Session Title Generator

Observed in: Claude Code internal architecture Variable: SESSION_TITLE_PROMPT Model: Haiku (via queryHaiku) Output Format: JSON ({ "title": "..." })

Purpose

Generates concise, sentence-case session titles (3-7 words) from conversation content. Acts as the single source of truth for AI-generated session titles across all surfaces (SDK, CCR remote sessions, REPL bridge).

System Prompt

Generate a concise, sentence-case title (3-7 words) that captures the main topic or goal of this coding session. The title should be clear enough that the user recognizes the session in a list. Use sentence case: capitalize only the first word and proper nouns.

Return JSON with a single "title" field.

Good examples:
{"title": "Fix login button on mobile"}
{"title": "Add OAuth authentication"}
{"title": "Debug failing CI tests"}
{"title": "Refactor API client error handling"}

Bad (too vague): {"title": "Code changes"}
Bad (too long): {"title": "Investigate and fix the issue where the login button does not respond on mobile devices"}
Bad (wrong case): {"title": "Fix Login Button On Mobile"}

Input Processing

The extractConversationText() function flattens message arrays into a single text string:

• Skips meta and non-human messages
• Tail-slices to the last 1000 characters so recent context wins
• Filters by msg.origin.kind === 'human'

Integration Points

• SDK print path: Non-interactive session title generation
• CCR remote sessions: Interactive session title via useRemoteSession
• REPL bridge: Fire-and-forget title upgrade after 3 user messages