doesn't shard cleanly across nodes and degrades under sustained inserts and deletes until it's rebuilt. An agent memory is nothing but sustained writes. C-SPANN partitions shard onto CockroachDB ranges like any other data, and new vectors are searchable immediately with no rebuild.
⚠️ Contributors: pgvector syntax (USING hnsw (...)) will not run on CockroachDB. UseCREATE VECTOR INDEX.
This distinction has already cost us one bug, so it's worth being precise.
CockroachDB is not built on, forked from, or code-derived from PostgreSQL. It's an independently developed distributed database, written in Go and modelled on Spanner. What it does is implement the PostgreSQL wire protocol (pgwire v3.0) and the majority of Postgres syntax, deliberately, so existing tooling works.
Why we depend on pg |
The node-postgres driver speaks pgwire, so it talks to CockroachDB unmodified |
Why the DSN says postgresql:// |
Same reason — it's the wire protocol's scheme, on CockroachDB's port 26257, not Postgres' 5432 |
| Where compatibility stops | Anything hard to implement in a distributed system: CREATE DOMAIN, range types, XML functions, advisory locks — and pgvector |
The practical rule: treat Postgres knowledge as a useful prior, never as an authority. When a Postgres answer and a CockroachDB doc disagree, the CockroachDB doc wins. Our USING hnsw bug came from exactly this — Postgres-with-pgvector indexes vectors that way, CockroachDB does not implement HNSW at all, and "it's Postgres compatible" made the wrong answer look right.
CREATE VECTOR INDEX memory_embeddings_cspann
ON memory_embeddings (embedding vector_cosine_ops);Every component scales to zero, so an idle memory layer costs nothing and a busy one costs per invocation. The AWS Free Tier covers the entire development path.
The database is both the state store and the event source — a changefeed on the committed row is the only trigger the push pipeline needs.
The database is the event source. That single decision deletes an entire category of infrastructure. There's no message broker to operate, no outbox table, no reconciliation job, and no dual-write bug — because nothing publishes an event separately from committing the row. The commit is the event.
Everything else follows from it.
| Layer | Choice | What it replaces, and why ours wins |
|---|---|---|
| Memory | CockroachDB Cloud Basic (serverless, on AWS) | vs. a dedicated Standard cluster at ~$120–130/mo — which alone would exceed the entire $20/employee price point. Basic is RU-metered and scales to zero |
| Compute | AWS Lambda | vs. ECS/EKS — containers you size, patch, and pay for while idle. Lambda is 1M requests/month free, permanently |
| HTTP front | Lambda Function URLs | vs. API Gateway — a separate service with routes, stages and integrations to configure. We need an HTTPS endpoint, not a gateway |
| Embeddings | Bedrock, Titan v2 @ 1024 | vs. a SageMaker endpoint, which bills while idle — the opposite of serverless. vs. OpenAI, which isn't AWS and fails the requirement outright |
| Fanout | SNS → SQS + DLQ | vs. Lambda subscribed directly to SNS, which has no retry buffer and no dead-letter — one failed push becomes a permanently lost notification |
| Artifacts | S3 | Standard, boring, correct |
Explicitly not used: DynamoDB. It's a second database, and the thesis here is that CockroachDB is the system of record for agentic memory. A second store means a second source of truth, and something has to reconcile them. It fills no gap.
Nothing costs anything at rest. Every layer scales to zero, so an idle tenant is ~free and a busy one bills per invocation. That's what makes $20/employee/month work at 80–90% gross margin. The AWS Free Tier covers Lambda (1M requests/mo, always free), SNS (1M publishes), SQS (1M requests) and S3 (5 GB). Bedrock isn't free-tier, but Titan v2 at $0.02 per million input tokens makes embedding effectively free at demo scale.
There is exactly one source of truth. Memory durability never depends on the delivery path. A push can fail, retry, or be dropped entirely and the memory is still correct — it was committed before anything downstream knew it existed.
Every hop fails safely. Bedrock down → capture fails closed, no row without its embedding. Lambda down → SQS retries, then dead-letters. Changefeed lagging → the push is late, not lost. The only component whose failure would cost data is CockroachDB, which is the one component engineered specifically not to.
Why not a queue-first design? Because the changefeed is the queue, and it's transactional. Publishing to a queue from application code reintroduces the dual-write problem: a row committed but its event lost, or an event emitted for a transaction that rolled back. CDC off the committed row makes that class of bug unrepresentable.
Measured, not modeled. The <50ms figure was a database-side estimate, never reproduced end-to-end — so it's gone. In its place, 15 real recall requests and 10 real capture requests through the actual deployed path (browser → Cloudflare edge → Cloudflare Tunnel → CockroachDB): recall runs 170–308ms (median 213ms), capture 286–330ms warm, ~700ms on a cold start. Slower than the old claim, and real — which is the whole point of the honesty policy below.
