feat(system): support custom brew taps

docs/.vitepress/cli_commands.ts

@@ -319,6 +319,9 @@ export const commands: { [key: string]: Command } = {
   system: {
     hide: false,
     subcommands: {
+      brew: {
+        hide: false,
+      },
       install: {
         hide: false,
       },

docs/cli/index.md

@@ -166,6 +166,9 @@ Can also use `MISE_NO_HOOKS=1`
 - [`mise sync python [--pyenv] [--uv]`](/cli/sync/python.md)
 - [`mise sync ruby [--brew]`](/cli/sync/ruby.md)
 - [`mise system <SUBCOMMAND>`](/cli/system.md)
+- [`mise system brew <SUBCOMMAND>`](/cli/system/brew.md)
+- [`mise system brew tap [-n --dry-run] <TAP> [URL]`](/cli/system/brew/tap.md)
+- [`mise system brew untap [-n --dry-run] <TAPS>…`](/cli/system/brew/untap.md)
 - [`mise system install [FLAGS] [PACKAGE]…`](/cli/system/install.md)
 - [`mise system status [-J --json] [--missing]`](/cli/system/status.md)
 - [`mise system upgrade [FLAGS] [PACKAGE]…`](/cli/system/upgrade.md)

docs/cli/system.md

@@ -20,6 +20,7 @@ ever acted on when explicitly requested with `mise system install` (or
 
 ## Subcommands
 
+- [`mise system brew <SUBCOMMAND>`](/cli/system/brew.md)
 - [`mise system install [FLAGS] [PACKAGE]…`](/cli/system/install.md)
 - [`mise system status [-J --json] [--missing]`](/cli/system/status.md)
 - [`mise system upgrade [FLAGS] [PACKAGE]…`](/cli/system/upgrade.md)

docs/cli/system/brew.md

@@ -0,0 +1,15 @@
+<!-- @generated by usage-cli from usage spec -->
+# `mise system brew`
+
+- **Usage**: `mise system brew <SUBCOMMAND>`
+- **Source code**: [`src/cli/system/mod.rs`](https://github.com/jdx/mise/blob/main/src/cli/system/mod.rs)
+
+Manage Homebrew taps used by system packages
+
+These commands shell out to Homebrew and do not modify `mise.toml`. Use
+`[system.brew.taps]` when you want tap sources shared in config.
+
+## Subcommands
+
+- [`mise system brew tap [-n --dry-run] <TAP> [URL]`](/cli/system/brew/tap.md)
+- [`mise system brew untap [-n --dry-run] <TAPS>…`](/cli/system/brew/untap.md)

docs/cli/system/brew/tap.md

@@ -0,0 +1,30 @@
+<!-- @generated by usage-cli from usage spec -->
+# `mise system brew tap`
+
+- **Usage**: `mise system brew tap [-n --dry-run] <TAP> [URL]`
+- **Source code**: [`src/cli/system/brew/tap.rs`](https://github.com/jdx/mise/blob/main/src/cli/system/brew/tap.rs)
+
+Tap a Homebrew formula repository
+
+## Arguments
+
+### `<TAP>`
+
+Tap name, e.g. `owner/repo`
+
+### `[URL]`
+
+Git URL for non-GitHub or otherwise custom taps
+
+## Flags
+
+### `-n --dry-run`
+
+Print the command that would run without running it
+
+Examples:
+
+```
+mise system brew tap railwaycat/emacsmacport
+mise system brew tap acme/tools https://git.example.com/acme/homebrew-tools.git
+```

