PHASE 2: Implements balance assertions for reconciliation

Adds balance assertion functionality to enable admins to verify accounting accuracy.

This includes:
- A new `balance_assertions` table in the database
- CRUD operations for balance assertions (create, get, list, check, delete)
- API endpoints for managing balance assertions (admin only)
- UI elements for creating, viewing, and re-checking assertions

Also, reorders the implementation roadmap in the documentation to reflect better the dependencies between phases.

BEANCOUNT_PATTERNS.md

@@ -866,29 +866,29 @@ async def validate_journal_entry(entry: CreateJournalEntry) -> list[CastleError]
 
 ## Implementation Roadmap
 
-### Phase 1: Foundation (High Priority)
+### Phase 1: Foundation (High Priority) ✅ COMPLETE
 1. ✅ Switch from `float` to `Decimal` for fiat amounts
 2. ✅ Add `meta` field to journal entries for audit trail
 3. ✅ Add `flag` field for transaction status
 4. ✅ Implement hierarchical account naming
 
-### Phase 2: Core Logic (Medium Priority)
-5. Create `core/` module with pure accounting logic
-6. Implement `CastleInventory` for position tracking
-7. Move balance calculation to `core/balance.py`
-8. Add comprehensive validation in `core/validation.py`
+### Phase 2: Reconciliation (High Priority) - No dependencies
+5. Implement balance assertions
+6. Add reconciliation API endpoints
+7. Build reconciliation UI
+8. Add automated daily balance checks
 
-### Phase 3: Validation (Medium Priority)
-9. Create plugin system architecture
-10. Implement `check_balanced` plugin
-11. Implement `check_receivables` plugin
-12. Add plugin configuration UI
+### Phase 3: Core Logic Refactoring (Medium Priority) - Improves code quality
+9. Create `core/` module with pure accounting logic
+10. Implement `CastleInventory` for position tracking
+11. Move balance calculation to `core/balance.py`
+12. Add comprehensive validation in `core/validation.py`
 
-### Phase 4: Reconciliation (High Priority)
-13. Implement balance assertions
-14. Add reconciliation API endpoints
-15. Build reconciliation UI
-16. Add automated daily balance checks
+### Phase 4: Validation Plugins (Medium Priority) - Works better after Phase 3
+13. Create plugin system architecture
+14. Implement `check_balanced` plugin
+15. Implement `check_receivables` plugin
+16. Add plugin configuration UI
 
 ### Phase 5: Advanced Features (Low Priority)
 17. Add tags and links to entries

crud.py

@@ -8,8 +8,11 @@ from lnbits.helpers import urlsafe_short_hash
 from .models import (
     Account,
     AccountType,
+    AssertionStatus,
+    BalanceAssertion,
     CastleSettings,
     CreateAccount,
+    CreateBalanceAssertion,
     CreateEntryLine,
     CreateJournalEntry,
     EntryLine,
@@ -765,3 +768,214 @@ async def reject_manual_payment_request(
     )
 
