The BidiStreamSource trait (ADR-070) made Connection hold Box<dyn
BidiStreamSource> so downstream crates can add connection shapes without
editing core — but the public constructor for that path was missing.
The source field is private; the channels crate (or any future crate)
had no way to build a Connection from its own BidiStreamSource impl.
The trait was unusable from outside core.
Add Connection::from_source(source: impl BidiStreamSource, alpn: Vec<u8>)
-> Self: the extension point. Takes impl BidiStreamSource (not Box<dyn>)
to match the ergonomic style of from_stream / from_bidi; boxes the
source internally. No feature gate (always available, like from_stream).
Initializes alpn and identity: OnceLock::new() the same as the other
constructors.
Test: a custom RecordingSource BidiStreamSource impl (not a built-in)
constructed via from_source, verifying remote_alpn / remote_addr /
accept_bi (round-trips real bytes via tokio::io::duplex) / open_bi
(StreamClosed) / close (records code+reason) all delegate to the custom
impl.
Verified: cargo test + clippy clean across default, --no-default-features,
--features iroh, --all-features; cargo check -p alknet-call succeeds
unchanged; cargo fmt --check passes.
ADR-070 made Connection hold Box<dyn BidiStreamSource> so downstream
crates can add connection shapes without editing core. The trait and
three built-in impls landed, but the public constructor that lets a
downstream crate construct a Connection from its own BidiStreamSource
impl was never added — the source field is private with no from_source
constructor. The channels POC update surfaced this when it tried to
use the trait directly and found no way to build a Connection from a
ChannelBidiStreamSource.
This is a gap in the ADR-070 implementation, not a new decision. ADR-070
§Consequences says 'the channels crate implements ChannelBidiStreamSource
in its own crate and constructs Connection from it' — the constructor for
that path is what was missing.
- ADR-070: add from_source to the Constructors table + reword the
downstream-crates paragraph to make the two paths explicit
(from_source for custom impls; from_quinn/from_iroh/from_stream for
built-in impls)
- core-types.md: add from_source to the impl Connection block, the
built-in implementations table, and the design-decisions table entry
- tasks/core/connection-from-source-constructor.md: the implementation
task (one constructor + one test, scope narrow, risk low)
glm-5.2