Initial commit: snapshot of spesmilo/electrumx 2.0.0

Unmodified source tree of upstream commit 280cb339aa158e099eb936033eecd15719770651
("Merge pull request #389 from SomberNight/202607_release_2_0",
https://github.com/spesmilo/electrumx, release 2.0.0, 3 July 2026).

All Palladium-specific changes are in the commits that follow.

tests/server/test_notifications.py

@@ -0,0 +1,45 @@
+import pytest
+
+from electrumx.server.controller import Notifications
+
+
+@pytest.mark.asyncio
+async def test_simple_mempool():
+    n = Notifications()
+    notified = []
+    async def notify(*, touched_hashxs, touched_outpoints, height):
+        notified.append((height, touched_hashxs))
+    await n.start(5, notify)
+
+    mtouched = {b'a', b'b'}
+    btouched = {b'b', b'c'}
+    await n.on_mempool(touched_hashxs=mtouched, height=6, touched_outpoints=set())
+    assert notified == [(5, set())]
+    await n.on_block(touched_hashxs=btouched, height=6, touched_outpoints=set())
+    assert notified == [(5, set()), (6, set.union(mtouched, btouched))]
+
+
+@pytest.mark.asyncio
+async def test_enter_mempool_quick_blocks_2():
+    n = Notifications()
+    notified = []
+    async def notify(*, touched_hashxs, touched_outpoints, height):
+        notified.append((height, touched_hashxs))
+    await n.start(5, notify)
+
+    # Suppose a gets in block 6 and blocks 7,8 found right after and
+    # the block processor processes them together.
+    await n.on_mempool(touched_hashxs={b'a'}, height=5, touched_outpoints=set())
+    assert notified == [(5, set()), (5, {b'a'})]
+    # Mempool refreshes with daemon on block 6
+    await n.on_mempool(touched_hashxs={b'a'}, height=6, touched_outpoints=set())
+    assert notified == [(5, set()), (5, {b'a'})]
+    # Blocks 6, 7 processed together
+    await n.on_block(touched_hashxs={b'a', b'b'}, height=7, touched_outpoints=set())
+    assert notified == [(5, set()), (5, {b'a'})]
+    # Then block 8 processed
+    await n.on_block(touched_hashxs={b'c'}, height=8, touched_outpoints=set())
+    assert notified == [(5, set()), (5, {b'a'})]
+    # Now mempool refreshes
+    await n.on_mempool(touched_hashxs=set(), height=8, touched_outpoints=set())
+    assert notified == [(5, set()), (5, {b'a'}), (8, {b'a', b'b', b'c'})]