docs: add CHANGELOG covering v0.1.0 and v0.2.0 (on-demand scan endpoint)

CHANGELOG.md

@@ -1,25 +1,35 @@
 # Changelog
 
-All notable changes to this project will be documented in this file.
+Notable changes to the KrakenKey Probe. Format follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/). Versions follow [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
-and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+---
 
-## [0.1.0] - 2026-03-17
+## [Unreleased]
+
+---
+
+## [v0.2.0] — 2026-05-03
 
 ### Added
+- `POST /scan` — authenticated on-demand scan endpoint. Enabled via `KK_PROBE_SCAN_API_ENABLED=true`; protected by a Bearer token (`KK_PROBE_SCAN_API_SECRET`, minimum 32 characters enforced at startup).
+- `ScanAPIConfig` struct in the configuration (`scan_api.enabled` / `scan_api.secret` YAML keys).
+- Startup validation: fails with a clear error message if the scan API secret is shorter than 32 characters.
+- Used by KrakenKey API's `POST /public/scan` to proxy free TLS scan requests to the hosted probe.
+- `KK_PROBE_SCAN_API_ENABLED` and `KK_PROBE_SCAN_API_SECRET` env vars documented in README.
+- **On-Demand Scan API** section added to README covering config, request format, response shape, and security guidance.
+- **Troubleshooting** entry added for secret-length startup error.
+
+---
 
-- TLS endpoint scanner with certificate metadata extraction (subject, SANs, issuer, chain, expiry, fingerprint, key type, signature algorithm)
-- Connection metadata collection (TLS version, cipher suite, handshake latency, OCSP stapling)
-- Three operating modes: `standalone`, `connected`, and `hosted`
-- KrakenKey API integration for probe registration and result reporting
-- Health check server with `/healthz` and `/readyz` endpoints
-- Configurable scan interval (1m to 24h) with immediate first scan on startup
-- YAML config file with environment variable overrides (`KK_PROBE_*` prefix)
-- Persistent probe ID across restarts via state file
-- Graceful shutdown on SIGINT/SIGTERM
-- Multi-platform Docker images (linux/amd64, linux/arm64) via GoReleaser
-- CI pipeline with lint, test, and build matrix
-- Kubernetes deployment example with ConfigMap, Secrets, and health probes
-
-[0.1.0]: https://github.com/krakenkey/probe/releases/tag/v0.1.0
+## [v0.1.0] — 2026-03-27
+
+### Added
+- Initial release: TLS endpoint scanning with certificate chain validation, expiry checking, and connection health metrics (TLS version, cipher suite, OCSP stapling, latency).
+- Three operating modes: `standalone` (local YAML config, no API), `connected` (user API key, reports to platform), `hosted` (service key, receives config from API by region).
+- Dynamic endpoint reloading in `connected` and `hosted` modes — polls API every 60 seconds; triggers immediate scan if endpoint list changes.
+- `/healthz` and `/readyz` HTTP health endpoints.
+- `--healthcheck` CLI flag for Docker-native health checks (`probe --healthcheck`).
+- Persistent JSON state file for probe ID and scan history.
+- Multi-architecture Docker image (`ghcr.io/krakenkey/probe`) for amd64 and arm64.
+- `CHANGELOG.md`, `CONTRIBUTING.md`, and `SECURITY.md` documentation files.
+- Pre-built goreleaser release pipeline with SHA-256 checksums.