claude-jsonl-compressor

claude-jsonl-compressor is a skill for Codex from brandrylabs/claude-jsonl-compressor. It costs 52 tokens per session (2,884 once invoked), scanned A, original, GPL-3.0.

A tool for making Claude Code session files smaller by compressing JSONL records, a text format that stores one JSON object per line.

In plain words
What is it for?
Use it to compact one .claude/projects session file, keep it usable for page-based reading, and support rewinding to recent context.
Why use it?
It reduces session size while preserving the active conversation branch, recent raw context, and a backup of the live file.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Good fit Use it to compact one .claude/projects session file, keep it usable for page-based reading, and support rewinding to recent context.

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Install with agentmods
npx agentmods add skills/brandrylabs/claude-jsonl-compressor/claude-jsonl-compressor
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add brandrylabs/claude-jsonl-compressor --skill claude-jsonl-compressor
Clone the repo
git clone --depth 1 https://github.com/brandrylabs/claude-jsonl-compressor

Made for: Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for claude-jsonl-compressor

README.md
[![agentmods](https://agentmods.dev/badge/skills/brandrylabs/claude-jsonl-compressor/claude-jsonl-compressor/github.svg)](https://agentmods.dev/skills/brandrylabs/claude-jsonl-compressor/claude-jsonl-compressor)
Your own site
<a href="https://agentmods.dev/skills/brandrylabs/claude-jsonl-compressor/claude-jsonl-compressor"><img src="https://agentmods.dev/badge/skills/brandrylabs/claude-jsonl-compressor/claude-jsonl-compressor/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for claude-jsonl-compressor

Your own site · 80×15
<a href="https://agentmods.dev/skills/brandrylabs/claude-jsonl-compressor/claude-jsonl-compressor"><img src="https://agentmods.dev/badge/skills/brandrylabs/claude-jsonl-compressor/claude-jsonl-compressor.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,884 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00052 $0.02884
Opus 5.5 $0.00021 $0.01154
Sonnet 5.5 $0.00010 $0.00577
Haiku 4.5 $0.00005 $0.00288

Measured 1mo ago against content hash f56dba4dccc2, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

claude-jsonl-compressor scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

The scan reads SKILL.md. This mod also ships 3 executable files (scripts/claude_session_tools.py, scripts/compress_claude_jsonl.py, scripts/repair_claude_jsonl.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

SKILL.md · 231 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago Changed · -115 lines · -39 tokens per session f56dba4dccc2
  2. 1mo ago First seen · 346 lines · 91 tokens per session scan A d4d552e745fb

Subscribe to this mod's changes

claude-jsonl-compressor is a skill published in the GitHub repository brandrylabs/claude-jsonl-compressor (2 stars, last pushed 1mo ago), licensed GPL-3.0. It adds 52 tokens to every session and 2,884 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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