refactor!: change Package API

This changes the following public APIs:

**(_breaking_) Events on the `Package` class**
The `uninstall:success` event on the `Package` class now receives an `InstallReceipt` as argument, instead of an
`InstallHandle`. This receipt is an in-memory representation of what was uninstalled. There's also a new
`uninstall:failed` event for situations where uninstallation for some
reason fails. Note: this also applies to the registry events (i.e.
`package:uninstall:success` and `package:uninstall:failed`).

---

**(_breaking_) `Package:uninstall()` is now asynchronous and receives two new arguments, similarly to `Package:install()`**
While package uninstallations remain synchronous under the hood, the public API has been changed from synchronous ->
asynchronous. Users of this method are recommended to provide a callback in situations where code needs to execute after
uninstallation fully completes.

---

**(_breaking_) `Package:get_install_path()` has been removed.

---

**`Package:install()` now takes an optional callback**
This callback allows consumers to be informed whether installation was successful or not without having to go through a
different, low-level, API. See below for a comparison between the old and new APIs:
```lua
-- before
local handle = pkg:install()
handle:once("closed", function ()
    -- ...
end)

-- after
pkg:install({}, function (success, result)
    -- ...
end)
```

20 files changed, 712 insertions, 421 deletions

diff --git a/lua/mason-core/functional/init.lua b/lua/mason-core/functional/init.lua
index d377d2db..7aa58940 100644
--- a/lua/mason-core/functional/init.lua
+++ b/lua/mason-core/functional/init.lua
@@ -3,9 +3,7 @@ local _ = {}
 local function lazy_require(module)
     return setmetatable({}, {
         __index = function(m, k)
-            return function(...)
-                return require(module)[k](...)
-            end
+            return require(module)[k]
         end,
     })
 end
diff --git a/lua/mason-core/installer/handle.lua b/lua/mason-core/installer/InstallHandle.lua
index 62da5bae..f5a42c53 100644
--- a/lua/mason-core/installer/handle.lua
+++ b/lua/mason-core/installer/InstallHandle.lua
@@ -43,10 +43,11 @@ function InstallHandleSpawnHandle:__tostring()
 end
 
 ---@class InstallHandle : EventEmitter
----@field package Package
+---@field package AbstractPackage
 ---@field state InstallHandleState
 ---@field stdio { buffers: { stdout: string[], stderr: string[] }, sink: StdioSink }
 ---@field is_terminated boolean
+---@field location InstallLocation
 ---@field private spawn_handles InstallHandleSpawnHandle[]
 local InstallHandle = {}
 InstallHandle.__index = InstallHandle
@@ -70,14 +71,17 @@ local function new_sink(handle)
     }
 end
 
----@param pkg Package
-function InstallHandle:new(pkg)
+---@param pkg AbstractPackage
+---@param location InstallLocation
+function InstallHandle:new(pkg, location)
+    ---@type InstallHandle
     local instance = EventEmitter.new(self)
     instance.state = "IDLE"
     instance.package = pkg
     instance.spawn_handles = {}
     instance.stdio = new_sink(instance)
     instance.is_terminated = false
+    instance.location = location
     return instance
 end
 
diff --git a/lua/mason-core/installer/location.lua b/lua/mason-core/installer/InstallLocation.lua
index 9cdf097f..00b517b9 100644
--- a/lua/mason-core/installer/location.lua
+++ b/lua/mason-core/installer/InstallLocation.lua
@@ -59,9 +59,9 @@ function InstallLocation:opt(path)
     return Path.concat { self.dir, "opt", path }
 end
 
----@param path string?
-function InstallLocation:package(path)
-    return Path.concat { self.dir, "packages", path }
+---@param pkg string?
+function InstallLocation:package(pkg)
+    return Path.concat { self.dir, "packages", pkg }
 end
 
 ---@param path string?
@@ -79,6 +79,11 @@ function InstallLocation:registry(path)
     return Path.concat { self.dir, "registries", path }
 end
 
+---@param pkg string
+function InstallLocation:receipt(pkg)
+    return Path.concat { self:package(pkg), "mason-receipt.json" }
+end
+
 ---@param opts { PATH: '"append"' | '"prepend"' | '"skip"' }
 function InstallLocation:set_env(opts)
     vim.env.MASON = self.dir
diff --git a/lua/mason-core/installer/runner.lua b/lua/mason-core/installer/InstallRunner.lua
index 64aa605d..fa2b3fcf 100644
--- a/lua/mason-core/installer/runner.lua
+++ b/lua/mason-core/installer/InstallRunner.lua
@@ -2,41 +2,45 @@ local Result = require "mason-core.result"
 local _ = require "mason-core.functional"
 local a = require "mason-core.async"
 local compiler = require "mason-core.installer.compiler"
+local control = require "mason-core.async.control"
 local fs = require "mason-core.fs"
 local linker = require "mason-core.installer.linker"
 local log = require "mason-core.log"
 local registry = require "mason-registry"
 
+local OneShotChannel = control.OneShotChannel
+
 local InstallContext = require "mason-core.installer.context"
 
 ---@class InstallRunner
----@field location InstallLocation
 ---@field handle InstallHandle
----@field semaphore Semaphore
----@field permit Permit?
+---@field global_semaphore Semaphore
+---@field global_permit Permit?
+---@field package_permit Permit?
 local InstallRunner = {}
 InstallRunner.__index = InstallRunner
 
----@param location InstallLocation
 ---@param handle InstallHandle
 ---@param semaphore Semaphore
-function InstallRunner:new(location, handle, semaphore)
+function InstallRunner:new(handle, semaphore)
     ---@type InstallRunner
     local instance = {}
     setmetatable(instance, self)
     instance.location = location
-    instance.semaphore = semaphore
+    instance.global_semaphore = semaphore
     instance.handle = handle
     return instance
 end
 
+---@alias InstallRunnerCallback fun(success: true, receipt: InstallReceipt) | fun(success: false, handle: InstallHandle, error: any)
+
 ---@param opts PackageInstallOpts
----@param callback? fun(success: boolean, result: any)
+---@param callback? InstallRunnerCallback
 function InstallRunner:execute(opts, callback)
     local handle = self.handle
     log.fmt_info("Executing installer for %s %s", handle.package, opts)
 
-    local context = InstallContext:new(handle, self.location, opts)
+    local context = InstallContext:new(handle, opts)
 
     local tailed_output = {}
 
@@ -79,25 +83,27 @@ function InstallRunner:execute(opts, callback)
         self:release_lock()
         self:release_permit()
 
-        if callback then
-            callback(success, result)
-        end
-
         if success then
             log.fmt_info("Installation succeeded for %s", handle.package)
-            handle.package:emit("install:success", handle)
-            registry:emit("package:install:success", handle.package, handle)
+            if callback then
+                callback(true, result.receipt)
+            end
+            handle.package:emit("install:success", result.receipt)
+            registry:emit("package:install:success", handle.package, result.receipt)
         else
             log.fmt_error("Installation failed for %s error=%s", handle.package, result)
-            handle.package:emit("install:failed", handle, result)
-            registry:emit("package:install:failed", handle.package, handle, result)
+            if callback then
+                callback(false, result)
+            end
+            handle.package:emit("install:failed", result)
+            registry:emit("package:install:failed", handle.package, result)
         end
     end)
 
     local cancel_execution = a.run(function()
         return Result.try(function(try)
-            try(self:acquire_permit())
-            try(self.location:initialize())
+            try(self.handle.location:initialize())
+            try(self:acquire_permit()):receive()
             try(self:acquire_lock(opts.force))
 
             context.receipt:with_start_time(vim.loop.gettimeofday())
@@ -107,7 +113,7 @@ function InstallRunner:execute(opts, callback)
 
