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5 Commits

Author SHA1 Message Date
ddidderr ce51d92df0 refactor(peer): tighten listener-addr handshake invariant
Follow-up hardening for 348a02c, where `listen_addr` was added to Hello and
HelloAck as `Option<SocketAddr>`. Code review surfaced three concrete problems
that the previous commit left open:

1. Cold-start asymmetry. Discovery and the QUIC/mDNS advertiser are spawned
   concurrently. If discovery saw a cached peer advertisement before our own
   advertiser had written `ctx.local_peer_addr`, our outbound Hello carried
   `listen_addr: None`. The receiver's `peer_record_addr` then returned `None`
   and silently dropped the Hello while we still recorded their HelloAck, so
   peer A learned about peer B but B never learned about A until a later
   handshake happened to win the race.

2. Duplicate game-list pipeline. The previous commit added
   `refresh_peer_games`, which post-handshake issued a `ListGames` to fetch
   `peer.games`. The library-sync path (`LibrarySnapshot`) already populates
   the same field. Both could race on first contact and overwrite each other.
   Worse, `refresh_peer_games` was misnamed: a `peer_game_count > 0` guard
   turned it into a fetch-once-then-no-op helper, while
   `handle_library_summary` independently re-triggered a full handshake when
   `previous_count == 0` was observed, producing a redundant ping-pong on
   every first contact.

3. Argument explosion. `perform_handshake_with_peer`, `spawn_library_resync`,
   and `after_peer_library_recorded` had grown to 6-8 individual parameters
   and acquired `#[allow(clippy::too_many_arguments)]` opt-outs. Every caller
   was destructuring the same fields out of `Ctx`/`PeerCtx`.

Changes (all in one commit because they jointly enforce the same invariant:
"a peer is only ever recorded by its listener address, and the local
listener address must exist before we participate in the protocol"):

- `Hello.listen_addr` and `HelloAck.listen_addr` are now `SocketAddr`, not
  `Option<SocketAddr>`. Wire-incompatible, but PROTOCOL_VERSION already moved
  to 3 in 348a02c so no additional version bump is needed.
- `required_listen_addr` reads `ctx.local_peer_addr` and returns an
  `eyre::Result`; `build_hello_from_state` and `build_hello_ack` both call
  it, so an outbound or inbound Hello can no longer be constructed before
  the local QUIC listener is bound. The inbound path maps this into a
  `Response::InternalPeerError` so the remote peer fails cleanly instead of
  seeing a malformed HelloAck.
- `run_peer_discovery` blocks on `wait_for_local_peer_addr` (25 ms poll,
  shutdown-aware) before subscribing to the mDNS browser. This closes the
  cold-start race for outbound handshakes at the source.
- `refresh_peer_games`, `request_game_list_from_peer`, and the
  `previous_count == 0` re-handshake trigger are removed. The post-handshake
  flow now relies solely on `LibrarySummary`/`LibrarySnapshot`/`LibraryDelta`
  for peer-library state; `ListGames` survives only for the
  `request_game_details_*` paths that fetch per-game file descriptions on
  demand.
- New `HandshakeCtx` (with `from_ctx` and `from_peer_ctx` constructors)
  replaces the long argument lists. All `too_many_arguments` allow-attrs in
  `handshake.rs` are gone, and call sites in `handlers.rs`, `discovery.rs`,
  and `stream.rs` collapse to a single clone.
- `handle_library_delta` no longer acquires a read lock on the apply path:
  the `peer_addr` lookup moved into the `else` resync branch where it is
  actually needed.
- `accept_inbound_hello`'s `remote_addr` parameter is renamed to
  `transport_addr`. It is now used only for warn-log formatting, and the
  new name signals that this is the ephemeral QUIC source port, never the
  authoritative listener address that gets recorded.

User-visible effect: on cold start, peers can no longer end up with an
asymmetric view of each other ("A sees B but B never sees A"). First-contact
library sync now does one handshake plus one snapshot/delta exchange instead
of the previous handshake + ListGames + redundant follow-up handshake. The
direct-connect CLI path (`handle_connect_peer_command`) now fails fast with
"local peer listener address is not ready" if invoked before the QUIC server
has bound; this is intentional - the previous behaviour would have sent a
Hello that the receiver had to silently discard.

