dev-loop

Building & testing nub

nub is a Rust workspace — three crates (nub-cli, nub-core, nub-native) plus the vendored aube PM engine (vendor/aube, plain in-tree files since Pattern B, its own Cargo workspace, linked in-process as a library). This skill is the fast, measured way to build and test it in a worktree, plus a crate map so you know where things live.

The one rule that makes iteration fast: build with the --profile fast profile (NEVER release), through scripts/rust-build.sh (scripts/rust-build.sh build -p nub-cli --profile fast). The wrapper points CARGO_TARGET_DIR at the ONE shared dir ~/.cache/nub/shared-target for the fast path — cold ≈ 3 min, every rebuild after ≈ 5s, because a second worktree reuses all the crates.io dependency artifacts (the bulk of a build) and recompiles only the ~10 workspace crates. Don't clean the shared dir between iterations — that throws away cargo's incremental cache. Why the wrapper and not a raw export CARGO_TARGET_DIR: the shared dir is safe only while every worktree agrees on the depended-on crates; two worktrees that diverge the same one (classically vendor/aube) clobber each other's rlib and fail with a phantom E0063-class error on correct source. rust-build.sh shares by default and auto-isolates to a private target dir exactly when this worktree diverges such a crate — you get the fast path in the common case and correctness in the rare one, with no manual decision. See the rust-build skill. (Tradeoff of sharing: cargo build-locks the target dir, so concurrent builds in two sharing worktrees serialize — a latency cost, never a correctness one.)

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Step 1 — Set up a worktree to iterate in

Substantive work lands via a PR from an isolated worktree. Create one with the worktree skill (nub scripts/new-worktree.ts <slug> — it bakes in the proven git worktree add … origin/main recipe). Then build through the wrapper, from the worktree root:

cd ~/.cache/nub/worktrees/<slug>
scripts/rust-build.sh build -p nub-cli --profile fast          # shared cache; auto-isolates on divergence

The wrapper shares ~/.cache/nub/shared-target so a fresh worktree reuses the crates.io dependency artifacts another worktree already compiled — it recompiles only the ~10 workspace crates instead of all ~400, and one shared dir replaces ~30 multi-GB private ones. It flips to a private target dir automatically when this worktree diverges a depended-on crate (see the rust-build skill for why). Two sharing worktrees serialize on cargo's build lock; if you need them to build at once, an isolated worktree (one that has diverged a lib crate) already runs in parallel, or set a private CARGO_TARGET_DIR by hand.

Step 2 — Build the dev binary (the fast profile)

# The dev CLI binary -> target/fast/nub. This is the iteration build.
cargo build -p nub-cli --profile fast

# Full dev binary + N-API addon, symlinked on PATH as nub-dev / nubx-dev:
make install-dev        # runs addon-fast, then `cargo build --profile fast`, then symlinks target/fast/nub

# Just the native addon (oxc transpiler), fast profile:
make addon-fast         # -> runtime/addons/nub-native.node
# Release-profile addon (only when you specifically need release behavior):
make addon

There is no nub build command — the dev build is cargo build -p nub-cli --profile fast (or make install-dev for the full binary+addon on PATH).

Build politeness on this shared dev host (HIGH PRIORITY — the maintainer works on this machine). A full cargo build can saturate all cores and make the maintainer's machine non-responsive. Two throttles keep it polite:

• Job cap (already set, machine-wide): ~/.cargo/config.toml pins [build] jobs = 6 (of 8 perf cores), so no build grabs every core. CI is unaffected (it runs on GitHub runners, not this config). Leave it in place.
• Background QoS / nice — wrap every agent build: launch builds as taskpolicy -b cargo build -p nub-cli --profile fast (macOS background QoS → schedules on E-cores + yields to interactive) or nice -n 10 cargo build …. This lets a build run without making the machine sluggish. If a build is already hammering the host, renice 20 -p <pid> + taskpolicy -b -p <pid> the running cargo/rustc tree for immediate relief.

Why fast, never release, for iteration (measured 2026-06-20, macOS arm64):

The fast profile (defined in Cargo.toml) inherits dev (debug-assertions + overflow checks stay on), drops LTO, uses codegen-units=256, line-tables-only debuginfo, and incremental=true. It is the iteration profile; release is a ship profile and must not be used to iterate.

A shared cargo target DIR (the default here) is NOT sccache — don't conflate them. sccache (a compiler-WRAPPER cache) was measured against this workspace and gives a 0% Rust cache-hit rate across separate target dirs (rustc embeds per-target-dir artifact paths in sccache's cache keys; --remap-path-prefix + CARGO_INCREMENTAL=0 does not fix it) — so sccache is NOT used. A shared cargo target dir sidesteps that entirely: with one target dir there's a single artifact path, so cargo's own incremental reuses the dependency rlibs directly across worktrees. That is why the shared dir — not a per-worktree one — is the fast path. (Seeding a private worktree target dir from a warm sibling via APFS clone is still useless — cargo invalidates the cloned fingerprints and rebuilds; the shared dir avoids the copy in the first place. There is no copy-on-write shortcut.) The catch is that a single artifact path is safe only while every sharing worktree agrees on the depended-on crates; scripts/rust-build.sh is what keeps that invariant (auto-isolating a diverged worktree) so the shared dir stays both fast and correct — see the rust-build skill.