             -- 2. run installer
             ---@type async fun(ctx: InstallContext): Result
-            local installer = try(compiler.compile(handle.package.spec, opts))
+            local installer = try(compiler.compile_installer(handle.package.spec, opts))
             try(context:execute(installer))
 
             -- 3. promote temporary installation dir
@@ -116,28 +122,23 @@ function InstallRunner:execute(opts, callback)
             end))
 
             -- 4. link package & write receipt
-            return linker
-                .link(context)
-                :and_then(function()
-                    return context:build_receipt(context)
-                end)
-                :and_then(
+            try(linker.link(context):on_failure(function()
+                -- unlink any links that were made before failure
+                context:build_receipt():on_success(
                     ---@param receipt InstallReceipt
                     function(receipt)
-                        return receipt:write(context.cwd:get())
+                        linker.unlink(handle.package, receipt, self.handle.location):on_failure(function(err)
+                            log.error("Failed to unlink failed installation.", err)
+                        end)
                     end
                 )
-                :on_failure(function()
-                    -- unlink any links that were made before failure
-                    context:build_receipt():on_success(
-                        ---@param receipt InstallReceipt
-                        function(receipt)
-                            linker.unlink(handle.package, receipt, self.location):on_failure(function(err)
-                                log.error("Failed to unlink failed installation.", err)
-                            end)
-                        end
-                    )
-                end)
+            end))
+            ---@type InstallReceipt
+            local receipt = try(context:build_receipt())
+            try(Result.pcall(fs.sync.write_file, handle.location:receipt(handle.package.name), receipt:to_json()))
+            return {
+                receipt = receipt,
+            }
         end):get_or_throw()
     end, finalize)
 
@@ -157,7 +158,7 @@ end
 ---@async
 ---@private
 function InstallRunner:release_lock()
-    pcall(fs.async.unlink, self.location:lockfile(self.handle.package.name))
+    pcall(fs.async.unlink, self.handle.location:lockfile(self.handle.package.name))
 end
 
 ---@async
@@ -166,7 +167,7 @@ end
 function InstallRunner:acquire_lock(force)
     local pkg = self.handle.package
     log.debug("Attempting to lock package", pkg)
-    local lockfile = self.location:lockfile(pkg.name)
+    local lockfile = self.handle.location:lockfile(pkg.name)
     if force ~= true and fs.async.file_exists(lockfile) then
         log.error("Lockfile already exists.", pkg)
         return Result.failure(
@@ -181,33 +182,45 @@ function InstallRunner:acquire_lock(force)
     return Result.success(lockfile)
 end
 
----@async
 ---@private
 function InstallRunner:acquire_permit()
+    local channel = OneShotChannel:new()
+    log.fmt_debug("Acquiring permit for %s", self.handle.package)
     local handle = self.handle
-    if handle:is_active() or handle:is_closed() then
-        log.fmt_debug("Received active or closed handle %s", handle)
+    if handle:is_active() or handle:is_closing() then
+        log.fmt_debug("Received active or closing handle %s", handle)
         return Result.failure "Invalid handle state."
     end
 
     handle:queued()
-    local permit = self.semaphore:acquire()
-    if handle:is_closed() then
-        permit:forget()
-        log.fmt_trace("Installation was aborted %s", handle)
-        return Result.failure "Installation was aborted."
-    end
-    log.fmt_trace("Activating handle %s", handle)
-    handle:active()
-    self.permit = permit
-    return Result.success()
+    a.run(function()
+        self.global_permit = self.global_semaphore:acquire()
+        self.package_permit = handle.package:acquire_permit()
+    end, function(success, err)
+        if not success or handle:is_closing() then
+            if not success then
+                log.error("Acquiring permits failed", err)
+            end
+            self:release_permit()
+        else
+            log.fmt_debug("Activating handle %s", handle)
+            handle:active()
+            channel:send()
+        end
+    end)
+
+    return Result.success(channel)
 end
 
 ---@private
 function InstallRunner:release_permit()
-    if self.permit then
-        self.permit:forget()
-        self.permit = nil
+    if self.global_permit then
+        self.global_permit:forget()
+        self.global_permit = nil
+    end
+    if self.package_permit then
+        self.package_permit:forget()
+        self.package_permit = nil
     end
 end
 
diff --git a/lua/mason-core/installer/UninstallRunner.lua b/lua/mason-core/installer/UninstallRunner.lua
new file mode 100644
index 00000000..661bfefa
--- /dev/null
+++ b/lua/mason-core/installer/UninstallRunner.lua
@@ -0,0 +1,119 @@
+local InstallContext = require "mason-core.installer.context"
+local Result = require "mason-core.result"
+local _ = require "mason-core.functional"
+local a = require "mason-core.async"
+local compiler = require "mason-core.installer.compiler"
+local control = require "mason-core.async.control"
+local fs = require "mason-core.fs"
+local log = require "mason-core.log"
+local registry = require "mason-registry"
+
+local OneShotChannel = control.OneShotChannel
+
+---@class UninstallRunner
+---@field handle InstallHandle
+---@field global_semaphore Semaphore
+---@field package_permit Permit?
+---@field global_permit Permit?
+local UninstallRunner = {}
+UninstallRunner.__index = UninstallRunner
+
+---@param handle InstallHandle
+---@param global_semaphore Semaphore
+---@return UninstallRunner
+function UninstallRunner:new(handle, global_semaphore)
+    local instance = {}
+    setmetatable(instance, self)
+    instance.handle = handle
+    instance.global_semaphore = global_semaphore
+    return instance
+end
+
+---@param opts PackageUninstallOpts
+---@param callback? InstallRunnerCallback
+function UninstallRunner:execute(opts, callback)
+    local pkg = self.handle.package
+    local location = self.handle.location
+    log.fmt_info("Executing uninstaller for %s %s", pkg, opts)
+    a.run(function()
+        Result.try(function(try)
+            if not opts.bypass_permit then
+                try(self:acquire_permit()):receive()
+            end
+            ---@type InstallReceipt?
+            local receipt = pkg:get_receipt(location):or_else(nil)
+            if receipt == nil then
+                log.fmt_warn("Receipt not found when uninstalling %s", pkg)
+            end
+            try(pkg:unlink(location))
+            fs.sync.rmrf(location:package(pkg.name))
+            return receipt
+        end):get_or_throw()
+    end, function(success, result)
+        if not self.handle:is_closing() then
+            self.handle:close()
+        end
+        self:release_permit()
+
+        if success then
+            local receipt = result
+            log.fmt_info("Uninstallation succeeded for %s", pkg)
+            if callback then
+                callback(true, receipt)
+            end
+            pkg:emit("uninstall:success", receipt)
+            registry:emit("package:uninstall:success", pkg, receipt)
+        else
+            log.fmt_error("Uninstallation failed for %s error=%s", pkg, result)
+            if callback then
+                callback(false, result)
+            end
+            pkg:emit("uninstall:failed", result)
+            registry:emit("package:uninstall:failed", pkg, result)
+        end
+    end)
+end
+
+---@private
+function UninstallRunner:acquire_permit()
+    local channel = OneShotChannel:new()
+    log.fmt_debug("Acquiring permit for %s", self.handle.package)
+    local handle = self.handle
+    if handle:is_active() or handle:is_closing() then
+        log.fmt_debug("Received active or closing handle %s", handle)
+        return Result.failure "Invalid handle state."
+    end
+
+    handle:queued()
+    a.run(function()
+        self.global_permit = self.global_semaphore:acquire()
+        self.package_permit = handle.package:acquire_permit()
+    end, function(success, err)
+        if not success or handle:is_closing() then
+            if not success then
+                log.error("Acquiring permits failed", err)
+            end
+            self:release_permit()
+        else
+            log.fmt_debug("Activating handle %s", handle)
+            handle:active()
+            channel:send()
+        end
+    end)
+
+    return Result.success(channel)
+end
+
+---@private
+function UninstallRunner:release_permit()
+    if self.global_permit then
+        self.global_permit:forget()
+        self.global_permit = nil
+    end
+    if self.package_permit then
+        self.package_permit:forget()
+        self.package_permit = nil
+    end
+end
+
+return UninstallRunner
diff --git a/lua/mason-core/installer/compiler/compilers/github/init.lua b/lua/mason-core/installer/compiler/compilers/github/init.lua
index d8646975..5a8dfce5 100644
--- a/lua/mason-core/installer/compiler/compilers/github/init.lua
+++ b/lua/mason-core/installer/compiler/compilers/github/init.lua
@@ -20,7 +20,7 @@ end
 ---@async
 ---@param ctx InstallContext
 ---@param source ParsedGitHubReleaseSource | ParsedGitHubBuildSource
-function M.install(ctx, source, purl)
+function M.install(ctx, source)
     if source.asset then
         source = source--[[@as ParsedGitHubReleaseSource]]
         return require("mason-core.installer.compiler.compilers.github.release").install(ctx, source)
diff --git a/lua/mason-core/installer/compiler/init.lua b/lua/mason-core/installer/compiler/init.lua
index e1df6784..4eed986b 100644
--- a/lua/mason-core/installer/compiler/init.lua
+++ b/lua/mason-core/installer/compiler/init.lua
@@ -71,9 +71,9 @@ local function upsert(dst, src)
 end
 