     return await get_manual_payment_request(request_id)
+
+
+# ===== BALANCE ASSERTION OPERATIONS =====
+
+
+async def create_balance_assertion(
+    data: CreateBalanceAssertion, created_by: str
+) -> BalanceAssertion:
+    """Create a new balance assertion"""
+    from decimal import Decimal
+
+    assertion_id = urlsafe_short_hash()
+    assertion_date = data.date if data.date else datetime.now()
+
+    assertion = BalanceAssertion(
+        id=assertion_id,
+        date=assertion_date,
+        account_id=data.account_id,
+        expected_balance_sats=data.expected_balance_sats,
+        expected_balance_fiat=data.expected_balance_fiat,
+        fiat_currency=data.fiat_currency,
+        tolerance_sats=data.tolerance_sats,
+        tolerance_fiat=data.tolerance_fiat,
+        status=AssertionStatus.PENDING,
+        created_by=created_by,
+        created_at=datetime.now(),
+    )
+
+    await db.insert("balance_assertions", assertion, convert_decimal=True)
+    return assertion
+
+
+async def get_balance_assertion(assertion_id: str) -> Optional[BalanceAssertion]:
+    """Get a balance assertion by ID"""
+    from decimal import Decimal
+
+    row = await db.fetchone(
+        "SELECT * FROM balance_assertions WHERE id = :id",
+        {"id": assertion_id},
+    )
+
+    if not row:
+        return None
+
+    # Parse Decimal fields from TEXT storage
+    return BalanceAssertion(
+        id=row["id"],
+        date=row["date"],
+        account_id=row["account_id"],
+        expected_balance_sats=row["expected_balance_sats"],
+        expected_balance_fiat=Decimal(row["expected_balance_fiat"]) if row["expected_balance_fiat"] else None,
+        fiat_currency=row["fiat_currency"],
+        tolerance_sats=row["tolerance_sats"],
+        tolerance_fiat=Decimal(row["tolerance_fiat"]) if row["tolerance_fiat"] else Decimal("0"),
+        checked_balance_sats=row["checked_balance_sats"],
+        checked_balance_fiat=Decimal(row["checked_balance_fiat"]) if row["checked_balance_fiat"] else None,
+        difference_sats=row["difference_sats"],
+        difference_fiat=Decimal(row["difference_fiat"]) if row["difference_fiat"] else None,
+        status=AssertionStatus(row["status"]),
+        created_by=row["created_by"],
+        created_at=row["created_at"],
+        checked_at=row["checked_at"],
+    )
+
+
+async def get_balance_assertions(
+    account_id: Optional[str] = None,
+    status: Optional[AssertionStatus] = None,
+    limit: int = 100,
+) -> list[BalanceAssertion]:
+    """Get balance assertions with optional filters"""
+    from decimal import Decimal
+
+    if account_id and status:
+        rows = await db.fetchall(
+            """
+            SELECT * FROM balance_assertions
+            WHERE account_id = :account_id AND status = :status
+            ORDER BY date DESC
+            LIMIT :limit
+            """,
+            {"account_id": account_id, "status": status.value, "limit": limit},
+        )
+    elif account_id:
+        rows = await db.fetchall(
+            """
+            SELECT * FROM balance_assertions
+            WHERE account_id = :account_id
+            ORDER BY date DESC
+            LIMIT :limit
+            """,
+            {"account_id": account_id, "limit": limit},
+        )
+    elif status:
+        rows = await db.fetchall(
+            """
+            SELECT * FROM balance_assertions
+            WHERE status = :status
+            ORDER BY date DESC
+            LIMIT :limit
+            """,
+            {"status": status.value, "limit": limit},
+        )
+    else:
+        rows = await db.fetchall(
+            """
+            SELECT * FROM balance_assertions
+            ORDER BY date DESC
+            LIMIT :limit
+            """,
+            {"limit": limit},
+        )
+
+    assertions = []
+    for row in rows:
+        assertions.append(
+            BalanceAssertion(
