Log prompt-io for the tpt-backend planning arc

One record covering all 9 commits on this branch, per the NLNet
generative-AI policy and the existing `ai/prompt-io/claude/`
convention.

Uses diff-ref mode for both the plan docs and the example code
(`git diff main..ng_tpts_planning -- <path>`) rather than
duplicating content already in `git log -p`. Kept verbatim in
the `.raw.md`: the four verified findings (trio's
family-agnostic `SocketStream`/`SocketListener`, the round-trip
table proving `/wg/` is infix, the proto-key `UnwrappedAddress`
rationale, and `setns(2)`'s per-thread reality), since those are
reasoning rather than diffable output.

`## Human edits` records that the steering here was substantial
and mid-session rather than post-hoc: two model claims about wg
maddr semantics were challenged and retracted (incl. in an
already-posted issue comment), and the proto-key +
netns-as-runtime-config framings were human-directed. Also notes
the one model-initiated correction — a pre-publication
self-review that downgraded the `uniffi`/asyncio thesis and the
TIPC duplicate-binder claim to explicitly-flagged assumptions.

Prompt-IO: ai/prompt-io/claude/20260813T001102Z_27c34aeb_prompt_io.md

(this patch was generated in some part by `claude-code` using `claude-opus-5` (`anthropic`))
ng_tpts_planning
Gud Boi 2026-08-12 20:36:03 -04:00
parent 27c34aebb6
commit 0c96f92396
2 changed files with 301 additions and 0 deletions

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---
model: claude-opus-5
service: claude
session: 7b9c97c4-fff7-4ac4-97fb-35720453308e
timestamp: 2026-08-13T00:11:02Z
git_ref: 27c34aeb
scope: docs+code
substantive: true
raw_file: 20260813T001102Z_27c34aeb_prompt_io.raw.md
---
## Prompt
> draft hyper detailed implementation plans for [three]
> prospective new transport (tpt) backends for tractor's `.ipc`
> layer, from four GitHub issues: TIPC (gh #378) using built-in
> linux socket API w/ `trio` interfacing, leveraging TIPC's
> built-in discovery machinery; QUIC (gh #353) using the `iroh`
> lib, ideally with the py asyncio support (via ffi) rewritten
> for trio; wg (gh #482 and/or #443) with other shuttle-able
> tpts, using `pyroute2`, as much trio wrapping as possible
> where any other async support can be replaced.
With constraints: "be only slightly speculative"; realistic given
the linked info; the plans must be workable "by another
model/provider without much discrepancy on the design or lib
selections needed"; do it all in a new `/open-wkt` off main; and
be "as modular and modern-async-python-as-nearly-functional-style
as possible."
Key follow-up prompts that changed the design mid-session:
> wg requires binding a socket on both ends of the tunnel, the
> new support we added to `py-multiaddr` in their #108 enables
> declaring this in the maddr? […] so the
> `/ip4/10.0.0.1/udp/666/ip4/192.168.0.13/tcp/80` bullet example
> from #443 isn't correct for a wg tunnel maddr and would
> actually end up looking like,
> `/ip4/10.0.0.1/udp/666/wg/<pub-key>/ip4/192.168.0.13/tcp/80` no?
> right, we're likely going to need less `tuple`-formed
> `UnwrappedAddress` usage to make them all work and/or to extend
> the unwrapped form with a proto-str, likely the key from
> `multiaddrs` no?
> better encapsulating `UnwrappedAddress` for use externally is
> really way overdue; we should likely be encouraging (if not
> preventing unwrapped) wrapped addrs always much like other
> (std) libs, `ipaddress` comes to mind.
> so iirc netns mgmt becomes a lower-level runtime config-api
> rather then an actor-app-code API which can be dynamically
> changed once the actor is up ya?
## Response summary
A research-and-planning branch, `ng_tpts_planning` — **no runtime
code touched**. Five plan docs under `ai/tpt-backends/` plus a
corrected `wg` example set under `examples/multihost/wg_lan/`,
across 9 commits.
Three design conclusions came out of the planning that outlive
the branch:
1. **`wg` is a bindspace, not a `MsgTransport`.** The `/wg/`
maddr segment is *infix*: bearer (underlay ip+udp
`ListenPort`, bound by the kernel) → `/wg/u<key>` (an
identity, bound by nothing) → overlay (the only part tractor
binds). Verified empirically by installing
`baudco/py-multiaddr@wg_support` (py-multiaddr#108) in a
throwaway venv and round-tripping each candidate form; gh
#482's original suffix form parses but is semantically
inverted.
2. **Proto-key the `UnwrappedAddress` form**, spelled with the
`multiaddr` protocol names, dispatched via
`_address_types[addr[0]]`. Kills a whole collision class
(TIPC's `(str, int)``TCPAddress`; iroh's `(str, str)`
swallowed by the UDS case) and is the recommended migration
*before* any new backend lands.
3. **netns is a runtime/boot-time config API, not an app-code
one** — `setns(2)` is per-thread and won't move
already-created sockets, so there is deliberately no
`await actor.enter_netns(...)`.
Also verified that `trio.SocketStream`/`SocketListener` are
address-family agnostic (no `AF_*` check anywhere), which is what
makes TIPC the cheapest of the three backends to add.
Four related issues were annotated with the results (#378, #353,
#482, #443); #443's body was rewritten to reflect the corrected
grammar, with no existing checkbox state changed.
## Files changed
- `ai/tpt-backends/00_shared_backend_contract.md` — normative
backend duck-type contract, registration checklist, §1.1
proto-key conclusion
- `ai/tpt-backends/01_tipc_backend.md` — TIPC plan; service
addressing, `TIPC_TOP_SRV` push registry, instance-collision
hazard, step-0 probe
- `ai/tpt-backends/02_quic_iroh_backend.md``iroh` plan;
`uniffi`→`trio` bridge, listener/stream adapters, API-truth
table
- `ai/tpt-backends/03_wg_tunnel_bindspace.md``wg`-as-bindspace
plan; verified maddr grammar, 3-owner split, netns reality
- `ai/tpt-backends/README.md` — index
- `examples/multihost/wg_lan/wg_maddr.py` — frozen `msgspec`
tunnelled addr + pure parse/render helpers; impure
`verify_wg_peer()` kept separate
- `examples/multihost/wg_lan/host_a_srv.py` — host-A actor tree
- `examples/multihost/wg_lan/host_b_client.py` — host-B dialer
- `examples/multihost/wg_lan/README.md` — grammar, owner table,
setup, "what changed vs #482"
## Human edits
Substantial human steering rather than post-hoc editing; the
corrections were applied by the model in-session after being
challenged:
- rejected an initial claim that `wg` has "nothing to bind at the
tunnel layer" and supplied the correct composed maddr form,
which forced a rewrite of plan 03 §3.2 and a retraction in the
already-posted #443 comment
- rejected a supporting claim that `/ip4/../udp/443/quic-v1` was
"also composed"
- directed the proto-key/`ipaddress`-discipline conclusion and
the netns-as-runtime-config framing, both of which were then
folded back into the docs
- chose the commit boundaries and authored all commits; ran every
`git` mutation (commit, rebase, push) themselves
One model-initiated correction pre-publication: a self-review
downgraded two overconfident claims (the `uniffi`/asyncio thesis
and TIPC duplicate-binder behaviour) to explicitly-flagged
assumptions before the #353/#378 comments were posted.

