FastCtx

https://github.com/yc-duan/fastctx
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FastCtx is a local Rust tool runtime that provides fast, context-efficient repository tools for AI...
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### Install and run FastCtx

Source: https://github.com/yc-duan/fastctx/blob/main/packages/fastctx/README.md

Global installation and execution of the FastCtx CLI tool.

```console
npm install --global fastctx
fastctx
```

--------------------------------

### Install FastCtx via Cargo

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Build and install the binary directly from the Rust package registry.

```console
cargo install fastctx --locked
```

--------------------------------

### run_background

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Starts a background Bash job and returns a job id immediately.

```APIDOC
## run_background

### Description
Starts a background Bash job and returns a job id immediately. It is useful for builds, tests, development servers, and other long-running commands.
```

--------------------------------

### Execute codex-fastctx via npx

Source: https://github.com/yc-duan/fastctx/blob/main/packages/codex-fastctx/README.md

Run the compatibility shim directly using npx without a permanent installation.

```console
npx codex-fastctx
```

--------------------------------

### Run FastCtx without global installation

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Execute the control terminal as a one-off process using npx.

```console
npx fastctx
```

--------------------------------

### Run development workflow commands

Source: https://github.com/yc-duan/fastctx/blob/main/CONTRIBUTING.md

Execute these commands to format, lint, and test the project during development.

```console
cargo fmt
cargo clippy --all-targets
cargo test
```

--------------------------------

### run

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Executes a Bash command in the foreground and returns the merged stdout, stderr, and exit code.

```APIDOC
## run

### Description
Executes a Bash command in the foreground and returns merged stdout, stderr, and the exit code. It uses Git Bash on Windows and the system Bash on macOS and Linux.

### Parameters
- **command** (string) - Required - The Bash command to execute.
- **timeout_ms** (integer) - Optional - Timeout in milliseconds for the command execution.
```

--------------------------------

### Read binary file as hex

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Set the view parameter to hex to read binary files.

```json
{
  "file_path": "V:/repo/data/cache.bin",
  "view": "hex"
}
```

--------------------------------

### Execute a foreground Bash command

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Use this JSON structure to define a command and timeout for foreground execution.

```json
{
  "command": "cargo test --quiet 2>&1 | tail -n 40",
  "timeout_ms": 180000
}
```

--------------------------------

### Configure FastCtx Approval Mode

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Set the default_tools_approval_mode in the MCP server configuration to restrict tool execution.

```toml
[mcp_servers.fastctx]
default_tools_approval_mode = "writes"
```

--------------------------------

### Read file content with paging

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Use the read tool to retrieve specific lines from a file by specifying the file path, offset, and limit.

```json
{
  "file_path": "V:/repo/src/main.rs",
  "offset": 120,
  "limit": 40
}
```

--------------------------------

### Register FastCtx as an MCP server

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Manual configuration for registering the FastCtx MCP server in the Codex configuration file.

```toml
[mcp_servers.fastctx]
command = "C:/absolute/path/to/fastctx.exe"
args = ["serve"]
startup_timeout_sec = 120

[features.code_mode]
direct_only_tool_namespaces = ["mcp__fastctx"]
```

--------------------------------

### Perform batch file replacement

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Execute mechanical batch replacements across files, using dry_run to preview changes before applying them.

```json
{
  "pattern": "old_name\\(",
  "replacement": "new_name(",
  "path": "V:/repo/src",
  "glob": "**/*.rs",
  "dry_run": true
}
```

--------------------------------

### Search files with grep

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Perform regex searches across a directory using the grep tool with configurable output modes and context.

```json
{
  "pattern": "fn \\w+_lock",
  "path": "V:/repo/src",
  "output_mode": "content",
  "context": 1
}
```

--------------------------------

### read

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Reads text, images, PDFs, and raw bytes from a file. Supports paging, encoding selection, and hex views for binary files.

```APIDOC
## read

### Description
Reads content from a file. Supports text, images, PDFs, and binary data.

### Parameters
- **file_path** (string) - Required - Path to the file.
- **offset** (integer) - Optional - Starting line or byte offset.
- **limit** (integer) - Optional - Number of lines or bytes to return.
- **encoding** (string) - Optional - Explicit character encoding (e.g., gbk).
- **view** (string) - Optional - View mode, e.g., 'hex' for binary files.
```

