From 02bba8e9a641ce14559073db7db0a9335801df3e Mon Sep 17 00:00:00 2001
From: "developerz-ai[bot]"
 <286432749+developerz-ai[bot]@users.noreply.github.com>
Date: Tue, 22 Sep 2026 06:53:13 +0000
Subject: [PATCH] test(result): pin MAX_LIST_ITEMS, EVIDENCE_KEYS, MIME map,
 TRUNCATED_KEY, steering note
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The integration test in outer-tools.test.ts exercises these constants only
behaviorally — a swap of MAX_LIST_ITEMS from 20 to 21 would still pass the
existing 25-item array assertion. Export the four module-private constants
and assert their values directly so any future edit flips the unit test.

Dz-Task-Id: tsk_b9ddded8a73c1263efdb558e24d822c5
---
 src/mcp/tools/result.test.ts | 39 ++++++++++++++++++++++++++++++++++++
 src/mcp/tools/result.ts      |  8 ++++----
 2 files changed, 43 insertions(+), 4 deletions(-)
 create mode 100644 src/mcp/tools/result.test.ts

diff --git a/src/mcp/tools/result.test.ts b/src/mcp/tools/result.test.ts
new file mode 100644
index 0000000..8027a5f
--- /dev/null
+++ b/src/mcp/tools/result.test.ts
@@ -0,0 +1,39 @@
+import { expect, test } from 'bun:test';
+import {
+  EVIDENCE_KEYS,
+  MAX_LIST_ITEMS,
+  mimeTypeFor,
+  steeringNote,
+  TRUNCATED_KEY,
+} from './result.js';
+
+test('MAX_LIST_ITEMS is 20', () => {
+  expect(MAX_LIST_ITEMS).toBe(20);
+});
+
+test('EVIDENCE_KEYS contains exactly screenshot and evidence', () => {
+  expect(EVIDENCE_KEYS).toEqual(new Set(['screenshot', 'evidence']));
+});
+
+test('mimeTypeFor returns the expected MIME for each known extension', () => {
+  expect(mimeTypeFor('/tmp/x.png')).toBe('image/png');
+  expect(mimeTypeFor('/tmp/x.jpg')).toBe('image/jpeg');
+  expect(mimeTypeFor('/tmp/x.jpeg')).toBe('image/jpeg');
+  expect(mimeTypeFor('/tmp/x.mp4')).toBe('video/mp4');
+  expect(mimeTypeFor('/tmp/x.log')).toBe('text/plain');
+});
+
+test('mimeTypeFor returns undefined for an unknown extension', () => {
+  expect(mimeTypeFor('/tmp/x.txt')).toBeUndefined();
+});
+
+test('TRUNCATED_KEY is "truncated"', () => {
+  expect(TRUNCATED_KEY).toBe('truncated');
+});
+
+test('steeringNote contains the literal phrases for the capped fields', () => {
+  const note = steeringNote(['steps', 'bugs']);
+  expect(note).toContain('Truncated steps, bugs to the first 20 items');
+  expect(note).toContain('see "truncated" for the real totals');
+  expect(note).toContain('fields=["steps", "bugs"]');
+});
diff --git a/src/mcp/tools/result.ts b/src/mcp/tools/result.ts
index 0ffcbf5..9e8d0d4 100644
--- a/src/mcp/tools/result.ts
+++ b/src/mcp/tools/result.ts
@@ -26,15 +26,15 @@ function isRecord(value: unknown): value is Record<string, unknown> {
 }
 
 /** Cap on a top-level array field before it gets truncated for the response. */
-const MAX_LIST_ITEMS = 20;
+export const MAX_LIST_ITEMS = 20;
 
 /** Keys whose string value — when an absolute path — is evidence worth linking. */
-const EVIDENCE_KEYS = new Set(['screenshot', 'evidence']);
+export const EVIDENCE_KEYS = new Set(['screenshot', 'evidence']);
 
 type ResourceLinkContent = Extract<CallToolResult['content'][number], { type: 'resource_link' }>;
 
 /** Guess a MIME type from an evidence path's extension; omit when unknown. */
-function mimeTypeFor(path: string): string | undefined {
+export function mimeTypeFor(path: string): string | undefined {
   if (path.endsWith('.png')) return 'image/png';
   if (path.endsWith('.jpg') || path.endsWith('.jpeg')) return 'image/jpeg';
   if (path.endsWith('.mp4')) return 'video/mp4';
@@ -117,7 +117,7 @@ function capLists(data: Record<string, unknown>): {
 }
 
 /** Steering text appended when one or more lists got capped. */
-function steeringNote(truncated: string[]): string {
+export function steeringNote(truncated: string[]): string {
   const fields = truncated.map((f) => `"${f}"`).join(', ');
   return (
     `Truncated ${truncated.join(', ')} to the first ${MAX_LIST_ITEMS} items (see "${TRUNCATED_KEY}" ` +