+                id=row["id"],
+                date=row["date"],
+                account_id=row["account_id"],
+                expected_balance_sats=row["expected_balance_sats"],
+                expected_balance_fiat=Decimal(row["expected_balance_fiat"]) if row["expected_balance_fiat"] else None,
+                fiat_currency=row["fiat_currency"],
+                tolerance_sats=row["tolerance_sats"],
+                tolerance_fiat=Decimal(row["tolerance_fiat"]) if row["tolerance_fiat"] else Decimal("0"),
+                checked_balance_sats=row["checked_balance_sats"],
+                checked_balance_fiat=Decimal(row["checked_balance_fiat"]) if row["checked_balance_fiat"] else None,
+                difference_sats=row["difference_sats"],
+                difference_fiat=Decimal(row["difference_fiat"]) if row["difference_fiat"] else None,
+                status=AssertionStatus(row["status"]),
+                created_by=row["created_by"],
+                created_at=row["created_at"],
+                checked_at=row["checked_at"],
+            )
+        )
+
+    return assertions
+
+
+async def check_balance_assertion(assertion_id: str) -> BalanceAssertion:
+    """
+    Check a balance assertion by comparing expected vs actual balance.
+    Updates the assertion with the check results.
+    """
+    from decimal import Decimal
+
+    assertion = await get_balance_assertion(assertion_id)
+    if not assertion:
+        raise ValueError(f"Balance assertion {assertion_id} not found")
+
+    # Get actual account balance
+    account = await get_account(assertion.account_id)
+    if not account:
+        raise ValueError(f"Account {assertion.account_id} not found")
+
+    # Calculate balance at the assertion date
+    actual_balance = await get_account_balance(assertion.account_id)
+
+    # Get fiat balance if needed
+    actual_fiat_balance = None
+    if assertion.fiat_currency and account.user_id:
+        user_balance = await get_user_balance(account.user_id)
+        actual_fiat_balance = user_balance.fiat_balances.get(assertion.fiat_currency, Decimal("0"))
+
+    # Check sats balance
+    difference_sats = actual_balance - assertion.expected_balance_sats
+    sats_match = abs(difference_sats) <= assertion.tolerance_sats
+
+    # Check fiat balance if applicable
+    fiat_match = True
+    difference_fiat = None
+    if assertion.expected_balance_fiat is not None and actual_fiat_balance is not None:
+        difference_fiat = actual_fiat_balance - assertion.expected_balance_fiat
+        fiat_match = abs(difference_fiat) <= assertion.tolerance_fiat
+
+    # Determine overall status
+    status = AssertionStatus.PASSED if (sats_match and fiat_match) else AssertionStatus.FAILED
+
+    # Update assertion with check results
+    await db.execute(
+        """
+        UPDATE balance_assertions
+        SET checked_balance_sats = :checked_sats,
+            checked_balance_fiat = :checked_fiat,
+            difference_sats = :diff_sats,
+            difference_fiat = :diff_fiat,
+            status = :status,
+            checked_at = :checked_at
+        WHERE id = :id
+        """,
+        {
+            "id": assertion_id,
+            "checked_sats": actual_balance,
+            "checked_fiat": str(actual_fiat_balance) if actual_fiat_balance is not None else None,
+            "diff_sats": difference_sats,
+            "diff_fiat": str(difference_fiat) if difference_fiat is not None else None,
+            "status": status.value,
+            "checked_at": datetime.now(),
+        },
+    )
+
+    # Return updated assertion
+    return await get_balance_assertion(assertion_id)
+
+
+async def delete_balance_assertion(assertion_id: str) -> None:
+    """Delete a balance assertion"""
+    await db.execute(
+        "DELETE FROM balance_assertions WHERE id = :id",
+        {"id": assertion_id},
+    )

