fix(hub): the transfers row exists from the click

Clicking Download produced nothing — no row, no icon, no panel — for as long as
it took to open somewhere to write, and then several rows at once. The streamed
path waits for the worker twice; a Save As dialog waits for a person. The row
was created after that, so the slowest part of a download happened with nothing
on screen to say it had begun.

The store gains a `prepare` step, distinct from `run`, and the order is now:
row, then target, then slot.

That last part is why the obvious fix was wrong. Taking the slot first would let
the row appear immediately, and it was tried this morning: a granted slot has to
be taken up within the node's deadline, opening a target can outlast it, and
three downloads became one. (The diagnosis at the time blamed that ordering for
revocations which were in fact a missing `touch()` call — the revert was right
for the wrong reason.) `makeLease` is called after `prepare` succeeds, never
before.

Three behaviours fall out, each with a test:

  - a dismissed dialog leaves nothing behind. `prepare` returning false drops
    the row: nothing started, so nothing should remain on screen to explain it;
  - the row takes the name the file was actually saved under, once known;
  - a refusal above the memory ceiling fails the row that is already there,
    rather than creating one to kill it.

`preparing` counts as live everywhere — badge, cancel, clearFinished, and
`_busy`, since closing a transport under a preparing transfer strands it exactly
as under a queued one. Six places asked "is this finished?" and were drifting
apart; there is one definition now.

Two mistakes in the tests, worth the note: one counted positions in an output
array by hand and was one out, which reads exactly like a failing assertion
about the code — the values are tagged now, not indexed. And
test_zip_size_limit.py's stub did not run `prepare`, so it no longer reached the
size check the file is about; it now behaves like the real store.

819 hub, 1169 node, 0 failed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HCGdheDLxGReuKHga3BtST

1 files changed, 19 insertions, 4 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/app.js b/packages/meshbay-hub/src/meshbay_hub/static/app.js
index ff066cf..6f4bb92 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/app.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/app.js
@@ -157,9 +157,11 @@ function TransferWidget() {
   }, [open]);
 
   const running = items.filter(i => i.status === 'running');
-  const waiting = items.filter(i => i.status === 'queued');
+  const waiting = items.filter(
+    i => i.status === 'queued' || i.status === 'preparing');
   const finished = items.filter(
-    i => i.status !== 'running' && i.status !== 'queued');
+    i => i.status !== 'running' && i.status !== 'queued'
+      && i.status !== 'preparing');
   const active = running.length + waiting.length;
 
   // Grouped, and in this order: what is moving, what is waiting, what is over.
@@ -240,7 +242,8 @@ function TransferRow({ it }) {
           ? html`<a class="transfer-name" href="#" title=${it.name}
               onClick=${(e) => { e.preventDefault(); transfers.open(it.id); }}>${it.name}</a>`
           : html`<span class="transfer-name" title=${it.name}>${it.name}</span>`}
-        ${(it.status === 'running' || it.status === 'queued') && html`
+        ${(it.status === 'running' || it.status === 'queued'
+           || it.status === 'preparing') && html`
           <button class="transfer-cancel"
             aria-label=${t('transfers.cancel_one', { name: it.name })}
             title=${t('transfers.cancel')}
@@ -249,7 +252,19 @@ function TransferRow({ it }) {
           </button>
         `}
       </div>
-      ${it.status === 'queued'
+      ${it.status === 'preparing'
+        ? html`
+          ${/* Not a progress bar at 0%: nothing is wrong and nothing is
+                stalled, the download is still finding somewhere to write. The
+                row exists from the click precisely so this state is visible
+                instead of being an empty panel. */''}
+          <div class="dl-progress dl-waiting"></div>
+          <div class="transfer-meta">
+            <span>${t('transfers.preparing')}</span>
+            <span>${formatSize(it.total)}</span>
+          </div>
+        `
+        : it.status === 'queued'
         ? html`
           <div class="dl-progress dl-waiting"></div>
           <div class="transfer-meta">