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fix(mcp-config-validator): stop flagging auto-injected + POSIX env vars

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Clears false positives on valid .mcp.json (gap matrix, Batch 1):
- ${CLAUDE_PROJECT_DIR} is auto-injected at runtime (CC 2.1.139) and never
  needs an env block — now allowlisted.
- POSIX expansions like ${VAR%pattern} / ${VAR:-default} are resolved by
  Claude Code (CC 2.1.142); the env-var regex now matches only bare
  ${IDENTIFIER}, so operator expressions are skipped.

Genuine bare unreferenced vars are still flagged (broken-project regression
intact). The MCP `trust` field is untouched — it is verify-first (point 4),
not part of Batch 1.

Tests: hermetic runtime temp-fixture; 23/23 MCP green, both directions covered.

Ref: docs/cc-2.1.x-gap-matrix.md

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ter3E2JSi1Khgmuf2kady8
This commit is contained in:
Kjell Tore Guttormsen 2026-06-18 12:03:21 +02:00
commit 4b94da0f11
2 changed files with 64 additions and 3 deletions
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58
tests/scanners/mcp-config-validator.test.mjs
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@ -1,7 +1,9 @@
import { describe, it, beforeEach } from 'node:test';
import { describe, it, beforeEach, afterEach } from 'node:test';
import assert from 'node:assert/strict';
import { resolve } from 'node:path';
import { resolve, join } from 'node:path';
import { fileURLToPath } from 'node:url';
import { mkdtemp, writeFile, rm } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import { resetCounter } from '../../scanners/lib/output.mjs';
import { discoverConfigFiles } from '../../scanners/lib/file-discovery.mjs';
import { scan } from '../../scanners/mcp-config-validator.mjs';
@ -101,6 +103,58 @@ describe('MCP scanner — broken project', () => {
});
});
describe('MCP scanner — env-var false positives (CC 2.1.139/2.1.142, Batch 1)', () => {
let tmpRoot;
let envFindings;
beforeEach(async () => {
resetCounter();
tmpRoot = await mkdtemp(join(tmpdir(), 'ca-mcp-env-'));
const mcp = {
mcpServers: {
proj: {
type: 'stdio',
command: 'node',
// CLAUDE_PROJECT_DIR is auto-injected (CC 2.1.139); ${VAR%…}/${VAR:-…}
// are POSIX expansions CC resolves (2.1.142) — none need an env block.
args: ['${CLAUDE_PROJECT_DIR}/server.mjs', '--root', '${HOME%/}', '--cfg', '${CONFIG_DIR:-/etc}'],
trust: 'workspace',
},
legacy: {
type: 'stdio',
command: 'node',
args: ['${REAL_MISSING}'],
trust: 'workspace',
},
},
};
await writeFile(join(tmpRoot, '.mcp.json'), JSON.stringify(mcp, null, 2) + '\n', 'utf8');
const discovery = await discoverConfigFiles(tmpRoot);
const result = await scan(tmpRoot, discovery);
envFindings = result.findings.filter(f => f.title === 'Unreferenced env var in args');
});
afterEach(async () => {
if (tmpRoot) await rm(tmpRoot, { recursive: true, force: true });
});
it('does NOT flag ${CLAUDE_PROJECT_DIR} (auto-injected runtime var)', () => {
const f = envFindings.find(x => /CLAUDE_PROJECT_DIR/.test(x.description || ''));
assert.equal(f, undefined, 'CLAUDE_PROJECT_DIR must be allowlisted');
});
it('does NOT flag POSIX expansions ${VAR%…} / ${VAR:-…}', () => {
const f = envFindings.find(x => /HOME|CONFIG_DIR/.test(x.description || ''));
assert.equal(f, undefined, 'POSIX operator expansions are not env-var references');
});
it('STILL flags a genuine bare unreferenced var', () => {
assert.equal(envFindings.length, 1,
`expected exactly REAL_MISSING; got: ${envFindings.map(f => f.description).join(' | ')}`);
assert.match(envFindings[0].description || '', /REAL_MISSING/);
});
});
describe('MCP scanner — empty project', () => {
let result;
beforeEach(async () => {