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.ts

@@ -0,0 +1,55 @@
+import { STDIO_DEFAULT_MAX_BUFFER_SIZE } from "@modelcontextprotocol/server";
+import { constants as bufferConstants } from "node:buffer";
+
+import type { JsonValue } from "../domain/jsonValue.js";
+import { bufferedJsonParts, jsonParts } from "../domain/jsonSerialization.js";
+
+// Leave room for the SDK's JSON-RPC envelope and protocol metadata. This budget
+// follows the pinned client's actual default framing limit, not a result-row cap.
+export const MCP_RESULT_BUDGET_BYTES = STDIO_DEFAULT_MAX_BUFFER_SIZE - 1024;
+export const MCP_RESULT_STRING_LIMIT = bufferConstants.MAX_STRING_LENGTH - 1024;
+
+const RESULT_ENVELOPE_BYTES =
+  Buffer.byteLength(
+    JSON.stringify({
+      content: [{ type: "text", text: "" }],
+      structuredContent: null,
+    }),
+  ) - 4;
+
+/** Result of encoding the complete repeated MCP representations within a wire budget. */
+export type ToolResultEncoding =
+  | { readonly ok: true; readonly text: string; readonly bytes: number }
+  | {
+      readonly ok: false;
+      readonly bytesAtLeast: number;
+      readonly codeUnitsAtLeast: number;
+      readonly constraint: "receive-buffer" | "string-length";
+    };
+
+/** Account for structured JSON and escaped text before allocating the complete text. */
+export const encodeToolResult = (
+  value: JsonValue,
+  budgetBytes = MCP_RESULT_BUDGET_BYTES,
+): ToolResultEncoding => {
+  const parts: string[] = [];
+  let bytes = RESULT_ENVELOPE_BYTES;
+  let codeUnits = RESULT_ENVELOPE_BYTES;
+  for (const part of bufferedJsonParts(jsonParts(value))) {
+    const escapedPart = JSON.stringify(part);
+    bytes += Buffer.byteLength(part) + Buffer.byteLength(escapedPart) - 2;
+    codeUnits += part.length + escapedPart.length - 2;
+    if (bytes > budgetBytes || codeUnits > MCP_RESULT_STRING_LIMIT)
+      return {
+        ok: false,
+        bytesAtLeast: bytes,
+        codeUnitsAtLeast: codeUnits,
+        constraint:
+          codeUnits > MCP_RESULT_STRING_LIMIT
+            ? "string-length"
+            : "receive-buffer",
+      };
+    parts.push(part);
+  }
+  return { ok: true, text: parts.join(""), bytes };
+};