diff --git a/.github/workflows/ci.yml b/.github/workflows/CI.yml
similarity index 100%
rename from .github/workflows/ci.yml
rename to .github/workflows/CI.yml
diff --git a/.github/workflows/CassetteBaseCI.yml b/.github/workflows/CassetteBaseCI.yml
new file mode 100644
index 0000000..2a7637c
--- /dev/null
+++ b/.github/workflows/CassetteBaseCI.yml
@@ -0,0 +1,53 @@
+name: CassetteBaseCI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  test:
+    name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false # don't stop CI even when one of them fails
+      matrix:
+        include:
+          - version: '1' # current stable
+            os: ubuntu-latest
+            arch: x64
+          - version: '1.10' # lowerest version supported
+            os: ubuntu-latest
+            arch: x64
+          - version: '1.11-nightly' # next release
+            os: ubuntu-latest
+            arch: x64
+          - version: 'nightly' # dev
+            os: ubuntu-latest
+            arch: x64
+          - version: '1' # x86 ubuntu
+            os: ubuntu-latest
+            arch: x86
+          - version: '1' # x86 windows
+            os: windows-latest
+            arch: x86
+          - version: '1' # x64 windows
+            os: windows-latest
+            arch: x64
+          - version: '1' # x64 macOS
+            os: macos-latest
+            arch: x64
+    steps:
+      - uses: actions/checkout@v4
+      - uses: julia-actions/setup-julia@v2
+        with:
+          version: ${{ matrix.version }}
+          arch: ${{ matrix.arch }}
+      - name: test CassetteBase
+        shell: julia --color=yes --project=. {0}    # this is necessary for the next command to work on Windows
+        run: 'using Pkg; Pkg.activate("CassetteBase"); Pkg.instantiate(); Pkg.test(coverage=true)'
+      - uses: julia-actions/julia-processcoverage@v1
+      - uses: codecov/codecov-action@v4
+        with:
+          file: ./lcov.info
diff --git a/CassetteBase/LICENSE.md b/CassetteBase/LICENSE.md
new file mode 100644
index 0000000..d325b45
--- /dev/null
+++ b/CassetteBase/LICENSE.md
@@ -0,0 +1,19 @@
+Copyright (c) 2024 JuliaHub, Inc. and other contributors.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/CassetteBase/Project.toml b/CassetteBase/Project.toml
new file mode 100644
index 0000000..032e484
--- /dev/null
+++ b/CassetteBase/Project.toml
@@ -0,0 +1,13 @@
+name = "CassetteBase"
+uuid = "6dd3e646-b1c5-42c7-94be-00277fa12e22"
+authors = ["Shuhei Kadowaki <aviatesk@gmail.com>"]
+version = "0.1.0"
+
+[compat]
+julia = "1.10"
+
+[extras]
+Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+
+[targets]
+test = ["Test"]
diff --git a/CassetteBase/README.md b/CassetteBase/README.md
new file mode 100644
index 0000000..69cf5ef
--- /dev/null
+++ b/CassetteBase/README.md
@@ -0,0 +1 @@
+# CassetteBase.jl
diff --git a/CassetteBase/src/CassetteBase.jl b/CassetteBase/src/CassetteBase.jl
new file mode 100644
index 0000000..6d83acc
--- /dev/null
+++ b/CassetteBase/src/CassetteBase.jl
@@ -0,0 +1,165 @@
+module CassetteBase
+
+export cassette_transform!, generate_internalerr_ex, generate_lambda_ex
+
+using Core.IR
+using Core: SimpleVector
+
+function cassette_transform!(src::CodeInfo, mi::MethodInstance, nargs::Int,
+                             selfname::Symbol, fargsname::Symbol)
+    method = mi.def::Method
+    mnargs = Int(method.nargs)
+
+    src.slotnames = Symbol[selfname, fargsname, src.slotnames[mnargs+1:end]...]
+    src.slotflags = UInt8[ 0x00,     0x00,      src.slotflags[mnargs+1:end]...]
