claude-session-transcript

Session transcripts are JSONL files under $HOME/.claude/projects/<project-key>/<session-uuid>.jsonl, where the project key is the session-start cwd with slashes replaced by hyphens. In a hook context, use the transcript_path field from the hook's JSON stdin; otherwise pick the most recently modified .jsonl file.

Filter JSONL events where type is "user", userType is "external", and message.content is a string or an array starting with a text element. Then collapse slash-command pairs sharing a promptId and strip wrapper tags like <system-reminder> and <ide_selection>.

The harness injects pseudo-prompts flagged with isMeta: true, such as task notifications, stop-hook feedback, and compaction summaries, which can outnumber real prompts two to one. Drop events that are isMeta and short, or that match known injected shapes like <task-notification> or "This session is being continued".

Active sessions can produce JSONL files of hundreds of megabytes, so avoid unbounded reads. Page through with Read using offset and limit, extract events with jq via Bash, or run wc -l first to gauge the file size.

It does not cover tool-call event extraction, per-skill output formats, or cross-session correlation. Tool_use and tool_result matching rules live in the calling skill such as /learn, and each calling skill decides what to do with the extracted prompts.