feat: implement stability fixes and enhance error handling

src/tests/unit/proxy-retry-mock.test.ts

@@ -0,0 +1,92 @@
+import { describe, it, expect, vi } from 'vitest';
+import { EventEmitter } from 'events';
+import { ProxyService } from '../../server/modules/proxy/proxy.service';
+import { Observable } from 'rxjs';
+
+// Mock dependencies
+const mockTokenManager = { getNextToken: vi.fn(), markAsRateLimited: vi.fn() };
+const mockGeminiClient = { streamGenerateInternal: vi.fn(), generateInternal: vi.fn() };
+
+// Subclass to access private method
+class TestableProxyService extends ProxyService {
+  constructor() {
+    super(mockTokenManager as any, mockGeminiClient as any);
+  }
+
+  public testProcessStream(stream: any, model: string = 'model'): Observable<string> {
+    // Access private method using type assertion
+    return (this as any).processAnthropicInternalStream(stream, model);
+  }
+}
+
+describe('ProxyService Empty Stream Retry Logic', () => {
+  it('should emit error when stream ends without data', async () => {
+    const service = new TestableProxyService();
+    const stream = new EventEmitter();
+
+    const resultObservable = service.testProcessStream(stream);
+
+    let errorReceived: Error | undefined;
+
+    const promise = new Promise<void>((resolve) => {
+      resultObservable.subscribe({
+        next: () => {},
+        error: (err) => {
+          errorReceived = err;
+          resolve();
+        },
+        complete: () => resolve(),
+      });
+    });
+
+    // Simulate empty stream: straight to end
+    setTimeout(() => stream.emit('end'), 10);
+
+    await promise;
+
+    expect(errorReceived).toBeDefined();
+    expect(errorReceived?.message).toBe('Empty response stream');
+  });
+
+  it('should NOT emit error when stream has data', async () => {
+    const service = new TestableProxyService();
+    const stream = new EventEmitter();
+
+    const resultObservable = service.testProcessStream(stream);
+
+    let errorReceived: Error | undefined;
+    const receivedChunks: string[] = [];
+
+    const promise = new Promise<void>((resolve) => {
+      resultObservable.subscribe({
+        next: (c) => receivedChunks.push(c),
+        error: (err) => {
+          errorReceived = err;
+          resolve();
+        },
+        complete: () => resolve(),
+      });
+    });
+
+    // Simulate valid data stream
+    setTimeout(() => {
+      const validJson = JSON.stringify({
+        candidates: [
+          {
+            content: { parts: [{ text: 'hello' }] },
+            finishReason: 'STOP',
+          },
+        ],
+      });
+      stream.emit('data', Buffer.from(`data: ${validJson}\n\n`));
+      stream.emit('end');
+    }, 10);
+
+    await promise;
+
+    expect(errorReceived).toBeUndefined();
+    // It should produce chunks (though exact number depends on mapper logic, at least it shouldn't error)
+    // Actually our mapper might produce "message_start", "content_block_start" etc.
+    // We just care that it didn't error with "Empty response stream"
+  });
+});

src/tests/unit/retry-utils.test.ts

@@ -0,0 +1,59 @@
+import { describe, it, expect } from 'vitest';
+import { applyJitter, calculateRetryDelay } from '../../lib/antigravity/retry-utils';
+
+describe('applyJitter', () => {
+  it('should return values within ±20% range', () => {
+    const baseDelay = 1000;
+    const results: number[] = [];
+
+    for (let i = 0; i < 100; i++) {
+      results.push(applyJitter(baseDelay));
+    }
+
+    // All values should be within 800-1200 range (±20%)
+    results.forEach((r) => {
+      expect(r).toBeGreaterThanOrEqual(800);
+      expect(r).toBeLessThanOrEqual(1200);
+    });
+  });
+
+  it('should produce different values (randomness)', () => {
+    const results = new Set<number>();
+    for (let i = 0; i < 20; i++) {
+      results.add(applyJitter(1000));
+    }
+    // 20 calls should produce multiple distinct values
+    expect(results.size).toBeGreaterThan(5);
+  });
+
+  it('should guarantee minimum value of 1 for small inputs', () => {
+    expect(applyJitter(1)).toBeGreaterThanOrEqual(1);
+    expect(applyJitter(0)).toBe(1);
+  });
+});
+
+describe('calculateRetryDelay', () => {
+  it('should implement exponential backoff', () => {
+    // First attempt (index 0): 1s ± 20% = 800-1200ms
+    const delay0 = calculateRetryDelay(0);
+    expect(delay0).toBeGreaterThanOrEqual(800);
+    expect(delay0).toBeLessThanOrEqual(1200);
+
+    // Second attempt (index 1): 2s ± 20% = 1600-2400ms
+    const delay1 = calculateRetryDelay(1);
+    expect(delay1).toBeGreaterThanOrEqual(1600);
+    expect(delay1).toBeLessThanOrEqual(2400);
+  });
+
+  it('should have maximum delay limit', () => {
+    // Even with high retry count, should not exceed 30s + 20% jitter = 36s
+    const delay = calculateRetryDelay(10);
+    expect(delay).toBeLessThanOrEqual(36000);
+  });
+
+  it('should accept custom base delay', () => {
+    const delay = calculateRetryDelay(0, 500);
+    expect(delay).toBeGreaterThanOrEqual(400); // 500 - 20%
+    expect(delay).toBeLessThanOrEqual(600); // 500 + 20%
+  });
+});

