Isolate execution observations and preserve injected error categories

internal/observation/recorder.go

@@ -191,6 +191,24 @@ func (r *Recorder) deliver(event domain.ExecutionEvent) {
 
 type contextKey struct{}
 
+// WithoutExecutionState starts a public operation without inheriting another
+// invocation's recorder or prepared-claim sink. Other context values and all
+// cancellation/deadline behavior remain with the caller's context.
+func WithoutExecutionState(ctx context.Context) context.Context {
+	return executionBoundary{Context: ctx}
+}
+
+type executionBoundary struct{ context.Context }
+
+func (c executionBoundary) Value(key any) any {
+	switch key.(type) {
+	case contextKey, claimSinkKey:
+		return nil
+	default:
+		return c.Context.Value(key)
+	}
+}
+
 // WithRecorder carries one invocation's recorder through internal client calls.
 func WithRecorder(ctx context.Context, recorder *Recorder) context.Context {
 	return context.WithValue(ctx, contextKey{}, recorder)

internal/observation/recorder_test.go

@@ -2,6 +2,7 @@ package observation
 
 import (
 	"context"
+	"errors"
 	"reflect"
 	"testing"
 	"time"
@@ -9,6 +10,35 @@ import (
 	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
 )
 
+func TestExecutionBoundaryPreservesCallerContext(t *testing.T) {
+	type callerKey struct{}
+	parent, stop := context.WithTimeout(context.WithValue(context.Background(), callerKey{}, "caller"), time.Minute)
+	defer stop()
+	parent, cancel := context.WithCancelCause(parent)
+	defer cancel(nil)
+	recorder := newRecorder("outer", time.Now, nil)
+	sink := recorder
+	parent = WithClaimSink(WithRecorder(parent, recorder), &sink)
+	child := WithoutExecutionState(parent)
+	if FromContext(child) != nil || FromContext(parent) != recorder {
+		t.Fatal("execution boundary did not isolate recorder state")
+	}
+	RegisterClaim(child, nil)
+	if sink != recorder {
+		t.Fatal("execution boundary retained the parent claim sink")
+	}
+	wantDeadline, _ := parent.Deadline()
+	gotDeadline, ok := child.Deadline()
+	if !ok || gotDeadline != wantDeadline || child.Value(callerKey{}) != "caller" || child.Done() != parent.Done() {
+		t.Fatal("execution boundary changed caller context")
+	}
+	cause := errors.New("caller canceled")
+	cancel(cause)
+	if !errors.Is(child.Err(), context.Canceled) || context.Cause(child) != cause {
+		t.Fatal("execution boundary lost cancellation or its cause")
+	}
+}
+
 func TestRecorderAccountsDispatchedAttemptsAndReportedUsage(t *testing.T) {
 	start := time.Date(2026, 9, 23, 12, 0, 0, 0, time.UTC)
 	tick := 0