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@sharifajahanshaik sharifajahanshaik commented Aug 22, 2025

Pull Request

Description

This pull request contains comprehensive documentation improvements focusing on LangGraph integration and middleware functionality. The changes enhance the developer experience by providing clearer explanations, working code examples, and better organization of documentation content.

Type of Change

  • 🐛 Bug fix (non-breaking change which fixes an issue)
  • ✨ New feature (non-breaking change which adds functionality)
  • 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
  • 📚 Documentation update
  • 🧹 Code refactoring (no functional changes)
  • ⚡ Performance improvement
  • 🧪 Test coverage improvement
  • 🔧 Build/CI configuration change

Related Issues

  • Fixes #
  • Related to #

Changes Made

  • Added LangGraph.md documentation.
  • Also added a example to implement LangGraph

AI Provider Impact

  • OpenAI
  • Anthropic
  • Google AI/Vertex
  • AWS Bedrock
  • Azure OpenAI
  • Hugging Face
  • Ollama
  • Mistral
  • All providers
  • No provider-specific changes

Component Impact

  • CLI
  • SDK
  • MCP Integration
  • Streaming
  • Tool Calling
  • Configuration
  • Documentation
  • Tests

Testing

  • Unit tests added/updated
  • Integration tests added/updated
  • E2E tests added/updated
  • Manual testing performed
  • All existing tests pass

Test Environment

  • OS: macOs
  • Node.js version: v20.19.4
  • Package manager: 10.13.1

Performance Impact

  • No performance impact
  • Performance improvement
  • Minor performance impact (acceptable)
  • Significant performance impact (needs discussion)

Breaking Changes

Screenshots/Demo

Checklist

  • My code follows the project's style guidelines
  • I have performed a self-review of my code
  • I have commented my code, particularly in hard-to-understand areas
  • I have made corresponding changes to the documentation
  • My changes generate no new warnings
  • I have added tests that prove my fix is effective or that my feature works
  • New and existing unit tests pass locally with my changes
  • Any dependent changes have been merged and published

Additional Notes

Summary by CodeRabbit

  • Documentation
    • Added a comprehensive LangGraph guide covering core concepts (graph structure, nodes/edges, state), capabilities (looping/branching, persistence, human-in-the-loop, streaming), JavaScript examples, advanced patterns, and troubleshooting.
    • Corrected an embeddings example to use the proper embed() invocation and clarified result handling/logging.

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Walkthrough

Adds a new LangGraph documentation page with concepts, workflow, examples, and troubleshooting, and fixes a code snippet in LangChain/LangChainComponentImplementation.md by replacing an incomplete VertexAIEmbeddings call with a concrete embed invocation.

Changes

Cohort / File(s) Summary of Changes
Docs — LangChain snippet fix
LangChain/LangChainComponentImplementation.md
Replaces await embeddings. with await embeddings.embed("I like chocolates"); and logs vector.length.
Docs — LangGraph new guide
docs/LangGraph/LangGraph.md
Adds comprehensive documentation covering LangGraph overview, components, state/edges, messages, compilation workflow, basic/advanced usage, and troubleshooting.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  actor User
  participant SG as StateGraph Builder
  participant Compiler
  participant Runtime as Graph Runtime
  participant Node as Node(s)/LLM/Tools

  User->>SG: Define state, nodes, edges
  SG->>Compiler: Compile()
  Compiler-->>SG: Validated graph (START/END, edges)
  User->>Runtime: run(initial_state)
  loop Flow control (conditional/loops)
    Runtime->>Node: Execute node with current state
    Node-->>Runtime: State delta / messages
    Runtime->>Runtime: Reduce & persist state
    alt Human-in-the-loop (optional)
      Runtime-->>User: interruptBefore/After hook
      User-->>Runtime: Resume/modify
    end
  end
  Runtime-->>User: Final state/result
Loading

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

Suggested reviewers

  • murdore

Poem

A nibble of docs, a hop through the graph,
Nodes line up—tap, tap, tap!
States reduce, edges weave tight,
Embeds now hum, vectors just right.
With whiskers twitching, I sign this map—
Onward we bound, graph in our lap! 🐇✨

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Actionable comments posted: 1

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (5)
LangChain/LangChainComponentImplementation.md (5)

5-9: Fix PromptTemplate usage (typos and object syntax).