--------------------------------

### Enable Bash tools in FastCtx

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Adds the shell enablement flag to the FastCtx server arguments.

```toml
args = ["serve", "--enable-shell"]
```

--------------------------------

### Find files with glob

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Locate files matching a specific pattern within a repository root, with options to sort by modification time.

```json
{
  "pattern": "**/*.toml",
  "path": "V:/repo",
  "sort": "modified"
}
```

--------------------------------

### job_output

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Reads new output from a background job and reports its status.

```APIDOC
## job_output

### Description
Reads new output from a background job, including jobs started in earlier sessions, and reports 'running', 'exited', or 'interrupted'.

### Parameters
- **wait_ms** (integer) - Optional - Enables long polling.
- **after_seq** (integer) - Optional - Re-anchors the read position for stable paging.
```

--------------------------------

### grep

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Searches file contents using the Rust regex engine. Supports various output modes and filtering options.

```APIDOC
## grep

### Description
Searches for patterns within files or a repository tree.

### Parameters
- **pattern** (string) - Required - Regex pattern to search.
- **path** (string) - Required - Target directory or file path.
- **output_mode** (string) - Optional - 'files_with_matches', 'content', 'count', or 'summary'.
- **context** (integer) - Optional - Number of lines of context to include.
- **head_limit** (integer) - Optional - Limit for paging results.
- **offset** (integer) - Optional - Offset for paging results.
```

--------------------------------

### Execute non-interactive CLI commands

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Perform configuration and management tasks without opening the full-screen terminal.

```console
fastctx apply --tier standard --yes
fastctx status
fastctx jobs
fastctx jobs kill j-a1b2c3
fastctx unapply --yes
```

--------------------------------

### Configure Codex code mode namespace

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Sets the FastCtx namespace as a direct top-level namespace for Codex code mode.

```toml
[features.code_mode]
direct_only_tool_namespaces = ["mcp__fastctx"]
```

--------------------------------

### glob

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Finds files based on path patterns relative to a search root.

```APIDOC
## glob

### Description
Finds files matching a specific pattern.

### Parameters
- **pattern** (string) - Required - Glob pattern.
- **path** (string) - Required - Search root directory.
- **sort** (string) - Optional - 'path' or 'modified'.
- **filter_mode** (string) - Optional - 'project' or 'all'.
- **offset** (integer) - Optional - Paging offset.
- **limit** (integer) - Optional - Paging limit.
```

--------------------------------

### job_list

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Lists background jobs based on their status.

```APIDOC
## job_list

### Description
Lists background jobs. Defaults to status='running'.

### Parameters
- **status** (string) - Optional - Filter by status ('running', 'finished', 'all').
- **offset** (integer) - Optional - Continues a page.
- **limit** (integer) - Optional - Overrides the saved page size.
```

--------------------------------

### replace

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Performs mechanical batch replacements across files or a repository tree.

```APIDOC
## replace

### Description
Applies deterministic batch replacements to files.

### Parameters
- **pattern** (string) - Required - Regex pattern to match.
- **replacement** (string) - Required - Replacement text.
- **path** (string) - Required - Target directory or file.
- **glob** (string) - Optional - Glob pattern to filter files.
- **dry_run** (boolean) - Optional - If true, previews changes without writing.
- **max_replacements** (integer) - Optional - Cap the number of replacements.
```

--------------------------------

### job_kill

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Stops the selected background job and its full process tree.

```APIDOC
## job_kill

### Description
Stops the selected background job and its full process tree. If the job has already exited, the call returns the existing exit status.
```

--------------------------------

### Read file with explicit encoding

Source: https://github.com/yc-duan/fastctx/blob/main/README.md

Specify the encoding parameter when the automatic detection fails or is ambiguous.

```json
{
  "file_path": "V:/repo/docs/legacy.txt",
  "encoding": "gbk"
}
```
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