fix(mcp): retain complete application results across response limits

Retain complete authenticated application Evidence when the repeated MCP representation exceeds the default receive frame or Node string limit. Return a typed transport constraint, keep useful followup queries available, and stream full canonical bundles to atomic destinations.

Verify complete Notion and Obsidian workflows on Linux and native Windows, full CLI/Evidence parity, and real large Chrome screenshot recovery. Preserve complete success contracts and caller-selected evidence paths.

Refs #1065, #1053.

src/server/toolResultEncoding.test.ts

@@ -0,0 +1,55 @@
+import { describe, expect, it } from "vitest";
+
+import type { JsonValue } from "../domain/jsonValue.js";
+import { encodeToolResult } from "./toolResultEncoding.js";
+
+const projectedResult = (candidate: JsonValue) => ({
+  content: [{ type: "text", text: JSON.stringify(candidate) }],
+  structuredContent: candidate,
+});
+
+describe("MCP result encoding budget", () => {
+  it.each([
+    { result: { value: 1 } },
+    { result: ["中文", "😀", "\ud800", '"\\\n'] },
+    { result: "x".repeat(8191) + "😀" + '中文\n"'.repeat(20000) },
+  ])("counts actual UTF-8 structured and escaped text bytes", (candidate) => {
+    const encoded = encodeToolResult(candidate);
+    expect(encoded.ok).toBe(true);
+    if (!encoded.ok) throw new Error("Expected complete encoding");
+    expect(encoded.text).toBe(JSON.stringify(candidate));
+    expect(encoded.bytes).toBe(
+      Buffer.byteLength(JSON.stringify(projectedResult(candidate))),
+    );
+  });
+
+  it("accounts for repeated Evidence representations", () => {
+    const normalized = { value: '中文"'.repeat(30000) };
+    const candidate = {
+      result: normalized,
+      evidence: { normalized_result: normalized },
+    };
+    const completeBytes = Buffer.byteLength(
+      JSON.stringify(projectedResult(candidate)),
+    );
+    expect(encodeToolResult(candidate, completeBytes).ok).toBe(true);
+    expect(encodeToolResult(candidate, completeBytes - 1)).toMatchObject({
+      ok: false,
+      bytesAtLeast: completeBytes,
+    });
+  });
+
+  it("stops before reading the remainder of an oversized result", () => {
+    const candidate: JsonValue = { text: "x".repeat(1000000) };
+    Object.defineProperty(candidate, "remainder", {
+      enumerable: true,
+      get() {
+        throw new Error("The remainder must not be read");
+      },
+    });
+    // Only an already-known first property is visited before exhausting the
+    // budget. The serializer's property discovery must not eagerly read values.
+    expect(() => encodeToolResult(candidate, 1000)).not.toThrow();
+    expect(encodeToolResult(candidate, 1000).ok).toBe(false);
+  });
+});