Fix deadlock in cmdio tea program queueing

libs/cmdio/io.go

@@ -156,8 +156,14 @@ func (c *cmdIO) acquireTeaProgram(p *tea.Program) {
 	defer c.teaMu.Unlock()
 
 	// Wait for existing program to finish
-	if c.teaDone != nil {
-		<-c.teaDone
+	// Receive with teaMu released: releaseTeaProgram locks teaMu to close
+	// teaDone, so waiting while holding it would deadlock. Loop because another
+	// acquirer may register a new program before the lock is reacquired.
+	for c.teaDone != nil {
+		done := c.teaDone
+		c.teaMu.Unlock()
+		<-done
+		c.teaMu.Lock()
 	}
 
 	// Register new program

libs/cmdio/io_test.go

@@ -0,0 +1,36 @@
+package cmdio
+
+import (
+	"testing"
+	"time"
+)
+
+func TestAcquireTeaProgramWaitsForRelease(t *testing.T) {
+	c := &cmdIO{}
+	// acquireTeaProgram only stores the pointer, so a nil program suffices.
+	c.acquireTeaProgram(nil)
+
+	acquired := make(chan struct{})
+	go func() {
+		c.acquireTeaProgram(nil)
+		close(acquired)
+	}()
+
+	select {
+	case <-acquired:
+		t.Fatal("second acquireTeaProgram returned while the first program was still active")
+	case <-time.After(50 * time.Millisecond):
+	}
+
+	// Release on a goroutine so a regressed deadlock fails the timeout below
+	// instead of hanging the test.
+	go c.releaseTeaProgram()
+
+	select {
+	case <-acquired:
+	case <-time.After(5 * time.Second):
+		t.Fatal("second acquireTeaProgram did not return after the first program was released")
+	}
+
+	c.releaseTeaProgram()
+}