diff --git a/pkgs/bun/bun.pkg.jsonc b/pkgs/bun/bun.pkg.jsonc
new file mode 100644
index 00000000000..dc0908a319f
--- /dev/null
+++ b/pkgs/bun/bun.pkg.jsonc
@@ -0,0 +1,30 @@
+// Package definition for Bun, installed from its GitHub releases.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "bun",
+  "description": "JavaScript runtime, bundler, test runner and package manager",
+  "homepage": "https://bun.sh",
+  "license": "MIT",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+  "arch_map": { "x86_64": "x64", "aarch64": "aarch64" },
+
+  "versions": { "type": "github_releases", "repo": "oven-sh/bun", "strip_prefix": "bun-v" },
+
+  "install": {
+    "type": "archive",
+    "url": "https://github.com/oven-sh/bun/releases/download/bun-v{{.Version}}/bun-{{.OS}}-{{.Arch}}.zip",
+    "checksum": {
+      "type": "sha256_url",
+      "url": "https://github.com/oven-sh/bun/releases/download/bun-v{{.Version}}/SHASUMS256.txt"
+    },
+    "strip_components": 1
+  },
+
+  // bunx is a link to bun, as Bun's own installer creates it.
+  "hooks": { "post_install": ["ln -sf bun bunx"] },
+
+  "bin": ["."],
+  "binaries": ["bun", "bunx"]
+}
diff --git a/pkgs/deno/deno.pkg.jsonc b/pkgs/deno/deno.pkg.jsonc
new file mode 100644
index 00000000000..6147c6b2974
--- /dev/null
+++ b/pkgs/deno/deno.pkg.jsonc
@@ -0,0 +1,34 @@
+// Package definition for Deno, installed from its GitHub releases.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "deno",
+  "description": "JavaScript, TypeScript and WebAssembly runtime",
+  "homepage": "https://deno.com",
+  "license": "MIT",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+  // Rust target triples.
+  "os_map": { "darwin": "apple-darwin", "linux": "unknown-linux-gnu" },
+  "arch_map": { "x86_64": "x86_64", "aarch64": "aarch64" },
+
+  "versions": { "type": "github_releases", "repo": "denoland/deno" },
+
+  "install": {
+    "type": "archive",
+    "url": "https://github.com/denoland/deno/releases/download/v{{.Version}}/deno-{{.Arch}}-{{.OS}}.zip",
+    "checksum": { "type": "sha256_url", "url": "{{.URL}}.sha256sum" },
+    "version_overrides": [
+      {
+        // Releases before 2.0.1 published no checksums and their GitHub
+        // assets have no digest; the first install records one.
+        "versions": "<2.0.1",
+        "checksum": { "type": "none" }
+      }
+    ]
+  },
+
+  // The zip holds just the deno executable.
+  "bin": ["."],
+  "binaries": ["deno"]
+}
diff --git a/pkgs/go/go.pkg.jsonc b/pkgs/go/go.pkg.jsonc
index e607b4f6606..103bfbe1492 100644
--- a/pkgs/go/go.pkg.jsonc
+++ b/pkgs/go/go.pkg.jsonc
@@ -33,8 +33,13 @@
   },
 
   "bin": ["bin"],
-  "binaries": ["go", "gofmt"]
+  "binaries": ["go", "gofmt"],
 
-  // GOROOT is intentionally not set: the go binary locates its own root and
-  // upstream discourages setting it.
+  // Run the version in devbox.json even when go.mod asks for a newer
+  // toolchain, instead of downloading that one (the same default as the
+  // nixpkgs go). GOROOT is intentionally not set: the go binary locates its
+  // own root and upstream discourages setting it.
+  "env": {
+    "GOTOOLCHAIN": "local"
+  }
 }
diff --git a/pkgs/gradle/gradle.pkg.jsonc b/pkgs/gradle/gradle.pkg.jsonc
new file mode 100644
index 00000000000..33fd2da336b
--- /dev/null
+++ b/pkgs/gradle/gradle.pkg.jsonc
@@ -0,0 +1,33 @@
+// Package definition for Gradle, installed from services.gradle.org. Gradle
+// runs on the JVM, so the project also needs java.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "gradle",
+  "description": "Build automation tool for the JVM",
+  "homepage": "https://gradle.org",
+  "license": "Apache-2.0",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+
+  // One JSON document lists every version with its download checksum.
+  "versions": {
+    "type": "http_json",
+    "url": "https://services.gradle.org/versions/all",
+    "select": ".[] | select(.snapshot or .nightly or .releaseNightly or .broken or .rcFor != \"\" or .milestoneFor != \"\" | not) | .version"
+  },
+
+  "install": {
+    "type": "archive",
+    "url": "https://services.gradle.org/distributions/gradle-{{.Version}}-bin.zip",
+    "checksum": {
+      "type": "http_json",
+      "url": "https://services.gradle.org/versions/all",
+      "select": ".[] | select(.version == \"{{.Version}}\") | .checksum"
+    },
+    "strip_components": 1
+  },
+
+  "bin": ["bin"],
+  "binaries": ["gradle"]
+}
diff --git a/pkgs/helm/helm.pkg.jsonc b/pkgs/helm/helm.pkg.jsonc
new file mode 100644
index 00000000000..cff02698221
--- /dev/null
+++ b/pkgs/helm/helm.pkg.jsonc
@@ -0,0 +1,24 @@
+// Package definition for Helm, installed from get.helm.sh.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "helm",
+  "description": "The package manager for Kubernetes",
+  "homepage": "https://helm.sh",
+  "license": "Apache-2.0",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+
+  "versions": { "type": "github_releases", "repo": "helm/helm" },
+
+  "install": {
+    "type": "archive",
+    "url": "https://get.helm.sh/helm-v{{.Version}}-{{.OS}}-{{.Arch}}.tar.gz",
+    "checksum": { "type": "sha256_url", "url": "{{.URL}}.sha256sum" },
+    "strip_components": 1
+  },
+
+  // The tarball holds <os>-<arch>/helm.
