diff --git a/builtin/pure_ysh.py b/builtin/pure_ysh.py
index 4e2bcccf7b..a4e2f4b51e 100644
--- a/builtin/pure_ysh.py
+++ b/builtin/pure_ysh.py
@@ -4,7 +4,7 @@
 from __future__ import print_function
 
 from _devbuild.gen.runtime_asdl import cmd_value
-from _devbuild.gen.syntax_asdl import command_t, loc, loc_t
+from _devbuild.gen.syntax_asdl import loc
 from _devbuild.gen.value_asdl import value, value_e, value_t
 from core import error
 from core import state
@@ -14,7 +14,7 @@
 from mycpp import mylib
 from mycpp.mylib import tagswitch, NewDict
 
-from typing import TYPE_CHECKING, cast, Any, Dict, List
+from typing import TYPE_CHECKING, cast, Dict, List
 
 if TYPE_CHECKING:
     from display import ui
@@ -63,106 +63,6 @@ def Run(self, cmd_val):
         return 0
 
 
-class ctx_Context(object):
-    """For ctx push (context) { ... }"""
-
-    def __init__(self, mem, context):
-        # type: (state.Mem, Dict[str, value_t]) -> None
-        self.mem = mem
-        self.mem.PushContextStack(context)
-
-    def __enter__(self):
-        # type: () -> None
-        pass
-
-    def __exit__(self, type, value, traceback):
-        # type: (Any, Any, Any) -> None
-        self.mem.PopContextStack()
-
-
-class Ctx(vm._Builtin):
-
-    def __init__(self, mem, cmd_ev):
-        # type: (state.Mem, CommandEvaluator) -> None
-        self.mem = mem
-        self.cmd_ev = cmd_ev  # To run blocks
-
-    def _GetContext(self):
-        # type: () -> Dict[str, value_t]
-        ctx = self.mem.GetContext()
-        if ctx is None:
-            raise error.Expr(
-                "Could not find a context. Did you forget to 'ctx push'?",
-                loc.Missing)
-        return ctx
-
-    def _Push(self, context, block):
-        # type: (Dict[str, value_t], command_t) -> int
-        with ctx_Context(self.mem, context):
-            return self.cmd_ev.EvalCommand(block)
-
-    def _Set(self, updates):
-        # type: (Dict[str, value_t]) -> int
-        ctx = self._GetContext()
-        ctx.update(updates)
-        return 0
-
-    def _Emit(self, field, item, blame):
-        # type: (str, value_t, loc_t) -> int
-        ctx = self._GetContext()
-
-        if field not in ctx:
-            ctx[field] = value.List([])
-
-        UP_arr = ctx[field]
-        if UP_arr.tag() != value_e.List:
-            raise error.TypeErr(
-                UP_arr,
-                "Expected the context item '%s' to be a List" % (field), blame)
-
-        arr = cast(value.List, UP_arr)
-        arr.items.append(item)
-
-        return 0
-
-    def Run(self, cmd_val):
-        # type: (cmd_value.Argv) -> int
-        rd = typed_args.ReaderForProc(cmd_val)
-        _, arg_r = flag_util.ParseCmdVal('ctx',
-                                         cmd_val,
-                                         accept_typed_args=True)
-
-        verb, verb_loc = arg_r.ReadRequired2(
-            'Expected a verb (push, set, emit)')
-
-        if verb == "push":
-            context = rd.PosDict()
-            block = rd.RequiredBlock()
-            rd.Done()
-            arg_r.AtEnd()
-
-            return self._Push(context, block)
-
-        elif verb == "set":
-            updates = rd.RestNamed()
-            rd.Done()
-            arg_r.AtEnd()
-
-            return self._Set(updates)
-
-        elif verb == "emit":
-            field, field_loc = arg_r.ReadRequired2(
-                "A target field is required")
-            item = rd.PosValue()
-            rd.Done()
-            arg_r.AtEnd()
-
-            return self._Emit(field, item, field_loc)
-
-        else:
-            raise error.Usage("Unknown verb '%s'" % verb, verb_loc)
-
-
 class PushRegisters(vm._Builtin):
 
     def __init__(self, mem, cmd_ev):
diff --git a/core/shell.py b/core/shell.py
index d6cf69f66e..7dabd1f1cb 100644
--- a/core/shell.py
+++ b/core/shell.py
@@ -614,7 +614,6 @@ def Main(
     b[builtin_i.trap] = trap_osh.Trap(trap_state, parse_ctx, tracer, errfmt)
 
     b[builtin_i.shvar] = pure_ysh.Shvar(mem, search_path, cmd_ev)
-    b[builtin_i.ctx] = pure_ysh.Ctx(mem, cmd_ev)
     b[builtin_i.push_registers] = pure_ysh.PushRegisters(mem, cmd_ev)
 
