# Oxygen user guide

This guide is organised by task. It assumes the `oxy` binary is on your

path (`cargo build --release` puts it in `target/release/`). The design

behind every command is in [spec.md](spec.md); this guide only tells you

what to type and what to expect.

Oxygen tracks *changes* rather than snapshots: a change is the set of

edits you made, it commutes with unrelated changes, and conflicts are

recorded in history instead of blocking you. Two ideas recur below:

- A **bookmark** (default `main`) names a *state*: the set of changes it

  contains. A state can have several **heads** when independent changes

  have not been related to each other; that is normal, not a problem.

- The **working copy** is itself a change that Oxygen rewrites every time

  it looks at your files. `oxy commit` turns it into a real change.

Output uses colour and glyphs on a terminal; pipe it, pass `--plain`, or set

`NO_COLOR` for plain ASCII.

## 1. Set yourself up

```

oxy identity create --name "Ada Lovelace" --email [email protected]

oxy config --user core.sign change

```

`identity create` generates a composite Ed25519 + ML-DSA-65 key pair, keeps

the secret in `~/.config/oxy/keys/`, and records you as the default author

in `~/.config/oxy/config.toml`. With `core.sign = change` every commit is

signed; without it, changes are sealed in batches when you push (also

authenticated, just later). Use `--local` to record the identity in one

repository only.

`oxy identity show` prints the key, its expiry, delegates, and whether the

secret is available. `oxy identity export` writes the public identity to a

file to hand to whoever manages a trust policy (section 8).

## 2. Start a repository

```

mkdir project && cd project

oxy init

oxy status

```

`oxy init` creates `.oxy/`. Add `.oxyignore` (gitignore syntax, per

directory, negations with `!`) for files that should never be tracked;

`/target` and `*.tmp` are typical entries. As in Git, ignore rules only

affect untracked files: a file already in history stays tracked until you

delete it. A project's `.gitignore` files are honoured too, so moving a Git

project to Oxygen does not commit its build output; `.oxyignore` comes

first, and a `!` rule there brings back what `.gitignore` leaves out.

To take over an existing Git project, see section 12.

## 3. Everyday work

```

oxy status                 # what changed since the last commit

oxy diff                   # the edits, file by file

oxy commit -m "Add retry loop"

oxy log                    # newest first; -n 10, -v for full messages

oxy log -r 'main.. & touches("src/**")'   # a revset (docs/revset_query_language.md)

oxy show 658990aa          # one change by ChangeId prefix, #hash prefix, or @

```

`oxy log` draws the history as a graph, newest first, two lines per change:

```

◉  2f8518c0 Andy McCall just now

│  (working copy)

●  1b5888b1 Andy McCall 2 minutes ago main #cc23b999 ✔ signed

│  Edit b

│ ●  d6f52eca Andy McCall 3 minutes ago main #ec6a7dc4 ✔ signed

├─╯  Edit a

○  c0593116 Andy McCall 5 minutes ago #eeac7940 ✔ signed

   Both files

```

The bright start of each ID is the shortest prefix that names it. `●` marks

a head, `◉` the working copy. Bookmarks and tags show beside their heads,

unless they have more than three. A lane follows the change each one most

directly builds on, its newest dependency. Two edits that build on the same

change take two lanes, which join above it, so independent work shows side

by side. `~` means the change builds on something further down than the

graph draws, or not shown; `-v` lists every dependency.

Commit part of what changed with `oxy commit PATH.. -m "..."` (only those

paths; the rest stays as uncommitted work) or `oxy commit -i -m "..."`, which

offers each hunk in turn like `git add -p`; a hunk that another chosen hunk

needs, such as the directory a new file lives in, comes along by itself.

`status --json` prints the same for tools, with every conflict's kind, path and

contributing ChangeIds. On a terminal, `status` lists each path with a mark: `✚ added`, `✎ modified`, `✖ removed`,

`➜ renamed`, `⚙ mode`. Renames are detected: a removed file and an added

file of the same kind whose contents are at least half alike are recorded

as a move of the same file, so identity survives a rename.

Files containing NUL bytes are stored whole ("opaque"); text files are

stored line by line and merge line by line. `.oxyattributes` overrides the

guess (section 14).

Every change has two names: a **ChangeId** (`658990aa…`) that survives

rewrites, and a content hash (`#7469d16c…`) that changes when the change is

edited. Use whichever you have; prefixes work.

