Adding tools to Pocket

A Pocket "tool" is a reusable binary or package that Pocket downloads, installs, and makes available. Each tool owns its complete lifecycle: version definition, installation, and execution.

Directory structure

code

tools/<toolname>/
├── <toolname>.go        # Package with Name, Version, Install task
├── pyproject.toml       # (Python tools)
├── uv.lock              # (Python tools)
├── package.json         # (Node tools)
└── bun.lock             # (Node tools)

Required exports

Every tool package must export:

•Name constant (the binary name)
•Version constant or Version() function
•Install variable (*pk.Task, hidden + global)

Version specification

Use inline constants with Renovate comments for automatic updates:

// renovate: datasource=github-releases depName=owner/repo
const Version = "1.2.3"

For tools with lockfiles (Python/Node), use the ecosystem's ContentHash:

// Python tools:
func Version() string {
    return uv.ContentHash(pyprojectTOML, uvLock, []byte(uv.DefaultPythonVersion))
}

// Node tools:
func Version() string {
    return bun.ContentHash(packageJSON, lockfile)
}

Install task pattern

var Install = &pk.Task{
    Name:   "install:<tool-name>",
    Usage:  "install <tool-name>",
    Body:   installFunc(),  // or golang.Install(...) for Go tools
    Hidden: true,           // internal, not shown in CLI help
    Global: true,           // run once total, not per-path
}

Installation patterns

Choose the pattern that matches your tool. See PATTERNS.md for complete examples of each pattern.

Pattern 1: Go package (`go install`)

For tools written in Go. Simplest pattern.

Body: golang.Install("github.com/org/tool/cmd/tool", Version),

Pattern 2: GitHub release binary

For pre-compiled binaries. The pk/download package provides helper functions for downloading, extracting archives, and making the binary available in Pocket (symlink into .pocket/bin/). Use download.Download with platform-aware URLs. Must handle platform/arch mapping (see cross-platform section in PATTERNS.md).

Pattern 3: Python tool (via uv)

For Python tools. Depends on uv.Install. Uses pyproject.toml/uv.lock with uv.Sync for reproducible, locked builds. Uses uv.ContentHash for directory naming and uv.ExecTool for execution (avoids shebang issues). Exposes an Exec() function instead of a symlink.

Pattern 4: Node tool (via bun)

For Node.js tools. Depends on bun.Install. Embeds package.json and bun.lock via //go:embed. Uses bun.ContentHash for directory naming. Exposes an Exec() function instead of a symlink.

Ecosystem tools (uv, bun)

The uv and bun packages are themselves tools (with their own Install tasks) but also serve as ecosystems for other tools. When your tool depends on one of these, chain installation with pk.Serial:

Body: pk.Serial(uv.Install, installMyTool()),
// or
Body: pk.Serial(bun.Install, installMyTool()),

These ecosystem tools provide helper functions for creating venvs, installing packages, and running commands. See PATTERNS.md for details.

uv and Python version coupling

uv bundles Python download metadata at build time. This means the uv version must be recent enough to know about DefaultPythonVersion. If DefaultPythonVersion is updated (e.g. by Renovate) to a Python release that postdates the bundled uv version, uv sync --python <version> will fail on fresh environments (like CI) with:

code

error: No interpreter found for Python X.Y.Z in managed installations or search path

It may appear to work locally if that Python version was previously downloaded by a newer uv. When updating either version, verify the other is compatible. Run uv python list --only-downloads | grep <version> to confirm the uv binary knows about the target Python version.

Cross-platform support

All tools must support Linux, macOS, and Windows. Key considerations:

•Use pk.HostOS() and pk.HostArch() for platform detection
•Use pk.BinaryName(name) to append .exe on Windows
•Use pk.DefaultArchiveFormat() ("zip" on Windows, "tar.gz" otherwise)
•Release URL naming varies per project (see PATTERNS.md for mapping examples)
•download.WithSymlink() automatically copies instead of symlinking on Windows
•bun on Windows requires extra care (see PATTERNS.md)

Making the tool available

Two approaches depending on tool type:

Symlinked binaries (native/Go tools): Use download.WithSymlink() or download.CreateSymlink(). The binary is symlinked into .pocket/bin/ which is on PATH during task execution. Invoke with pk.Exec(ctx, Name, args...).

Exec function (Python/Node tools): No symlink. Expose a public Exec(ctx, args...) function that invokes the tool through its runtime.

Wiring the tool into a task

var Lint = &pk.Task{
    Name:  "lint",
    Usage: "run linter",
    Body: pk.Serial(
        mytool.Install,
        pk.Do(func(ctx context.Context) error {
            return pk.Exec(ctx, mytool.Name, "run", "./...")
        }),
    ),
}

Idempotency

Always wrap installation logic so it skips if the tool already exists:

// For download-based tools (native binaries):
download.WithSkipIfExists(binaryPath)

// For Python/uv tools — use EnsureInstalled (checks binary + Python interpreter):
uv.EnsureInstalled(venvDir, name, func(ctx context.Context) error {
    // ... create venv, install packages ...
})

// For Node/bun tools — use EnsureInstalled (checks binary in node_modules/.bin/):
bun.EnsureInstalled(installDir, name, func(ctx context.Context) error {
    // ... write lockfiles, bun install ...
})

EnsureInstalled wraps your install function with the correct idempotency check. Use it instead of manual os.Stat or IsInstalled checks — it makes the correct pattern impossible to forget.

For Python/uv tools, EnsureInstalled verifies both the tool binary and the venv's Python interpreter exist. This guards against stale CI caches where script files remain but the shebang interpreter is missing.

Checklist

•Create tools/<name>/<name>.go with Name, Version, Install
•Add Renovate comment on version constant/variable
•Handle all three platforms (Linux, macOS, Windows)
•Ensure idempotent installation (skip if exists)
•Set Hidden: true and Global: true on the Install task
•Wire into a task via pk.Serial(tool.Install, ...)
•Run go mod tidy in .pocket/