+  "bin": ["."],
+  "binaries": ["helm"]
+}
diff --git a/pkgs/java/java.pkg.jsonc b/pkgs/java/java.pkg.jsonc
new file mode 100644
index 00000000000..2a07d1f22c1
--- /dev/null
+++ b/pkgs/java/java.pkg.jsonc
@@ -0,0 +1,49 @@
+// Package definition for Java, installed as the Eclipse Temurin JDK from
+// Adoptium. Versions are OpenJDK version strings such as "21.0.5+11", so
+// `java@21` picks the newest Java 21 build.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "java",
+  "description": "Eclipse Temurin, the Adoptium build of the OpenJDK Java Development Kit",
+  "homepage": "https://adoptium.net",
+  "license": "GPL-2.0-with-classpath-exception",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+  "os_map": { "darwin": "mac", "linux": "linux" },
+  "arch_map": { "x86_64": "x64", "aarch64": "aarch64" },
+
+  // The API pages its results 50 at a time, newest first. Long-term
+  // support builds carry a ".0.LTS" suffix, which is dropped.
+  "versions": {
+    "type": "http_json",
+    "url": "https://api.adoptium.net/v3/info/release_versions?release_type=ga&vendor=eclipse&image_type=jdk&sort_order=DESC&page_size=50&page={{.Page}}",
+    "select": ".versions[].semver | rtrimstr(\".0.LTS\") | rtrimstr(\".LTS\")"
+  },
+
+  // Download names can't be derived from the version (respins are renamed,
+  // Java 8 uses "8u432b06"), so the artifact and its checksum come from the
+  // API's list of releases for the version's feature release. Java 8 has no
+  // build for Apple silicon; the API returns 404 and that platform is
+  // skipped.
+  "install": {
+    "type": "archive",
+    "lookup": {
+      "url": "https://api.adoptium.net/v3/assets/feature_releases/{{ index (splitList \".\" .Version) 0 }}/ga?os={{.OS}}&architecture={{.Arch}}&image_type=jdk&jvm_impl=hotspot&heap_size=normal&vendor=eclipse&page_size=50&sort_order=DESC",
+      "select": ".[] | select((.version_data.semver | rtrimstr(\".0.LTS\") | rtrimstr(\".LTS\")) == \"{{.Version}}\") | .binaries[0].package | {url: .link, checksum: .checksum}"
+    },
+    "strip_components": 1,
+    // macOS builds are bundles; the JDK is in <root>/Contents/Home.
+    "overrides": {
+      "aarch64-darwin": { "strip_components": 3 },
+      "x86_64-darwin": { "strip_components": 3 }
+    }
+  },
+
+  "bin": ["bin"],
+  "binaries": ["java", "javac", "jar"],
+
+  "env": {
+    "JAVA_HOME": "{{ .InstallDir }}"
+  }
+}
diff --git a/pkgs/kubectl/kubectl.pkg.jsonc b/pkgs/kubectl/kubectl.pkg.jsonc
new file mode 100644
index 00000000000..239efb132c1
--- /dev/null
+++ b/pkgs/kubectl/kubectl.pkg.jsonc
@@ -0,0 +1,24 @@
+// Package definition for kubectl, installed from the Kubernetes release
+// downloads at dl.k8s.io.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "kubectl",
+  "description": "Kubernetes command-line tool",
+  "homepage": "https://kubernetes.io/docs/reference/kubectl/",
+  "license": "Apache-2.0",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+
+  // Kubernetes releases are GitHub releases; alphas, betas and release
+  // candidates are marked as pre-releases.
+  "versions": { "type": "github_releases", "repo": "kubernetes/kubernetes" },
+
+  "install": {
+    "type": "binary",
+    "url": "https://dl.k8s.io/release/v{{.Version}}/bin/{{.OS}}/{{.Arch}}/kubectl",
+    "checksum": { "type": "sha256_url", "url": "{{.URL}}.sha256" }
+  },
+
+  "binaries": ["kubectl"]
+}
diff --git a/pkgs/maven/maven.pkg.jsonc b/pkgs/maven/maven.pkg.jsonc
new file mode 100644
index 00000000000..a23eccab279
--- /dev/null
+++ b/pkgs/maven/maven.pkg.jsonc
@@ -0,0 +1,34 @@
+// Package definition for Apache Maven, installed from Maven Central. Maven
+// runs on the JVM, so the project also needs java.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "maven",
+  "description": "Build automation and dependency management for Java",
+  "homepage": "https://maven.apache.org",
+  "license": "Apache-2.0",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+
+  "versions": {
+    "type": "http_json",
+    "url": "https://search.maven.org/solrsearch/select?q=g:org.apache.maven+AND+a:apache-maven&core=gav&rows=500&wt=json",
+    "select": ".response.docs[].v"
+  },
+
+  // Downloads come from Maven Central's CDN. Central only has digests for
+  // some releases, so the sha512 comes from the Apache release archive,
+  // which publishes one for every release since 3.5.
+  "install": {
+    "type": "archive",
+    "url": "https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/{{.Version}}/apache-maven-{{.Version}}-bin.tar.gz",
+    "checksum": {
+      "type": "sha512_url",
+      "url": "https://archive.apache.org/dist/maven/maven-{{ index (splitList \".\" .Version) 0 }}/{{.Version}}/binaries/apache-maven-{{.Version}}-bin.tar.gz.sha512"
+    },
+    "strip_components": 1
+  },
+
+  "bin": ["bin"],
+  "binaries": ["mvn"]
+}
diff --git a/pkgs/nodejs/nodejs.pkg.jsonc b/pkgs/nodejs/nodejs.pkg.jsonc
new file mode 100644
index 00000000000..901ec4bdad7
--- /dev/null
+++ b/pkgs/nodejs/nodejs.pkg.jsonc
@@ -0,0 +1,43 @@
+// Package definition for Node.js, installed from the official builds on
+// nodejs.org. npm ships with every release; add pnpm or yarn as their own
+// packages.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "nodejs",
+  "description": "JavaScript runtime built on Chrome's V8 engine, with npm",
+  "homepage": "https://nodejs.org",
+  "license": "MIT",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+  "arch_map": { "x86_64": "x64", "aarch64": "arm64" },
+
+  // index.json lists every release, newest first, as "v22.11.0".
+  "versions": {
+    "type": "http_json",
+    "url": "https://nodejs.org/dist/index.json",
+    "select": ".[].version | ltrimstr(\"v\")"
+  },
+
+  // Releases that predate a platform (no darwin-arm64 before 16) have no
+  // entry in SHASUMS256.txt and are skipped for that platform.
