feat(pi): add persistent Mosaic goal controller

README.md

@@ -60,6 +60,14 @@ The launcher verifies your config, checks for `SOUL.md`, injects your `AGENTS.md
 
 Pi launches default to a token-lean skill posture: `mosaic pi` passes `--no-skills` so Pi does not preload every global skill description into the system prompt. Use `MOSAIC_PI_SKILL_MODE=all mosaic pi` for the legacy all-skills catalog, or `MOSAIC_PI_SKILL_MODE=discover mosaic pi` to let Pi use its native settings/project skill discovery.
 
+Mosaic also loads its Pi extensions from `~/.config/mosaic/runtime/pi/`. Inside Pi,
+`/goal set <statement>` starts a bounded persistent loop that checks every turn and successful
+compaction, requires two evidence-bearing completion reports, and can be inspected or stopped with
+`/goal status`, `/goal pause`, `/goal resume`, and `/goal cancel`. Controller-owned goal-state
+entries redact common credential shapes, but Pi's model/tool-call history is separate, so goals and
+evidence must never contain secrets or raw sensitive output. Mosaic does not install this extension
+into `~/.pi/agent/extensions/`.
+
 ### TUI & Gateway
 
 ```bash