migrations.py

@@ -270,3 +270,51 @@ async def m006_hierarchical_account_names(db):
             """,
             {"new_name": new_name, "id": account["id"]}
         )
+
+
+async def m007_balance_assertions(db):
+    """
+    Create balance_assertions table for reconciliation.
+    Allows admins to assert expected balances at specific dates.
+    """
+    await db.execute(
+        f"""
+        CREATE TABLE balance_assertions (
+            id TEXT PRIMARY KEY,
+            date TIMESTAMP NOT NULL,
+            account_id TEXT NOT NULL,
+            expected_balance_sats INTEGER NOT NULL,
+            expected_balance_fiat TEXT,
+            fiat_currency TEXT,
+            tolerance_sats INTEGER DEFAULT 0,
+            tolerance_fiat TEXT DEFAULT '0',
+            checked_balance_sats INTEGER,
+            checked_balance_fiat TEXT,
+            difference_sats INTEGER,
+            difference_fiat TEXT,
+            status TEXT NOT NULL DEFAULT 'pending',
+            created_by TEXT NOT NULL,
+            created_at TIMESTAMP NOT NULL DEFAULT {db.timestamp_now},
+            checked_at TIMESTAMP,
+            FOREIGN KEY (account_id) REFERENCES accounts (id)
+        );
+        """
+    )
+
+    await db.execute(
+        """
+        CREATE INDEX idx_balance_assertions_account_id ON balance_assertions (account_id);
+        """
+    )
+
+    await db.execute(
+        """
+        CREATE INDEX idx_balance_assertions_status ON balance_assertions (status);
+        """
+    )
+
+    await db.execute(
+        """
+        CREATE INDEX idx_balance_assertions_date ON balance_assertions (date);
+        """
+    )

models.py

@@ -179,3 +179,41 @@ class RecordPayment(BaseModel):
     """Record a payment"""
 
     payment_hash: str
+
+
+class AssertionStatus(str, Enum):
+    """Status of a balance assertion"""
+    PENDING = "pending"    # Not yet checked
+    PASSED = "passed"      # Assertion passed (balance matches)
+    FAILED = "failed"      # Assertion failed (balance mismatch)
+
+
+class BalanceAssertion(BaseModel):
+    """Assert expected balance at a specific date for reconciliation"""
+    id: str
+    date: datetime
+    account_id: str
+    expected_balance_sats: int  # Expected balance in satoshis
+    expected_balance_fiat: Optional[Decimal] = None  # Optional fiat balance
+    fiat_currency: Optional[str] = None  # Currency for fiat balance (EUR, USD, etc.)
+    tolerance_sats: int = 0  # Allow +/- this much difference in sats
+    tolerance_fiat: Decimal = Decimal("0")  # Allow +/- this much difference in fiat
+    checked_balance_sats: Optional[int] = None  # Actual balance found
+    checked_balance_fiat: Optional[Decimal] = None  # Actual fiat balance found
+    difference_sats: Optional[int] = None  # Difference in sats
+    difference_fiat: Optional[Decimal] = None  # Difference in fiat
+    status: AssertionStatus = AssertionStatus.PENDING
+    created_by: str
+    created_at: datetime
+    checked_at: Optional[datetime] = None
+
+
+class CreateBalanceAssertion(BaseModel):
+    """Create a balance assertion"""
+    account_id: str
+    date: Optional[datetime] = None  # If None, use current time
+    expected_balance_sats: int
+    expected_balance_fiat: Optional[Decimal] = None
+    fiat_currency: Optional[str] = None
+    tolerance_sats: int = 0
+    tolerance_fiat: Decimal = Decimal("0")