This is the core guarantee, and every design decision defers to it:
A memory record and its embedding commit in the same transaction.
BEGIN;
INSERT INTO memory_records (entity_type, content)
VALUES ($1, $2) RETURNING id;
INSERT INTO memory_embeddings (entity_type, entity_id, embedding)
VALUES ($1, $id, $3::vector);
COMMIT;There is no window in which something happened but isn't yet retrievable. Consolidation workers and the CDC pipeline read only from these transactional tables, so no consumer can observe a half-written memory. Any PR that splits these writes is wrong regardless of how much faster it is.
Capture: agent → Lambda API → Bedrock (embed) → CockroachDB (one txn) → changefeed → SNS → SQS → Lambda fanout → push target
Recall: agent → Lambda API → Bedrock (embed query) → C-SPANN nearest-neighbour search → joined rows → agent
Approve: agent requests → notification row committed → push → human decides → decision committed as a new memory → agent resumes with it in context
For the agent-role view of the same system — Memory Agent, Operator Agent and Dream-Weaver against the CockroachDB tables and AWS services — see assets/architecture.svg. Both diagrams agree on the write path: memory_records is the captured row, matching src/memory/repository.ts.
Full DDL in src/db/schema.sql. The memory core:
| Table | Purpose | Notes |
|---|---|---|
memory_records |
What happened | The durable content |
memory_embeddings |
Its vector | VECTOR(n), C-SPANN indexed, entity_id indexed for the recall join |
memory_consolidations |
Dream-weaver output | Patterns, digests, surprise scores |
memory_events |
Changefeed source | PK is unique_rowid(), never SERIAL |
notifications |
Agent → human milestones | Idempotency-keyed, with response state machine |
live_activities |
Stateful cards | Optimistic concurrency via sequence |
services / devices |
Tenancy and push targets |
Two schema decisions worth calling out:
Sequential primary keys are banned. memory_events uses unique_rowid(), not BIGSERIAL. A monotonic PK funnels every insert into a single range and creates a write hotspot — the classic CockroachDB anti-pattern, and memory_events is our hottest write path. This is the difference between a system that scales horizontally and one that only claims to.
Vector dimension is VECTOR(1024) — Titan v2's native default, decided Aug 4. The schema originally said 768 — a dimension no Bedrock model emits, so it had to move.
We chose Amazon Titan Text Embeddings V2 at 1024 over the alternatives:
| Option | Dims | Verdict |
|---|---|---|
| Titan v2 (default) | 1024 | ✅ Retrieval-optimised second generation; $0.02 / M input tokens |
| Titan v2 (reduced) | 512 / 256 | Matryoshka truncations retaining ~99% / ~97% recall — a real optimisation, but after submission |
| Titan v1 | 1536 | ❌ 5× the token price of v2, ~33% larger index, not retrieval-optimised |
At 4 KB per vector, storage isn't a constraint at our scale, and the Dream-Weaver's "measurably better over time" claim needs a clean quality baseline rather than a truncation chosen for storage we don't need.
| Agent | Responsibility | Constraint |
|---|---|---|
| Memory Agent | Capture and recall | Never writes a row without its embedding |
| Operator Agent | Acts on memory | Autonomous on safe work; stops for a human on consequential decisions |
| Dream-Weaver | Consolidation | Runs in the background; reads only committed rows; never mutates source memories |
Agents coordinate by reading and writing shared memory, not by messaging each other. The transactional log is the coordination bus, which means coordination is auditable by construction.
Agents emit a flood. People can't absorb a flood. Most of what an agent does is recorded silently and never needs a human at all. The exception is the genuinely consequential step:
agent requests approval → human decides (approve / edit / deny), via CLI or MCP → agent resumes → the decision itself becomes memory
Response kinds: approval, yes_no, text_reply, thread_question. The exchange persists in the same memory layer as everything else — recallable and auditable. The decision itself becomes memory, so the next call of that shape is faster and, eventually, unnecessary.
On the horizon, tracked in the build log: a real-time push layer (a doorbell, not a pager) on top of this — three alert classes (Silent / Alert / Priority) delivering to a phone the instant a decision is needed, instead of the human checking in. SNS + SQS + DLQ are provisioned in AWS today; the CockroachDB changefeed and Lambda bridge that would carry live traffic through them are the last mile.
Every person and every agent contributes to one shared datastore, but contribution is not surveillance.
| Visibility | Indexed | |
|---|---|---|
| Public | Teammates and agents; searchable by everyone | Yes — grows the company index |
| Private | The contributor only | Never added to the company index |
Contribute freely. The brain grows from everyone, and everyone controls their footprint.
This is a hard boundary in the data model, not a UI filter: private rows are excluded from the shared index at write time, so a recall query cannot surface them regardless of who asks.