+  "install": {
+    "type": "archive",
+    "url": "https://nodejs.org/dist/v{{.Version}}/node-v{{.Version}}-{{.OS}}-{{.Arch}}.tar.gz",
+    "checksum": {
+      "type": "sha256_url",
+      "url": "https://nodejs.org/dist/v{{.Version}}/SHASUMS256.txt"
+    },
+    "strip_components": 1
+  },
+
+  "bin": ["bin"],
+  "binaries": ["node", "npm", "npx"],
+
+  // `npm install --global` writes into the project instead of the shared
+  // install, which every project using this version sees.
+  "env": {
+    "NPM_CONFIG_PREFIX": "{{ .Virtenv }}/npm-global",
+    "PATH": "{{ .Virtenv }}/npm-global/bin:$PATH"
+  }
+}
diff --git a/pkgs/pnpm/pnpm.pkg.jsonc b/pkgs/pnpm/pnpm.pkg.jsonc
new file mode 100644
index 00000000000..99e981b3843
--- /dev/null
+++ b/pkgs/pnpm/pnpm.pkg.jsonc
@@ -0,0 +1,43 @@
+// Package definition for pnpm, installed as the standalone executable that
+// bundles its own Node.js, so it works with or without nodejs installed.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "pnpm",
+  "description": "Fast, disk space efficient package manager",
+  "homepage": "https://pnpm.io",
+  "license": "MIT",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+  "arch_map": { "x86_64": "x64", "aarch64": "arm64" },
+
+  "versions": { "type": "github_releases", "repo": "pnpm/pnpm" },
+
+  // Since v11 every GitHub release has a tarball per platform holding the
+  // pnpm executable and its dist/ directory. GitHub records a digest for
+  // each asset.
+  "install": {
+    "type": "archive",
+    "url": "https://github.com/pnpm/pnpm/releases/download/v{{.Version}}/pnpm-{{.OS}}-{{.Arch}}.tar.gz",
+    "checksum": { "type": "github_release", "repo": "pnpm/pnpm" },
+    "version_overrides": [
+      {
+        // Before v11 the executable was published to npm as
+        // @pnpm/<macos|linux>-<arch>, and npm has a sha512 for every
+        // version. (The GitHub assets of that era have no digest.)
+        "versions": "<11",
+        "url": "https://registry.npmjs.org/@pnpm/{{ .OS | replace \"darwin\" \"macos\" }}-{{.Arch}}/-/{{ .OS | replace \"darwin\" \"macos\" }}-{{.Arch}}-{{.Version}}.tgz",
+        "checksum": {
+          "type": "http_json",
+          "url": "https://registry.npmjs.org/@pnpm/{{ .OS | replace \"darwin\" \"macos\" }}-{{.Arch}}/{{.Version}}",
+          "select": ".dist.integrity"
+        },
+        "strip_components": 1
+      }
+    ]
+  },
+
+  // Both layouts put the executable at the root of the install.
+  "bin": ["."],
+  "binaries": ["pnpm"]
+}
diff --git a/pkgs/python/python.pkg.jsonc b/pkgs/python/python.pkg.jsonc
new file mode 100644
index 00000000000..233b3655bb3
--- /dev/null
+++ b/pkgs/python/python.pkg.jsonc
@@ -0,0 +1,50 @@
+// Package definition for CPython, installed from python-build-standalone,
+// the relocatable builds that uv and mise install. The index of builds
+// (URL and sha256 per version and platform) is the one uv maintains.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "python",
+  "description": "CPython. Devbox creates a virtual environment in $VENV_DIR (default .venv) and activates it, so pip installs stay out of the shared install. Switching versions recreates a virtual environment that Devbox created.",
+  "homepage": "https://www.python.org",
+  "license": "PSF-2.0",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+  "arch_map": { "x86_64": "x86_64", "aarch64": "aarch64" },
+
+  // Versions are "3.13.1", or "3.14.0a1" for pre-releases.
+  "versions": {
+    "type": "http_json",
+    "url": "https://raw.githubusercontent.com/astral-sh/uv/main/crates/uv-python-managed/download-metadata.json",
+    "select": ".[] | select(.name == \"cpython\" and .variant == null) | \"\\(.major).\\(.minor).\\(.patch)\\(.prerelease)\""
+  },
+
+  // The default build for a platform: no free-threading or debug variant,
+  // the baseline CPU level, glibc on Linux.
+  "install": {
+    "type": "archive",
+    "lookup": {
+      "url": "https://raw.githubusercontent.com/astral-sh/uv/main/crates/uv-python-managed/download-metadata.json",
+      "select": ".[] | select(.name == \"cpython\" and .variant == null and .arch.variant == null and .os == \"{{.OS}}\" and .arch.family == \"{{.Arch}}\" and (.libc == \"gnu\" or .libc == \"none\") and \"\\(.major).\\(.minor).\\(.patch)\\(.prerelease)\" == \"{{.Version}}\") | {url, checksum: .sha256}"
+    },
+    "strip_components": 1
+  },
+
+  "bin": ["bin"],
+  "binaries": ["python3", "pip3"],
+
+  "env": {
+    "VENV_DIR": "{{ .DevboxProjectDir }}/.venv"
+  },
+  "shell": {
+    "init_hook": [
+      // Create the virtual environment, or recreate it when it was made
+      // by another version installed by Devbox. Leave any other one alone.
+      // Hooks run with `set -e`, hence `|| true` when there is no venv yet.
+      "_devbox_venv_home=\"$(sed -n 's/^home = //p' \"$VENV_DIR/pyvenv.cfg\" 2>/dev/null || true)\"",
+      "case \"$_devbox_venv_home\" in \"{{ .InstallDir }}/bin\") ;; \"{{ .CacheDir }}/python/\"*) \"{{ .InstallDir }}/bin/python3\" -m venv --clear \"$VENV_DIR\" ;; *) [ -e \"$VENV_DIR\" ] || \"{{ .InstallDir }}/bin/python3\" -m venv \"$VENV_DIR\" ;; esac",
+      "if [ \"$(sed -n 's/^home = //p' \"$VENV_DIR/pyvenv.cfg\" 2>/dev/null)\" = \"{{ .InstallDir }}/bin\" ]; then . \"$VENV_DIR/bin/activate\"; else echo \"devbox: not activating $VENV_DIR because it was not created from python {{ .Version }}; remove it to have Devbox recreate it\" >&2; fi",
+      "unset _devbox_venv_home"
+    ]
+  }
+}
diff --git a/pkgs/rust/rust.pkg.jsonc b/pkgs/rust/rust.pkg.jsonc
new file mode 100644
index 00000000000..f20259cd491
--- /dev/null
+++ b/pkgs/rust/rust.pkg.jsonc
@@ -0,0 +1,51 @@
+// Package definition for Rust. Rust's own installer is rustup, which also
+// provides `rustup target add` and `rustup component add`, so this
+// definition installs rustup-init (verified against static.rust-lang.org)
+// and has it install the requested toolchain. rustup verifies the
+// toolchain against the channel manifest.
