joshualitt · May 18, 2026 · May 12, 2026 · May 13, 2026 · May 13, 2026 · May 13, 2026
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+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { TestRig } from './test-helper.js';
+import * as path from 'node:path';
+import * as fs from 'node:fs';
+import { FinishReason, GenerateContentResponse } from '@google/genai';
+import type { FakeResponse, HistoryTurn } from '@google/gemini-cli-core';
+
+describe('Context Management Fidelity E2E', () => {
+  let rig: TestRig;
+
+  beforeEach(() => {
+    rig = new TestRig();
+  });
+
+  afterEach(async () => await rig.cleanup());
+
+  it('should reproduce the exact context working buffer on resume', async () => {
+    // Mock responses to trigger GC (summarization)
+    const snapshotResponse: FakeResponse = {
+      method: 'generateContent',
+      response: {
+        candidates: [
+          {
+            content: {
+              parts: [
+                {
+                  text: JSON.stringify({
+                    new_facts: ['GC Triggered.'],
+                    new_constraints: [],
+                    new_tasks: [],
+                    resolved_task_ids: [],
+                    obsolete_fact_indices: [],
+                    obsolete_constraint_indices: [],
+                    chronological_summary: 'Snapshot created.',
+                  }),
+                },
+              ],
+              role: 'model',
+            },
+            finishReason: FinishReason.STOP,
+            index: 0,
+          },
+        ],
+      } as unknown as GenerateContentResponse,
+    };
+
+    const countTokensResponse: FakeResponse = {
+      method: 'countTokens',
+      response: { totalTokens: 50000 },
+    };
+
+    const streamResponse = (text: string): FakeResponse => ({
+      method: 'generateContentStream',
+      response: [
+        {
+          candidates: [
+            {
+              content: { parts: [{ text }], role: 'model' },
+              finishReason: FinishReason.STOP,
+              index: 0,
+            },
+          ],
+        },
+      ] as unknown as GenerateContentResponse[],
+    });
+
+    const setupResponses = (fileName: string, mocks: FakeResponse[]) => {
+      const filePath = path.join(rig.testDir!, fileName);
+      fs.writeFileSync(
+        filePath,
+        mocks.map((m) => JSON.stringify(m)).join('\n'),
+      );
+      return filePath;
+    };
+
+    await rig.setup('context-fidelity', {
+      settings: {
+        experimental: {
+          stressTestProfile: true, // Lowers thresholds to trigger GC easily
+        },
+      },
+    });
+
+    const massivePayload = 'X'.repeat(50000);
+    const traceDir = path.join(rig.testDir!, 'traces');
+    fs.mkdirSync(traceDir, { recursive: true });
+    const traceLog = path.join(traceDir, 'trace.log');
+
+    const commonEnv = {
+      GEMINI_API_KEY: 'mock-key',
+      GEMINI_CONTEXT_TRACE_DIR: traceDir,
+      GEMINI_CONTEXT_TRACE_ENABLED: 'true',
+      GEMINI_DEBUG_LOG_FILE: path.join(rig.testDir!, 'debug.log'),
+    };
+
+    const runMocks: FakeResponse[] = [
+      streamResponse('Ack 1'),
+      streamResponse('Ack 2'),
+      streamResponse('Ack 3'),
+      streamResponse('Ack 4'),
+      streamResponse('Ack 5'),
+    ];
+    for (let i = 0; i < 50; i++) {
