diff --git a/__tests__/lib/contract.test.ts b/__tests__/lib/contract.test.ts
new file mode 100644
index 0000000..80b5ea6
--- /dev/null
+++ b/__tests__/lib/contract.test.ts
@@ -0,0 +1,101 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { NETWORKS } from '@/lib/stellar'
+import {
+  cancelStream,
+  createStream,
+  createStreamsBatch,
+  estimateCreateStreamFee,
+  fetchStream,
+  fetchStreamsForAddress,
+  fetchArchivedSentStreamIds,
+  simulateCreateStreamPreview,
+  withdrawFromStream,
+} from '@/lib/contract'
+import type { CreateStreamInput } from '@/types/stream'
+
+const sender = 'GTEST-SENDER'
+const recipient = 'GTEST-RECIPIENT'
+const input: CreateStreamInput = {
+  recipient,
+  token: NETWORKS.testnet.knownTokens[0],
+  totalAmount: 1_000n,
+  startTime: 1_000n,
+  endTime: 2_000n,
+  cliffTime: 1_000n,
+  cliffAmount: 0n,
+}
+
+async function createMockStream() {
+  const promise = createStream(input, sender, 'testnet')
+  await vi.advanceTimersByTimeAsync(700)
+  return promise
+}
+
+describe('contract mock mode', () => {
+  beforeEach(() => {
+    vi.stubEnv('NEXT_PUBLIC_STREAM_CONTRACT_ID_TESTNET', '')
+    vi.useFakeTimers()
+  })
+
+  afterEach(() => {
+    vi.useRealTimers()
+    vi.unstubAllEnvs()
+  })
+
+  it('returns deterministic simulation and fee previews without network calls', async () => {
+    expect((await simulateCreateStreamPreview('testnet', input, sender)).success).toBe(true)
+    await expect(simulateCreateStreamPreview('testnet', input, sender)).resolves.toMatchObject({
+      estimatedFeeXlm: '0.0115',
+      estimatedFeeUsd: '~$0.001',
+      cpuInstructions: 42_000,
+      memoryBytes: 128,
+    })
+    await expect(estimateCreateStreamFee('testnet', input, sender)).resolves.toEqual({
+      minFee: 100_000,
+      estimatedFee: 115_000,
+      estimatedFeeXlm: '0.0115',
+    })
+  })
+
+  it('creates streams in the mock store and queries them by address', async () => {
+    const id = await createMockStream()
+    await expect(fetchStream('testnet', id)).resolves.toMatchObject({
+      id,
+      sender,
+      recipient,
+      depositedAmount: input.totalAmount,
+      withdrawnAmount: 0n,
+      cancelled: false,
+    })
+
+    const streams = await fetchStreamsForAddress('testnet', recipient)
+    expect(streams.some((stream) => stream.id === id)).toBe(true)
+
+    const batchIds = await createStreamsBatch([input, input], sender, 'testnet')
+    expect(batchIds).toHaveLength(2)
+    expect(new Set(batchIds).size).toBe(2)
+  })
+
+  it('updates and cancels streams through the delayed mock write paths', async () => {
+    const id = await createMockStream()
+
+    const withdrawPromise = withdrawFromStream(id, 125n, 'testnet')
+    await vi.advanceTimersByTimeAsync(700)
+    await expect(withdrawPromise).resolves.toBeNull()
+    await expect(fetchStream('testnet', id)).resolves.toMatchObject({ withdrawnAmount: 125n })
+
+    const cancelPromise = cancelStream(id, 'testnet')
+    await vi.advanceTimersByTimeAsync(700)
+    await expect(cancelPromise).resolves.toBeNull()
+    await expect(fetchStream('testnet', id)).resolves.toMatchObject({ cancelled: true })
+  })
+
+  it('returns archived mock stream IDs for a matching sender', async () => {
+    const id = await createMockStream()
+    const cancelPromise = cancelStream(id, 'testnet')
+    await vi.advanceTimersByTimeAsync(700)
+    await cancelPromise
+
+    await expect(fetchArchivedSentStreamIds('testnet', sender)).resolves.toContain(id)
+  })
+})
diff --git a/__tests__/lib/federation.test.ts b/__tests__/lib/federation.test.ts
new file mode 100644
index 0000000..e68ae8b
--- /dev/null
+++ b/__tests__/lib/federation.test.ts
@@ -0,0 +1,53 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { Federation } from '@stellar/stellar-sdk'
+import { FederationLookupError, resolveFederationAddress } from '@/lib/federation'
+
+const accountId = 'GB5XVAABEQMY63WTHDQ5RXADGYF345VWMNPTN2GFUDZT57D57ZQTJ7PS'
+
+describe('resolveFederationAddress', () => {
+  afterEach(() => {
+    vi.restoreAllMocks()
+  })
+
+  it('returns the account and memo data for a successful lookup', async () => {
+    vi.spyOn(Federation.Server, 'resolve').mockResolvedValue({
+      account_id: accountId,
+      memo_type: 'text',
+      memo: 'invoice-42',
+    })
+
+    await expect(resolveFederationAddress('alice*example.com')).resolves.toEqual({
