scripts: a lane that starts between two ticks of the live runner has spent nothing yet

packages/tui/test/live.rip

@@ -104,6 +104,17 @@ test "lanes in flight: a spinner, the name, a bar against the last run — by ti
     styledRow = cells.styled(view.ansi)[4]
     ok styledRow.startsWith(' «#22d3ee»⠹«» root (extended tier)  «#2cd6d4»█████████▋«dim»────'), "the bar is 24% of the way from cyan to green: #{styledRow}"
 
+test "a lane that starts between two ticks has spent nothing yet: its bar is empty and its colors are colors", ->
+  board MEMORY(), ({ view, tally, hear, lanes }) ->
+    hear 0, { type: 'plan' }, { type: 'finish', result: { lane: lanes[3], status: 'skip', ms: 0, why: lanes[3].skip, output: '' } }, { type: 'start', lane: lanes[0] }
+    # The lanes' clock moves on and a lane starts before the board's next
+    # tick, so the board's time is older than the lane's start.
+    tally.now = -> 8000
+    tally.hear { type: 'start', lane: lanes[1] }
+    frame = rows view.frame()
+    ok frame.some((row) -> row.includes('packages/sites')), frame.join '\n'
+    ok not /#[0-9a-f]{7}/.test(view.ansi), 'no color of seven digits'
+
 test "a lane past its last duration turns amber, and red past twice it; a first run sweeps a bar with nothing to fill it by", ->
   board MEMORY(), ({ view, hear, lanes }) ->
     hear 0, { type: 'plan' }, { type: 'start', lane: lanes[0] }

scripts/test-live.rip

@@ -50,6 +50,7 @@ hue =! (name) -> if screen.colors >= 256 then HUES[name] else NAMED[name]
 
 # A true color `t` of the way from one to the other.
 blend =! (from, to, t) ->
+  t = Math.min 1, Math.max(0, t)
   mix = (k) -> Math.round(parseInt(from.slice(k, k + 2), 16) * (1 - t) + parseInt(to.slice(k, k + 2), 16) * t)
   '#' + ((mix(k).toString(16).padStart 2, '0') for k in [1, 3, 5]).join ''
 
@@ -228,7 +229,7 @@ export class Tally
       return null unless weight
       total += weight
       done += weight if entry.result
-      done += Math.min(now - entry.at, weight) if entry.status is 'running'
+      done += Math.min(Math.max(0, now - entry.at), weight) if entry.status is 'running'
     if total then done / total else null
 
 # ── The memory of the last run ────────────────────────────────────────────────
@@ -376,7 +377,9 @@ export Board = component
 
   running ~=
     for entry in @tally.entries when entry.status is 'running'
-      spent = now - entry.at
+      # `now` is taken once a tick and a lane's start as it arrives, so a
+      # lane that starts between two ticks has spent nothing yet.
+      spent = Math.max 0, now - entry.at
       weight = @tally.estimate entry.lane.label
       counts = @tally.counted entry.lane.label
       record = @tally.memory.lanes[entry.lane.label]