feat: Conflict detection for contradicting decisions

[github-actions[bot]]

Originally posted as issue #268 by @informatJonas
#268

Summary

Detect and warn when new decisions or implementations contradict earlier documented decisions.

Problem

Over time, developers make architectural decisions that get documented as observations. Later, they might:

• Forget about earlier decisions
• Accidentally implement something that contradicts a previous choice
• Not realize a new pattern conflicts with established conventions

Currently, claude-mem doesn't detect these conflicts.

Proposed Solution

1. Decision Tracking Enhancement

Tag observations with decision categories:

• Architecture patterns (e.g., "use repository pattern", "avoid global state")
• Technology choices (e.g., "use PostgreSQL", "prefer REST over GraphQL")
• Code conventions (e.g., "no abbreviations in variable names")
• Security policies (e.g., "always validate input at boundaries")

2. Conflict Detection Engine

When a new observation is created, compare against existing decisions:

New observation: "Added global state manager for user preferences"

⚠️ Potential conflict detected:
   Decision from 2025-11-15: "Avoid global state, use dependency injection"
   Session: "Refactoring auth module"
   
   Options:
   - This supersedes the old decision
   - This is an exception (document why)
   - Cancel and reconsider approach

3. Semantic Similarity

Use vector embeddings to detect semantic conflicts, not just keyword matches:

• "Use composition over inheritance" vs "Extended BaseController class"
• "Keep functions pure" vs "Added side effect to calculate total"

4. Conflict Resolution

Store resolution metadata:

{
  "observation_id": 456,
  "conflicts_with": 123,
  "resolution": "supersedes",
  "reason": "Requirements changed, global state now acceptable for this use case"
}

Use Cases

1. Architectural Consistency: Catch drift from established patterns
2. Team Alignment: Ensure decisions are followed across sessions
3. Decision History: Track why decisions evolved over time
4. Code Review Aid: Surface conflicts before they become tech debt

Implementation Notes

• Could use Chroma embeddings for semantic comparison
• Threshold configuration for conflict sensitivity
• Option to disable for specific observation types

🤖 Generated with Claude Code