diff --git a/cmd/cue/cmd/testdata/script/cmd_issue4195.txtar b/cmd/cue/cmd/testdata/script/cmd_issue4195.txtar
new file mode 100644
index 000000000..575f6c3f7
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/cmd_issue4195.txtar
@@ -0,0 +1,49 @@
+# Regression test for https://github.com/cue-lang/cue/issues/4195
+#
+# When two tasks run concurrently and a comprehension over one task's
+# result contains conditionals depending on the other task's result,
+# the flow engine could discover "phantom" tasks from both conditional
+# branches during an intermediate evaluation. These phantom tasks were
+# never pruned and would be dispatched later, failing because their
+# conditional branch no longer existed in the configuration.
+
+exec cue cmd main
+
+-- input/foo.json --
+-- input/bar.json --
+-- output/foo.json --
+-- cue.mod/module.cue --
+module: "test.example"
+language: version: "v0.9.0"
+-- main_tool.cue --
+package repro
+
+import (
+	"tool/cli"
+	"tool/exec"
+	"tool/file"
+	"list"
+	"path"
+)
+
+command: main: {
+	inputs: file.Glob & {glob: "input/*.json"}
+	// Delay "outputs" so that "inputs" is always processed first,
+	// causing initTasks to discover phantom conditional tasks.
+	delay:   exec.Run & {cmd: ["testcmd", "sleep_and_print", "50ms"]}
+	outputs: file.Glob & {glob: "output/*.json", $after: delay}
+
+	for _, inputpath in inputs.files {
+		(inputpath): {
+			_output: path.Join(["output", path.Base(inputpath)], path.Unix)
+			_done:   list.Contains(outputs.files, _output)
+
+			if _done {
+				print: cli.Print & {text: "\(inputpath) already in outputs"}
+			}
+			if !_done {
+				work: cli.Print & {text: "\(inputpath) not yet done"}
+			}
+		}
+	}
+}
diff --git a/tools/flow/run.go b/tools/flow/run.go
index 7ab53f89c..6b936ae7d 100644
--- a/tools/flow/run.go
+++ b/tools/flow/run.go
@@ -67,11 +67,18 @@ func (c *Controller) runLoop() {
 				waiting = true
 
 			case Ready:
-				running = true
-
 				t.state = Running
 				c.updateTaskValue(t)
 
+				// If the task's path no longer resolves in the configuration
+				// (e.g. because a conditional guard was eliminated as the
+				// config became more concrete), skip this task.
+				if !t.v.Exists() {
+					t.state = Terminated
+					continue
+				}
+
+				running = true
 				t.ctxt = eval.NewContext(value.ToInternal(t.v))
 
 				go func(t *Task) {