 ---@param source RegistryPackageSource
----@param version string
+---@param version string?
 local function coalesce_source(source, version)
-    if source.version_overrides then
+    if version and source.version_overrides then
         for i = #source.version_overrides, 1, -1 do
             local version_override = source.version_overrides[i]
             local version_type, constraint = unpack(_.split(":", version_override.constraint))
@@ -94,18 +94,12 @@ local function coalesce_source(source, version)
                 end):get_or_else(false)
 
                 if version_match then
-                    if version_override.id then
-                        -- Because this entry provides its own purl id, it overrides the entire source definition.
-                        return version_override
-                    else
-                        -- Upsert the default source with the contents of the version override.
-                        return upsert(vim.deepcopy(source), _.dissoc("constraint", version_override))
-                    end
+                    return _.dissoc("constraint", version_override)
                 end
             end
         end
     end
-    return source
+    return _.dissoc("version_overrides", source)
 end
 
 ---@param spec RegistryPackageSpec
@@ -121,7 +115,7 @@ function M.parse(spec, opts)
             )
         end
 
-        local source = opts.version and coalesce_source(spec.source, opts.version) or spec.source
+        local source = coalesce_source(spec.source, opts.version)
 
         ---@type Purl
         local purl = try(Purl.parse(source.id))
@@ -149,7 +143,7 @@ end
 ---@async
 ---@param spec RegistryPackageSpec
 ---@param opts PackageInstallOpts
-function M.compile(spec, opts)
+function M.compile_installer(spec, opts)
     log.debug("Compiling installer.", spec.name, opts)
     return Result.try(function(try)
         -- Parsers run synchronously and may access API functions, so we schedule before-hand.
@@ -210,9 +204,10 @@ function M.compile(spec, opts)
                 ctx.receipt:with_source {
                     type = ctx.package.spec.schema,
                     id = Purl.compile(parsed.purl),
+                    -- Exclude the "install" field from "mason" sources because this is a Lua function.
+                    raw = parsed.purl.type == "mason" and _.dissoc("install", parsed.raw_source) or parsed.raw_source,
                 }
-            end):on_failure(function(err)
-                error(err, 0)
+                ctx.receipt:with_install_options(opts)
             end)
         end
     end)
diff --git a/lua/mason-core/installer/compiler/link.lua b/lua/mason-core/installer/compiler/link.lua
index 9719eaa9..d60fce47 100644
--- a/lua/mason-core/installer/compiler/link.lua
+++ b/lua/mason-core/installer/compiler/link.lua
@@ -38,7 +38,7 @@ local bin_delegates = {
             local python = platform.is.win and "python" or "python3"
             return ctx:write_shell_exec_wrapper(
                 bin,
-                ("%s %q"):format(python, path.concat { ctx.package:get_install_path(), target })
+                ("%s %q"):format(python, path.concat { ctx:get_install_path(), target })
             )
         end)
     end,
@@ -66,7 +66,7 @@ local bin_delegates = {
             return ctx:write_shell_exec_wrapper(
                 bin,
                 ("dotnet %q"):format(path.concat {
-                    ctx.package:get_install_path(),
+                    ctx:get_install_path(),
                     target,
                 })
             )
@@ -103,7 +103,7 @@ local bin_delegates = {
             return ctx:write_shell_exec_wrapper(
                 bin,
                 ("java -jar %q"):format(path.concat {
-                    ctx.package:get_install_path(),
+                    ctx:get_install_path(),
                     target,
                 })
             )
diff --git a/lua/mason-core/installer/context/cwd.lua b/lua/mason-core/installer/context/InstallContextCwd.lua
index 2b74bf55..b365cbd9 100644
--- a/lua/mason-core/installer/context/cwd.lua
+++ b/lua/mason-core/installer/context/InstallContextCwd.lua
@@ -3,20 +3,16 @@ local fs = require "mason-core.fs"
 local path = require "mason-core.path"
 
 ---@class InstallContextCwd
----@field private location InstallLocation Defines the upper boundary for which paths are allowed as cwd.
 ---@field private handle InstallHandle
 ---@field private cwd string?
 local InstallContextCwd = {}
 InstallContextCwd.__index = InstallContextCwd
 
 ---@param handle InstallHandle
----@param location InstallLocation
-function InstallContextCwd:new(handle, location)
-    assert(location, "location not provided")
+function InstallContextCwd:new(handle)
     ---@type InstallContextCwd
     local instance = {}
     setmetatable(instance, self)
-    instance.location = location
     instance.handle = handle
     instance.cwd = nil
     return instance
@@ -24,7 +20,7 @@ end
 