Test Plan:
- just fmt
- just clippy
- just test (80 peer + 3 cli + 5 tauri tests pass)
- just build
- Manual: bring up `just peer-cli-alpha`/`bravo`/`charlie`, confirm symmetric
  peer discovery and that games show up on every side after one library
  digest cycle, with no duplicated ListGames traffic in trace logs.

Refs: Review feedback on commit 348a02c (listener-address handshake fix).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-18 18:21:19 +02:00
ddidderr 348a02c35f fix(peer): record listener addresses during handshakes
Peers discovered over mDNS could still attribute later library sync traffic to
temporary QUIC source ports. In a real GUI LAN run this made Host B try to
push its library to Host A's outbound port instead of Host A's advertised
listener, so Host A discovered the peer but never saw its games.

Carry the stable listener address in Hello and HelloAck, and key library sync
messages by peer_id instead of inferring identity from the transport source
address. The handshake path now explicitly refreshes an empty peer library from
the known listener address, matching the reliability of the direct-connect CLI
path without overwriting richer snapshot state when it already arrived.

This changes the current wire protocol, so PROTOCOL_VERSION is bumped to 3 and
all peers must be rebuilt together. The architecture note now documents that
listener addresses come from mDNS or Hello/HelloAck, never from ephemeral QUIC
source ports.

Test Plan:
- just fmt
- just test
- just clippy
- just build
- git diff --check

Refs: Local Linux/Win11 GUI LAN test logs from 2026-05-18.
2026-05-18 17:27:15 +02:00
ddidderr e711cf3454 fix(peer): settle current-protocol local state cleanup
The follow-up backlog had drifted into three settled peer/runtime issues: the
legacy game-list fallback contradicted the one-wire-version policy, the Tauri
shell still re-derived local install state from disk after peer snapshots, and
`Availability::Downloading` existed even though active operations are already
reported through a separate operation table.

Remove the legacy `AnnounceGames` request and fallback service. Discovery now
ignores peers that do not advertise the current protocol and a peer id, and
library changes are sent through the current delta path only. This keeps the
runtime aligned with the documented current-build-only interoperability model.

Make peer `LocalGamesUpdated` snapshots authoritative for local fields in the
Tauri database. The GUI-side catalog still owns static metadata such as names,
sizes, and descriptions, but downloaded, installed, local version, and
availability now come from the peer runtime instead of a second whole-library
filesystem scan. Snapshot reconciliation also pins the missing-begin and
missing-finish lifecycle cases in tests.

Collapse availability back to the settled `Ready` and `LocalOnly` states.
Aggregation now counts only `Ready` peers as download sources, and the frontend
no longer carries a dead `Downloading` enum value.

The core peer also exposes the small non-GUI hooks needed by scripted callers:
startup options for state and mDNS, a local-ready event, direct connection, peer
snapshots, and an explicit post-download install policy. Those hooks reuse the
same current protocol path and do not add compatibility shims.

Test Plan:
- `git diff --check`
- `just fmt`
- `just clippy`
- `just test`

Refs: BACKLOG.md, FINDINGS.md, IMPL_DECISIONS.md
2026-05-16 18:32:24 +02:00
ddidderr 2bbd2ac869 refactor(peer): adopt structured concurrency with supervised shutdown
Replace the detached tokio::spawn pattern in the peer runtime with a
supervised model built on tokio_util's CancellationToken and TaskTracker.
Long-lived services and child tasks now have an explicit parent, a
cancellation path, and a join point. Tauri can request a clean shutdown
on app exit instead of leaking work into process termination.

Background
~~~~~~~~~~

start_peer() previously returned only a command sender. The four startup
services (QUIC server, mDNS discovery, peer liveness, local library
monitor) and their child tasks (ping workers, handshake jobs, download
workers, announcement fan-outs, connection/stream handlers) were spawned
with raw tokio::spawn and detached. Closing the command channel sent
Goodbye notifications but did not stop those services. The mDNS blocking
worker had no cancellation path at all. Active downloads were stored as
JoinHandle<()> and force-aborted, which could interrupt file writes
mid-chunk.

Supervisor
~~~~~~~~~~

The runtime now owns a CancellationToken and a TaskTracker, threaded
through Ctx and PeerCtx. Each long-lived service is spawned through a
small supervisor (spawn_supervised_service) that wraps the service in
catch_unwind and enforces an explicit SupervisionPolicy:

