diff --git a/clues.go b/clues.go
index 922e4ab..7b8b6f6 100644
--- a/clues.go
+++ b/clues.go
@@ -194,7 +194,7 @@ func AddCommentTo(
 }
 
 // ---------------------------------------------------------------------------
-// hooks
+// error label counter
 // ---------------------------------------------------------------------------
 
 // AddLabelCounter embeds an Adder interface into this context. Any already
@@ -209,7 +209,7 @@ func AddLabelCounter(ctx context.Context, counter Adder) context.Context {
 	return setDefaultNodeInCtx(ctx, nn)
 }
 
-// AddLabelCounterTo embeds an Adder interface into this context. Any already
+// AddLabelCounterTo embeds an Adder interface within a namespace. Any already
 // embedded Adder will get replaced.  When adding Labels to a clues.Err the
 // LabelCounter will use the label as the key for the Add call, and increment
 // the count of that label by one.
@@ -224,3 +224,63 @@ func AddLabelCounterTo(
 
 	return setNodeInCtx(ctx, namespace, nn)
 }
+
+// ---------------------------------------------------------------------------
+// comments
+// ---------------------------------------------------------------------------
+
+// AddProxy attaches up a new clues proxy in the context.  All proxies are
+// passed down to all descendants which branch off of this context.  Whenever
+// a clues is added to the context, it gets added to the proxy as well.  As
+// a result, any clues added to the context in descendent funcs will appear in
+// this context as well.
+//
+// If the proxyID is an empty string, a random id will be generated.
+//
+// If isolateProxyValues is true, the proxy will namespace all of its values
+// using the proxyID to avoid clobbering any existing values.
+//
+// Proxy support is specifically useful in a unique situation: when you are
+// able to both pass in a ctx and also able to add clues data to it, but also
+// unable to later retrieve the ctx or to bind the ctx values into an error.
+// This case can manifest when passing ad-hoc functions or middleware to
+// callers who limit options to control for error returns.
+func AddProxy(
+	ctx context.Context,
+	proxyID string,
+	isolateProxyValues bool,
+) context.Context {
+	nc := nodeFromCtx(ctx, defaultNamespace)
+	nn := nc.addValues(nil)
+	nn = nn.addProxy(proxyID, isolateProxyValues)
+
+	return setDefaultNodeInCtx(ctx, nn)
+}
+
+// AddProxyTo attaches up a new clues proxy within the context namespace.
+// All proxies are passed down to all descendants which branch off of this
+// context.  Whenever a clues is added to the context, it gets added to the
+// proxy as well.  As a result, any clues added to the context in descendent
+// funcs will appear in this context as well.
+//
+// If the proxyID is an empty string, a random id will be generated.
+//
+// If isolateProxyValues is true, the proxy will namespace all of its values
+// using the proxyID to avoid clobbering any existing values.
+//
+// Proxy support is specifically useful in a unique situation: when you are
+// able to both pass in a ctx and also able to add clues data to it, but also
+// unable to later retrieve the ctx or to bind the ctx values into an error.
+// This case can manifest when passing ad-hoc functions or middleware to
+// callers who limit options to control for error returns.
+func AddProxyTo(
+	ctx context.Context,
+	namespace, proxyID string,
+	isolateProxyValues bool,
+) context.Context {
+	nc := nodeFromCtx(ctx, ctxKey(namespace))
+	nn := nc.addValues(nil)
+	nn = nn.addProxy(proxyID, isolateProxyValues)
+
+	return setNodeInCtx(ctx, namespace, nn)
+}
diff --git a/clues_test.go b/clues_test.go
index a46b9c9..76fa974 100644
--- a/clues_test.go
+++ b/clues_test.go
@@ -12,6 +12,14 @@ import (
 	"golang.org/x/exp/slices"
 )
 