+      federationAddress: 'alice*example.com',
+      accountId,
+      memoType: 'text',
+      memo: 'invoice-42',
+    })
+  })
+
+  it('rejects malformed federation addresses before contacting the resolver', async () => {
+    const resolve = vi.spyOn(Federation.Server, 'resolve')
+    await expect(resolveFederationAddress('not-a-federation-address')).rejects.toMatchObject({
+      name: 'FederationLookupError',
+      message: expect.stringContaining('expected the form'),
+    })
+    expect(resolve).not.toHaveBeenCalled()
+  })
+
+  it('maps a missing federation record to FederationLookupError', async () => {
+    vi.spyOn(Federation.Server, 'resolve').mockRejectedValue(new Error('404 Not Found'))
+
+    const result = resolveFederationAddress('missing*example.com')
+    await expect(result).rejects.toBeInstanceOf(FederationLookupError)
+    await expect(result).rejects.toThrow('No Federation record found')
+  })
+
+  it('rejects a federation response containing an invalid account', async () => {
+    vi.spyOn(Federation.Server, 'resolve').mockResolvedValue({
+      account_id: 'not-a-stellar-account',
+    })
+
+    await expect(resolveFederationAddress('alice*example.com')).rejects.toThrow(
+      'returned an invalid account',
+    )
+  })
+})
diff --git a/__tests__/lib/hidden-streams.test.ts b/__tests__/lib/hidden-streams.test.ts
new file mode 100644
index 0000000..50fbdb8
--- /dev/null
+++ b/__tests__/lib/hidden-streams.test.ts
@@ -0,0 +1,74 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import {
+  blockSender,
+  getBlockedSenders,
+  getHiddenStreamIds,
+  hideStream,
+  subscribeHiddenStreams,
+  unblockSender,
+  unhideStream,
+} from '@/lib/hidden-streams'
+
+describe('hidden streams', () => {
+  beforeEach(() => {
+    localStorage.clear()
+  })
+
+  afterEach(() => {
+    vi.unstubAllGlobals()
+  })
+
+  it('hides and unhides stream IDs idempotently', () => {
+    hideStream('stream-1')
+    hideStream('stream-1')
+    expect(getHiddenStreamIds()).toEqual(new Set(['stream-1']))
+
+    unhideStream('stream-1')
+    unhideStream('stream-1')
+    expect(getHiddenStreamIds()).toEqual(new Set())
+  })
+
+  it('blocks and unblocks sender addresses idempotently', () => {
+    blockSender('G SENDER 1')
+    blockSender('G SENDER 1')
+    expect(getBlockedSenders()).toEqual(new Set(['G SENDER 1']))
+
+    unblockSender('G SENDER 1')
+    unblockSender('G SENDER 1')
+    expect(getBlockedSenders()).toEqual(new Set())
+  })
+
+  it('notifies subscribers only when a persisted set changes', () => {
+    const listener = vi.fn()
+    const unsubscribe = subscribeHiddenStreams(listener)
+
+    hideStream('stream-1')
+    hideStream('stream-1')
+    unhideStream('stream-1')
+    unhideStream('stream-1')
+    blockSender('G SENDER')
+    unblockSender('G SENDER')
+
+    expect(listener).toHaveBeenCalledTimes(4)
+    unsubscribe()
+    hideStream('stream-2')
+    expect(listener).toHaveBeenCalledTimes(4)
+  })
+
+  it('returns empty sets and does not throw when window is unavailable', () => {
+    vi.stubGlobal('window', undefined)
+
+    expect(getHiddenStreamIds()).toEqual(new Set())
+    expect(getBlockedSenders()).toEqual(new Set())
+    expect(() => hideStream('stream-1')).not.toThrow()
+    expect(() => blockSender('G SENDER')).not.toThrow()
+  })
+
+  it('ignores malformed stored JSON', () => {
+    localStorage.setItem('flowstar:hidden-streams', '{bad json')
+    localStorage.setItem('flowstar:blocked-senders', JSON.stringify({ sender: true }))
+
+    expect(getHiddenStreamIds()).toEqual(new Set())
+    expect(getBlockedSenders()).toEqual(new Set())
+  })
+})
diff --git a/__tests__/lib/streams-cache.test.ts b/__tests__/lib/streams-cache.test.ts
new file mode 100644
index 0000000..9abc778
--- /dev/null
+++ b/__tests__/lib/streams-cache.test.ts
@@ -0,0 +1,65 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { readCachedStreams, writeCachedStreams } from '@/lib/streams-cache'
+import type { StreamData } from '@/types/stream'
+
+const stream: StreamData = {
+  id: '42',
+  sender: 'G SENDER',
+  recipient: 'G RECIPIENT',
+  token: { address: 'C TOKEN', symbol: 'TKN', decimals: 7 },
+  depositedAmount: 1000n,
+  withdrawnAmount: 25n,
+  startTime: 100n,
+  endTime: 200n,
+  cliffTime: 100n,
+  cliffAmount: 0n,
+  amountPerSecond: 10n,
+  linearAmount: 1000n,
+  duration: 100n,
+  cancelled: false,