  • Typo in class name: PromptTemplatelPromptTemplate.
  • Invalid invoke payload: should be { topic: "cats" }.
  • Remove stray character at Line 8.
-import {PromptTemplate} from "@langchain/core/prompts";
-const prompt = PromptTemplatel.fromTemplate("Tell me a joke about {topic}");
-const result = await prompt.invoke({topic} : "cats");
-console.log(result);
+import { PromptTemplate } from "@langchain/core/prompts";
+const prompt = PromptTemplate.fromTemplate("Tell me a joke about {topic}");
+const result = await prompt.invoke({ topic: "cats" });
+console.log(result);

30-37: Fix chaining example (template spacing, call syntax).

  • Add missing space in template placeholder.
  • Fix extra brace/semicolon in chain2.invoke.
  • Log remains correct; res1.content/res2.content matches ChatModel output.
-const prompt1 = PromptTemplate.fromTemplate("Give me 2 states in{country}");
+const prompt1 = PromptTemplate.fromTemplate("Give me 2 states in {country}");
 const prompt2 = PromptTemplate.fromTemplate("Give me 2 places in {state}");
 const chain1 = prompt1.pipe(llm);
 const chain2 = prompt2.pipe(llm);
 const res1 = await chain1.invoke({country: "India"});
-const res2 = await chain2.invoke({state: res1.content};)
-console.log("States: ",res1.content);
-console.log("Places: ",res2.content);
+const res2 = await chain2.invoke({ state: res1.content });
+console.log("States: ", res1.content);
+console.log("Places: ", res2.content);

43-49: Use correct Vertex AI embeddings model id and method name.

  • Model id: "text-embedding-004" (singular), not "text-embeddings-004".
  • Method: use embedQuery(text) for a single string. LCJS exposes embedQuery/embedDocuments, not embed. See official docs. (js.langchain.com)
 import {VertexAIEmbeddings} from "@langchain/google-vertexai";
 const embeddings = new VertexAIEmbeddings({
-model : "text-embeddings-004"
+  model: "text-embedding-004"
 });
-const vector = await embeddings.embed("I like chocolates");
-console.log(vector.length);
+const vector = await embeddings.embedQuery("I like chocolates");
+console.log(vector.length);

54-56: Fix class name and prefer a valid initialization pattern for MemoryVectorStore.

  • Typo: MemoryVectoryStoreMemoryVectorStore.
  • Initialize with the embeddings instance (constructor) so you can add docs later. Both constructor and fromDocuments are supported in LCJS. (v02.api.js.langchain.com)
-import {MemoryVectorStore} from "langchain/vectorstores/memory";
-const vectorstore = new MemoryVectoryStore(embeddings);
+import { MemoryVectorStore } from "langchain/vectorstores/memory";
+const vectorStore = new MemoryVectorStore(embeddings);

61-71: Correct Document import and construction; fix variable names.

  • Import Document (singular).
  • Construct with an object literal.
  • Use vectorStore consistently; the prior snippet defined it in camelCase.
  • Consider passing explicit IDs to avoid accidental duplicates. (js.langchain.com)
-import {Documents} from "@langchain/core/documents";
-const document1 = new Document(
-pageContent: "I like chocolates.";
-metadata:{source: "tweet"},
-)
-const document2 = new Document(
-pageContent: "The weather forecast for tomorrow is cloudy",
-metadata: {source: "news"},
-)
-const documents = [document1, document2]
-await vectorStore.addDocuments(documents)
+import { Document } from "@langchain/core/documents";
+const document1 = new Document({
+  pageContent: "I like chocolates.",
+  metadata: { source: "tweet" },
+});
+const document2 = new Document({
+  pageContent: "The weather forecast for tomorrow is cloudy",
+  metadata: { source: "news" },
+});
+const documents = [document1, document2];
+await vectorStore.addDocuments(documents, { ids: ["doc1", "doc2"] });
🧹 Nitpick comments (6)
LangChain/LangChainComponentImplementation.md (2)

12-19: Clean up ChatPromptTemplate snippet and payload.

