Aura/CLAUDE.md

# aura — project rules

aura is a "game engine for traders": a Rust framework **and** a playground to
author trading nodes, backtest them deterministically and massively in parallel,
compose them fractally, validate them (sweep / Monte-Carlo / walk-forward), and
freeze a validated strategy into a standalone bot with a broker connection.

This file is the project sittenkodex. It imports the universal discipline from
`~/dev/skills/templates/CLAUDE.md.fragment` and adds aura's domain invariants.
The full architecture lives in the design ledger (`docs/design/`) and the specs
(`docs/specs/`), not here.

## Roles

I am the **orchestrator**, not the implementer. The skills-plugin agents are my
workers: I plan, design, decide, and integrate; they implement, refactor, test,
and diagnose. Trivial mechanical edits I may do directly; anything needing broad
reading or judgement goes to an agent. Agent reports describe intent, not
outcome — I verify the diff and the test output myself before committing.

## Commit discipline and main-branch sanctity

- **Only the orchestrator commits.** No skill agent runs `git commit`; agents
  leave their output as unstaged working-tree changes for me to inspect and shape
  into commits.
- **main HEAD is sacrosanct.** No `git reset`/`git revert` on main. main moves
  forward only via my commits. Wrong agent output is discarded with
  `git checkout -- <paths>`/`git stash`; a bad landing is fixed forward, never
  rewound.
- When a commit closes a Gitea issue, reference it in the body: `closes #N`
  (or `refs #N` for non-final work).

## Design rationale ≠ implementation effort

Design choices are justified by substance — semantics, structural fit, what the
design permits vs forbids, compositional clarity, future-proofing. Implementation
effort ("approach A touches 250 sites, B touches 1") is an observation about the
current code, not a rationale. Effort is at most a named tiebreaker after
substantive reasons tie.

## Bug fixes — TDD, always

Bug fixes are RED-first and autonomous: the failing test exists in the working
tree before any fix. The `debug` skill is mandatory for any observable
misbehaviour (failing test, panic, wrong output).

## Domain invariants (load-bearing — never silently violate)

These are the contracts the whole design rests on. A change that breaks one is a
design decision, not a refactor, and belongs in the ledger.

1. **Determinism.** A backtest is a deterministic, synchronous, non-concurrent
   event loop that reaches a unique state after each input tick. Same input →
   same run, reproducibly. Two backtests are fully disjoint → concurrently
   executable without locking. Parallelism is *across* sims, never within one.
2. **Causality / no look-ahead.** A node sees only the past. Look-ahead is made
   structurally impossible (read-only input windows that end at the cursor;
   resamplers emit a bar only once it is complete), not merely discouraged.
3. **One merge, at ingestion only.** Heterogeneous timestamped sources are
   k-way-merged into a single chronological cycle stream at the ingestion
   boundary. There is no merge / as-of join inside the graph.
4. **The four scalar base types, streamed as SoA.** Only `i64`, `f64`, `bool`,
   `timestamp` are streamed, as columnar Structure-of-Arrays. Composite streams
   (e.g. OHLCV) are bundles of base columns. Non-scalars (String, Records,
   tables, calendars) exist as metadata beside the hot path, never in it.
5. **Acyclic dataflow.** The graph is a DAG; the only feedback path is an
   explicit delay/state node (the RTL "register"). The "cycle" of the research
   workflow is not a dataflow cycle.
6. **Record-then-replay determinism boundary.** Anything non-deterministic,
   external, or slow (LLM news agents, web sources) is materialized into a
   recorded, timestamped stream *before* it enters the engine. The sim never
   makes a live external call mid-replay. (See `~/.claude/CLAUDE.md` for the
   IONOS consent rule: external LLM calls happen at the recording/live-source
   edge, with explicit per-session consent, never inside a backtest.)
7. **Strategy result is a broker-independent position table.** A strategy
   outputs not an equity curve but a time-ordered table of position events
   (`event_ts, action[buy/sell/close], position_id, instrument_id, volume`; a
   position's open time is its opening event's `event_ts`); the set of open
   positions at t is its state. Brokers are downstream **consumer nodes** (not part
   of the strategy) that consume the position-event stream (plus prices) and emit
   an equity stream; several can be attached to the same position table at once,
   giving directly comparable curves. Neutral evaluation uses a deterministic,
   frictionless sim-optimal broker producing synthetic equity in **pips**;
   realistic broker nodes add real friction/constraints in currency for viability
   and deploy.
8. **Deploy artifacts are frozen.** Hot-reload (cdylib) is an authoring-loop
   tool only. The live bot is a statically-linked, versioned, frozen artifact —
   never hot-swapped (audit trail: this bot = this commit).
9. **Engine / project separation.** This repo is the reusable *engine*. Research
   projects are separate external repos that depend on it. Project-specific
   signals live in a project's `nodes/`; cross-project-reusable nodes in shared
   crates; universal blocks in `aura-std` (shipped here). Reuse is cargo-native;
   the hot-reload unit is always the project-side `cdylib`. No user/project
   signals in this repo (only `examples/` fixtures for the engine's own tests);
   no multi-project manager or node registry inside aura.
10. **Authoring surface.** Nodes are authored in native Rust via Claude Code +
    the skills pipeline. aura ships no embedded coding-LLM. IONOS LLMs are used
    only as a runtime data source (news bias), with per-session consent, never
    in the code path.