dotfiles/README.md
Jonny Barnes 80683b82c1
Add git sync, and stop trusting the cached default branch
BuildEmpire/Totara renamed its default branch from main to totara-20.
Nothing local noticed, because refs/remotes/origin/HEAD is written once at
clone time and remote.<name>.followRemoteHEAD defaults to `create`, which
only fills the ref in when it is missing. So `git default-branch` still
said main, as did nvim's diff-against-branch prompt.

bin/git-sync does the start-of-work sequence for a fork - fast-forward the
default branch from upstream, push it to origin - and works out which
branch that is by asking the server, not the cache. It sets the cached
HEADs from the answer, so everything reading that ref agrees afterwards.
It lives in bin/ rather than as an alias because git picks up git-<name>
on the $PATH as a subcommand, and this is more shell than a gitconfig
alias should hold. followRemoteHEAD = always is set for origin as well, so
an ordinary fetch keeps the ref current without running the script.

The nvim prompt now prefers origin, then upstream, then the remaining
remotes. It took the first remote alphabetically before, which in
be-edition means kdog - a colleague's fork - rather than anything
authoritative.

Verified against a fixture of bare repos whose default branch is
totara-20 and whose cached HEAD is stale: the branch is created tracking
origin when absent, fast-forwarded when behind, pushed to the fork,
refuses to merge when the local copy has diverged, and is a no-op on a
second run. The nvim prompt was checked in three real repos.
2026-08-27 16:05:49 +01:00

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# dotfiles
Heres my dotfiles, inspired by people like Mathias. See his dotfiles at
[`https://github.com/mathias/dotfiles`](https://github.com/mathias/dotfiles).
The idea Im currently going down is to create a symlink from `$HOME` to this
directory. There is one exception to this, the `.gitconfig` file. I dont want
actual commiter details committed into this repo, and they differ per machine
anyway — this Mac signs with my work address, the iMac with my personal one.
So identity and signing live in an untracked `$HOME/.gitconfig.local`, which the
tracked `gitconfig` pulls in with an `[include]` as its **last** directive. Last
matters: git applies config in file order, so anything after the include would
override it.
`$HOME/.gitconfig` is copied rather than symlinked, so that an ad-hoc
`git config --global` writes into `$HOME` instead of dirtying this repo. The
trade-off is that `git pull` alone does not update it — re-run `./bootstrap.sh`,
or `cp gitconfig ~/.gitconfig`, after changing the tracked copy.
## Usage
First clone the repo.
Run `./bootstrap.sh`, this will create all the necessary symlinks, then source
`.zshrc`.
> [!WARNING]
> This is a **destructive** process, so backup your dotfiles first.
As mentioned above, git identity lives in an untracked `$HOME/.gitconfig.local`.
`bootstrap.sh` seeds it from `gitconfig.local.template` if it does not already
exist, and never overwrites an existing one. Fill it in:
```
[user]
name = Jonny Barnes
email = jonny@jonnybarnes.uk
signingkey = ssh-ed25519 AAAA...
[commit]
gpgsign = true
[gpg "ssh"]
program = /Applications/1Password.app/Contents/MacOS/op-ssh-sign
```
Do not skip this. Git will not prompt you — with no identity it quietly derives
one from your username and hostname, warns once, and signs nothing.
`$HOME/.extra` is a separate untracked file for other machine-local environment
variables, sourced from `.zshrc`. Keep git out of it:
> [!IMPORTANT]
> Never put `git config --global` in `.extra`. It is re-sourced on every
> `SIGUSR1`, so with several tmux panes the concurrent writes race on
> `~/.gitconfig.lock` and spew `error: could not lock config file`. Put git
> settings in `.gitconfig.local` instead.
## Fork workflow
Work repos are forks: `origin` is mine, `upstream` is the one PRs are raised
against. `git sync``bin/git-sync`, found as a subcommand because it is on the
`$PATH` — does the start-of-work dance:
```
git sync # fast-forward the default branch from upstream, push it to origin
```
It asks the server which branch is the default rather than assuming `main`,
fast-forwards only (a diverged default branch is something to look at, not to
merge), and pushes to `origin` so the fork's copy matches. Then branch off it as
usual, push the branch to `origin`, and raise the PR against `upstream`.
The awkward part is that **git caches the default branch and does not refresh
it**. `refs/remotes/origin/HEAD` is written once, at clone time; the default
`remote.<name>.followRemoteHEAD = create` only fills it in when missing. So
BuildEmpire/Totara renaming its default from `main` to `totara-20` left every
clone still reporting `main``git default-branch` included. Two things fix
that: `followRemoteHEAD = always` in the gitconfig re-points the ref on every
fetch, and `git sync` sets it explicitly from what the server just said.
Anything wanting the base branch should read that ref, and prefer `origin` when
doing so. `git remote` sorts alphabetically, so picking the first remote in
be-edition returns `kdog` — a colleague's fork. nvim's `<leader>gm`
(diff-against-branch) tries `origin`, then `upstream`, then the rest.
## Light and dark mode
Most of this is now handled natively and needs no configuration:
- **ghostty** follows the system appearance itself via
`theme = light:tangere-light.conf,dark:tangere-dark.conf`.
- **tmux** 3.6+ learns the terminals theme over OSC 2031 and exposes it as
`#{client_theme}`.
- **bat** picks a theme per invocation from `BAT_THEME_LIGHT` / `BAT_THEME_DARK`.
- **delta** and **nvim** detect the terminal background themselves.
The tmux status bar needs help, because its colours are set explicitly. They live
in `tmux-light.conf` and `tmux-dark.conf` — the same layout, with each colour
taken from the matching tangere palette index — and `tmux` sources one of them
from three hooks:
- `client-light-theme` / `client-dark-theme` react to a change,
- `client-attached` picks the right one for a client that attaches mid-way, since
the two above only fire on a change.
Because this keys off the terminal's reported theme rather than a schedule, it
behaves identically whether the change came from Auto at sunrise/sunset or from
toggling Light/Dark by hand — nothing in the chain knows why it changed.
> [!NOTE]
> A running nvim will not follow a live change: the docs are explicit that the
> TUI sets `background` *on startup* if it can detect it. New instances are
> fine — verified, a fresh nvim in light mode reports `background=light` — but
> existing ones need `:set background=light` or a restart.
Verified in light mode: the status bar switches in the same second the hook
fires, a fresh nvim detects `light`, and delta resolves its light default
(`syntax-theme = GitHub`, against `Monokai Extended` on dark).
> [!TIP]
> When adding these hooks to an *already running* tmux server, detach and
> reattach. tmux enables the terminals theme-reporting mode when a client
> attaches, so a client that predates the hooks never gets asked to report
> changes — `#{client_theme}` still reads correctly, because that is answered by
> a direct query, but no hook fires until the client reattaches.
> [!NOTE]
> This previously used [`dark-mode-notify`](https://github.com/bouk/dark-mode-notify)
> as a `launchd` agent that ran `pkill -usr1 zsh` on every appearance change.
> That has been removed. It could never have worked: re-sourcing `.zshrc` runs
> inside each *shell*, but the status bar belongs to the tmux *server* and
> colours to a running nvim, so it could not retheme either. The one variable it
> set was read by nothing. Meanwhile it fired on every unlock, re-running
> `.zshrc` in every pane. Dont bring it back.