feat: add native Ollama provider support via OLLAMA_HOST env var

- OLLAMA_HOST takes priority over OPENAI_BASE_URL for local Ollama instances
- No API key required; placeholder token used for Authorization header
- Model names like 'qwen3:8b' bypass strict provider/model syntax validation
- detect_provider_kind() checks OLLAMA_HOST first in routing cascade
- ProviderClient dispatch uses from_ollama_env() when OLLAMA_HOST is set
- Updated USAGE.md and docs with OLLAMA_HOST as preferred env var
- Added OLLAMA_CONFIG constant and from_ollama_env() to openai_compat
- Added test_ollama_host_bypasses_model_validation unit test
- Supersedes PR #3213 (which had a duplicate if-let bug in mod.rs)

Author: bellman

USAGE.md

@@ -245,6 +245,7 @@ export ANTHROPIC_AUTH_TOKEN="anthropic-oauth-or-proxy-bearer-token"
 | `sk-ant-*` API key | `ANTHROPIC_API_KEY` | `x-api-key: sk-ant-...` | [console.anthropic.com](https://console.anthropic.com) |
 | OAuth access token (opaque) | `ANTHROPIC_AUTH_TOKEN` | `Authorization: Bearer ...` | an Anthropic-compatible proxy or OAuth flow that mints bearer tokens |
 | OpenRouter key (`sk-or-v1-*`) | `OPENAI_API_KEY` + `OPENAI_BASE_URL=https://openrouter.ai/api/v1` | `Authorization: Bearer ...` | [openrouter.ai/keys](https://openrouter.ai/keys) |
+| Ollama local instance | `OLLAMA_HOST` | no auth header (Ollama requires none) | local Ollama server at `http://127.0.0.1:11434` |
 
 **Why this matters:** if you paste an `sk-ant-*` key into `ANTHROPIC_AUTH_TOKEN`, Anthropic's API will return `401 Invalid bearer token` because `sk-ant-*` keys are rejected over the Bearer header. The fix is a one-line env var swap — move the key to `ANTHROPIC_API_KEY`. Recent `claw` builds detect this exact shape (401 + `sk-ant-*` in the Bearer slot) and append a hint to the error message pointing at the fix.
 
@@ -305,18 +306,18 @@ cd rust
 ### Ollama
 
 ```bash
-export OPENAI_BASE_URL="http://127.0.0.1:11434/v1"
-unset OPENAI_API_KEY
+export OLLAMA_HOST="http://127.0.0.1:11434"
 
 cd rust
 ./target/debug/claw --model "llama3.2" prompt "summarize this repository in one sentence"
 ```
 
-For Ollama tags with punctuation (for example `qwen2.5-coder:7b`), `OPENAI_BASE_URL` selects the local OpenAI-compatible route even when `OPENAI_API_KEY` is unset:
+`OLLAMA_HOST` is the preferred env var. Claw routes all models to the local Ollama endpoint automatically, and no API key is needed. The older `OPENAI_BASE_URL` + `OPENAI_API_KEY` workaround is also supported.
+
+For Ollama tags with punctuation (for example `qwen2.5-coder:7b`), both approaches work:
 
 ```bash
-export OPENAI_BASE_URL="http://127.0.0.1:11434/v1"
-unset OPENAI_API_KEY
+export OLLAMA_HOST="http://127.0.0.1:11434"
 
 cd rust
 ./target/debug/claw --model "qwen2.5-coder:7b" prompt "reply with ready"

docs/local-openai-compatible-providers.md

@@ -57,11 +57,12 @@ ollama serve
 In another shell:
 
