fix(cli): do not call zero-symbol detect-changes a clean tree (#3138)

* fix(cli): do not call zero-symbol detect-changes a clean tree

Print backend summary.message and distinguish a parsed diff with no overlapping indexed symbols from an empty git diff. Pin --color=never so color.ui=always cannot hide +++ b/ headers.

* fix(cli): localize clean-tree detect-changes and skip no-overlap when partial

Production empty diffs carry English summary.message; route that through t() so zh-CN fires. Do not claim no indexed-symbol overlap on queryDegraded partial results. Pin formatter tests to en and cover the production payload shapes.

* fix(cli): prettier detect-changes-format and degraded eval assertion

---------

Co-authored-by: Gergő Magyar <gergomagyar@icloud.com>

gitnexus/src/cli/detect-changes-format.ts

@@ -6,6 +6,7 @@ type DetectChangesSummary = {
   changed_count?: number;
   affected_count?: number;
   risk_level?: string;
+  message?: string;
 };
 
 type ChangedSymbol = {
@@ -55,6 +56,29 @@ export function formatDetectChangesResult(result: unknown): string {
     );
 
   if ((summary.changed_count ?? 0) === 0) {
+    // Parse-fail payloads set `partial` and an honest `message` (#2915/#3131).
+    // Production *clean* trees also set English `message: 'No changes detected.'`
+    // — that must go through `t('tool.detectChanges.noChanges')` or zh-CN never
+    // fires. Only pass the backend string through on a degraded/parse-fail run.
+    if (
+      payload.partial &&
+      typeof summary.message === 'string' &&
+      summary.message.trim().length > 0
+    ) {
+      return [...notes, summary.message.trim()].join('\n');
+    }
+    // Confirmed no-overlap: files parsed, mapping succeeded, zero symbols.
+    // `queryDegraded` is `partial: true` with the same counts and no message —
+    // do not call that a confirmed mapping (#3131 honesty).
+    if (!payload.partial && (summary.changed_files ?? 0) > 0) {
+      return [
+        ...notes,
+        t('tool.detectChanges.noOverlappingSymbols', { files: summary.changed_files }),
+      ].join('\n');
+    }
+    if (payload.partial) {
+      return notes.join('\n');
+    }
     return [...notes, t('tool.detectChanges.noChanges')].join('\n');
   }
 

gitnexus/src/cli/i18n/en.ts

@@ -76,6 +76,8 @@ export const en = {
   'tool.warn.unknownKind':
     "--kind '{{kind}}' is not a known symbol kind (e.g. Function, Class, Method); it will not narrow the result.",
   'tool.detectChanges.noChanges': 'No changes detected.',
+  'tool.detectChanges.noOverlappingSymbols':
+    'Diff touched {{files}} file(s) but no indexed symbols overlap those hunks — not a clean tree.',
   'tool.detectChanges.partial':
     'PARTIAL RESULT: a graph query failed, so changed symbols may be missing. Do not read this as a clean pre-commit check.',
   'tool.detectChanges.truncated':

gitnexus/src/cli/i18n/zh-CN.ts

@@ -78,6 +78,8 @@ export const zhCN = {
   'tool.warn.unknownKind':
     "--kind '{{kind}}' 不是已知的符号类型（如 Function、Class、Method），不会用于缩小结果范围。",
   'tool.detectChanges.noChanges': '未检测到变更。',
+  'tool.detectChanges.noOverlappingSymbols':
+    'diff 触及 {{files}} 个文件，但没有索引符号与这些 hunk 重叠 — 并非干净工作区。',
   'tool.detectChanges.partial':
     '结果不完整：图查询失败，可能遗漏已变更符号。请勿将其视为通过的提交前检查。',
   'tool.detectChanges.truncated':

gitnexus/src/mcp/local/local-backend.ts

@@ -988,6 +988,9 @@ export function buildDetectChangesDiffArgs(scope: string, baseRef?: string): str
     'diff',
     '--ignore-cr-at-eol',
     '--no-ext-diff',
+    // color.ui=always prefixes `+++ b/` with ANSI, so parseDiffHunks sees zero
+    // files and the CLI used to print a clean "No changes detected." (#3131).
+    '--color=never',
     '--src-prefix=a/',
     '--dst-prefix=b/',
   ];

gitnexus/test/unit/detect-changes-eol.test.ts

@@ -8,11 +8,12 @@ import { parseDiffHunks } from '../../src/storage/git.js';
 import { diffArgsFor } from '../helpers/detect-changes-diff-args.js';
 import { commitAll, initGitRepo } from '../helpers/temp-git-repo.js';
 