 function InstallContextCwd:initialize()
     return Result.try(function(try)
-        local staging_dir = self.location:staging(self.handle.package.name)
+        local staging_dir = self.handle.location:staging(self.handle.package.name)
         if fs.sync.dir_exists(staging_dir) then
             try(Result.pcall(fs.sync.rmrf, staging_dir))
         end
@@ -42,8 +38,8 @@ end
 function InstallContextCwd:set(new_abs_cwd)
     assert(type(new_abs_cwd) == "string", "new_cwd is not a string")
     assert(
-        path.is_subdirectory(self.location:get_dir(), new_abs_cwd),
-        ("%q is not a subdirectory of %q"):format(new_abs_cwd, self.location)
+        path.is_subdirectory(self.handle.location:get_dir(), new_abs_cwd),
+        ("%q is not a subdirectory of %q"):format(new_abs_cwd, self.handle.location)
     )
     self.cwd = new_abs_cwd
     return self
diff --git a/lua/mason-core/installer/context/fs.lua b/lua/mason-core/installer/context/InstallContextFs.lua
index 93379017..93379017 100644
--- a/lua/mason-core/installer/context/fs.lua
+++ b/lua/mason-core/installer/context/InstallContextFs.lua
diff --git a/lua/mason-core/installer/context/spawn.lua b/lua/mason-core/installer/context/InstallContextSpawn.lua
index f2ce8df2..f2ce8df2 100644
--- a/lua/mason-core/installer/context/spawn.lua
+++ b/lua/mason-core/installer/context/InstallContextSpawn.lua
diff --git a/lua/mason-core/installer/context/init.lua b/lua/mason-core/installer/context/init.lua
index 425bf39c..097ea696 100644
--- a/lua/mason-core/installer/context/init.lua
+++ b/lua/mason-core/installer/context/init.lua
@@ -1,8 +1,9 @@
-local InstallContextCwd = require "mason-core.installer.context.cwd"
-local InstallContextFs = require "mason-core.installer.context.fs"
-local InstallContextSpawn = require "mason-core.installer.context.spawn"
+local InstallContextCwd = require "mason-core.installer.context.InstallContextCwd"
+local InstallContextFs = require "mason-core.installer.context.InstallContextFs"
+local InstallContextSpawn = require "mason-core.installer.context.InstallContextSpawn"
 local Result = require "mason-core.result"
 local _ = require "mason-core.functional"
+local a = require "mason-core.async"
 local fs = require "mason-core.fs"
 local log = require "mason-core.log"
 local path = require "mason-core.path"
@@ -15,7 +16,7 @@ local receipt = require "mason-core.receipt"
 ---@field location InstallLocation
 ---@field spawn InstallContextSpawn
 ---@field handle InstallHandle
----@field package Package
+---@field package AbstractPackage
 ---@field cwd InstallContextCwd
 ---@field opts PackageInstallOpts
 ---@field stdio_sink StdioSink
@@ -24,17 +25,16 @@ local InstallContext = {}
 InstallContext.__index = InstallContext
 
 ---@param handle InstallHandle
----@param location InstallLocation
 ---@param opts PackageInstallOpts
-function InstallContext:new(handle, location, opts)
-    local cwd = InstallContextCwd:new(handle, location)
+function InstallContext:new(handle, opts)
+    local cwd = InstallContextCwd:new(handle)
     local spawn = InstallContextSpawn:new(handle, cwd, false)
     local fs = InstallContextFs:new(cwd)
     return setmetatable({
         cwd = cwd,
         spawn = spawn,
         handle = handle,
-        location = location,
+        location = handle.location, -- for convenience
         package = handle.package, -- for convenience
         fs = fs,
         receipt = receipt.InstallReceiptBuilder:new(),
@@ -51,23 +51,35 @@ end
 ---@async
 function InstallContext:promote_cwd()
     local cwd = self.cwd:get()
-    local install_path = self.package:get_install_path()
+    local install_path = self:get_install_path()
     if install_path == cwd then
-        log.fmt_debug("cwd %s is already promoted (at %s)", cwd, install_path)
+        log.fmt_debug("cwd %s is already promoted", cwd)
         return
     end
     log.fmt_debug("Promoting cwd %s to %s", cwd, install_path)
+
     -- 1. Uninstall any existing installation
-    self.handle.package:uninstall()
+    if self.handle.package:is_installed() then
+        a.wait(function(resolve, reject)
+            self.handle.package:uninstall({ bypass_permit = true }, function(success, result)
+                if not success then
+                    reject(result)
+                else
+                    resolve()
+                end
+            end)
+        end)
+    end
+
     -- 2. Prepare for renaming cwd to destination
     if platform.is.unix then
         -- Some Unix systems will raise an error when renaming a directory to a destination that does not already exist.
         fs.async.mkdir(install_path)
     end
-    -- 3. Move the cwd to the final installation directory
-    fs.async.rename(cwd, install_path)
-    -- 4. Update cwd
+    -- 3. Update cwd
     self.cwd:set(install_path)
+    -- 4. Move the cwd to the final installation directory
+    fs.async.rename(cwd, install_path)
 end
 
 ---@param rel_path string The relative path from the current working directory to change cwd to. Will only restore to the initial cwd after execution of fn (if provided).
@@ -94,7 +106,7 @@ function InstallContext:write_node_exec_wrapper(new_executable_rel_path, script_
     return self:write_shell_exec_wrapper(
         new_executable_rel_path,
         ("node %q"):format(path.concat {
-            self.package:get_install_path(),
+            self:get_install_path(),
             script_rel_path,
         })
     )
@@ -109,7 +121,7 @@ function InstallContext:write_ruby_exec_wrapper(new_executable_rel_path, script_
     return self:write_shell_exec_wrapper(
         new_executable_rel_path,
         ("ruby %q"):format(path.concat {
-            self.package:get_install_path(),
+            self:get_install_path(),
             script_rel_path,
         })
     )
@@ -124,7 +136,7 @@ function InstallContext:write_php_exec_wrapper(new_executable_rel_path, script_r
     return self:write_shell_exec_wrapper(
         new_executable_rel_path,
         ("php %q"):format(path.concat {
-            self.package:get_install_path(),
+            self:get_install_path(),
             script_rel_path,
         })
     )
@@ -149,7 +161,7 @@ function InstallContext:write_pyvenv_exec_wrapper(new_executable_rel_path, modul
         new_executable_rel_path,
         ("%q -m %s"):format(
             path.concat {
-                pypi.venv_path(self.package:get_install_path()),
+                pypi.venv_path(self:get_install_path()),
                 "python",
             },
             module
@@ -169,7 +181,7 @@ function InstallContext:write_exec_wrapper(new_executable_rel_path, target_execu
     return self:write_shell_exec_wrapper(
         new_executable_rel_path,
         ("%q"):format(path.concat {
-            self.package:get_install_path(),
+            self:get_install_path(),
             target_executable_rel_path,
         })
     )
@@ -264,4 +276,8 @@ function InstallContext:build_receipt()
     end)
 end
 
+function InstallContext:get_install_path()
+    return self.location:package(self.package.name)
+end
+
 return InstallContext
diff --git a/lua/mason-core/installer/linker.lua b/lua/mason-core/installer/linker.lua
index a5c54273..a26d2592 100644
--- a/lua/mason-core/installer/linker.lua
+++ b/lua/mason-core/installer/linker.lua
@@ -57,7 +57,7 @@ local function unlink(receipt, link_context, location)
     end)
 end
 
----@param pkg Package
+---@param pkg AbstractPackage
 ---@param receipt InstallReceipt
 ---@param location InstallLocation
 ---@nodiscard
@@ -82,31 +82,27 @@ local function link(context, link_context, link_fn)
                 name = ("%s.cmd"):format(name)
             end
             local new_abs_path = link_context.prefix(name, context.location)
-            local target_abs_path = path.concat { context.package:get_install_path(), rel_path }
+            local target_abs_path = path.concat { context:get_install_path(), rel_path }
             local target_rel_path = path.relative(new_abs_path, target_abs_path)
 
-            do
-                -- 1. Ensure destination directory exists
-                a.scheduler()
-                local dir = vim.fn.fnamemodify(new_abs_path, ":h")
-                if not fs.async.dir_exists(dir) then
-                    try(Result.pcall(fs.async.mkdirp, dir))
-                end
+            -- 1. Ensure destination directory exists
+            a.scheduler()
+            local dir = vim.fn.fnamemodify(new_abs_path, ":h")
+            if not fs.async.dir_exists(dir) then
+                try(Result.pcall(fs.async.mkdirp, dir))
             end
 
