# Sources — Durable Agent Runtimes & Harness Engineering

> Part of [[durable-agent-runtime/index|Durable Agent Runtimes & Harness Engineering]]

Full reference list for the research topic. One line per source: what it is, why it matters.

## Amp Orbs (remote sandbox + durable agent loop)

- [Agents in Orbs (Amp news, 2026-06-30)](https://ampcode.com/news/agents-in-orbs) — launch announcement. Orbs = machines where agents run without supervision; fresh orb per thread with code/plugins/tools; 32GB/16-core default, $1.32/hr, billed by the minute, auto-pause after 5 min idle.
- [Putting an Agent in an Orb (Amp note, 2026-07-02)](https://ampcode.com/notes/putting-an-agent-in-an-orb) — the deep-dive: `.agents/setup` + `.agents/resume` repo hooks, snapshot reuse up to 24h, dev-server skill (`ensure-dev-server.sh`), `/__dev` auth endpoints, `.amp/dev-ports.json`, `.amp/in/` logs, 41 AGENTS.md files.
- [What I Want to Tell You About Orbs (Amp note, 2026-08-04)](https://ampcode.com/notes/what-i-want-to-tell-you-about-orbs) — philosophy/experience piece. "Ingredients": secure sandbox, scale to zero, ephemeral, durable agent loop, controllable from web/phone/desktop, portals, multiplayer, automations. Evidence-first workflow: agents must produce proof (screenshots, videos).
- [Orbs manual (Amp docs)](https://ampcode.com/manual/orbs) — full spec: orb sizes, billing, `.agents/setup`/`.agents/resume`/`.amp/services.yaml`/portals, webhooks (event-driven orbs), OIDC workload identity (`amp orb id-token`), secrets hierarchy (personal > project > workspace).
- [Amp Security Reference](https://ampcode.com/security) — the architecture disclosure: Amp Client (CLI) + Amp Server (GCP multi-tenant, PostgreSQL thread storage) + **e2b** for sandbox compute; providers (Anthropic/OpenAI/xAI/Meta/Gemini/Bedrock/Baseten/Fireworks for inference, WorkOS auth, Stripe billing). No self-hosted deployment offered.

## Durable objects / durable execution

- [denoland/celld (GitHub)](https://github.com/denoland/celld) — self-hosted, distributed Durable Objects. Each object is its own SQLite DB, replicated to an S3-compatible bucket; nodes coordinate through the bucket with no control plane/consensus. V8-embedded, runs Wrangler bundles. Idle cells hibernate. By Deno Land (ry@deno.com). ~222★, Apache-2.0.
- [rivet-dev/rivet (GitHub)](https://github.com/rivet-dev/rivet) — Rivet Actors: long-running lightweight processes for stateful workloads. In-memory state + automatic persistence (SQLite/BYO DB), ~20ms cold start, ~0.6KB memory/instance, scale to zero, WebSockets/queues/workflows/scheduling, global edge. Self-host (single Rust binary) or cloud. ~5.8k★, Apache-2.0. Engine sub-components: Pegboard (orchestrator), Gasoline (durable execution), Guard (traffic proxy), Epoxy (multi-region KV, EPaxos).
- [celld.dev docs](https://celld.dev/docs) — official docs for celld (deployment, limitations, security pages).

## Sandbox / VM runtimes

- [kernel/hypeman (GitHub)](https://github.com/kernel/hypeman) — multi-hypervisor VM runtime for OCI images: Cloud Hypervisor, Firecracker, QEMU on Linux; Apple Virtualization.framework on macOS. Docker-compatible CLI (`run`, `exec`, `ps`, `logs`), standby/restore (snapshot VM to disk, resume in ms), built-in ingress/TLS/subdomain routing, GPU passthrough, remote JWT-authenticated API. ~303★, MIT.
- [e2b-dev/infra (GitHub)](https://github.com/e2b-dev/infra) — infrastructure powering E2B Cloud: Firecracker-based sandbox VMs for AI agents, template system, snapshot cold starts (sub-30ms). Open source; the substrate Amp orbs run on (per Amp's security reference). Also E2B docs: [e2b.dev](https://e2b.dev/docs).
- [Spheron guide: E2B vs Daytona vs Firecracker (2026)](https://www.spheron.network/blog/ai-agent-code-execution-sandbox-e2b-daytona-firecracker/) — sandbox architecture comparison: E2B managed (CPU-only, snapshot cold starts), Daytona, Firecracker. Snapshot-restore + sandbox pooling math for cold-start latency.

## Durable harness library — pi-durable

Researched 2026-10-20 against `main` (`48c8f32`) and published `1.3.0`; full write-up in [[durable-agent-runtime/pi-durable|pi-durable]].

