Offline Impact Evaluator

Validate the proposed stack against the offline requirement captured in architecture-refinement. Identify gaps, assess if the solution is over-engineered, and recommend stack adjustments when needed.

Standalone Usage

Can be invoked directly:

•"Does this stack support session-durable offline?"
•"Evaluate offline capability of Next.js + Supabase"
•"Is this architecture over-engineered for transient offline?"

Prerequisites

Requires:

•Architecture brief with offline_requirement.level
•Stack candidates from candidate-generator

Evaluation Process

Step 1: Map Required vs. Actual Capability

Required Level	Minimum Actual Capability
`none`	No offline logic needed
`transient`	In-memory buffering, retry logic, graceful degradation
`session_durable`	IndexedDB/SQLite, background sync, service worker
`strong_offline_first`	CRDT/event sourcing, conflict resolution, guaranteed sync

Step 2: Assess Each Stack Component

For each candidate, evaluate:

Component	Offline Consideration
Frontend	Service worker support, offline detection, UI graceful degradation
Data Layer	Local storage technology, query capability offline
Sync	Background sync API, conflict resolution strategy
Auth	Token caching, session persistence, refresh handling

Step 3: Gap Analysis

Identify:

•Under-delivery: Required capability not met
•Over-engineering: Unnecessary complexity for the requirement
•Risk areas: Components with weak offline story

Step 4: Recommendations

If gaps exist:

•Recommend component swaps or additions
•Estimate implementation complexity delta
•Flag if cost re-evaluation is needed

Offline Technology Reference

Strategy	Persistence	Sync	Complexity	Use Case
Cache-only	None	None	Low	Static assets, read-only data
IndexedDB	Session+	Manual/BG	Medium	Transactional local data
SQLite (WASM)	Session+	Manual	Medium-High	Complex queries offline
Event Queue	Durable	BG Sync	Medium	Action buffering
CRDT	Durable	Automatic	High	Real-time collaboration, conflict-free

Output Contract

yaml

offline_impact_evaluation:
  stack_id: "<reference>"
  
  requirement:
    level: "<none|transient|session_durable|strong_offline_first>"
    session_close_behavior: "<loses_data|persists_locally>"
    sync_strategy: "<none|background_sync|manual_sync|crdt>"
  
  assessment:
    actual_level: "<none|transient|session_durable|strong_offline_first>"
    components:
      frontend:
        capability: "<level>"
        notes: "<details>"
      data_layer:
        capability: "<level>"
        technology: "<what provides offline>"
      sync:
        capability: "<level>"
        strategy: "<how sync works>"
  
  gap_analysis:
    has_gap: true|false
    gap_description: "<what's missing>"
    over_engineered: true|false
    over_engineering_notes: "<why it's excessive>"
  
  risks:
    - risk: "<risk description>"
      severity: "<low|medium|high>"
      mitigation: "<how to address>"
  
  recommendations:
    - action: "<what to change>"
      component: "<which component>"
      impact:
        cost: "<increase|decrease|same>"
        complexity: "<increase|decrease|same>"
        timeline: "<increase|decrease|same>"
  
  verdict:
    stack_viable: true|false
    requires_stack_change: true|false
    requires_cost_reevaluation: true|false

Example: Gap Analysis

yaml

offline_impact_evaluation:
  stack_id: "next-vercel-supabase"
  
  requirement:
    level: "session_durable"
    session_close_behavior: "persists_locally"
    sync_strategy: "background_sync"
  
  assessment:
    actual_level: "transient"
    components:
      frontend:
        capability: "transient"
        notes: "No service worker configured by default"
      data_layer:
        capability: "none"
        technology: "Server-side only"
      sync:
        capability: "none"
        strategy: "N/A"
  
  gap_analysis:
    has_gap: true
    gap_description: "Stack lacks local persistence and background sync"
    over_engineered: false
  
  risks:
    - risk: "Data loss on network interruption"
      severity: "high"
      mitigation: "Add IndexedDB layer with sync"
  
  recommendations:
    - action: "Add @tanstack/query with offline persistence"
      component: "data_layer"
      impact:
        cost: "same"
        complexity: "increase"
        timeline: "increase"
    - action: "Implement service worker for caching"
      component: "frontend"
      impact:
        cost: "same"
        complexity: "increase"
        timeline: "increase"
  
  verdict:
    stack_viable: true
    requires_stack_change: false
    requires_cost_reevaluation: false

Integration Points

•Invoked by: stack-evaluation (after candidate-generator)
•May trigger: Cost re-evaluation if requires_cost_reevaluation: true
•Feeds into: implementation-plan (offline phase planning)