-            do
-                -- 2. Ensure source file exists and target doesn't yet exist OR if --force unlink target if it already
-                -- exists.
-                if context.opts.force then
-                    if fs.async.file_exists(new_abs_path) then
-                        try(Result.pcall(fs.async.unlink, new_abs_path))
-                    end
-                elseif fs.async.file_exists(new_abs_path) then
-                    return Result.failure(("%q is already linked."):format(new_abs_path, name))
-                end
-                if not fs.async.file_exists(target_abs_path) then
-                    return Result.failure(("Link target %q does not exist."):format(target_abs_path))
+            -- 2. Ensure source file exists and target doesn't yet exist OR if --force unlink target if it already
+            -- exists.
+            if context.opts.force then
+                if fs.async.file_exists(new_abs_path) then
+                    try(Result.pcall(fs.async.unlink, new_abs_path))
                 end
+            elseif fs.async.file_exists(new_abs_path) then
+                return Result.failure(("%q is already linked."):format(new_abs_path, name))
+            end
+            if not fs.async.file_exists(target_abs_path) then
+                return Result.failure(("Link target %q does not exist."):format(target_abs_path))
             end
 
             -- 3. Execute link.
diff --git a/lua/mason-core/installer/managers/gem.lua b/lua/mason-core/installer/managers/gem.lua
index cb502de5..e8723d7e 100644
--- a/lua/mason-core/installer/managers/gem.lua
+++ b/lua/mason-core/installer/managers/gem.lua
@@ -54,14 +54,14 @@ function M.create_bin_wrapper(bin)
         ctx.write_shell_exec_wrapper,
         ctx,
         bin,
-        path.concat { ctx.package:get_install_path(), bin_path },
+        path.concat { ctx:get_install_path(), bin_path },
         {
             GEM_PATH = platform.when {
                 unix = function()
-                    return ("%s:$GEM_PATH"):format(ctx.package:get_install_path())
+                    return ("%s:$GEM_PATH"):format(ctx:get_install_path())
                 end,
                 win = function()
-                    return ("%s;%%GEM_PATH%%"):format(ctx.package:get_install_path())
+                    return ("%s;%%GEM_PATH%%"):format(ctx:get_install_path())
                 end,
             },
         }
diff --git a/lua/mason-core/installer/managers/npm.lua b/lua/mason-core/installer/managers/npm.lua
index 10a3e9fd..df8ece35 100644
--- a/lua/mason-core/installer/managers/npm.lua
+++ b/lua/mason-core/installer/managers/npm.lua
@@ -70,6 +70,14 @@ function M.install(pkg, version, opts)
     }
 end
 
+---@async
+---@param pkg string
+function M.uninstall(pkg)
+    local ctx = installer.context()
+    ctx.stdio_sink.stdout(("Uninstalling npm package %s…\n"):format(pkg))
+    return ctx.spawn.npm { "uninstall", pkg }
+end
+
 ---@param exec string
 function M.bin_path(exec)
     return Result.pcall(platform.when, {
diff --git a/lua/mason-core/installer/managers/pypi.lua b/lua/mason-core/installer/managers/pypi.lua
index c569e0fd..85fadc9f 100644
--- a/lua/mason-core/installer/managers/pypi.lua
+++ b/lua/mason-core/installer/managers/pypi.lua
@@ -214,6 +214,19 @@ function M.install(pkg, version, opts)
     }, opts.install_extra_args)
 end
 
