move pi-mono into companion-cloud as apps/companion-os

- Copy all pi-mono source into apps/companion-os/
- Update Dockerfile to COPY pre-built binary instead of downloading from GitHub Releases
- Update deploy-staging.yml to build pi from source (bun compile) before Docker build
- Add apps/companion-os/** to path triggers
- No more cross-repo dispatch needed

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/coding-agent/test/compaction-extensions-example.test.ts

@@ -0,0 +1,81 @@
+/**
+ * Verify the documentation example from extensions.md compiles and works.
+ */
+
+import { describe, expect, it } from "vitest";
+import type {
+  ExtensionAPI,
+  SessionBeforeCompactEvent,
+  SessionCompactEvent,
+} from "../src/core/extensions/index.js";
+
+describe("Documentation example", () => {
+  it("custom compaction example should type-check correctly", () => {
+    // This is the example from extensions.md - verify it compiles
+    const exampleExtension = (pi: ExtensionAPI) => {
+      pi.on(
+        "session_before_compact",
+        async (event: SessionBeforeCompactEvent, ctx) => {
+          // All these should be accessible on the event
+          const { preparation, branchEntries } = event;
+          // sessionManager, modelRegistry, and model come from ctx
+          const { sessionManager, modelRegistry } = ctx;
+          const {
+            messagesToSummarize,
+            turnPrefixMessages,
+            tokensBefore,
+            firstKeptEntryId,
+            isSplitTurn,
+          } = preparation;
+
+          // Verify types
+          expect(Array.isArray(messagesToSummarize)).toBe(true);
+          expect(Array.isArray(turnPrefixMessages)).toBe(true);
+          expect(typeof isSplitTurn).toBe("boolean");
+          expect(typeof tokensBefore).toBe("number");
+          expect(typeof sessionManager.getEntries).toBe("function");
+          expect(typeof modelRegistry.getApiKey).toBe("function");
+          expect(typeof firstKeptEntryId).toBe("string");
+          expect(Array.isArray(branchEntries)).toBe(true);
+
+          const summary = messagesToSummarize
+            .filter((m) => m.role === "user")
+            .map(
+              (m) =>
+                `- ${typeof m.content === "string" ? m.content.slice(0, 100) : "[complex]"}`,
+            )
+            .join("\n");
+
+          // Extensions return compaction content - SessionManager adds id/parentId
+          return {
+            compaction: {
+              summary: `User requests:\n${summary}`,
+              firstKeptEntryId,
+              tokensBefore,
+            },
+          };
+        },
+      );
+    };
+
+    // Just verify the function exists and is callable
+    expect(typeof exampleExtension).toBe("function");
+  });
+
+  it("compact event should have correct fields", () => {
+    const checkCompactEvent = (pi: ExtensionAPI) => {
+      pi.on("session_compact", async (event: SessionCompactEvent) => {
+        // These should all be accessible
+        const entry = event.compactionEntry;
+        const fromExtension = event.fromExtension;
+
+        expect(entry.type).toBe("compaction");
+        expect(typeof entry.summary).toBe("string");
+        expect(typeof entry.tokensBefore).toBe("number");
+        expect(typeof fromExtension).toBe("boolean");
+      });
+    };
+
+    expect(typeof checkCompactEvent).toBe("function");
+  });
+});