fix(config): consolidate providers and agent definitions

- Disable google-vertex and google-vertex-anthropic (redundant with Antigravity)
- Remove non-working antigravity provider config
- Use built-in antigravity-* models from provider.ts
- Add zee, stanley, johny agent definitions
- Update compaction to use google/antigravity-gemini-3-flash
- Update johny.md to use google/antigravity-claude-opus-4-5-thinking
- Remove top_p from agent files (handled by ProviderTransform)
- Add docs/PROVIDERS.md with provider setup documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.agent-core/agent-core.jsonc

@@ -3,6 +3,7 @@
   "model": "cerebras/qwen-3-235b-a22b-instruct-2507",
   "small_model": "cerebras/gpt-oss-120b",
   "default_agent": "zee",
+  "disabled_providers": ["google-vertex", "google-vertex-anthropic"],
   "instructions": ["STYLE_GUIDE.md"],
   "mcp": {
     "context7": {
@@ -42,64 +43,33 @@
           }
         }
       }
-    },
-    "antigravity": {
-      "name": "Google Antigravity",
-      "api": "https://antigravity.opencode.ai/v1",
-      "npm": "@ai-sdk/openai-compatible",
-      "env": ["GOOGLE_OAUTH_TOKEN"],
-      "models": {
-        "claude-opus-4-5": {
-          "name": "Claude Opus 4.5 (via Antigravity)",
-          "release_date": "2025-01-01",
-          "temperature": true,
-          "reasoning": false,
-          "tool_call": true,
-          "attachment": true,
-          "limit": {
-            "context": 200000,
-            "output": 8192
-          },
-          "modalities": {
-            "input": ["text", "image"],
-            "output": ["text"]
-          },
-          "cost": {
-            "input": 15,
-            "output": 75
-          }
-        },
-        "gemini-3-flash": {
-          "name": "Gemini 3 Flash (via Antigravity)",
-          "release_date": "2025-01-01",
-          "temperature": true,
-          "reasoning": false,
-          "tool_call": true,
-          "attachment": true,
-          "limit": {
-            "context": 1000000,
-            "output": 8192
-          },
-          "modalities": {
-            "input": ["text", "image", "video", "audio", "pdf"],
-            "output": ["text"]
-          },
-          "cost": {
-            "input": 0.1,
-            "output": 0.4
-          }
-        }
-      }
     }
   },
   "agent": {
+    "zee": {
+      "description": "Personal assistant for life admin, memory, messaging, and calendar",
+      "mode": "primary",
+      "color": "#5c9cf5"
+    },
+    "stanley": {
+      "description": "Investing and financial research assistant",
+      "mode": "primary",
+      "color": "#f5a742"
+    },
+    "johny": {
+      "description": "Study assistant for learning and knowledge graphs",
+      "mode": "primary",
+      "color": "#7fd88c"
+    },
     "title": {
       "model": "cerebras/gpt-oss-120b",
-      "temperature": 0.5
+      "temperature": 0.5,
+      "hidden": true
     },
     "compaction": {
-      "model": "antigravity/gemini-3-flash",
-      "temperature": 0.3
+      "model": "google/antigravity-gemini-3-flash",
+      "temperature": 0.3,
+      "hidden": true
     }
   }
 }

.agent-core/agent/johny.md

@@ -1,9 +1,8 @@
 ---
 description: Learning system - study, knowledge graph, spaced repetition
 color: "#DC2626"
-model: antigravity/claude-opus-4-5
+model: google/antigravity-claude-opus-4-5-thinking
 temperature: 0.8
-top_p: 0.9
 ---
 
 # Johny - Learning System

.agent-core/agent/stanley.md

@@ -3,7 +3,6 @@ description: Investing system - markets, portfolio, SEC filings, NautilusTrader
 color: "#059669"
 model: openrouter/x-ai/grok-4.1-fast
 temperature: 0.7
-top_p: 0.85
 ---
 