src/tests/unit/signature-utils.test.ts

@@ -0,0 +1,48 @@
+import { describe, it, expect } from 'vitest';
+import { decodeSignature } from '../../lib/antigravity/signature-utils';
+
+describe('decodeSignature', () => {
+  describe('Base64 decoding', () => {
+    it('should correctly decode valid Base64 signature', () => {
+      const original = 'valid-thinking-signature-12345';
+      const base64 = Buffer.from(original).toString('base64');
+      expect(decodeSignature(base64)).toBe(original);
+    });
+
+    it('should decode signature with special characters', () => {
+      const original = 'sig+with/special=chars==';
+      const base64 = Buffer.from(original).toString('base64');
+      expect(decodeSignature(base64)).toBe(original);
+    });
+
+    it('should decode UTF-8 Chinese signature', () => {
+      const original = '思考签名-测试';
+      const base64 = Buffer.from(original).toString('base64');
+      expect(decodeSignature(base64)).toBe(original);
+    });
+  });
+
+  describe('Non-Base64 passthrough', () => {
+    it('should return non-Base64 strings as-is', () => {
+      expect(decodeSignature('plain-text-signature')).toBe('plain-text-signature');
+    });
+
+    it('should handle strings with invalid Base64 characters', () => {
+      expect(decodeSignature('not!valid@base64#')).toBe('not!valid@base64#');
+    });
+  });
+
+  describe('Empty value handling', () => {
+    it('should return undefined for null input', () => {
+      expect(decodeSignature(null)).toBeUndefined();
+    });
+
+    it('should return undefined for undefined input', () => {
+      expect(decodeSignature(undefined)).toBeUndefined();
+    });
+
+    it('should return undefined for empty string', () => {
+      expect(decodeSignature('')).toBeUndefined();
+    });
+  });
+});

src/tests/unit/stream-error-utils.test.ts

@@ -0,0 +1,61 @@
+import { describe, it, expect } from 'vitest';
+import { classifyStreamError, formatErrorForSSE } from '../../lib/antigravity/stream-error-utils';
+
+describe('classifyStreamError', () => {
+  it('should identify timeout errors', () => {
+    const error = new Error('timeout of 30000ms exceeded');
+    const { type, message } = classifyStreamError(error);
+    expect(type).toBe('timeout_error');
+    expect(message).toContain('timed out');
+  });
+
+  it('should identify connection errors', () => {
+    const error = new Error('connect ECONNREFUSED 127.0.0.1:8080');
+    const { type, message } = classifyStreamError(error);
+    expect(type).toBe('connection_error');
+    expect(message).toContain('connect');
+  });
+
+  it('should identify network DNS errors', () => {
+    const error = new Error('getaddrinfo ENOTFOUND googleapis.com');
+    const { type, message } = classifyStreamError(error);
+    expect(type).toBe('network_error');
+    expect(message).toContain('Network');
+  });
+
+  it('should identify socket errors', () => {
+    const error = new Error('socket hang up');
+    const { type, message } = classifyStreamError(error);
+    expect(type).toBe('stream_error');
+    expect(message).toContain('interrupted');
+  });
+
+  it('should return generic message for unknown errors', () => {
+    const error = new Error('some random error');
+    const { type, message } = classifyStreamError(error);
+    expect(type).toBe('unknown_error');
+    expect(message).toBeTruthy();
+    expect(message).toContain('some random error');
+  });
+});
+
+describe('formatErrorForSSE', () => {
+  it('should format as Claude SSE error event', () => {
+    const result = formatErrorForSSE('network_error', 'Network connection failed');
+    expect(result).toContain('event: error');
+    expect(result).toContain('"type":"error"');
+    expect(result).toContain('network_error');
+    expect(result).toContain('Network connection failed');
+  });
+
+  it('should end with newlines', () => {
+    const result = formatErrorForSSE('test', 'test');
+    expect(result.endsWith('\n\n')).toBe(true);
+  });
+
+  it('should be valid SSE format', () => {
+    const result = formatErrorForSSE('timeout_error', 'Request timed out');
+    expect(result.startsWith('event: ')).toBe(true);
+    expect(result).toContain('\ndata: ');
+  });
+});