+}
+
+describe('streams cache', () => {
+  beforeEach(() => {
+    localStorage.clear()
+    vi.useFakeTimers()
+    vi.setSystemTime(new Date('2026-01-01T00:00:00.000Z'))
+  })
+
+  afterEach(() => {
+    vi.useRealTimers()
+    vi.unstubAllGlobals()
+  })
+
+  it('writes and reads streams with bigint fields restored', () => {
+    writeCachedStreams('testnet', 'G ADDRESS', [stream])
+
+    expect(readCachedStreams('testnet', 'G ADDRESS')).toEqual({
+      streams: [stream],
+      fetchedAt: new Date('2026-01-01T00:00:00.000Z').getTime(),
+    })
+    expect(readCachedStreams('mainnet', 'G ADDRESS')).toBeNull()
+  })
+
+  it('preserves the original fetchedAt so callers can detect stale data', () => {
+    writeCachedStreams('testnet', 'G ADDRESS', [stream])
+    vi.setSystemTime(new Date('2026-01-02T00:00:00.000Z'))
+
+    const cached = readCachedStreams('testnet', 'G ADDRESS')
+    expect(cached?.fetchedAt).toBe(new Date('2026-01-01T00:00:00.000Z').getTime())
+    expect(Date.now() - (cached?.fetchedAt ?? 0)).toBeGreaterThan(24 * 60 * 60 * 1000 - 1)
+  })
+
+  it('returns null and does not throw when window is unavailable', () => {
+    vi.stubGlobal('window', undefined)
+
+    expect(readCachedStreams('testnet', 'G ADDRESS')).toBeNull()
+    expect(() => writeCachedStreams('testnet', 'G ADDRESS', [stream])).not.toThrow()
+  })
+
+  it('returns null for missing or corrupt cache entries', () => {
+    expect(readCachedStreams('testnet', 'G ADDRESS')).toBeNull()
+    localStorage.setItem('flowstar:streams-cache:testnet:G ADDRESS', 'not-json')
+    expect(readCachedStreams('testnet', 'G ADDRESS')).toBeNull()
+  })
+})
diff --git a/hooks/use-webhooks.ts b/hooks/use-webhooks.ts
index 5bfdbdd..aeea361 100644
--- a/hooks/use-webhooks.ts
+++ b/hooks/use-webhooks.ts
@@ -308,6 +308,50 @@ export function useWebhooks(onSaveError?: () => void) {
     async (delivery: WebhookDelivery): Promise<boolean> => {
       const hook = webhooks.find((h) => h.id === delivery.webhookId)
       if (!hook || !delivery.payload) return false
-      const result = await deliverWithRetry(hook.url, delivery.payload)
+      const result = await deliverWithRetry(hook.url, hook.secret, delivery.payload)
 
-/* … truncated 1031 chars — edit only what you need near the top … */
+      const newDelivery: WebhookDelivery = {
+        webhookId: delivery.webhookId,
+        eventType: delivery.eventType,
+        statusCode: result.statusCode,
+        deliveredAt: Date.now(),
+        success: result.success,
+        payload: delivery.payload,
+      }
+      setHistory((prev) => {
+        const next = [newDelivery, ...prev]
+        reportSaveResult(saveHistory(next))
+        return next
+      })
+      return result.success
+    },
+    [webhooks, reportSaveResult],
+  )
+
+  const testWebhook = useCallback(
+    async (id: string): Promise<boolean> => {
+      const hook = webhooks.find((h) => h.id === id)
+      if (!hook) return false
+      const payload = {
+        schema_version: WEBHOOK_SCHEMA_VERSION,
+        event: 'stream.created',
+        timestamp: new Date().toISOString(),
+        data: { stream_id: 0, note: 'FlowStar webhook test' },
+      }
+      const result = await deliverWithRetry(hook.url, hook.secret, payload, 1)
+      return result.success
+    },
+    [webhooks],
+  )
+
+  return {
+    webhooks,
+    history,
+    addWebhook,
+    removeWebhook,
+    toggleWebhook,
+    fireEvent,
+    testWebhook,
+    resendDelivery,
+  }
+}
diff --git a/lib/contract.ts b/lib/contract.ts
index eecdc36..47cfbcb 100644
--- a/lib/contract.ts
+++ b/lib/contract.ts
@@ -360,14 +360,14 @@ export async function simulateCreateStreamPreview(
     const estimatedFee = Math.ceil(minFee * FEE_BUFFER)
     const feeXlm = (estimatedFee / 1e7).toFixed(4)
     const feeUsd = `~$${((estimatedFee / 1e7) * 0.08).toFixed(4)}`
-    const resources = successSim.transactionData.build().resources()
+    const resources = successSim.transactionData.build().resources
 
     return {
       success: true,
       estimatedFeeXlm: feeXlm,
       estimatedFeeUsd: feeUsd,
-      cpuInstructions: resources.instructions(),
-      memoryBytes: resources.readBytes() + resources.writeBytes(),
+      cpuInstructions: resources.instructions,
+      memoryBytes: resources.diskReadBytes + resources.writeBytes,
     }
   } catch (err) {
     return {