+---@async
+---@param pkg string
+function M.uninstall(pkg)
+    log.fmt_debug("pypi: uninstall %s", pkg)
+    return venv_python {
+        "-m",
+        "pip",
+        "uninstall",
+        "-y",
+        pkg,
+    }
+end
+
 ---@param executable string
 function M.bin_path(executable)
     local ctx = installer.context()
diff --git a/lua/mason-core/package.lua b/lua/mason-core/package.lua
deleted file mode 100644
index a8a7ac79..00000000
--- a/lua/mason-core/package.lua
+++ /dev/null
@@ -1,274 +0,0 @@
-local EventEmitter = require "mason-core.EventEmitter"
-local InstallLocation = require "mason-core.installer.location"
-local InstallRunner = require "mason-core.installer.runner"
-local Optional = require "mason-core.optional"
-local Purl = require "mason-core.purl"
-local Result = require "mason-core.result"
-local _ = require "mason-core.functional"
-local fs = require "mason-core.fs"
-local log = require "mason-core.log"
-local path = require "mason-core.path"
-local platform = require "mason-core.platform"
-local registry = require "mason-registry"
-local settings = require "mason.settings"
-local Semaphore = require("mason-core.async.control").Semaphore
-
----@class Package : EventEmitter
----@field name string
----@field spec RegistryPackageSpec
----@field private handle InstallHandle The currently associated handle.
-local Package = {}
-Package.__index = Package
-setmetatable(Package, { __index = EventEmitter })
-
----@param package_identifier string
----@return string, string?
-Package.Parse = function(package_identifier)
-    local name, version = unpack(vim.split(package_identifier, "@"))
-    return name, version
-end
-
----@alias PackageLanguage string
-
----@type table<PackageLanguage, PackageLanguage>
-Package.Lang = setmetatable({}, {
-    __index = function(s, lang)
-        s[lang] = lang
-        return s[lang]
-    end,
-})
-
----@enum PackageCategory
-Package.Cat = {
-    Compiler = "Compiler",
-    Runtime = "Runtime",
-    DAP = "DAP",
-    LSP = "LSP",
-    Linter = "Linter",
-    Formatter = "Formatter",
-}
-
----@alias PackageLicense string
-
----@type table<PackageLicense, PackageLicense>
-Package.License = setmetatable({}, {
-    __index = function(s, license)
-        s[license] = license
-        return s[license]
-    end,
-})
-
----@class RegistryPackageSourceVersionOverride : RegistryPackageSource
----@field constraint string
-
----@class RegistryPackageSource
----@field id string PURL-compliant identifier.
----@field version_overrides? RegistryPackageSourceVersionOverride[]
-
----@class RegistryPackageSchemas
----@field lsp string?
-
----@class RegistryPackageDeprecation
----@field since string
----@field message string
-
----@alias RegistryPackageSpecSchema
---- | '"registry+v1"'
-
----@class RegistryPackageSpec
----@field schema RegistryPackageSpecSchema
----@field name string
----@field description string
----@field homepage string
----@field licenses string[]
----@field languages string[]
----@field categories string[]
----@field source RegistryPackageSource
----@field deprecation RegistryPackageDeprecation?
----@field schemas RegistryPackageSchemas?
----@field bin table<string, string>?
----@field share table<string, string>?
----@field opt table<string, string>?
-
----@param spec RegistryPackageSpec
-local function validate_spec(spec)
-    if platform.cached_features["nvim-0.11"] ~= 1 then
-        return
-    end
-    vim.validate("schema", spec.schema, _.equals "registry+v1", "registry+v1")
-    vim.validate("name", spec.name, "string")
-    vim.validate("description", spec.description, "string")
-    vim.validate("homepage", spec.homepage, "string")
-    vim.validate("licenses", spec.licenses, "table")
-    vim.validate("categories", spec.categories, "table")
-    vim.validate("languages", spec.languages, "table")
-    vim.validate("source", spec.source, "table")
-    vim.validate("bin", spec.bin, { "table", "nil" })
-    vim.validate("share", spec.share, { "table", "nil" })
-end
-
----@param spec RegistryPackageSpec
-function Package:new(spec)
-    validate_spec(spec)
-    local instance = EventEmitter.new(self) --[[@as Package]]
-    instance.name = spec.name -- for convenient access
-    instance.spec = spec
-    return instance
-end
-
-function Package:new_handle()
-    self:get_handle():if_present(function(handle)
-        assert(handle:is_closed(), "Cannot create new handle because existing handle is not closed.")
-    end)
-    log.fmt_trace("Creating new handle for %s", self)
-    local InstallationHandle = require "mason-core.installer.handle"
-    local handle = InstallationHandle:new(self)
-    self.handle = handle
-
-    -- Ideally we'd decouple this and leverage Mason's event system, but to allow loading as little as possible during
-    -- setup (i.e. not load modules related to Mason's event system) of the mason.nvim plugin we explicitly call into
-    -- terminator here.
-    require("mason-core.terminator").register(handle)
-
-    self:emit("handle", handle)
-    registry:emit("package:handle", self, handle)
-
-    return handle
-end
-
----@alias PackageInstallOpts { version?: string, debug?: boolean, target?: string, force?: boolean, strict?: boolean }
-
--- TODO this needs to be elsewhere
-local semaphore = Semaphore:new(settings.current.max_concurrent_installers)
-
-function Package:is_installing()
-    return self:get_handle()
-        :map(
-            ---@param handle InstallHandle
-            function(handle)
-                return not handle:is_closed()
-            end
-        )
-        :or_else(false)
-end
-
----@param opts? PackageInstallOpts
----@param callback? fun(success: boolean, result: any)
----@return InstallHandle
-function Package:install(opts, callback)
-    opts = opts or {}
-    assert(not self:is_installing(), "Package is already installing.")
-    local handle = self:new_handle()
-    local runner = InstallRunner:new(InstallLocation.global(), handle, semaphore)
-    runner:execute(opts, callback)
-    return handle
-end
-
----@return boolean
-function Package:uninstall()
-    return self:get_receipt()
-        :map(function(receipt)
-            self:unlink(receipt)
-            self:emit("uninstall:success", receipt)
-            registry:emit("package:uninstall:success", self, receipt)
-            return true
-        end)
-        :or_else(false)
-end
-
----@private
----@param receipt InstallReceipt
-function Package:unlink(receipt)
-    log.fmt_trace("Unlinking %s", self)
-    local install_path = self:get_install_path()
-
-    -- 1. Unlink
-    local linker = require "mason-core.installer.linker"
-    linker.unlink(self, receipt, InstallLocation.global()):get_or_throw()
-
-    -- 2. Remove installation artifacts
-    fs.sync.rmrf(install_path)
-end
-
-function Package:is_installed()
-    return registry.is_installed(self.name)
-end
-
-function Package:get_handle()
-    return Optional.of_nilable(self.handle)
-end
-
-function Package:get_install_path()
-    return InstallLocation.global():package(self.name)
-end
-
----@return Optional # Optional<InstallReceipt>
-function Package:get_receipt()
-    local receipt_path = path.concat { self:get_install_path(), "mason-receipt.json" }
-    if fs.sync.file_exists(receipt_path) then
-        local receipt = require "mason-core.receipt"
-        return Optional.of(receipt.InstallReceipt.from_json(vim.json.decode(fs.sync.read_file(receipt_path))))
-    end
-    return Optional.empty()
-end
-
----@return string?
-function Package:get_installed_version()
-    return self:get_receipt()
-        :and_then(
-            ---@param receipt InstallReceipt
-            function(receipt)
-                local source = receipt:get_source()
-                if source.id then
-                    return Purl.parse(source.id):map(_.prop "version"):ok()
-                else
-                    return Optional.empty()
-                end
-            end
-        )
-        :or_else(nil)
-end
-
----@return string
-function Package:get_latest_version()
-    return Purl.parse(self.spec.source.id)
-        :map(_.prop "version")
-        :get_or_throw(("Unable to retrieve version from malformed purl: %s."):format(self.spec.source.id))
-end
-
----@param opts? PackageInstallOpts
-function Package:is_installable(opts)
-    return require("mason-core.installer.compiler").parse(self.spec, opts or {}):is_success()
-end
-
----@return Result # Result<string[]>
-function Package:get_all_versions()
-    local compiler = require "mason-core.installer.compiler"
-    return Result.try(function(try)
-        ---@type Purl
-        local purl = try(Purl.parse(self.spec.source.id))
-        ---@type InstallerCompiler
-        local compiler = try(compiler.get_compiler(purl))
-        return compiler.get_versions(purl, self.spec.source)
-    end)
-end
-
-function Package:get_lsp_settings_schema()
-    local schema_file = InstallLocation.global()
-        :share(path.concat { "mason-schemas", "lsp", ("%s.json"):format(self.name) })
-    if fs.sync.file_exists(schema_file) then
-        return Result.pcall(vim.json.decode, fs.sync.read_file(schema_file), {
-            luanil = { object = true, array = true },
-        }):ok()
-    end
-    return Optional.empty()
-end
-function Package:get_aliases()
-    return require("mason-registry").get_package_aliases(self.name)
-end
-
-function Package:__tostring()
-    return ("Package(name=%s)"):format(self.name)
-end
-
-return Package
diff --git a/lua/mason-core/package/AbstractPackage.lua b/lua/mason-core/package/AbstractPackage.lua
new file mode 100644
index 00000000..b490fc87
--- /dev/null
+++ b/lua/mason-core/package/AbstractPackage.lua
@@ -0,0 +1,203 @@
+local EventEmitter = require "mason-core.EventEmitter"
+local InstallLocation = require "mason-core.installer.InstallLocation"
+local Optional = require "mason-core.optional"
+local Purl = require "mason-core.purl"
+local Result = require "mason-core.result"
+local _ = require "mason-core.functional"
+local fs = require "mason-core.fs"
+local log = require "mason-core.log"
+local path = require "mason-core.path"
+local settings = require "mason.settings"
+local Semaphore = require("mason-core.async.control").Semaphore
+
+---@alias PackageInstallOpts { version?: string, debug?: boolean, target?: string, force?: boolean, strict?: boolean, location?: InstallLocation }
+---@alias PackageUninstallOpts { bypass_permit?: boolean, location?: InstallLocation }
+
+---@class AbstractPackage : EventEmitter
+---@field name string
+---@field spec RegistryPackageSpec
+---@field private install_handle InstallHandle? The currently associated installation handle.
+---@field private uninstall_handle InstallHandle? The currently associated uninstallation handle.
+local AbstractPackage = {}
+AbstractPackage.__index = AbstractPackage
+setmetatable(AbstractPackage, { __index = EventEmitter })
+
+AbstractPackage.SEMAPHORE = Semaphore:new(settings.current.max_concurrent_installers)
+---@type PackageInstallOpts
+AbstractPackage.DEFAULT_INSTALL_OPTS = {
+    debug = false,
+    force = false,
+    strict = false,
+    target = nil,
+    version = nil,
+}
+
+---@param spec RegistryPackageSpec
+function AbstractPackage:new(spec)
+    local instance = EventEmitter.new(self)
+    instance.name = spec.name -- for convenient access
+    instance.spec = spec
+    return instance
+end
+
+---@return boolean
+function AbstractPackage:is_installing()
+    return self:get_install_handle()
+        :map(
+            ---@param handle InstallHandle
+            function(handle)
+                return not handle:is_closed()
+            end
+        )
+        :or_else(false)
+end
+
+---@return boolean
