session-reader

name	session-reader
description	Efficiently read and analyze pi agent session JSONL files. Use when asked to "read a session", "analyze a session", "what happened in this session", or given a .jsonl session file path.

Read Pi Sessions

Parse pi session JSONL files into readable, structured output. Sessions live in ~/.pi/agent/sessions/<project>/ as .jsonl files.

Step 1: Identify the Session File

Resolve the session file path. Sessions are stored at:

~/.pi/agent/sessions/--<path-with-dashes>--/<timestamp>_<uuid>.jsonl

If the user provides a partial path or project name, find the file:

ls -t ~/.pi/agent/sessions/*<project>*/*.jsonl | head -5

Step 2: Start with an Overview

Always start with the overview to understand the session before diving deeper. Script paths below (scripts/read_session.py, references/session-format.md) are relative to this skill's directory — resolve them against the folder containing this SKILL.md when running the command.

uv run scripts/read_session.py <path> --mode overview

This shows: session metadata (model, project, cost), turn count, and a summary of every turn with timestamps and tool calls used.

Step 3: Read Specific Content

Based on what's needed, use the appropriate mode:

Goal	Command
See user/assistant conversation only	--mode conversation
See everything including tool I/O	--mode full
See what tools were called and results	--mode tools
Analyze token usage and costs	--mode costs
See subagent delegations with task/status/cost/paths	--mode subagents

Controlling Output Size

For large sessions, use --offset and --limit to page through user turns:

# Skip first 3 user turns, show next 5
uv run scripts/read_session.py <path> --mode conversation --offset 3 --limit 5

Control content truncation with --max-content:

# Show full tool outputs (no truncation)
uv run scripts/read_session.py <path> --mode full --max-content 0

# Shorter previews (500 chars per block)
uv run scripts/read_session.py <path> --mode full --max-content 500

Step 3b: Drill into Subagent Sessions

When a session contains subagent calls, the --mode subagents output shows paths to each subagent's own JSONL session. Read those with the same script:

# Persistent artifact copy (always available)
uv run scripts/read_session.py ~/.pi/agent/sessions/<project>/subagent-artifacts/<hash>_worker.jsonl --mode overview

# Temp session file (may be cleaned up)
uv run scripts/read_session.py $TMPDIR/pi-subagent-session-<id>/run-0/<timestamp>.jsonl --mode overview

Subagent sessions use the exact same JSONL format. The overview and full modes all handle subagent data — they show inline summaries with agent, model, cost, duration, and status for each subagent run.

Step 4: Report Findings

When summarizing a session for the user, include:

1. What was the goal — first user message intent
2. What happened — key steps taken, tools used, decisions made
3. Outcome — did it succeed? What was the final state?
4. Notable issues — errors, retries, workarounds, wasted effort
5. Cost — total spend and token usage

Session Format Reference

If you need to understand the raw JSONL format (for custom parsing), read: references/session-format.md

The critical thing to know: message content is nested at line.message.content, NOT line.content. Content is always an array of typed objects (text, toolCall, thinking). Tool results are separate message entries with role: "toolResult".