fix: balance adjustments counted as spending and income — add 'adjustment' type

POST /api/accounts/{id}/adjust-balance wrote its delta as 'expense' (down)
or 'income' (up), so every downward correction surfaced as uncategorized
spending in get_monthly_spending, and every upward one as income. Opening
balances were written as 'income' too, kept out of the income total only by
a description != 'Opening balance' filter.

Backend:
- adjust_balance (routers/accounts.py) and create_account (crud.py) now
  write type='adjustment' with the signed amount. Balances are unaffected:
  SUM(amount - fee) ignores type.
- get_monthly_spending drops the description filter; spending and income
  select purely by type.
- TransactionBase gains 'adjustment' for reads; TransactionCreate does not,
  so only the server can write one.
- Migration j0e1f2a3b4c5 retypes historical rows: unlinked income/expense
  rows with the exact generated descriptions. Downgrade restores the
  typing from the sign of the amount.

Tests: cli/tests/test_adjustment.py covers spending/income exclusion, the
balance landing on target, and the migration + downgrade on a scratch DB.
test_cli's opening-balance assertion updated to the new type. 65 passed.

Docs: CLAUDE.md type list and invariant 6; spec in
docs/superpowers/specs/2026-09-30-adjustment-transaction-type.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -58,7 +58,7 @@ cli/
 - **Name resolution**: `find_account` / `find_category` map a name to the integer id every other tool takes (exact match wins, else substring). Accounts and categories are also published as the resources `fin://accounts` and `fin://categories`. There is no `get_openapi_spec` tool — the tools already cover the API and the spec is too large to be worth a tool slot.
 - **Transport**: `FIN_MCP_TRANSPORT=stdio` (default, for clients that spawn the process) or `streamable-http`, which binds `FIN_MCP_HOST:FIN_MCP_PORT` and serves MCP at `FIN_MCP_PATH` (default `/mcp`). HTTP mode sets `stateless_http` so no session affinity is required.
 - **Deployment**: its own image (`cli/Dockerfile`) and its own Deployment + ClusterIP Service in k8s — it is not mounted into the API app. Reference manifest: `deploy/k8s/fin-mcp.yaml`. In-cluster endpoint is `http://fin-mcp.apps.svc.cluster.local:8000/mcp`.
-- **Tool params are typed**: enum-valued arguments use `Literal`, so the MCP client rejects bad values before the call. In particular `create_transaction` accepts only `expense`/`income` — the API itself accepts all six transaction types, and writing a `transfer` row through it would create an orphan leg with no `linked_account_id` (invariant #1). Two-leg writes must go through `create_transfer` / `create_settlement` / `create_split_expense` / `create_splitwise_i_paid`.
+- **Tool params are typed**: enum-valued arguments use `Literal`, so the MCP client rejects bad values before the call. In particular `create_transaction` accepts only `expense`/`income` — `POST /api/transactions` also accepts `splitwise_pay`/`splitwise_receive`, and rejects `transfer`/`settlement`, which would create an orphan leg with no `linked_account_id` (invariant #1). Two-leg writes must go through `create_transfer` / `create_settlement` / `create_split_expense` / `create_splitwise_i_paid`.
 
 **Security**: `fin-mcp` has no auth of its own — it inherits whatever `FinClient` uses. With writes enabled it must stay unreachable from outside the cluster (no HTTPRoute) unless `FIN_API_TOKEN` is set on both the API and the MCP server.
 
@@ -81,7 +81,7 @@ cli/
 
 `Account` is the top-level entity with a `type` field: `bank`, `investment`, `rsu`, `splitwise`, or `receivable`. Bank accounts track cash via `Transaction` rows. Investment and RSU accounts track equity via `Holding` rows (one per ticker, unique on `account_id + ticker`). A Splitwise account records shared-expense balances.
 
-`Transaction` belongs to one account and has a `type`: `expense`, `income`, `transfer`, `splitwise_pay`, `splitwise_receive`, or `settlement`. Transfers and settlements always produce two linked rows — a debit on one account and a credit on another — connected via `linked_account_id`. The `fee` column is included in balance calculations (`amount - fee`). For Splitwise pay transactions, `splitwise_partner_share` records the partner's portion (used in spending calculations to show only the user's net share).
+`Transaction` belongs to one account and has a `type`: `expense`, `income`, `transfer`, `splitwise_pay`, `splitwise_receive`, `settlement`, or `adjustment`. `adjustment` is a single-leg correction written only by the server — opening balances on account creation and `POST /api/accounts/{id}/adjust-balance`. It moves the balance but is excluded from spending and income, because it is neither consumption nor earnings. Transfers and settlements always produce two linked rows — a debit on one account and a credit on another — connected via `linked_account_id`. The `fee` column is included in balance calculations (`amount - fee`). For Splitwise pay transactions, `splitwise_partner_share` records the partner's portion (used in spending calculations to show only the user's net share).
 