+      runMocks.push(snapshotResponse);
+      runMocks.push(countTokensResponse);
+    }
+
+    // Turn 1: Initial massive payload to put pressure
+    await rig.run({
+      args: [
+        '--debug',
+        '--fake-responses-non-strict',
+        setupResponses('resp1.json', runMocks),
+      ],
+      stdin: 'Turn 1: ' + massivePayload,
+      env: commonEnv,
+    });
+
+    // Turn 2: Another turn, resuming Turn 1
+    await rig.run({
+      args: [
+        '--debug',
+        '--resume',
+        'latest',
+        '--fake-responses-non-strict',
+        setupResponses('resp2.json', runMocks),
+      ],
+      stdin: 'Turn 2: ' + massivePayload,
+      env: commonEnv,
+    });
+
+    // Turn 3: Third turn to force GC, resuming Turn 2
+    await rig.run({
+      args: [
+        '--debug',
+        '--resume',
+        'latest',
+        '--fake-responses-non-strict',
+        setupResponses('resp3.json', runMocks),
+      ],
+      stdin: 'Turn 3: ' + massivePayload,
+      env: commonEnv,
+    });
+
+    // Extract the rendered context asset from the log
+    const getRenderedContext = (logContent: string): HistoryTurn[] | null => {
+      const lines = logContent.split('\n');
+      const renderLines = lines.filter(
+        (l) =>
+          l.includes('[Render] Render Sanitized Context for LLM') ||
+          l.includes('[Render] Render Context for LLM'),
+      );
+      if (renderLines.length === 0) return null;
+
+      const lastRender = renderLines[renderLines.length - 1];
+      const detailsMatch = lastRender.match(/\| Details: (.*)$/);
+      if (!detailsMatch) return null;
+
+      const details = JSON.parse(detailsMatch[1]);
+      const assetInfo =
+        details.renderedContextSanitized || details.renderedContext;
+      if (assetInfo && assetInfo.$asset) {
+        const assetPath = path.join(traceDir, 'assets', assetInfo.$asset);
+        return JSON.parse(fs.readFileSync(assetPath, 'utf-8'));
+      }
+      return assetInfo;
+    };
+
+    const log1 = fs.readFileSync(traceLog, 'utf-8');
+    const contextBeforeExit = getRenderedContext(log1);
+    expect(contextBeforeExit).toBeDefined();
+    console.log(
+      'Context Before Exit (First 2 turns):',
+      JSON.stringify(contextBeforeExit!.slice(0, 2), null, 2),
+    );
+
+    // Turn 4: Resume and run a small command
+    await rig.run({
+      args: [
+        '--debug',
+        '--resume',
+        'latest',
+        '--fake-responses-non-strict',
+        setupResponses('resp4.json', runMocks),
+        'continue',
+      ],
+      env: commonEnv,
+    });
+
+    const log2 = fs.readFileSync(traceLog, 'utf-8');
+    const contextAfterResume = getRenderedContext(log2);
+    expect(contextAfterResume).toBeDefined();
+    console.log(
+      'Context After Resume (First 2 turns):',
+      JSON.stringify(contextAfterResume!.slice(0, 2), null, 2),
+    );
+
+    expect(contextAfterResume!.length).toBeGreaterThanOrEqual(
+      contextBeforeExit!.length,
+    );
+
+    for (let i = 0; i < contextBeforeExit!.length; i++) {
+      expect(contextAfterResume![i].id).toBe(contextBeforeExit![i].id);
+      expect(contextAfterResume![i].content).toEqual(
+        contextBeforeExit![i].content,
+      );
+    }
+
+    // Most importantly, synthetic IDs (like summaries) must be stable.
