Task: Review the FX family's data model

Produce the evidence the parent story needs: walk the Regime 2 checklist over the FX instrument family and record what holds, what does not, and which findings are recorded deferrals.

The review is read-only. It changes no model, no generated artefact and no mapper.

• Walk every Regime 2 decision check over the seven FX entity models, with the evidence for each result. Done: the results are the What holds and Findings tables of the investigation.
• Spot-check the invariant checks once and state what was read. Done: 29 domain headers, 14 codecs, the repository entities and the protocols.
• Map each finding to a criterion, with file-and-line evidence. Done: ten findings.
• Separate a defect from a recorded decision. Done: the 20 soft references, the service read loops and the nullable-string convention are recorded as component-wide, not as family oversights.
• State what was not checked. Done: the Out of scope section of the parent story.

1. Scope the family: the seven entity models, their seven tables, and the generated artefacts.
2. Classify the family against the three regimes.
3. Walk the Regime 2 decision checks per model, and the invariant checks once.
4. Read the ORE import and export seam, because the One-way numeric conversion check is decided there.
5. Re-check every critical claim in the main thread before recording it.

Measured at 2a0b0e8993, the merge base with main, on a clean checkout. The same table is in the investigation, which is where the findings that use it live.

• The review found the structural half clean and the conversion seam unmigrated. The one claim that took two passes is the conversion seam: the mapper calls exact_decimal at all 35 money sites, which reads as correct, and no FX binding carries the lexical form the exact overload needs.
• Three early findings were withdrawn during the re-check: the nested identity and audit projection, the nullable strings, and the soft references. Each is a component-wide pattern, not a family defect.

Manual QA scenarios (scaffolded via compass add test_scenario) that verify this task. Link new ones here as they're created; the scenario doc itself links back via its "Verifies task" field.

The review is recorded as Investigation: FX family data model review. Regime 2 scores 2 of 5 with debt High: the structural half is a clean 5, and the debt sits in the ORE conversion seam, one encoded-JSON column and one column that disagrees with its domain type.