# C11 — Generalized sources; record-then-replay determinism boundary

**Guarantee.** A source is anything that produces timestamped scalar streams —
market data (the data-server) and non-financial sources (e.g. a news-agent node
emitting a bias) are treated identically. Anything nondeterministic, external,
or slow (LLM/news/web) is materialized into a recorded, timestamped stream
*before* it enters the engine; a backtest replays the recording, live computes
fresh in real time and records it for future backtests. A bias enters as a value
held until the next event (firing policy A, C6).

**Forbids.** Any live external call *inside* a backtest replay.

**Why.** It is the only model compatible with reproducible backtests (C1) — LLM
calls are nondeterministic and far too slow per-cycle. External LLM (IONOS) calls
happen only at the recording/live-source edge, with explicit per-session consent,
never inside a sim (the IONOS consent rule lives in `~/.claude/CLAUDE.md`).

## Current state
The producer seam that makes "a source is anything" concrete is the object-safe
`Source` trait (`crates/aura-engine/src/harness.rs`), driven by the single k-way
ingestion merge (C3); the seam itself is detailed in C12. The realized side is the
market-data replay path: `DataServer` (the external `data-server` git-dependency
crate, re-exported through `crates/aura-ingest`)
parses an archived M1 window and streaming `M1FieldSource` producers
(`crates/aura-ingest/src/lib.rs`) replay it deterministically into the merge. The
recording *direction* — a live source materialized into a timestamped stream for
later replay — and generalized non-price recorded sources (a news-agent bias) are
design law that rides the same `Source` seam (the #71 source seam) but has not yet
landed. The held-until-next-event semantics of a sparse recorded source are the
firing-policy-A / sample-and-hold mechanism already realized under C5/C6. At the
opposite edge the live broker is an I/O adapter at the recording/deploy boundary,
never part of the strategy (C13; domain invariant 7).

## See also
- [C1](c01-determinism.md)
- [C3](c03-single-merge.md)
- [C6](c06-firing-policy.md)
- [C12](c12-atomic-sim-unit.md)
- [C13](c13-hot-reload-frozen-deploy.md)