feat(framework): P3 — extract Constitution (L0) + gut AGENTS dispatcher (#575)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

packages/mosaic/framework/runtime/codex/RUNTIME.md

@@ -8,7 +8,7 @@ This file applies only to Codex runtime behavior.
 
 1. Follow global load order in `~/.config/mosaic/AGENTS.md`.
 2. Use `~/.codex/instructions.md` and `~/.codex/config.toml` as runtime config sources.
-3. Treat sequential-thinking MCP as required.
+3. Structured reasoning (Constitution) binds to the sequential-thinking MCP on this harness; it is REQUIRED — if unavailable, report the failure and stop planning-intensive execution.
 4. If runtime config conflicts with global rules, global rules win.
 5. Documentation rules are inherited from `~/.config/mosaic/AGENTS.md` and `~/.config/mosaic/guides/DOCUMENTATION.md`.
 6. For issue/PR/milestone actions, run Mosaic git wrappers first (`~/.config/mosaic/tools/git/*.sh`) and do not call raw `gh`/`tea`/`glab` first.