diff --git a/__tests__/api/story-log.test.ts b/__tests__/api/story-log.test.ts
index 3800e71..5dec0b1 100644
--- a/__tests__/api/story-log.test.ts
+++ b/__tests__/api/story-log.test.ts
@@ -25,6 +25,9 @@ const mockPrisma = prisma as unknown as {
 }
 const mockAuth = authenticateApiRequest as ReturnType<typeof vi.fn>
 
+const STORY = { id: 'story-1', product_id: 'prod-1' }
+const LOG_RESULT = { id: 'log-1', created_at: new Date('2026-04-30T10:00:00Z') }
+
 function makeRequest(body: unknown, storyId = 'story-1'): [Request, { params: Promise<{ id: string }> }] {
   return [
     new Request(`http://localhost/api/stories/${storyId}/log`, {
@@ -39,56 +42,144 @@ function makeRequest(body: unknown, storyId = 'story-1'): [Request, { params: Pr
 describe('POST /api/stories/:id/log', () => {
   beforeEach(() => {
     vi.clearAllMocks()
+    mockAuth.mockResolvedValue({ userId: 'user-1', isDemo: false })
+    mockPrisma.story.findFirst.mockResolvedValue(STORY)
+    mockPrisma.storyLog.create.mockResolvedValue(LOG_RESULT)
   })
 
-  // TC-L-01
-  it.todo('returns 401 when no token provided')
-
-  // TC-L-03
-  it.todo('returns 403 for demo users')
-
-  // TC-L-04
-  it.todo('returns 404 when story is not found')
-
-  // TC-L-05
-  it.todo('returns 404 for another user\'s story')
-
   // TC-L-06
-  it.todo('returns 400 when type field is missing')
+  it('returns 400 when type field is missing', async () => {
+    const res = await postStoryLog(...makeRequest({ content: 'Missing type' }))
+    expect(res.status).toBe(400)
+  })
 
   // TC-L-07
-  it.todo('returns 400 for unknown type value')
+  it('returns 400 for unknown type value', async () => {
+    const res = await postStoryLog(...makeRequest({ type: 'UNKNOWN', content: 'test' }))
+    expect(res.status).toBe(400)
+  })
 
   describe('type: IMPLEMENTATION_PLAN', () => {
     // TC-L-08
-    it.todo('returns 400 when content is missing')
+    it('returns 400 when content is missing', async () => {
+      const res = await postStoryLog(...makeRequest({ type: 'IMPLEMENTATION_PLAN' }))
+      expect(res.status).toBe(400)
+    })
+
+    it('returns 400 when content is empty string', async () => {
+      const res = await postStoryLog(...makeRequest({ type: 'IMPLEMENTATION_PLAN', content: '' }))
+      expect(res.status).toBe(400)
+    })
 
     // TC-L-09
-    it.todo('creates log entry and returns 201')
+    it('creates log entry and returns 201 with id and created_at', async () => {
+      const res = await postStoryLog(
+        ...makeRequest({ type: 'IMPLEMENTATION_PLAN', content: 'Aanpak: stap 1 implementeer.' })
+      )
+      const data = await res.json()
+
+      expect(res.status).toBe(201)
+      expect(data).toHaveProperty('id', 'log-1')
+      expect(data).toHaveProperty('created_at')
+      expect(mockPrisma.storyLog.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          data: expect.objectContaining({
+            story_id: 'story-1',
+            type: 'IMPLEMENTATION_PLAN',
+            content: 'Aanpak: stap 1 implementeer.',
+          }),
+        })
+      )
+    })
   })
 
   describe('type: TEST_RESULT', () => {
     // TC-L-10
-    it.todo('returns 400 when status is missing')
+    it('returns 400 when status is missing', async () => {
+      const res = await postStoryLog(...makeRequest({ type: 'TEST_RESULT', content: 'Tests done' }))
+      expect(res.status).toBe(400)
+    })
 
     // TC-L-11
-    it.todo('returns 400 for invalid status value')
+    it('returns 400 for invalid status value', async () => {
+      const res = await postStoryLog(
+        ...makeRequest({ type: 'TEST_RESULT', content: 'Tests done', status: 'UNKNOWN' })
+      )
+      expect(res.status).toBe(400)
+    })
 
     // TC-L-12
-    it.todo('creates log entry with status PASSED and returns 201')
+    it('creates log entry with status PASSED and returns 201', async () => {
+      const res = await postStoryLog(
+        ...makeRequest({ type: 'TEST_RESULT', content: 'Alle tests geslaagd.', status: 'PASSED' })
+      )
+      const data = await res.json()
+
+      expect(res.status).toBe(201)
+      expect(data).toHaveProperty('id', 'log-1')
+      expect(mockPrisma.storyLog.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          data: expect.objectContaining({ type: 'TEST_RESULT', status: 'PASSED' }),
+        })
+      )
+    })
 
     // TC-L-13
-    it.todo('creates log entry with status FAILED and returns 201')
+    it('creates log entry with status FAILED and returns 201', async () => {
+      const res = await postStoryLog(
+        ...makeRequest({ type: 'TEST_RESULT', content: 'Test gefaald.', status: 'FAILED' })
+      )
+      const data = await res.json()
+
+      expect(res.status).toBe(201)
+      expect(mockPrisma.storyLog.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          data: expect.objectContaining({ type: 'TEST_RESULT', status: 'FAILED' }),
+        })
+      )
+    })
   })
 
   describe('type: COMMIT', () => {
     // TC-L-14
-    it.todo('returns 400 when commit_hash is missing')
+    it('returns 400 when commit_hash is missing', async () => {
+      const res = await postStoryLog(
+        ...makeRequest({ type: 'COMMIT', content: 'feat: done', commit_message: 'feat: ST-001' })
+      )
+      expect(res.status).toBe(400)
+    })
 
     // TC-L-15
-    it.todo('returns 400 when commit_message is missing')
+    it('returns 400 when commit_message is missing', async () => {
+      const res = await postStoryLog(
+        ...makeRequest({ type: 'COMMIT', content: 'feat: done', commit_hash: 'abc1234' })
+      )
+      expect(res.status).toBe(400)
+    })
 
     // TC-L-16
-    it.todo('creates log entry with commit fields and returns 201')
+    it('creates log entry with commit fields and returns 201', async () => {
+      const res = await postStoryLog(
+        ...makeRequest({
+          type: 'COMMIT',
+          content: 'feat: implementatie afgerond',
+          commit_hash: 'abc1234',
+          commit_message: 'feat(ST-001): account aanmaken',
+        })
+      )
+      const data = await res.json()
+
+      expect(res.status).toBe(201)
+      expect(data).toHaveProperty('id', 'log-1')
+      expect(mockPrisma.storyLog.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          data: expect.objectContaining({
+            type: 'COMMIT',
+            commit_hash: 'abc1234',
+            commit_message: 'feat(ST-001): account aanmaken',
+          }),
+        })
+      )
+    })
   })
 })