feat(pi): add persistent Mosaic goal controller

docs/guides/dev-guide.md

@@ -9,8 +9,9 @@
 5. [Adding New MCP Tools](#adding-new-mcp-tools)
 6. [Database Schema and Migrations](#database-schema-and-migrations)
 7. [Claude Code Skill Bridge](#claude-code-skill-bridge)
-8. [API Endpoint Reference](#api-endpoint-reference)
-9. [Local Fleet Canary](./fleet-local-canary.md)
+8. [Pi Persistent Goal Extension](#pi-persistent-goal-extension)
+9. [API Endpoint Reference](#api-endpoint-reference)
+10. [Local Fleet Canary](./fleet-local-canary.md)
 
 ---
 
@@ -385,6 +386,85 @@ M1 intentionally manages Claude Code only. Pi's Mosaic launcher can discover the
 canonical root directly. Codex still relies on the existing full skill-sync
 linker and needs separate parity analysis before this lifecycle API is extended.
 
+## Pi Persistent Goal Extension
+
+The source of the Mosaic-owned Pi goal controller is:
+
+```text
+packages/mosaic/framework/runtime/pi/goal-extension.ts
+```
+
+The framework manifest classifies `runtime/**` as framework-owned. Both the bash installer and the
+TypeScript file adapter therefore deploy the same reviewed source to:
+
+```text
+$MOSAIC_HOME/runtime/pi/goal-extension.ts
+# default: ~/.config/mosaic/runtime/pi/goal-extension.ts
+```
+
+Do not copy or link this extension into `~/.pi/agent/extensions/`. The launcher function
+`discoverPiExtensionArgs()` emits the core `mosaic-extension.ts` first and the optional
+`goal-extension.ts` second, preserving compatibility with an older installed framework that does
+not have the goal file yet.
+
+### Lifecycle design
+
+| Pi API                         | Goal-controller responsibility                                                    |
+| ------------------------------ | --------------------------------------------------------------------------------- |
+| `registerCommand('goal')`      | Set, inspect, pause, resume, or cancel one branch-specific goal                   |
+| `registerTool(...)`            | Record a terminating structured progress report with evidence                     |
+| `context`                      | Inject the active goal contract before every provider request                     |
+| `turn_end`                     | Record every turn, reject mixed final reports, and enforce the turn bound         |
+| `agent_settled`                | Start one deduplicated continuation only after Pi has no retry/compact/queue work |
+| `session_compact`              | Record the compact check, reset provisional verification, and defer idle work     |
+| `session_start`/`session_tree` | Rebuild state from custom entries on the active branch                            |
+| `session_shutdown`             | Invalidate deferred callbacks and clear UI state                                  |
+
+State is appended as `mosaic-goal-state` custom entries, which do not enter model context. The
+`context` hook creates a fresh hidden `mosaic-goal-context` message for each request instead of
+trusting compaction summaries. The `mosaic_goal_report` result uses `terminate: true`; when it is the
+sole final tool call, Pi avoids an unnecessary model response before the controller decides whether
+to verify, continue, or stop.
+
+Before state is appended or displayed, the controller applies bounded credential-pattern redaction
+to the goal statement, report summary/evidence/next step, and stop reason. Fingerprints are computed
+over redacted report content. Pi session entries are append-only, so a credential-bearing legacy
+entry cannot honestly be erased by the extension: restoration fails closed, emits a warning, and
+requires removal of the affected session before setting a new goal. This is defense-in-depth rather
+than a secret-storage contract, and it does not rewrite Pi's separate model-message/tool-call
+history. Goal prompts tell the agent not to submit credentials or raw sensitive output, and tests use
+canaries to prove known forms do not reach new custom entries, status text, context, or tool details
+while ordinary typed fields such as `token: string` remain intact.
+
+Completion remains evidence-gated but semantic: two consecutive `achieved` reports are required,
+and the second run is explicitly a verification pass. This avoids an extra judge-model request after
+every turn. Deterministic validator commands are intentionally not accepted as `/goal` input in this
+slice, so never describe this mechanism as proof of arbitrary natural-language completion.
+
+### Tests and local smoke workflow
+
+```bash
+pnpm --filter @mosaicstack/mosaic exec vitest run \
+  src/runtime/pi-goal-extension.spec.ts \
+  src/commands/launch.spec.ts \
+  src/config/file-adapter.test.ts
+
+bash packages/mosaic/framework/tools/quality/scripts/test-install-migration.sh
+```
+
+For an additive local smoke test without reseeding unrelated live framework files:
+
+```bash
+install -D -m 0644 \
+  packages/mosaic/framework/runtime/pi/goal-extension.ts \
+  ~/.config/mosaic/runtime/pi/goal-extension.ts
+
+pi --extension ~/.config/mosaic/runtime/pi/goal-extension.ts
+```
+
+Use `/goal help`, `/goal set ...`, and `/goal status` in that test session. A released framework
+sync installs the file, and a released Mosaic CLI loads it automatically through `mosaic pi`.
+
 ## API Endpoint Reference
 
 All endpoints are served by the gateway at `http://localhost:14242` by default.