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Context Builder

Generate LLM-optimized codebase context from any directory using context-builder CLI.

Rating: 4.7 (404 reviews)
Downloads: 1,217 downloads
Version: 1.0.0

Overview

Generate LLM-optimized codebase context from any directory using context-builder CLI.

Complete Documentation

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Context Builder — Agentic Skill

Generate a single, structured markdown file from any codebase directory. The output is optimized for LLM consumption with relevance-based file ordering, AST-aware code signatures, automatic token budgeting, and smart defaults.

Installation

bash

# Requires Rust toolchain. Builds from source with cryptographic verification via crates.io.
cargo install context-builder --features tree-sitter-all

Pre-built binaries with SHA256 checksums are also available for manual download from GitHub Releases.

Verify: context-builder --version (expected: 0.8.3)

Security & Path Scoping

IMPORTANT: This tool reads file contents from the specified directory. Agents MUST follow these rules:

Only target explicit project directories — always pass the exact project root (e.g., /home/user/projects/myapp). Never point at home directories, system paths, or credential stores (~/.ssh, ~/.aws, /etc, ~, /)
Use scoped filters — use -f to limit to known source extensions (e.g., -f rs,toml,md), reducing exposure surface
Output to project-local paths — write output to the project's docs/ folder or /tmp/, never to shared or public locations
Review before sharing — the output may contain API keys, secrets, or credentials embedded in source files; always review or use .gitignore patterns to exclude sensitive files

Built-in protections (always active, no configuration needed):

Excludes .git/, node_modules/, and 19 other heavy/sensitive directories at any depth
Respects .gitignore rules when a .git directory is present
Binary files are auto-detected and skipped via UTF-8 sniffing
Output file and cache directory are auto-excluded to prevent self-ingestion

When to Use

Deep code review — Feed an entire codebase to an LLM for architecture analysis or bug hunting
Onboarding — Generate a project snapshot for understanding unfamiliar codebases
Diff-based updates — After code changes, generate only the diffs to update an LLM's understanding
AST signatures — Extract function/class signatures for token-efficient structural understanding
Cross-project research — Quickly package a dependency's source for analysis

Core Workflow

1. Quick Context (whole project)

bash

context-builder -d /path/to/project -y -o context.md

-y skips confirmation prompts (recommended for agent workflows when path is explicitly scoped)
Output includes: header → file tree → files sorted by relevance (config → source → tests → docs)

2. Scoped Context (specific file types)

bash

context-builder -d /path/to/project -f rs,toml -i docs,assets -y -o context.md

-f rs,toml includes only Rust and TOML files
-i docs,assets excludes directories by name

3. AST Signatures Mode (minimal tokens)

bash

context-builder -d /path/to/project --signatures -f rs,ts,py -y -o signatures.md

Replaces full file content with extracted function/class signatures (~4K vs ~15K tokens per file)
Supports 8 languages: Rust, JavaScript (.js/.jsx), TypeScript (.ts/.tsx), Python, Go, Java, C, C++
Requires --features tree-sitter-all at install time

4. Signatures with Structural Summary

bash

context-builder -d /path/to/project --signatures --structure -y -o context.md

--structure appends a count summary (e.g., "6 functions, 2 structs, 1 impl block")
Combine with --visibility public to show only public API surface

5. Budget-Constrained Context

bash

context-builder -d /path/to/project --max-tokens 100000 -y -o context.md

Caps output to ~100K tokens (estimated)
Files are included in relevance order until budget is exhausted
Automatically warns if output exceeds 128K tokens

6. Token Count Preview

bash

context-builder -d /path/to/project --token-count

Prints estimated token count without generating output
Use this first to decide if filtering or --signatures is needed

7. Incremental Diffs

First, ensure context-builder.toml exists with:

toml

timestamped_output = true
auto_diff = true

Then run twice:

bash

# First run: baseline snapshot
context-builder -d /path/to/project -y

# After code changes: generates diff annotations
context-builder -d /path/to/project -y

For minimal output (diffs only, no full file bodies):

bash

context-builder -d /path/to/project -y --diff-only

Smart Defaults

These behaviors require no configuration:

