diff --git a/baremetal/shell/read.mu b/baremetal/shell/read.mu
index e619affd..24d5df13 100644
--- a/baremetal/shell/read.mu
+++ b/baremetal/shell/read.mu
@@ -122,6 +122,7 @@ fn next-number-token in: (addr gap-buffer), out: (addr stream byte), trace: (add
     compare digit?, 0/false
     break-if-!=
     error trace, "invalid number"
+    return
   }
   var g/eax: grapheme <- read-from-gap-buffer in
   write-grapheme out, g
diff --git a/baremetal/shell/sandbox.mu b/baremetal/shell/sandbox.mu
index a766bc4d..08b76c3a 100644
--- a/baremetal/shell/sandbox.mu
+++ b/baremetal/shell/sandbox.mu
@@ -59,27 +59,25 @@ fn render-sandbox screen: (addr screen), _self: (addr sandbox), _x: int, _y: int
   var x/eax: int <- copy _x
   var y/ecx: int <- copy _y
   x, y <- render-gap-buffer-wrapping-right-then-down screen, data, x, y, 0x20/xmax, 0x20/ymax, x, y, 1/show-cursor
-  {
-    var value-ah/eax: (addr handle stream byte) <- get self, value
-    var value/eax: (addr stream byte) <- lookup *value-ah
-    var done?/eax: boolean <- stream-empty? value
-    compare done?, 0/false
-    break-if-=
-    return
-  }
   y <- increment
   # trace
   var trace-ah/eax: (addr handle trace) <- get self, trace
   var _trace/eax: (addr trace) <- lookup *trace-ah
   var trace/edx: (addr trace) <- copy _trace
   y <- render-trace screen, trace, _x, y, 0x20/xmax, 0x20/ymax
-  y <- increment
   # value
+  var value-ah/eax: (addr handle stream byte) <- get self, value
+  var _value/eax: (addr stream byte) <- lookup *value-ah
+  var value/esi: (addr stream byte) <- copy _value
+  var done?/eax: boolean <- stream-empty? value
+  compare done?, 0/false
+  {
+    break-if-=
+    return
+  }
   var x/eax: int <- copy 0
   x, y <- draw-text-wrapping-right-then-down screen, "=> ", _x, y, 0x20/xmax, 0x20/ymax, _x, y, 7/fg, 0/bg
   var x2/edx: int <- copy x
-  var value-ah/eax: (addr handle stream byte) <- get self, value
-  var value/eax: (addr stream byte) <- lookup *value-ah
   var dummy/eax: int <- draw-stream-rightward screen, value, x2, 0x30/xmax, y, 7/fg=grey, 0/bg
 }
 
diff --git a/baremetal/shell/trace.mu b/baremetal/shell/trace.mu
index 90a2a844..4c699a08 100644
--- a/baremetal/shell/trace.mu
+++ b/baremetal/shell/trace.mu
@@ -30,6 +30,7 @@ fn has-errors? _self: (addr trace) -> _/eax: boolean {
   var trace-ah/eax: (addr handle stream trace-line) <- get self, data
   var _trace/eax: (addr stream trace-line) <- lookup *trace-ah
   var trace/esi: (addr stream trace-line) <- copy _trace
+  rewind-stream trace
   {
     var done?/eax: boolean <- stream-empty? trace
     compare done?, 0/false
@@ -92,8 +93,167 @@ fn trace-higher _self: (addr trace) {
 }
 
 fn render-trace screen: (addr screen), _self: (addr trace), xmin: int, ymin: int, xmax: int, ymax: int -> _/ecx: int {
-  var x/eax: int <- copy xmin
+  var already-hiding-lines?/ebx: boolean <- copy 0/false
   var y/ecx: int <- copy ymin
-  x, y <- draw-text-wrapping-right-then-down screen, "...", xmin, ymin, xmax, ymax, x, y, 9/fg=trace, 0/bg
+  var self/eax: (addr trace) <- copy _self
+  var trace-ah/eax: (addr handle stream trace-line) <- get self, data
+  var _trace/eax: (addr stream trace-line) <- lookup *trace-ah
+  var trace/esi: (addr stream trace-line) <- copy _trace
+  rewind-stream trace
+  $render-trace:loop: {
+    var done?/eax: boolean <- stream-empty? trace
+    compare done?, 0/false
+    break-if-!=
+    var curr-storage: trace-line
+    var curr/edx: (addr trace-line) <- address curr-storage
+    read-from-stream trace, curr
+    var curr-label-ah/eax: (addr handle array byte) <- get curr, label
+    var curr-label/eax: (addr array byte) <- lookup *curr-label-ah
+    # always display errors
+    var is-error?/eax: boolean <- string-equal? curr-label, "error"
+    {
+      compare is-error?, 0/false
+      break-if-=
+      var curr-data-ah/eax: (addr handle array byte) <- get curr, data
+      var _curr-data/eax: (addr array byte) <- lookup *curr-data-ah
+      var curr-data/edx: (addr array byte) <- copy _curr-data
+      var x/eax: int <- copy xmin
+      x, y <- draw-text-wrapping-right-then-down screen, curr-data, xmin, ymin, xmax, ymax, x, y, 0xc/fg=trace-error, 0/bg
+      y <- increment
+      already-hiding-lines? <- copy 0/false
+      loop $render-trace:loop
+    }
+    # otherwise ignore the rest
+    compare already-hiding-lines?, 0/false
+    {
+      break-if-!=
+      var x/eax: int <- copy xmin
