fix: resolve SplitInBatches output confusion for AI assistants (#97)

## Problem
AI assistants were consistently connecting SplitInBatches node outputs backwards because:
- Output index 0 = "done" (runs after loop completes)
- Output index 1 = "loop" (processes items inside loop)
This counterintuitive ordering caused incorrect workflow connections.

## Solution
Enhanced the n8n-mcp system to expose and clarify output information:

### Database & Schema
- Added `outputs` and `output_names` columns to nodes table
- Updated NodeRepository to store/retrieve output information

### Node Parsing
- Enhanced NodeParser to extract outputs and outputNames from nodes
- Properly handles versioned nodes like SplitInBatchesV3

### MCP Server
- Modified getNodeInfo to return detailed output descriptions
- Added connection guidance for each output
- Special handling for loop nodes (SplitInBatches, IF, Switch)

### Documentation
- Enhanced DocsMapper to inject critical output guidance
- Added warnings about counterintuitive output ordering
- Provides correct connection patterns for loop nodes

### Workflow Validation
- Added validateSplitInBatchesConnection method
- Detects reversed connections and provides specific errors
- Added checkForLoopBack with depth limit to prevent stack overflow
- Smart heuristics to identify likely connection mistakes

## Testing
- Created comprehensive test suite (81 tests)
- Unit tests for all modified components
- Edge case handling for malformed data
- Performance testing with large workflows

## Impact
AI assistants will now:
- See explicit output indices and names (e.g., "Output 0: done")
- Receive clear connection guidance
- Get validation errors when connections are reversed
- Have enhanced documentation explaining the correct pattern

Fixes #97

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/database/node-repository.ts

@@ -22,8 +22,9 @@ export class NodeRepository {
         node_type, package_name, display_name, description,
         category, development_style, is_ai_tool, is_trigger,
         is_webhook, is_versioned, version, documentation,
-        properties_schema, operations, credentials_required
-      ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+        properties_schema, operations, credentials_required,
+        outputs, output_names
+      ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
     `);
     
     stmt.run(
@@ -41,7 +42,9 @@ export class NodeRepository {
       node.documentation || null,
       JSON.stringify(node.properties, null, 2),
       JSON.stringify(node.operations, null, 2),
-      JSON.stringify(node.credentials, null, 2)
+      JSON.stringify(node.credentials, null, 2),
+      node.outputs ? JSON.stringify(node.outputs, null, 2) : null,
+      node.outputNames ? JSON.stringify(node.outputNames, null, 2) : null
     );
   }
   
@@ -70,7 +73,9 @@ export class NodeRepository {
       properties: this.safeJsonParse(row.properties_schema, []),
       operations: this.safeJsonParse(row.operations, []),
       credentials: this.safeJsonParse(row.credentials_required, []),
-      hasDocumentation: !!row.documentation
+      hasDocumentation: !!row.documentation,
+      outputs: row.outputs ? this.safeJsonParse(row.outputs, null) : null,
+      outputNames: row.output_names ? this.safeJsonParse(row.output_names, null) : null
     };
   }
   
@@ -238,7 +243,9 @@ export class NodeRepository {
       properties: this.safeJsonParse(row.properties_schema, []),
       operations: this.safeJsonParse(row.operations, []),
       credentials: this.safeJsonParse(row.credentials_required, []),
-      hasDocumentation: !!row.documentation
+      hasDocumentation: !!row.documentation,
+      outputs: row.outputs ? this.safeJsonParse(row.outputs, null) : null,
+      outputNames: row.output_names ? this.safeJsonParse(row.output_names, null) : null
     };
   }
 }

src/database/schema.sql

@@ -15,6 +15,8 @@ CREATE TABLE IF NOT EXISTS nodes (
   properties_schema TEXT,
   operations TEXT,
   credentials_required TEXT,
+  outputs TEXT, -- JSON array of output definitions
+  output_names TEXT, -- JSON array of output names
   updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
 );