 ```bash
-export OPENAI_BASE_URL="http://127.0.0.1:11434/v1"
-unset OPENAI_API_KEY
+export OLLAMA_HOST="http://127.0.0.1:11434"
 claw --model "qwen3:latest" prompt "Reply exactly HELLO_WORLD_123"
 ```
 
+`OLLAMA_HOST` is the preferred env var for Ollama. Claw routes all models to the local OpenAI-compatible endpoint automatically when this is set, and no API key is needed. The older `OPENAI_BASE_URL` + `OPENAI_API_KEY` workaround is also supported for existing setups.
+
 If Ollama is running without auth, `unset OPENAI_API_KEY` is acceptable. Use a placeholder token rather than a real cloud API key if your local server requires an Authorization header.
 
 ## llama.cpp server

rust/crates/api/src/client.rs

@@ -32,16 +32,25 @@ impl ProviderClient {
                 OpenAiCompatConfig::xai(),
             )?)),
             ProviderKind::OpenAi => {
-                // DashScope models (qwen-*) also return ProviderKind::OpenAi because they
-                // speak the OpenAI wire format, but they need the DashScope config which
-                // reads DASHSCOPE_API_KEY and points at dashscope.aliyuncs.com.
-                let config = match providers::metadata_for_model(&resolved_model) {
-                    Some(meta) if meta.auth_env == "DASHSCOPE_API_KEY" => {
-                        OpenAiCompatConfig::dashscope()
-                    }
-                    _ => OpenAiCompatConfig::openai(),
-                };
-                Ok(Self::OpenAi(OpenAiCompatClient::from_env(config)?))
+                // OLLAMA_HOST takes priority: local Ollama needs no API key
+                // and ignores DashScope/OpenAI env-based dispatch.
+                if std::env::var_os("OLLAMA_HOST").is_some() {
+                    Ok(Self::OpenAi(
+                        openai_compat::OpenAiCompatClient::from_ollama_env()
+                            .expect("from_ollama_env always returns Some"),
+                    ))
+                } else {
+                    // DashScope models (qwen-*) also return ProviderKind::OpenAi because they
+                    // speak the OpenAI wire format, but they need the DashScope config which
+                    // reads DASHSCOPE_API_KEY and points at dashscope.aliyuncs.com.
+                    let config = match providers::metadata_for_model(&resolved_model) {
+                        Some(meta) if meta.auth_env == "DASHSCOPE_API_KEY" => {
+                            OpenAiCompatConfig::dashscope()
+                        }
+                        _ => OpenAiCompatConfig::openai(),
+                    };
+                    Ok(Self::OpenAi(OpenAiCompatClient::from_env(config)?))
+                }
             }
         }
     }

rust/crates/api/src/providers/mod.rs

@@ -351,6 +351,11 @@ fn looks_like_local_openai_model(model: &str) -> bool {
 
 #[must_use]
 pub fn detect_provider_kind(model: &str) -> ProviderKind {
+    // OLLAMA_HOST takes priority: if set, route all models through the local
+    // OpenAI-compatible endpoint regardless of model name or other env vars.
+    if std::env::var_os("OLLAMA_HOST").is_some() {
+        return ProviderKind::OpenAi;
+    }
     let resolved_model = resolve_model_alias(model);
     if let Some(metadata) = metadata_for_model(&resolved_model) {
         return metadata.provider;

rust/crates/api/src/providers/openai_compat.rs

@@ -49,6 +49,14 @@ const XAI_MAX_REQUEST_BODY_BYTES: usize = 52_428_800; // 50MB
 const OPENAI_MAX_REQUEST_BODY_BYTES: usize = 104_857_600; // 100MB
 const DASHSCOPE_MAX_REQUEST_BODY_BYTES: usize = 6_291_456; // 6MB (observed limit in dogfood)
 
+pub const OLLAMA_CONFIG: OpenAiCompatConfig = OpenAiCompatConfig {
+    provider_name: "Ollama",
+    api_key_env: "OLLAMA_HOST",
+    base_url_env: "OLLAMA_HOST",
+    default_base_url: "http://127.0.0.1:11434/v1",
+    max_request_body_bytes: 104_857_600,
+};
+
 impl OpenAiCompatConfig {
     #[must_use]
     pub const fn xai() -> Self {
@@ -149,6 +157,22 @@ impl OpenAiCompatClient {
         };
         Ok(Self::new(api_key, config).with_base_url(base_url))
     }
+    /// Create an Ollama client from `OLLAMA_HOST` env var.
+    /// Ollama requires no API key; a placeholder is used for the Authorization header.
+    pub fn from_ollama_env() -> Option<Self> {
+        let host =
+            std::env::var("OLLAMA_HOST").unwrap_or_else(|_| "http://127.0.0.1:11434".to_string());
+        let base_url = format!("{}/v1", host.trim_end_matches('/'));
+        Some(Self {
+            http: build_http_client_or_default(),
+            api_key: "ollama".to_string(),
+            config: OLLAMA_CONFIG,
+            base_url,
+            max_retries: DEFAULT_MAX_RETRIES,
+            initial_backoff: DEFAULT_INITIAL_BACKOFF,
+            max_backoff: DEFAULT_MAX_BACKOFF,
+        })
+    }
 
     #[must_use]
     pub fn with_base_url(mut self, base_url: impl Into<String>) -> Self {

rust/crates/rusty-claude-cli/src/main.rs

@@ -2903,6 +2903,14 @@ fn resolve_model_alias_with_config(model: &str) -> String {
 /// Rejects: empty, whitespace-only, strings with spaces, or invalid chars.
 fn validate_model_syntax(model: &str) -> Result<(), String> {
     let trimmed = model.trim();
+    // Ollama models use names like "qwen3:8b" that don't match provider/model
+    // syntax. Skip strict validation when OLLAMA_HOST is configured.
+    if std::env::var_os("OLLAMA_HOST").is_some() {
+        if trimmed.is_empty() {
+            return Err("invalid model syntax: model string cannot be empty.\nUsage: --model <model-name>  e.g. --model qwen3:8b".to_string());
+        }
+        return Ok(());
+    }
     if trimmed.is_empty() {
         return Err("invalid model syntax: model string cannot be empty.\nUsage: --model <provider/model>  e.g. --model anthropic/claude-opus-4-7".to_string());
     }
@@ -19689,4 +19697,16 @@ mod alias_resolution_tests {
         assert_eq!(resolve_model_alias_with_config(model), model);
         assert!(validate_model_syntax(model).is_ok());
     }
+    #[test]
+    fn test_ollama_host_bypasses_model_validation() {
+        // Safety: test sets and clears env var within the test.
+        std::env::set_var("OLLAMA_HOST", "http://127.0.0.1:11434");
+        // Ollama model names with colons pass
+        assert!(validate_model_syntax("qwen3:8b").is_ok());
+        assert!(validate_model_syntax("gemma4:e2b").is_ok());
+        assert!(validate_model_syntax("qwen3.6:27b-nvfp4").is_ok());
+        // Empty model still rejected
+        assert!(validate_model_syntax("").is_err());
+        std::env::remove_var("OLLAMA_HOST");
+    }
 }