bare-operating-system/handbook/01-introduction.md

# Chapter 1 — Introduction: what “Bare OS” is

**Time to read:** about 8 minutes. **Prerequisites:** none; [Preface](00-preface.md) first if you want the thesis in essay form.

If you have only a minute: **Bare operating system** is a tiny **Unix-flavored environment** whose root filesystem is a **Hyperdrive** replicated from peers. A **seeder** publishes that drive and a **512-byte MBR** over **Hyperswarm**; a **booter** joins the swarm, downloads the image, mounts a **second** Hyperdrive for **per-user mutable state**, and runs JavaScript “kernel” and `/bin` scripts inside a **Bare** or **Node** runtime.

The rest of this chapter sets vocabulary straight—without it, the architecture diagrams in [Chapter 2](02-blueprints.md) will not stick.

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## From `git clone` to a first prompt (story, not a runbook)

Imagine two terminals on the same machine. In one you run the **seeder**: it loads the **`kernel/`** tree into a **system Hyperdrive**, writes a **512-byte MBR** (magic **`BIOS`**, embedded public keys), and joins **Hyperswarm** on the project topic plus the drive’s **discovery key**. In the other you run the **booter**: it joins the topic, finds a peer, opens a **Protomux** channel, reads **block 0**, parses the MBR, opens the system drive by key, creates your **personal** drive, and hands off to **`/boot/init.js`**. You see a line prompt; everything “POSIX” after that is the booter’s **VFS** and **shell** simulating a machine.

Exact commands, env vars, and Pear workflows live in [Chapter 7 — Operations](07-operations-and-development.md) and the root [README.md](../README.md). This paragraph is only the **narrative spine**.

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## The problem this project explores

Traditional OS images live on block devices or tarball layers. Here, the **image is a Merkle tree** you can **address by key** and **replicate live**. Peers do not hand you a `.iso`; they help you **fill in** the same Hyperdrive from the same discovery key.

That raises three design questions this repo answers in code:

1. **Discovery** — How does a fresh node find _someone_ who has block 0 (the MBR) and the drive root?
2. **Separation of concerns** — What is **immutable-ish OS** vs **mutable per-device home**?
3. **Execution model** — What runs in the host process vs what is “inside” the simulated POSIX surface?

Bare OS picks: **one swarm topic** for the project, **Protomux** channels for control + replication, **two Hyperdrives** (system + personal), and **AsyncFunction-loaded JS** for kernel and utilities.

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## Key vocabulary

| Term               | Meaning here                                                                                      |
| ------------------ | ------------------------------------------------------------------------------------------------- |
| **System drive**   | Hyperdrive containing `/boot/init.js`, `/bin`, `/etc` — replicated from the seeder image          |
| **Personal drive** | Separate Hyperdrive (Corestore namespace) for `$HOME`, `/.bare`, cron, logs                       |
| **MBR**            | 512 bytes: magic `BIOS` + embedded Hyperdrive **public keys** (primary + optional failover)       |
| **Kernel**         | `/boot/init.js` — `async function start(ctx)`; not a microkernel, a **session loop**              |
| **/bin**           | Small JS programs (`async function run(ctx, argv)`) built from **bare-os-coreutils** — includes a TTY editor (**`edit`**, **`nano`**) and usual POSIX-style tools |
| **VFS**            | Booter-provided path layer: routes paths under `$HOME` to the **personal** drive, else **system** |
| **ctx**            | Context object passed to kernel and commands: `vfs`, `console`, `execLine`, identity hooks, etc.  |
| **Guest**          | Default session before `login` — predictable `HOME=/home/guest`, no Ed25519 identity              |
| **HDMS**           | “Hyperdrive management” — optional extra drives mounted under `/mnt` after unlock                 |

### Holepunch stack (first-use definitions)

Use these names consistently across docs:

- **Hyperdrive** — Append-only, sparse-friendly filesystem identified by a public key; good for a shared OS tree.
- **Hyperswarm** — DHT-style peer discovery; Bare OS uses a **topic** (`bare-os-v1`) and **drive discovery keys**.
- **Protomux** — Multiplexes logical channels on one encrypted stream; the **`bare-os-v1`** channel carries MBR reads and replication.
- **Corestore** — Storage backend that holds Hyperdrive cores; seeder and booter use separate store paths.
- **Bare** — Minimal JavaScript runtime; **Pear** wraps Bare for distributable apps (the seeder and booter are Pear apps).

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## Why Hyperdrive and Hyperswarm

**Hyperdrive** gives you a **single-writer** (per key) log-backed filesystem with **deterministic** reads and **sparse** replication—good for an OS tree that many nodes can share.

**Hyperswarm** gives you **topic-based** and **discovery-key-based** peer finding. The seeder joins both the **bare-os-v1 topic** (so booters find _some_ peer) and the **drive discovery key** (so Hyperdrive replication completes).

You do not need to agree with every product choice to read the code: the handbook describes **what the repo does**, not whether it is the only way to build a P2P OS.

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## Relationship to Pear and Bare

- **Bare** is a minimal JavaScript runtime used by **Pear** apps.
- Both **seeder** and **booter** are **Pear applications** (`pear` field in `package.json`) and can run under **`node index.js`** for development.
- **brittle-bare** vs **brittle-node** split in tests reflects native addons (e.g. identity crypto) that only load on Bare.

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## Where to go next

- Essay-length thesis: [Preface](00-preface.md)
- Big picture: [Chapter 2 — Blueprints](02-blueprints.md)
- Wire protocol: [Chapter 3](03-protocol-and-disk.md)
- Day-to-day hacking: [Chapter 7](07-operations-and-development.md)

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**Next:** [Chapter 2 — Blueprints](02-blueprints.md)

**Related:** [Handbook home](README.md) · [Kernel extensions](../docs/reference/kernel-extensions.md) · [CHANGELOG — ctx API](../packages/bare-os-booter/CHANGELOG.md)

_Experimental research software, not a production OS. Apache-2.0 — [LICENSE](../LICENSE)._