feat(pi): add persistent Mosaic goal controller

docs/guides/user-guide.md

@@ -8,9 +8,10 @@
 4. [Tasks](#tasks)
 5. [Settings](#settings)
 6. [CLI Usage](#cli-usage)
-7. [Sub-package Commands](#sub-package-commands)
-8. [Telemetry](#telemetry)
-9. [Local Fleet Canary](./fleet-local-canary.md)
+7. [Pi Persistent Goals](#pi-persistent-goals)
+8. [Sub-package Commands](#sub-package-commands)
+9. [Telemetry](#telemetry)
+10. [Local Fleet Canary](./fleet-local-canary.md)
 
 ---
 
@@ -307,6 +308,57 @@ mosaic prdy
 mosaic quality-rails
 ```
 
+## Pi Persistent Goals
+
+`mosaic pi` loads a Mosaic-owned goal extension from
+`~/.config/mosaic/runtime/pi/goal-extension.ts`. It is deliberately not installed in
+`~/.pi/agent/extensions/`; framework installation and updates manage it with the rest of the Mosaic
+runtime assets.
+
+Start Pi, then set a goal:
+
+```text
+/goal set Deliver the feature, tests, documentation, and verification evidence
+# Shorthand:
+/goal Deliver the feature, tests, documentation, and verification evidence
+```
+
+Control and inspect the loop with:
+
+| Command                | Behavior                                                           |
+| ---------------------- | ------------------------------------------------------------------ |
+| `/goal status`         | Show phase, limits, compaction checks, latest report, and evidence |
+| `/goal pause [reason]` | Stop autonomous continuation while preserving the goal             |
+| `/goal resume`         | Resume with fresh turn and no-progress counters                    |
+| `/goal cancel`         | Cancel the goal and remove its active status                       |
+| `/goal help`           | Show command help                                                  |
+
+While a goal is active, Mosaic injects its contract before every Pi model request and checks every
+completed model/tool turn. The agent ends each work cycle with the structured
+`mosaic_goal_report` tool. `achieved` is provisional until a second consecutive report rechecks the
+whole goal with evidence. A continuation report or a successful compaction resets provisional
+verification.
+
+Goal statements and reports are stored in Pi session data. Mosaic redacts common credential shapes
+before appending its goal-state entries and before goal tool output or `/goal status`, but
+pattern-based redaction is not a secret store. Pi's own model-message and tool-call records are
+outside that redactor. Never put tokens, passwords, private keys, connection strings, or raw
+sensitive output in a goal or report; cite the command, artifact, and pass/fail result instead.
+
+The loop stops instead of running forever when it is paused, blocked, cancelled, verified, reaches
+its turn limit, or repeats the same no-progress report too many times. Defaults are 40 turns and 6
+repeated no-progress reports. Operators may lower or raise them within enforced bounds before
+launching Pi:
+
+```bash
+MOSAIC_GOAL_MAX_TURNS=60 MOSAIC_GOAL_MAX_NO_PROGRESS=8 mosaic pi
+```
+
+Goal state is branch-specific Pi session data. It survives compaction and session resume, but Pi's
+process still must be relaunched or supervised after a process/host failure. This initial verifier
+checks structured evidence twice; it cannot mathematically prove every arbitrary natural-language
+goal. Use explicit acceptance criteria and inspect `/goal status` for consequential work.
+
 ---
 
 ### Claude Code Skill Registration