 **Idempotency**: every write that moves money accepts an optional `client_ref` — `POST /api/transactions`, `/batch`, `/transfer` and `/settlement`. Every row of one write carries the same key, and the creators check `crud.find_by_client_ref` before writing, so retrying a timed-out request replays the original rows instead of double-booking. The index is deliberately **not** unique (a transfer writes two rows under one key); duplicate suppression is a check-then-write, which is sound because SQLite serialises writers and the scheduler never writes transactions. A NULL `client_ref` means "no idempotency requested" and never collides.
 
@@ -98,7 +98,7 @@ cli/
 3. **WAL mode**: `PRAGMA journal_mode=WAL` is applied on every new connection (both the main engine and the scheduler's private engine). The scheduler runs in a background thread and must not share the request-scoped session.
 4. **Non-root Docker user**: The API Dockerfile creates user `app` (uid 1000) and runs as that user. Do not revert to root.
 5. **Balance formula**: For bank/splitwise/receivable accounts, balance = `SUM(amount - fee)` over all transactions. Do not sum `amount` alone.
-6. **Spending logic**: `splitwise_pay` expenses are counted at `amount + splitwise_partner_share` (the user's net share), not the full `amount`. This is intentional — see `get_monthly_spending` in crud.py.
+6. **Spending logic**: `splitwise_pay` expenses are counted at `amount + splitwise_partner_share` (the user's net share), not the full `amount`. This is intentional — see `get_monthly_spending` in crud.py. Spending and income select rows by `type`, never by description: anything that is not real consumption or earnings (transfers, settlements, adjustments) gets its own type so those queries skip it.
 
 ## What NOT to do
 

api/alembic/versions/j0e1f2a3b4c5_retype_balance_adjustments.py

@@ -0,0 +1,46 @@
+"""retype balance adjustments and opening balances as 'adjustment'
+
+Revision ID: j0e1f2a3b4c5
+Revises: i9d0e1f2a3b4
+Create Date: 2026-09-30
+
+POST /api/accounts/{id}/adjust-balance wrote its correction row as 'income'
+(delta > 0) or 'expense' (delta < 0), so every downward correction showed up
+as uncategorized spending and every upward one as income. Account creation
+wrote the opening balance as 'income' too, kept out of the income total only
+by a description filter. Neither is earnings or consumption — both are
+corrections to the ledger. New rows are written as 'adjustment'; this
+migration retypes the existing rows the same way.
+
+Matched on the exact generated descriptions, only on unlinked income/expense
+rows. Balances are unaffected: SUM(amount - fee) ignores type.
+
+Downgrade restores the old typing from the sign of the amount, which is exactly
+how the rows were originally typed.
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+revision: str = "j0e1f2a3b4c5"
+down_revision: Union[str, None] = "i9d0e1f2a3b4"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.get_bind().execute(sa.text(
+        "UPDATE transactions SET type = 'adjustment' "
+        "WHERE type IN ('income', 'expense') "
+        "AND linked_account_id IS NULL "
+        "AND description IN ('Balance adjustment', 'Opening balance')"
+    ))
+
+
+def downgrade() -> None:
+    op.get_bind().execute(sa.text(
+        "UPDATE transactions "
+        "SET type = CASE WHEN amount < 0 THEN 'expense' ELSE 'income' END "
+        "WHERE type = 'adjustment'"
+    ))

api/app/crud.py

@@ -31,9 +31,11 @@ def create_account(db: Session, account: schemas.AccountCreate) -> models.Accoun
     db.add(db_account)
     db.flush()  # assign the id for the opening transaction
     if initial and initial > 0:
+        # 'adjustment', not 'income': an opening balance is money that was
+        # already there, not money earned this month.
         opening = models.Transaction(
             account_id=db_account.id,
-            type="income",
+            type="adjustment",
             amount=initial,
             fee=0,
             currency=db_account.currency,
@@ -799,7 +801,6 @@ def get_monthly_spending(
         models.Transaction.date < _end,
         models.Transaction.type == 'income',
         models.Account.type.notin_(["payable", "receivable"]),
-        models.Transaction.description != 'Opening balance',
     )
     if account_id is not None:
         income_q = income_q.filter(models.Transaction.account_id == account_id)

