session — metadata (version, id, timestamp, cwd)
message — user or assistant messages with content and tool calls
model_change — provider/model switches
thinking_level_change — thinking level adjustments
custom_message — hook output/errors, VCS notifications
compaction — context summary when session was truncated

Loading & Filtering

# Load a single session
open-jsonl ~/.pi/agent/sessions/<project>/<session>.jsonl

# Load all sessions from a project
ls ~/.pi/agent/sessions/<project>/*.jsonl
| each { |f| open-jsonl $f.name } | flatten

Finding Tool Calls

Extract all tool calls from assistant messages:

# All tool calls with names and arguments
open-jsonl session.jsonl
| where type == "message" | where message.role == "assistant"
| get message.content | flatten
| where type == "toolCall" | select id name arguments

# Bash commands specifically
open-jsonl session.jsonl
| where type == "message" | where message.role == "assistant"
| get message.content | flatten
| where type == "toolCall" | where name == "bash"
| get arguments.command

# Files read
open-jsonl session.jsonl
| where type == "message" | where message.role == "assistant"
| get message.content | flatten
| where type == "toolCall" | where name == "read"
| get arguments.path

# Thinking content
open-jsonl session.jsonl
| where type == "message" | where message.role == "assistant"
| get message.content | flatten
| where type == "thinking" | get thinking

Hook Errors & VCS Notifications

# All hook errors (eslint, typecheck failures)
open-jsonl session.jsonl | where type == "custom_message" | where customType == "hook-error"
| select timestamp content

# VCS notifications (jj squashes)
open-jsonl session.jsonl | where type == "custom_message"
| where customType | str starts-with "Squashed"
| select customType content timestamp

Session Statistics

# Count events by type
open-jsonl session.jsonl | get type | uniq --count

# Count tool calls by type
open-jsonl session.jsonl
| where type == "message" | where message.role == "assistant"
| get message.content | flatten | where type == "toolCall"
| get name | uniq --count

# Token usage
open-jsonl session.jsonl
| where type == "message" | where message.role == "assistant"
| get message.usage | flatten | math sum

Custom Helper Functions

def "session-stats" [file: path] {
    let data = (open-jsonl $file)
    {
        total_events: ($data | length),
        messages: ($data | where type == "message" | length),
        tool_calls: ($data | where type == "message" | where message.role == "assistant" | get message.content | flatten | where type == "toolCall" | length),
        hook_errors: ($data | where type == "custom_message" | where customType == "hook-error" | length)
    }
}

Constraints

Session paths contain encoded directory paths with -- prefix/suffix
Tool calls are embedded in assistant messages under message.content[] with type == "toolCall"
Use flatten to extract nested arrays from message.content
Timestamps are ISO 8601 strings or Unix milliseconds

pi-session-logs

pi-session-logs

Define the Helper Function

Entry Types