fix(cli): report unsupported-language projects instead of finishing silently (#1806)

A project CodeGraph has no grammar for was indistinguishable from an empty one: unsupported extensions are filtered out at discovery, so filesDiscovered was 0, the reconciliation in index.ts found no shortfall and recorded index_state as complete, and the CLI printed the same 'No files found to index' it prints for an empty repo.

That silence is what makes it costly over MCP: an empty result reads identically to 'no match', and the agent has been told to trust the graph rather than grep.

The scan already visits every file, so the tally of what it declined to index costs no extra I/O and no second pass. index_state itself is left alone: changing its values would change the status --json contract, which is a call for the maintainer to make.


(cherry picked from commit 2c20892789897f502f84152f78b777b11d65fdaa)

Co-authored-by: Max Hsu <maxmilian@gmail.com>
Co-authored-by: netbrah <netbrah@users.noreply.github.com>

__tests__/extraction.test.ts

@@ -8,8 +8,9 @@ import { describe, it, expect, beforeAll, beforeEach, afterEach } from 'vitest';
 import * as fs from 'fs';
 import * as path from 'path';
 import * as os from 'os';
+import { execFileSync } from 'child_process';
 import { CodeGraph } from '../src';
-import { extractFromSource, scanDirectory, buildDefaultIgnore, discoverEmbeddedRepoRoots, buildScopeIgnore } from '../src/extraction';
+import { extractFromSource, scanDirectory, scanDirectoryAsync, buildDefaultIgnore, discoverEmbeddedRepoRoots, buildScopeIgnore, type ScanSkipStats } from '../src/extraction';
 import { detectLanguage, isLanguageSupported, getSupportedLanguages, initGrammars, loadAllGrammars, isSourceFile } from '../src/extraction/grammars';
 import { stripCppTemplateArgs, blankCppExportMacros, blankCppInlineMacros, blankMetalAttributes, blankCudaConstructs, blankCppAnnotationMacroCalls, blankCppApiPrefixMacros, blankCppInlineAnnotationMacros, blankCLeadingAttrMacros, recoverMangledCppName } from '../src/extraction/languages/c-cpp';
 import { normalizePath } from '../src/utils';
@@ -12721,3 +12722,63 @@ describe('C/C++ kernel-port preParse blanks (R7a)', () => {
     expect(result.nodes.some((n) => n.kind === 'method' && n.name === 'size')).toBe(true);
   });
 });
+
+// `init` on a project CodeGraph has no grammar for used to look identical to a
+// successful index of an empty repo: 0 files, `index_state: complete`, exit 0.
+// Nothing said "there are 24k files here and I understood none of them", so an
+// agent told to trust the graph concluded the code did not exist (#1502).
+//
+// The scan already visits every file, so the count comes from the walk it
+// already does — no second pass.
+describe('Unsupported-language projects report what they skipped (#1502)', () => {
+  let tempDir: string;
+
+  beforeEach(() => {
+    tempDir = createTempDir();
+  });
+
+  it('counts files it could not index, by extension, on the git path', async () => {
+    const runGit = (...args: string[]) =>
+      execFileSync('git', args, { cwd: tempDir, stdio: 'pipe' });
+    fs.mkdirSync(tempDir, { recursive: true });
+    runGit('init', '-q');
+    runGit('config', 'user.email', 'test@test.com');
+    runGit('config', 'user.name', 'Test');
+    fs.writeFileSync(path.join(tempDir, 'a.move'), 'module a {}');
+    fs.writeFileSync(path.join(tempDir, 'b.move'), 'module b {}');
+    fs.writeFileSync(path.join(tempDir, 'c.pl'), 'print 1;');
+    runGit('add', '-A');
+    runGit('commit', '-q', '-m', 'unsupported only');
+
+    const stats: ScanSkipStats = { unsupportedByExtension: new Map() };
+    const files = await scanDirectoryAsync(tempDir, undefined, stats);
+
+    expect(files).toEqual([]);
+    expect(stats.unsupportedByExtension.get('.move')).toBe(2);
+    expect(stats.unsupportedByExtension.get('.pl')).toBe(1);
+  });
+
+  it('counts them on the filesystem-walk path too (non-git project)', async () => {
+    fs.mkdirSync(tempDir, { recursive: true });
+    fs.writeFileSync(path.join(tempDir, 'a.move'), 'module a {}');
+    fs.writeFileSync(path.join(tempDir, 'b.pl'), 'print 1;');
+
+    const stats: ScanSkipStats = { unsupportedByExtension: new Map() };
+    const files = await scanDirectoryAsync(tempDir, undefined, stats);
+
+    expect(files).toEqual([]);
+    expect(stats.unsupportedByExtension.get('.move')).toBe(1);
+    expect(stats.unsupportedByExtension.get('.pl')).toBe(1);
+  });
+
+  it('stays silent when every file was indexable', async () => {
+    fs.mkdirSync(tempDir, { recursive: true });
+    fs.writeFileSync(path.join(tempDir, 'a.ts'), 'export const a = 1;');
+
+    const stats: ScanSkipStats = { unsupportedByExtension: new Map() };
+    const files = await scanDirectoryAsync(tempDir, undefined, stats);
+
+    expect(files).toEqual(['a.ts']);
+    expect(stats.unsupportedByExtension.size).toBe(0);
+  });
+});