tines/AGENTS.md

AGENTS.md — tines

Instructions for AI agents working on tines: opportunistic shared memory for mostly-offline robots. Read this before touching code.

What tines is

Small robots collect facts about the world while mostly offline. When two of them happen to meet in range, they swap what they know so each one's picture of the world improves. No robot depends on receiving anything, but there is no reason not to share.

tines is the library that does this: a store of timestamped-by-age observations, a belief layer derived from them, and a delay-tolerant exchange protocol over any datagram link. Read the full intent, goals, anti-goals, and architecture in the spec first:

• Core design (authoritative): docs/superpowers/specs/2026-10-16-tines-design.md
• Addressed delivery (authoritative): docs/superpowers/specs/2026-10-18-tines-addressed-delivery.md
• Implementation plans: docs/superpowers/plans/

The plans argue from the specs. Where a plan is silent, the spec rules. Do not edit the specs or the plans — they are design history, not source. README.md is the user-facing overview and should track the code.

Architecture (three layers)

 memory — "my priors": beliefs per topic, derived from storage under a policy
 storage — append-only log of raw observations; local trimming policy
 comms   — contact-driven exchange of observations; transport trait + adapters

Only observations cross the wire. Memory is a pure function of storage plus a policy and is never transmitted. See the spec's "Architecture" section for the Observation, Store, BeliefPolicy, Transport, and exchange protocol details.

Workflow

Changes are TDD: write the failing test → see it fail → implement → see it pass → commit.

1. Keep the public API small. New public names in tines-core (types, trait methods, functions) need a reason; call them out when you add them.
2. Before committing, run the full gate, which is what CI runs: sh scripts/ci.sh (fmt, clippy and rustdoc with warnings as errors, tests with and without alloc, and the thumbv7em-none-eabihf build).
3. Use conventional commit messages (fix(core): …, ci: …, docs: …).

The Node facade is core, not application glue: an application on any target should only need to construct a Node with its NodeId, store, and transport, call poll() in its loop, and observe() when it sees something.

Hard constraints (non-negotiable in tines-core)

• tines-core is #![no_std]; alloc is a cargo feature (default on). With --no-default-features it must build for thumbv7em-none-eabihf. Only MemStore may require alloc.
• No async, no threads, no I/O, and no panic on untrusted input in core. Every frame from the wire is untrusted: malformed bytes are dropped, never unwrapped.
• Core never maps a transport Addr to a NodeId; every frame carries the sender's NodeId.
• Identity hash covers (observer, seq, topic, payload, to) only. age_ms, observed_at and lifetime_ms are excluded.
• Addressed observations (to = Some) never appear in a summary Bloom filter, and an addressed observation past its lifetime_ms is never stored or forwarded.
• Node::next_seq() must be persisted by the application across reboots (boot_count << 32 | counter); a repeated seq after reboot collides in the ID hash and must dedupe silently (insert returns Ok(false)).
• NodeId = [u8; 16], ObservationId = [u8; 16], Tick = u64 (local monotonic ms, supplied on every call).

Review Focus (each covered by a test; keep it that way)

1. Reused seq after reboot → store dedupes, insert returns Ok(false).
2. Oversized topic/payload at observe() → Err(TooLarge), never truncate/panic.
3. Garbage frames → dropped, no panic, no store change.
4. Frame from an address with no prior Contact → treated as implicit contact.
5. Tick going backwards → age saturates at stored value, never underflow.
6. Every emitted frame fits the transport's mtu(), including summaries.

Compile-time constants (tines-core/src/consts.rs)

MAX_TOPIC=64, MAX_PAYLOAD=1024, MAX_PEERS=8, SUMMARY_BYTES=512, BLOOM_K=3, SUMMARY_INTERVAL_MS=2000, REASSEMBLY_TIMEOUT_MS=5000, SEND_QUEUE_CAP=256, MAX_FRAME=1500. Match the exact values above.

Crate layout

tines/
  tines-core/   no_std core: Observation, Store/Transport/BeliefPolicy traits,
                exchange state machine, Node facade, in-memory store, reference
                policies
  tines-sim/    std: simulator, contact traces, convergence and relay
                property tests

Not started

tines-udp, tines-sqlite, tines-cli, and tines-serial (from the core spec's crate layout) belong to a future plan. Don't start them unless asked.