     # Hay
diff --git a/frontend/builtin_def.py b/frontend/builtin_def.py
index 8ee6e38551..2db17eea3a 100644
--- a/frontend/builtin_def.py
+++ b/frontend/builtin_def.py
@@ -60,7 +60,6 @@
     'fork', 'forkwait',
     'redir', 'fopen',  # fopen is for backward compat
     'shvar',
-    'ctx',
 
     'invoke',
     'runproc',
diff --git a/spec/ysh-builtin-ctx.test.sh b/spec/ysh-builtin-ctx.test.sh
index 6d26065293..b18b74f227 100644
--- a/spec/ysh-builtin-ctx.test.sh
+++ b/spec/ysh-builtin-ctx.test.sh
@@ -2,6 +2,8 @@
 ## oils_failures_allowed: 0
 
 #### ctx push and set
+use $LIB_YSH/ctx.ysh
+
 var mydict = {}
 ctx push (mydict) {
   ctx set (key1="value1")
@@ -16,6 +18,8 @@ json write (mydict)
 ## END
 
 #### ctx emit
+use $LIB_YSH/ctx.ysh
+
 var p = {}
 ctx push (p) {
   ctx emit flag ({short_name: '-v'})
@@ -58,6 +62,8 @@ json write (p)
 ## END
 
 #### nested ctx
+use $LIB_YSH/ctx.ysh
+
 var a = {}
 var b = {}
 ctx push (a) {
@@ -78,6 +84,8 @@ json write (b)
 ## END
 
 #### error in context
+use $LIB_YSH/ctx.ysh
+
 var a = {}
 try {
   ctx push (a) {
@@ -91,6 +99,8 @@ status=100
 ## END
 
 #### no context, set
+use $LIB_YSH/ctx.ysh
+
 ctx set (bad=true)
 echo status=$_status
 ## status: 3
@@ -98,6 +108,8 @@ echo status=$_status
 ## END
 
 #### no context, emit
+use $LIB_YSH/ctx.ysh
+
 ctx emit bad (true)
 echo status=$_status
 ## status: 3
@@ -105,6 +117,8 @@ echo status=$_status
 ## END
 
 #### mini-parseArgs
+use $LIB_YSH/ctx.ysh
+
 proc parser (; place ; ; block_def) {
   var p = {}
   ctx push (p; ; block_def)
@@ -159,6 +173,7 @@ json write (spec)
 ## END
 
 #### ctx with value.Place, not List/Dict (error location bug fix)
+use $LIB_YSH/ctx.ysh
 
 ctx push (&p) {
   true
diff --git a/stdlib/ysh/args.ysh b/stdlib/ysh/args.ysh
index 9143d15fff..5375fdb242 100644
--- a/stdlib/ysh/args.ysh
+++ b/stdlib/ysh/args.ysh
@@ -26,6 +26,8 @@
 #
 # echo "Verbose $[args.verbose]"
 
+source $LIB_YSH/ctx.ysh
+
 # TODO: See list
 # - It would be nice to keep `flag` and `arg` private, injecting them into the
 #   proc namespace only within `Args`
diff --git a/stdlib/ysh/ctx.ysh b/stdlib/ysh/ctx.ysh
new file mode 100644
index 0000000000..51ba49625c
--- /dev/null
+++ b/stdlib/ysh/ctx.ysh
@@ -0,0 +1,32 @@
+var contextStack = []
+
+proc push (; context;; block) {
+  if (type(context) !== 'Dict') {
+    error "Expected context to be a Dict" (code=3)
+  }
+
+  call contextStack->append(context)
+  try {
+    use ///ysh/ctx.ysh
+    call io->eval(block, vars={ctx})
+  }
+  call contextStack->pop()
+  return $[_error.code]
+}
+
+proc set (;; ...named) {
+  var context = contextStack[-1]
+  for k, v in (named) {
+    setvar context[k] = v
+  }
+}
+
+proc emit (field; item) {
+  var context = contextStack[-1]
+  if (field not in context) {
+    setvar context[field] = []
+  }
+  call context[field]->append(item)
+}
+
+var __provide__ = :| push set emit |