Add session summary fields (firstUserPrompt, topics)

[samkeen]

Background

API client feedback requested a way to understand what a session was about without fetching all messages.

Current Behavior

The Session model only includes metadata:

• id, startTime, endTime, messageCount, model, isSubAgent, parentSessionId, subAgentIds

To understand what a session was about, clients must fetch all messages and parse them.

Requested Enhancement

Add summary fields to the Session response:

{
  "id": "499c44ca-...",
  "startTime": "2025-12-30T15:49:17",
  "messageCount": 418,
  "firstUserPrompt": "is this anything of concern in our context...",
  "topics": ["API debugging", "FastAPI", "endpoint routing"]
}

Fields

Field	Description	Implementation
firstUserPrompt	First user message text (truncated)	Extract from first type: "user" message in JSONL
topics	Session topics/themes	TBD - could be extracted from tool names, file paths, or require LLM analysis

Implementation Notes

• firstUserPrompt is straightforward - read first user message from JSONL, truncate to ~200 chars
• topics is more complex:
  • Option A: Derive from tools used + file paths (e.g., "Bash", "api/src/routes")
  • Option B: Simple keyword extraction from messages
  • Option C: LLM-based summarization (expensive, would need caching)

Acceptance Criteria

• firstUserPrompt field added to Session model
• Field populated on list and detail endpoints
• Truncation with ellipsis for long prompts
• Consider topics implementation approach

Related

This was item #3 from client API feedback. Items #1, #2, #4, #5 already exist:

• ✅ Cross-project activity: GET /api/v1/activity/
• ✅ Date range filtering: startDate/endDate params on sessions
• ✅ Flattened content: flatten=true on messages
• ✅ Activity summary: GET /api/v1/activity/summary