[MarkoSchuetz]

Adds the Index entry for backlog_md, a plugin that drives the
Backlog.md CLI from the Agent Zero agent
loop.

What the plugin does

One backlog tool with action routing over the upstream markdown task manager:
tasks with acceptance criteria, milestones, documents, search, archive/restore,
project config, and a Kanban board. Work items stay plain .md files inside the
target repository, so one task remains one reviewable unit in git.

Repository

https://github.com/MarkoSchuetz/a0-backlog-md

The root plugin.yaml uses name: backlog_md, matching this folder. The
repository also carries an MIT LICENSE and a README covering requirements,
configuration, cleanup, and licensing.

Upstream sync, not vendoring

Following the pattern of mattpocock_skills, no upstream code is committed. The
install() hook installs backlog.md from npm into a plugin-local prefix,
verifies the binary with backlog --version, and records the resolved version in
upstream.yaml. A failed fetch keeps the previously installed binary, so an
offline restart still works. The same pipeline is exposed as a re-sync API
endpoint and a WebUI button.

Verification

Tested against backlog.md 1.55.3: init on a plain directory, create with
multiple acceptance criteria, list/view/edit/search, archive/restore, overview,
milestone, document, config, and instructions. Three CLI constraints found by
testing are encoded in the tool: --json is accepted only by list/view/search,
--ac is repeatable rather than comma-separated, and config get requires a
key.

Checklist

• One plugin folder per PR, no extra files
• Folder name matches the remote root plugin.yaml name
• Required fields present; within title, description, and total length limits
• github points to a public repository with an MIT LICENSE
• No existing entry uses this name or repository URL

[a0-bot]

Plugin submission validation failed

ERROR: Only files under plugins/ are allowed in plugin PRs: TAGS.md