Compile release notes for v0.2.9

Author: pacrob

docs/release_notes.rst

@@ -3,6 +3,65 @@ Release Notes
 
 .. towncrier release notes start
 
+py-libp2p v0.2.9 (2025-07-09)
+-----------------------------
+
+Breaking Changes
+~~~~~~~~~~~~~~~~
+
+- Reordered the arguments to ``upgrade_security`` to place ``is_initiator`` before ``peer_id``, and made ``peer_id`` optional.
+  This allows the method to reflect the fact that peer identity is not required for inbound connections. (`#681 <https://github.com/libp2p/py-libp2p/issues/681>`__)
+
+
+Bugfixes
+~~~~~~~~
+
+- Add timeout wrappers in:
+  1. ``multiselect.py``: ``negotiate`` function
+  2. ``multiselect_client.py``: ``select_one_of`` , ``query_multistream_command`` functions
+  to prevent indefinite hangs when a remote peer does not respond. (`#696 <https://github.com/libp2p/py-libp2p/issues/696>`__)
+- Align stream creation logic with yamux specification (`#701 <https://github.com/libp2p/py-libp2p/issues/701>`__)
+- Fixed an issue in ``Pubsub`` where async validators were not handled reliably under concurrency. Now uses a safe aggregator list for consistent behavior. (`#702 <https://github.com/libp2p/py-libp2p/issues/702>`__)
+
+
+Features
+~~~~~~~~
+
+- Added support for ``Kademlia DHT`` in py-libp2p. (`#579 <https://github.com/libp2p/py-libp2p/issues/579>`__)
+- Limit concurrency in ``push_identify_to_peers`` to prevent resource congestion under high peer counts. (`#621 <https://github.com/libp2p/py-libp2p/issues/621>`__)
+- Store public key and peer ID in peerstore during handshake
+
+  Modified the InsecureTransport class to accept an optional peerstore parameter and updated the handshake process to store the received public key and peer ID in the peerstore when available.
+
+  Added test cases to verify:
+  1. The peerstore remains unchanged when handshake fails due to peer ID mismatch
+  2. The handshake correctly adds a public key to a peer ID that already exists in the peerstore but doesn't have a public key yet (`#631 <https://github.com/libp2p/py-libp2p/issues/631>`__)
+- Fixed several flow-control and concurrency issues in the ``YamuxStream`` class. Previously, stress-testing revealed that transferring data over ``DEFAULT_WINDOW_SIZE`` would break the stream due to inconsistent window update handling and lock management. The fixes include:
+
+  - Removed sending of window updates during writes to maintain correct flow-control.
+  - Added proper timeout handling when releasing and acquiring locks to prevent concurrency errors.
+  - Corrected the ``read`` function to properly handle window updates for both ``read_until_EOF`` and ``read_n_bytes``.
+  - Added event logging at ``send_window_updates`` and ``waiting_for_window_updates`` for better observability. (`#639 <https://github.com/libp2p/py-libp2p/issues/639>`__)
+- Added support for ``Multicast DNS`` in py-libp2p (`#649 <https://github.com/libp2p/py-libp2p/issues/649>`__)
+- Optimized pubsub publishing to send multiple topics in a single message instead of separate messages per topic. (`#685 <https://github.com/libp2p/py-libp2p/issues/685>`__)
+- Optimized pubsub message writing by implementing a write_msg() method that uses pre-allocated buffers and single write operations, improving performance by eliminating separate varint prefix encoding and write operations in FloodSub and GossipSub. (`#687 <https://github.com/libp2p/py-libp2p/issues/687>`__)
+- Added peer exchange and backoff logic as part of Gossipsub v1.1 upgrade (`#690 <https://github.com/libp2p/py-libp2p/issues/690>`__)
+
+
+Internal Changes - for py-libp2p Contributors
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- Added sparse connect utility function to pubsub test utilities for creating test networks with configurable connectivity. (`#679 <https://github.com/libp2p/py-libp2p/issues/679>`__)
+- Added comprehensive tests for pubsub connection utility functions to verify degree limits are enforced, excess peers are handled correctly, and edge cases (degree=0, negative values, empty lists) are managed gracefully. (`#707 <https://github.com/libp2p/py-libp2p/issues/707>`__)
+- Added extra tests for identify push concurrency cap under high peer load (`#708 <https://github.com/libp2p/py-libp2p/issues/708>`__)
+
+
+Miscellaneous Changes
+~~~~~~~~~~~~~~~~~~~~~
+
+- `#678 <https://github.com/libp2p/py-libp2p/issues/678>`__, `#684 <https://github.com/libp2p/py-libp2p/issues/684>`__
+
+
 py-libp2p v0.2.8 (2025-06-10)
 -----------------------------