docs: add CHANGELOG.md and a docs-update policy

AGENTS.md

@@ -109,3 +109,10 @@ environment-qualified runs for Python-version or docs-specific work.
 - CLI test outputs, compiled workflow artifacts, downloaded files and generated
   docs are products of tests or commands. Do not check them in unless they are
   intentional fixtures.
+
+## Documentation and Changelog
+
+User-facing changes — new features, behavior changes, bug fixes, breaking changes — must add an
+entry to `CHANGELOG.md` under `## [Unreleased]`, in the matching [Keep a
+Changelog](https://keepachangelog.com/en/1.1.0/) category (Added, Changed, Deprecated, Removed,
+Fixed, Security). This repository has no `docs/` yet.

CHANGELOG.md

@@ -0,0 +1,27 @@
+# Changelog
+
+All notable changes to this project are documented in this file.
+
+The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/). This project uses
+calendar versioning (`YYYY.MM.N`) rather than semantic versioning.
+
+Add new entries under `## [Unreleased]`, in the category they belong to. At release time, rename
+`## [Unreleased]` to `## [<version>] - <YYYY-MM-DD>` and start a fresh `## [Unreleased]` above it.
+
+## [Unreleased]
+
+### Added
+
+- Progress display for distributed execution updates.
+
+### Changed
+
+- Now depends on `fasthep-toolbench[display,http]` explicitly, since Toolbench is making `rich`,
+  `httpx` and `tabulate` optional extras rather than hard dependencies.
+
+## [2026.08.2] - 2026-08-25
+
+### Added
+
+- Partition selection for runtime commands.
+- Simple progress reporting during command execution.