PACT
PACT is a semantic compression format that beats ZIP by 40% on codebases and replaces Claude Code's /compact with an 18.4x lossless compaction engine.
Core trick
Compresses project files into one brotli solid stream and extracts structure without API calls for context compaction.
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Description
PACT is a semantic compression format that beats ZIP by 40% on codebases and replaces Claude Code's /compact with an
18.4x lossless compaction engine.
Three things in one tool:
1. File compression — brotli solid archive that concatenates all files into one compression stream. Cross-file pattern
deduplication that ZIP physically cannot do. 40% smaller on a 79-file real project. Semantic inspection shows every
function, import, and class without decompressing.
2. Claude Code compaction plugin — one command (pact install --global) hooks into every session. Heuristic structural
extraction at 50% context, zero API calls. 18.4x compression vs /compact's 4.0x, with 92% information retention vs
68%. The AI keeps structured state instead of lossy prose summaries.
3. Native OS integration — right-click any file on macOS, Windows, or Linux to pack/unpack. Native Swift progress UI
on macOS. One command setup: npx pact-cc setup.
BARUTU SNAKE: PACT compressed the Claude Code session that built PACT. 179 turns, 1.6M tokens → 46K tokens, 34.3x
lossless. Reproducible: node benchmarks/run.mjs --tasks 012-barutu-snake.
150 tests passing. Built in 5 days. pact.zip
README excerpt
# PACT **Semantic compression that beats ZIP by 40% on codebases.** [**pact.zip**](https://pact.zip) · [Demo video](./PACT_demo.mp4) · [Explainer](./pact-explainer.mp4) https://github.com/hmatrades/PACT/raw/main/PACT_demo.mp4 --- ```bash npx pact-cc setup # one command. right-click + Claude Code compaction. done. ``` ## Quick start ```bash pact pack myproject/ # 88 KB → 21 KB (4.2x) pact inspect myproject.pact # see functions, imports, types — no decompression pact unpack myproject.pact # restores myproject (1)/ ``` ## Install ```bash npx pact-cc setup ``` One command. Detects your OS. Installs everything: - **macOS** — Finder Quick Actions (right-click → Pack with PACT) + native Swift progress UI - **Windows** — right-click context menu via registry - **Linux** — Nautilus, Dolphin, Nemo, Thunar scripts - **All platforms** — Claude Code auto-compaction at 50% context ## Why not ZIP? ZIP compresses each file in isolation using 1993-era deflate. PACT: - **Solid brotli archive** — all files compressed as one stream. Cross-file patterns compound the ratio. - **Semantic inspection** — see functions, classes, imports without decompressing. - **40% smaller** than ZIP on real codebases. ``` ZIP: 362 KB PACT: 221 KB — 40% smaller (79 files, measured) ``` ## Claude Code compaction ```bash pact install --global # auto-compresses every session at 50% context ``` | | PACT | /compact | |---|---:|---:| | Compression | **18.4x** | 4.0x | | Retention