perf: replace O(N·chunks) listForRadar read path with O(N·agents) metrics lookup

listForRadar previously called findByAgentIds() and JSON-parsed every chunk to
compute questionsCount, subagentsCount, and compactionsCount. Switch to
findMetricsByAgentIds() which reads the pre-computed agent_metrics table,
eliminating the chunk scan and per-row JSON.parse entirely.

Add two new test cases: agent with no metrics row returns zero counts, and
listForRadar response rows never carry chunk content.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/server/test/unit/radar-procedures.test.ts

@@ -325,6 +325,47 @@ describe('agent.listForRadar', () => {
     expect(row!.subagentsCount).toBe(0);
     expect(row!.compactionsCount).toBe(0);
   });
+
+  it('returns zero counts for agent with no metrics row', async () => {
+    const agents = new MockAgentManager();
+    const ctx = makeCtx(agents);
+
+    const now = new Date();
+    // Agent with no log chunks at all — no agent_metrics row will exist
+    agents.addAgent({ id: 'agent-no-chunks', name: 'no-chunks-agent', status: 'running', createdAt: now });
+
+    const caller = createAgentCaller(ctx);
+    const result = await caller.listForRadar({ timeRange: 'all' });
+
+    const row = result.find(r => r.id === 'agent-no-chunks');
+    expect(row).toBeDefined();
+    expect(row!.questionsCount).toBe(0);
+    expect(row!.subagentsCount).toBe(0);
+    expect(row!.compactionsCount).toBe(0);
+  });
+
+  it('listForRadar response does not contain chunk content field', async () => {
+    const agents = new MockAgentManager();
+    const ctx = makeCtx(agents);
+    const { logChunkRepo } = getRepos(ctx);
+
+    const now = new Date();
+    agents.addAgent({ id: 'agent-content', name: 'content-agent', status: 'running', createdAt: now });
+
+    await logChunkRepo.insertChunk({
+      agentId: 'agent-content',
+      agentName: 'content-agent',
+      sessionNumber: 1,
+      content: JSON.stringify({ type: 'tool_use', name: 'Agent', input: { description: 'do stuff', prompt: 'some prompt' } }),
+    });
+
+    const caller = createAgentCaller(ctx);
+    const result = await caller.listForRadar({ timeRange: 'all' });
+
+    for (const row of result) {
+      expect(row).not.toHaveProperty('content');
+    }
+  });
 });
 
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