api/app/models.py

@@ -60,7 +60,7 @@ class Transaction(Base):
     account_id = Column(Integer, ForeignKey("accounts.id"), nullable=False)
     amount = Column(Float, nullable=False)
     currency = Column(Text, nullable=False, default="EUR")
-    type = Column(Text, nullable=False)  # expense|income|transfer|splitwise_pay|splitwise_receive|settlement
+    type = Column(Text, nullable=False)  # expense|income|transfer|splitwise_pay|splitwise_receive|settlement|adjustment
     category_id = Column(Integer, ForeignKey("categories.id"), nullable=True)
     description = Column(Text, nullable=True)
     fee = Column(Float, nullable=False, default=0)

api/app/routers/accounts.py

@@ -62,27 +62,18 @@ def adjust_balance(account_id: int, req: BalanceAdjustRequest, db: Session = Dep
     if abs(delta) < 0.001:
         raise HTTPException(status_code=422, detail="Balance already matches target")
 
-    if delta > 0:
-        txn = models.Transaction(
-            account_id=account_id,
-            type="income",
-            amount=delta,
-            fee=0,
-            currency=account.currency,
-            description="Balance adjustment",
-            date=_date.today(),
-        )
-    else:
-        # Expense: store as negative amount so SUM(amount - fee) reduces the balance
-        txn = models.Transaction(
-            account_id=account_id,
-            type="expense",
-            amount=delta,  # negative, matches the sign convention used throughout crud.py
-            fee=0,
-            currency=account.currency,
-            description="Balance adjustment",
-            date=_date.today(),
-        )
+    # Typed 'adjustment', not income/expense: a correction to the ledger is
+    # neither earnings nor consumption, so spending and income must not see it.
+    # The signed delta still moves SUM(amount - fee) onto the target.
+    txn = models.Transaction(
+        account_id=account_id,
+        type="adjustment",
+        amount=delta,
+        fee=0,
+        currency=account.currency,
+        description="Balance adjustment",
+        date=_date.today(),
+    )
 
     db.add(txn)
     db.commit()

api/app/schemas.py

@@ -74,7 +74,7 @@ class TransactionBase(BaseModel):
     account_id: int
     amount: float
     currency: str = "EUR"
-    type: Literal["expense", "income", "transfer", "splitwise_pay", "splitwise_receive", "settlement"]
+    type: Literal["expense", "income", "transfer", "splitwise_pay", "splitwise_receive", "settlement", "adjustment"]
     category_id: Optional[int] = None
     description: Optional[str] = Field(default=None, max_length=500)
     fee: float = 0

