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Luong NGUYEN
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Bumps tutorial coverage from the v2.1.217 baseline (2026-07-22 sync) to v2.1.220 — three contiguous releases (v2.1.218–v2.1.220). Critical fixes: - Nested subagent spawning is on by default again at depth 3 (v2.1.219). Five locations across 04-subagents, CATALOG, 10-cli and QUICK_REFERENCE stated it was disabled by default — true for v2.1.217–v2.1.218 only. CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH=1 now disables rather than enables. All five carry an identical three-era history note. - Claude Opus 5 is the default Opus model (v2.1.219). 10-cli asserted "Opus 4.8 remains the default"; Opus 5 was absent from every model table. Added to both model tables, 19 Compatible Models footers, and ~20 effort-level enumerations. Also fixed: fast-mode model list, auto-mode eligibility self-contradiction in 09-advanced-features, stale CLAUDE_CODE_ENABLE_AUTO_MODE opt-in in CATALOG, hook-event count disagreement (29/30 -> 31 across three files), doc-generator skill name/directory mismatch, stale "May 2026" headings, and the last three docs.anthropic.com links. Added: DirectoryAdded hook, /deep-research explicit-invocation note, /code-review background subagent, context:fork background default, agent frontmatter hook workspace trust, dynamic workflow size guideline and workflowSizeGuideline key, sandbox.network.strictAllowlist, MCP error surfacing, stream-json nested subagent forwarding, frontmatter boolean values, agent name ':' rejection, auto/plan-mode classifier changes, and Opus 5 safety-classifier fallback. Renamed the deep-research skill example to topic-research to stop it shadowing the built-in; mirrored to vi/ja/uk. doc-generator rename mirrored to ja/zh/uk.
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Checkpoint Examples
Real-world examples of using checkpoints effectively in Claude Code.
Note: Checkpoints are created automatically with every user prompt. You do not need to manually save them. To rewind, press Esc twice (Esc+Esc) or use /rewind to open the checkpoint browser.
Example 1: Database Migration
Scenario
You need to migrate from MySQL to PostgreSQL but want to explore both a direct migration and a gradual dual-write approach.
Workflow
User: Let's implement a direct migration from MySQL to PostgreSQL
[Checkpoint A created automatically]
Claude: I'll implement the direct migration...
[Changes database driver, updates queries, modifies schema]
User: Run the tests
[Checkpoint B created automatically]
Claude: Running tests...
❌ 15 tests failing - connection pool issues
User: This approach has issues. Let's try the dual-write pattern instead.
[User presses Esc+Esc, selects Checkpoint A, chooses "Restore code and conversation"]
User: Now implement a dual-write pattern where we write to both databases
Claude: I'll implement dual-write migration...
[Implements dual-write layer, gradual migration strategy]
User: Run the tests
Claude: Running tests...
✅ All tests passing
User: The dual-write approach is clearly safer. Let's commit this.
Example 2: Performance Optimization
Scenario
Multiple performance optimization strategies to try.
Workflow
User: Let's optimize the API response time. Current: 450ms
[Checkpoint "Baseline" created automatically]
Claude: I'll add database query caching...
[Implements Redis caching]
User: Run performance tests
Claude: Results: 280ms average response time (38% improvement)
User: Let me try a different approach.
[User presses Esc+Esc, selects "Baseline" checkpoint, chooses "Restore code and conversation"]
User: Try database query optimization instead
Claude: I'll optimize database queries...
[Adds indexes, optimizes N+1 queries]
User: Run performance tests
Claude: Results: 180ms average response time (60% improvement)
User: Let me also try a third approach.
[User presses Esc+Esc, selects "Baseline" checkpoint, chooses "Restore code and conversation"]
User: Try response compression and CDN
Claude: I'll add compression and CDN...
[Implements gzip, sets up CDN]
User: Run performance tests
Claude: Results: 320ms average response time (29% improvement)
User: Query optimization was the best. Let me go back and combine it with caching.
[User presses Esc+Esc, selects the checkpoint after query optimization, chooses "Restore code and conversation"]
User: Now add Redis caching on top of these optimized queries
Claude: [Adds Redis caching on top of optimized queries]
User: Run performance tests
Claude: Results: 95ms average response time (79% improvement) 🎉
User: Perfect! This is the winner. Let's commit this.
Example 3: UI/UX Iteration
Scenario
Trying different layouts for a dashboard.
Workflow
User: Let's redesign the dashboard with a sidebar layout
[Checkpoint "Start" created automatically]
Claude: [Implements sidebar layout]
User: Show me a screenshot
Claude: [Shows screenshot]
User: The sidebar feels cramped. Let's try a top navigation instead.
[User presses Esc+Esc, selects "Start" checkpoint, chooses "Restore code and conversation"]
User: Try a top navigation layout
Claude: [Implements top navigation]
User: Show me a screenshot
Claude: [Shows screenshot]
User: Better, but let's try a card-based grid layout
[User presses Esc+Esc, selects "Start" checkpoint, chooses "Restore code and conversation"]
User: Try a card-based grid layout
Claude: [Implements card grid]
User: Show me a screenshot
Claude: [Shows screenshot]
User: This is great! But can we combine the top nav with the card grid?
