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https://github.com/fardjad/context-dropper

A CLI for iterating through a fixed list of files, tracking position, and tagging progress.
https://github.com/fardjad/context-dropper

ai-agents cli llm-context opencode-plugin

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A CLI for iterating through a fixed list of files, tracking position, and tagging progress.

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README 

          
# context-dropper



`context-dropper` is a CLI for iterating through a fixed list of files, tracking

position, and tagging progress.



## Why Context Dropper?



AI coding agents struggle with large codebases in two main ways:



1. **Search doesn't guarantee coverage:** Agents often rely on semantic or

   keyword search to find relevant files, and it works well in many cases. But

   for tasks that require iterating over every file in a set, there is no

   guarantee that search alone will find them all.

2. **Context windows are a hard constraint:** Feeding an entire codebase into an

   LLM at once is often simply impossible. Codebases frequently exceed the

   model's token limit. Even when it fits, reasoning quality degrades as the

   context grows.



`context-dropper` solves this by enforcing strict, programmable processing

loops.



Instead of relying on search, a precise list of target files (a "fileset") is

curated upfront - either manually or by using other tools - and the agent is

instructed to process that exact list sequentially. As the agent moves from one

file to the next, it can drop the previous file's tokens from memory. Each file

is then evaluated in a **clean context**.



This approach guarantees 100% file coverage, minimizes token usage, and keeps

the model's reasoning sharp.



### A Conceptual Example



Consider an agent tasked with exploring a large codebase to document every piece

of authentication logic it finds into a single file

(`authentication-discovery.md`). Without `context-dropper`, the agent would use

search to find files containing keywords like "auth", "login", or "session", and

might miss files that contain authentication logic but don't match those

keywords. With `context-dropper`, the agent instead iterates over a fixed,

curated list of files, such as all files in a subdirectory or a filtered list

from a test coverage report.



Here is how that looks in practice:



1. **The Fileset**: A discrete list of target files is provided to the tool:

   - `src/auth/login.ts`

   - `src/routes/api.ts`

   - `src/middleware/session.ts`

2. **The Dropper**: A "dropper" is created and attached to that fileset. The

   dropper acts as a stateful bookmark that tracks exactly where the agent is in

   the list (it can go forward or backward).

3. **The Loop**: The AI agent is given a strict set of instructions: _"Read the

   current file from the dropper. If authentication logic is found, append the

   findings to `authentication-discovery.md`. Then mark the file as 'processed',

   and move the dropper to the next file until the list is exhausted."_



By explicitly unloading the previous file from its context window before moving

the dropper, the context size remains small. This prevents the LLM from blowing

past its token limits or suffering from degraded reasoning. In theory, an

unlimited number of files can be processed this way.



## Installation



You can install `context-dropper` using one of the following methods.



### 1. Download Pre-compiled Binary (Recommended)



Download the latest standalone executable for your operating system from the

[Releases](https://github.com/fardjad/context-dropper/releases) page. Ensure it

is executable and in your `PATH`.



```bash

chmod +x context-dropper

mv context-dropper /usr/local/bin/

```



### 2. Install via Package Manager



You can install the package globally from NPM.



**Bun:**



```bash

bun install -g context-dropper

```



**NPM:**



```bash

npm install -g context-dropper

```



Then run it anywhere:



```bash

context-dropper --help

```



### 3. Build from Source (Development)



To develop, compile binaries from source, or contribute to the project, please

refer to the [Contributing Guide](CONTRIBUTING.md).



## Command Shape



```bash

context-dropper [--data-dir ] 

```



Global option:



- `--data-dir `: directory where filesets and droppers are stored.

- Default: `./.context-dropper` resolved from current working directory.



If run with no command, usage/help is shown. If `fileset` or `dropper` are run

without a subcommand, that group help is shown.



## Data Layout



The CLI stores state under `data-dir`:



```text

data-dir/

  filesets/

    .txt

  droppers/

    .json

```



Fileset file (`filesets/.txt`):



- One normalized absolute file path per line.

- Import is immutable: importing the same fileset name again fails.



