# EOS String Implementation Summary

This document summarizes the implementation of the custom `eos_string` parameter feature.

## Changes Made

### 1. Core Generation Module (`steadytext/core/generator.py`)

- Added `eos_string` parameter to `DeterministicGenerator.generate()` method
  - Default value: `"[EOS]"` (special marker for model's default EOS token)
  - When custom value provided, it's added to the stop sequences
  
- Added `eos_string` parameter to `DeterministicGenerator.generate_iter()` method
  - Supports streaming generation with custom stop strings
  - Added `include_logprobs` parameter for compatibility with CLI

- Updated caching logic to include `eos_string` in cache key when not default
  - Ensures different eos_strings produce separately cached results

### 2. Public API (`steadytext/__init__.py`)

- Updated `generate()` function signature:
  ```python
  def generate(prompt: str, return_logprobs: bool = False, eos_string: str = "[EOS]")
  ```

- Updated `generate_iter()` function signature:
  ```python
  def generate_iter(prompt: str, eos_string: str = "[EOS]", include_logprobs: bool = False)
  ```

### 3. CLI Updates

#### Generate Command (`steadytext/cli/commands/generate.py`)
- Added `--eos-string` parameter (default: "[EOS]")
- Passes eos_string to both batch and streaming generation

#### Main CLI (`steadytext/cli/main.py`)
- Added `--quiet` / `-q` flag to silence log output
- Sets logging level to ERROR for both steadytext and llama_cpp loggers when quiet mode is enabled

### 4. Tests (`tests/test_steadytext.py`)

Added three new test methods:
- `test_generate_with_custom_eos_string()` - Tests basic eos_string functionality
- `test_generate_iter_with_eos_string()` - Tests streaming with custom eos_string
- `test_generate_eos_string_with_logprobs()` - Tests combination of eos_string and logprobs

### 5. Test Scripts

Created two test scripts for manual verification:
- `test_eos_string.py` - Python script testing various eos_string scenarios
- `test_cli_eos.sh` - Bash script testing CLI functionality

## Usage Examples

### Python API

```python
import steadytext

# Use model's default EOS token
text = steadytext.generate("Hello world", eos_string="[EOS]")

# Stop at custom string
text = steadytext.generate("List items until END", eos_string="END")

# Streaming with custom eos
for token in steadytext.generate_iter("Generate text", eos_string="STOP"):
    print(token, end="")
```

### CLI

```bash
# Default behavior
steadytext "Generate some text"

# Custom eos string
steadytext "Generate until DONE" --eos-string "DONE"

# Quiet mode (no logs)
steadytext --quiet "Generate without logs"

# Streaming with custom eos
steadytext "Stream until END" --stream --eos-string "END"
```

## Implementation Notes

1. The `"[EOS]"` string is a special marker that tells the system to use the model's default EOS token and stop sequences.

2. When a custom eos_string is provided, it's added to the existing stop sequences rather than replacing them.

3. Cache keys include the eos_string when it's not the default, ensuring proper caching behavior.

4. The quiet flag affects all loggers in the steadytext namespace and llama_cpp if present.