cli/tests/test_adjustment.py

@@ -0,0 +1,119 @@
+"""Balance corrections — the 'adjustment' transaction type.
+
+A balance adjustment or opening balance moves the account balance but is
+neither earnings nor consumption, so it must stay out of the spending and
+income totals. Before this type existed, a downward adjustment was written as
+an 'expense' and surfaced as uncategorized spending.
+"""
+
+import os
+import sqlite3
+import subprocess
+import sys
+from datetime import date
+from pathlib import Path
+
+API_DIR = Path(__file__).resolve().parents[2] / "api"
+
+
+def _bank(client, **extra):
+    return client.create_account({"name": "Checking", "type": "bank", "currency": "EUR", **extra})
+
+
+def _balance(client, account_id):
+    return sum(t["amount"] - t["fee"] for t in client.list_transactions(account_id=account_id))
+
+
+def _month():
+    return date.today().strftime("%Y-%m")
+
+
+class TestAdjustBalance:
+    def test_downward_adjustment_is_not_spending(self, client):
+        acct = _bank(client, initial_balance=1000)
+
+        txn = client.adjust_account_balance(acct["id"], 700)
+
+        assert txn["type"] == "adjustment"
+        assert txn["amount"] == -300
+        assert _balance(client, acct["id"]) == 700
+        spending = client.get_spending_month(_month())
+        assert spending["total"] == 0
+        assert spending["categories"] == []
+
+    def test_upward_adjustment_is_not_income(self, client):
+        acct = _bank(client)
+
+        txn = client.adjust_account_balance(acct["id"], 250)
+
+        assert txn["type"] == "adjustment"
+        assert _balance(client, acct["id"]) == 250
+        assert client.get_spending_month(_month())["income_total"] == 0
+
+    def test_real_spending_still_counts_next_to_an_adjustment(self, client):
+        acct = _bank(client, initial_balance=1000)
+        client.create_transaction({
+            "account_id": acct["id"], "date": date.today().isoformat(),
+            "amount": -40, "type": "expense", "description": "Rewe",
+        })
+
+        client.adjust_account_balance(acct["id"], 900)
+
+        assert client.get_spending_month(_month())["total"] == 40
+        assert _balance(client, acct["id"]) == 900
+
+
+class TestOpeningBalance:
+    def test_opening_balance_is_an_adjustment_and_not_income(self, client):
+        acct = _bank(client, initial_balance=500)
+
+        [opening] = client.list_transactions(account_id=acct["id"])
+        assert opening["type"] == "adjustment"
+        assert opening["description"] == "Opening balance"
+        assert client.get_spending_month(_month())["income_total"] == 0
+
+
+def _alembic(db_path, *args):
+    env = {**os.environ, "DATABASE_URL": f"sqlite:///{db_path}"}
+    subprocess.run(
+        [sys.executable, "-m", "alembic", *args],
+        cwd=API_DIR, env=env, check=True, capture_output=True,
+    )
+
+
+class TestMigration:
+    def test_retypes_generated_rows_only_and_downgrades_by_sign(self, tmp_path):
+        db = tmp_path / "mig.db"
+        _alembic(db, "upgrade", "i9d0e1f2a3b4")
+        conn = sqlite3.connect(db)
+        conn.execute(
+            "INSERT INTO accounts (id, name, type, currency, is_active) "
+            "VALUES (1, 'Checking', 'bank', 'EUR', 1), (2, 'Savings', 'bank', 'EUR', 1)"
+        )
+        rows = [
+            # id, type, amount, description, linked_account_id
+            (1, "income", 500, "Opening balance", None),
+            (2, "expense", -300, "Balance adjustment", None),
+            (3, "income", 20, "Balance adjustment", None),
+            (4, "expense", -40, "Rewe", None),
+            (5, "income", 2000, "Salary", None),
+            (6, "transfer", -100, "Balance adjustment", 2),
+        ]
+        conn.executemany(
+            "INSERT INTO transactions (id, account_id, type, amount, fee, currency, description, "
+            "linked_account_id, date) VALUES (?, 1, ?, ?, 0, 'EUR', ?, ?, '2026-09-01')",
+            rows,
+        )
+        conn.commit()
+        conn.close()
+
+        _alembic(db, "upgrade", "head")
+        types = dict(sqlite3.connect(db).execute("SELECT id, type FROM transactions"))
+        assert types == {
+            1: "adjustment", 2: "adjustment", 3: "adjustment",
+            4: "expense", 5: "income", 6: "transfer",
+        }
+
+        _alembic(db, "downgrade", "i9d0e1f2a3b4")
+        types = dict(sqlite3.connect(db).execute("SELECT id, type FROM transactions"))
+        assert types == {r[0]: r[1] for r in rows}

cli/tests/test_cli.py

@@ -75,7 +75,7 @@ class TestAccounts:
         txns = client.list_transactions(account_id=acct["id"])
         assert len(txns) == 1
         assert txns[0]["amount"] == 250.0
-        assert txns[0]["type"] == "income"
+        assert txns[0]["type"] == "adjustment"
 
 
 class TestTransactions:

docs/superpowers/specs/2026-09-30-adjustment-transaction-type.md

@@ -0,0 +1,31 @@
+# Design: `adjustment` transaction type
+
+Date: 2026-09-30
+
+## Overview
+
+1. Stop balance corrections from counting as spending or income.
+2. Replace the description-string filter that kept opening balances out of income with a type.
+
+## 1. Balance adjustments
+
+`POST /api/accounts/{id}/adjust-balance` wrote its delta as `income` (delta > 0) or `expense` (delta < 0). `get_monthly_spending` counts every negative `expense` row, so a downward correction appeared as uncategorized spending, and an upward one as income.
+
+**Change**: the row is written as `type = 'adjustment'` with the signed delta. Balances are unaffected — `SUM(amount - fee)` in `net_worth.py` and in the adjust endpoint ignores `type`. Spending (`type IN ('expense','splitwise_receive')` / `'splitwise_pay'`) and income (`type = 'income'`) select by type, so they skip it with no query change.
+
+## 2. Opening balances
+
+`crud.create_account` wrote the opening balance as `income`, and the income query excluded it with `description != 'Opening balance'`. It is now written as `adjustment` and that filter is removed.
+
+## Schema
+
+No DDL — `transactions.type` is free `Text`. `TransactionBase.type` (the read schema) gains `adjustment`. `TransactionCreate` does **not**: adjustments are written only by the server, so `POST /api/transactions` cannot create one.
+
+## Migration `j0e1f2a3b4c5`
+
+Data-only. Retypes rows where `type IN ('income','expense')`, `linked_account_id IS NULL`, and `description IN ('Balance adjustment','Opening balance')` — the exact generated descriptions. Must not touch linked legs or user-entered rows. Downgrade restores the typing from the sign of `amount`, which is how the rows were originally typed.
+
+## Out of scope
+
+- Moving the adjust-balance write from the router into `crud.py` (architecture-contract weak point #2).
+- Frontend: `Transaction.type` is a plain `string` in `client.ts`, and adjustment rows stay editable like any unlinked row.