## 3a. Bookmarks: branches without merges

A bookmark names a state; each workspace works on one (`main` to begin

with). Because changes commute, "merging" is the union of two bookmarks'

heads, with no merge change and any real conflict recorded as in section 6.

```

oxy bookmark create feature        # at the working copy's base

oxy bookmark switch feature        # check it out; commits now go here

oxy commit -m "Feature work"

oxy bookmark switch main

oxy merge feature                  # main now holds both; working copy follows if clean

oxy bookmark list                  # ● current, heads, ↑n/↓n against origin

oxy push -b feature                # publish a bookmark other than the current one

oxy bookmark set feature 658990aa  # move it; oxy bookmark delete feature to drop it

```

`oxy checkout feature` materialises a bookmark without switching to it, and

a bookmark name works wherever a change is expected when it has one head.

Each workspace remembers its own bookmark, so two directories can sit on

two bookmarks of one repository.

**A state is its heads, not a history.** If you are coming from Git, this

is the one thing to know. A bookmark holds its heads and what they depend

on, and a change depends only on the changes it builds on (the files it

touched), not on everything recorded before it. So on a bookmark with

several heads, a new bookmark at one change can be a much older-looking

tree. `oxy bookmark create NAME CHANGE` refuses when that would leave out

earlier work and lists what it would lack. Then pick one:

```

oxy bookmark create logo 745307b4 --upto  # everything here up to that change, as a Git branch would be

oxy bookmark create logo 745307b4 --only  # just that change and what it depends on

oxy bookmark create logo                  # the whole current state, usually what you want

```

`oxy bookmark set NAME CHANGE` asks the same when the move would lose

changes the bookmark holds that were recorded before CHANGE, and takes

`--upto` and `--only` too. After merging a proposal's target into its

bookmark to resolve conflicts, `oxy bookmark set NAME CHANGE --upto`

keeps everything the bookmark held.

`oxy bookmark switch` says when the bookmark you switch to lacks changes

that the one you left has.

**A remote's bookmarks.** A clone fetches every change, checks out the

remote's default bookmark, and names the others `origin/NAME`: use them

anywhere a bookmark is expected (`oxy log origin/develop`,

`oxy diff main origin/develop`). `oxy bookmark list --all` shows them.

`oxy bookmark switch develop` makes a local `develop` from `origin/develop`

when there is none, and `oxy pull` then keeps every local bookmark up to

date with the remote's of the same name, not only the current one. Pulling

is a union, so this never loses work.

```

oxy clone https://oxygenhub.io/owner/game --recursive   # subrepos too

oxy bookmark list --all

oxy bookmark switch develop        # from origin/develop

oxy pull                           # updates develop, main and the rest

```

### A develop / feature flow

Names with `/` work everywhere, pushing included:

```

oxy bookmark create feature/42-login          # at the working copy's base

oxy bookmark switch feature/42-login --carry  # started already? take the edits along

oxy commit -F msg.txt                         # a long message from a file

oxy push -b feature/42-login

oxy bookmark switch develop

oxy merge feature/42-login                    # the working copy follows when it was clean

oxy push                                      # develop, with the feature in it

oxy bookmark delete feature/42-login          # oxy push --delete feature/42-login on the remote

```

`bookmark switch` stops when the working copy has uncommitted edits, so

nothing is lost by accident. There are two ways past it:

- `--carry` takes the edits along. It is refused only when the target

  bookmark has other versions of the files they touch.

- `--discard` drops the edits.

`oxy describe` names what the working copy holds, for build stamps:

- a tag, when a tag holds exactly this state;

- otherwise the nearest tag with the distance from it and the change;

- or, with no tag behind it, the bookmark and the change;

- with `-dirty` added when there are uncommitted edits.

## 4. Fix up history

Oxygen keeps its own record of every operation, so all of these are safe to

try and to undo.

```

oxy describe -m "Better message"        # reword the head the working copy sits on

oxy describe 658990aa -m "..."          # reword any change; dependents are rewritten

oxy amend                               # fold the working copy into the head

oxy amend --into 658990aa               # fold it into an older change

oxy split 658990aa src/parser.rs        # split a head: those paths become a separate first change

oxy abandon 658990aa                    # drop a change; its content stays on disk

oxy squash 658990aa --into 9df9ac29     # fold a change into one it depends on

oxy rebase 658990aa --onto feature      # re-express a change against another base

oxy rebase 658990aa --onto develop --into-working-copy   # conflicted? resolve it here, then commit

oxy undo                                # undo the last operation, whatever it was

oxy op log                              # every operation, what it changed, and its command

