Agent skill

claude-session-data-schema-reference

Claude Code session log schema — JSONL record types, message structure, tool call/result pairing, subagent file locations, team session layout, task/plan/team configuration paths. Use when parsing ~/.claude/projects/**/*.jsonl files, writing PostToolUse hooks that measure response sizes, building session analyzers, or any agent that reads or queries Claude session transcripts.

View SKILL.md on GitHub Repository
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Install this agent skill to your Project

npx add-skill https://github.com/Jamie-BitFlight/claude_skills/tree/main/plugins/plugin-creator/skills/claude-session-data-schema-reference

SKILL.md

Claude Code Session Log Schema

Reference skill for the JSONL session log format written by Claude Code under ~/.claude/projects/.

All claims in the reference are sourced from direct JSONL file inspection and verified against the LM Assist TypeScript source. No fields are inferred.

When to Load

Load ./references/schema.md when you need:

  • Directory structure and project-key encoding rules
  • Complete record type discriminator (system, user, assistant, result, progress, summary, file-history-snapshot)
  • Field-level schema for each record type
  • Tool call / tool result pairing algorithm
  • Subagent and team session file naming conventions
  • Task, plan, and team configuration paths
  • Hook integration — how PostToolUse tool_response maps to tool_result.content
  • What is NOT in the logs (per-tool token costs, streaming events, hook records, per-tool timing)

Source

Schema verified 2026-03-24. Source reference: ./references/schema.md.

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