fix: Filter out disabled AI Agent tool parents when mapping connected tools

[Dom-Tursini]

Summary

This fixes a tool/source-node desync in getConnectedTools() for AI Agent tool connections when disabled AI tool nodes remain connected.

Previously, toolkitConnections excluded disabled AI tool nodes, while parentNodes still included them. Because the helper correlates both arrays by index, disabling any AI tool node caused later tools to receive the wrong sourceNodeName.

This change filters disabled nodes out of parentNodes so both arrays use the same active-node set and stay index-aligned.

A regression test was added to cover the case where a disabled tool node appears between active tool connections.

How to test:

1. Create an AI Agent with multiple connected AI tool nodes.
2. Disable one tool node that is not the last in the connection order.
3. On the affected code path, later tools are mapped to the wrong sourceNodeName.
4. Verify with this change that later tools remain mapped to the correct source node.
5. Run pnpm test -- utils/tests/helpers.test.ts --runInBand in packages/@n8n/nodes-langchain.

Related Linear tickets, Github issues, and Community forum posts

#26356

Review / Merge checklist

• I have seen this code, I have run this code, and I take responsibility for this code.
• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with Backport to Beta, Backport to Stable, or Backport to v1 (if the PR is an urgent fix that needs to be backported)

[CLAassistant]

All committers have signed the CLA.

[cubic-dev-ai]

No issues found across 2 files

Architecture diagram

sequenceDiagram
    participant Agent as AI Agent Node
    participant Helper as getConnectedTools()
    participant Context as n8n Workflow Context

    Note over Agent,Context: Tool Connection Mapping Flow

    Agent->>Helper: Invoke tool resolution
    
    Helper->>Context: getInputConnectionData(AiTool)
    Context-->>Helper: toolkitConnections (Active tool objects)

    Helper->>Context: getParentNodes(currentNode, AiTool)
    Context-->>Helper: parentNodes (All connected nodes)

    rect rgb(240, 240, 240)
        Note over Helper: Fix: Prevent index desync
        Helper->>Helper: NEW: Filter out nodes where disabled === true
    end

    loop For each tool in toolkitConnections
        Helper->>Helper: CHANGED: Map tool to parentNode by matching index
        Note right of Helper: Correlation relies on identical list lengths
    end

    Helper-->>Agent: Return tools with correct sourceNodeName metadata

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[Dom-Tursini]

Closing this as the fix has been merged via #29460 by @schrothbn . I’m glad to see the index-desync I identified here was resolved using the same logic. Hopefully, the regression tests I included here can still be useful for the core team.