  • Remove stray control character at Line 12.
  • The rest of the snippet is fine; keeping the same message tuple format is acceptable in LCJS v0.2+.
-
 import {ChatPromptTemplate} from "@langchain/core/prompts";
 const chatPrompt = ChatPromptTemplate.fromMessages([
   ["system", "You are a funny assistant"],
   ["human", "Tell me a joke about {topic}."]
 ]);
-const chatResult = await chatPrompt.invoke({topic} : "cats");
+const chatResult = await chatPrompt.invoke({ topic: "cats" });
 console.log(chatResult);

75-77: Unify variable name for vector store.

  • Earlier you defined vectorStore (camelCase). Use the same casing here.
-const docs = await vectorstore.similaritySearch(query);
+const docs = await vectorStore.similaritySearch(query);
docs/LangGraph/LangGraph.md (4)

200-243: JS example: align with LangGraph JS API and best practices.

  • Imports and Annotation.Root usage look correct for JS. Confirming StateGraph, Annotation, START, END from @langchain/langgraph. (langchain-ai.github.io)
  • For human-in-the-loop later, note that interrupts require a checkpointer; consider adding a comment to set one when needed. (langchain-ai.github.io)
-import { StateGraph, Annotation, START, END } from "@langchain/langgraph";
+import { StateGraph, Annotation, START, END } from "@langchain/langgraph";
// npm i @langchain/langgraph @langchain/core
@@
-// Compile and execute
+// Compile and execute
 const graph = builder.compile();
@@
 console.log(result);

247-259: Human-in-the-Loop: prefer documented option names and mention checkpointer.

-const workflow = graph.compile({
-  interruptBefore: ["humanReview"],
-  interruptAfter: ["analysis"],
-});
+const workflow = graph.compile({
+  // Requires a checkpointer to persist state during interrupts
+  // checkpointer: new InMemorySaver(), // import from "@langchain/langgraph"
+  interruptBefore: ["humanReview"],
+  interruptAfter: ["analysis"],
+});

83-97: Clarify “State is user-defined…” and contrast to LangChain.

  • The distinction is correct but consider one line showing that state channels are defined via Annotation.Root. This ties the prose to the example. (langchain-ai.github.io)
-State is user-defined and maintained and passed between nodes during execution. When deciding which node to target next, this is the current state that we look at.
+State is user-defined and passed between nodes. In JS, you define state channels with `Annotation.Root({...})`, and LangGraph routes/merges updates via reducers.

160-170: Minor terminology tweak for Messages section.

  • “Uses LangChain BaseMessage subclasses” is accurate; consider linking MessagesAnnotation as a common pattern. (langchain-ai.github.io)
-- Uses LangChain BaseMessage subclasses:
+- Uses LangChain BaseMessage subclasses (see also `MessagesAnnotation` for a ready-made messages state):
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📥 Commits

Reviewing files that changed from the base of the PR and between cc0f79b and c4f966a.

📒 Files selected for processing (2)
  • LangChain/LangChainComponentImplementation.md (1 hunks)
  • docs/LangGraph/LangGraph.md (1 hunks)
🧰 Additional context used
🪛 LanguageTool
docs/LangGraph/LangGraph.md

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LangChain/LangChainComponentImplementation.md

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🪛 markdownlint-cli2 (0.17.2)
docs/LangGraph/LangGraph.md

22-22: Link fragments should be valid

(MD051, link-fragments)


23-23: Link fragments should be valid

(MD051, link-fragments)

@sharifajahanshaik sharifajahanshaik force-pushed the BZ-43484-add-lang-graph-document-to-neurolink branch from c4f966a to fbfcb1b Compare August 22, 2025 06:58
@sharifajahanshaik sharifajahanshaik changed the title docs(longgraph): add langgraph document to Neurolink BZ-43484 docs(langgraph): add langgraph document to Neurolink BZ-43484 Aug 22, 2025
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