Initial commit: intercompany ledger app

AGENTS.md

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+# 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.