What actually happens when each component fails:
| Failure | Behaviour | Data loss |
|---|---|---|
| One node dies (RF=3) | Raft re-elects, lease transfers, re-replication starts; reads and writes continue | None |
| Majority lost | Range unavailable; writes rejected | None — refuses rather than diverging |
| Bedrock unavailable | Capture fails closed; no row without its embedding | None — the transaction rolls back |
| Lambda fanout fails (designed; changefeed bridge not yet carrying traffic) | SQS retries, then DLQ; memory already committed | None — push is retryable, memory is durable |
| Changefeed lags (designed; not yet wired) | Push is late; recall unaffected | None |
| Human never answers | Approval expires at expires_at; agent takes the safe path |
None |
| Two agents write the same key | Serializable isolation; one retries | None |
The invariant across every row: memory durability never depends on the delivery path. A push can fail, be retried, or be dropped entirely and the memory is still correct.
| Concern | Approach |
|---|---|
| Tenancy | owner_id scoping per row; org namespaces |
| Auth | Webhook token per service, or bearer token |
| Secrets | Environment only; .env git-ignored; no credentials in source |
| Private memory | Per-contributor private rows are never added to the shared index |
| Audit | Every write is an event row — who, what, when, which agent |
| Least privilege | MCP server exposes read-only introspection by default |
| Transport | TLS to the cluster; sslmode enforced outside dev |
Because "did the agent actually remember?" has to be answerable.
- Capture rate — writes/sec by agent and by entity type
- Recall quality — similarity score distribution; queries returning nothing
- Approval latency — request → human decision, the one humans feel
- Changefeed lag — commit → push delivered
- Brain health — which people and agents are actively contributing, so nothing important goes quiet
- Consolidation gain — recall quality before vs after dream-weaver runs; the "memory improves itself" claim has to be measurable or it gets cut
Prerequisites: Node 20+, CockroachDB v25.2+ (vector indexes), optional AWS credentials for Bedrock.
git clone https://github.com/LandCruiserWorld/commonmind.git
cd commonmind
npm install
cp .env.example .env # set COCKROACH_DB_URL
cockroach start-single-node --insecure --listen-addr=localhost:26257 &
cockroach sql --insecure -e "CREATE DATABASE commonmind;"
cockroach sql --insecure --database commonmind < src/db/schema.sql
npm run check # type-check
npm testThe front door is one command; the target shape:
npm install -g commonmind
commonmind connect claude # register the MCP server / capture hooks
commonmind save "chose Raft over Paxos — simpler membership changes"
commonmind ask "why did we pick Raft?"
commonmind ask --approval "deploy 8e7fc2a to production?"One MCP server covers every agent CLI — Claude Code, Cursor, Codex, opencode — exposing memory.capture, memory.recall, memory.ask, memory.approve, memory.note. No per-app plugins.
Carried on the landing page as machine-readable JSON-LD (#commonmind-values) so agents building here can read them.
| 1 Memory is the product | 6 One core, any product |
| 2 Memory must never go down | 7 Brain health, not timecard |
| 3 Bridge, don't flood | 8 The front door matters |
| 4 Milestones, not noise | 9 Memory improves itself |
| 5 Human decides, agent executes | 10 Kill the node, memory survives |
Built for the CockroachDB × AWS Hackathon — Build with Agentic Memory. Rules require two CockroachDB tools and one AWS service.
| CockroachDB tool | How we use it |
|---|---|
| Distributed Vector Indexing | C-SPANN over memory_embeddings for recall and surprise scoring |
| Managed MCP Server | One server so any agent CLI reads/writes memory — no per-app plugins |
| ccloud CLI | A memory-ops agent provisions clusters, takes backups, configures RBAC |
| Agent Skills Repo | commonmind-query, commonmind-approve, commonmind-consolidate |
| Changefeeds (CDC) | Beyond the required list — the transactional event stream driving push |
We exceed the 2-of-4 requirement: all four required CockroachDB tools are used, plus changefeeds beyond the list.
| AWS service | What the agent actually does with it |
|---|---|
| Amazon Bedrock | Titan Text Embeddings V2 (1024-dim) embeds every capture and query; recall/summarization LLM answers from the memory layer |
| AWS Lambda | Serverless agent execution behind Lambda Function URLs — capture, recall, and approval handlers scale to zero |
| Amazon SNS → SQS + DLQ | Changefeed fanout for the push pipeline, with retry and dead-lettering so no notification is lost |
| Amazon S3 | Artifact/document storage — exported memory snapshots and runbook sources |
Full rationale in Why AWS serverless.