+func mapEquals(
+	t *testing.T,
+	ctx context.Context,
+	expect msa,
+) {
+	mustEquals(t, expect, clues.In(ctx).Map(), true)
+}
+
 func mustEquals[K comparable, V any](
 	t *testing.T,
 	expect, got map[K]V,
@@ -21,7 +29,9 @@ func mustEquals[K comparable, V any](
 
 	if hasCluesTrace && len(g) > 0 {
 		if _, ok := g["clues_trace"]; !ok {
-			t.Error("expected map to contain key [clues_trace]")
+			t.Errorf(
+				"expected map to contain key [clues_trace]\ngot: %+v",
+				g)
 		}
 		delete(g, "clues_trace")
 	}
@@ -424,6 +434,154 @@ func TestAddTraceNameTo(t *testing.T) {
 	}
 }
 
+func TestProxy(t *testing.T) {
+	table := []struct {
+		name     string
+		kvs      [][]string
+		isolated bool
+		expectM  msa
+		expectS  sa
+	}{
+		{
+			name:     "single",
+			kvs:      [][]string{{"k", "v"}},
+			isolated: false,
+			expectM:  msa{"k": "v"},
+			expectS:  sa{"k", "v"},
+		},
+		{
+			name:     "multiple",
+			kvs:      [][]string{{"a", "1"}, {"b", "2"}},
+			isolated: false,
+			expectM:  msa{"k": "v", "a": "1", "b": "2"},
+			expectS:  sa{"k", "v", "a", "1", "b", "2"},
+		},
+		{
+			name:     "duplicates",
+			kvs:      [][]string{{"a", "1"}, {"a", "2"}},
+			isolated: false,
+			expectM:  msa{"k": "v", "a": "2"},
+			expectS:  sa{"k", "v", "a", "2"},
+		},
+		{
+			name:     "single isolated",
+			kvs:      [][]string{{"k", "v"}},
+			isolated: true,
+			expectM:  msa{"k": "v", "proxy_pfx_k": "v"},
+			expectS:  sa{"k", "v", "proxy_pfx_k", "v"},
+		},
+		{
+			name:     "multiple isolated",
+			kvs:      [][]string{{"a", "1"}, {"b", "2"}},
+			isolated: true,
+			expectM:  msa{"k": "v", "proxy_pfx_a": "1", "proxy_pfx_b": "2"},
+			expectS:  sa{"k", "v", "proxy_pfx_a", "1", "proxy_pfx_b", "2"},
+		},
+		{
+			name:     "duplicates isolated",
+			kvs:      [][]string{{"a", "1"}, {"a", "2"}},
+			isolated: true,
+			expectM:  msa{"k": "v", "proxy_pfx_a": "2"},
+			expectS:  sa{"k", "v", "proxy_pfx_a", "2"},
+		},
+	}
+	for _, test := range table {
+		t.Run(test.name, func(t *testing.T) {
+			ctx := context.WithValue(context.Background(), testCtx{}, "instance")
+			ctx = clues.Add(ctx, "k", "v")
+
+			check := msa{"k": "v"}
+
+			mustEquals(t, check, clues.In(ctx).Map(), true)
+
+			ctx = clues.AddProxy(ctx, "proxy_pfx", test.isolated)
+
+			for _, kv := range test.kvs {
+				clues.Add(ctx, kv[0], kv[1])
+
+				if test.isolated {
+					check["proxy_pfx_"+kv[0]] = kv[1]
+				} else {
+					check[kv[0]] = kv[1]
+				}
+
+				mustEquals(t, check, clues.In(ctx).Map(), true)
+			}
+
+			assert(
+				t, ctx, "",
+				test.expectM, msa{},
+				test.expectS, sa{})
+		})
+	}
+}
+
+func TestProxy_multipleLayers(t *testing.T) {
+	ctx := clues.Add(context.Background(), 1, 1)
+	pxyCtx := clues.AddProxy(ctx, "p1", true)
+
+	t.Run("1", func(t *testing.T) {
+		mapEquals(t, ctx, msa{"1": 1})
+		mapEquals(t, pxyCtx, msa{"1": 1})
+	})
+
+	ctx2 := clues.Add(pxyCtx, 2, 2)
+	pxyCtx2 := clues.AddProxy(ctx2, "p2", true)
+
+	t.Run("2", func(t *testing.T) {
+		mapEquals(t, ctx, msa{"1": 1})
+		mapEquals(t, pxyCtx, msa{
+			"1":    1,
+			"p1_2": 2,
+		})
+		mapEquals(t, ctx2, msa{
+			"1":    1,
+			"2":    2,
+			"p1_2": 2,
+		})
+		mapEquals(t, pxyCtx2, msa{
+			"1": 1,
+			"2": 2,
+		})
+	})
+
+	ctx3 := clues.Add(pxyCtx2, 3, 3)
+
+	t.Run("3", func(t *testing.T) {
+		mapEquals(t, ctx, msa{"1": 1})
+		// proxy 1 is still accumulating all the values added
+		// to descendant contexts, even after proxy 2 replaces
+		// it, because proxy 2 should maintain an ancestry ref
+		// to proxy 1.
+		mapEquals(t, pxyCtx, msa{
+			"1":    1,
+			"p1_2": 2,
+			"p1_3": 3,
+		})
+		mapEquals(t, ctx2, msa{
+			"1":    1,
+			"2":    2,
+			"p1_2": 2,
+			"p1_3": 3,
+		})
+		// ctxs up to ctx2 only have a reference to proxy 1.
+		// once we add proxy 2, the contexts from that point
+		// on maintain only that reference, and no longer
+		// retrieve proxy 1 values.
+		mapEquals(t, pxyCtx2, msa{
+			"1":    1,
+			"2":    2,
+			"p2_3": 3,
+		})
+		mapEquals(t, ctx3, msa{
+			"1":    1,
+			"2":    2,
+			"3":    3,
+			"p2_3": 3,
+		})
+	})
+}
+
 func TestImmutableCtx(t *testing.T) {
 	var (
 		ctx     = context.Background()
diff --git a/datanode.go b/datanode.go
index e89d7e8..cc15a21 100644
--- a/datanode.go
+++ b/datanode.go
@@ -40,6 +40,11 @@ type dataNode struct {
 	// full trace along the node's ancestry path in the tree.
 	id string
 
