feat: add Ollama Cloud as built-in provider

Add ollama-cloud as a first-class provider with full parity to existing
API-key providers (gemini, zai, minimax, etc.):

- PROVIDER_REGISTRY entry with OLLAMA_API_KEY env var
- Provider aliases: ollama -> custom (local), ollama_cloud -> ollama-cloud
- models.dev integration for accurate context lengths
- URL-to-provider mapping (ollama.com -> ollama-cloud)
- Passthrough model normalization (preserves Ollama model:tag format)
- Default auxiliary model (nemotron-3-nano:30b)
- HermesOverlay in providers.py
- CLI --provider choices, CANONICAL_PROVIDERS entry
- Dynamic model discovery with disk caching (1hr TTL)
- 37 provider-specific tests

Cherry-picked from PR #6038 by kshitijk4poor. Closes #3926

agent/auxiliary_client.py

@@ -104,6 +104,7 @@ _API_KEY_PROVIDER_AUX_MODELS: Dict[str, str] = {
     "opencode-zen": "gemini-3-flash",
     "opencode-go": "glm-5",
     "kilocode": "google/gemini-3-flash-preview",
+    "ollama-cloud": "nemotron-3-nano:30b",
 }
 
 # Vision-specific model overrides for direct providers.

agent/model_metadata.py

@@ -23,7 +23,7 @@ logger = logging.getLogger(__name__)
 # are preserved so the full model name reaches cache lookups and server queries.
 _PROVIDER_PREFIXES: frozenset[str] = frozenset({
     "openrouter", "nous", "openai-codex", "copilot", "copilot-acp",
-    "gemini", "zai", "kimi-coding", "kimi-coding-cn", "minimax", "minimax-cn", "anthropic", "deepseek",
+    "gemini", "ollama-cloud", "zai", "kimi-coding", "kimi-coding-cn", "minimax", "minimax-cn", "anthropic", "deepseek",
     "opencode-zen", "opencode-go", "ai-gateway", "kilocode", "alibaba",
     "qwen-oauth",
     "xiaomi",
@@ -33,6 +33,7 @@ _PROVIDER_PREFIXES: frozenset[str] = frozenset({
     "google", "google-gemini", "google-ai-studio",
     "glm", "z-ai", "z.ai", "zhipu", "github", "github-copilot",
     "github-models", "kimi", "moonshot", "kimi-cn", "moonshot-cn", "claude", "deep-seek",
+    "ollama",
     "opencode", "zen", "go", "vercel", "kilo", "dashscope", "aliyun", "qwen",
     "mimo", "xiaomi-mimo",
     "arcee-ai", "arceeai",
@@ -239,6 +240,7 @@ _URL_TO_PROVIDER: Dict[str, str] = {
     "api.x.ai": "xai",
     "api.xiaomimimo.com": "xiaomi",
     "xiaomimimo.com": "xiaomi",
+    "ollama.com": "ollama-cloud",
 }
 
 

agent/models_dev.py

@@ -169,6 +169,7 @@ PROVIDER_TO_MODELS_DEV: Dict[str, str] = {
     "togetherai": "togetherai",
     "perplexity": "perplexity",
     "cohere": "cohere",
+    "ollama-cloud": "ollama-cloud",
 }
 
 # Reverse mapping: models.dev → Hermes (built lazily)