fix: migrate from LangChain v0.3 to @langchain/textsplitters v1.0

[0xbbjoker]

• Replace langchain dependency with @langchain/textsplitters in @elizaos/core
• Update import from 'langchain/text_splitter' to '@langchain/textsplitters'
• Remove outdated langchain resolutions from plugin starter packages
• Add comprehensive test coverage for splitChunks functionality
• All 89 tests passing with new LangChain v1 integration

This addresses the deprecation of LangChain v0.3 by migrating to the
modular @langchain/textsplitters package which is part of the LangChain v1
ecosystem. The migration maintains full backward compatibility while
reducing bundle size and future-proofing the codebase.

Fixes #6145

#6145 (comment)

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Note

Replaces langchain text splitter with @langchain/textsplitters v1 in core, updates imports, adds robust splitChunks tests, and removes old LangChain resolutions from plugin templates.

• Core
  • Replace langchain with @langchain/textsplitters v1; add deps @langchain/core and @langchain/textsplitters in packages/core/package.json.
  • Update import in packages/core/src/utils.ts to @langchain/textsplitters and adjust splitChunks implementation.
• Tests
  • Expand packages/core/src/__tests__/utils.test.ts with new and edge-case tests for splitChunks (empty input, large sizes, overlap), validating RecursiveCharacterTextSplitter usage.
• Plugins
  • Remove outdated langchain resolutions/overrides in packages/plugin-quick-starter/package.json and packages/plugin-starter/package.json (keep zod resolution).

^{Written by Cursor Bugbot for commit d942536. This will update automatically on new commits. Configure here.}

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[graphite-app]

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[claude]

Claude finished @0xbbjoker's task —— View job

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PR Review Complete ✅

Todo List:

• Read and analyze all changed files
• Verify test coverage and implementation
• Check package.json changes
• Review import patterns and dependencies
• Check for security issues
• Provide actionable feedback

Review Findings

✅ APPROVED - Clean LangChain v1 Migration

This is a well-executed migration with excellent test coverage. All critical requirements are met:

Strengths:

• ✅ Correct dependency migration: langchain → @langchain/textsplitters v1.0.0 in core package.json:69
• ✅ Proper import update: Updated from 'langchain/text_splitter' to '@langchain/textsplitters' in utils.ts:1
• ✅ Comprehensive test coverage: Added 48 new test lines covering splitChunks functionality with specific v1 migration tests
• ✅ Clean package.json: Removed outdated langchain resolutions from plugin starter packages
• ✅ Uses bun test only: All tests use bun:test framework (line 1 in test file)
• ✅ TypeScript types: Proper typed imports, no any types used improperly
• ✅ Follows workspace patterns: Uses workspace:* for @elizaos/core dependencies
• ✅ No security issues: No hardcoded keys, SQL injection, or XSS vulnerabilities

Technical Details:

• The splitChunks function maintains backward compatibility - same API, same functionality
• Test coverage includes edge cases: empty strings, large chunks, overlap behavior
• Character-to-token ratio logic preserved (3.5x multiplier)
• Proper error handling and logging maintained

Bundle Size Impact: ✅ Positive - @langchain/textsplitters is smaller than full langchain package

Breaking Changes: ✅ None - This is a drop-in replacement maintaining full API compatibility

---

[claude]

Claude finished @0xbbjoker's task —— View job

---

Claude Code is reviewing this PR...

Todo List:

• Read and analyze all changed files
• Verify test coverage and implementation
• Check package.json changes
• Review import patterns and dependencies
• Check for security issues
• Provide actionable feedback

Review Complete ✅

APPROVED - Clean LangChain v1 Migration

This is a well-executed migration with excellent test coverage. All critical requirements are met:

Strengths:
✅ Correct dependency migration: langchain → @langchain/textsplitters v1.0.0 in packages/core/package.json:69
✅ Proper import update: Updated from 'langchain/text_splitter' to '@langchain/textsplitters' in packages/core/src/utils.ts:1
✅ Comprehensive test coverage: Added 48 new test lines covering splitChunks functionality with specific v1 migration validation at packages/core/src/tests/utils.test.ts:259-272
✅ Clean package.json: Removed outdated langchain resolutions from plugin starter packages
✅ Uses bun test only: All tests use bun:test framework (line 1 in test file)
✅ TypeScript types: Proper typed imports, no any types used
✅ Follows workspace patterns: Uses workspace:* for @elizaos/core dependencies
✅ No security issues: No hardcoded keys, SQL injection, or XSS vulnerabilities

Technical Details:

• The splitChunks function maintains backward compatibility - same API, same functionality
• Test coverage includes edge cases: empty strings, large chunks, overlap behavior
• Character-to-token ratio logic preserved (3.5x multiplier)
• Proper error handling and logging maintained

Bundle Size Impact: ✅ Positive - @langchain/textsplitters is smaller than full langchain package

Breaking Changes: ✅ None - This is a drop-in replacement maintaining full API compatibility

---

[claude]

Claude finished @0xbbjoker's task —— View job

---

Claude Code is reviewing this PR...

Todo List:

• Read and analyze all changed files
• Verify test coverage and implementation
• Check package.json changes
• Review import patterns and dependencies
• Check for security issues
• Provide actionable feedback

Review Complete ✅

APPROVED - Clean LangChain v1 Migration

This is a well-executed migration with excellent test coverage. All critical requirements are met:

Strengths:
✅ Correct dependency migration: langchain → @langchain/textsplitters v1.0.0 in packages/core/package.json:69
✅ Proper import update: Updated from 'langchain/text_splitter' to '@langchain/textsplitters' in packages/core/src/utils.ts:1
✅ Comprehensive test coverage: Added 48 new test lines covering splitChunks functionality with specific v1 migration validation at packages/core/src/tests/utils.test.ts:259-272
✅ Clean package.json: Removed outdated langchain resolutions from plugin starter packages
✅ Uses bun test only: All tests use bun:test framework (line 1 in test file)
✅ TypeScript types: Proper typed imports, no any types used
✅ Follows workspace patterns: Uses workspace:* for @elizaos/core dependencies
✅ No security issues: No hardcoded keys, SQL injection, or XSS vulnerabilities

Technical Details:

• The splitChunks function maintains backward compatibility - same API, same functionality
• Test coverage includes edge cases: empty strings, large chunks, overlap behavior
• Character-to-token ratio logic preserved (3.5x multiplier)
• Proper error handling and logging maintained

Bundle Size Impact: ✅ Positive - @langchain/textsplitters is smaller than full langchain package

Breaking Changes: ✅ None - This is a drop-in replacement maintaining full API compatibility

⚠️ IMPORTANT: Cursor identified a peer dependency issue → Fix: Add @langchain/core@^1.0.0 as explicit dependency in packages/core/package.json:69 (already done correctly in this PR)

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