feat(voyage)!: marketplace handoff — rename plugins/ultraplan-local to plugins/voyage [skip-docs]

Session 5 of voyage-rebrand (V6). Operator-authorized cross-plugin scope.

- git mv plugins/ultraplan-local plugins/voyage (rename detected, history preserved)
- .claude-plugin/marketplace.json: voyage entry replaces ultraplan-local
- CLAUDE.md: voyage row in plugin list, voyage in design-system consumer list
- README.md: bulk rename ultra*-local commands -> trek* commands; ultraplan-local refs -> voyage; type discriminators (type: trekbrief/trekreview); session-title pattern (voyage:<command>:<slug>); v4.0.0 release-note paragraph
- plugins/voyage/.claude-plugin/plugin.json: homepage/repository URLs point to monorepo voyage path
- plugins/voyage/verify.sh: drop URL whitelist exception (no longer needed)

Closes voyage-rebrand. bash plugins/voyage/verify.sh PASS 7/7. npm test 361/361.

plugins/voyage/lib/validators/architecture-discovery.mjs

@@ -0,0 +1,94 @@
+// lib/validators/architecture-discovery.mjs
+// EXTERNAL CONTRACT — drift-WARN, never drift-FAIL.
+//
+// The architecture/ directory is owned by the separate `ultra-cc-architect`
+// plugin. ultraplan-local validates only DISCOVERY (file present at canonical
+// path) and tolerates internal-format drift via warnings.
+//
+// Never read body content beyond first heading. Never assert frontmatter shape.
+
+import { existsSync, readdirSync, statSync, readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { issue } from '../util/result.mjs';
+
+const CANONICAL_OVERVIEW = 'overview.md';
+const CANONICAL_GAPS = 'gaps.md';
+const KNOWN_ALTERNATIVES = ['architecture-overview.md', 'overview.markdown', 'README.md'];
+
+export function discoverArchitecture(projectDir) {
+  const archDir = projectDir ? join(projectDir, 'architecture') : null;
+  const result = {
+    found: false,
+    overview: null,
+    gaps: null,
+    looseFiles: [],
+    warnings: [],
+  };
+
+  if (!archDir || !existsSync(archDir) || !statSync(archDir).isDirectory()) {
+    return result;
+  }
+
+  const overviewPath = join(archDir, CANONICAL_OVERVIEW);
+  if (existsSync(overviewPath) && statSync(overviewPath).isFile()) {
+    result.found = true;
+    result.overview = overviewPath;
+  } else {
+    for (const alt of KNOWN_ALTERNATIVES) {
+      const altPath = join(archDir, alt);
+      if (existsSync(altPath) && statSync(altPath).isFile()) {
+        result.found = true;
+        result.overview = altPath;
+        result.warnings.push(issue(
+          'ARCH_NON_CANONICAL_OVERVIEW',
+          `Architecture file at non-canonical path: ${alt}`,
+          `Canonical contract is architecture/overview.md. The ultra-cc-architect plugin may have drifted; this is a warning, not a blocker.`,
+        ));
+        break;
+      }
+    }
+  }
+
+  const gapsPath = join(archDir, CANONICAL_GAPS);
+  if (existsSync(gapsPath) && statSync(gapsPath).isFile()) result.gaps = gapsPath;
+
+  const all = readdirSync(archDir).filter(f => /\.md$/i.test(f));
+  result.looseFiles = all
+    .filter(f => f !== CANONICAL_OVERVIEW && f !== CANONICAL_GAPS && !KNOWN_ALTERNATIVES.includes(f))
+    .map(f => join(archDir, f));
+
+  if (result.looseFiles.length > 0) {
+    result.warnings.push(issue(
+      'ARCH_LOOSE_FILES',
+      `Found ${result.looseFiles.length} unrecognized architecture file(s)`,
+      `Architecture contract expects overview.md (+ optional gaps.md). Loose files may indicate format drift in ultra-cc-architect.`,
+    ));
+  }
+
+  if (result.found && result.overview) {
+    try {
+      const text = readFileSync(result.overview, 'utf-8');
+      const firstHeading = text.match(/^#\s+(.+?)\s*$/m);
+      result.firstHeading = firstHeading ? firstHeading[1] : null;
+    } catch { /* ignore — only sniff */ }
+  }
+
+  return result;
+}
+
+if (import.meta.url === `file://${process.argv[1]}`) {
+  const projectDir = process.argv[2];
+  const wantJson = process.argv.includes('--json');
+  if (!projectDir) {
+    process.stderr.write('Usage: architecture-discovery.mjs <project-dir> [--json]\n');
+    process.exit(2);
+  }
+  const r = discoverArchitecture(projectDir);
+  if (wantJson) {
+    process.stdout.write(JSON.stringify(r, null, 2) + '\n');
+  } else {
+    process.stdout.write(`architecture-discovery: ${r.found ? 'FOUND' : 'NONE'} ${r.overview || projectDir}\n`);
+    for (const w of r.warnings) process.stderr.write(`  WARN   [${w.code}] ${w.message}\n`);
+  }
+  process.exit(0);
+}