+//
+// Toolchains live in one shared RUSTUP_HOME in the Devbox cache, and
+// RUSTUP_TOOLCHAIN selects the version, so switching versions in
+// devbox.json switches the toolchain. RUSTUP_TOOLCHAIN takes precedence
+// over a rust-toolchain.toml file.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "rust",
+  "description": "The Rust toolchain (rustc, cargo, rustfmt, clippy) managed by rustup",
+  "homepage": "https://www.rust-lang.org",
+  "license": "MIT OR Apache-2.0",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+  // Rust target triples.
+  "os_map": { "darwin": "apple-darwin", "linux": "unknown-linux-gnu" },
+  "arch_map": { "x86_64": "x86_64", "aarch64": "aarch64" },
+
+  // Every stable release is a GitHub release tagged "1.82.0".
+  "versions": { "type": "github_releases", "repo": "rust-lang/rust", "strip_prefix": "" },
+
+  // The rustup version is pinned so that installs are reproducible; it
+  // does not limit which toolchains can be installed.
+  "install": {
+    "type": "binary",
+    "url": "https://static.rust-lang.org/rustup/archive/1.29.2/{{.Arch}}-{{.OS}}/rustup-init",
+    "checksum": { "type": "sha256_url", "url": "{{.URL}}.sha256" },
+    "bin_name": "rustup-init"
+  },
+
+  "hooks": {
+    "post_install": [
+      // Installs rustup and its proxies (cargo, rustc, ...) into bin/ and
+      // the toolchain into the shared RUSTUP_HOME.
+      "RUSTUP_HOME=\"{{ .CacheDir }}/rustup\" CARGO_HOME=\"$DEVBOX_PKG_INSTALL_DIR\" RUSTUP_INIT_SKIP_PATH_CHECK=yes ./bin/rustup-init -y --no-modify-path --profile minimal --component rustfmt,clippy --default-toolchain {{.Version}}"
+    ]
+  },
+
+  "bin": ["bin"],
+  "binaries": ["rustup", "rustc", "cargo", "rustfmt", "cargo-clippy"],
+
+  "env": {
+    "RUSTUP_HOME": "{{ .CacheDir }}/rustup",
+    "RUSTUP_TOOLCHAIN": "{{ .Version }}"
+  }
+}
diff --git a/pkgs/terraform/terraform.pkg.jsonc b/pkgs/terraform/terraform.pkg.jsonc
new file mode 100644
index 00000000000..bf6eeca32fe
--- /dev/null
+++ b/pkgs/terraform/terraform.pkg.jsonc
@@ -0,0 +1,29 @@
+// Package definition for Terraform, installed from releases.hashicorp.com.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "terraform",
+  "description": "Infrastructure as code tool",
+  "homepage": "https://www.terraform.io",
+  "license": "BUSL-1.1",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+
+  "versions": {
+    "type": "http_json",
+    "url": "https://releases.hashicorp.com/terraform/index.json",
+    "select": ".versions | keys[]"
+  },
+
+  "install": {
+    "type": "archive",
+    "url": "https://releases.hashicorp.com/terraform/{{.Version}}/terraform_{{.Version}}_{{.OS}}_{{.Arch}}.zip",
+    "checksum": {
+      "type": "sha256_url",
+      "url": "https://releases.hashicorp.com/terraform/{{.Version}}/terraform_{{.Version}}_SHA256SUMS"
+    }
+  },
+
+  "bin": ["."],
+  "binaries": ["terraform"]
+}
diff --git a/pkgs/uv/uv.pkg.jsonc b/pkgs/uv/uv.pkg.jsonc
new file mode 100644
index 00000000000..633c053cfda
--- /dev/null
+++ b/pkgs/uv/uv.pkg.jsonc
@@ -0,0 +1,27 @@
+// Package definition for uv, installed from its GitHub releases.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "uv",
+  "description": "An extremely fast Python package and project manager",
+  "homepage": "https://docs.astral.sh/uv",
+  "license": "MIT OR Apache-2.0",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+  // Rust target triples.
+  "os_map": { "darwin": "apple-darwin", "linux": "unknown-linux-gnu" },
+  "arch_map": { "x86_64": "x86_64", "aarch64": "aarch64" },
+
+  // Tags have no "v" prefix.
+  "versions": { "type": "github_releases", "repo": "astral-sh/uv", "strip_prefix": "" },
+
+  "install": {
+    "type": "archive",
+    "url": "https://github.com/astral-sh/uv/releases/download/{{.Version}}/uv-{{.Arch}}-{{.OS}}.tar.gz",
+    "checksum": { "type": "sha256_url", "url": "{{.URL}}.sha256" },
+    "strip_components": 1
+  },
+
+  "bin": ["."],
+  "binaries": ["uv", "uvx"]
+}
diff --git a/pkgs/yarn/yarn.pkg.jsonc b/pkgs/yarn/yarn.pkg.jsonc
new file mode 100644
index 00000000000..8634ccc1fb8
--- /dev/null
+++ b/pkgs/yarn/yarn.pkg.jsonc
@@ -0,0 +1,54 @@
+// Package definition for Yarn, installed from the npm registry. Yarn is
+// JavaScript, so the project also needs nodejs.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "yarn",
+  "description": "Package manager for JavaScript",
+  "homepage": "https://yarnpkg.com",
+  "license": "BSD-2-Clause",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+
+  // Yarn 2 and later ("berry") is published as @yarnpkg/cli-dist; Yarn 1
+  // ("classic") stays in the yarn package.