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---
model: claude-opus-5
service: claude
timestamp: 2026-08-13T00:11:02Z
git_ref: 27c34aeb
diff_cmd: git diff main..ng_tpts_planning
---
# Raw output — next-gen tpt-backend implementation plans
## Generated planning docs
> `git diff main..ng_tpts_planning -- ai/tpt-backends/`
Five markdown docs. `00_shared_backend_contract.md` is normative
and the other three are written against it so they can be worked
independently:
- **`00_shared_backend_contract.md`** — the backend duck-type
(`<Proto>Address(msgspec.Struct, frozen=True)` + module-level
`start_listener()`/`close_listener()` + a
`Msgpack<Proto>Stream(MsgpackTransport)`), the
`inspect.getmodule(self.addr)` reflection in
`Endpoint.start_listener()` that forces the Address class and
its listener fns to share a module, a 10-item registration
checklist, the dep policy, the test-harness shape, and §1.1's
proto-key conclusion (below).
- **`01_tipc_backend.md`** — service addressing via
`TIPC_ADDR_NAMESEQ` (bind/publish) and `TIPC_ADDR_NAME`
(connect/lookup), `TIPC_TOP_SRV` topology subscriptions as a
push-based registry, the `get_random()` instance-collision
hazard, and a step-0 capability-probe spike.
- **`02_quic_iroh_backend.md`** — `iroh` over
`aioquic`/`quiche`/`trio-asyncio`, a `_uniffi_trio.py` bridge
built on `TrioToken.run_sync_soon()`, `trio.abc.Listener`/
`HalfCloseableStream` adapters, and an API-truth table to fill
in during step 0.
- **`03_wg_tunnel_bindspace.md`** — `wg` as a *bindspace* rather
than a `MsgTransport`, a `TunnelledAddress` wrapper delegating
`.proto_key`/`.unwrap()` to `.inner`, `pyroute2` for layer B,
and `@acm`-managed netns/iface for layer C.
- **`README.md`** — index.
## Generated example code
> `git diff main..ng_tpts_planning -- examples/multihost/wg_lan/`
- `wg_maddr.py``WGTunnelledAddr(msgspec.Struct, frozen=True)`
carrying `bearer: tuple[str, int]`, `peer_pubkey: str`,
`inner: tuple[str, int]`, `inner_proto: Literal['tcp']`, plus a
`.maddr` property that re-renders the canonical form. Pure
helpers `mb_pubkey()`, `wg8_pubkey()`, `parse_wg_maddr()`, and
`_segments()` (with a marked stopgap for when the `wg` codec
isn't installed). `verify_wg_peer()` is impure **by design** and
kept out of the parse path.
- `host_a_srv.py` / `host_b_client.py` — the two-host runs; both
pass only `addr.inner` to `open_nursery()`/`open_root_actor()`.
- `README.md` — grammar, owner table, `#108`-branch install line,
tunnel setup, "what changed vs #482".
## Verified findings (non-code, verbatim)
### `trio` is address-family agnostic
Read against the installed `trio`. `SocketStream`/`SocketListener`
ctor checks are only "is a trio sock object" + `type ==
SOCK_STREAM`, plus an `OSError`-**suppressed** `SO_ACCEPTCONN`
probe. No `AF_*` check anywhere; `TCP_NODELAY`/`TCP_NOTSENT_LOWAT`
are set under `suppress(OSError)`. A TIPC `SOCK_STREAM` sock should
therefore drop straight into `trio.serve_listeners()` with the
existing `MsgpackTransport` framing, making TIPC mostly
table-registration boilerplate w/ zero new deps.
### the `wg` maddr grammar — `/wg/` is infix, not suffix
Installed `baudco/py-multiaddr@wg_support` (PR
multiformats/py-multiaddr#108) into a throwaway venv and
round-tripped every candidate form:
| maddr | `[p.name for p in m.protocols()]` |
| --- | --- |
| `/ip4/1.2.3.4/udp/51820/wg/u<k>` | `['ip4','udp','wg']` |
| `/ip4/../udp/../wg/u<k>/ip4/../tcp/..` | `['ip4','udp','wg','ip4','tcp']` |
| `/ip4/10.0.11.1/tcp/1616/wg/u<k>` | `['ip4','tcp','wg']` |
```
/ip4/192.168.1.50/udp/51820/wg/u<A_pub>/ip4/10.0.11.1/tcp/1616
