🐛 Bugfix: How to fix the 100% reproducible crash at PLAN phase: enhanc...

Date: 2026-02-23
Time: 18:43:56 UTC
Session: gspace1-138.9
Agent: backend
Confidence: 98%
Status: ✅ Documented

📋 Decision Context

Question:

How to fix the 100% reproducible crash at PLAN phase: enhance.enhancedPrompt.substring is not a function?

Task: S138 fix enhancedPrompt type mismatch crash

🎯 Decision Made

Chosen:

Proper fix: Updated ModuleGenEnhanceResult.enhancedPrompt to union type (EnhancedPromptData | string), added two exported helper functions (getEnhancedPromptTitle, serializeEnhancedPrompt), fixed executor line 159 and analyze phase lines 46+63, updated test mock

Options Considered:

1. Quick fix: defensive typeof check on the .substring() call only
2. Proper fix: update the type, add helper functions, fix all consumers
3. Change the prompt template to return a string instead of an object

💭 Reasoning

Root cause: Three files disagreed about what enhancedPrompt is. The prompt template (system-enhance.prompt.md) instructs the LLM to return an object {title, description, keyFeatures, targetUsers, impliedRequirements}. The TypeScript type said string. The executor called .substring() on it. The analyze phase passed it to a template where it rendered as [object Object]. The proper fix aligns the type with reality (union type for backward compat) and adds reusable helpers: getEnhancedPromptTitle() extracts a display name from either form, serializeEnhancedPrompt() converts the object to a human-readable string for template interpolation. Changing the prompt to return a string (option 3) would lose structured data that could be valuable for future phases. The quick fix (option 1) would leave the analyze phase receiving garbage data.

📁 Files Involved

• apis/backend-vitto-api/src/app/module-generation/module-generation.types.ts
• apis/backend-vitto-api/src/app/module-generation/phases/module-gen-phase.executor.ts
• apis/backend-vitto-api/src/app/module-generation/phases/analyze.phase.ts
• apis/backend-vitto-api/src/app/module-generation/__tests__/phase-executor.spec.ts

🔗 Related

• Decision ID: dev_1771872236083_xa32tbn
• Session: 138
• Workspace: gspace1

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