Add an append-only, hash-chained store of every collected Siamchart
fundamental snapshot so the 40% fundamental dimension can be reconstructed
at a historical date instead of always reading the latest snapshot:
- backend/app/siamchart_vintages.py: SiamchartVintageStore persists each
snapshot under its retrieved_at with a SHA-256 canonical hash chain
(tamper/reorder detectable); snapshot_at(as_of) returns the newest
snapshot whose retrieved_at <= as_of (anti-look-ahead), and fails closed
(returns {}) when none is knowable yet. Deduplicates identical
retrieved_at+body persists.
- backend/app/pit_scorer.py: PitScoreProvider accepts siamchart_store; when
wired, siamchart_factor_view reads the snapshot knowable at as_of
(pit_grade='pit') instead of the current snapshot (pit_grade='current').
score_board no longer forces partial_pit when a store is present — the
fundamental dimension is PIT; the theme dimension still fails closed
(pit=false) unless every theme factor has a released PIT value by as_of.
- backend/app/__init__.py: /api/v1/backtest use_pit seeds the first vintage
from the current snapshot (idempotent) and wires the store.
- tests: store (6) + scorer-with-store anti-look-ahead (1) — full backend
suite 273 passed.
Honest scope: snapshots are stored whole and reconstructible forward;
EPS year-keys inside a snapshot are not tied to calendar years, so EPS
growth stays latest-vs-prior (not fiscal-year-pinned). No history before the
first collected snapshot exists.
Add a point-in-time (PIT) factor/data store and a score provider so the
backtest engine can rebuild per-symbol scores from data actually knowable
at a given date, instead of silently reusing the live board:
- backend/app/factor_vintages.py: append-only, provenance-complete store
(observed_at/released_at/retrieved_at) with a SHA-256 canonical hash chain.
value_at(as_of) only ever returns rows whose released_at <= as_of (real,
testable anti-look-ahead); no value by as_of fails closed (returns None).
- backend/app/pit_scorer.py: PitScoreProvider computes theme surprises from
PIT factor values only, and a partial siamchart fundamental view (EPS
growth from the 5-year series; current ratios marked partial). score_board
attaches pit_meta so callers can tell PIT from fallback.
- backend/app/backtest.py: _resolve_scores now sets leakage_guard ONLY when
the supplied score_fn's meta asserts pit_meta.pit=true; an arbitrary
callable with no PIT proof is no longer treated as PIT (closes the
'supplied fn => PIT' hole).
- backend/app/__init__.py: /api/v1/backtest accepts use_pit, wiring the PIT
provider; _load_siamchart_snapshot loads the SET50 fundamental snapshot.
- tests: factor store (9), pit scorer (5), backtest leakage-guard gating (2
new + 1 corrected) — full backend suite 255 passed. Empty store fail-closes
(leakage_guard=false) as proven by a live route probe.
Honest scope: theme dimension is PIT from this store forward; siamchart
fundamental remains partial (current ratios) and is flagged as such. No
historical factor data before today exists, so pre-today backtests remain
non-PIT by construction.
