fix: surface tool errors before formatter routing; render libraries topUsed

P1: tools return { status: 'error', message } without setting isError on
the MCP envelope. formatJson now detects this before routing to a command
formatter, which would otherwise render a misleading empty box.

P2: get_team_patterns --category libraries returns topUsed instead of
patterns. Add LibraryEntry type, make PatternResponse.patterns optional,
and render topUsed in formatPatterns under a TOP LIBRARIES section.

Author: PatrickSys

src/cli-formatters.ts

@@ -7,6 +7,7 @@ import path from 'path';
 import type {
   PatternResponse,
   PatternEntry,
+  LibraryEntry,
   SearchResponse,
   SearchResultItem,
   RefsResponse,
@@ -153,6 +154,18 @@ export function formatPatterns(data: PatternResponse): void {
     }
   }
 
+  const topUsed = data.topUsed;
+  if (topUsed && topUsed.length > 0) {
+    lines.push('');
+    lines.push('\u2500'.repeat(66));
+    lines.push('');
+    lines.push('TOP LIBRARIES');
+    for (const lib of topUsed.slice(0, 15) as LibraryEntry[]) {
+      const src = padRight(lib.source ?? '', 52);
+      lines.push(`  ${src} ${lib.count} imports`);
+    }
+  }
+
   if (goldenFiles && goldenFiles.length > 0) {
     lines.push('');
     lines.push('\u2500'.repeat(66));
@@ -607,6 +620,16 @@ export function formatJson(
     return;
   }
 
+  // Tools return { status: 'error', message: '...' } in their JSON payload but
+  // don't always set isError on the MCP envelope. Route these to stderr before
+  // a command formatter would render a misleading empty box.
+  if (typeof data === 'object' && data !== null && (data as Record<string, unknown>).status === 'error') {
+    const d = data as Record<string, unknown>;
+    const msg = typeof d.message === 'string' ? d.message : JSON.stringify(d, null, 2);
+    process.stderr.write(`Error: ${msg}\n`);
+    return;
+  }
+
   switch (command) {
     case 'metadata': {
       try {

src/tools/types.ts

@@ -105,11 +105,17 @@ export interface GoldenFile {
   score: number;
 }
 
+export interface LibraryEntry {
+  source: string;
+  count: number;
+}
+
 export interface PatternResponse {
-  patterns: Record<string, PatternCategory>;
+  patterns?: Record<string, PatternCategory>;
   goldenFiles?: GoldenFile[];
   memories?: Array<{ type: string; memory: string }>;
   conflicts?: PatternConflict[];
+  topUsed?: LibraryEntry[];
 }
 
 // --- Metadata response types ---