Implements #3: DataServer::symbol_meta(symbol) -> Option<InstrumentGeometry>
loads a <SYMBOL>.meta.json sidecar from the owned data directory and returns
neutral, broker-agnostic price geometry (digits, pip_size, tick_size,
lot_size, base, quote). A consumer can now obtain a symbol's bars and its
price-interpretation geometry from one server.
Design (forks logged on #3):
- Neutral output is the struct's shape/semantics, not currency-code
normalization: base/quote pass through verbatim. The live sidecars carry
wildly heterogeneous base codes (ISO, index codes, descriptive names, stock
tickers) with no definable neutral target; the downstream consumer
cross-checks them against its own vetted table.
- Format quirks are absorbed in a pure parser (meta::from_sidecar_bytes):
scientific notation parses natively; a null / non-finite / missing core
field or an unsupported schemaVersion yields None, never a partial struct.
- A missing sidecar is a normal None (silent); a present-but-unusable one
warns to stderr, matching the existing loader's degrade-and-warn style.
- serde_json (Value extraction, no derive) is the new direct dependency,
chosen over a hand-rolled parser for robust number/escape handling; the
README dependency statement is updated to match.
- No caching and no Arc<Self>: geometry files are tiny and read rarely, and
the read needs no prefetch. Lookup is not gated on bar-index membership.
Verified: cargo build and clippy clean (0 warnings); full suite green
(7 parser unit tests + 5 symbol_meta integration tests pin each absorbed
quirk and the index-independent lookup). Cargo.lock stays untracked per the
library convention.
closes#3
High-performance, thread-safe loader and cache for binary market data
files (M1/tick). No dependency on the rest of myc; only chrono, regex, zip.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Brummel