arachna 2.5.0

Context collector for AI — gathers project files into token-limited chunks

arachna

Context collector for AI — gathers project files into token-limited chunks.

arachna is built with arachna — 970 tests, 93% coverage, 180+ commits.

What I believe

I'm a solo developer building tools for myself. arachna is an indie project — not a startup, not a company, not a product for sale. Free software. AGPLv3.

I believe AI tools should be independent. Not tied to a specific editor, cloud provider, or way of working. arachna doesn't lock you in. It prepares your project for AI to understand. The rest is up to you.

• Any editor. Vim, VS Code, Cursor, Emacs — arachna doesn't care where you write code
• Any LLM. Local models, cloud APIs, web chats — the brain is your choice
• Plain files. No databases, no daemons, no hidden state. Everything is transparent — you can cat, grep, diff the output
• No telemetry. No tracking, no cloud sync, no phoning home. Your code stays on your machine
• Zero dependencies. Just Python 3.11+ stdlib. pip install arachna, that's it
• Free software, not just open source. AGPLv3 guarantees the four freedoms. No proprietary forks. What's the difference?

Contents

• What arachna does
• Install
• Quick start
• Examples
• Commands
• Options
• Profiles
• Split modes
• All config fields
• Output
• Manifest and cleanup
• Incremental mode
• Watch — snapshots and diffs
• Safety
• Doctor
• Git hooks (optional)
• Tokenizer
• Supported project types
• Links
• License

What arachna does

arachna collects your project files into files ready to be sent to an AI. It understands tokens (not lines) and splits output smartly so nothing gets cut in the middle.

Install

pip install arachna

Quick start

cd your-project
arachna --init
arachna --all

Creates arachna_context/ with .md files ready for AI.

Examples

Local model (Ollama)

arachna --profile code
cat arachna_context/chat-code_1.md | ollama run qwen2.5:32b

Cloud API (OpenAI)

arachna --profile code
# Then paste arachna_context/chat-code_1.md into chat.openai.com
# Or use the API:
curl https://api.openai.com/v1/chat/completions \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -d '{"messages": [{"role": "user", "content": "'"$(cat arachna_context/chat-code_1.md)"'"}]}'

Multiple profiles for different tasks

# Give code to the Programmer agent
arachna --profile code

# Give tests to the Tester agent
arachna --profile tests

# Give docs to the Auditor agent
arachna --profile docs

# Give git history for context
arachna --profile git

Incremental mode (only changed files)

arachna --profile code --incremental
# First run: collects everything
# Second run: skips unchanged files, creates nothing

Agent workflow with snapshots (10-50x token savings)

arachna --snapshot create --profile code --name "baseline"
# ... AI makes changes to your project ...
arachna --diff --from baseline
# Sends only the diff, not the full project

Full project as diff (no snapshot needed)

arachna --diff --all --profile code
arachna --diff --all --profile code --mode repo-map

Dry-run (preview without writing)

arachna --all --dry-run

Safety check

arachna --validate
# Checks config for errors, exits 1 if problems found

Commands

arachna --init              interactive setup
arachna --init --defaults   auto-detect everything
arachna --init --preset X   use specific preset
arachna --all               collect all profiles
arachna --profile code      collect one profile
arachna --all --dry-run     preview without writing
arachna --clean             remove collected files
arachna --list              show profiles
arachna --validate          check config for errors
arachna --doctor            run full diagnostic
arachna --install-hook      install post-commit git hook (optional)
arachna --presets-update    update presets from remote repository

Watch commands

arachna --snapshot                          show usage hint
arachna --snapshot list                     list all snapshots
arachna --snapshot create --profile X --name Y   create snapshot
arachna --snapshot update <id>              update snapshot
arachna --snapshot delete <id>              delete snapshot
arachna --snapshot info <id>                show snapshot details
arachna --snapshot rename <old> <new>       rename snapshot
arachna --diff                              diff from single snapshot (auto)
arachna --diff --from <id>                  diff from specific snapshot
arachna --diff --from A --to B              cross-snapshot diff
arachna --diff --all --profile X            full project as diff (no snapshot)
arachna --diff --stat                       stats only (no content)
arachna --diff --flat                       flat output (no grouping)
arachna --diff --format xml                 XML output
arachna --diff --mode structural            structural (block-level) diff
arachna --store stats                       store statistics
arachna --store gc                          garbage collect

