Merge branch 'fix/large-download-paths'

Concurrent-transfer limits, with the queue, the pause and the flag day.

A node now caps how many transfers it runs at once (8 downloads, 8 uploads,
node-wide) and how many one member may run in one group (2 by default,
operator-signed). Beyond that the node answers "queued" and the client waits its
turn, visibly, in the transfers panel — and a slot that frees starts whatever is
next, skipping past a member who is at their own cap rather than letting them
stall everyone behind them.

Browsing is never subject to a slot: not the poster grid, not the covers, not
opening a photo to look at it. That is structural — a transfer is what the
transfers widget shows — and the exemption is bounded rather than open, at two
files in flight per session, because an exemption with no bound is a leaseless
branch under another name.

Transfers can be cancelled, and now paused and resumed. A paused one holds
nothing: its slot goes back at once and resuming rejoins the queue at the tail.
Uploads survive the connection that started them and resume where the node
stopped, asked for inside the seal rather than on a clear message. What they
leave behind when they are abandoned is reaped, which closes a disk leak that
predates this work.

MNP 3.0 makes the lease compulsory and refuses 2.x at the handshake, with the
desktop client checking `client.minimum` before connecting so an un-updated one
says "update" instead of failing every connection in a protocol vocabulary.

Fourteen defects were found on the way, eight of them by a person clicking
Download and pasting a console — none of which 2075 tests could reach. Section
12 of ~/next/improve-downloads.md is that report, including the three this work
introduced itself and the one that turned out to be caused by an instruction to
hard-reload after each deployment.

Node suite 1209 passed, hub suite 866 passed.

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

1 files changed, 21 insertions, 0 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/config.py b/packages/meshbay-node/src/meshbay_node/config.py
index 7673a51..7351b1c 100644
--- a/packages/meshbay-node/src/meshbay_node/config.py
+++ b/packages/meshbay-node/src/meshbay_node/config.py
@@ -60,6 +60,13 @@ device_request_ttl_minutes = 60
 # lower it on a Pi.
 max_concurrent_streams = 8
 
+# How many downloads and uploads run at once on this node, across every group.
+# A slot is concurrency, not bandwidth: what it protects is open file handles,
+# disk seeks and the channel buffer each transfer keeps full. Past this, a
+# member is queued and told so, and starts when a slot frees.
+max_concurrent_downloads = 8
+max_concurrent_uploads = 8
+
 # HEVC sources have no browser decoder on most platforms, so streaming one is
 # transcoded to H264 rather than the usual free copy — real CPU per viewer.
 # Set to false only if every viewer's client is known to decode HEVC itself.
@@ -157,6 +164,14 @@ class NodeConfig:
     # the node answers "server busy" — see MAX_CONCURRENT_TRANSCODES in
     # transport/webrtc_server.py for what one costs.
     max_concurrent_streams: int = 8
+    # How many transfers run at once on this node, across every group —
+    # separate pools, because a download and an upload cost different things
+    # and one queue for both makes each cap meaningless. Streaming has its own
+    # third pool (max_concurrent_streams above): a member watching a film is
+    # not charged a download slot, and a download does not make the next film
+    # answer "server busy". See meshbay_node/transfers.py.
+    max_concurrent_downloads: int = 8
+    max_concurrent_uploads: int = 8
     # HEVC (and any future codec in media_probe.py's
     # BROWSER_INCOMPATIBLE_VIDEO_CODECS) has no decoder in most browsers, so
     # streaming it needs a real re-encode to H264 rather than the usual free
@@ -332,6 +347,12 @@ def load_config(path: Path = DEFAULT_CONFIG_PATH) -> Config:
         cfg.node.max_concurrent_streams = _positive(
             nd.get("max_concurrent_streams", cfg.node.max_concurrent_streams),
             cfg.node.max_concurrent_streams, "max_concurrent_streams")
+        cfg.node.max_concurrent_downloads = _positive(
+            nd.get("max_concurrent_downloads", cfg.node.max_concurrent_downloads),
+            cfg.node.max_concurrent_downloads, "max_concurrent_downloads")
+        cfg.node.max_concurrent_uploads = _positive(
+            nd.get("max_concurrent_uploads", cfg.node.max_concurrent_uploads),
+            cfg.node.max_concurrent_uploads, "max_concurrent_uploads")
         cfg.node.transcode_incompatible_video = bool(
             nd.get("transcode_incompatible_video", cfg.node.transcode_incompatible_video))
         ice_if = nd.get("ice_interfaces")