docs(design): 054 zero-alloc connector boundary, 055 wildcard inbound links, 056 aimdb join CLI

[lxsaah]

Description

Three separate design documents, a revision of 043, and an allocation benchmark that grounds 054 in measured numbers. No production code changes.

Benchmark: aimdb-bench/benches/b0_alloc_connector.rs
Measures per-message heap allocations at the connector boundary on a no-op connector (Tokio, current-thread), with the results committed in data/baselines/b0_alloc_connector.json:

Path	Allocs/msg
Router::route (64 routes, deserialize + produce)	0
pump_source with a minimal Source	2
outbound recv_into + Connector::publish, scratch serializer	2
same, dynamic topic (TopicProvider)	3
same, owned serializer	3

The bench asserts these values exactly, so a regression or an improvement fails it until EXPECTED and the baseline are updated together.

054 — Zero-allocation connector boundary. Buffers, the consume path (037) and routing already allocate nothing; every remaining per-message allocation comes from the connector interfaces (boxed futures, owned topic Strings). Extends 037's poll-based approach to the connector boundary:

• inbound: borrowed push via InboundDispatch, and a poll-based Source;
• outbound: a poll-based SerializedReader, per-route RoutePublisher (poll_ready/start_send), and a TopicWriter that writes topics into scratch storage;
• MQTT specifics per backend, guidance for heap-containing values, and target numbers for each bench row.

This is an SPI break (next major); user-facing APIs are unchanged.

055 — Wildcard inbound links. Additive and independent of 054:

• the connector supplies the topic grammar (TopicGrammar, MQTT_GRAMMAR);
• named captures ({device}), available to the deserializer through RuntimeContext;
• optional KeyId interning with a bounded table per link.

It costs one allocation per message on pattern routes only, which goes away once 054 lands.

056 — aimdb join CLI. Ports the implementation from the planning branch (e0dcf9b; it compiles on main and its 9 tests pass) and fixes five review defects:

• the OAuth client ID was compiled in; it now comes from discovery;
• end of input looped forever, and the prompts were deployment-specific; the command no longer prompts;
• file permissions were wrong when overwriting, and existing profiles were overwritten silently; profiles are now written atomically and only replaced with --force;
• http:// was accepted; https:// is now required except for loopback.

It also defines distinct exit codes and a test plan.

043 rev 2. Made deployment-neutral:

• a discovery request (GET /v1/join);
• optional app values in both directions;
• node_id instead of the slot-based station_id;
• credential rotation allowed on re-join;
• 422 and 429 errors;
• the broken link to the absent 042 flagship spec is removed.

Revised in place, since it is still Proposed and no server implements it.

Related Issue

• None

Checklist

• I have read the CONTRIBUTING.md document.
• My code follows the project's coding standards. (cargo fmt and cargo clippy -p aimdb-bench --all-targets -- -D warnings clean)
• I have added tests to cover my changes. (the bench asserts its expected values)
• All new and existing tests passed (make check). Not run in full: only cargo bench -p aimdb-bench --bench b0_alloc_connector and clippy on aimdb-bench were run.
• I have updated the documentation accordingly. (aimdb-bench/README.md)

Known, left out of scope: docs/design/044-embassy-mqtt-tls.md still links to 042-public-weather-mesh-flagship.md, which is not on main.

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