Collection modes

arachna --all                               full content (default)
arachna --all --mode headers                with dependency/export headers
arachna --all --mode repo-map               signatures only (50-70% less tokens)
arachna --all --query "authentication"      filter files by query

Options

Option	Description
--output-dir path	where to write (default: arachna_context/)
--verbose	show skipped files
--compress	remove blank lines and trailing spaces
--incremental	only files changed since last run
--format xml,json	markdown (default), xml, or json
--merge	append to existing output instead of replacing
--dry-run	preview without writing files
--force	force overwrite with --install-hook
--query "text"	filter files by query
--mode full,headers,repo-map	collection mode

Profiles

Profiles let you separate context by role — different context for different AI tasks.

Example .arachna.json for a Python project:

{
  "project_name": "MyProject",
  "profiles": {
    "code": {
      "split_mode": "by_file",
      "directories": ["src", "app"],
      "patterns": ["*.py"],
      "files": ["pyproject.toml", "requirements.txt"],
      "pre_commands": ["tree src app"],
      "max_tokens": 16000
    },
    "tests": {
      "split_mode": "by_file",
      "directories": ["tests"],
      "patterns": ["*.py"],
      "max_tokens": 16000
    },
    "docs": {
      "split_mode": "by_file",
      "files": ["README.md", "TODO.md", "CHANGELOG.md"],
      "max_tokens": 16000
    },
    "git": {
      "split_mode": "by_marker",
      "split_marker": "\n=== COMMIT:",
      "command": "git log --reverse --format='=== COMMIT: %h ===%nTITLE: %s%n%nMESSAGE:%n%b%n'",
      "max_tokens": 16000
    }
  }
}

Split modes

• by_file: code and docs, each file stays intact (default)
• by_paragraph: logs, splits on blank lines
• by_marker: git history, splits on custom marker
• single: everything in one file, truncates if too big

All config fields

• split_mode: by_file, by_paragraph, by_marker, or single
• split_marker: string for by_marker mode
• directories: folders to scan
• patterns: glob patterns like ["*.py"]
• files: specific files to include
• exclude_patterns: glob patterns to skip
• pre_commands: shell commands before collection
• post_commands: shell commands after collection
• command: use command output instead of files
• max_tokens: token limit per output file
• section_format: markdown, xml, or json
• compress: safe whitespace compression (blank lines, trailing spaces). Does not modify indentation
• include_binary: include binaries as base64 (true/false)
• binary_extensions: whitelist like [".png"]
• binary_max_mb: max binary file size in MB

Output

Files go to arachna_context/ (configurable):

arachna_context/
  .arachna_manifest.json
  chat-manifest.md          # summary of all files
  chat-code_1.md
  chat-tests_1.md
  chat-docs_1.md
  chat-git_1.md
  chat-diff-cycle_1.md      # diff output (includes snapshot name)

When content exceeds max_tokens, files are numbered: chat-code_1.md, chat-code_2.md...

Manifest and cleanup

Every created file is tracked in .arachna_manifest.json. Running --all again removes old files automatically. With --profile, only that profile's files are cleaned.

Incremental mode

With --incremental, arachna skips files unchanged since last run. Uses .arachna_cache.json with mtime_ns + size + SHA256 hashes (smart hybrid — fast path without hashing, SHA256 fallback for false positives like git checkout).

Watch — snapshots and diffs

Watch is a subsystem for incremental AI workflows. Instead of sending full project context (50k+ tokens) every time, create a snapshot once, then send only changes (diff) in subsequent iterations.