| Devpost requirement | Status | Proof location |
|---|---|---|
| Public open-source repo | ✅ | github.com/LandCruiserWorld/commonmind (public, Apache-2.0, license visible in About) |
| All necessary source code | ✅ | src/ |
| Clear README documentation | ✅ | this file |
| Dependencies declared | ✅ | package.json, package-lock.json |
| Example configuration | ✅ | .env.example |
| Setup + run instructions | ✅ | Quickstart |
| Functional demo app URL | ✅ | https://commonmind.agent9.dev |
| Video < 3 min, CockroachDB memory layer at work | 🟡 | recording — BUILD_LOG |
| 2× CockroachDB tools (we use 4 + changefeeds) | ✅ | table above |
| 1× AWS service (we use 4) | ✅ | table above |
| Architectural diagram | ✅ | assets/images/aws-serverless-architecture.svg + Architecture |
One memory core, four real, unrelated products — connected live, not staged for the demo. The point of building four is that a memory layer which only works for one workload isn't a memory layer, it's a feature.
| Case study | Integration | What it proves |
|---|---|---|
| Ocean Dreams (Three.js game) | The creature remembers player behaviour across sessions — 600+ real captures today | Behaviour visibly changes based on what it remembers about you |
| Solana trading platform (Python, on a Raspberry Pi over Tailscale) | Every trade decision and its rationale captured automatically; a risky entry stops for explicit approval via CLI/MCP instead of acting alone | Kill the node on camera — the bot keeps its context, no data loss |
| Finestra (AI agent on a second Raspberry Pi) | Answers a real email, its response captured to the same shared memory | An agent with its own hardware, its own inbox, sharing the one brain |
| Dev-team coding sessions | Capture hooks on Claude Code, Antigravity, opencode, Kimi K3, Qwen | A new hire asks the brain, not the person who knows |
Any two of these can share recall on purpose — flip a toggle in the dashboard and Trading Bot and Finestra start recalling each other's memory. Off by default; nothing shares unless you turn it on.
| Self-hosted | Premium | Enterprise | |
|---|---|---|---|
| Price | $0 forever | Custom | |
| Memory core — capture, recall, act, consolidate | ✅ | ✅ | ✅ |
| Integrations, MCP server, web inbox | ✅ | ✅ | ✅ |
| Runs on | Your own CockroachDB | Managed serverless AWS | On-prem / VPC |
| Uptime | Yours | 99% monitored | Custom SLA |
| Support | Community | Self-serve onboarding | Dedicated engineer, 24/7 |
Open source is free forever and always will be — self-host it, embed it in a product, ship it. Premium is for teams who'd rather not run a database — free during launch, no card required: cutting-edge memory on resilient AWS + CockroachDB infrastructure, on us.
Deadline Aug 18, 2026, 5:00 PM EDT. Dates from the build log:
| Date | Deliverable |
|---|---|
| Aug 6 | create-commonmind scaffold + CLI |
| Aug 9 | Capture → recall end-to-end against a live cluster |
| Aug 12 | Trading bot on Raspberry Pi + Tailscale |
| Aug 14 | Ocean Dreams integration |
| Aug 16 | Agents layer + resilience |
| Aug 17 | Demo video + kill-the-node |
| Aug 18 | Submission |
Live status and open decisions: docs/BUILD_LOG.md.
src/
config.ts env + defaults
db.ts pool + transaction helper
memory/
repository.ts atomic write + recall
types.ts domain types
db/schema.sql CockroachDB DDL
docs/
BUILD_LOG.md live status, decisions, open questions
DEVELOPER_SPEC.md schema, API contract, components
MASTER_DEVELOPER_DOC.md
STRATEGIC_PLAN.md
agents/AGENTS.md rules for coding agents in this repo
site/index.html landing page + JSON-LD core values (single copy)
assets/images/ cover, architecture and resilience diagrams
tests/
This repo is under active build. What's true today:
| ✅ Done | Schema, TypeScript memory core, core values + JSON-LD, landing page, architecture, MCP server (capture · recall · ask · approve · note), approval round-trip, capture → recall against a live cluster (CLI + HTTP), account auth + self-serve project keys, real network-map dashboard, end-to-end latency measured |
| 🟡 In build | npm install -g commonmind front door, trading-bot integration (live on the platform, not yet demo-recorded), kill-the-node capture |
| ⏳ Next | AWS event pipeline — SNS topic + SQS queue + DLQ are provisioned and wired in us-east-2 today; the Lambda bridge and the CockroachDB CREATE CHANGEFEED that would put real traffic through them are the next step, not yet done. Also: multi-node resilience benchmark, demo video |
| ⬜ Later | Dream-weaver consolidation (spec) |
Performance figures on the landing page are measurements, not design targets — the <50ms estimate is gone, replaced by 15 real recall requests and 10 real capture requests against the actual deployed path (see Why AWS serverless). We would rather show one measured number than five aspirational ones — a claim we can't reproduce on demand is a claim a judge can dismantle.