Keep callback renders working after repeated updates

[Seigiard]

For non-engineers.

• Problem: A page could stop refreshing after two updates.
• Impact: New data could arrive while users still saw the old list or text until they reloaded the page.
• What was done: Repeated updates now keep the rendering state that owns the displayed content.
• What you will notice: New list entries and text updates appear without a page reload.

Why

Fix the third and subsequent render(container, callback) calls for an unchanged template so repeated updates remain usable.

Watch out for

Door: two-way. A plain revert restores the broken repeated-render path; this change has no persistent data effects.

• The browser regression follows the existing HTML tests and must be opened against rebuilt bundles; the current Node test command does not run browser tests.

Shape of the change

The second render updates the initialized cached Hole, but previously stored the fresh callback result instead; the third render then interpreted raw values as prepared update entries.

-    else known[1].update(hole);
+    else {
+      known[1].update(hole);
+      hole = known[1];
+    }
     rendered.set(where, [scope, hole]);

test/render.html checks four text renders, a list changing from empty to restored to prepended entries, and DOM node identity. Serve the repository root and open /test/render.html for the development bundle or /test/render.html?prod for production.

Evidence

• Before: The browser regression failed in headless Chromium against both unpatched bundles on the third text render: Cannot assign to read only property '2' of string 'second'. In a desktop WebKit application, the list update failed with Node.insertBefore receiving a non-Node value.
• After: Both rebuilt bundles report PASS: repeated text and list renders for the same browser regression.
• Visuals: Behavioural DOM assertions are the evidence; no separate screenshots.

npm run test:all and npm run types pass. Development and production bundles were rebuilt with Rollup and tested in Chromium. CI has not run for this branch yet.