How it works

# Create a baseline snapshot
arachna --snapshot create --profile code --name "before-refactor"

# AI or developer makes changes to the project
# ...

# See what changed (grouped by type)
arachna --diff --from before-refactor
# Output:
#   ## Changes from before-refactor to current (1 renamed, 2 modified)
#   ### Renamed
#   RENAMED: src/old.py → src/new.py
#   ### Modified
#   ### src/main.py
#   REMOVED/ADDED...

# Cross-snapshot diff (between two snapshots)
arachna --diff --from v1 --to v2

# Full project as diff (no snapshot needed)
arachna --diff --all --profile code
arachna --diff --all --profile code --mode repo-map

# Just the stats
arachna --diff --from before-refactor --stat
# Modified: 3, Added: 1, Renamed: 1, Deleted: 0

# Flat output (old format, backward compatible)
arachna --diff --from before-refactor --flat

# Structural diff (understands code blocks)
arachna --diff --from before-refactor --mode structural

Rename and move detection

arachna automatically detects renamed and moved files:

# Exact rename (same content hash)
RENAMED: src/old.py → src/new.py

# Exact move (same content, different directory)
MOVED: src/utils.py → lib/utils.py

# Similar rename (content > 70% similar)
RENAMED: src/old.py → src/new.py (87% similar)

No git needed — works on any project.

Headers, query, and repo-map

arachna can add context headers showing dependencies and exports for each file. Use --mode headers or --query to auto-enable headers.

# Collect with dependency/export headers
arachna --all --mode headers

# Filter by query (keyword scoring + import chain)
arachna --all --query "authentication"

# Repo-map mode — signatures only, no bodies
arachna --all --mode repo-map
# 50-70% token savings for project overview

Content-addressable store

Snapshots are stored in .arachna/store/ (never committed — auto-gitignored). Files are deduplicated by SHA256 hash. Multiple snapshots share identical content — only one copy stored.

arachna --store stats
# Store statistics:
#   Snapshots: 5
#   Objects: 127
#   Total size: 2.3 MB
#   Unique content: 1.1 MB (52% deduplication)

arachna --store gc
# Removed 15 objects (freed 2.3 MB)

Snapshot management

# List all snapshots
arachna --snapshot list

# Show snapshot details
arachna --snapshot info before-refactor

# Show profile only
arachna --snapshot info before-refactor --profile

# Update a snapshot (re-scan current state)
arachna --snapshot update before-refactor

# Rename a snapshot
arachna --snapshot rename before-refactor after-refactor

# Delete a snapshot (objects survive for other snapshots)
arachna --snapshot delete before-refactor

Programmatic API (v2.0.0+)

All Watch and collection features are available as a Python API:

from arachna import watch
from arachna.collect_api import collect

# Create snapshot
sid = watch.create_snapshot(profile="full", name="baseline")

# Collect context
result = collect(profile="full", mode="repo-map")

# Compute diff
diff = watch.compute_diff(snapshot_id="baseline", mode="structural")
print(f"Modified: {diff.stats.modified}, Added: {diff.stats.added}")

See TUTORIAL.md for full API documentation and LLM_INTEGRATION.md for LLM agent workflow.

Diff format

Human-readable diff optimized for AI consumption:

### src/main.py

REMOVED lines 45-47:
    total = 0
    for item in items:
        total += item.price

ADDED lines 45:
    return sum(item.price for item in items)

Safety

Commands in .arachna.json (pre_commands, post_commands, command) are validated before execution. Unknown or dangerous commands are blocked. The command allowlist is strictly read-only — no interpreters, no filesystem modification. Use --dry-run to preview what will be executed.

Doctor

arachna --doctor runs a full diagnostic — validates all profiles, checks that directories and files exist, verifies .gitignore integration.

Git hooks (optional)

If you prefer git-based workflow, arachna can integrate via post-commit hooks. But it works fine without git.

arachna --install-hook

Configure the command in .arachna.json:

{
  "hook": {
    "post-commit": "arachna --all --incremental"
  }
}

Tokenizer

arachna uses a conservative estimate: 4 characters = 1 token. Works for any model with a 20-30% safety margin.