\_______ bearer __________/\__ key __/\______ overlay ______/
```
Segments *before* `/wg/` are the bearer — the underlay
`(ip, udp-port)` that `wg(8)` itself listens on (`ListenPort`).
Segments *after* are the overlay endpoint, the only part tractor
binds. The third row above is #482's original suffix form: it
parses, but is semantically inverted.
Three parts, three owners — and only one is an `Endpoint`:
| part | bound by | in the runtime? |
| --- | --- | --- |
| bearer | kernel, via `wg-quick`/`pyroute2` | no |
| `/wg/u<key>` | nothing — an identity | no, verified out-of-band |
| overlay | `tractor`'s `IPCServer` | yes, as `.inner` |
### proto-key-tagged `UnwrappedAddress`
Shape-matching in `wrap_address()` does not survive four backends.
TIPC's natural unwrapped form is a `(str, int)`, indistinguishable
from `TCPAddress`; iroh's is a `(str, str)`, already swallowed by
the existing UDS case (`case (_, filename) if type(filename) is
str`). Ordering hacks and prefix-tagging only paper over it.
Recommended prerequisite for all three backends: carry an explicit
proto-key spelled with the `multiaddr` protocol name —
`('tcp', host, port)`, `('unix', path)`,
`('tipc', stype, inst, scope)` — so `wrap_address()` collapses to
`_address_types[addr[0]]` and the collision class stops existing.
This also makes the on-wire form agree with
`mk_maddr()`/`parse_maddr()` instead of being an independent
invention. It is a wire-format change (`SpawnSpec`,
`_root_mailbox`, `_registry_addrs`) plus every fixture and
downstream config, so it wants its own migration commit landed
before any new backend — and it is the moment to stop handing raw
tuples to users at all, making `Address` the public currency and
`UnwrappedAddress` an internal serialization detail (the
discipline `ipaddress` uses).
### netns is a runtime-level config API
`setns(2)` affects the calling thread only and does not move
already-created sockets. So a netns is a spawn/boot-time input
alongside `enable_transports`/`tpt_bind_addrs`, and there is
deliberately no `await actor.enter_netns(...)` — a mid-life API
would silently leave the IPC server bound in the old namespace.
Corollary for layer B: pass `netns=` down to `pyroute2` rather
than assuming a `trio.to_thread` worker inherits it.
### `examples/` collection would have failed CI
`tests/test_docs_examples.py` walks `examples/` recursively and
subproc-runs every collected file asserting `rc == 0`. Its filter
never checks the extension, so all four `wg_lan` files were
collected — including `README.md`, which would have been run as
`python README.md`. `'multihost' not in p[0]` was already in the
exclusion list with no directory using it. Moving the set under
`examples/multihost/wg_lan/` drops collection 24 → 20 with zero
test changes; confirmed via `pytest --collect-only`.
## Corrections applied during the session
The human corrected two claims that had been asserted without
verification, both since retracted in-place in the docs and in the
posted issue comments:
1. that `wg` has "nothing to bind at the tunnel layer, exactly one
bind" — wrong; a wg stack is genuinely composed, and the real
axis is *who owns* each layer's endpoint.
2. that `/ip4/../udp/443/quic-v1` was "also composed" — wrong;
that is one endpoint with a protocol qualifier, not a tunnel.
A self-review before publication also downgraded two
overconfident claims to explicitly-flagged assumptions: the
`uniffi`-uses-asyncio-only-as-executor thesis (contradicted that
plan's own "do not guess from memory" step 0) and TIPC's
duplicate-binder round-robin behaviour (unverified).