[User presses Esc+Esc, selects the checkpoint after the card grid, chooses "Restore code and conversation"]
User: Add top navigation to the card grid layout
Claude: [Adds top navigation to card grid]
User: Perfect! This is the final design.
Example 4: Debugging Session
Scenario
Hunting down a tricky bug with multiple hypotheses.
Workflow
User: There's a memory leak in the application
[Checkpoint "Before debugging" created automatically]
Claude: Let me investigate...
[Analyzes code]
User: I think it's in the event listeners. Let's fix those.
Claude: [Fixes event listener cleanup]
User: Run memory profiler
Claude: Still leaking memory - event listeners weren't the issue
User: Let me go back and try a different hypothesis.
[User presses Esc+Esc, selects "Before debugging" checkpoint, chooses "Restore code and conversation"]
User: Maybe it's the database connections?
Claude: [Implements connection pooling fixes]
User: Run memory profiler
Claude: Still leaking - not the connections either
User: Let me go back and try another angle.
[User presses Esc+Esc, selects "Before debugging" checkpoint, chooses "Restore code and conversation"]
User: Let's check for circular references
Claude: [Finds and fixes circular references in cache]
User: Run memory profiler
Claude: ✅ Memory leak fixed! The circular references in the caching layer were the culprit.
User: Excellent! Let's commit this fix.
Example 5: API Design Evolution
Scenario
Designing a REST API with multiple iterations.
Workflow
User: Create a REST API for our blog platform
[Checkpoint "Before API design" created automatically]
Claude: [Creates basic CRUD API]
User: This is too simple. Let's add pagination and filtering
Claude: [Adds pagination and filtering]
User: We need better resource relationships
Claude: [Implements HATEOAS links]
User: Actually, let's try GraphQL instead of REST
[User presses Esc+Esc, selects "Before API design" checkpoint, chooses "Restore code and conversation"]
User: Implement a GraphQL API for our blog platform instead
Claude: [Implements GraphQL API]
User: I think REST is better for our use case.
[User presses Esc+Esc, selects the checkpoint after HATEOAS, chooses "Restore code and conversation"]
User: Let's finalize the REST approach.
Example 6: Configuration Management
Scenario
Testing different configuration approaches.
Workflow
User: Move configuration to environment variables
[Checkpoint "Original config" created automatically]
Claude: [Implements env var configuration]
User: Test in development
Claude: Works locally but deployment issues in production
User: Let me try a different approach.
[User presses Esc+Esc, selects "Original config" checkpoint, chooses "Restore code and conversation"]
User: Try a config file approach with validation
Claude: [Implements YAML config with JSON schema validation]
User: Test in development
Claude: ✅ Works well, good validation errors
User: Can we also support env vars for sensitive values?
Claude: [Adds env var override for secrets]
User: Test deployment
Claude: ✅ All environments working correctly
User: Perfect! This is production-ready.
Example 7: Test Strategy
Scenario
Implementing comprehensive testing.
Workflow
User: Add unit tests for the auth module
[Checkpoint created automatically]
Claude: [Adds Jest unit tests]
User: Run tests
Claude: 45 tests passing, 78% coverage
User: Add integration tests too
Claude: [Adds integration tests]
User: Run tests
Claude: 89 tests passing, 92% coverage, but tests are slow (3 minutes)
User: The tests are too slow. Let's optimize.
Claude: [Optimizes test setup, adds parallel execution]
User: Run tests
Claude: 89 tests passing, 92% coverage, 35 seconds ✅
User: Great! Now add E2E tests for critical paths
Claude: [Adds Playwright E2E tests]
User: Run all tests
Claude: 112 tests passing, 94% coverage, 2 minutes
User: Perfect balance of coverage and speed!
Example 8: Using Summarize from Checkpoint
Scenario
After a long debugging session, you want to condense the conversation while preserving context.
Workflow
User: [After 20+ messages of debugging and exploration]
[User presses Esc+Esc, selects an early checkpoint, chooses "Summarize from here"]
[Optionally provides instructions: "Focus on what we tried and what worked"]
Claude: [Generates a summary of the conversation from that point forward]
[Original messages are preserved in the transcript]
[The summary replaces the visible conversation, reducing context window usage]
User: Now let's continue with the approach that worked.
Key Takeaways
- Checkpoints are automatic: Every user prompt creates a checkpoint -- no manual saving needed
- Use Esc+Esc or /rewind: These are the two ways to access the checkpoint browser
- Choose the right restore option: Restore code, conversation, both, or summarize depending on your needs
- Don't fear experimentation: Checkpoints make it safe to try radical changes
- Combine with git: Use checkpoints for exploration, git for finalized work
- Summarize long sessions: Use "Summarize from here" to keep conversations manageable
Last Updated: July 29, 2026 Claude Code Version: 2.1.220 Sources:
- https://code.claude.com/docs/en/checkpointing
- https://code.claude.com/docs/en/changelog
- https://code.claude.com/docs/en/model-config Compatible Models: Claude Opus 5, Claude Sonnet 5, Claude Sonnet 4.6, Claude Opus 4.8, Claude Haiku 4.5