Dropper file (`droppers/.json`):



```json

{

  "fileset": "my-fileset",

  "pointer_position": 0,

  "tags": {

    "processed": ["/abs/path/a.ts", "/abs/path/b.ts"]

  }

}

```



- `tags` is `tag -> filename[]`.

- Filename arrays are deduplicated and sorted.



## Name Rules



Fileset/dropper names must:



- Match `^[A-Za-z0-9._-]+$`

- Not be `.` or `..`

- Not contain path separators



## Commands



### `fileset`



Import from a list file:



```bash

context-dropper fileset import --name  

```



- `listFilePath` must be plain text with one path per line.

- Blank lines are ignored.

- Relative lines are resolved from the list file directory.

- Each referenced file must exist and be readable.

- Stored entries become normalized absolute paths.



List filesets:



```bash

context-dropper fileset list

```



- Output: one fileset name per line.



Show fileset contents:



```bash

context-dropper fileset show 

```



- Output: one file path per line.



Remove fileset:



```bash

context-dropper fileset remove 

```



- Fails if any dropper still references it.



### `dropper`



Create:



```bash

context-dropper dropper create --fileset  

```



Show current file contents:



```bash

context-dropper dropper show 

```



Move pointer forward:



```bash

context-dropper dropper next 

```



- Silent on success.



Move pointer backward:



```bash

context-dropper dropper previous 

```



- Silent on success.



Tag current item:



```bash

context-dropper dropper tag  --tag  [--tag ]...

```



List tags of current item:



```bash

context-dropper dropper list-tags 

```



- Output: one tag per line.



Remove tags from current item:



```bash

context-dropper dropper remove-tag  --tag  [--tag ]...

```



List dropper entries with optional filters:



```bash

context-dropper dropper list-files  [--tag ]... [--filename ]

```



- Output: paths only, one per line.

- Repeated `--tag` uses OR semantics.

- `--filename` is exact path match.

- When both are provided: AND semantics (`filename` match and tag OR match).

- Aliases: `context-dropper dropper ls-files `



List all droppers, optionally filtered by fileset name:



```bash

context-dropper dropper list [--fileset ]

```



- Output: one dropper name per line.

- When `--fileset` is provided, filters for droppers referencing that fileset.

- Aliases: `context-dropper dropper ls [--fileset ]`



Dump dropper materialized state:



```bash

context-dropper dropper dump 

```



- Output: pretty JSON.



Remove dropper:



```bash

context-dropper dropper remove 

```



Check completion:



```bash

context-dropper dropper is-done 

```



- Done condition: every file has at least one tag.

- If done: prints `true` and exits `0`.

- If not done: exits non-zero with an error listing untagged files.



## OpenCode Plugin



This repository also includes a dedicated, self-contained plugin for

[OpenCode](https://github.com/opencode-ai/opencode) under `opencode-plugin/`.

The plugin natively binds to the `context-dropper` APIs and lets you iterate

through filesets autonomously inside an OpenCode chat session. See

[opencode-plugin/README.md](./opencode-plugin/README.md) for installation and

usage instructions.



## Exit Codes



- `0`: success

- `1`: application error

- `2`: usage/argument error

- `3`: dropper exhausted (`show` with no current item, or `next` at end)

- `4`: dropper at start (`previous` at start)



## Suggested AI-Agent Workflow



1. Import a fileset:

   `context-dropper fileset import --name  `

2. Create a dropper:

   `context-dropper dropper create --fileset  `

3. Ask the agent to perform the task (for example: review/document each file)

   and follow the processing loop below.



## Agent Loop Rule



When acting as an agent over a dropper, use this exact loop:



1. Run `context-dropper dropper show `.

2. Perform the requested task on that file content.

3. Run `context-dropper dropper tag  --tag processed`.

4. Run `context-dropper dropper is-done `.

5. If `is-done` succeeded and printed `true`, stop.

6. If `is-done` failed because untagged items remain, run

   `context-dropper dropper next ` and repeat from step 1.



Notes for agents:



- `next` and `previous` are movement only; they do not print file contents.

- Use `show` to read the current file.

- Do not stop on `is-done` non-zero unless the message is not

  `Untagged items remain: ...`.