static/js/index.js

@@ -65,7 +65,18 @@ window.app = Vue.createApp({
         loading: false
       },
       manualPaymentRequests: [],
-      pendingExpenses: []
+      pendingExpenses: [],
+      balanceAssertions: [],
+      assertionDialog: {
+        show: false,
+        account_id: '',
+        expected_balance_sats: null,
+        expected_balance_fiat: null,
+        fiat_currency: null,
+        tolerance_sats: 0,
+        tolerance_fiat: 0,
+        loading: false
+      }
     }
   },
   watch: {
@@ -115,6 +126,15 @@ window.app = Vue.createApp({
     },
     pendingManualPaymentRequests() {
       return this.manualPaymentRequests.filter(r => r.status === 'pending')
+    },
+    failedAssertions() {
+      return this.balanceAssertions.filter(a => a.status === 'failed')
+    },
+    passedAssertions() {
+      return this.balanceAssertions.filter(a => a.status === 'passed')
+    },
+    allAccounts() {
+      return this.accounts
     }
   },
   methods: {
@@ -579,6 +599,145 @@ window.app = Vue.createApp({
         LNbits.utils.notifyApiError(error)
       }
     },
+    async loadBalanceAssertions() {
+      if (!this.isSuperUser) return
+
+      try {
+        const response = await LNbits.api.request(
+          'GET',
+          '/castle/api/v1/assertions',
+          this.g.user.wallets[0].adminkey
+        )
+        this.balanceAssertions = response.data
+      } catch (error) {
+        LNbits.utils.notifyApiError(error)
+      }
+    },
+    async submitAssertion() {
+      this.assertionDialog.loading = true
+      try {
+        const payload = {
+          account_id: this.assertionDialog.account_id,
+          expected_balance_sats: this.assertionDialog.expected_balance_sats,
+          tolerance_sats: this.assertionDialog.tolerance_sats || 0
+        }
+
+        // Add fiat balance check if currency selected
+        if (this.assertionDialog.fiat_currency) {
+          payload.fiat_currency = this.assertionDialog.fiat_currency
+          payload.expected_balance_fiat = this.assertionDialog.expected_balance_fiat
+          payload.tolerance_fiat = this.assertionDialog.tolerance_fiat || 0
+        }
+
+        await LNbits.api.request(
+          'POST',
+          '/castle/api/v1/assertions',
+          this.g.user.wallets[0].adminkey,
+          payload
+        )
+
+        this.$q.notify({
+          type: 'positive',
+          message: 'Balance assertion passed!',
+          timeout: 3000
+        })
+
+        // Reset dialog
+        this.assertionDialog = {
+          show: false,
+          account_id: '',
+          expected_balance_sats: null,
+          expected_balance_fiat: null,
+          fiat_currency: null,
+          tolerance_sats: 0,
+          tolerance_fiat: 0,
+          loading: false
+        }
+
+        // Reload assertions
+        await this.loadBalanceAssertions()
+      } catch (error) {
+        // Check if it's a 409 Conflict (assertion failed)
+        if (error.response && error.response.status === 409) {
+          const detail = error.response.data.detail
+          this.$q.notify({
+            type: 'negative',
+            message: `Assertion Failed! Expected: ${this.formatSats(detail.expected_sats)} sats, Got: ${this.formatSats(detail.actual_sats)} sats (diff: ${this.formatSats(detail.difference_sats)} sats)`,
+            timeout: 5000,
+            html: true
+          })
+          // Still reload to show the failed assertion
+          await this.loadBalanceAssertions()
+          this.assertionDialog.show = false
+        } else {
+          LNbits.utils.notifyApiError(error)
+        }
+      } finally {
+        this.assertionDialog.loading = false
+      }
+    },
+    async recheckAssertion(assertionId) {
+      // Set loading state
+      const assertion = this.balanceAssertions.find(a => a.id === assertionId)
+      if (assertion) {
+        this.$set(assertion, 'rechecking', true)
+      }
+
+      try {
+        await LNbits.api.request(
+          'POST',
+          `/castle/api/v1/assertions/${assertionId}/check`,
+          this.g.user.wallets[0].adminkey
+        )
+
+        this.$q.notify({
+          type: 'positive',
+          message: 'Assertion re-checked',
+          timeout: 2000
+        })
+
+        await this.loadBalanceAssertions()
+      } catch (error) {
+        LNbits.utils.notifyApiError(error)
+      } finally {
+        if (assertion) {
+          this.$set(assertion, 'rechecking', false)
+        }
+      }
+    },
+    async deleteAssertion(assertionId) {
+      // Set loading state
+      const assertion = this.balanceAssertions.find(a => a.id === assertionId)
+      if (assertion) {
+        this.$set(assertion, 'deleting', true)
+      }
+
+      try {
+        await LNbits.api.request(
+          'DELETE',
+          `/castle/api/v1/assertions/${assertionId}`,
+          this.g.user.wallets[0].adminkey
+        )
+
+        this.$q.notify({
+          type: 'positive',
+          message: 'Assertion deleted',
+          timeout: 2000
+        })
+
+        await this.loadBalanceAssertions()
+      } catch (error) {
+        LNbits.utils.notifyApiError(error)
+      } finally {
+        if (assertion) {
+          this.$set(assertion, 'deleting', false)
+        }
+      }
+    },
+    getAccountName(accountId) {
+      const account = this.accounts.find(a => a.id === accountId)
+      return account ? account.name : accountId
+    },
     copyToClipboard(text) {
       navigator.clipboard.writeText(text)
       this.$q.notify({
@@ -730,6 +889,7 @@ window.app = Vue.createApp({
     if (this.isSuperUser) {
       await this.loadUsers()
       await this.loadPendingExpenses()
+      await this.loadBalanceAssertions()
     }
   }
 })

