fix(core): make V2 reads media-aware and binary-safe (#31038)

packages/core/test/session-compaction.test.ts

@@ -0,0 +1,18 @@
+import { expect, test } from "bun:test"
+import { SessionCompaction } from "@opencode-ai/core/session/compaction"
+
+test("compaction describes tool media without embedding base64", () => {
+  const base64 = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAAB"
+  const serialized = SessionCompaction.serializeToolContent([
+    { type: "text", text: "Image read successfully" },
+    {
+      type: "file",
+      source: { type: "data", data: base64 },
+      mime: "image/png",
+      name: "pixel.png",
+    },
+  ])
+
+  expect(serialized).toBe("Image read successfully\n[Attached image/png: pixel.png]")
+  expect(serialized).not.toContain(base64)
+})