Captures the deep dive that started as the alknet-crate-extraction
Phase 6 tangle and surfaced a layered issue:
1. Transport leaf split (ADR-092, drafted+pushed separately) — accept_bi
returns BiStream, from_stream removed, from_bidi is the only public
stream constructor. Load-bearing, separable.
2. Control channel 'isn't actually bidirectional' in TTY code (wire.rs
STREAM_CONTROL=3 one stream both sides write). ADR-071 already fixes
at wire-format level (3=ctrl_in, 4=ctrl_out); TTY code lags.
3. ADR-071's mod-3 stream_type decomposition is structural but
asymmetric (stderr baked into group shape). Cleaner framing is
mod 2/mod 4 by instance: an instance is a bidirectional unit addressed
as a contiguous block of stream_types. No control: 128
instances/channel (mod 2). With control: 64 instances/channel
(mod 4). Combined address space ~255*128 or ~255*64.
4. TTY and channels should converge on one format. Channels was
written after TTY as a natural extension (5-byte + channel_id:u32 =
9-byte). Whether TTY-direct retires the 5-byte format is a bigger
call — backward compat — flagged as POC candidate.
5. Recursive multiplexing follows: each instance can be a channels
connection. Unbounded, uniform per level via the instance framing.
Following the research-then-sync pattern: iterate here, fix
inter-document drift, sync to specs only after it settles. ADR-092 is
pushed because it's load-bearing and separable; ADR-093 (multiplexing
redesign) and ADR-094 (retire 5-byte format) draft after POCs validate.
POC candidates (ordered by leverage):
- POC 1: stderr split/recombine (load-bearing for mod 2 vs mod 3)
- POC 2: TTY-direct-as-channels (load-bearing for format convergence)
- POC 3: recursive composition (low leverage, deferred)
glm-5.2
909935ded3