- [packages/durable README](https://github.com/earendil-works/pi/blob/main/packages/durable/README.md) — API tour: concepts, persist/resume, extensions, tools, code mode, settings, environment, compaction, child tasks, storage, errors. Documents some unreleased features (durable sleeps, `onWake`, crash-loop guard) not present in 1.3.0.
- [packages/durable docs/spec.md](https://github.com/earendil-works/pi/blob/main/packages/durable/docs/spec.md) — normative spec (~5.6k lines). Key sections: §1 invariants, §5.2 effect sandwich, §5.5 structured concurrency, §8.3 generation recovery, §8.4 tool replay policy, §12 API footguns, §13 non-goals.
- [packages/durable CHANGELOG](https://github.com/earendil-works/pi/blob/main/packages/durable/CHANGELOG.md) — 1.0.0 (2026-10-01) through 1.3.0 (2026-10-15); Unreleased has breaking changes (removes `TaskRuntime.sleep()`, SQLite schema v2 with no rollback).
- [packages/durable package.json](https://github.com/earendil-works/pi/blob/main/packages/durable/package.json) — v1.3.0, MIT, Node >= 22.19; deps: pi-ai, chord, pi-codemode, pi-telemetry, TypeBox, Photon, diff.
- [packages/chord README](https://github.com/earendil-works/pi/blob/main/packages/chord/README.md) — document-state substrate: objects at addresses, observable JSON, delta tracking, hot reload, SQLite adapters.
- [Earendil, "Pi Durable" launch post (2026-10-01)](https://earendil.com/posts/pi-durable/) — vendor positioning and architecture tour; claims ~15k LOC excluding tests, "runs anywhere there is a JavaScript runtime", multi-client/multiplayer design; FAQ says a Rust port is possible but not planned.
- [npm: @earendil-works/pi-durable](https://www.npmjs.com/package/@earendil-works/pi-durable) — first publish 2026-09-19; 16 versions; 1.3.0 latest as of 2026-10-20; npm API reports 387,665 downloads for the week ending 2026-10-18.
- [GitHub: earendil-works/pi](https://github.com/earendil-works/pi) — monorepo metadata at 2026-10-20: 116,619 stars, 14,877 forks, MIT; `packages/durable` has 175 path commits (oldest API result 2026-09-18), 1.0.0 released 2026-10-01.

Empirical (this research, 2026-10-20): installed 1.3.0 under Node 22.22.2; ran faux-provider chat, `SIGKILL` mid-task with/without `runtime.memo`, `SIGKILL` mid-tool for `replay: "safe"` vs default `unsafe`, and dumped the SQLite schema. Results and caveats (including a cold-open `waitForTask` race) are in [[durable-agent-runtime/pi-durable|pi-durable]].

## Harness engineering / agent-as-library

- [gakonst/nanocodex (GitHub)](https://github.com/gakonst/nanocodex) — library-first Rust reimplementation of the Codex harness ("blazing-fast, minimal, library-first"). Typed turns/tool registry/event streams/steering/cancellation/forks over the OpenAI Responses WebSocket API. Agent session lives in your process; no app server or durable control plane. Crates: facade, agent lifecycle, typed OpenAI boundary, tools (shell/Code Mode/MCP), observability (OTel), experimental voice + VM-backed tools. Thin CLI/TUI, Python, Node/WASM, React consumers. Auth shares `~/.codex/auth.json`.
- [tact (github.com/clabby/tact)](https://github.com/clabby/tact) — a terminal interface for nanocodex, launched Jul 2026; browser-based `/review` interface (agent-authored visual code review). Proof of the build-your-own-agent-on-nanocodex loop.
- [Cloudflare: Code Mode — the better way to use MCP (blog, 2025-09-26)](https://blog.cloudflare.com/code-mode/) — converts MCP tool schemas into a TypeScript API and asks the LLM to write code that calls the API, instead of presenting tools directly. Run in a sandboxed V8 isolate via the Worker Loader API; no containers. Finding: LLMs are much better at writing code than at synthetic tool-call tokens; avoids copying intermediate tool results back through the context.
- [Cloudflare Agents SDK codemode docs](https://github.com/cloudflare/agents/blob/main/docs/codemode.md) — the codemode helper + worker loader usage.
- [Prime Intellect: Recursive Language Models (blog, 2026-01-01)](https://www.primeintellect.ai/blog/rlm) — RLM paradigm: persistent Python REPL as the model's only tool, context as a variable, sub-LLM calls as functions. Related arXiv: 2512.24601 (Recursive Language Models), 2605.09998 (Continual Harness: Online Adaptation for Self-Improving Foundation Agents).

## Context from our own work

- Buzz thread origin: `buzz://d8a718be-031f-4a6e-9f5c-a55466641654/91604ae52f7fc33d6e43543f3b7c355f65f353d4a6bc820b6dd8e8d0fd70f2ae` (Amp Orbs research) and the triggering event for this topic.
- Workspace note: `RESEARCH/AMP_ORBS_REMOTE_DEV.md` — Amp Orbs deep research with system-design follow-up (E2B substrate, lifecycle, mapping to our stack).
- Session research on nanocodex (2026-07-31): library-first Rust SDK, vs Codex/pi/OpenCode positioning, reviewer-harness relevance.
- clan-private: `machines/hermes-vm/configuration.nix` (hermes-vm host config), `modules/dev/containers.nix` (rootless podman enabled), `services/buzz/` (Buzz relay/gateway/agents), herdr (persistent PTY / tmux replacement).