feat(cli,core): expand provider ecosystem with Antigravity and Gemma

- Add Antigravity (Light Blue) and Gemma (Gemini Blue) providers
- Update Gemini CLI brand color to Purple
- Implement personality overlays for Antigravity and Gemma in core
- Ensure brand-accurate labels and colors across Marketplace and Status Bar
- Add unit tests for new provider personality overlays

packages/core/src/agents/agentLoader.ts

@@ -211,7 +211,7 @@ const remoteAgentSchema = z.union([
 
 type FrontmatterRemoteAgentDefinition = z.infer<typeof remoteAgentSchema>;
 
-const externalAgentSchema = z
+export const externalAgentSchema = z
   .object({
     kind: z.literal('external'),
     name: nameSchema,

packages/core/src/agents/external-invocation.test.ts

@@ -76,6 +76,30 @@ describe('ExternalAgentInvocation', () => {
     );
   });
 
+  it('should support Antigravity provider', () => {
+    const antigravityDef: ExternalAgentDefinition = {
+      ...externalDef,
+      provider: 'antigravity',
+    };
+    const polyfilled = polyfillExternalAgent(antigravityDef);
+
+    expect(polyfilled.promptConfig.systemPrompt).toContain(
+      'Antigravity Personality Overlay',
+    );
+  });
+
+  it('should support Gemma provider', () => {
+    const gemmaDef: ExternalAgentDefinition = {
+      ...externalDef,
+      provider: 'gemma',
+    };
+    const polyfilled = polyfillExternalAgent(gemmaDef);
+
+    expect(polyfilled.promptConfig.systemPrompt).toContain(
+      'Gemma Personality Overlay',
+    );
+  });
+
   it('should include styleInstructions from providerConfig', () => {
     const customDef: ExternalAgentDefinition = {
       ...externalDef,

packages/core/src/agents/external-invocation.ts

@@ -101,6 +101,24 @@ You are acting as the "Codex" agent, a specialized code generation model.
 - Focus on generating high-quality, idiomatic, and correct code for the requested task.
 - Prioritize structural integrity and idiomatic patterns for the target language.
 - Provide clear, well-documented code snippets.
+${styleInstructions}`.trim();
+
+    case 'antigravity':
+      return `
+# Antigravity Personality Overlay
+You are acting as the "Antigravity" agent.
+- Focus on creative problem solving and thinking "outside the box".
+- Adopt a playful but highly competent engineering persona.
+- Encourage unconventional but effective solutions.
+${styleInstructions}`.trim();
+
+    case 'gemma':
+      return `
+# Gemma Personality Overlay
+You are acting as the "Gemma" agent, an open, lightweight, and capable model.
+- Focus on accessibility and efficiency.
+- Provide helpful, clear, and easy-to-understand explanations.
+- Maintain a friendly and supportive persona.
 ${styleInstructions}`.trim();
 
     default:

packages/core/src/agents/teamLoader.ts

@@ -11,7 +11,12 @@ import * as path from 'node:path';
 import * as crypto from 'node:crypto';
 import { z } from 'zod';
 import { type TeamDefinition } from './types.js';
-import { AgentLoadError, loadAgentsFromDirectory } from './agentLoader.js';
+import {
+  AgentLoadError,
+  loadAgentsFromDirectory,
+  externalAgentSchema,
+  markdownToAgentDefinition,
+} from './agentLoader.js';
 import { FRONTMATTER_REGEX } from '../skills/skillLoader.js';
 import { getErrorMessage } from '../utils/errors.js';
 
@@ -32,6 +37,7 @@ const teamSchema = z
     name: nameSchema,
     display_name: z.string().min(1),
     description: z.string().min(1),
+    agents: z.array(externalAgentSchema).optional(),
   })
   .strict();
 
@@ -121,18 +127,45 @@ export async function loadTeamsFromDirectory(
         );
       }
 
-      const { name, display_name, description } = parsedFrontmatter.data;
+      const {
+        name,
+        display_name,
+        description,
+        agents: inlineAgentsRaw,
+      } = parsedFrontmatter.data;
 
       // Load agents from agents/ subfolder
       const agentsResult = await loadAgentsFromDirectory(agentsDirPath);
       result.errors.push(...agentsResult.errors);
 
+      const allAgents = [...agentsResult.agents];
+
+      // Add inline agents
+      if (inlineAgentsRaw) {
+        for (const inline of inlineAgentsRaw) {
+          try {
+            const agent = markdownToAgentDefinition(inline, {
+              hash,
+              filePath: teamMdPath,
+            });
+            allAgents.push(agent);
+          } catch (error) {
+            result.errors.push(
+              new AgentLoadError(
+                teamMdPath,
+                `Error loading inline agent "${inline.name}": ${getErrorMessage(error)}`,
+              ),
+            );
+          }
+        }
+      }
+
       result.teams.push({
         name,
         displayName: display_name,
         description,
         instructions,
-        agents: agentsResult.agents,
+        agents: allAgents,
         metadata: {
           hash,
           filePath: teamMdPath,