philter

# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [Unreleased]

## [0.2.0] - 2026-03-11

### Added
- `:extra_headers` option for `proxy/2` and `ProxyPlug` — merge additional headers into the filtered outbound request, replacing existing headers with matching names ([`044e8fc`](https://github.com/OpenFn/philter/commit/044e8fc))
- `:strip_headers` option for `proxy/2` and `ProxyPlug` — remove named headers (case-insensitive) before forwarding ([`044e8fc`](https://github.com/OpenFn/philter/commit/044e8fc))
- Mutual exclusion validation: `:headers` cannot be combined with `:extra_headers` or `:strip_headers` (raises `ArgumentError`) ([`044e8fc`](https://github.com/OpenFn/philter/commit/044e8fc))
- Configurable logging via `:log_level` option — lifecycle events logged at the configured level, or suppressed with `false` ([`daa8657`](https://github.com/OpenFn/philter/commit/daa8657))

### Fixed
- Preserve explicit `host` header in caller-supplied `:headers` instead of always rewriting it ([`d2ac7b1`](https://github.com/OpenFn/philter/commit/d2ac7b1))
- Rewrite `host` header to match upstream URL in the default (filtered) path ([`475da4c`](https://github.com/OpenFn/philter/commit/475da4c))

## [0.1.0] - 2025-02-04

### Added
- Initial release (extracted from Spike)
- `Philter.proxy/2` for controller-based proxying
- `Philter.ProxyPlug` for router-level forwarding
- `Philter.Handler` behaviour for lifecycle callbacks
  - `handle_request_started/2` - Called before sending to upstream
  - `handle_response_started/2` - Called on first byte received (TTFB)
  - `handle_response_finished/2` - Called with complete observations
- Body observation with O(1) memory:
  - SHA256 hash computed incrementally
  - Byte size tracking
  - UTF-8 safe preview (first 64KB)
  - Timing information (TTFB, duration)
- Conditional body accumulation based on content-type and size
- Configurable timeouts, payload limits, content-type filtering
- Full test coverage with Bypass for upstream mocking