```

### The operation log

Every command that changes the repository records an operation: the

bookmarks, tags and working copy as they were after it. `oxy op log` lists

them newest first, each with what it changed and the command that did it;

working-copy snapshots fold into one row.

```

@  13adb0d0b8bf just now

│  main: 1 → 2 heads; working copy now 91ab4d50

│  oxy commit -m "Third"

○  fa21727d70da just now

│  created bookmark test (1 head)

│  oxy bookmark create test

○  2d15930afdef … 830168a3ddcd just now

│  2 working-copy snapshots

```

Any operation can be looked at, gone back to, or undone alone:

```

oxy --at-op fa21727d log                # the log as it was after that operation; any read-only command works

oxy op restore fa21727d                 # bookmarks and working copy as they were then

oxy op revert fa21727d                  # undo just that operation, keeping everything after it

oxy undo                                # takes back the last command, a restore included

```

`op restore` and `op revert` are operations themselves, so `oxy undo` takes

them back. `op revert` puts back each bookmark the operation moved, unless

it has moved again since. Tags and the trust policy never go backwards.

`undo` brings the files back as well when nothing uncommitted would be

lost; an undone commit's edits stay on disk as uncommitted work.

Commands that move the working copy end by saying where it is:

```

* Committed 95245a21 #35bbf5097e0c  Third

  Working copy  91ab4d50

  Bookmark      main: 2 heads, newest 95245a21 Third

```

Rewriting a change that others depend on rewrites them too, keeping their

ChangeIds. Because unrelated changes already coexist, `rebase` is rarely

needed; its job is to change what a change is said to build on, for instance

to drop a dependency on something you are about to abandon. Where a dependent referred to a line that no longer exists, the

reference is re-anchored to the nearest surviving line and `oxy abandon`

prints a note about it.

## 4a. Who wrote this, and what broke it

```

oxy blame src/parser.rs          # every line: the change that introduced it, author, age

oxy blame src/parser.rs --json

```

Blame is exact: each line is an atom that remembers the change that

introduced it, so renames cost nothing and there is no heuristic.

```

oxy bisect start

oxy bisect good v1.2             # a change, bookmark or tag known to be fine

oxy bisect bad main              # and one known to be broken

oxy bisect run make test         # exit 0 good, 125 skip, anything else bad

oxy bisect reset                 # back to where you were

```

Without `run`, each step checks out a state to test and you answer with

`oxy bisect good`, `bad`, or `skip`. The candidates are the changes the bad

state has that the good one lacks, ordered so every tested state is

well-formed; the answer is the first change whose inclusion breaks things.

## 5. Move around

```

oxy checkout                    # the bookmark's heads

oxy checkout 658990aa           # the state of one change and its dependencies

oxy checkout v1.2               # a tag

oxy checkout --discard ...      # throw away uncommitted work first

```

Checking out a single older change gives you the files that change and its

dependencies touch, not a full snapshot from that date: in Oxygen a change

depends only on what it actually builds on.

## 6. Conflicts

A conflict never stops a commit, fetch, or pull. It is recorded in the

state and shown by `oxy status`, which exits with status 2 while any

conflict remains. Conflicted text files are written with markers:

```

<<<<<<< oxy conflict 1 of 2, side 1: change k7m2p9 "Add retry loop"

... lines ...

======= oxy conflict 1 of 2, side 2: change q3x8w1 "Refactor client"

... lines ...

>>>>>>> oxy conflict 1 of 2 end

```

Edit the file to what it should be (keep one side, both, or neither) and

remove the markers. Tree conflicts, such as two files wanting the same

name, appear as `<name>.oxy-conflict-<n>` candidates: keep the one you

want under the right name and delete the rest.

```

oxy resolve      # which conflicts your edits resolve, which still have markers

oxy commit -m "Resolve retry vs refactor"

```

The commit is recorded as a *resolution*, a change that depends on every

side of the conflict; anyone who fetches it gets the conflict resolved.

## 7. Work with others

Run a server (any machine with the repositories under one directory):

```

oxy serve --root /srv/oxy --bind 0.0.0.0:8890 --token SECRET \

          --tls-cert cert.pem --tls-key key.pem

```

Without `--tls-*` the server speaks plain HTTP; keep that on a loopback

address or behind a TLS terminator. `--token` makes pushes require a bearer

token; reads stay open.