+	// isolationPrefix is an optional namespacing configuration.  When non-empty,
+	// all values will update their key with the isolationPrefix.
+	// IE: "foo": "bar" becomes "pfx_foo": "bar"
+	isolationPrefix string
+
 	// values are they arbitrary key:value pairs that appear in clues when callers
 	// use the Add(ctx, k, v) or err.With(k, v) adders.  Each key-value pair added
 	// to the node is used to produce the final set of Values() in the dataNode,
@@ -60,6 +65,37 @@ type dataNode struct {
 	// Errors will only utilize the first labelCounter they find.  The tree is searched
 	// from leaf to root when looking for populated labelCounters.
 	labelCounter Adder
+
+	// proxies contain all proxies (keyed by proxyID) attached to this context.
+	// Once a proxy has been added to this map, it should be passed down to
+	// all descendant dataNodes.  Therefore, any given child of a data node should
+	// have an equal or greater number of proxies compared to its parent.
+	//
+	// In the hierarchy of data collision priority, proxies have higher priority
+	// than other context data (eg: last descendant's data wins), but lower
+	// priority than any error values.
+	//
+	// Proxies construct their own data tree.  The root of the tree is the first
+	// proxy added to the context.  That proxy will get passed down to all descendants.
+	// If any descendant of the primary dataNode attaches another proxy, that new
+	// proxy becomes a descenant of the currently existing proxy.  This way, when we
+	// add a value to a proxy, we are able to walk its ascendancy tree to add the same
+	// valus to all ancestory proxies, thereby guaranteeing that every aded proxy gets
+	// the same data.
+	proxy *dataNode
+}
+
+// spawnDescendant generates a new dataNode that is a descendant of the current
+// node.  A descendant maintains a pointer to its parent, and carries any genetic
+// necessities (ie, copies of fields) that must be present for continued functionality.
+func (dn *dataNode) spawnDescendant() *dataNode {
+	return &dataNode{
+		parent:       dn,
+		labelCounter: dn.labelCounter,
+		// proxies construct their own data tree, and must be passed
+		// from parent to child to maintain references.
+		proxy: dn.proxy,
+	}
 }
 
