完善差旅补助规定与费用类型（07-28-travel-reimbursement-guide）

.trellis/spec/hyb-oa/reimbursement-invoice-ocr.md

@@ -383,6 +383,96 @@ node scripts/qa/check-ocr-provider-samples.mjs \
 The caller records stdout before applying the exit-code gate; it never uses a
 `set -e` assignment whose non-zero status exits before the JSON is emitted.
 
+## Scenario: Travel Allowance Expense-Type Boundary
+
+### 1. Scope / Trigger
+
+- Trigger: adding or changing travel reimbursement types, travel-request
+  transport mappings, allowance policies or expense standards.
+- Purpose: keep intercity transport reimbursed by evidence separate from the
+  two daily lump-sum allowances, and avoid false over-limit results until the
+  reimbursement item model supports a day count.
+
+### 2. Signatures
+
+- Seed contract in `server/src/scripts/seed-config.js`:
+  - `travel_bus` -> `大巴车票`.
+  - `travel_meal` -> `伙食补助费`.
+  - `travel_local_transport_allowance` -> `市内交通补助费`.
+- Travel conversion contract in `server/src/routes/reimbursements.js`:
+  `TRAVEL_TRANSPORT_EXPENSE_TYPE_CODES.bus === "travel_bus"`.
+- Current item data boundary: `ReimbursementItem` stores expense type, date,
+  amount and description, but no quantity or eligible-day count.
+
+### 3. Contracts
+
+- `travel_bus` always means an intercity bus/coach ticket created from or used
+  with a travel segment. It must not represent local transport allowance.
+- Meal allowance is CNY 100 per eligible person-day; local transport allowance
+  is CNY 80 per eligible person-day. Both are lump-sum items without an invoice.
+- Employees create one item per allowance, set the amount to eligible days
+  multiplied by the rate, and write the date range, day count, rate and formula
+  in the description. Supervisor and finance review that calculation.
+- Departure and return dates each count as one natural day; same-day return is
+  one day. Personal extensions do not count. Meals or vehicles paid directly
+  by the company or another organization exclude the corresponding allowance.
+- Claiming meal allowance excludes separate personal meal reimbursement;
+  claiming local transport allowance excludes bus, metro, taxi and ride-hailing
+  reimbursement during the trip. Intercity transport, accommodation and other
+  approved necessary expenses remain evidence-based actual reimbursement.
+- `ExpenseStandard.per_unit=day` currently does not multiply `max_amount` by a
+  day count. Do not seed or configure CNY 100/CNY 80 warn/block standards until
+  item quantity/day multiplication is implemented end to end.
+
+### 4. Validation & Error Matrix
+
+- Travel segment `bus` maps to an allowance type -> block the change; preserve
+  `travel_bus` and add/use the separate allowance code.
+- CNY 100 or CNY 80 daily rate configured as the current item-level maximum ->
+  remove/disable it because a multi-day allowance would be falsely over limit.
+- Allowance item lacks date range, eligible-day count, rate or formula -> return
+  for completion during supervisor/finance review; do not invent a day count.
+- Company/other party directly bore the corresponding cost -> exclude those
+  days from the applicable allowance and record the reason.
+
+### 5. Good/Base/Bad Cases
+
+- Good: a three-day eligible trip uses separate meal and local-transport items
+  whose descriptions show `3 天 × 单价`, while rail/hotel items carry PDFs and
+  required payment evidence.
+- Base: intercity coach travel uses `travel_bus` / `大巴车票` and remains an
+  actual-expense item with valid evidence.
+- Bad: rename `travel_bus` to local transport allowance, or configure a CNY 80
+  item maximum and thereby reject a valid multi-day allowance.
+
+### 6. Tests Required
+
+- Seed-default unit test asserts all three codes and Chinese names are distinct.
+- Travel-request conversion test asserts `transport_type=bus` produces an item
+  whose expense type code is `travel_bus` and description identifies `大巴`.
+- When automatic day calculation is later implemented, add service and route
+  tests for same-day, multi-day, personal-extension and directly-borne cases
+  before enabling any daily standard.
+- Documentation checks must keep the employee guide, reimbursement fact source
+  and production expense-type names aligned.
+
+### 7. Wrong vs Correct
+
+#### Wrong
+
+```js
+const TRAVEL_TRANSPORT_EXPENSE_TYPE_CODES = { bus: "travel_local_transport_allowance" };
+// Current fee control compares the whole multi-day item directly with 80.
+```
+
+#### Correct
+
+```js
+const TRAVEL_TRANSPORT_EXPENSE_TYPE_CODES = { bus: "travel_bus" };
+// Local transport allowance is a separate manually calculated item until the
+// model and fee-control service both support eligible-day multiplication.
+```
+
 ## Scenario: Payment Batch Receipt Attention Count
 
 ### 1. Scope / Trigger