test: add unit tests for InsightBuilder and MemoryExporterHook (zero coverage)

[acailic]

Problem

Two classes in agent_debugger_sdk/core/exporters/ have zero test coverage:

• InsightBuilder (agent_debugger_sdk/core/exporters/insights.py) — builds TraceInsight from session data, analysis, and entity extraction
• MemoryExporterHook (agent_debugger_sdk/core/exporters/pipeline.py) — async hook that drives InsightBuilder and calls exporter.export() on session end

Neither class is referenced anywhere in tests/. The existing test_memory_exporters.py covers the exporter schemas and file exporter but not the insight building or pipeline hook logic.

Scope

Add unit tests covering:

InsightBuilder

• build_insight() returns a valid TraceInsight with correct session_digest, failure_patterns, entity_summaries, and metadata
• _build_session_digest() maps session fields correctly
• _build_failure_patterns() sorts by count descending, caps at 20, extracts error types from fingerprints
• _build_entity_summaries() returns empty list on None, maps entity types, caps top_entities at 5

MemoryExporterHook

• on_session_end() does nothing when exporter is None
• on_session_end() skips export when export_on_completion=True and session is not completed
• on_session_end() calls exporter.export() when session is completed
• on_session_end() always exports when export_on_update=True regardless of status
• on_session_end() swallows exceptions from exporter (logs error, does not raise)
• create_memory_exporter_hook() returns a MemoryExporterHook with correct config

Files to create

• tests/test_insight_builder.py

Labels

auto-work