smart-support/docs/phases/phase-4-dev-log.md

Phase 4: Conversation Replay + Analytics -- Development Log

Status: COMPLETED Phase branch: phase-4/analytics-replay Date started: 2026-03-31 Date completed: 2026-03-31 Related plan section: Phase 4 in DEVELOPMENT-PLAN

What Was Built

• Replay data models (StepType enum, ReplayStep, ReplayPage frozen dataclasses)
• Checkpoint transformer converting PostgresSaver JSONB to structured timeline steps
• Replay API: GET /api/conversations (paginated list), GET /api/replay/{thread_id} (paginated timeline)
• Analytics data models (AgentUsage, InterruptStats, AnalyticsResult)
• Analytics event recorder with Protocol interface (PostgresAnalyticsRecorder + NoOpAnalyticsRecorder)
• Analytics queries: resolution_rate, agent_usage, escalation_rate, cost_per_conversation, interrupt_stats
• Analytics API: GET /api/analytics?range=Xd with envelope response
• DB migration: analytics_events table + conversations column additions (resolution_type, agents_used, turn_count, ended_at)

Code Structure

New files created:

File	Purpose	Lines
app/replay/__init__.py	Module entry	2
app/replay/models.py	StepType enum, ReplayStep, ReplayPage	~80
app/replay/transformer.py	Checkpoint JSONB -> ReplayStep[]	~120
app/replay/api.py	FastAPI router /api/replay + /api/conversations	~80
app/analytics/__init__.py	Module entry	2
app/analytics/models.py	AgentUsage, InterruptStats, AnalyticsResult	~55
app/analytics/event_recorder.py	AnalyticsRecorder Protocol + implementations	~40
app/analytics/queries.py	SQL query functions + get_analytics aggregator	~130
app/analytics/api.py	FastAPI router /api/analytics	~50

Modified files:

• app/db.py -- Added analytics_events DDL + conversations migration
• app/main.py -- Wired replay + analytics routers, registered NoOpAnalyticsRecorder

Test files (74 new tests):

• tests/unit/replay/test_models.py
• tests/unit/replay/test_transformer.py
• tests/unit/replay/test_api.py
• tests/unit/analytics/test_models.py
• tests/unit/analytics/test_event_recorder.py
• tests/unit/analytics/test_queries.py
• tests/unit/analytics/test_api.py
• tests/unit/test_db_phase4.py

Test Coverage

• 399 total tests passing (74 new + 325 existing)
• Overall coverage: 92.87% (requirement: 80%)

Per-module coverage:

• replay/models.py: 100%
• replay/transformer.py: 82%
• replay/api.py: 100%
• analytics/models.py: 100%
• analytics/event_recorder.py: 100%
• analytics/queries.py: 81%
• analytics/api.py: 100%

Deviations from Plan

1. Frontend UI deferred: React pages (ReplayListPage, ReplayPage, DashboardPage) not implemented. Backend APIs are complete and testable.
2. ws_handler event recording deferred: Analytics event recording from WebSocket handler not wired yet (NoOpAnalyticsRecorder registered). Actual recording to be done in Phase 5.
3. conversations.agents_used not populated yet: Column added but not populated by existing ws_handler. Backfill logic deferred to Phase 5.

Known Issues / Tech Debt

• Frontend pages need implementation (React Router, ReplayTimeline component)
• WebSocket handler needs to record analytics events via PostgresAnalyticsRecorder
• conversations.agents_used TEXT[] column needs population logic
• Checkpoint transformer depends on LangGraph JSONB structure -- may need version adaptation
• No auth on replay/analytics endpoints (same as Phase 3 -- Phase 5 concern)