2026-03-25: Branch Convergence and Plugin Porting Guide

What Changed

• synced IMPROVEMENTS.md from origin/frain/improve
• restored MIND_FILE_SPEC.md from origin/frain/improve
• added a branch convergence plan for codex and frain
• added a plugin porting guide for adapting route-based plugins into the codex runtime model
• linked the new guidance into builder docs and roadmap docs

Why It Matters

MindStore currently has two strong branches with different strengths:

• codex: runtime, docs, tests, MCP, scheduling, extension foundation
• frain: plugin breadth, UI breadth, feature polish

This release documents how those two lines should converge without destroying either one.

Convergence Decision

• codex is the destination branch
• frain feature logic and UI should be ported into codex in slices
• first example ports should be kindle-importer, flashcard-maker, and voice-to-memory