+
+    code = src.code
+    fargsslot = SlotNumber(2)
+    precode = Any[]
+    local ssaid = 0
+    for i = 1:mnargs
+        if method.isva && i == mnargs
+            tuplecall = Expr(:call, tuple)
+            for j = i:nargs
+                push!(precode, Expr(:call, getfield, fargsslot, j))
+                ssaid += 1
+                push!(tuplecall.args, SSAValue(ssaid))
+            end
+            push!(precode, tuplecall)
+        else
+            push!(precode, Expr(:call, getfield, fargsslot, i))
+        end
+        ssaid += 1
+    end
+    prepend!(code, precode)
+    @static if VERSION < v"1.12.0-DEV.173"
+        prepend!(src.codelocs, [0 for i = 1:ssaid])
+    else
+        di = Core.Compiler.DebugInfoStream(mi, src.debuginfo, length(code))
+        src.debuginfo = Core.DebugInfo(di, length(code))
+    end
+    prepend!(src.ssaflags, [0x00 for i = 1:ssaid])
+    src.ssavaluetypes += ssaid
+    if @static isdefined(Base, :__has_internal_change) && Base.__has_internal_change(v"1.12-alpha", :codeinfonargs)
+        src.nargs = 2
+        src.isva = true
+    end
+
+    function map_slot_number(slot::Int)
+        @assert slot ≥ 1
+        if 1 ≤ slot ≤ mnargs
+            if method.isva && slot == mnargs
+                return SSAValue(ssaid)
+            else
+                return SSAValue(slot)
+            end
+        else
+            return SlotNumber(slot - mnargs + 2)
+        end
+    end
+    map_ssa_value(id::Int) = id + ssaid
+    for i = (ssaid+1:length(code))
+        code[i] = transform_stmt(code[i], map_slot_number, map_ssa_value, mi.def.sig, mi.sparam_vals)
+    end
+
+    src.edges = MethodInstance[mi]
+    src.method_for_inference_limit_heuristics = method
+
+    return src
+end
+
+function transform_stmt(@nospecialize(x), map_slot_number, map_ssa_value, @nospecialize(spsig), sparams::SimpleVector)
+    transform(@nospecialize x′) = transform_stmt(x′, map_slot_number, map_ssa_value, spsig, sparams)
+    if isa(x, Expr)
+        head = x.head
+        if head === :call
+            return Expr(:call, SlotNumber(1), map(transform, x.args[1:end])...)
+        elseif head === :foreigncall
+            arg1 = x.args[1]
+            if Meta.isexpr(arg1, :call)
+                # first argument of :foreigncall may be a magic tuple call, and it should be preserved
+                arg1 = Expr(:call, map(transform, arg1.args)...)
+            else
+                arg1 = transform(x.args[1])
+            end
+            arg2 = @ccall jl_instantiate_type_in_env(x.args[2]::Any, spsig::Any, sparams::Ptr{Any})::Any
+            arg3 = Core.svec(Any[
+                    @ccall jl_instantiate_type_in_env(argt::Any, spsig::Any, sparams::Ptr{Any})::Any
+                    for argt in x.args[3]::SimpleVector ]...)
+            return Expr(:foreigncall, arg1, arg2, arg3, map(transform, x.args[4:end])...)
+        elseif head === :enter
+            return Expr(:enter, map_ssa_value(x.args[1]::Int))
+        elseif head === :static_parameter
+            return sparams[x.args[1]::Int]
+        elseif head === :isdefined
+            arg1 = x.args[1]
+            if Meta.isexpr(arg1, :static_parameter)
+                return 1 ≤ arg1.args[1]::Int ≤ length(sparams)
+            end
+        end
+        return Expr(head, map(transform, x.args)...)
+    elseif isa(x, GotoNode)
+        return GotoNode(map_ssa_value(x.label))
+    elseif isa(x, GotoIfNot)
+        return GotoIfNot(transform(x.cond), map_ssa_value(x.dest))
+    elseif isa(x, ReturnNode)
+        return ReturnNode(transform(x.val))
+    elseif isa(x, SlotNumber)
+        return map_slot_number(x.id)
+    elseif isa(x, NewvarNode)
+        return NewvarNode(map_slot_number(x.slot.id))
+    elseif isa(x, SSAValue)
+        return SSAValue(map_ssa_value(x.id))
+    elseif @static @isdefined(EnterNode) && isa(x, EnterNode)
+        if isdefined(x, :scope)
+            return EnterNode(map_ssa_value(x.catch_dest), transform(x.scope))
+        else
+            return EnterNode(map_ssa_value(x.catch_dest))
+        end
+    end
+    return x
+end
+
+struct CassetteInternalError
+    err
+    bt::Vector
+    context::Symbol
+    metadata  # allow preserving arbitrary data for debugging
+    function CassetteInternalError(err, bt::Vector, context::Symbol, metadata=nothing)
+        @nospecialize err metadata
+        new(err, bt, context, metadata)
+    end
+end
+function Base.showerror(io::IO, err::CassetteInternalError)
+    print(io, "Internal error happened in `$(err.context)`:")
+    println(io)
+    buf = IOBuffer()
+    ioctx = IOContext(buf, IOContext(io))
+    Base.showerror(ioctx, err.err)
+    Base.show_backtrace(ioctx, err.bt)
+    printstyled(io, " ┌", '─'^48, '\n'; color=:red)