+  "versions": [
+    {
+      "type": "http_json",
+      "url": "https://registry.npmjs.org/@yarnpkg/cli-dist",
+      "select": ".versions | keys[]"
+    },
+    {
+      "type": "http_json",
+      "url": "https://registry.npmjs.org/yarn",
+      "select": ".versions | keys[]"
+    }
+  ],
+
+  "install": {
+    "type": "archive",
+    "url": "https://registry.npmjs.org/@yarnpkg/cli-dist/-/cli-dist-{{.Version}}.tgz",
+    "checksum": {
+      "type": "http_json",
+      "url": "https://registry.npmjs.org/@yarnpkg/cli-dist/{{.Version}}",
+      "select": ".dist.integrity"
+    },
+    "strip_components": 1,
+    "version_overrides": [
+      {
+        "versions": "<2",
+        "url": "https://registry.npmjs.org/yarn/-/yarn-{{.Version}}.tgz",
+        "checksum": {
+          "type": "http_json",
+          "url": "https://registry.npmjs.org/yarn/{{.Version}}",
+          "select": ".dist.integrity"
+        }
+      }
+    ]
+  },
+
+  "bin": ["bin"],
+  // The berry tarball ships bin/yarn without the executable bit; listing
+  // it here has Devbox set it.
+  "binaries": ["yarn"]
+}
diff --git a/pkgs/zig/zig.pkg.jsonc b/pkgs/zig/zig.pkg.jsonc
new file mode 100644
index 00000000000..0f4f106a4eb
--- /dev/null
+++ b/pkgs/zig/zig.pkg.jsonc
@@ -0,0 +1,35 @@
+// Package definition for Zig, installed from ziglang.org.
+// Format: see specs/package-definitions.md.
+{
+  "schema": 1,
+  "name": "zig",
+  "description": "General-purpose programming language and toolchain",
+  "homepage": "https://ziglang.org",
+  "license": "MIT",
+
+  "platforms": ["aarch64-darwin", "x86_64-darwin", "aarch64-linux", "x86_64-linux"],
+  "os_map": { "darwin": "macos", "linux": "linux" },
+  "arch_map": { "x86_64": "x86_64", "aarch64": "aarch64" },
+
+  // index.json is keyed by version, plus a "master" entry for nightlies.
+  "versions": {
+    "type": "http_json",
+    "url": "https://ziglang.org/download/index.json",
+    "select": "keys[] | select(. != \"master\")"
+  },
+
+  // The index has the tarball URL and its sha256 per platform. Tarball
+  // names changed in 0.14 ("zig-macos-aarch64" became
+  // "zig-aarch64-macos"), which the lookup absorbs.
+  "install": {
+    "type": "archive",
+    "lookup": {
+      "url": "https://ziglang.org/download/index.json",
+      "select": ".[\"{{.Version}}\"][\"{{.Arch}}-{{.OS}}\"] // empty | {url: .tarball, checksum: .shasum}"
+    },
+    "strip_components": 1
+  },
+
+  "bin": ["."],
+  "binaries": ["zig"]
+}
diff --git a/specs/package-definitions.md b/specs/package-definitions.md
index 7bb998ec1ec..bfe69b92556 100644
--- a/specs/package-definitions.md
+++ b/specs/package-definitions.md
@@ -8,8 +8,9 @@ lands.
 
 Let a Devbox project install a tool from the upstream vendor's own binary
 distribution (go.dev, nodejs.org, GitHub releases, ...) instead of nixpkgs,
-driven by a small declarative *package definition* file. Go is the first
-package (see [`pkgs/go/go.pkg.jsonc`](../pkgs/go/go.pkg.jsonc)). Later, the
+driven by a small declarative *package definition* file. Go was the first
+package (see [`pkgs/go/go.pkg.jsonc`](../pkgs/go/go.pkg.jsonc)); the initial
+set of 16 is listed under [Shipped packages](#shipped-packages). Later, the
 search service returns these definitions so that `devbox add go@1.22`
 transparently picks the vendor build.
 
@@ -130,25 +131,38 @@ hatch.
 | `description`, `homepage`, `license` | no | Informational. `homepage` is shown by `devbox info`. |
 | `platforms` | yes | Non-empty list of nix system names the definition supports. |
 | `os_map`, `arch_map` | no | Overrides for the `{{.OS}}` and `{{.Arch}}` template variables. Keys are the nix OS (`darwin`, `linux`) and nix arch (`x86_64`, `aarch64`). |
-| `versions` | yes | A version source. See below. |
+| `versions` | yes | A version source, or a list of them. See below. |
 | `install` | yes | An install strategy. See below. |
 | `bin` | no | Directories relative to the install root that go on `PATH`. Default `["bin"]`. |
-| `binaries` | no | Executable names expected on `PATH` after install. |
+| `binaries` | no | Executable names expected in a `bin` directory after install. Install marks them executable (npm tarballs drop the bit) and fails if one is missing. |
 | `env`, `shell`, `create_files` | no | Plugin-compatible activation. See Activation. |
-| `hooks.post_install` | no | Shell commands run once per installed version. |
+| `hooks.post_install` | no | Shell commands run once per installed version by `/bin/sh` in the install root, with `DEVBOX_PKG_INSTALL_DIR`, `DEVBOX_PKG_VERSION` and `DEVBOX_PKG_SYSTEM` set and `/usr/bin:/bin` appended to `PATH`. |
 
 ### Version sources (`versions`)
 
 | `type` | Fields | Behaviour |
 |---|---|---|
 | `static` | `versions: [string]` | The list is the universe of versions. |
-| `http_json` | `url`, `select` | GET `url`, parse JSON, evaluate the jq expression in `select`. Every string (or number) it emits is a version. |
-| `github_releases` | `repo` (`owner/name`), `strip_prefix` (default `"v"`) | List releases through the GitHub API, skip drafts and pre-releases, strip the prefix from tag names. Honors `GITHUB_TOKEN`. |
+| `http_json` | `url`, `select` | GET `url`, parse JSON, evaluate the jq expression in `select`. Every string (or number) it emits is a version. When `url` contains `{{.Page}}`, pages 0, 1, ... are fetched until one returns 404 or no versions. |
+| `github_releases` | `repo` (`owner/name`), `strip_prefix` (default `"v"`) | List releases through the GitHub API, 100 per page, skip drafts and pre-releases, strip the prefix from tag names. Honors `GITHUB_TOKEN`. |
 | `script` | `run` | Planned. Run `run` with `sh -c`; one version per output line. |
 
+`versions` may also be a list of sources, whose versions are combined. Yarn
+needs this: 1.x is the `yarn` npm package and 2.x onward is
+`@yarnpkg/cli-dist`.