docs/cli/system/brew/untap.md

@@ -0,0 +1,26 @@
+<!-- @generated by usage-cli from usage spec -->
+# `mise system brew untap`
+
+- **Usage**: `mise system brew untap [-n --dry-run] <TAPS>…`
+- **Aliases**: `remove`, `rm`
+- **Source code**: [`src/cli/system/brew/untap.rs`](https://github.com/jdx/mise/blob/main/src/cli/system/brew/untap.rs)
+
+Untap Homebrew formula repositories
+
+## Arguments
+
+### `<TAPS>…`
+
+Tap name(s), e.g. `owner/repo`
+
+## Flags
+
+### `-n --dry-run`
+
+Print the command that would run without running it
+
+Examples:
+
+```
+mise system brew untap railwaycat/emacsmacport
+```

docs/system-packages/brew.md

@@ -1,6 +1,7 @@
 # brew <Badge type="warning" text="experimental" />
 
-Homebrew formulae — **without requiring Homebrew to be installed**.
+Homebrew formulae from `homebrew/core` — **without requiring Homebrew to be
+installed**.
 
 ```toml
 [system.packages]
@@ -17,7 +18,41 @@ prebuilt bottles from ghcr.io (verifying sha256 checksums), and performs the
 same relocation, code-signing, and linking work `brew` does when pouring a
 bottle. Formulae without a usable bottle are built from source, also without
 Homebrew (see [Source formulae](#source-formulae)). mise never shells out to
-`brew`.
+`brew` for homebrew/core formulae.
+
+Third-party taps are supported when Homebrew itself is installed. Tapped
+formulae are delegated to a real `brew` command; use the same
+fully-qualified formula name you would pass to `brew install`:
+
+```toml
+[system.packages]
+"brew:railwaycat/emacsmacport/emacs-mac" = "latest"
+```
+
+For non-GitHub taps, or taps whose URL cannot be inferred by Homebrew, add a
+tap source. This mirrors `[plugins]`: the key is the tap name and the value
+is the git URL.
+
+```toml
+[system.brew.taps]
+"acme/tools" = "https://git.example.com/acme/homebrew-tools.git"
+
+[system.packages]
+"brew:acme/tools/widget" = "latest"
+```
+
+Before installing or upgrading tapped formulae, mise runs `brew tap` for any
+configured tap URL and then `brew update-if-needed` so the tap is current.
+
+You can also manage taps imperatively, matching `mise plugins install` /
+`mise plugins uninstall`: these commands shell out to Homebrew and do not
+modify `mise.toml`.
+
+```sh
+mise system brew tap railwaycat/emacsmacport
+mise system brew tap acme/tools https://git.example.com/acme/homebrew-tools.git
+mise system brew untap acme/tools
+```
 
 This exists because shared-library packages — postgres, ffmpeg, imagemagick,
 php — fundamentally can't be served by mise's per-project backends like
@@ -131,8 +166,9 @@ operation.
 
 - **Formulae only.** Casks (GUI apps) and `brew services` are not
   implemented.
-- **No taps.** Third-party taps are Ruby code that requires Homebrew to
-  evaluate; only homebrew/core is supported.
+- **Tapped formulae require Homebrew.** mise's direct bottle/source installer
+  is only for homebrew/core. Fully-qualified third-party tap formulae are
+  delegated to a real `brew` command.
 - **Source builds cover the common formula shapes.** mise's formula shim
   implements the widely-used subset of the DSL (see
   [Source formulae](#source-formulae)); formulae that reach beyond it fail

man/man1/mise.1

@@ -463,6 +463,18 @@ Symlinks all ruby tool versions from an external tool into mise
 \fBsystem\fR
 [experimental] Manage system packages from `[system.packages]`, files
 .TP
+\fBsystem brew\fR
+Manage Homebrew taps used by system packages