Feature	Behavior
Auto-ignore	node_modules, dist, build, __pycache__, .venv, vendor, and 12 more heavy dirs are excluded at any depth
Self-exclusion	Output file, cache dir, and context-builder.toml are auto-excluded
.gitignore	Respected automatically when .git directory exists
Binary detection	Binary files are skipped via UTF-8 sniffing
File ordering	Config/docs first → source (entry points before helpers) → tests → build/CI → lockfiles

CLI Reference (Agent-Relevant Flags)

Flag	Purpose	Agent Guidance
-d	Input directory	Always use absolute paths for reliability
-o	Output path	Write to project docs/ or /tmp/
-f	Filter by extension	Comma-separated: -f rs,toml,md
-i	Ignore dirs/files	Comma-separated: -i tests,docs,assets
--max-tokens	Token budget cap	Use 100000 for most models, 200000 for Gemini
--token-count	Dry-run token estimate	Run first to check if filtering is needed
-y	Skip all prompts	Use only with explicit, scoped project paths
--preview	Show file tree only	Quick exploration without generating output
--diff-only	Output only diffs	Minimizes tokens for incremental updates
--signatures	AST signature extraction	Requires tree-sitter-all feature at install
--structure	Structural summary	Pair with --signatures for compact output
--visibility	Filter by visibility	all (default), public (public API only)
--truncate	Truncation strategy	smart (AST-aware) or simple
--init	Create config file	Auto-detects project file types
--clear-cache	Reset diff cache	Use if diff output seems stale

Recipes

Recipe: Deep Think Code Review

Generate a scoped context file, then prompt an LLM for deep analysis:

bash

# Step 1: Generate focused context
context-builder -d /path/to/project -f rs,toml --max-tokens 120000 -y -o docs/deep_think_context.md

# Step 2: Feed to LLM with a review prompt
# Attach docs/deep_think_context.md and ask for:
# - Architecture review
# - Bug hunting
# - Performance analysis

Recipe: API Surface Review (signatures only)

bash

# Extract only public signatures — typically 80-90% fewer tokens than full source
context-builder -d /path/to/project --signatures --visibility public -f rs -y -o docs/api_surface.md

Recipe: Compare Two Versions

bash

# Generate context for both versions
context-builder -d ./v1 -f py -y -o /tmp/v1_context.md
context-builder -d ./v2 -f py -y -o /tmp/v2_context.md

# Feed both to an LLM for comparative analysis

Recipe: Monorepo Slice

bash

# Focus on a specific package within a monorepo
context-builder -d /path/to/monorepo/packages/core -f ts,tsx -i __tests__,__mocks__ -y -o core_context.md

Recipe: Quick Size Check Before Deciding Strategy

bash

# Check if the project fits in context
context-builder -d /path/to/project --token-count

# If > 128K tokens, try signatures mode first:
context-builder -d /path/to/project --signatures --token-count

# Or scope it down:
context-builder -d /path/to/project -f rs,toml --max-tokens 100000 --token-count

Configuration File (Optional)

Create context-builder.toml in the project root for persistent settings:

toml

output = "docs/context.md"
output_folder = "docs"
filter = ["rs", "toml"]
ignore = ["target", "benches"]
timestamped_output = true
auto_diff = true
max_tokens = 120000
signatures = true
structure = true
visibility = "public"

Initialize one automatically with context-builder --init.

Output Format

The generated markdown follows this structure:

# Directory Structure Report [metadata: project name, filters, content hash]

## File Tree [visual tree of included files]

## Files ### File: src/main.rs [code block with file contents, syntax-highlighted by extension]

### File: src/lib.rs ...

Files appear in relevance order (not alphabetical), prioritizing config and entry points so LLMs build understanding faster.