On your machine:

```

echo SECRET | oxy auth login https://host:8890 --with-token --ca my-ca.pem

oxy clone https://host:8890/project

cd project

oxy push

oxy pull

```

`--ca` is only for a server with a self-signed certificate. On a hub such as

OxygenHub, `oxy auth login https://oxygenhub.io` signs in through the

browser instead: it shows a code to approve on the hub, and the hub issues a

token that lasts 90 days past its last use.

### Signing in

`oxy auth login HUB` keeps one token per hub (scheme, host and port) in

`~/.config/oxy/credentials.toml`, readable by you only, and every repository

on that hub uses it: clone, fetch, push and subrepos alike. Nothing secret is

written into a checkout. `oxy auth status` lists the hubs you are signed in

to and checks each token with its hub; `oxy auth logout HUB` forgets the token

and revokes it on the hub.

To keep tokens in the system keyring instead, name a Git credential helper:

`oxy config --user auth.helper libsecret` (Linux), `osxkeychain` (macOS) or

`manager` (Windows). The file then keeps only the account and CA.

A token is found in this order: the remote's own `remote.<name>.token`, then

`$OXY_TOKEN` (for CI), then the store, then a remote on the same hub in an

enclosing checkout (so a subrepo uses its parent's). oxy sends a token over

`https` only, or over plain `http` to this machine; it is never sent to

another host after a redirect, and a credentials file that others can read

is ignored.

- `oxy fetch` updates `origin/main` without touching your bookmark.

- `oxy pull` fetches, then makes your bookmark, and every other local

  bookmark the remote also has, the union of both sides.

  There is no merge commit; unrelated changes simply coexist, and a real

  conflict is recorded as in section 6. The working copy follows when it was

  clean.

- `oxy push` sends your changes and moves the remote bookmark. If the remote

  moved since you last fetched, the push is refused: pull and push again.

  `--force` overrides the compare-and-swap.

- `oxy remote add|remove|list` manages remotes; the clone source is `origin`.

A repository can also be cloned from a local path, which is handy for tests

and for a bare "hub" on a shared disk.

## 8. Decide who may publish: the trust policy

Without a policy a repository is *unverified*: everything is accepted and

every remote command says so. A policy names root keys and the keys allowed

to update each bookmark; servers and clients enforce it.

```

oxy policy init                    # your key becomes the only root; push publishes it

oxy policy show

oxy policy grant alice.identity    # alice.identity came from her `oxy identity export`

oxy policy grant ci.identity --pattern 'release/*'

oxy policy revoke 9458b656         # by KeyId prefix

oxy verify                         # signature status of every change in the log

```

Several people can hold root keys:

```

oxy policy root add bob.identity

oxy policy root threshold 2        # future updates need two root signatures

```

Once the threshold is above one, an update you make alone becomes a

*proposal file* (`policy-<serial>.proposal`, or `--out`). Send it to another

root holder, who runs `oxy policy sign policy-7.proposal`; whoever completes

the threshold applies it, and the next push publishes it. Everyone else

picks it up on fetch, verifying each step from the policy they already

trust.

## 9. Keys over time

```

oxy identity rotate                   # fresh key pair; old signatures stay valid

oxy identity renew --expires 365      # same keys, new expiry in days (0 = never)

oxy identity delegate add agent.identity --expires 8h       # sign changes for me today

oxy identity delegate add ci.identity --scope changes,refs  # sign and push for me

oxy identity delegate remove 3f2a…

oxy identity revoke 3f2a… --reason "agent host compromised" # a key you delegated to

```

Setting an agent up takes a home of its own, so it never holds your

secret key. In the agent's shell, inside any checkout:

```

export OXY_HOME=~/.oxy-agents/claude

oxy identity create --name "Claude Code on my laptop" --email [email protected]

#   prints the agent's KeyId; its identity file is keys/<KeyId>.identity in that home

oxy config --user author.name  "Your Name"      # the agent authors as you…

oxy config --user author.email "[email protected]"

oxy config --user author.key    <YOUR KeyId>

oxy config --user author.signer <THE AGENT's KeyId>   # …and signs as itself

oxy config --user core.sign     change

```

Then, in your own shell, in the repository: `oxy identity delegate add

~/.oxy-agents/claude/keys/<KeyId>.identity --scope changes --expires 8h`

(several files at once are one rotation). This rotates your identity:

the new key is written to your user config, and to this repository's

file too if it pinned the old one, so other checkouts follow; put the

new KeyId in each agent's `author.key`, and re-link it on your hub.