+
+Paginated sources (`github_releases`, and `http_json` with `{{.Page}}`) are
+read lazily: resolution stops at the first page that has a version matching
+the request, so `latest` costs one request and `kubectl@1.30` reads as many
+pages as it takes to reach 1.30. Sources should list newest versions first.
+At most 20 pages are read.
+
 Version strings are compared as dotted numeric segments, falling back to
-string comparison. Versions containing a hyphen (`1.23.0-rc1`) are treated as
-pre-releases and only match when requested exactly.
+string comparison. Build metadata after `+` (OpenJDK's `21.0.5+11`) only
+breaks ties, so a vendor respin (`21.0.12+101`) sorts after the original
+build (`21.0.12+8`). Versions whose part before `+` contains a hyphen or a
+letter (`1.23.0-rc1`, `3.14.0a1`) are pre-releases and only match when
+requested exactly.
 
 Matching a requested version against the list:
 
@@ -157,21 +171,77 @@ Matching a requested version against the list:
 | `latest` | The highest non-pre-release version. |
 | `1.22` | The highest version equal to `1.22` or starting with `1.22.`. |
 | `1.22.3` | That version exactly (also by the prefix rule, so `1.22.3` matches `1.22.3.1`-style versions if the exact one is absent). |
+| `21.0.5` | The highest `21.0.5+<build>`. |
 
 ### Install strategies (`install`)
 
-`install.type` picks how a version lands on disk. `install.overrides` is a
-map from nix system to a partial `install` object whose fields replace the
-defaults for that system (for example a different `url` or `strip_components`
-on one platform).
+`install.type` picks how a version lands on disk.
 
 | `type` | Fields | Behaviour |
 |---|---|---|
-| `archive` | `url`, `checksum`, `strip_components` (default `0`) | Download the archive, verify it, extract it into the install root. Supports `.tar.gz`, `.tgz`, `.tar.xz`, `.tar.bz2`, `.tar.zst` and `.zip`. |
-| `binary` | `url`, `checksum`, `bin_name` (default: `name`) | Download a single executable to `<root>/bin/<bin_name>` and mark it executable. |
+| `archive` | `url` and `checksum`, or `lookup`; `strip_components` (default `0`) | Download the archive, verify it, extract it into the install root. Supports `.tar.gz`, `.tgz`, `.tar.xz`, `.tar.bz2`, `.tar.zst` and `.zip`. |
+| `binary` | `url` and `checksum`, or `lookup`; `bin_name` (default: `name`) | Download a single executable to `<root>/bin/<bin_name>` and mark it executable. |
 | `manager` | `requires`, `env`, `install`, `locate` | Planned. Delegate to another definition that owns version management (see below). |
 | `script` | `run` | Planned. Escape hatch: run `run` with the install root as `$DEVBOX_PKG_INSTALL_DIR`. |
 
+#### Looking up the artifact in an index (`install.lookup`)
+
+Some vendors' download names can't be derived from the version:
+python-build-standalone puts a build date in every file name, Temurin renames
+respins (`21.0.12+101` ships as `..._21.0.12.1_1.tar.gz`), and zig renamed
+its tarballs in 0.14. Their indexes list the exact URL and checksum instead.
+`lookup` replaces `url` and `checksum`:
+
+```jsonc
+"install": {
+  "type": "archive",
+  "lookup": {
+    "url": "https://ziglang.org/download/index.json",
+    "select": ".[\"{{.Version}}\"][\"{{.Arch}}-{{.OS}}\"] // empty | {url: .tarball, checksum: .shasum}"
+  }
+}
+```
+
+`url` and `select` are templates. `select` is a jq expression that must
+produce an object with `url` and, optionally, `checksum` (any digest format
+below). If it produces nothing, or `url` returns 404, the vendor has no
+artifact of that version for that system.
+
+#### Overrides
+
+`install.overrides` maps a nix system to a partial `install` object whose
+fields replace the defaults for that system (for example a different
+`strip_components` for macOS bundles).
+
+`install.version_overrides` is a list of partial `install` objects for vendors
+that changed how they ship artifacts. Each has a `versions` constraint: one or
+more comparisons with `<`, `<=`, `>`, `>=`, `=` or `!=`, separated by spaces
+or commas, that must all hold (`"<11"`, `">=2, <4"`). A bare version matches
+itself and every more specific version. The first entry that matches applies.
+An entry may have its own `overrides` per system but no nested
+`version_overrides`.
+
+```jsonc
+"install": {
+  "type": "archive",
+  "url": "https://github.com/pnpm/pnpm/releases/download/v{{.Version}}/pnpm-{{.OS}}-{{.Arch}}.tar.gz",
+  "checksum": { "type": "github_release", "repo": "pnpm/pnpm" },
+  "version_overrides": [
+    {
+      "versions": "<11",
+      "url": "https://registry.npmjs.org/@pnpm/{{ .OS | replace \"darwin\" \"macos\" }}-{{.Arch}}/-/...",
+      "checksum": { "type": "http_json", "url": "...", "select": ".dist.integrity" },
+      "strip_components": 1
+    }
+  ]
+}
+```
+
+Overrides apply in this order: the matching version override, the
+definition's override for the system, then the version override's own
+override for the system. `url` and `lookup` are alternatives, so an override
+that sets one clears the other.
+
 Why two real strategies: `archive` covers more than it first appears. Go,
 nodejs, deno, bun, zig, Temurin JDK and python (via python-build-standalone,
 the same builds uv installs) all ship per-platform archives, so fnm, nvm and
@@ -179,6 +249,11 @@ pyenv are not needed for them. `manager` is for ecosystems where the vendor
 ships no usable archive or the manager is the ecosystem's contract: rustup
 for rust, ruby (no official binaries), php on Linux.
 
+Until `manager` exists, the shipped `rust` definition gets the same result
+with `binary` plus a `post_install` hook: it installs the checksummed
+`rustup-init` and runs it to install the requested toolchain into a shared
+`RUSTUP_HOME`, and its `env` sets `RUSTUP_TOOLCHAIN` to the version.