+.TP
+\fBsystem brew tap\fR
+Tap a Homebrew formula repository
+.TP
+\fBsystem brew untap\fR
+Untap Homebrew formula repositories
+.RS
+\fIAliases: \fRremove, rm
+.RE
+.TP
 \fBsystem install\fR
 Install missing system packages from `[system.packages]`, apply files
 .RS
@@ -2777,6 +2789,39 @@ Symlinks all ruby tool versions from an external tool into mise
 .TP
 \fB\-\-brew\fR
 Get tool versions from Homebrew
+.SH "MISE SYSTEM BREW TAP"
+Tap a Homebrew formula repository
+.PP
+\fBUsage:\fR mise system brew tap [OPTIONS] <TAP> [<URL>]
+.PP
+\fBOptions:\fR
+.PP
+.TP
+\fB\-n, \-\-dry\-run\fR
+Print the command that would run without running it
+\fBArguments:\fR
+.PP
+.TP
+\fB<TAP>\fR
+Tap name, e.g. `owner/repo`
+.TP
+\fB<URL>\fR
+Git URL for non\-GitHub or otherwise custom taps
+.SH "MISE SYSTEM BREW UNTAP"
+Untap Homebrew formula repositories
+.PP
+\fBUsage:\fR mise system brew untap [OPTIONS] <TAPS> ...
+.PP
+\fBOptions:\fR
+.PP
+.TP
+\fB\-n, \-\-dry\-run\fR
+Print the command that would run without running it
+\fBArguments:\fR
+.PP
+.TP
+\fB<TAPS>\fR
+Tap name(s), e.g. `owner/repo`
 .SH "MISE SYSTEM INSTALL"
 Install missing system packages from `[system.packages]`, apply files
 from `[system.files]` and edits from `[system.edits]`, and write macOS

mise.usage.kdl

@@ -2897,6 +2897,37 @@ defaults are user preferences written with `defaults write`. Unlike
 ever acted on when explicitly requested with `mise system install` (or
 `mise bootstrap`).
 """#
+    cmd brew subcommand_required=#true help="Manage Homebrew taps used by system packages" {
+        long_help #"""
+Manage Homebrew taps used by system packages
+
+These commands shell out to Homebrew and do not modify `mise.toml`. Use
+`[system.brew.taps]` when you want tap sources shared in config.
+"""#
+        cmd tap help="Tap a Homebrew formula repository" {
+            after_long_help #"""
+Examples:
+
+    $ mise system brew tap railwaycat/emacsmacport
+    $ mise system brew tap acme/tools https://git.example.com/acme/homebrew-tools.git
+
+"""#
+            flag "-n --dry-run" help="Print the command that would run without running it"
+            arg <TAP> help="Tap name, e.g. `owner/repo`"
+            arg "[URL]" help="Git URL for non-GitHub or otherwise custom taps" required=#false
+        }
+        cmd untap help="Untap Homebrew formula repositories" {
+            alias remove rm
+            after_long_help #"""
+Examples:
+
+    $ mise system brew untap railwaycat/emacsmacport
+
+"""#
+            flag "-n --dry-run" help="Print the command that would run without running it"
+            arg <TAPS>… help="Tap name(s), e.g. `owner/repo`" var=#true
+        }
+    }
     cmd install help=#"""
 Install missing system packages from `[system.packages]`, apply files
 from `[system.files]` and edits from `[system.edits]`, and write macOS

src/cli/system/brew/mod.rs

@@ -0,0 +1,32 @@
+use clap::Subcommand;
+use eyre::Result;
+
+mod tap;
+mod untap;
+
+/// Manage Homebrew taps used by system packages
+///
+/// These commands shell out to Homebrew and do not modify `mise.toml`. Use
+/// `[system.brew.taps]` when you want tap sources shared in config.
+#[derive(Debug, clap::Args)]
+#[clap(verbatim_doc_comment)]
+pub struct SystemBrew {
+    #[clap(subcommand)]
+    command: Commands,
+}
+
+#[derive(Debug, Subcommand)]
+enum Commands {
+    Tap(tap::SystemBrewTap),
+    Untap(untap::SystemBrewUntap),