 // ---------------------------------------------------------------------------
@@ -126,11 +162,38 @@ func (dn *dataNode) addValues(m map[string]any) *dataNode {
 		m = map[string]any{}
 	}
 
-	return &dataNode{
-		parent:       dn,
-		id:           makeNodeID(),
-		values:       maps.Clone(m),
-		labelCounter: dn.labelCounter,
+	spawn := dn.spawnDescendant()
+	spawn.id = makeNodeID()
+	spawn.setValues(m)
+
+	// if a proxy exists, add the same values to the proxy lineage.
+	if dn.proxy != nil {
+		for _, ancestor := range dn.proxy.ancestors() {
+			ancestor.setValues(m)
+		}
+	}
+
+	return spawn
+}
+
+// setValues is a helper called by addValues.
+func (dn *dataNode) setValues(m map[string]any) {
+	if len(m) == 0 {
+		return
+	}
+
+	if len(dn.values) == 0 {
+		dn.values = map[string]any{}
+	}
+
+	if len(dn.isolationPrefix) == 0 {
+		maps.Copy(dn.values, m)
+		return
+	}
+
+	for k, v := range m {
+		k = dn.isolationPrefix + "_" + k
+		dn.values[k] = v
 	}
 }
 
@@ -140,30 +203,35 @@ func (dn *dataNode) trace(name string) *dataNode {
 		name = makeNodeID()
 	}
 
-	return &dataNode{
-		parent:       dn,
-		id:           name,
-		values:       map[string]any{},
-		labelCounter: dn.labelCounter,
-	}
+	spawn := dn.spawnDescendant()
+	spawn.id = name
+
+	return spawn
 }
 
 // ---------------------------------------------------------------------------
 // getters
 // ---------------------------------------------------------------------------
 
-// lineage runs the fn on every valueNode in the ancestry tree,
-// starting at the root and ending at the dataNode.
-func (dn *dataNode) lineage(fn func(id string, vs map[string]any)) {
+// ancestors builds an ancestor lineage from this dataNode.
+// * the root dataNode is the zeroth, the leaf is last entry.
+func (dn *dataNode) ancestors() []*dataNode {
+	return stackParentOntoSelf(dn)
+}
+
+// a recursive function, purely for building out dn.ancestors.
+func stackParentOntoSelf(dn *dataNode) []*dataNode {
 	if dn == nil {
-		return
+		return []*dataNode{}
 	}
 
+	nodes := []*dataNode{}
+
 	if dn.parent != nil {
-		dn.parent.lineage(fn)
+		nodes = stackParentOntoSelf(dn.parent)
 	}
 
-	fn(dn.id, dn.values)
+	return append(nodes, dn)
 }
 
 // In returns the default dataNode from the context.
@@ -184,24 +252,39 @@ func InNamespace(ctx context.Context, namespace string) *dataNode {
 // take priority over ancestors in cases of collision.
 func (dn *dataNode) Map() map[string]any {
 	var (
-		m    = map[string]any{}
-		idsl = []string{}
+		m      = map[string]any{}
+		traces = []string{}
 	)
 
-	dn.lineage(func(id string, vs map[string]any) {
-		if len(id) > 0 {
-			idsl = append(idsl, id)
-		}
+	// build a root-to-leaf lineage through the tree.
+	lineage := dn.ancestors()
 
