# `gno.land/r/moul/x/plan9/dev/v0`

**The chain as a Plan 9 device tree.** Everything a realm normally reaches
through an import of `chain/runtime` is published here as a file instead, so it
can be read, listed, bound and unioned like anything else.

```
cat /dev/sysname     the chain id
cat /dev/height      the block height
cat /dev/session     what a delegated key is allowed to touch
```

| device | contents |
|---|---|
| `caller` | pkgpath of the realm that crossed into this read |
| `domain` | the chain domain |
| `drivers` | the table itself |
| `height` | current block height |
| `null` | always empty |
| `random` | sha256 of chain id and height, hex; block-deterministic, **not** unpredictable |
| `session` | the calling key's session scope, one `AllowPath` per line |
| `sysname` | the chain id |
| `time` | block time, RFC3339 |
| `user` | the origin caller's address |
| `zero` | endless NUL bytes; reads exactly what you ask for |

A device is code, not storage: reading `/dev/height` runs a function, so it is
never stale.

## The cross-realm mount

This realm posts its tree to
[`r/moul/x/plan9/ns`](../../../../../r/moul/x/plan9/ns/v0)'s `/srv` at deploy
time, so any account can bind it into their own namespace and nobody has to
import this realm to use it:

```
bind /srv/dev /dev
```

That is the mechanism the whole experiment turns on: an interface value
published by one realm, stored by another, and called back later from a
read-only `Render`. Gno has no dynamic dispatch by path, so a mount cannot be a
client pulling a server by name; `/srv` is not a convenience here, it is the
only available mechanism, which is a pleasing accident.

The tree is read-only, like every [`synfs`](../../../../../p/moul/x/plan9/synfs/v0)
tree: the files have no `Write`, so grafting this into a stranger's namespace
cannot be turned into a write against this realm.

## Why `/dev/session` is the interesting one

A gno.land account session is a delegated key scoped to a list of path
prefixes. That is Plan 9's "the namespace *is* the capability set", rediscovered
thirty-four years later, minus the ability to look at it as a tree. This file
prints it.

Design and analysis:
[moul/gno-contracts#136](https://github.com/moul/gno-contracts/issues/136).


---

**Not affiliated with Plan 9.** Plan 9 from Bell Labs is the work of the
Computing Science Research Center at Bell Labs; the name and the marks are
theirs, and the copyright is held by the [Plan 9 Foundation](https://p9f.org).
This realm borrows the vocabulary and none of the code: it is an independent
homage, asking what that ecosystem's spirit looks like on a chain. Full
attribution: [NOTICE](../../../../../NOTICE.md).

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---

Part of **[moul/gno-contracts](https://github.com/moul/gno-contracts)** — moul's versioned gno.land contracts. See the repository for the full catalog, build/test tooling, and usage.

**Dependency graph:**

![gno.land/r/moul/x/plan9/dev/v0 dependency graph](https://raw.githubusercontent.com/moul/gno-contracts/main/_assets/gno.land/r/moul/x/plan9/dev/v0/deps.png)

> 🧪 **Highly experimental — potentially vibe-coded.** Not audited; may break, change, or be removed at any time. Do not use with anything of value. Full disclaimer: [DISCLAIMER](https://github.com/moul/gno-contracts/blob/main/DISCLAIMER.md).

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