Built-in (default)

No dependencies. Always works. Set max_tokens below your model's context window:

• 8192 window → max_tokens: 6000
• 32768 window → max_tokens: 24000

Custom tokenizer

Add to your .arachna.json:

  "tokenizer": "my_module:count_tokens"

Your module must export count_tokens(text) -> int:

# my_tok.py
def count_tokens(text: str) -> int:
    return max(1, len(text) // 4)  # your logic here

Cloud models

For exact token counts, install tiktoken:

pip install tiktoken

  "tokenizer": "tiktoken:cl100k_base"    # GPT-4, DeepSeek
  "tokenizer": "tiktoken:o200k_base"     # GPT-4o

Local models

For HuggingFace tokenizers, install transformers:

pip install transformers

  "tokenizer": "transformers:Qwen/Qwen2.5-7B-Instruct"
  "tokenizer": "transformers:mistralai/Mistral-7B-Instruct-v0.3"
  "tokenizer": "transformers:google/gemma-7b"

Note: transformers is a heavy dependency. For most local models, the built-in estimate with safety margin is sufficient.

Supported project types

arachna --init auto-detects 24 project types:

Languages

• Python: src/, app/, lib/, pkg/, scripts/, *.py, pyproject.toml
• JavaScript/TypeScript: src/, app/, lib/, *.js, *.ts, package.json
• C/C++: src/, include/, *.c, *.cpp, *.h, CMakeLists.txt
• C#: *.cs, *.csproj, *.sln
• Swift: Sources/, *.swift, Package.swift
• Kotlin/Java: src/, *.kt, *.java, build.gradle, pom.xml
• Ruby: lib/, app/, *.rb, Gemfile
• PHP: src/, app/, public/, *.php, composer.json
• Go: *.go, go.mod, go.sum, main.go
• Rust: src/, *.rs, Cargo.toml, Cargo.lock
• Zig: src/, *.zig, build.zig, build.zig.zon
• Lua: src/, lib/, *.lua, *.rockspec
• Elixir: lib/, *.ex, *.exs, mix.exs
• Haskell: src/, app/, *.hs, *.lhs, *.cabal, stack.yaml
• Gleam: src/, *.gleam, gleam.toml, manifest.toml

Engines

• Godot: *.gd, *.tscn, *.tres, project.godot
• Unity: Assets/, *.cs, *.unity, *.prefab
• Unreal Engine: Source/, Content/, *.cpp, *.h, *.cs, *.uproject, *.uplugin

Infrastructure

• Docker: Dockerfile, docker-compose.yml
• Terraform: *.tf, *.tfvars

Service

• tests: tests/, test/
• docs: docs/, README.md, TODO.md, CHANGELOG.md, Makefile
• config: pyproject.toml, package.json, go.mod, Cargo.toml, requirements.txt
• git: git log --reverse with commit history

Custom presets

Create presets.json in your project root to add or override presets:

{
  "my_game": {
    "dirs": ["game"],
    "patterns": ["*.lua"],
    "max_tokens": 8000,
    "split_mode": "by_file",
    "detect": ["game"]
  }
}

Use with: arachna --init --preset my_game

Presets update

Fetch updated presets from the remote repository:

arachna --presets-update
# Merges with built-in presets, local presets.json never overwritten

arachna --presets-update --url https://example.com/presets.json
# Use custom URL

Links

• GitHub Repository
• Issue Tracker
• Changelog
• Architecture
• LLM Integration

License

arachna is free software licensed under GNU AGPLv3. This license guarantees the four essential freedoms: to run the program for any purpose, to study and modify it, to redistribute copies, and to distribute modified versions.

Why AGPLv3 and not MIT or Apache? Because permissive licenses allow proprietary forks. AGPLv3 ensures that derivative works — including software running as a network service — remain free. No proprietary forks. No closed modifications. What the community builds, the community keeps.

See LICENSE for the full legal text.