+
 A manager-backed definition will look like this once implemented:
 
 ```jsonc
@@ -217,14 +292,33 @@ verification through sum.golang.org, so it stays an alternate definition.
 
 | `type` | Fields | Behaviour |
 |---|---|---|
-| `http_json` | `url`, `select` | GET `url`, evaluate the jq expression; the first string result is the hex sha256. |
+| `http_json` | `url`, `select` | GET `url`, evaluate the jq expression; the first string result is the digest. Covers JSON indexes and the npm registry's `dist.integrity`. |
 | `sha256_url` | `url` | GET `url`. The body is either a bare hex digest or a `sha256sum`-style list (`<hex>  <filename>` per line) matched by `{{.Filename}}`. Covers nodejs `SHASUMS256.txt` and the common `<asset>.sha256` convention. |
+| `sha512_url` | `url` | Like `sha256_url` for sha512 digests (Apache's `.sha512` files). |
+| `github_release` | `repo`, `tag` (default `v{{.Version}}`) | The digest GitHub computes for every release asset, read through the GitHub API (honors `GITHUB_TOKEN`). Assets uploaded before GitHub started computing digests (mid 2025) have none, which is treated like `none`. |
 | `none` | | No vendor-published checksum. `devbox add` records the digest it observes for the current system (trust on first use). Other systems are filled in lazily when a machine of that system installs, matching how nix store paths are backfilled today. |
 
+Digests may be sha256 or sha512, as hex (the algorithm follows from the
+length), as `sha256:<hex>`/`sha512:<hex>`, or as an SRI string
+(`sha512-<base64>`).
+
 Checksums are mandatory when installing from an existing lockfile entry: the
-downloaded artifact must match the `sha256` recorded for the system, or the
+downloaded artifact must match the digest recorded for the system, or the
 install fails.
 
+#### Platforms a version is not published for
+
+Vendors add and drop platforms over time: Node.js had no Apple silicon
+build before 16, Java 8 has none at all, Temurin 27 has no Intel macOS
+build. When the checksum source shows that an artifact does not exist (the
+checksum file or lookup index returns 404, a checksum list has no entry for
+the file, a jq expression matches nothing, the GitHub release has no such
+asset), that system is left out of the lock entry. Locking fails only when no
+platform has an artifact. Installing on a system that the lock entry leaves
+out fails with an error that names the platforms the version is available
+for. Definitions with checksum `none` cannot tell, so their lock entries
+list every platform.
+
 ### Template variables
 
 Templates use Go `text/template` with `missingkey=error`. Available
@@ -238,10 +332,13 @@ variables:
 | `{{.URL}}`, `{{.Filename}}` | `checksum`, `hooks` | The rendered artifact URL and its last path segment. |
 | `{{.InstallDir}}` | `env`, `shell`, `create_files`, `hooks` | Install root for this version and system. |
 | `{{.CacheDir}}` | `env`, `shell`, `hooks`, `install.env` | `$XDG_CACHE_HOME/devbox/pkgs`. |
+| `{{.Page}}` | `versions.url` (`http_json`) | The 0-based page number. See Version sources. |
 
-Functions: `trimPrefix`, `trimSuffix`, `replace`, `lower`, `upper`. Arguments
-follow the sprig order with the string last, so pipelines read naturally:
-`{{ .Version | trimPrefix "v" }}`, `{{ replace "." "_" .Version }}`.
+Functions: `trimPrefix`, `trimSuffix`, `replace`, `lower`, `upper`,
+`splitList`, plus the `text/template` builtins (`eq`, `index`, `urlquery`,
+...). Arguments follow the sprig order with the string last, so pipelines read
+naturally: `{{ .Version | trimPrefix "v" }}`, `{{ replace "." "_" .Version }}`,
+`{{ index (splitList "." .Version) 0 }}` for the major version.
 
 ### Activation
 
@@ -284,8 +381,11 @@ for every install strategy.
   refuses to install from a definition whose hash differs. For local
   definitions it is informational; edits are picked up through the state
   hash and trigger a reinstall.
-- `systems.*.url` and `systems.*.sha256` are new `omitempty` fields on the
-  existing per-system struct. `lockfile_version` stays `1`.
+- `systems.*.url`, `systems.*.sha256` and `systems.*.sha512` are new
+  `omitempty` fields on the existing per-system struct. `lockfile_version`
+  stays `1`.
+- A system missing from `systems` means the vendor does not publish this
+  version for it.
 - Older Devbox binaries reject the `pkg:` package string. Projects that adopt
   package definitions should set `devbox_version` in `devbox.json`.
 
@@ -295,8 +395,9 @@ cache. Garbage collection of unused versions is a follow-up
 (`devbox cache gc`).
 
 Each install directory carries a marker with the *install fingerprint* of
-the definition: a hash of the install strategy, `bin`, `hooks`, `os_map`
-and `arch_map`. When a definition's install recipe changes for a version
+the definition: a hash of the install strategy that applies to the version
+and system (after overrides), `bin`, `binaries`, `hooks`, `os_map` and
+`arch_map`. When a definition's install recipe changes for a version
 that is already installed, the next install redoes it. Activation-only
 edits (`env`, `shell`, `create_files`) do not trigger a reinstall; they are
 applied at shell time.
@@ -305,6 +406,36 @@ Trust-on-first-use digests are written to `devbox.lock` only by the install
 step (`devbox add`, `devbox install`, `devbox update`), never while
 computing the environment for `devbox shell` or `devbox shellenv`.
 
+## Shipped packages
+
+Definitions live in `pkgs/<name>/<name>.pkg.jsonc`, each next to a
+testscript (`<name>.test.txt`) that installs two versions and switches
+between them. All of them support the four platforms; a version a vendor does
+not publish for a platform is skipped for it (see above).