`oxy identity show` warns if a repository still pins an older key

(`oxy config --unset author.key` there). Every commit the agent makes

carries you as author and its signature: `oxy log -r 'delegated()'`

lists them, `oxy verify` names the agent, and its own `oxy push` is

refused under any policy, so you land its work.

```

oxy identity revoke                   # retire your own key

oxy identity revoke 3f2a… --reason "laptop stolen"   # any key, if you hold a root

```

Rotation, renewal, and delegation all issue a successor identity that names

the previous one. If a policy names your key, it is updated to the successor

in the same step (as a proposal when more root signatures are needed).

Changes signed before the rotation remain authorised; a revoked key

authorises nothing. `oxy verify` shows signatures by revoked keys as valid

but revoked.

## 10. Tags and workspaces

```

oxy tag create v1.2 -m "First release"   # the current heads; or name changes

oxy tag list

oxy workspace add ../project-hotfix      # a second checkout sharing the repository

oxy workspace list

oxy workspace forget ../project-hotfix

```

A tag is an immutable state, signed when you have a key, and travels with

push and fetch. Workspaces have their own working copy and bookmark

(`workspace.bookmark`) but share objects and history.

### Receipts from CI

A runner such as OxygenFlow signs a receipt for every job it runs: what ran,

in what environment, on which files, and the result. Receipts are kept with

the state they ran on.

```

oxy receipt list                         # receipts for the bookmark's state

oxy receipt show 3f2a9c                  # one in full, with its signature checked

oxy receipt export 3f2a9c build.receipt  # hand it to someone

oxy receipt verify build.receipt         # check one without keeping it

oxy receipt import build.receipt         # verify and keep it

```

## 11. Big repositories: partial, sparse, shallow

```

oxy clone URL --max-blob 1M          # files above 1 MiB are fetched on first read

oxy clone URL --sparse src --sparse docs   # materialise only these subtrees

oxy clone URL --depth 50             # only the last 50 levels of history

oxy sparse src docs tests            # change the filter later

oxy deepen 100                       # fetch more history below the boundary

```

Lazy blobs and sparse trees do not affect commits: what you do not have is

left exactly as it was. A shallow clone starts from a *checkpoint* of the

state, so status and commit work at full speed from the first minute.

## 11a. Nested repositories (submodules)

A subrepo is another repository checked out at a path and pinned to a state,

Oxygen or Git. The pin is versioned like a file, so two people pinning

different states get an ordinary conflict.

```

oxy submodule add https://host/lib.git libs/lib     # Git or Oxygen URL; records .oxymodules

oxy commit -m "Add lib"                              # the pin is committed with the parent

oxy submodule status                                 # pin vs what is on disk

oxy submodule update --init                          # after a clone: fetch nested repositories

oxy submodule remove libs/lib                        # drop the node; the directory stays

```

Committing the parent records whatever the nested repository is at, and

checking out an older parent state moves the nested repository back, unless

it has uncommitted changes, which are never overwritten. An absent nested

repository keeps its pin until you run `update --init`. A `.oxymodules`

section written by hand has no pin until `oxy submodule add` clones it;

`status` and `update` name such entries, and `update` exits non-zero. Git

submodules survive `oxy git import` as Git pins and go back out as gitlinks

on export.

## 12. Git interoperability

```

oxy git import ../project.git ./project-oxy --branch main   # convert a Git history

oxy git fetch https://github.com/you/project.git            # bring new Git commits in

oxy git push  https://github.com/you/project.git            # publish your changes to Git

oxy git export ../mirror.git                                # a plain Git mirror of the bookmark

```

Import turns each commit into one change (merge commits become

resolutions), keeps authors and hashes as `Git-Author`/`Git-Commit`

trailers, detects renames, and skips submodules. `git fetch`/`git push` keep

a bare mirror under `.oxy/git/`; a push is refused until the remote's tip

has been fetched, so it always fast-forwards. Exported commits carry

`Change-Id` and `Oxy-Hash` trailers.

## 13. Automate: hooks

Executables in `.oxy/hooks/<event>` (never cloned) receive one JSON object

on stdin. `pre-commit`, `pre-push` and other `pre-*` hooks veto by exiting

non-zero, and their stderr becomes the error message. Events:

`pre-commit`, `post-commit`, `pre-push`, `post-fetch`, `post-checkout`, and

`semantic-deps`, which runs at commit when `hooks.semantic-deps = true` and

answers `{"deps": ["<hash>", …]}` to make the change depend on more than it

textually references.

