Oh My Zsh native plugin loader vs zplug: which should own plugin sourcing when both are configured?

Direct Answer

Let Oh My Zsh own every plugin that lives in its own repository (built-ins and custom/plugins), and let zplug manage only third-party plugins that are not present in Oh My Zsh. Place zplug load after source $ZSH/oh-my-zsh.sh. If a plugin exists in both ecosystems (e.g., zsh-autosuggestions), pick one source—prefer the upstream repo via zplug—and remove it from the other side.

Why This Partition Works

No official convention, but a clear de facto practice

Oh My Zsh documents no policy on external managers. The community pattern that avoids surprises is: Oh My Zsh = framework plugins; zplug = everything else. Oh My Zsh loads its plugins array in order, checking ~/.oh-my-zsh/custom/plugins/<name> before ~/.oh-my-zsh/plugins/<name>. It performs no dependency resolution or deduplication.

Duplicate sourcing causes real problems, not just slower startup

When the same plugin file is sourced twice (once by Oh My Zsh, once by zplug):

• Hook functions (precmd, preexec, chpwd) are re-registered, so they run multiple times per prompt.
• PATH modifications and alias/function definitions are re-applied, potentially doubling PATH entries or overriding intended behavior.
• Plugin internal state (arrays, associative arrays) may be reset mid-session, breaking features that rely on persistent state.

These are not theoretical; they appear immediately in $precmd_functions, $preexec_functions, and $path.

Custom overrides stay with Oh My Zsh unless you deliberately migrate

~/.oh-my-zsh/custom/plugins/<name> remains under Oh My Zsh control. Migrating to zplug is optional but requires:

1. Change the source to a local path: zplug "~/.oh-my-zsh/custom/plugins/<name>", from:local
2. Remove the name from the plugins array to prevent double load

If you keep the override in custom/plugins, Oh My Zsh continues to load it; zplug simply ignores that name.

Minimal Safe Configuration

# .zshrc
plugins=(git docker kubectl)  # only Oh My Zsh built-ins or custom/plugins

source $ZSH/oh-my-zsh.sh

# zplug manages ONLY external repos not in Oh My Zsh
zplug "zsh-users/zsh-autosuggestions"
zplug "zsh-users/zsh-syntax-highlighting", defer:2
zplug "junegunn/fzf", as:command, use:bin/fzf-tmux

zplug load

One Diagnostic to Confirm Your Setup

Run this once to verify no plugin is sourced twice:

zsh -x -i -c exit 2>&1 | grep -E '(source|\. ).*/(plugins|zplug)/' | sort -u

If any plugin path appears twice, adjust the partition. Which plugin(s) are you currently listing in both the plugins array and zplug? That single list will tell me whether the recommendation needs to change for your case.