+function AbstractPackage:is_uninstalling()
+    return self:get_uninstall_handle()
+        :map(
+            ---@param handle InstallHandle
+            function(handle)
+                return not handle:is_closed()
+            end
+        )
+        :or_else(false)
+end
+
+function AbstractPackage:get_install_handle()
+    return Optional.of_nilable(self.install_handle)
+end
+
+function AbstractPackage:get_uninstall_handle()
+    return Optional.of_nilable(self.uninstall_handle)
+end
+
+---@param location InstallLocation
+function AbstractPackage:new_handle(location)
+    assert(location, "Cannot create new handle without a location.")
+    local InstallHandle = require "mason-core.installer.InstallHandle"
+    local handle = InstallHandle:new(self, location)
+    -- Ideally we'd decouple this and leverage Mason's event system, but to allow loading as little as possible during
+    -- setup (i.e. not load modules related to Mason's event system) of the mason.nvim plugin we explicitly call into
+    -- terminator here.
+    require("mason-core.terminator").register(handle)
+    return handle
+end
+
+---@param location? InstallLocation
+function AbstractPackage:new_install_handle(location)
+    location = location or InstallLocation.global()
+    log.fmt_trace("Creating new installation handle for %s", self)
+    self:get_install_handle():if_present(function(handle)
+        assert(handle:is_closed(), "Cannot create new install handle because existing handle is not closed.")
+    end)
+    self.install_handle = self:new_handle(location)
+    self:emit("install:handle", self.install_handle)
+    return self.install_handle
+end
+
+---@param location? InstallLocation
+function AbstractPackage:new_uninstall_handle(location)
+    location = location or InstallLocation.global()
+    log.fmt_trace("Creating new uninstallation handle for %s", self)
+    self:get_uninstall_handle():if_present(function(handle)
+        assert(handle:is_closed(), "Cannot create new uninstall handle because existing handle is not closed.")
+    end)
+    self.uninstall_handle = self:new_handle(location)
+    self:emit("uninstall:handle", self.uninstall_handle)
+    return self.uninstall_handle
+end
+
+---@param opts? PackageInstallOpts
+function AbstractPackage:is_installable(opts)
+    return require("mason-core.installer.compiler").parse(self.spec, opts or {}):is_success()
+end
+
+---@param location? InstallLocation
+---@return Optional # Optional<InstallReceipt>
+function AbstractPackage:get_receipt(location)
+    location = location or InstallLocation.global()
+    local receipt_path = location:receipt(self.name)
+    if fs.sync.file_exists(receipt_path) then
+        local receipt = require "mason-core.receipt"
+        return Optional.of(receipt.InstallReceipt.from_json(vim.json.decode(fs.sync.read_file(receipt_path))))
+    end
+    return Optional.empty()
+end
+
+---@param location? InstallLocation
+---@return boolean
+function AbstractPackage:is_installed(location)
+    error "Unimplemented."
+end
+
+---@return Result # Result<string[]>
+function AbstractPackage:get_all_versions()
+    local compiler = require "mason-core.installer.compiler"
+    return Result.try(function(try)
+        ---@type Purl
+        local purl = try(Purl.parse(self.spec.source.id))
+        ---@type InstallerCompiler
+        local compiler = try(compiler.get_compiler(purl))
+        return compiler.get_versions(purl, self.spec.source)
+    end)
+end
+
+---@return string
+function AbstractPackage:get_latest_version()
+    return Purl.parse(self.spec.source.id)
+        :map(_.prop "version")
+        :get_or_throw(("Unable to retrieve version from malformed purl: %s."):format(self.spec.source.id))
+end
+
+---@param location? InstallLocation
+---@return string?
+function AbstractPackage:get_installed_version(location)
+    return self:get_receipt(location)
+        :and_then(
+            ---@param receipt InstallReceipt
+            function(receipt)
+                local source = receipt:get_source()
+                if source.id then
+                    return Purl.parse(source.id):map(_.prop "version"):ok()
+                else
+                    return Optional.empty()
+                end
+            end
+        )
+        :or_else(nil)
+end
+
+---@param opts? PackageInstallOpts
+---@param callback? InstallRunnerCallback
+---@return InstallHandle
+function AbstractPackage:install(opts, callback)
+    error "Unimplemented."
+end
+
+---@param opts? PackageUninstallOpts
+---@param callback? InstallRunnerCallback
+---@return InstallHandle
+function AbstractPackage:uninstall(opts, callback)
+    error "Unimplemented."
+end
+
+---@private
+---@param location? InstallLocation
+function AbstractPackage:unlink(location)
+    location = location or InstallLocation.global()
+    log.fmt_trace("Unlinking", self, location)
+    local linker = require "mason-core.installer.linker"
+    return self:get_receipt(location):ok_or("Unable to find receipt."):and_then(function(receipt)
+        return linker.unlink(self, receipt, location)
+    end)
+end
+
+---@async
+---@private
+---@return Permit
+function AbstractPackage:acquire_permit()
+    error "Unimplemented."
+end
+
+return AbstractPackage
diff --git a/lua/mason-core/package/init.lua b/lua/mason-core/package/init.lua
new file mode 100644
index 00000000..09b0ebbf
--- /dev/null
+++ b/lua/mason-core/package/init.lua
@@ -0,0 +1,182 @@
+local AbstractPackage = require "mason-core.package.AbstractPackage"
+local InstallLocation = require "mason-core.installer.InstallLocation"
+local InstallRunner = require "mason-core.installer.InstallRunner"
+local Optional = require "mason-core.optional"
+local Result = require "mason-core.result"
+local UninstallRunner = require "mason-core.installer.UninstallRunner"
+local _ = require "mason-core.functional"
+local fs = require "mason-core.fs"
+local path = require "mason-core.path"
+local registry = require "mason-registry"
+local platform = require "mason-core.platform"
+local Semaphore = require("mason-core.async.control").Semaphore
+
+---@class Package : AbstractPackage
+---@field spec RegistryPackageSpec
+---@field local_semaphore Semaphore
+local Package = {}
+Package.__index = Package
+setmetatable(Package, { __index = AbstractPackage })
+
+---@param package_identifier string
+---@return string, string?
+Package.Parse = function(package_identifier)
+    local name, version = unpack(vim.split(package_identifier, "@"))
+    return name, version
+end
+
+---@alias PackageLanguage string
+
+---@type table<PackageLanguage, PackageLanguage>
+Package.Lang = setmetatable({}, {
+    __index = function(s, lang)
+        s[lang] = lang
+        return s[lang]
+    end,
+})
+
+---@enum PackageCategory
+Package.Cat = {
+    Compiler = "Compiler",
+    Runtime = "Runtime",
+    DAP = "DAP",
+    LSP = "LSP",
+    Linter = "Linter",
+    Formatter = "Formatter",
+}
+
+---@alias PackageLicense string
+
+---@type table<PackageLicense, PackageLicense>
+Package.License = setmetatable({}, {
+    __index = function(s, license)
+        s[license] = license
+        return s[license]
+    end,
+})
+
+---@class RegistryPackageSourceVersionOverride : RegistryPackageSource
+---@field constraint string
+
+---@class RegistryPackageSource
+---@field id string PURL-compliant identifier.
+---@field version_overrides? RegistryPackageSourceVersionOverride[]
+
+---@class RegistryPackageSchemas
+---@field lsp string?
+
+---@class RegistryPackageDeprecation
+---@field since string
+---@field message string
+
+---@alias RegistryPackageSpecSchema
+--- | '"registry+v1"'
+
+---@class RegistryPackageSpec
+---@field schema RegistryPackageSpecSchema
+---@field name string
+---@field description string
+---@field homepage string
+---@field licenses string[]
+---@field languages string[]
+---@field categories string[]
+---@field deprecation RegistryPackageDeprecation?
+---@field source RegistryPackageSource
+---@field schemas RegistryPackageSchemas?
+---@field bin table<string, string>?
+---@field share table<string, string>?
+---@field opt table<string, string>?
+
+---@param spec RegistryPackageSpec
+local function validate_spec(spec)
+    if platform.cached_features["nvim-0.11"] ~= 1 then
+        return
+    end
+    vim.validate("schema", spec.schema, _.equals "registry+v1", "registry+v1")
+    vim.validate("name", spec.name, "string")
+    vim.validate("description", spec.description, "string")
+    vim.validate("homepage", spec.homepage, "string")
+    vim.validate("licenses", spec.licenses, "table")
+    vim.validate("categories", spec.categories, "table")
+    vim.validate("languages", spec.languages, "table")
+    vim.validate("source", spec.source, "table")
+    vim.validate("bin", spec.bin, { "table", "nil" })
+    vim.validate("share", spec.share, { "table", "nil" })
+end
+
+---@param spec RegistryPackageSpec
+function Package:new(spec)
+    validate_spec(spec)
+    ---@type Package
+    local instance = AbstractPackage.new(self, spec)
+    instance.local_semaphore = Semaphore:new(1)
+    return instance
+end
+
+---@param opts? PackageInstallOpts
+---@param callback? InstallRunnerCallback
+---@return InstallHandle
+function Package:install(opts, callback)
+    opts = opts or {}
+    assert(not self:is_installing(), "Package is already installing.")
+    assert(not self:is_uninstalling(), "Package is uninstalling.")
+    opts = vim.tbl_extend("force", self.DEFAULT_INSTALL_OPTS, opts or {})
+
+    local handle = self:new_install_handle(opts.location)
+    registry:emit("package:install:handle", handle)
+    local runner = InstallRunner:new(handle, AbstractPackage.SEMAPHORE)
+
+    runner:execute(opts, callback)
+
+    return handle
+end
+
+---@param opts? PackageUninstallOpts
+---@param callback? fun(success: boolean, error: any)
+function Package:uninstall(opts, callback)
+    opts = opts or {}
+    assert(self:is_installed(opts.location), "Package is not installed.")
+    assert(not self:is_uninstalling(), "Package is already uninstalling.")
+    local handle = self:new_uninstall_handle(opts.location)
+    registry:emit("package:uninstall:handle", handle)
+    local runner = UninstallRunner:new(handle, AbstractPackage.SEMAPHORE)
+    runner:execute(opts, callback)
+    return handle
+end
+
+---@param location? InstallLocation
+function Package:is_installed(location)
+    location = location or InstallLocation.global()
+    local ok, stat = pcall(vim.loop.fs_stat, location:package(self.name))
+    if not ok or not stat then
+        return false
+    end
+    return stat.type == "directory"
+end
+
+function Package:get_lsp_settings_schema()
+    local schema_file = InstallLocation.global()
+        :share(path.concat { "mason-schemas", "lsp", ("%s.json"):format(self.name) })
+    if fs.sync.file_exists(schema_file) then
+        return Result.pcall(vim.json.decode, fs.sync.read_file(schema_file), {
+            luanil = { object = true, array = true },
+        }):ok()
+    end
+    return Optional.empty()
+end
+
+function Package:get_aliases()
+    return require("mason-registry").get_package_aliases(self.name)
+end
+
+---@async
+---@private
+function Package:acquire_permit()
+    return self.local_semaphore:acquire()
+end
+
+function Package:__tostring()
+    return ("Package(name=%s)"):format(self.name)
+end
+
+return Package
diff --git a/lua/mason-core/receipt.lua b/lua/mason-core/receipt.lua
index 63403503..847b8011 100644
--- a/lua/mason-core/receipt.lua
+++ b/lua/mason-core/receipt.lua
@@ -1,15 +1,11 @@
-local Result = require "mason-core.result"
-local fs = require "mason-core.fs"
-local path = require "mason-core.path"
-
 local M = {}
 
