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Detection Priority

Pumu automatically detects the package manager in each project by scanning for specific lockfiles and manifest files. The detection happens in a priority order to handle projects with multiple package managers.

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Priority Order

When multiple lockfiles exist in the same directory, Pumu uses this priority order (from detector.go:28-37):
  1. Bun - bun.lockb or bun.lock
  2. pnpm - pnpm-lock.yaml
  3. Yarn - yarn.lock
  4. npm - package-lock.json
  5. Deno - deno.json or deno.jsonc
  6. Cargo - Cargo.toml
  7. Go - go.mod
  8. Pip - requirements.txt or pyproject.toml
The priority order ensures that if you have both package-lock.json and pnpm-lock.yaml in the same directory, Pumu will recognize it as a pnpm project.

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Supported Package Managers

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JavaScript/TypeScript Ecosystems

Detection Files:
  • package-lock.json
Dependency Folder:
  • node_modules/
Typical Size:
  • 50-500+ MB
Install Command:
npm install

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Other Languages

Detection Files:
  • Cargo.toml
Dependency Folder:
  • target/
Typical Size:
  • 100-2000+ MB (build artifacts and dependencies)
Build Command:
cargo build

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Dependency Folders by Package Manager

Pumu tracks these dependency and build folders (from scanner.go:34-37):
FolderPackage Manager(s)Typical SizeDeletable
node_modulesnpm, pnpm, yarn, bun, deno50-500+ MB✅
targetcargo100-2000+ MB✅
.venvpip50-300+ MB✅
.nextNext.js100-500+ MB✅
.svelte-kitSvelteKit50-200+ MB✅
distVarious build tools10-100+ MB✅
buildVarious build tools10-100+ MB✅
These folders are considered safe to delete because they can be regenerated from lockfiles and source code. However, always ensure your lockfiles are committed to version control.

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Multi-Package Manager Projects

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Monorepos

In monorepos, different packages may use different package managers. Pumu handles this by:
  1. Per-directory detection - Each subdirectory is scanned independently
  2. Separate reinstallation - Each project can be reinstalled with its own package manager
  3. Interactive selection - You choose which projects to reinstall
Example monorepo structure: 
monorepo/
├── frontend/
│   ├── package-lock.json  → npm
│   └── node_modules/      → deletable
├── backend/
│   ├── Cargo.toml         → cargo
│   └── target/            → deletable
└── scripts/
    ├── requirements.txt   → pip
    └── .venv/             → deletable
When you run pumu sweep --reinstall, you’ll see: 
📦 Select projects to reinstall:
▸ [✓] ./frontend (npm)
  [✓] ./backend (cargo)
  [✓] ./scripts (pip)

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Mixed Lockfiles

If a single directory contains multiple lockfiles (e.g., both package-lock.json and yarn.lock), Pumu uses the priority order to select one:
If you have both package-lock.json and pnpm-lock.yaml:
  1. Pumu detects pnpm (higher priority)
  2. Runs pnpm install during reinstall
  3. The package-lock.json is ignored
Best practice: Remove unused lockfiles to avoid confusion.
Folders like .next and .svelte-kit are always detected regardless of package manager:
  • They’re recognized by name, not by lockfiles
  • They’re safe to delete (regenerated on build)
  • They don’t affect package manager detection

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Detection Algorithm

The detection logic (from detector.go:27-48) works as follows: 
func DetectManager(dir string) PackageManager {
    managers := map[PackageManager][]string{
        Bun:   {"bun.lockb", "bun.lock"},
        Pnpm:  {"pnpm-lock.yaml"},
        Yarn:  {"yarn.lock"},
        Npm:   {"package-lock.json"},
        Deno:  {"deno.json", "deno.jsonc"},
        Cargo: {"Cargo.toml"},
        Go:    {"go.mod"},
        Pip:   {"requirements.txt", "pyproject.toml"},
    }

    for mgr, files := range managers {
        for _, f := range files {
            if fileExists(filepath.Join(dir, f)) {
                return mgr
            }
        }
    }

    return Unknown
}
The iteration order in Go maps is deterministic in this implementation because the priority is enforced by the order of keys in the managers map definition.

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Examples

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Detect Package Manager in Current Directory

pumu
Output: 
🔍 Detected package manager: pnpm
🗑️  Removing node_modules...
✅ Removed in 1.23s
📦 Running pnpm install...

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Scan Multi-Language Project

cd ~/my-fullstack-app
pumu sweep --reinstall
Output: 
🔎 Scanning for heavy dependency folders in '.'...
⏱️  Found 3 folders. Calculating sizes concurrently...

🗑️  Select folders to delete:
▸ [✓] ./frontend/node_modules       487.50 MB
  [✓] ./backend/target                1.23 GB
  [✓] ./ml-service/.venv              156.78 MB

📦 Select projects to reinstall:
▸ [✓] ./frontend (pnpm)
  [✓] ./backend (cargo)
  [✓] ./ml-service (pip)

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See Also

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