# Output Length Guard Plugin
> Author: Mihai Criveti
> Version: 0.1.0
Guards tool outputs by enforcing minimum/maximum character lengths. Supports truncate or block strategies.
## Hooks
- tool_post_invoke
## Config
```yaml
config:
min_chars: 0 # 0 disables minimum check
max_chars: 15000 # null disables maximum check
strategy: "truncate" # truncate | block
ellipsis: "…" # used when truncating
```
## Example
```yaml
- name: "OutputLengthGuardPlugin"
kind: "plugins.output_length_guard.output_length_guard.OutputLengthGuardPlugin"
hooks: ["tool_post_invoke"]
mode: "permissive"
priority: 160
config:
max_chars: 8192
strategy: "truncate"
```
## Design
- Hook placement: runs at `tool_post_invoke` to evaluate and possibly transform final text.
- Supported shapes: `str`, `{text: str}`, `list[str]`; conservative no-op for other types.
- Strategies:
- truncate: trims only over-length content and appends `ellipsis`.
- block: returns a violation when result length is outside `[min_chars, max_chars]`.
- Metadata: includes original/new length, strategy, min/max for auditability.
## Limitations
- Non-text payloads are ignored; nested shapes beyond `result.text` are not traversed.
- `truncate` strategy does not expand under-length outputs, only annotates.
- Counting is Unicode codepoints (not grapheme clusters); may differ from UI-perceived length.
## TODOs
- Add support for token-based budgets using model-specific tokenizers.
- Add opt-in traversal for nested structures and arrays of dicts.
- Optional word-boundary truncation to avoid mid-word cuts.