+      x, y <- draw-text-wrapping-right-then-down screen, "...", xmin, ymin, xmax, ymax, x, y, 9/fg=trace, 0/bg
+      y <- increment
+    }
+    loop
+  }
   return y
 }
+
+fn test-render-trace-empty {
+  var t-storage: trace
+  var t/esi: (addr trace) <- address t-storage
+  initialize-trace t, 0x10
+  # setup: screen
+  var screen-on-stack: screen
+  var screen/edi: (addr screen) <- address screen-on-stack
+  initialize-screen screen, 5, 4
+  #
+  var y/ecx: int <- render-trace screen, t, 0/xmin, 0/ymin, 5/xmax, 4/ymax
+  #
+  check-ints-equal y, 0, "F - test-render-trace-empty/cursor"
+  check-screen-row screen, 0/y, "    ", "F - test-render-trace-empty"
+}
+
+fn test-render-trace-collapsed-by-default {
+  var t-storage: trace
+  var t/esi: (addr trace) <- address t-storage
+  initialize-trace t, 0x10
+  var contents-storage: (stream byte 0x10)
+  var contents/ecx: (addr stream byte) <- address contents-storage
+  write contents, "data"
+  trace t, "l", contents
+  # setup: screen
+  var screen-on-stack: screen
+  var screen/edi: (addr screen) <- address screen-on-stack
+  initialize-screen screen, 5, 4
+  #
+  var y/ecx: int <- render-trace screen, t, 0/xmin, 0/ymin, 5/xmax, 4/ymax
+  #
+  check-ints-equal y, 1, "F - test-render-trace-collapsed-by-default/cursor"
+  check-screen-row screen, 0/y, "... ", "F - test-render-trace-collapsed-by-default"
+}
+
+fn test-render-trace-error {
+  var t-storage: trace
+  var t/esi: (addr trace) <- address t-storage
+  initialize-trace t, 0x10
+  error t, "error"
+  # setup: screen
+  var screen-on-stack: screen
+  var screen/edi: (addr screen) <- address screen-on-stack
+  initialize-screen screen, 0xa, 4
+  #
+  var y/ecx: int <- render-trace screen, t, 0/xmin, 0/ymin, 0xa/xmax, 4/ymax
+  #
+  check-ints-equal y, 1, "F - test-render-trace-error/cursor"
+  check-screen-row screen, 0/y, "error", "F - test-render-trace-error"
+}
+
+fn test-render-trace-error-at-start {
+  var t-storage: trace
+  var t/esi: (addr trace) <- address t-storage
+  initialize-trace t, 0x10
+  # line 1
+  error t, "error"
+  # line 2
+  var contents-storage: (stream byte 0x10)
+  var contents/ecx: (addr stream byte) <- address contents-storage
+  write contents, "data"
+  trace t, "l", contents
+  # setup: screen
+  var screen-on-stack: screen
+  var screen/edi: (addr screen) <- address screen-on-stack
+  initialize-screen screen, 0xa, 4
+  #
+  var y/ecx: int <- render-trace screen, t, 0/xmin, 0/ymin, 0xa/xmax, 4/ymax
+  #
+  check-ints-equal y, 2, "F - test-render-trace-error-at-start/cursor"
+  check-screen-row screen, 0/y, "error", "F - test-render-trace-error-at-start/0"
+  check-screen-row screen, 1/y, "...  ", "F - test-render-trace-error-at-start/1"
+}
+
+fn test-render-trace-error-at-end {
+  var t-storage: trace
+  var t/esi: (addr trace) <- address t-storage
+  initialize-trace t, 0x10
+  # line 1
+  var contents-storage: (stream byte 0x10)
+  var contents/ecx: (addr stream byte) <- address contents-storage
+  write contents, "data"
+  trace t, "l", contents
+  # line 2
+  error t, "error"
+  # setup: screen
+  var screen-on-stack: screen
+  var screen/edi: (addr screen) <- address screen-on-stack
+  initialize-screen screen, 0xa, 4
+  #
+  var y/ecx: int <- render-trace screen, t, 0/xmin, 0/ymin, 0xa/xmax, 4/ymax
+  #
+  check-ints-equal y, 2, "F - test-render-trace-error-at-end/cursor"
+  check-screen-row screen, 0/y, "...  ", "F - test-render-trace-error-at-end/0"
+  check-screen-row screen, 1/y, "error", "F - test-render-trace-error-at-end/1"
+}
+
+fn test-render-trace-error-in-the-middle {
+  var t-storage: trace
+  var t/esi: (addr trace) <- address t-storage
+  initialize-trace t, 0x10
+  # line 1
+  var contents-storage: (stream byte 0x10)
+  var contents/ecx: (addr stream byte) <- address contents-storage
+  write contents, "data"
+  trace t, "l", contents
+  # line 2
+  error t, "error"
+  # line 3
+  trace t, "l", contents
+  # setup: screen
+  var screen-on-stack: screen
+  var screen/edi: (addr screen) <- address screen-on-stack
+  initialize-screen screen, 0xa, 4
+  #
+  var y/ecx: int <- render-trace screen, t, 0/xmin, 0/ymin, 0xa/xmax, 4/ymax
+  #
+  check-ints-equal y, 3, "F - test-render-trace-error-in-the-middle/cursor"
+  check-screen-row screen, 0/y, "...  ", "F - test-render-trace-error-in-the-middle/0"
+  check-screen-row screen, 1/y, "error", "F - test-render-trace-error-in-the-middle/1"
+  check-screen-row screen, 2/y, "...  ", "F - test-render-trace-error-in-the-middle/2"
+}