+
+| Package | Source | Versions from | Checksum | Notes |
+|---|---|---|---|---|
+| `go` | go.dev | go.dev JSON index | index (`http_json`) | Sets `GOTOOLCHAIN=local` like the nixpkgs go, so the pinned version runs even when go.mod asks for a newer one. |
+| `nodejs` | nodejs.org | `index.json` | `SHASUMS256.txt` | Includes npm (and corepack before 25). `npm install -g` goes to the project's virtenv. |
+| `pnpm` | GitHub releases (11+), npm `@pnpm/<os>-<arch>` (<11) | GitHub releases | GitHub asset digest; npm sha512 integrity | Standalone executable with its own Node.js. `version_overrides` for the layout change in 11. |
+| `yarn` | npm `@yarnpkg/cli-dist` (2+), `yarn` (1.x) | both npm packages (list of sources) | npm sha512 integrity | Needs `nodejs`. `binaries` restores the executable bit npm drops. |
+| `python` | python-build-standalone | uv's `download-metadata.json` | index (`lookup`) | Creates and activates `$VENV_DIR` (default `.venv`), recreating it when the version changes, so pip never writes to the shared install. |
+| `uv` | GitHub releases | GitHub releases | `<asset>.sha256` | |
+| `rust` | static.rust-lang.org (rustup-init) | rust-lang/rust GitHub releases | `rustup-init.sha256`, then rustup's manifest | `post_install` runs rustup-init; toolchains share `RUSTUP_HOME` in the cache; `RUSTUP_TOOLCHAIN` selects the version. |
+| `java` | Adoptium (Eclipse Temurin JDK) | Adoptium API, paged | index (`lookup`) | Versions are `21.0.5+11`. `JAVA_HOME` is set. macOS builds are bundles, hence a per-system `strip_components`. |
+| `gradle` | services.gradle.org | `versions/all` | index (`http_json`) | Needs `java`. |
+| `maven` | Maven Central | Maven Central search API | Apache archive `.sha512` | Needs `java`. Central has digests for only some releases. |
+| `deno` | GitHub releases | GitHub releases | `<asset>.sha256sum` | Releases before 2.0.1 have no checksum (trust on first use). |
+| `bun` | GitHub releases | GitHub releases | `SHASUMS256.txt` | `post_install` links `bunx`. |
+| `zig` | ziglang.org | `index.json` | index (`lookup`) | |
+| `terraform` | releases.hashicorp.com | `index.json` | `SHA256SUMS` | |
+| `kubectl` | dl.k8s.io | kubernetes/kubernetes GitHub releases | `<binary>.sha256` | |
+| `helm` | get.helm.sh | helm/helm GitHub releases | `<asset>.sha256sum` | |
+
+Not shipped yet: ruby and php (no official binaries; `manager`), dotnet,
+erlang/elixir, and tools that are a one-line `binary` definition each (gh,
+jq, just, ...).
+
 ## Security
 
 The trust model equals plugins today: a definition is remote JSON that can
@@ -367,6 +498,38 @@ flag is off, `pkg:` strings are not recognized at all.
 - A definition whose `platforms` exclude the current system fails at
   install time with a hint to use `--exclude-platform`.
 
+### PR 4: initial package set
+
+- `pkgs/<name>/<name>.pkg.jsonc` for the packages in
+  [Shipped packages](#shipped-packages).
+- This spec: lists of version sources, paginated sources, versions with
+  `+build`, `install.lookup`, `install.version_overrides`, `sha512_url` and
+  `github_release` checksums, sha512 and SRI digests, platforms a version is
+  not published for, and `binaries` checks.
+
+### PR 5: support for the initial package set
+
+- `internal/pkgdef`: everything listed under PR 4, plus memoized metadata
+  requests so locking four platforms fetches an index once, `/bin/sh` and a
+  fallback `PATH` for hooks, and an install fingerprint per version.
+- `lock.SystemInfo.Sha512`; lock entries omit systems without an artifact,
+  and installing on such a system is an error that lists where the version
+  is available.
+- `ensureStateIsUpToDate` reloads plugin configs after installing, so a
+  version changed in devbox.json gets its definition's env and init hook in
+  the same run.
+
+### PR 6: tests for the initial package set
+
+- `pkgs/<name>/<name>.test.txt`: install a version from devbox.json, switch
+  with `devbox add`, switch back by editing devbox.json, checking the
+  version (and env) each time. Run by `TestPackageDefinitions` when
+  `DEVBOX_RUN_PKGDEF_TESTS=1`, and by a CI workflow on Linux and macOS when
+  `pkgs/` or the implementation changes and weekly to catch vendor changes.
+- Every shipped definition parses and is named after its directory (always
+  runs); every shipped definition resolves `latest` and locks it against the
+  real vendor (network, same flag).
+
 ### Later
 
 - Search service: `/v2/resolve` returns `source: "pkg-def"` plus the
@@ -389,6 +552,18 @@ flag is off, `pkg:` strings are not recognized at all.
   entry today because canonical names differ (`pkg:./go.pkg.jsonc` vs `go`).
   Decide whether it should once search returns definitions.
 - `devbox global` shares `computeEnv` and should work unchanged; verify.
+- Vendor metadata is a dependency: python's index is a file in uv's
+  repository (it moved once already), Java depends on the Adoptium API, and
+  Maven on search.maven.org. A broken source fails `devbox add` and
+  `devbox update` only; locked projects keep installing from the recorded
+  URLs. The weekly CI run is the early warning; the search service could
+  serve these indexes later.
+- Version lookups through the GitHub API are limited to 60 requests an hour
+  without `GITHUB_TOKEN`. Pagination is lazy and responses are memoized, so a
+  typical `devbox add` makes one or two requests.
+- Hooks run with the user's environment. The rust definition depends on
+  rustup-init flags staying compatible; the `manager` strategy would make
+  that contract explicit.
 - Windows and `devbox generate` images are out of scope for the first cut.
 
 ## Status
@@ -401,6 +576,9 @@ flag is off, `pkg:` strings are not recognized at all.
 | Lockfile fields `definition_hash`, `systems.*.url`, `systems.*.sha256` | in review (PR 3) |
 | Activation through the plugin manager (`env`, `shell`, `create_files`) | in review (PR 3) |
 | Trust-on-first-use checksum recording | in review (PR 3) |
+| Initial package set (16 definitions) | in review (PR 4) |
+| `lookup`, `version_overrides`, version source lists, pagination, sha512, `github_release` checksums, per-platform availability | in review (PR 5) |
+| Per-package install and version-switch tests, CI workflow | in review (PR 6) |
 | `manager` strategy | not started |
 | `script` strategy | not started |
 | `github:` refs | not started |