templates/castle/index.html

@@ -251,6 +251,136 @@
       </q-card-section>
     </q-card>
 
+    <!-- Balance Assertions (Super User Only) -->
+    <q-card v-if="isSuperUser">
+      <q-card-section>
+        <div class="row items-center justify-between q-mb-md">
+          <h6 class="q-my-none">Balance Assertions</h6>
+          <q-btn
+            size="sm"
+            color="primary"
+            @click="assertionDialog.show = true"
+            icon="add"
+            label="Create Assertion"
+          >
+            <q-tooltip>Create a new balance assertion for reconciliation</q-tooltip>
+          </q-btn>
+        </div>
+
+        <!-- Failed Assertions -->
+        <div v-if="failedAssertions.length > 0" class="q-mb-md">
+          <q-banner class="bg-negative text-white" rounded>
+            <template v-slot:avatar>
+              <q-icon name="error" color="white" />
+            </template>
+            <div class="text-weight-bold">{% raw %}{{ failedAssertions.length }}{% endraw %} Failed Assertion{% raw %}{{ failedAssertions.length > 1 ? 's' : '' }}{% endraw %}</div>
+          </q-banner>
+          <q-list bordered separator class="q-mt-sm">
+            <q-item v-for="assertion in failedAssertions" :key="assertion.id">
+              <q-item-section avatar>
+                <q-icon name="error" color="negative" size="sm">
+                  <q-tooltip>Assertion failed</q-tooltip>
+                </q-icon>
+              </q-item-section>
+              <q-item-section>
+                <q-item-label>Account: {% raw %}{{ getAccountName(assertion.account_id) }}{% endraw %}</q-item-label>
+                <q-item-label caption>Expected: {% raw %}{{ formatSats(assertion.expected_balance_sats) }}{% endraw %} sats</q-item-label>
+                <q-item-label caption>Actual: {% raw %}{{ formatSats(assertion.checked_balance_sats) }}{% endraw %} sats</q-item-label>
+                <q-item-label caption class="text-negative">Difference: {% raw %}{{ formatSats(assertion.difference_sats) }}{% endraw %} sats</q-item-label>
+                <q-item-label caption v-if="assertion.fiat_currency">
+                  Expected: {% raw %}{{ assertion.expected_balance_fiat }} {{ assertion.fiat_currency }}{% endraw %} |
+                  Actual: {% raw %}{{ assertion.checked_balance_fiat }} {{ assertion.fiat_currency }}{% endraw %} |
+                  Difference: {% raw %}{{ assertion.difference_fiat }} {{ assertion.fiat_currency }}{% endraw %}
+                </q-item-label>
+                <q-item-label caption>Checked: {% raw %}{{ formatDate(assertion.checked_at) }}{% endraw %}</q-item-label>
+              </q-item-section>
+              <q-item-section side>
+                <div class="q-gutter-xs">
+                  <q-btn
+                    size="sm"
+                    flat
+                    round
+                    icon="refresh"
+                    @click="recheckAssertion(assertion.id)"
+                    :loading="assertion.rechecking"
+                  >
+                    <q-tooltip>Re-check assertion</q-tooltip>
+                  </q-btn>
+                  <q-btn
+                    size="sm"
+                    flat
+                    round
+                    icon="delete"
+                    @click="deleteAssertion(assertion.id)"
+                    :loading="assertion.deleting"
+                  >
+                    <q-tooltip>Delete assertion</q-tooltip>
+                  </q-btn>
+                </div>
+              </q-item-section>
+            </q-item>
+          </q-list>
+        </div>
+
+        <!-- Passed Assertions -->
+        <div v-if="passedAssertions.length > 0">
+          <q-expansion-item
+            label="Passed Assertions"
+            :caption="`${passedAssertions.length} assertion${passedAssertions.length > 1 ? 's' : ''} passed`"
+            icon="check_circle"
+            header-class="text-positive"
+          >
+            <q-list bordered separator>
+              <q-item v-for="assertion in passedAssertions" :key="assertion.id">
+                <q-item-section avatar>
+                  <q-icon name="check_circle" color="positive" size="sm">
+                    <q-tooltip>Assertion passed</q-tooltip>
+                  </q-icon>
+                </q-item-section>
+                <q-item-section>
+                  <q-item-label>{% raw %}{{ getAccountName(assertion.account_id) }}{% endraw %}</q-item-label>
+                  <q-item-label caption>Balance: {% raw %}{{ formatSats(assertion.checked_balance_sats) }}{% endraw %} sats</q-item-label>
+                  <q-item-label caption v-if="assertion.fiat_currency">
+                    Fiat: {% raw %}{{ assertion.checked_balance_fiat }} {{ assertion.fiat_currency }}{% endraw %}
+                  </q-item-label>
+                  <q-item-label caption>Checked: {% raw %}{{ formatDate(assertion.checked_at) }}{% endraw %}</q-item-label>
+                </q-item-section>
+                <q-item-section side>
+                  <div class="q-gutter-xs">
+                    <q-btn
+                      size="sm"
+                      flat
+                      round
+                      icon="refresh"
+                      @click="recheckAssertion(assertion.id)"
+                      :loading="assertion.rechecking"
+                    >
+                      <q-tooltip>Re-check assertion</q-tooltip>
+                    </q-btn>
+                    <q-btn
+                      size="sm"
+                      flat
+                      round
+                      icon="delete"
+                      @click="deleteAssertion(assertion.id)"
+                      :loading="assertion.deleting"
+                    >
+                      <q-tooltip>Delete assertion</q-tooltip>
+                    </q-btn>
+                  </div>
+                </q-item-section>
+              </q-item>
+            </q-list>
+          </q-expansion-item>
+        </div>
+
+        <!-- No assertions message -->
+        <div v-if="balanceAssertions.length === 0" class="text-center text-grey q-pa-md">
+          No balance assertions yet. Create one to verify your accounting accuracy.
+        </div>
+      </q-card-section>
+    </q-card>
+
     <!-- Quick Actions -->
     <q-card>
       <q-card-section>
@@ -761,4 +891,110 @@
   </q-card>
 </q-dialog>
 
