fix(acr): conflict-detector segregates plugin-bundled configs (M-BUG-2)

CNF compared every discovered settings.json/hooks.json pairwise regardless of
origin, so it treated installed plugins' bundled configs — each plugin's own
settings.json/hooks.json plus its shipped test fixtures and examples under
~/.claude/plugins/ — as if they were the user's authored cascade. A "conflict"
between two plugins' bundled test fixtures is not something a user can resolve,
yet these dominated the count: 339 CNF findings on this machine (315 high-sev
permission allow/deny "conflicts", 18 duplicate-hook, 6 settings-key), almost all
sourced from plugin-internal fixtures. The Conflicts grade was F on pure noise.
Fix: CNF excludes any file whose path is under `.claude/plugins/` from conflict
analysis (new isPluginBundled predicate; absPath marker). Kept CNF-local rather
than a discovery-level skip on purpose: an active plugin's contributed
hooks.json/.mcp.json legitimately lives in plugins/cache and other scanners need
it — only conflict analysis must ignore plugin-bundled files. Same class as
M-BUG-8 (non-live config trees treated as live). Suite 1344/0 (+3: plugin-bundled
exclusion, discovery-side sanity, over-exclusion guard). Frozen v5.0.0 + SC-5
snapshots untouched (marketplace-medium has no plugins/ paths), no re-seed.
Dogfood ~/.claude CNF 339->0 (F-grade was 100% plugin-bundled noise; the ~3
genuine user-scope local settings have no actual conflicting keys, matching the
plan C5 "real surface ~3 files" prediction).

Follow-up (not in this fix): classifyScope tags plugin-bundled files by checking
basePath instead of the file's own path, so scope:'plugin' is effectively dead
for a ~/.claude-rooted scan. Fixing it would let every scanner trust the scope
field, but that is a discovery-layer change beyond this bug's scope.

tests/scanners/conflict-detector.test.mjs

@@ -1,6 +1,6 @@
 import { describe, it, beforeEach, before, after } from 'node:test';
 import assert from 'node:assert/strict';
-import { resolve, join } from 'node:path';
+import { resolve, join, sep } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { mkdir, writeFile, rm } from 'node:fs/promises';
 import { tmpdir } from 'node:os';
@@ -208,3 +208,98 @@ describe('CNF scanner — cache exclusion drops duplicate-hook count (B3)', () =
       `cache exclusion must drop CNF count: include=${includeCount} exclude=${excludeCount}`);
   });
 });
+
+// M-BUG-2: CNF must segregate plugin-bundled configs from the user's authored
+// cascade. Installed plugins ship their OWN settings.json / hooks.json — plus
+// bundled test fixtures and examples — under ~/.claude/plugins/. None of these
+// are user-authored config the user can edit, and a "conflict" between two
+// plugins' bundled files is not something the user can resolve. Yet CNF compared
+// every settings-json/hooks-json pairwise regardless of origin, inflating the
+// Conflicts grade to F with hundreds of bogus findings (339 on this machine,
+// ~315 of them high-severity permission "conflicts" between plugin test
+// fixtures). CNF must exclude any file whose path is under `.claude/plugins/`.
+// The exclusion belongs in CNF, NOT discovery: an active plugin's contributed
+// hooks.json/.mcp.json legitimately lives in plugins/cache and other scanners
+// need it — only conflict analysis must ignore it.
+describe('CNF scanner — excludes plugin-bundled configs (M-BUG-2)', () => {
+  let dir, result, discovery;
+
+  before(async () => {
+    dir = join(tmpdir(), `config-audit-cnf-mbug2-${Date.now()}`);
+    // Live, user-authored cascade (project-scope settings).
+    const liveClaude = join(dir, '.claude');
+    await mkdir(liveClaude, { recursive: true });
+    await writeFile(join(liveClaude, 'settings.json'), JSON.stringify({
+      model: 'opus',
+      permissions: { deny: ['Bash(curl:*)'] },
+      hooks: { PreToolUse: [{ matcher: 'Edit' }] },
+    }));
+    // An installed plugin ships its OWN settings.json + hooks.json (active version).
+    const p1 = join(liveClaude, 'plugins', 'cache', 'mkt', 'p1', '1.0.0');
+    await mkdir(join(p1, '.claude'), { recursive: true });
+    await writeFile(join(p1, '.claude', 'settings.json'), JSON.stringify({
+      model: 'sonnet',
+      permissions: { allow: ['Bash(curl:*)'] },
+      hooks: { PreToolUse: [{ matcher: 'Edit' }] },
+    }));
+    await mkdir(join(p1, 'hooks'), { recursive: true });
+    await writeFile(join(p1, 'hooks', 'hooks.json'), JSON.stringify({
+      hooks: { PreToolUse: [{ matcher: 'Edit' }] },
+    }));
+    // Another plugin ships a TEST FIXTURE settings.json — pure noise, never live.
+    const p2fix = join(liveClaude, 'plugins', 'cache', 'mkt', 'p2', '2.0.0',
+      'tests', 'fixtures', 'proj', '.claude');
+    await mkdir(p2fix, { recursive: true });
+    await writeFile(join(p2fix, 'settings.json'), JSON.stringify({
+      model: 'haiku',
+      permissions: { allow: ['Bash(rm:*)'] },
+    }));
+
+    resetCounter();
+    discovery = await discoverConfigFiles(dir);
+    result = await scan(dir, discovery);
+  });
+
+  after(async () => {
+    await rm(dir, { recursive: true, force: true });
+  });
+
+  it('discovery surfaces the plugin-bundled settings (exclusion must be CNF-side, not discovery-side)', () => {
+    const pluginSettings = discovery.files.filter(
+      f => f.type === 'settings-json' && f.absPath.includes(`.claude${sep}plugins${sep}`));
+    assert.ok(pluginSettings.length >= 2,
+      `expected ≥2 plugin-bundled settings discovered; got ${pluginSettings.length}`);
+  });
+
+  it('does not flag any conflict sourced from plugin-bundled configs', () => {
+    assert.equal(result.findings.length, 0,
+      `expected 0 CNF findings (only noise is plugin-bundled); got ${result.findings.length}: ${result.findings.map(f => f.title).join(', ')}`);
+  });
+});
+
+// Guard against over-exclusion: the fix must NOT silence genuine conflicts
+// between the user's own authored files (user/project/local), which are not
+// under `.claude/plugins/`.
+describe('CNF scanner — genuine live conflict still flagged (M-BUG-2 guard)', () => {
+  let dir, result;
+
+  before(async () => {
+    dir = join(tmpdir(), `config-audit-cnf-mbug2-guard-${Date.now()}`);
+    const claude = join(dir, '.claude');
+    await mkdir(claude, { recursive: true });
+    await writeFile(join(claude, 'settings.json'), JSON.stringify({ model: 'opus' }));
+    await writeFile(join(claude, 'settings.local.json'), JSON.stringify({ model: 'haiku' }));
+    resetCounter();
+    const discovery = await discoverConfigFiles(dir);
+    result = await scan(dir, discovery);
+  });
+
+  after(async () => {
+    await rm(dir, { recursive: true, force: true });
+  });
+
+  it('still flags the genuine cross-scope key conflict between user-authored files', () => {
+    assert.ok(result.findings.some(f => f.title.includes('model')),
+      `expected a genuine "model" conflict; got: ${result.findings.map(f => f.title).join(', ') || '(none)'}`);
+  });
+});