session-source-recovery

name	session-source-recovery
description	Recover lost source files from pi session history when files were deleted but never committed to git.
triggers	["file was deleted","file is missing","recover from session","session history"]

Session Source Recovery

Problem

An agent deleted or lost source files that were never committed to git. The files may still exist in pi session JSONL files as tool call arguments (e.g., apply_patch calls).

Recovery Steps

1. Locate Sessions

Search pi session history for references to the lost files:

grep -rl "filename-or-package-name" ~/.pi/agent/sessions/ --include="*.jsonl"

2. Extract Patches

Pi sessions store apply_patch tool calls as JSON with patchText fields containing *** Begin Patch / *** End Patch blocks.

3. Parse and Reconstruct

Use Python to extract file contents from JSONL:

import json, re
# Read JSONL, find toolCall blocks with name="apply_patch"
# Extract patchText, split on *** Add/Modify File: directives
# Strip leading + and line numbers from patch content

4. Verify

• Check TypeScript types match imports
• Run tsc --noEmit if possible
• Cross-reference with other sessions for the most recent version

Session JSONL Structure

• Root type: session (metadata)
• Messages: type message with message.role and message.content (list of blocks)
• Tool calls: blocks with type: "toolCall", name: "apply_patch", arguments.patchText
• Tool results: separate message entries with matching tool call IDs

Caveats

• Only works if the session JSONL files haven't been purged
• Files created via write tool (not apply_patch) may have different structure
• Binary files cannot be recovered from text JSONL
• Multiple sessions may have different versions — prefer the most recent