-		for k, v := range vs {
-			m[k] = v
+	// copy the values of each ancestor onto the map.
+	// descendant values will clobber ancestor values.
+	for _, ancestor := range lineage {
+		maps.Copy(m, ancestor.values)
+
+		if len(ancestor.id) > 0 {
+			traces = append(traces, ancestor.id)
 		}
-	})
+	}
 
-	if len(idsl) > 0 {
-		m["clues_trace"] = strings.Join(idsl, ",")
+	// if a proxy exists, it gets the highest priority
+	// for representing all unattached descendant data
+	// beyond the leaf.
+	if dn.proxy != nil {
+		// don't call proxy.Values() here, we don't want
+		// any of the proxy parent data in this result.
+		maps.Copy(m, dn.proxy.values)
+
+		if len(dn.proxy.id) > 0 {
+			traces = append(traces, "["+dn.proxy.id+"]")
+		}
 	}
 
+	// construct a clues trace of ids from root to leaf.
+	m["clues_trace"] = strings.Join(traces, ",")
+
 	return m
 }
 
@@ -266,11 +349,10 @@ func (dn *dataNode) addComment(
 		return dn
 	}
 
-	return &dataNode{
-		parent:       dn,
-		labelCounter: dn.labelCounter,
-		comment:      newComment(depth+1, msg, vs...),
-	}
+	spawn := dn.spawnDescendant()
+	spawn.comment = newComment(depth+1, msg, vs...)
+
+	return spawn
 }
 
 // comments allows us to put a stringer on a slice of comments.
@@ -317,6 +399,42 @@ func (dn *dataNode) Comments() comments {
 	return result
 }
 
+// ---------------------------------------------------------------------------
+// proxies
+// ---------------------------------------------------------------------------
+
+// addProxy creates a new dataNode and adds this proxy to it.
+func (dn *dataNode) addProxy(
+	proxyID string,
+	isolateValues bool,
+) *dataNode {
+	spawn := dn.spawnDescendant()
+
+	if len(proxyID) == 0 {
+		proxyID = makeNodeID()
+	}
+
+	// generate a proxy
+	proxy := &dataNode{}
+
+	// proxies maintain their own tree, so that we can walk the.
+	// proxy tree to update all proxies, instead of walking the
+	// full ancestry tree.
+	if dn.proxy != nil {
+		proxy = dn.proxy.spawnDescendant()
+	}
+
+	proxy.id = proxyID
+
+	if isolateValues {
+		proxy.isolationPrefix = proxyID
+	}
+
+	spawn.proxy = proxy
+
+	return spawn
+}
+
 // ---------------------------------------------------------------------------
 // ctx handling
 // ---------------------------------------------------------------------------
diff --git a/err.go b/err.go
index 7b03e63..96262a0 100644
--- a/err.go
+++ b/err.go
@@ -63,10 +63,7 @@ func newErr(
 		file:   file,
 		caller: getCaller(traceDepth + 1),
 		msg:    msg,
-		data: &dataNode{
-			id:     makeNodeID(),
-			values: m,
-		},
+		data:   &dataNode{values: m},
 	}
 }
 
@@ -106,10 +103,7 @@ func toStack(
 		file:   file,
 		caller: getCaller(traceDepth + 1),
 		stack:  stack,
-		data: &dataNode{
-			id:     makeNodeID(),
-			values: map[string]any{},
-		},
+		data:   &dataNode{values: map[string]any{}},
 	}
 }
 
diff --git a/err_fmt_test.go b/err_fmt_test.go
index c4ca1c9..e1c6b9d 100644
--- a/err_fmt_test.go
+++ b/err_fmt_test.go
@@ -1720,7 +1720,9 @@ func TestErrCore_String(t *testing.T) {
 			tc := test.core
 			if tc != nil {
 				if _, ok := tc.Values["clues_trace"]; !ok {
-					t.Error("expected core values to contain key [clues_trace]")
+					t.Errorf(
+						"expected core values to contain key [clues_trace]\ngot: %+v",
+						tc.Values)
 				}
 				delete(tc.Values, "clues_trace")
 			}