When --signatures is active, file contents are replaced with extracted signatures:

### File: src/lib.rs

rust

pub fn run_with_args(args: Args, config: Config, prompter: &dyn Prompter) -> Result<()>
    pub fn generate_markdown_with_diff(...) -> Result<String>

Error Handling

If context-builder is not installed, install with cargo install context-builder --features tree-sitter-all
If --signatures shows no output for a file, the language may not be supported or the feature was not enabled at install
If output exceeds token limits, add --max-tokens or narrow with -f / -i, or use --signatures
If the project has no .git directory, auto-ignores still protect against dependency flooding
Use --clear-cache if diff output seems stale or incorrect

Installation

Terminal bash


openclaw install context-builder

Copied!

💻Code Examples

cargo install context-builder --features tree-sitter-all

cargo-install-context-builder---features-tree-sitter-all.txt

Pre-built binaries with SHA256 checksums are also available for manual download from [GitHub Releases](https://github.com/igorls/context-builder/releases/latest).

Verify: `context-builder --version` (expected: `0.8.3`)


## Security & Path Scoping

> **IMPORTANT**: This tool reads file contents from the specified directory. Agents MUST follow these rules:

- **Only target explicit project directories** — always pass the exact project root (e.g., `/home/user/projects/myapp`). Never point at home directories, system paths, or credential stores (`~/.ssh`, `~/.aws`, `/etc`, `~`, `/`)
- **Use scoped filters** — use `-f` to limit to known source extensions (e.g., `-f rs,toml,md`), reducing exposure surface
- **Output to project-local paths** — write output to the project's `docs/` folder or `/tmp/`, never to shared or public locations
- **Review before sharing** — the output may contain API keys, secrets, or credentials embedded in source files; always review or use `.gitignore` patterns to exclude sensitive files

**Built-in protections** (always active, no configuration needed):
- Excludes `.git/`, `node_modules/`, and 19 other heavy/sensitive directories at any depth
- Respects `.gitignore` rules when a `.git` directory is present
- Binary files are auto-detected and skipped via UTF-8 sniffing
- Output file and cache directory are auto-excluded to prevent self-ingestion

## When to Use

- **Deep code review** — Feed an entire codebase to an LLM for architecture analysis or bug hunting
- **Onboarding** — Generate a project snapshot for understanding unfamiliar codebases
- **Diff-based updates** — After code changes, generate only the diffs to update an LLM's understanding
- **AST signatures** — Extract function/class signatures for token-efficient structural understanding
- **Cross-project research** — Quickly package a dependency's source for analysis

## Core Workflow

### 1. Quick Context (whole project)

context-builder -d /path/to/project -y -o context.md

context-builder--d-pathtoproject--y--o-contextmd.txt

- `-y` skips confirmation prompts (recommended for agent workflows when path is explicitly scoped)
- Output includes: header → file tree → files sorted by relevance (config → source → tests → docs)

### 2. Scoped Context (specific file types)

context-builder -d /path/to/project -f rs,toml -i docs,assets -y -o context.md

context-builder--d-pathtoproject--f-rstoml--i-docsassets--y--o-contextmd.txt

- `-f rs,toml` includes only Rust and TOML files
- `-i docs,assets` excludes directories by name

### 3. AST Signatures Mode (minimal tokens)

context-builder -d /path/to/project --signatures -f rs,ts,py -y -o signatures.md

context-builder--d-pathtoproject---signatures--f-rstspy--y--o-signaturesmd.txt

- Replaces full file content with extracted function/class signatures (~4K vs ~15K tokens per file)
- Supports 8 languages: Rust, JavaScript (.js/.jsx), TypeScript (.ts/.tsx), Python, Go, Java, C, C++
- Requires `--features tree-sitter-all` at install time

