send: stop the Max buttons from cancelling their own submit, show LNURL action errors

Choosing Max on the LNURL-pay page left the button spinning forever. Two
things combined:

The Max buttons set `loading` from their click handler. Svelte flushes
`disabled={loading}` to the DOM before the browser runs the button's
submit activation, and a disabled button submits nothing. Set loading
from the form's onsubmit instead, the way the Send button always did.

The /ln page never passed `form` into the Lnurlp and Lnurlw components,
so any action failure (pay, max or withdraw) rendered nothing and never
reset the spinner. Pass it through, and reset loading when a result
arrives.

Verified in headless Chrome against the dev stack: the bolt11 Max lands
on the fee view, and the LNURL Max surfaces the server's error and
re-enables the buttons.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

3 files changed, 21 insertions, 7 deletions

diff --git a/src/components/Lnurlp.svelte b/src/components/Lnurlp.svelte
index 2b715667..c1ae0c95 100644
--- a/src/components/Lnurlp.svelte
+++ b/src/components/Lnurlp.svelte
@@ -17,6 +17,8 @@
   let amount = $state(Math.round(minSendable / 1000)),
     loading = $state();
   let submit = () => (loading = true);
+  // An action result (an error, since success redirects) ends the wait
+  $effect(() => form && (loading = false));
 </script>
 
 <div class="container px-4 mt-20 max-w-xl mx-auto space-y-2">
@@ -60,12 +62,15 @@
 
     <div class="flex w-full gap-2">
       {#if max >= Math.round(minSendable / 1000)}
+        <!-- loading is set by the form's onsubmit, not here: flipping
+             `disabled` from a click handler lands in the DOM before the
+             browser's submit activation runs, and a disabled button submits
+             nothing (the page just sat on a spinner). -->
         <button
           type="submit"
           class="btn !w-auto grow"
           formaction="?/max"
-          disabled={loading}
-          onclick={submit}>Max ⚡️{s(max)}</button
+          disabled={loading}>Max ⚡️{s(max)}</button
         >
       {/if}
       <button bind:this={send} type="submit" class="btn btn-accent !w-auto grow">
diff --git a/src/routes/(app)/ln/[lnurl]/+page.svelte b/src/routes/(app)/ln/[lnurl]/+page.svelte
index 386df9d2..0f1b030f 100644
--- a/src/routes/(app)/ln/[lnurl]/+page.svelte
+++ b/src/routes/(app)/ln/[lnurl]/+page.svelte
@@ -1,12 +1,14 @@
 <script>
   import Lnurlp from "$comp/Lnurlp.svelte";
   import Lnurlw from "$comp/Lnurlw.svelte";
-  let { data } = $props();
+  let { data, form } = $props();
   let { tag } = data;
 </script>
 
+<!-- form carries the action result; without it a failed pay/max/withdraw
+     showed nothing and left the button spinning forever -->
 {#if tag === "payRequest"}
-  <Lnurlp {data} />
+  <Lnurlp {data} {form} />
 {:else if tag === "withdrawRequest"}
-  <Lnurlw {data} />
+  <Lnurlw {data} {form} />
 {/if}
diff --git a/src/routes/(app)/send/lightning/[payreq]/[...memo]/+page.svelte b/src/routes/(app)/send/lightning/[payreq]/[...memo]/+page.svelte
index c84e5d53..d3d9f757 100644
--- a/src/routes/(app)/send/lightning/[payreq]/[...memo]/+page.svelte
+++ b/src/routes/(app)/send/lightning/[payreq]/[...memo]/+page.svelte
@@ -174,7 +174,13 @@
       {/if}
     </form>
   {:else}
-    <form method="POST" action="?/setAmount" class="space-y-2" use:enhance>
+    <form
+      method="POST"
+      action="?/setAmount"
+      class="space-y-2"
+      use:enhance
+      onsubmit={submit}
+    >
       <input type="hidden" value={a} name="amount" />
       <input name="rate" value={$rate} type="hidden" />
 
@@ -187,12 +193,13 @@
       />
 
       <div class="flex justify-center gap-2">
+        <!-- no onclick: see Lnurlp.svelte — disabling from the click
+             handler cancels the submit; the form's onsubmit sets loading -->
         <button
           type="submit"
           class="btn !w-auto grow"
           formaction="?/max"
           disabled={loading}
-          onclick={submit}
         >
           {#if loading}
             <Spinner />