 # Stanley - Investing System

docs/PROVIDERS.md

@@ -0,0 +1,101 @@
+# Provider Configuration
+
+This document describes the working provider setup for agent-core.
+
+## Config Locations
+
+| Type | Location |
+|------|----------|
+| Project config | `~/.local/src/agent-core/.agent-core/agent-core.jsonc` |
+| Global config (symlink) | `~/.config/agent-core/agent-core.jsonc` |
+| Agent definitions | `~/.local/src/agent-core/.agent-core/agent/` |
+| Global agents (symlink) | `~/.config/agent-core/agent/` |
+
+The global config is symlinked to project config so changes in one location reflect in both.
+
+## Providers
+
+### Google (Antigravity)
+
+Free-tier models via the `opencode-antigravity-auth` plugin.
+
+**Provider ID:** `google`
+
+**Available Models:**
+| Model ID | Display Name | Type |
+|----------|--------------|------|
+| `google/antigravity-claude-opus-4-5-thinking` | Claude Opus 4.5 Thinking | Reasoning |
+| `google/antigravity-claude-sonnet-4-5` | Claude Sonnet 4.5 | Standard |
+| `google/antigravity-claude-sonnet-4-5-thinking` | Claude Sonnet 4.5 Thinking | Reasoning |
+| `google/antigravity-gemini-3-pro` | Gemini 3 Pro | Reasoning |
+| `google/antigravity-gemini-3-flash` | Gemini 3 Flash | Fast |
+
+**Notes:**
+- Models are hardcoded in `provider.ts` and auto-loaded when the antigravity plugin detects auth
+- Opus 4.5 is only available as the `-thinking` variant
+- Thinking models require `topP >= 0.95` (handled automatically by ProviderTransform)
+
+### Cerebras
+
+**Provider ID:** `cerebras`
+
+**Custom Models (defined in config):**
+| Model ID | Display Name |
+|----------|--------------|
+| `cerebras/zai-glm-4.7` | GLM-4.7 (Z.AI on Cerebras) |
+
+**Environment:** `CEREBRAS_API_KEY`
+
+### OpenRouter
+
+**Provider ID:** `openrouter`
+
+**Environment:** `OPENROUTER_API_KEY`
+
+Access to various models including Grok, Llama, etc.
+
+## Disabled Providers
+
+These are disabled in `agent-core.jsonc`:
+- `google-vertex` - Direct Vertex AI (redundant with Antigravity)
+- `google-vertex-anthropic` - Vertex Claude (redundant with Antigravity)
+
+## Agent Defaults
+
+| Agent | Default Model | Purpose |
+|-------|---------------|---------|
+| Zee | `cerebras/zai-glm-4.7` | Personal assistant |
+| Stanley | `openrouter/x-ai/grok-4.1-fast` | Investing assistant |
+| Johny | `google/antigravity-claude-opus-4-5-thinking` | Learning assistant |
+| title | `cerebras/gpt-oss-120b` | Conversation titles (hidden) |
+| compaction | `google/antigravity-gemini-3-flash` | Context compaction (hidden) |
+
+## Auth Storage
+
+| Provider | Auth Location | Type |
+|----------|---------------|------|
+| Google (Antigravity) | `~/.local/share/agent-core/auth.json` under `google` key | OAuth |
+| Cerebras | Environment variable | API Key |
+| OpenRouter | Environment variable | API Key |
+
+## Adding New Models
+
+To add custom models to an existing provider, add to the `provider` section in `agent-core.jsonc`:
+
+```jsonc
+"provider": {
+  "provider-id": {
+    "models": {
+      "model-id": {
+        "name": "Display Name",
+        "temperature": true,
+        "reasoning": false,
+        "tool_call": true,
+        "attachment": true,
+        "limit": { "context": 200000, "output": 8192 },
+        "cost": { "input": 0, "output": 0 }
+      }
+    }
+  }
+}
+```