# Project Behavior Rules

## Product Truth

- Treat bank files as immutable evidence. Never rewrite, delete, or silently
  repair an imported source row.
- Never infer a financial fact from a name alone when an account identifier,
  amount, direction, date, or balance check is available.
- A bank-side observation is not automatically an economic transfer. Deduplicate
  both sides into one canonical event before calculating any relationship.
- Same-company account transfers affect account cash positions but never enter
  intercompany balances.
- Unknown, ambiguous, or incomplete input becomes an explicit exception. Do not
  guess a template, company, account, or counterparty.
- Keep manual records separate from immutable bank rows. A manual record affects
  positions only after administrator approval and must retain its audit trail.
- Treat cashier account registration as a request. Only administrator-approved
  accounts may identify ownership, accept uploads, or affect calculations.
- Every balance shown in the UI must expose its cutoff date and unresolved
  amount.
- Keep the administrator and cashier portals as independent route-level
  surfaces with different information priorities.
- Apply the global calculation start date before any aggregation. Preserve but
  exclude earlier source rows.
- Treat cashier no-business gap attestations as audited evidence, never as
  generated bank transactions.
- Subject classification may be suggested by deterministic rules, but an
  ambiguous statutory subject must enter review rather than being guessed.

## Engineering Behavior

- Prefer deterministic parsing and validation for money, dates, account ids, and
  balance continuity. AI-like classification may suggest, never post silently.
- Keep company and account master data dynamic. Do not hard-code the current
  group roster into code or fixtures outside tests.
- Use decimal arithmetic for money. Preserve original precision and currency.
- Changes to imported facts happen through a reversal or audited adjustment,
  never by editing the source transaction in place.
- Add a focused regression test for every new bank template or parsing edge
  case. Run the complete test suite before reporting completion.
- Keep UI copy operational and specific: state, action, consequence, and
  recovery belong near the control that needs them.
- Do not expose temporary server filenames in import errors. Report the original
  filename, worksheet, scanned range, and useful candidate header rows.
- Scope company-user reads, exports, uploads, and confirmations on the server;
  UI visibility is not a permission boundary.
- Use accessible labels, visible keyboard focus, and status text that does not
  rely on color alone.
- Keep changes scoped to the requested phase. Avoid speculative integrations,
  migrations, or design-system rewrites.