+<!-- Balance Assertion Dialog -->
+<q-dialog v-model="assertionDialog.show" position="top">
+  <q-card v-if="assertionDialog.show" class="q-pa-lg q-pt-xl lnbits__dialog-card">
+    <q-form @submit="submitAssertion" class="q-gutter-md">
+      <div class="text-h6 q-mb-md">Create Balance Assertion</div>
+
+      <div class="text-caption text-grey q-mb-md">
+        Balance assertions help you verify accounting accuracy by checking if an account's actual balance matches your expected balance. If the assertion fails, you'll be alerted to investigate the discrepancy.
+      </div>
+
+      <q-select
+        filled
+        dense
+        v-model="assertionDialog.account_id"
+        :options="allAccounts"
+        option-label="name"
+        option-value="id"
+        emit-value
+        map-options
+        label="Account *"
+        :rules="[val => !!val || 'Account is required']"
+      >
+        <template v-slot:option="scope">
+          <q-item v-bind="scope.itemProps">
+            <q-item-section>
+              <q-item-label>{% raw %}{{ scope.opt.name }}{% endraw %}</q-item-label>
+              <q-item-label caption>{% raw %}{{ scope.opt.account_type }}{% endraw %}</q-item-label>
+            </q-item-section>
+          </q-item>
+        </template>
+      </q-select>
+
+      <q-input
+        filled
+        dense
+        v-model.number="assertionDialog.expected_balance_sats"
+        type="number"
+        label="Expected Balance (sats) *"
+        :rules="[val => val !== null && val !== undefined || 'Expected balance is required']"
+      >
+        <template v-slot:hint>
+          The balance you expect this account to have in satoshis
+        </template>
+      </q-input>
+
+      <q-input
+        filled
+        dense
+        v-model.number="assertionDialog.tolerance_sats"
+        type="number"
+        label="Tolerance (sats)"
+        min="0"
+      >
+        <template v-slot:hint>
+          Allow the actual balance to differ by ± this amount (default: 0)
+        </template>
+      </q-input>
+
+      <q-separator />
+
+      <div class="text-subtitle2">Optional: Fiat Balance Check</div>
+
+      <q-select
+        filled
+        dense
+        v-model="assertionDialog.fiat_currency"
+        :options="currencyOptions"
+        option-label="label"
+        option-value="value"
+        emit-value
+        map-options
+        label="Fiat Currency (optional)"
+        clearable
+      ></q-select>
+
+      <q-input
+        v-if="assertionDialog.fiat_currency"
+        filled
+        dense
+        v-model.number="assertionDialog.expected_balance_fiat"
+        type="number"
+        step="0.01"
+        :label="`Expected Fiat Balance (${assertionDialog.fiat_currency})`"
+      ></q-input>
+
+      <q-input
+        v-if="assertionDialog.fiat_currency"
+        filled
+        dense
+        v-model.number="assertionDialog.tolerance_fiat"
+        type="number"
+        step="0.01"
+        label="Fiat Tolerance"
+        min="0"
+      ></q-input>
+
+      <div class="row q-mt-lg">
+        <q-btn unelevated color="primary" type="submit" :loading="assertionDialog.loading">
+          Create & Check
+        </q-btn>
+        <q-btn v-close-popup flat color="grey" class="q-ml-auto">Cancel</q-btn>
+      </div>
+    </q-form>
+  </q-card>
+</q-dialog>
+
 {% endblock %}

views_api.py

@@ -13,10 +13,13 @@ from lnbits.utils.exchange_rates import allowed_currencies, fiat_amount_as_satos
 
 from .crud import (
     approve_manual_payment_request,
+    check_balance_assertion,
     create_account,
+    create_balance_assertion,
     create_journal_entry,
     create_manual_payment_request,
     db,
+    delete_balance_assertion,
     get_account,
     get_account_balance,
     get_account_by_name,
@@ -26,6 +29,8 @@ from .crud import (
     get_all_manual_payment_requests,
     get_all_user_balances,
     get_all_user_wallet_settings,
+    get_balance_assertion,
+    get_balance_assertions,
     get_journal_entries_by_user,
     get_journal_entry,
     get_manual_payment_request,
@@ -37,8 +42,11 @@ from .crud import (
 from .models import (
     Account,
     AccountType,
+    AssertionStatus,
+    BalanceAssertion,
     CastleSettings,
     CreateAccount,
+    CreateBalanceAssertion,
     CreateEntryLine,
     CreateJournalEntry,
     CreateManualPaymentRequest,
@@ -1051,3 +1059,172 @@ async def api_reject_expense_entry(
 
