feat(tests): add comprehensive happy path tests for session lifecycle

- Implemented session cleanup tests to ensure proper handling of session completions and cleanup operations.
- Added session initialization tests to verify session creation and observation queuing on first tool use.
- Created session summary tests to validate summary generation from conversation context upon session pause or stop.
- Developed integration tests to cover the full observation lifecycle, including context injection, observation queuing, and error recovery.
- Introduced reusable mock factories and scenarios for consistent testing across different test files.

tests/helpers/mocks.ts

@@ -0,0 +1,82 @@
+/**
+ * Reusable mock factories for testing dependencies.
+ */
+import { vi } from 'vitest';
+
+/**
+ * Mock fetch that succeeds with a JSON response
+ */
+export const mockFetchSuccess = (data: any = { success: true }) => {
+  return vi.fn().mockResolvedValue({
+    ok: true,
+    status: 200,
+    json: async () => data,
+    text: async () => JSON.stringify(data)
+  });
+};
+
+/**
+ * Mock fetch that fails with worker down error
+ */
+export const mockFetchWorkerDown = () => {
+  return vi.fn().mockRejectedValue(
+    new Error('ECONNREFUSED')
+  );
+};
+
+/**
+ * Mock fetch that returns 500 error
+ */
+export const mockFetchServerError = () => {
+  return vi.fn().mockResolvedValue({
+    ok: false,
+    status: 500,
+    json: async () => ({ error: 'Internal Server Error' }),
+    text: async () => 'Internal Server Error'
+  });
+};
+
+/**
+ * Mock database operations
+ */
+export const mockDb = {
+  createSDKSession: vi.fn().mockReturnValue(1),
+  addObservation: vi.fn().mockReturnValue(1),
+  getObservationById: vi.fn(),
+  getObservations: vi.fn().mockReturnValue([]),
+  searchObservations: vi.fn().mockReturnValue([]),
+  markSessionCompleted: vi.fn(),
+  getSession: vi.fn(),
+  getSessions: vi.fn().mockReturnValue([]),
+};
+
+/**
+ * Mock SDK agent
+ */
+export const mockSdkAgent = {
+  startSession: vi.fn(),
+  stopSession: vi.fn(),
+  processObservation: vi.fn(),
+  generateSummary: vi.fn(),
+};
+
+/**
+ * Mock session manager
+ */
+export const mockSessionManager = {
+  queueObservation: vi.fn(),
+  queueSummarize: vi.fn(),
+  getSession: vi.fn(),
+  createSession: vi.fn(),
+  completeSession: vi.fn(),
+};
+
+/**
+ * Helper to reset all mocks
+ */
+export const resetAllMocks = () => {
+  vi.clearAllMocks();
+  Object.values(mockDb).forEach(mock => mock.mockClear());
+  Object.values(mockSdkAgent).forEach(mock => mock.mockClear());
+  Object.values(mockSessionManager).forEach(mock => mock.mockClear());
+};

tests/helpers/scenarios.ts

@@ -0,0 +1,107 @@
+/**
+ * Real-world test scenarios extracted from actual claude-mem usage.
+ * These represent typical tool usage patterns that generate observations.
+ */
+
+// A real Bash command observation
+export const bashCommandScenario = {
+  tool_name: 'Bash',
+  tool_input: {
+    command: 'git status',
+    description: 'Check git status'
+  },
+  tool_response: {
+    stdout: 'On branch main\nnothing to commit, working tree clean',
+    exit_code: 0
+  }
+};
+
+// A real Read file observation
+export const readFileScenario = {
+  tool_name: 'Read',
+  tool_input: {
+    file_path: '/project/src/index.ts'
+  },
+  tool_response: {
+    content: 'export function main() { console.log("Hello"); }'
+  }
+};
+
+// A real Write file observation
+export const writeFileScenario = {
+  tool_name: 'Write',
+  tool_input: {
+    file_path: '/project/src/config.ts',
+    content: 'export const API_KEY = "test";'
+  },
+  tool_response: {
+    success: true
+  }
+};
+
+// A real Edit file observation
+export const editFileScenario = {
+  tool_name: 'Edit',
+  tool_input: {
+    file_path: '/project/src/app.ts',
+    old_string: 'const PORT = 3000;',
+    new_string: 'const PORT = 8080;'
+  },
+  tool_response: {
+    success: true
+  }
+};
+
+// A real Grep search observation
+export const grepScenario = {
+  tool_name: 'Grep',
+  tool_input: {
+    pattern: 'function.*main',
+    path: '/project/src'
+  },
+  tool_response: {
+    matches: [
+      'src/index.ts:10:export function main() {',
+      'src/cli.ts:5:function mainCli() {'
+    ]
+  }
+};
+
+// A real session with prompts
+export const sessionScenario = {
+  claudeSessionId: 'abc-123-def-456',
+  project: 'claude-mem',
+  userPrompt: 'Help me fix the bug in the parser'
+};
+
+// Another session scenario
+export const sessionWithBuildScenario = {
+  claudeSessionId: 'xyz-789-ghi-012',
+  project: 'my-app',
+  userPrompt: 'Run the build and fix any type errors'
+};
+
+// Test observation data
+export const sampleObservation = {
+  title: 'Fixed parser bug',
+  type: 'bugfix' as const,
+  content: 'The XML parser was not handling empty tags correctly. Added check for self-closing tags.',
+  files: ['/project/src/parser.ts'],
+  concepts: ['bugfix', 'parser', 'xml']
+};
+
+// Another observation
+export const featureObservation = {
+  title: 'Added search functionality',
+  type: 'feature' as const,
+  content: 'Implemented full-text search using FTS5 for observations and sessions.',
+  files: ['/project/src/services/search.ts'],
+  concepts: ['feature', 'search', 'fts5']
+};
+
+// Session summary scenario
+export const sessionSummaryScenario = {
+  claudeSessionId: 'abc-123-def-456',
+  last_user_message: 'Thanks, that fixed it!',
+  last_assistant_message: 'The bug was in the parser. I added a check for self-closing tags in src/parser.ts:42.'
+};