 ---@alias InstallReceiptSchemaVersion
 ---| '"1.0"'
 ---| '"1.1"'
----| '"1.2"'
+---| '"2.0"'
 
----@alias InstallReceiptSource {type: RegistryPackageSpecSchema, id: string}
+---@alias InstallReceiptSource {type: RegistryPackageSpecSchema, id: string, raw: RegistryPackageSource}
 
 ---@class InstallReceiptLinks
 ---@field bin? table<string, string>
@@ -22,6 +18,7 @@ local M = {}
 ---@field public metrics {start_time:integer, completion_time:integer}
 ---@field public source InstallReceiptSource
 ---@field public links InstallReceiptLinks
+---@field public install_options PackageInstallOpts
 local InstallReceipt = {}
 InstallReceipt.__index = InstallReceipt
 
@@ -33,6 +30,10 @@ function InstallReceipt.from_json(json)
     return InstallReceipt:new(json)
 end
 
+function InstallReceipt:__tostring()
+    return ("InstallReceipt(name=%s, purl=%s)"):format(self.name, self:get_source().id or "N/A")
+end
+
 function InstallReceipt:get_name()
     return self.name
 end
@@ -49,22 +50,30 @@ end
 
 ---@return InstallReceiptSource
 function InstallReceipt:get_source()
-    if self:is_schema_min "1.2" then
+    if self:is_schema_min "2.0" then
         return self.source
     end
     return self.primary_source --[[@as InstallReceiptSource]]
 end
 
+function InstallReceipt:get_raw_source()
+    if self:is_schema_min "2.0" then
+        return self.source.raw
+    else
+        return nil
+    end
+end
+
+function InstallReceipt:get_install_options()
+    return self.install_options
+end
+
 function InstallReceipt:get_links()
     return self.links
 end
 
----@async
----@param dir string
-function InstallReceipt:write(dir)
-    return Result.pcall(function()
-        fs.async.write_file(path.concat { dir, "mason-receipt.json" }, vim.json.encode(self))
-    end)
+function InstallReceipt:to_json()
+    return vim.json.encode(self)
 end
 
 ---@class InstallReceiptBuilder
@@ -96,6 +105,12 @@ function InstallReceiptBuilder:with_source(source)
     return self
 end
 
+---@param install_options PackageInstallOpts
+function InstallReceiptBuilder:with_install_options(install_options)
+    self.install_options = install_options
+    return self
+end
+
 ---@param typ '"bin"' | '"share"' | '"opt"'
 ---@param name string
 ---@param rel_path string
@@ -132,13 +147,15 @@ function InstallReceiptBuilder:build()
     assert(self.start_time, "start_time is required")
     assert(self.completion_time, "completion_time is required")
     assert(self.source, "source is required")
+    assert(self.install_options, "install_options is required")
     return InstallReceipt:new {
         name = self.name,
-        schema_version = "1.2",
+        schema_version = "2.0",
         metrics = {
             start_time = self.start_time,
             completion_time = self.completion_time,
         },
+        install_options = self.install_options,
         source = self.source,
         links = self.links,
     }