omh 0.4.0

Launch any coding harness, in a sandbox, with your setup already there.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61

# Rust — what a repo with a Cargo.toml needs in order to be worked on.
#
# Every provide states what it buys (`because`) and, where somebody has taken
# one, what it costs (`measured`). Costs are measured and benefits are argued;
# they are different kinds of claim and this file keeps them apart, exactly as
# the base set does.

name   = "rust"
marker = "Cargo.toml"

# Three things here are not obvious, and each was got wrong first:
#
#   RUSTUP_HOME/CARGO_HOME under /usr/local — `install` runs as root, so the
#   default `$HOME/.rustup` is `/root/.rustup`, and `/root` is mode 700. The
#   agent could not read it even if it looked there.
#
#   The *toolchain's* binaries are linked, not rustup's shims. A shim resolves
#   its toolchain through `$HOME/.rustup` at run time, so a root-installed one
#   sends the agent looking in `/home/agent/.rustup`, which does not exist —
#   `could not create home directory ... Permission denied`. The real binaries
#   under `toolchains/*/bin` need no environment at all.
#
#   `-c rustfmt -c clippy` — the minimal profile ships neither, and rustup's
#   install-on-demand only happens through the shims this deliberately avoids.
[[provide]]
name    = "toolchain"
needs   = ["cargo", "rustc", "rustfmt", "cargo-clippy"]
install = "export RUSTUP_HOME=/usr/local/rustup CARGO_HOME=/usr/local/cargo && curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal -c rustfmt -c clippy --no-modify-path && ln -sf /usr/local/rustup/toolchains/*/bin/* /usr/local/bin/ && chmod -R a+rX /usr/local/rustup /usr/local/cargo"
because = "cargo is how a rust project is built, tested and formatted; without it neither the agent nor the human can check a change"

  # Taken with a *default* profile, which is not what this recipe installs —
  # said plainly rather than converted into an estimate, because a number
  # nobody took reads exactly like one somebody did.
  [[provide.measured]]
  what  = "on disk, default profile (this recipe installs minimal plus rustfmt and clippy)"
  value = "1.5 GB"
  how   = "du -sh ~/.rustup after `rustup -y --profile default`, aarch64"
  on    = "2026-08-14"

  [[provide.measured]]
  what  = "of that, the documentation --profile minimal omits"
  value = "904 MB"
  how   = "du -sh ~/.rustup/toolchains/*/share/doc, same install"
  on    = "2026-08-14"

# rustup delivers a working `cargo` and still cannot produce a binary without a
# linker. The recipe above succeeded on an image with no `cc`, `ld` or `ar`, and
# `cargo test` failed at the last step — which is why `needs` and `install` are
# separate fields, and why this is a provide of its own rather than a line in
# the one above.
[[provide]]
name    = "linker"
needs   = ["cc", "ld", "ar"]
install = "apt-get update && apt-get install -y --no-install-recommends gcc libc6-dev && rm -rf /var/lib/apt/lists/*"
because = "rustc compiles without a linker and then cannot link, so every build fails at the last step"

  [[provide.measured]]
  what  = "on disk"
  value = "124 MB"
  how   = "sum of dpkg Installed-Size for gcc, gcc-12, libc6-dev, binutils and their deps, aarch64"
  on    = "2026-08-14"