  QuicServer:    Required     (fatal; cancels the runtime if it dies)
  Discovery:     Restart(5s)  (matches the prior self-restart loop)
  Liveness:      Restart(5s)
  LocalMonitor:  BestEffort   (logs and exits, no restart)

A Required failure emits a new RuntimeFailed { component, error } event
to the UI and cancels the runtime; the command loop and goodbye
notifications still run to completion. The Tauri layer forwards the
event as "peer-runtime-failed" so a future UI can surface it.

mDNS cancellation
~~~~~~~~~~~~~~~~~

MdnsBrowser previously blocked on receiver.recv() forever. It now
exposes next_service_timeout(Duration) returning an MdnsServicePoll
enum (Service/Timeout/Closed) via recv_timeout(). The discovery worker
polls at 250ms and checks the shutdown flag between ticks, so
cancellation reaches the blocking thread within one poll interval
instead of waiting for the next mDNS event.

Downloads
~~~~~~~~~

active_downloads is now HashMap<String, CancellationToken>. Each
download gets a child token of the runtime shutdown, checked at chunk
and peer-attempt boundaries (never inside file writes). When all peers
with a game disappear, liveness cancels the token and emits
DownloadGameFilesAllPeersGone; the download exits Ok(()) without
emitting a duplicate Failed event.

DownloadStateGuard (context.rs) is held inside the download task and
clears downloading_games + active_downloads on Drop, covering the happy
path, error returns, cancellation, and task abort. Drop falls back to
spawning the cleanup if write-lock contention prevents try_write.

Public API and Tauri integration
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

start_peer() now returns PeerRuntimeHandle exposing:

  fn sender(&self) -> UnboundedSender<PeerCommand>
  fn shutdown(&self)
  async fn wait_stopped(&mut self)

The Tauri layer stores the handle in managed state and switches its
main loop from .run(ctx) to .build(ctx).run(|h, e| ...). On
RunEvent::Exit it calls handle.shutdown() and blocks up to 2s on
wait_stopped(), giving services time to cancel and Goodbye packets time
to flush over a healthy LAN while staying short enough not to delay
process exit noticeably on a dead network.

The command loop distinguishes graceful shutdown from unexpected
channel closure: if recv() returns None and shutdown.is_cancelled() is
set, the loop returns Ok(()) silently. Only an unexpected close (no
cancellation observed) still emits RuntimeFailed. This avoids a
spurious failure event on every normal app close.

User-visible behavior changes
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Closing the app no longer leaks services into process termination;
  Goodbye notifications are reliably attempted before exit.
- Downloads cancel cleanly (between chunks) instead of force-aborting
  mid-write.
- A new "peer-runtime-failed" Tauri event fires when a Required service
  cannot recover. No frontend handler exists yet — that is a follow-up.

Tradeoffs
~~~~~~~~~

- Workspace tokio-util now requires the "rt" feature for TaskTracker.
- The mDNS worker still runs in spawn_blocking and may stay parked
  briefly between 250ms polls — acceptable for a desktop app.
- The 2s shutdown timeout on app exit is a deliberate compromise.

Tests
~~~~~

New unit tests:
  - DownloadStateGuard clears tracking on completion, cancellation, and
    parent-task abort (context.rs).
  - Required failure cancels the runtime and emits RuntimeFailed
    (startup.rs).
  - Restart policy restarts until shutdown is requested (startup.rs).
  - PeerRuntimeHandle.shutdown() observable via wait_stopped()
    (startup.rs).
  - Peers-gone cancellation emits only PeersGone, no duplicate Failed
    (services/liveness.rs).

Test plan
~~~~~~~~~

  cargo test --workspace
  cargo clippy --workspace --all-targets

Manual smoke test on two peers on the same LAN:
  1. Start a download, verify chunks transfer.
  2. Close the receiving app mid-download — verify the sending peer
     logs a Goodbye, not a connection-reset error.
  3. Stop the sending peer mid-download — verify the receiver emits
     DownloadGameFilesAllPeersGone, not Failed.

Follow-ups
~~~~~~~~~~

- Frontend handler for "peer-runtime-failed".
- Consider exposing the runtime handle's stopped watch to the frontend
  for a reconnecting indicator on Required failures.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-15 07:53:51 +02:00
ddidderr b4585b663a ChatGPT Codex 5.5 xhigh refactored even more 2026-05-02 15:31:37 +02:00