-/** The five flags every scope carries, ahead of its own ref/staging arguments. */
+/** The six flags every scope carries, ahead of its own ref/staging arguments. */
 const GUARD_FLAGS = [
   'diff',
   '--ignore-cr-at-eol',
   '--no-ext-diff',
+  '--color=never',
   '--src-prefix=a/',
   '--dst-prefix=b/',
 ];

gitnexus/test/unit/detect-changes-format.test.ts

@@ -0,0 +1,92 @@
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { formatDetectChangesResult } from '../../src/cli/detect-changes-format.js';
+import { setCliLanguage } from '../../src/cli/i18n/index.js';
+
+describe('formatDetectChangesResult — zero-symbol honesty (#3131)', () => {
+  beforeEach(() => {
+    setCliLanguage('en');
+  });
+
+  afterEach(() => {
+    setCliLanguage(null);
+  });
+
+  it('prints backend parse-fail message instead of a generic all-clear', () => {
+    const text = formatDetectChangesResult({
+      partial: true,
+      summary: {
+        changed_count: 0,
+        affected_count: 0,
+        risk_level: 'unknown',
+        message: 'Could not parse the git diff output — no file headers recognised.',
+      },
+    });
+    expect(text).toContain('PARTIAL RESULT');
+    expect(text).toContain('Could not parse the git diff output');
+    expect(text).not.toContain('No changes detected.');
+  });
+
+  it('does not call a parsed diff with no symbol overlap a clean tree', () => {
+    const text = formatDetectChangesResult({
+      summary: {
+        changed_count: 0,
+        affected_count: 0,
+        changed_files: 1,
+        risk_level: 'low',
+      },
+    });
+    expect(text).toMatch(/Diff touched 1 file/);
+    expect(text).not.toContain('No changes detected.');
+    expect(text).not.toContain('PARTIAL RESULT');
+  });
+
+  it('does not claim no-overlap when a degraded query left changed_count at zero', () => {
+    const text = formatDetectChangesResult({
+      partial: true,
+      summary: {
+        changed_count: 0,
+        affected_count: 0,
+        changed_files: 1,
+        risk_level: 'unknown',
+      },
+    });
+    expect(text).toContain('PARTIAL RESULT');
+    expect(text).not.toMatch(/no indexed symbols overlap/i);
+    expect(text).not.toContain('No changes detected.');
+  });
+
+  it('keeps the clean-tree sentence only when git produced no files', () => {
+    const text = formatDetectChangesResult({
+      summary: { changed_count: 0, affected_count: 0, changed_files: 0, risk_level: 'none' },
+    });
+    expect(text).toBe('No changes detected.');
+  });
+
+  it('localizes the production clean-tree payload that carries English summary.message', () => {
+    setCliLanguage('zh-CN');
+    const text = formatDetectChangesResult({
+      summary: {
+        changed_count: 0,
+        affected_count: 0,
+        risk_level: 'none',
+        message: 'No changes detected.',
+      },
+    });
+    expect(text).toBe('未检测到变更。');
+  });
+
+  it('localizes confirmed no-overlap under GITNEXUS_LANG=zh-CN', () => {
+    setCliLanguage('zh-CN');
+    const text = formatDetectChangesResult({
+      summary: {
+        changed_count: 0,
+        affected_count: 0,
+        changed_files: 1,
+        risk_level: 'low',
+      },
+    });
+    expect(text).toContain('diff 触及 1 个文件');
+    expect(text).not.toContain('未检测到变更。');
+    expect(text).not.toContain('No changes detected.');
+  });
+});

gitnexus/test/unit/eval-formatters.test.ts

@@ -604,7 +604,8 @@ describe('formatDetectChangesResult', () => {
     // counts at zero. Without the note the pre-commit gate reads as "clean".
     const result = formatDetectChangesResult({ partial: true, summary: { changed_count: 0 } });
     expect(result).toContain('PARTIAL RESULT');
-    expect(result).toContain('No changes detected.');
+    expect(result).toContain('a graph query failed');
+    expect(result).not.toContain('No changes detected.');
   });
 
   it('flags a degraded run that still found symbols', () => {