     # Return updated entry
     return await get_journal_entry(entry_id)
+
+
+# ===== BALANCE ASSERTION ENDPOINTS =====
+
+
+@castle_api_router.post("/api/v1/assertions")
+async def api_create_balance_assertion(
+    data: CreateBalanceAssertion,
+    wallet: WalletTypeInfo = Depends(require_admin_key),
+) -> BalanceAssertion:
+    """
+    Create a balance assertion for reconciliation (admin only).
+    The assertion will be checked immediately upon creation.
+    """
+    from lnbits.settings import settings as lnbits_settings
+
+    if wallet.wallet.user != lnbits_settings.super_user:
+        raise HTTPException(
+            status_code=HTTPStatus.FORBIDDEN,
+            detail="Only super user can create balance assertions",
+        )
+
+    # Verify account exists
+    account = await get_account(data.account_id)
+    if not account:
+        raise HTTPException(
+            status_code=HTTPStatus.NOT_FOUND,
+            detail=f"Account {data.account_id} not found",
+        )
+
+    # Create the assertion
+    assertion = await create_balance_assertion(data, wallet.wallet.user)
+
+    # Check it immediately
+    try:
+        assertion = await check_balance_assertion(assertion.id)
+    except ValueError as e:
+        raise HTTPException(
+            status_code=HTTPStatus.BAD_REQUEST,
+            detail=str(e),
+        )
+
+    # If assertion failed, return 409 Conflict with details
+    if assertion.status == AssertionStatus.FAILED:
+        raise HTTPException(
+            status_code=HTTPStatus.CONFLICT,
+            detail={
+                "message": "Balance assertion failed",
+                "expected_sats": assertion.expected_balance_sats,
+                "actual_sats": assertion.checked_balance_sats,
+                "difference_sats": assertion.difference_sats,
+                "expected_fiat": float(assertion.expected_balance_fiat) if assertion.expected_balance_fiat else None,
+                "actual_fiat": float(assertion.checked_balance_fiat) if assertion.checked_balance_fiat else None,
+                "difference_fiat": float(assertion.difference_fiat) if assertion.difference_fiat else None,
+                "fiat_currency": assertion.fiat_currency,
+            },
+        )
+
+    return assertion
+
+
+@castle_api_router.get("/api/v1/assertions")
+async def api_get_balance_assertions(
+    account_id: str = None,
+    status: str = None,
+    limit: int = 100,
+    wallet: WalletTypeInfo = Depends(require_admin_key),
+) -> list[BalanceAssertion]:
+    """Get balance assertions with optional filters (admin only)"""
+    from lnbits.settings import settings as lnbits_settings
+
+    if wallet.wallet.user != lnbits_settings.super_user:
+        raise HTTPException(
+            status_code=HTTPStatus.FORBIDDEN,
+            detail="Only super user can view balance assertions",
+        )
+
+    # Parse status enum if provided
+    status_enum = None
+    if status:
+        try:
+            status_enum = AssertionStatus(status)
+        except ValueError:
+            raise HTTPException(
+                status_code=HTTPStatus.BAD_REQUEST,
+                detail=f"Invalid status: {status}. Must be one of: pending, passed, failed",
+            )
+
+    return await get_balance_assertions(
+        account_id=account_id,
+        status=status_enum,
+        limit=limit,
+    )
+
+
+@castle_api_router.get("/api/v1/assertions/{assertion_id}")
+async def api_get_balance_assertion(
+    assertion_id: str,
+    wallet: WalletTypeInfo = Depends(require_admin_key),
+) -> BalanceAssertion:
+    """Get a specific balance assertion (admin only)"""
+    from lnbits.settings import settings as lnbits_settings
+
+    if wallet.wallet.user != lnbits_settings.super_user:
+        raise HTTPException(
+            status_code=HTTPStatus.FORBIDDEN,
+            detail="Only super user can view balance assertions",
+        )
+
+    assertion = await get_balance_assertion(assertion_id)
+    if not assertion:
+        raise HTTPException(
+            status_code=HTTPStatus.NOT_FOUND,
+            detail="Balance assertion not found",
+        )
+
+    return assertion
+
+
+@castle_api_router.post("/api/v1/assertions/{assertion_id}/check")
+async def api_check_balance_assertion(
+    assertion_id: str,
+    wallet: WalletTypeInfo = Depends(require_admin_key),
+) -> BalanceAssertion:
+    """Re-check a balance assertion (admin only)"""
+    from lnbits.settings import settings as lnbits_settings
+
+    if wallet.wallet.user != lnbits_settings.super_user:
+        raise HTTPException(
+            status_code=HTTPStatus.FORBIDDEN,
+            detail="Only super user can check balance assertions",
+        )
+
+    try:
+        assertion = await check_balance_assertion(assertion_id)
+    except ValueError as e:
+        raise HTTPException(
+            status_code=HTTPStatus.NOT_FOUND,
+            detail=str(e),
+        )
+
+    return assertion
+
+
+@castle_api_router.delete("/api/v1/assertions/{assertion_id}")
+async def api_delete_balance_assertion(
+    assertion_id: str,
+    wallet: WalletTypeInfo = Depends(require_admin_key),
+) -> dict:
+    """Delete a balance assertion (admin only)"""
+    from lnbits.settings import settings as lnbits_settings
+
+    if wallet.wallet.user != lnbits_settings.super_user:
+        raise HTTPException(
+            status_code=HTTPStatus.FORBIDDEN,
+            detail="Only super user can delete balance assertions",
+        )
+
+    # Verify it exists
+    assertion = await get_balance_assertion(assertion_id)
+    if not assertion:
+        raise HTTPException(
+            status_code=HTTPStatus.NOT_FOUND,
+            detail="Balance assertion not found",
+        )
+
+    await delete_balance_assertion(assertion_id)
+
+    return {"success": True, "message": "Balance assertion deleted"}