+}
+
+impl SystemBrew {
+    pub async fn run(self) -> Result<()> {
+        crate::config::Settings::get().ensure_experimental("mise system")?;
+        match self.command {
+            Commands::Tap(cmd) => cmd.run().await,
+            Commands::Untap(cmd) => cmd.run().await,
+        }
+    }
+}

src/cli/system/brew/tap.rs

@@ -0,0 +1,31 @@
+use eyre::Result;
+
+/// Tap a Homebrew formula repository
+#[derive(Debug, clap::Args)]
+#[clap(verbatim_doc_comment, after_long_help = AFTER_LONG_HELP)]
+pub struct SystemBrewTap {
+    /// Tap name, e.g. `owner/repo`
+    tap: String,
+
+    /// Git URL for non-GitHub or otherwise custom taps
+    #[clap(value_hint = clap::ValueHint::Url)]
+    url: Option<String>,
+
+    /// Print the command that would run without running it
+    #[clap(long, short = 'n')]
+    dry_run: bool,
+}
+
+impl SystemBrewTap {
+    pub async fn run(self) -> Result<()> {
+        crate::system::packages::brew::tap(&self.tap, self.url.as_deref(), self.dry_run).await
+    }
+}
+
+static AFTER_LONG_HELP: &str = color_print::cstr!(
+    r#"<bold><underline>Examples:</underline></bold>
+
+    $ <bold>mise system brew tap railwaycat/emacsmacport</bold>
+    $ <bold>mise system brew tap acme/tools https://git.example.com/acme/homebrew-tools.git</bold>
+"#
+);

src/cli/system/brew/untap.rs

@@ -0,0 +1,27 @@
+use eyre::Result;
+
+/// Untap Homebrew formula repositories
+#[derive(Debug, clap::Args)]
+#[clap(verbatim_doc_comment, visible_aliases = ["remove", "rm"], after_long_help = AFTER_LONG_HELP)]
+pub struct SystemBrewUntap {
+    /// Tap name(s), e.g. `owner/repo`
+    #[clap(required = true)]
+    taps: Vec<String>,
+
+    /// Print the command that would run without running it
+    #[clap(long, short = 'n')]
+    dry_run: bool,
+}
+
+impl SystemBrewUntap {
+    pub async fn run(self) -> Result<()> {
+        crate::system::packages::brew::untap(&self.taps, self.dry_run).await
+    }
+}
+
+static AFTER_LONG_HELP: &str = color_print::cstr!(
+    r#"<bold><underline>Examples:</underline></bold>
+
+    $ <bold>mise system brew untap railwaycat/emacsmacport</bold>
+"#
+);

src/cli/system/install.rs

@@ -62,7 +62,8 @@ impl SystemInstall {
             }
             system::packages_from_config(&config)
         } else {
-            system::packages_from_specs(&self.packages)?
+            let config = Config::get().await?;
+            system::packages_from_specs_with_config(&self.packages, Some(&config))?
         };
         // explicit packages or a --manager filter narrow the run to those
         // packages; files, edits, and defaults are part of the "apply

src/cli/system/mod.rs

@@ -1,6 +1,8 @@
 use clap::Subcommand;
 use eyre::Result;
 
+#[cfg(unix)]
+mod brew;
 pub(super) mod driver;
 pub(super) mod install;
 mod status;
@@ -30,6 +32,8 @@ pub struct System {
 
 #[derive(Debug, Subcommand)]
 enum Commands {
+    #[cfg(unix)]
+    Brew(brew::SystemBrew),
     Install(install::SystemInstall),
     Status(status::SystemStatus),
     Upgrade(upgrade::SystemUpgrade),
@@ -39,6 +43,8 @@ enum Commands {
 impl System {
     pub async fn run(self) -> Result<()> {
         match self.command {
+            #[cfg(unix)]
+            Commands::Brew(cmd) => cmd.run().await,
             Commands::Install(cmd) => cmd.run().await,
             Commands::Status(cmd) => cmd.run().await,
             Commands::Upgrade(cmd) => cmd.run().await,