web/src/lib/utils.ts

@@ -10,9 +10,42 @@ export function todayLocalISO(): string {
   return `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, '0')}-${String(d.getDate()).padStart(2, '0')}`
 }
 
-// Accepts both 12.40 and the German 12,40. Returns null for anything that is
-// not a usable positive amount, so callers can report which row is wrong.
+// Accepts both 12.40 and the German 12,40, which is what the de-DE formatting
+// used throughout the app trains you to type. Returns null when the input is
+// not a number at all. Zero and negatives are valid — a target balance or a
+// payable can legitimately be either.
+//
+// Pair this with <input type="text" inputMode="decimal">, never
+// <input type="number">: a number input silently reports value === "" for
+// anything it considers invalid, including a decimal comma, so the bad input
+// never reaches the parser and the caller sees an empty field instead.
+export function parseDecimal(input: string): number | null {
+  const t = input.trim()
+  if (t === '') return null
+
+  const lastComma = t.lastIndexOf(',')
+  const lastDot = t.lastIndexOf('.')
+  let normalised: string
+  if (lastComma !== -1 && lastDot !== -1) {
+    // Both separators present, so the rightmost one is the decimal point and
+    // the other is thousands grouping. Without this, "1.000,50" would parse
+    // as 1 — a silent 1000x error on a balance field.
+    normalised = lastComma > lastDot
+      ? t.replace(/\./g, '').replace(',', '.')
+      : t.replace(/,/g, '')
+  } else {
+    normalised = t.replace(',', '.')
+  }
+
+  // Number() rather than parseFloat(): parseFloat stops at the first bad
+  // character, so "12.5abc" would quietly become 12.5.
+  const n = Number(normalised)
+  return Number.isFinite(n) ? n : null
+}
+
+// Same, but rejects zero and negatives — for fields that must be a positive
+// amount, so callers can report which row is wrong.
 export function parseAmount(input: string): number | null {
-  const n = parseFloat(input.replace(',', '.'))
-  return Number.isFinite(n) && n > 0 ? n : null
+  const n = parseDecimal(input)
+  return n !== null && n > 0 ? n : null
 }

web/src/pages/Settings.tsx

@@ -2,6 +2,7 @@ import { useState, useEffect } from 'react'
 import { useNavigate } from 'react-router-dom'
 import { ChevronLeft } from 'lucide-react'
 import { api, Account, Category } from '@/api/client'
+import { parseDecimal } from '@/lib/utils'
 
 export default function Settings() {
   const navigate = useNavigate()
@@ -90,10 +91,16 @@ export default function Settings() {
   }
 
   const saveAdjustBalance = async () => {
-    if (!adjustingAccount || !adjustTargetBalance) return
+    if (!adjustingAccount) return
+    // Zero and negative targets are legitimate, so parseDecimal, not parseAmount.
+    const target = parseDecimal(adjustTargetBalance)
+    if (target === null) {
+      setMutationError('Enter a target balance, e.g. 1234.56')
+      return
+    }
     setMutationError(null)
     try {
-      await api.adjustAccountBalance(adjustingAccount.id, parseFloat(adjustTargetBalance))
+      await api.adjustAccountBalance(adjustingAccount.id, target)
       setAdjustingAccount(null)
       setAdjustTargetBalance('')
       window.dispatchEvent(new CustomEvent('fin:transaction-added'))
@@ -263,8 +270,8 @@ export default function Settings() {
                   value={adjustTargetBalance}
                   onChange={e => setAdjustTargetBalance(e.target.value)}
                   placeholder="Target balance"
-                  type="number"
-                  step="0.01"
+                  type="text"
+                  inputMode="decimal"
                 />
                 <div className="flex gap-2">
                   <button