+    const syntheticTurns = contextBeforeExit!.filter(
+      (t: HistoryTurn) => t.id && t.id.length === 32,
+    ); // deriveStableId produces 32-char hex
+    expect(syntheticTurns.length).toBeGreaterThan(0);
+
+    const syntheticTurnsAfter = contextAfterResume!.filter(
+      (t: HistoryTurn) => t.id && t.id.length === 32,
+    );
+    expect(syntheticTurnsAfter.length).toBeGreaterThanOrEqual(
+      syntheticTurns.length,
+    );
+
+    // Check if the first synthetic turn is identical
+    expect(syntheticTurnsAfter[0].id).toBe(syntheticTurns[0].id);
+    expect(syntheticTurnsAfter[0].content).toEqual(syntheticTurns[0].content);
+  });
+});
@@ -0,0 +1,149 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { TestRig } from './test-helper.js';
+import * as path from 'node:path';
+import * as fs from 'node:fs';
+import { FinishReason, GenerateContentResponse } from '@google/genai';
+import type { FakeResponse } from '@google/gemini-cli-core';
+
+describe('Context Management Resume E2E', () => {
+  let rig: TestRig;
+
+  beforeEach(() => {
+    rig = new TestRig();
+  });
+
+  afterEach(async () => await rig.cleanup());
+
+  it('should preserve and utilize GC snapshot boundaries when resuming a session', async () => {
+    const snapshotResponse: FakeResponse = {
+      method: 'generateContent',
+      response: {
+        candidates: [
+          {
+            content: {
+              parts: [
+                {
+                  text: JSON.stringify({
+                    new_facts: ['GC Triggered.'],
+                    new_constraints: [],
+                    new_tasks: [],
+                    resolved_task_ids: [],
+                    obsolete_fact_indices: [],
+                    obsolete_constraint_indices: [],
+                    chronological_summary: 'Snapshot created.',
+                  }),
+                },
+              ],
+              role: 'model',
+            },
+            finishReason: FinishReason.STOP,
+            index: 0,
+          },
+        ],
+      } as unknown as GenerateContentResponse,
+    };
+
+    const countTokensResponse: FakeResponse = {
+      method: 'countTokens',
+      response: { totalTokens: 50000 },
+    };
+
+    const streamResponse = (text: string): FakeResponse => ({
+      method: 'generateContentStream',
+      response: [
+        {
+          candidates: [
+            {
+              content: { parts: [{ text }], role: 'model' },
+              finishReason: FinishReason.STOP,
+              index: 0,
+            },
+          ],
+        },
+      ] as unknown as GenerateContentResponse[],
+    });
+
+    const setupResponses = (fileName: string, mocks: FakeResponse[]) => {
+      const filePath = path.join(rig.testDir!, fileName);
+      fs.writeFileSync(
+        filePath,
+        mocks.map((m) => JSON.stringify(m)).join('\n'),
+      );
+      return filePath;
+    };
+
+    await rig.setup('resume-gc-snapshot', {
+      settings: {
+        experimental: {
+          stressTestProfile: true,
+        },
+      },
+    });
+
+    const massivePayload = 'X'.repeat(40000);
+    const logFile = path.join(rig.testDir!, 'debug.log');
+    const traceDir = path.join(rig.testDir!, 'traces');
+    fs.mkdirSync(traceDir, { recursive: true });
+    const traceLog = path.join(traceDir, 'trace.log');
+
+    const commonEnv = {
+      GEMINI_API_KEY: 'mock-key',
+      GEMINI_DEBUG_LOG_FILE: logFile,
+      GEMINI_CONTEXT_TRACE_DIR: traceDir,
+    };
+
+    // Provide a massive pool of responses to prevent exhaustion
+    const runMocks: FakeResponse[] = [streamResponse('Acknowledged block.')];
+    for (let i = 0; i < 50; i++) {
+      runMocks.push(snapshotResponse);
+      runMocks.push(countTokensResponse);
+    }
+
+    // Use stdin for the massive payload to avoid ENAMETOOLONG on Windows
+    await rig.run({
+      args: [
+        '--debug',
+        '--fake-responses-non-strict',
+        setupResponses('resp1.json', runMocks),
+      ],
+      stdin: 'Turn 1: ' + massivePayload,
+      env: commonEnv,
+    });
+
+    await rig.run({
+      args: [
+        '--debug',
+        '--resume',
+        'latest',
+        '--fake-responses-non-strict',
+        setupResponses('resp2.json', runMocks),
+      ],
+      stdin: 'Turn 2: ' + massivePayload,
+      env: commonEnv,
+    });
+
+    const result3 = await rig.run({
+      args: [
+        '--debug',
+        '--resume',
+        'latest',
+        '--fake-responses-non-strict',
+        setupResponses('resp3.json', runMocks),
+        'continue',
+      ],
+      env: commonEnv,
+    });
+
+    expect(result3).toContain('Acknowledged block');
+
+    const traces = fs.readFileSync(traceLog, 'utf-8');
+    expect(traces).toContain('Hitting Synchronous Pressure Barrier');
+    expect(traces).toContain('GC Triggered.');
+  });
+});