feat: add Devin platform support and MCP server integration

[isaiahfrantz]

Summary

Adds support for running Understand Anything on Devin, plus a new stdio MCP server (@understand-anything/mcp) that exposes knowledge-graph tools to any MCP-capable agent. Devin is supported through its Claude-plugin compatibility layer — the same plugin.json, skills, hooks, and agents work unmodified, with small portability fixes where Devin's runtime differs from Claude Code's.

Changes

New packages/mcp — MCP server

• bin/understand-anything-mcp.mjs: stdio MCP server exposing six tools over an existing .ua/ (or legacy .understand-anything/) graph:
  • understand_status — graph presence, metadata, counts, freshness
  • understand_search — fuzzy search + 1-hop graph context
  • understand_explain — deep-dive on a file or file:function
  • understand_diff — impact analysis of current git changes
  • understand_onboard — full onboarding guide
  • understand_dashboard — launch the dashboard, return the URL
• Depends on @understand-anything/core and @understand-anything/skill via workspace deps; includes a standalone README with client config examples (.devin/config.json shown for Devin).

Hooks portability

• hooks/hooks.json: PostToolUse matcher broadened to ^(Bash|exec)$ so it fires on Devin's exec tool as well as Claude's Bash.
• New hooks/session-start-stale-check.mjs: replaces the inline shell one-liner in the SessionStart hook. Emits hookSpecificOutput.additionalContext JSON — the only form Devin injects into context — and resolves the update prompt relative to its own location, so no platform-specific env var is needed.
• post-tool-use-auto-update.mjs: falls back to resolving auto-update-prompt.md from the script's own location when CLAUDE_PLUGIN_ROOT is unset.
• auto-update-prompt.md: plugin-root resolution now tries $DEVIN_PLUGIN_ROOT and the parent of the hooks/ dir containing the prompt.

Skills

• understand, understand-domain, understand-dashboard SKILL.md plugin-root resolution blocks gain two candidates: $DEVIN_PLUGIN_ROOT and <SKILL_DIR>/../.. (Devin's agent shell has no plugin-root variable; the skill's own base directory is the reliable anchor).

Installers

• install.sh / install.ps1: new devin platform target (~/.agents/skills, per-skill style), with a post-install tip pointing at devin plugins install for the full plugin experience.

Docs

• README: Devin section covering the two install paths (plugin via devin plugins install Egonex-AI/Understand-Anything#understand-anything-plugin, or skills-only via install.sh devin), MCP server registration snippet, badge, and compatibility table row.
• CLAUDE.md: new "Devin Integration" section documenting how Devin loads the plugin and the invariants to preserve (no .devin-plugin/plugin.json — a native manifest would take precedence over the Claude one); versioning list updated to seven files for the new package.

Design notes

• No native Devin manifest. Devin's Claude-plugin compatibility reads .claude-plugin/plugin.json and hooks/hooks.json, sets CLAUDE_PLUGIN_ROOT for hook commands, and loads agents/ as understand-anything:<name> subagents. A .devin-plugin/plugin.json would take precedence and break this.
• MCP instead of more skills. Read/query operations are exposed via the MCP server rather than duplicated as skills, per each platform's strengths.

Testing

• New tests/hooks/session-start-stale-check.test.mjs (109 lines) covering the stale-check hook; post-tool-use-auto-update.test.mjs updated for the prompt-path fallback.

Versioning note

packages/mcp/package.json carries a "version" field — the release checklist now spans seven files.