## 14. Per-path attributes, ignores, locks

`.oxyattributes` uses gitattributes syntax:

```

*.png     binary

*.txt     text eol=lf

*.psd     lockable nocompress

```

`binary`/`text` override content sniffing, `eol=lf|crlf` normalises line

endings in the store and on checkout, `nocompress` stores chunks raw, and

`lockable` files are checked out read-only until you take the local lock:

```

oxy lock assets/logo.psd

oxy unlock assets/logo.psd

```

Locks are advisory and local; server-side locks are planned.

## 15. Configuration

Two files, both `key = "value"` lines: `~/.config/oxy/config.toml`

(`oxy config --user KEY VALUE`) and `.oxy/config` (`oxy config KEY VALUE`).

The repository file wins. `OXY_HOME` relocates the user directory. `OXY_TIMINGS=1` prints how long each phase of a snapshot takes (loading the base state, rendering it, reading the working copy, building the change) to standard error, for finding out where a slow command spends its time. Built with `cargo build --release --features alloc-stats`, oxy also reports each phase's live and peak memory and what it allocated, and a summary at the end.

| Key | Meaning |

|---|---|

| `author.name`, `author.email`, `author.key` | who you are; `key` is set by `identity create` |

| `author.signer` | the key that signs instead of `author.key`: an agent's own key, which your identity lists as a delegate (also `$OXY_SIGNER`) |

| `core.sign` | `change` to sign every commit; otherwise seals at push |

| `core.op-retention` | days for which old operations keep their states alive (90) |

| `core.gc-grace` | days an unreachable object survives (14) |

| `core.checkpoint-interval` | changes between automatic checkpoints (256) |

| `filter.max-blob`, `filter.paths` | lazy blobs and sparse subtrees (section 11) |

| `hooks.semantic-deps` | run the semantic-deps hook at commit |

| `workspace.bookmark` | this workspace's bookmark (`main`) |

| `remote.<name>.url`, `.token`, `.ca` | remotes; token and CA fall back to `OXY_TOKEN` and `OXY_CA`, then `oxy auth login`'s store |

| `auth.helper` (user file) | a Git credential helper to keep `oxy auth` tokens in, such as `libsecret` |

## 16. Shell prompt

`oxy prompt` prints `main 658990aa*+2` (bookmark, working copy, `*` dirty,

`!` conflicted, ahead/behind origin) in a few milliseconds and records

nothing. See [prompt.md](prompt.md) for bash, oh-my-bash, zsh, and fish

snippets and the `--format` placeholders.

## 17. Housekeeping

```

oxy gc              # prune unreachable objects past the grace period, repack into one pack

oxy gc --now        # ignore the grace period (only when nothing else is writing)

oxy fsck            # check every object, the op log, references, signatures, checkpoints

oxy doctor          # check identity, config and remotes, with what to do about each problem

oxy checkpoint      # serialise the bookmark's state so large histories load instantly

```

Both run automatically: packing when loose objects pile up, checkpoints

every `core.checkpoint-interval` changes.

## 17a. Scripting and editors

Every reporting command takes `--json` (`status`, `log --path`, `show`,

`diff`, `hunks`, `blame`, `resolve`, `op log`, `bookmark list`, `remote list`,

`fetch`, `pull`, `push`, `submodule status`, `bisect status`, `verify`,

`policy show`, `root`, `version`). `oxy cat PATH -r CHANGE` prints a file as

it was, `oxy discard PATH..` restores files to the base, and `oxy hunks`

numbers the working copy's hunks for `commit --hunks` and `discard --hunks`.

## 18. If something looks wrong

- **"the remote has change … which you do not; pull first"**: someone

  pushed since your last fetch. `oxy pull`, then push.

- **"policy needs N root signature(s)"** on fetch: the server's policy was

  updated in a way your copy cannot verify. Ask a root holder whether the

  chain of updates was published; a fresh clone trusts the current policy.

- **`oxy status` exits 2**: conflicts remain; see section 6.

- **Many heads on `main`**: independent changes that do not reference one

  another. Nothing to fix; the state is their union.

- **Undo anything**: `oxy undo` reverts the last operation, including

  pulls, checkouts, and rewrites.

## Shell completions and man pages

```sh

oxy completions bash > ~/.local/share/bash-completion/completions/oxy   # bash

oxy completions zsh > "${fpath[1]}/_oxy"                                 # zsh

oxy completions fish > ~/.config/fish/completions/oxy.fish               # fish

oxy man --dir ~/.local/share/man/man1                                    # then: man oxy-commit

```

The oh-my-bash plugin in `contrib/oh-my-bash` loads the bash completions itself.