+    for l in split(String(take!(buf)), '\n')
+        printstyled(io, " │ "; color=:red)
+        println(io, l)
+    end
+    printstyled(io, " └", '─'^48; color=:red)
+end
+
+function generate_internalerr_ex(err, bt::Vector, context::Symbol,
+                                 world::UInt, source::LineNumberNode,
+                                 argnames::SimpleVector, spnames::SimpleVector,
+                                 metadata=nothing)
+    @nospecialize err metadata
+    throw_ex = :(throw($CassetteInternalError(
+        $(QuoteNode(err)), $bt, $(QuoteNode(context)), $(QuoteNode(metadata)))))
+    return generate_lambda_ex(world, source, argnames, spnames, throw_ex)
+end
+
+function generate_lambda_ex(world::UInt, source::LineNumberNode,
+                            argnames::SimpleVector, spnames::SimpleVector,
+                            body::Expr)
+    stub = Core.GeneratedFunctionStub(identity, argnames, spnames)
+    return stub(world, source, body)
+end
+
+end # module CassetteBase
diff --git a/CassetteBase/test/runtests.jl b/CassetteBase/test/runtests.jl
new file mode 100644
index 0000000..2496132
--- /dev/null
+++ b/CassetteBase/test/runtests.jl
@@ -0,0 +1,5 @@
+using Test
+
+@testset "CassetteBase" begin
+    @testset "test_basic.jl" include("test_basic.jl")
+end
diff --git a/CassetteBase/test/test_basic.jl b/CassetteBase/test/test_basic.jl
new file mode 100644
index 0000000..f065221
--- /dev/null
+++ b/CassetteBase/test/test_basic.jl
@@ -0,0 +1,83 @@
+module test_basic
+
+using Test, CassetteBase
+
+function make_basic_generator(selfname::Symbol, fargsname::Symbol, raise::Bool)
+    function basic_generator(world::UInt, source::LineNumberNode, passtype, fargtypes)
+        @nospecialize passtype fargtypes
+        try
+            return generate_basic_src(world, source, passtype, fargtypes,
+                                      selfname, fargsname; raise)
+        catch err
+            # internal error happened - return an expression to raise the special exception
+            return generate_internalerr_ex(
+                err, #=bt=#catch_backtrace(), #=context=#:basic_generator, world, source,
+                #=argnames=#Core.svec(selfname, fargsname), #=spnames=#Core.svec(),
+                #=metadata=#(; world, source, passtype, fargtypes))
+        end
+    end
+end
+function generate_basic_src(world::UInt, source::LineNumberNode, passtype, fargtypes,
+                            selfname::Symbol, fargsname::Symbol; raise::Bool)
+    @nospecialize passtype fargtypes
+    tt = Base.to_tuple_type(fargtypes)
+    match = Base._which(tt; raise, world)
+    match === nothing && return nothing # method match failed – the fallback implementation will raise a proper MethodError
+    mi = Core.Compiler.specialize_method(match)
+    src = Core.Compiler.retrieve_code_info(mi, world)
+    src === nothing && return nothing # code generation failed - the fallback implementation will re-raise it
+    cassette_transform!(src, mi, length(fargtypes), selfname, fargsname)
+    return src
+end
+
+struct BasicPass end
+@eval function (pass::BasicPass)(fargs...)
+    $(Expr(:meta, :generated, make_basic_generator(:pass, :fargs, #=raise=#false)))
+    return first(fargs)(Base.tail(fargs)...)
+end
+let pass = BasicPass()
+    @test pass(sin, 1) == sin(1)
+    @test_throws MethodError pass("1") do x; sin(x); end
+end
+
+struct RaisePass end
+@eval function (pass::RaisePass)(fargs...)
+    $(Expr(:meta, :generated, make_basic_generator(:pass, :fargs, #=raise=#true)))
+    return first(fargs)(Base.tail(fargs)...)
+end
+let pass = RaisePass()
+    @test pass(sin, 1) == sin(1)
+    @test_throws CassetteBase.CassetteInternalError pass("1") do x; sin(x); end
+    local err
+    try
+        pass("1") do
+            sin(x)
+        end
+    catch e
+        err = e
+    end
+    @test @isdefined(err)
+    @test err isa CassetteBase.CassetteInternalError
+    msg = let
+        buf = IOBuffer()
+        showerror(buf, err)
+        String(take!(buf))
+    end
+    @test occursin("Internal error happened in `basic_generator`:", msg)
+    local err_expected
+    try
+        Base._which(Tuple{typeof(sin),String})
+    catch e
+        err_expected = e
+    end
+    @test @isdefined(err_expected)
+    @test err.err == err_expected
+    msg_expected = let
+        buf = IOBuffer()
+        showerror(buf, err_expected)
+        String(take!(buf))
+    end
+    @test occursin(msg_expected, msg)
+end
+
+end # module test_basic
diff --git a/LICENSE.md b/LICENSE.md
index 66349e5..d325b45 100644
--- a/LICENSE.md
+++ b/LICENSE.md
@@ -1,4 +1,4 @@
-Copyright (c) 2022 JuliaHub, Inc. and other contributors.
+Copyright (c) 2024 JuliaHub, Inc. and other contributors.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal