docs: add per package README for implementation details (AI generated with human review)

agent/pkg/agentproxy/README.md

@@ -0,0 +1,122 @@
+# agent/pkg/agentproxy
+
+Package for configuring HTTP proxy connections through the GoDoxy Agent using HTTP headers.
+
+## Overview
+
+This package provides types and functions for parsing and setting agent proxy configuration via HTTP headers. It supports both a modern base64-encoded JSON format and a legacy header-based format for backward compatibility.
+
+## Architecture
+
+```mermaid
+graph LR
+    A[HTTP Request] --> B[ConfigFromHeaders]
+    B --> C{Modern Format?}
+    C -->|Yes| D[Parse X-Proxy-Config Base64 JSON]
+    C -->|No| E[Parse Legacy Headers]
+    D --> F[Config]
+    E --> F
+
+    F --> G[SetAgentProxyConfigHeaders]
+    G --> H[Modern Headers]
+    G --> I[Legacy Headers]
+```
+
+## Public Types
+
+### Config
+
+```go
+type Config struct {
+    Scheme string       // Proxy scheme (http or https)
+    Host   string       // Proxy host (hostname or hostname:port)
+    HTTPConfig         // Extended HTTP configuration
+}
+```
+
+The `HTTPConfig` embedded type (from `internal/route/types`) includes:
+
+- `NoTLSVerify` - Skip TLS certificate verification
+- `ResponseHeaderTimeout` - Timeout for response headers
+- `DisableCompression` - Disable gzip compression
+
+## Public Functions
+
+### ConfigFromHeaders
+
+```go
+func ConfigFromHeaders(h http.Header) (Config, error)
+```
+
+Parses proxy configuration from HTTP request headers. Tries modern format first, falls back to legacy format if not present.
+
+### proxyConfigFromHeaders
+
+```go
+func proxyConfigFromHeaders(h http.Header) (Config, error)
+```
+
+Parses the modern base64-encoded JSON format from `X-Proxy-Config` header.
+
+### proxyConfigFromHeadersLegacy
+
+```go
+func proxyConfigFromHeadersLegacy(h http.Header) Config
+```
+
+Parses the legacy header format:
+
+- `X-Proxy-Host` - Proxy host
+- `X-Proxy-Https` - Whether to use HTTPS
+- `X-Proxy-Skip-Tls-Verify` - Skip TLS verification
+- `X-Proxy-Response-Header-Timeout` - Response timeout in seconds
+
+### SetAgentProxyConfigHeaders
+
+```go
+func (cfg *Config) SetAgentProxyConfigHeaders(h http.Header)
+```
+
+Sets headers for modern format with base64-encoded JSON config.
+
+### SetAgentProxyConfigHeadersLegacy
+
+```go
+func (cfg *Config) SetAgentProxyConfigHeadersLegacy(h http.Header)
+```
+
+Sets headers for legacy format with individual header fields.
+
+## Header Constants
+
+Modern headers:
+
+- `HeaderXProxyScheme` - Proxy scheme
+- `HeaderXProxyHost` - Proxy host
+- `HeaderXProxyConfig` - Base64-encoded JSON config
+
+Legacy headers (deprecated):
+
+- `HeaderXProxyHTTPS`
+- `HeaderXProxySkipTLSVerify`
+- `HeaderXProxyResponseHeaderTimeout`
+
+## Usage Example
+
+```go
+// Reading configuration from incoming request headers
+func handleRequest(w http.ResponseWriter, r *http.Request) {
+    cfg, err := agentproxy.ConfigFromHeaders(r.Header)
+    if err != nil {
+        http.Error(w, "Invalid proxy config", http.StatusBadRequest)
+        return
+    }
+
+    // Use cfg.Scheme and cfg.Host to proxy the request
+    // ...
+}
+```
+
+## Integration
+
+This package is used by `agent/pkg/handler/proxy_http.go` to configure reverse proxy connections based on request headers.