### 4. Signatures with Structural Summary

context-builder -d /path/to/project --signatures --structure -y -o context.md

context-builder--d-pathtoproject---signatures---structure--y--o-contextmd.txt

- `--structure` appends a count summary (e.g., "6 functions, 2 structs, 1 impl block")
- Combine with `--visibility public` to show only public API surface

### 5. Budget-Constrained Context

context-builder -d /path/to/project --max-tokens 100000 -y -o context.md

context-builder--d-pathtoproject---max-tokens-100000--y--o-contextmd.txt

- Caps output to ~100K tokens (estimated)
- Files are included in relevance order until budget is exhausted
- Automatically warns if output exceeds 128K tokens

### 6. Token Count Preview

context-builder -d /path/to/project --token-count

context-builder--d-pathtoproject---token-count.txt

- Prints estimated token count without generating output
- Use this first to decide if filtering or `--signatures` is needed

### 7. Incremental Diffs

First, ensure `context-builder.toml` exists with:

context-builder -d /path/to/project -y --diff-only

context-builder--d-pathtoproject--y---diff-only.txt

## Smart Defaults

These behaviors require no configuration:

| Feature | Behavior |
|---------|----------|
| **Auto-ignore** | `node_modules`, `dist`, `build`, `__pycache__`, `.venv`, `vendor`, and 12 more heavy dirs are excluded at any depth |
| **Self-exclusion** | Output file, cache dir, and `context-builder.toml` are auto-excluded |
| **.gitignore** | Respected automatically when `.git` directory exists |
| **Binary detection** | Binary files are skipped via UTF-8 sniffing |
| **File ordering** | Config/docs first → source (entry points before helpers) → tests → build/CI → lockfiles |

## CLI Reference (Agent-Relevant Flags)

| Flag | Purpose | Agent Guidance |
|------|---------|----------------|
| `-d <PATH>` | Input directory | **Always use absolute paths** for reliability |
| `-o <FILE>` | Output path | Write to project `docs/` or `/tmp/` |
| `-f <EXT>` | Filter by extension | Comma-separated: `-f rs,toml,md` |
| `-i <NAME>` | Ignore dirs/files | Comma-separated: `-i tests,docs,assets` |
| `--max-tokens <N>` | Token budget cap | Use `100000` for most models, `200000` for Gemini |
| `--token-count` | Dry-run token estimate | Run first to check if filtering is needed |
| `-y` | Skip all prompts | **Use only with explicit, scoped project paths** |
| `--preview` | Show file tree only | Quick exploration without generating output |
| `--diff-only` | Output only diffs | Minimizes tokens for incremental updates |
| `--signatures` | AST signature extraction | Requires `tree-sitter-all` feature at install |
| `--structure` | Structural summary | Pair with `--signatures` for compact output |
| `--visibility <V>` | Filter by visibility | `all` (default), `public` (public API only) |
| `--truncate <MODE>` | Truncation strategy | `smart` (AST-aware) or `simple` |
| `--init` | Create config file | Auto-detects project file types |
| `--clear-cache` | Reset diff cache | Use if diff output seems stale |

## Recipes

### Recipe: Deep Think Code Review

Generate a scoped context file, then prompt an LLM for deep analysis:

context-builder -d /path/to/project -f rs,toml --max-tokens 100000 --token-count

context-builder--d-pathtoproject--f-rstoml---max-tokens-100000---token-count.txt

## Configuration File (Optional)

Create `context-builder.toml` in the project root for persistent settings:

visibility = "public"

visibility--public.txt

Initialize one automatically with `context-builder --init`.

## Output Format

The generated markdown follows this structure:

    # Directory Structure Report
    [metadata: project name, filters, content hash]

    ## File Tree
    [visual tree of included files]

    ## Files
    ### File: src/main.rs
    [code block with file contents, syntax-highlighted by extension]

    ### File: src/lib.rs
    ...

Files appear in **relevance order** (not alphabetical), prioritizing config and entry points so LLMs build understanding faster.

When `--signatures` is active, file contents are replaced with extracted signatures:

    ### File: src/lib.rs