Belts built after a tick reset join the network; pin tick in golden renders

A world started after a long session kept the old nextPowerBuild, so new
belts were never added until a reload. Treat a wait longer than 6 ticks as
stale. The golden test pins tick now that t45 animates belts from it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Cj2RPXdPykKMEz5BXXczsj

docs/agent-log.md

@@ -4,6 +4,18 @@ What agents have done, newest first. Add an entry for every piece of work: the d
 note or request it was for, what changed, the files touched, the tests run, and anything left
 open or not verified. Keep each entry short; the git history has the details.
 
+## 2026-10-29: new belts stood still until reload; golden test after t45 (Claude)
+
+- Owner bug: in a world started after a long session, belts built after loading never moved
+  (save and reload fixed them). The 6-tick power rebuild throttle (`nextPowerBuild`) survived
+  the tick reset of a new or loaded world, so rebuilds waited for the old tick count. Now a wait
+  longer than 6 ticks counts as stale. Not caused by t45; tests had hidden it with `nextPowerBuild=0`.
+- t45 animates belts from the tick (`transportClock`), so `t_gpu_golden.py` now pins `tick`
+  (1000 for pixel = old R.frame, 300 for smooth = old 5 s clock); all goldens match exactly again.
+- Files: sim/machine-tick, test/{t_basics.js,t_gpu_golden.py}, this log.
+- Tests: new t_basics check failed before the fix; all headless suites, t_stalls.py,
+  t_gpu_golden.py and play.py pass.
+
 ## 2026-10-29: t103 blow carried liquids without the Flask (Codex)
 
 - Removed only blow-side Flask gates, including Shift's HUD list; corrected the Flask hint.

src/sim/machine-tick.js

@@ -47,7 +47,8 @@ function fanBlow(mm, sat) {
 function machinesTick() {
   procBlocksTick();
   rackTick();
-  if (powerDirty && tick >= nextPowerBuild) { rebuildPower(); nextPowerBuild = tick + 6; }
+  // A new or loaded world restarts the tick count, so a wait longer than 6 ticks is stale.
+  if (powerDirty && (tick >= nextPowerBuild || nextPowerBuild > tick + 6)) { rebuildPower(); nextPowerBuild = tick + 6; }
   if (brokenMachines.length) {
     const ids = brokenMachines; brokenMachines = [];
     for (const id of ids) if (machines[id]) removeMachine(id, false, true);

test/t_basics.js

@@ -157,4 +157,10 @@ check('a save holding solid rock loads it as rubble with the same total', run(`(
   deserializeWorld(s.meta, s.buffers);
   return bag[BASALT] === 0 && bag[RBAS] === 1000 && bag[CLAY] === 0 && bag[LCLAY] === 200 && bag[MSLAG] === 7 && bagTotal === 1207;
 })()`));
+// A belt built in a new world joins the network even after a long earlier session (owner bug,
+// 2026-10-29: new belts stood still until the world was saved and loaded again).
+flatWorld(run, 256, 224, 208);
+run('RS = 7; nextPowerBuild = 500000; weather.next = 1e15; for (let bx = 12; bx < 40; bx++) placeBlock(BP_BELT, 1, bx, 32, true); setCell(127 * W + 60, SAND, 20, 0);');
+ticks(run, 60);
+check('a belt built after a tick reset carries its grains', run('mat[127 * W + 60] !== SAND && Array.from({ length: 100 }, (_, k) => mat[127 * W + 61 + k]).includes(SAND)'));
 done();

test/t_gpu_golden.py

@@ -39,7 +39,8 @@ with launch(viewport={'width': 640, 'height': 480}) as (_, pg, url):
                   SET.look=look;SET.zoom=zoom;SET.lighting='full';SET.lightEvery=1;SET.glow='low';
                   SM.t0=0; SM.surf=-1;
                   performance.now=()=>5000;resizeRender();bot.x=CAM[0]-bot.w/2;bot.y=CAM[1]-bot.h/2;
-                  snapCamera();R.frame=1000;drawWorld();
+                  // belts animate from the tick: pixel look by tick (was R.frame), smooth by tick/60 s (was the 5 s clock)
+                  snapCamera();R.frame=1000;tick=look==='smooth'?300:1000;drawWorld();
                 }""",[look,zoom])
                 raw=pg.evaluate("""() => {
                   const c=document.createElement('canvas');c.width=384;c.height=288;