Import Price Bug Fix

notes/purchase_trade_import_prices_backlog.md

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+# Purchase Trade Import Prices Backlog
+
+Backlog of potential issues found during a targeted review of the
+`purchase_trade.import_prices` wizard.
+
+## Findings
+
+### Incomplete auto-created price indexes
+
+- Area: `modules/purchase_trade/pricing.py`, `_price_index_values`
+- Risk: medium
+- Current behavior: when `create_missing_price_index` is enabled, the wizard
+  creates a `price.price` even if default references cannot be found.
+- Details: default references are searched by exact names: `Market price`,
+  `USD`, `Argus EU`, and `Mt`.
+- Possible impact: imported prices may be attached to indexes without unit,
+  currency, type, or calendar, which can later break or distort price
+  conversions.
+- Suggested action: fail clearly when required defaults are missing, or expose
+ /import a controlled mapping instead of relying on silent best-effort lookup.
+
+### Duplicate price values for the same index and date
+
+- Area: `modules/purchase_trade/pricing.py`, `_import_rows`; `modules/price/price_value.py`
+- Risk: medium
+- Current behavior: the wizard searches an existing `price.price_value` with
+  `limit=1` for a given `price` and `price_date`.
+- Details: no uniqueness constraint was found on `price.price_value` for
+  `(price, price_date)`.
+- Possible impact: if duplicates already exist, only one record is updated, and
+  later price reads may use a non-deterministic record.
+- Suggested action: add a duplicate detection step in the import wizard. Longer
+  term, consider a unique constraint or a cleanup/migration if the database
+  already contains duplicates.
+
+### Strict forward month term formats
+
+- Area: `modules/purchase_trade/pricing.py`, `_as_month_term`
+- Risk: low to medium
+- Current behavior: forward month columns accept Excel date values or text in
+  `YYYY-MM` format.
+- Details: common business labels such as `MAR26`, `Mar-26`, or `March 2026`
+  are rejected.
+- Possible impact: valid user files may fail with `Invalid month term`.
+- Suggested action: confirm the real Excel template used by operators. If
+  needed, support month abbreviations while keeping unambiguous validation.
+
+### Fragile text number parsing
+
+- Area: `modules/purchase_trade/pricing.py`, `_as_float`
+- Risk: low to medium
+- Current behavior: blank values become `None`; comma decimals such as `75,25`
+  are accepted.
+- Details: formatted text numbers such as `1 234,56`, `1,234.56`, or values
+  with non-breaking spaces are not handled safely.
+- Possible impact: imports may fail on files where prices are pasted as
+  formatted text instead of stored as numeric Excel cells.
+- Suggested action: normalize spaces and common thousand separators, or produce
+  a clearer validation error with row/index context.
+
+### Excel 1904 date system is not handled
+
+- Area: `modules/purchase_trade/pricing.py`, `_as_date`
+- Risk: low
+- Current behavior: numeric Excel dates are interpreted with the 1899-12-30
+  base.
+- Details: Excel workbooks using the 1904 date system would be shifted by about
+  four years.
+- Possible impact: imported `price_date` or forward month terms could be wrong
+  for uncommon workbook settings.
+- Suggested action: inspect workbook properties for the date system before
+  converting numeric dates.
+
+## Recently Fixed
+
+### Forward prices only populated `price_value`
+
+- Area: `modules/purchase_trade/pricing.py`, `_read_forward_price_rows`
+- Status: fixed locally
+- Change: forward imports now copy each forward cell value into `price_value`,
+  `open_price`, `low_price`, and `high_price`.
+- Regression coverage: `test_import_forward_prices_copies_value_to_ohl_fields`
+  in `modules/purchase_trade/tests/test_module.py`.