src/tests/unit/streaming-state.test.ts

@@ -0,0 +1,61 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { StreamingState } from '../../lib/antigravity/ClaudeStreamingMapper';
+
+describe('StreamingState', () => {
+  let state: StreamingState;
+
+  beforeEach(() => {
+    state = new StreamingState();
+  });
+
+  describe('handleParseError', () => {
+    it('should return empty array on first error', () => {
+      const chunks = state.handleParseError('invalid json');
+      expect(chunks).toEqual([]);
+    });
+
+    it('should emit error event when error count exceeds 3', () => {
+      // Simulate 4 parse errors
+      state.handleParseError('error 1');
+      state.handleParseError('error 2');
+      state.handleParseError('error 3');
+      const chunks = state.handleParseError('error 4');
+
+      expect(chunks.length).toBeGreaterThan(0);
+      expect(chunks[0]).toContain('network_error');
+      expect(chunks[0]).toContain('Unstable network');
+    });
+
+    it('should safely close active block on error', () => {
+      // Start a text block first
+      state.startBlock('Text', { type: 'text', text: '' });
+
+      const chunks = state.handleParseError('error during block');
+
+      // Should contain content_block_stop event
+      expect(chunks.some((c) => c.includes('content_block_stop'))).toBe(true);
+    });
+  });
+
+  describe('resetErrorState', () => {
+    it('should reset error counter', () => {
+      state.handleParseError('error 1');
+      state.handleParseError('error 2');
+      state.resetErrorState();
+
+      // After reset, should start counting from 0
+      const chunks = state.handleParseError('error after reset');
+      expect(chunks).toEqual([]);
+    });
+  });
+
+  describe('getErrorCount', () => {
+    it('should return current error count', () => {
+      expect(state.getErrorCount()).toBe(0);
+      state.handleParseError('error 1');
+      expect(state.getErrorCount()).toBe(1);
+      state.handleParseError('error 2');
+      expect(state.getErrorCount()).toBe(2);
+    });
+  });
+});

src/tests/unit/thinking-utils.test.ts

@@ -0,0 +1,90 @@
+import { describe, it, expect } from 'vitest';
+import {
+  hasValidSignature,
+  gracefulDegradeThinking,
+  processThinkingBlocks,
+} from '../../lib/antigravity/thinking-utils';
+
+describe('hasValidSignature', () => {
+  it('should return true for empty thinking + valid signature', () => {
+    const block = { type: 'thinking' as const, thinking: '', signature: 'valid-signature-long' };
+    expect(hasValidSignature(block)).toBe(true);
+  });
+
+  it('should return true for content + long signature', () => {
+    const block = {
+      type: 'thinking' as const,
+      thinking: 'some thought',
+      signature: 'long-enough-signature',
+    };
+    expect(hasValidSignature(block)).toBe(true);
+  });
+
+  it('should return false for content + short signature', () => {
+    const block = { type: 'thinking' as const, thinking: 'some thought', signature: 'short' };
+    expect(hasValidSignature(block)).toBe(false);
+  });
+
+  it('should return false for content + no signature', () => {
+    const block = { type: 'thinking' as const, thinking: 'some thought', signature: undefined };
+    expect(hasValidSignature(block)).toBe(false);
+  });
+
+  it('should return true for non-thinking types', () => {
+    const block = { type: 'text' as const, text: 'hello' };
+    expect(hasValidSignature(block)).toBe(true);
+  });
+});
+
+describe('gracefulDegradeThinking', () => {
+  it('should convert invalid signature thinking to text', () => {
+    const block = { type: 'thinking' as const, thinking: 'important content', signature: 'bad' };
+    const result = gracefulDegradeThinking(block);
+    expect(result?.type).toBe('text');
+    expect((result as any).text).toBe('important content');
+  });
+
+  it('should keep valid thinking block unchanged', () => {
+    const block = {
+      type: 'thinking' as const,
+      thinking: 'content',
+      signature: 'valid-long-signature',
+    };
+    const result = gracefulDegradeThinking(block);
+    expect(result?.type).toBe('thinking');
+  });
+
+  it('should drop empty content + invalid signature block', () => {
+    const block = { type: 'thinking' as const, thinking: '', signature: 'bad' };
+    const result = gracefulDegradeThinking(block);
+    expect(result).toBeNull();
+  });
+
+  it('should keep empty content + valid signature trailing block', () => {
+    const block = { type: 'thinking' as const, thinking: '', signature: 'any-valid-sig' };
+    const result = gracefulDegradeThinking(block);
+    expect(result?.type).toBe('thinking');
+  });
+});
+
+describe('processThinkingBlocks', () => {
+  it('should filter out invalid empty thinking blocks', () => {
+    const blocks = [
+      { type: 'text' as const, text: 'hello' },
+      { type: 'thinking' as const, thinking: '', signature: 'bad' },
+      { type: 'text' as const, text: 'world' },
+    ];
+    const result = processThinkingBlocks(blocks);
+    expect(result.length).toBe(2);
+    expect(result[0].type).toBe('text');
+    expect(result[1].type).toBe('text');
+  });
+
+  it('should convert content with invalid signature to text', () => {
+    const blocks = [{ type: 'thinking' as const, thinking: 'keep me', signature: 'x' }];
+    const result = processThinkingBlocks(blocks);
+    expect(result.length).toBe(1);
+    expect(result[0].type).toBe('text');
+    expect((result[0] as any).text).toBe('keep me');
+  });
+});