Step 3 — Run tests

# A specific integration-test file (file stem under crates/nub-cli/tests/):
cargo test -p nub-cli --test pm_verbs
cargo test -p nub-cli --test install_engine

# A single test by name substring (across the crate):
cargo test -p nub-cli <substring>
# Pin exactly one test:
cargo test -p nub-cli -- --exact <full::module::path::to::test>

# A core/native crate's tests:
cargo test -p nub-core
# nub-native is its OWN workspace (excluded from the root one), so `-p nub-native`
# from the repo root fails — run it from inside the crate. (The cdylib sets
# `test = false`, so this just compiles the addon; its unit-testable logic lives
# in the napi-free nub-cache-key crate, covered by `cargo test -p nub-cache-key`.)
(cd crates/nub-native && cargo test)

# Everything (slow):
cargo test          # or `make test`

The nub-cli integration suite lives in crates/nub-cli/tests/*.rs — e.g. pm_verbs, install_engine, info_engine, cli_grammar_parity, pm_identity, pm_two_mode, resolution_compat, node_compat, version_tiers, workspace_run, the pm_shim* / *_config files. Use the file stem as --test <stem>.

Step 4 — Before pushing: the exact CI cheap gates

Match .github/workflows/ci.yml exactly — a scoped -p without --all-targets misses test-code lints:

cargo clippy --all-targets --all-features -- -D warnings
cargo fmt --check
cargo test -p <crate>        # scoped to what you changed

Then run the full pre-push local verification loop in AGENTS.md (incremental build → exact CI gates → e2e tmp-fixture run → Docker for global-cache/config behavior → promote durable checks into the suite). For the e2e probe loop specifically, use the ad-hoc-test skill. Get it green locally and push ONCE — fix-after-fix pushes saturate the shared CI runner pool.

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Crate map — where things live

crates/nub-cli — the CLI (clap dispatch + PM verb routing).

• src/cli.rs — the clap command grammar + dispatch (the pnpm-compatible PM surface, run/watch/nubx/upgrade/node, the top-level file runner).
• src/main.rs — entry point.
• src/pm_engine/ — routes PM verbs into the vendored aube engine in-process. mod.rs (ENGINE_VERBS), present.rs (rebrands engine output: ERR_AUBE_*→ERR_NUB_*, aube→nub), config_scope.rs (mirror-active-PM / brand-boundary config policy), identity.rs (PM-identity inference), install_family.rs, info_family.rs, publish_family.rs, store_config_family.rs, use_*.rs, and bun_config.rs / yarn_* / unsupported_config.rs for incumbent-PM compat.
• src/agent/ — agent surface.
• tests/*.rs — integration tests.

crates/nub-core — runtime/orchestration.

• src/node/ — Node integration: discovery.rs (find the user's Node on PATH), version.rs (version management), flags.rs (V8 / Node flag injection), feature_matrix.rs (tier + Node-version gating — the source of truth for version-gated feature claims), spawn.rs (process spawn), mod.rs.
• src/pm/, src/workspace/, src/version_management/.
• src/pnp.rs — Yarn PnP support.

crates/nub-native — the N-API addon (a cdylib loaded into the user's Node process). The oxc-based transpiler + resolver: transform.rs (TS/JSX transform), resolve.rs (module resolution), tsconfig.rs, cache.rs (transpile cache), detect.rs.

vendor/aube — the vendored aube package-manager engine (plain in-tree files since Pattern B, vendored from nubjs/aube). Its own Cargo workspace; nub takes path deps into vendor/aube/crates/* and calls aube::commands::<verb>::run(...) in-process. NEVER a subprocess. From a build standpoint it's just part of the workspace — cargo build compiles it as a dependency. Changes to it are normal nub edits/PRs touching vendor/aube/* (no pin, no submodule). For pulling FROM / pushing TO upstream jdx/aube, see the aube-sync skill.

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Quick reference

# fresh worktree (see the `worktree` skill: nub scripts/new-worktree.ts <slug>)
cd ~/.cache/nub/worktrees/<slug>
# build/test through the wrapper — shared cache, auto-isolates on depended-on-crate divergence (`rust-build` skill)
scripts/rust-build.sh build -p nub-cli --profile fast
scripts/rust-build.sh test  -p nub-cli --test <file_stem>

# build (fast profile)
cargo build -p nub-cli --profile fast          # -> target/fast/nub  (~3 min cold, ~5s incremental)
make install-dev                                # full binary + addon on PATH as nub-dev/nubx-dev
make addon-fast                                 # native addon only

# test
cargo test -p nub-cli --test <file_stem>        # one file
cargo test -p nub-cli <substring>               # one test by name

# CI cheap gates
cargo clippy --all-targets --all-features -- -D warnings
cargo fmt --check