feat: support ANTHROPIC_BASE_URL, ANTHROPIC_AUTH_TOKEN, and SPACEBOT_MODEL env vars

Add environment variable support for custom Anthropic API endpoints
and authentication tokens, enabling use with API proxies (LiteLLM,
Azure AI Gateway, corporate proxies).

New environment variables:
- ANTHROPIC_BASE_URL: override the Anthropic API endpoint
- ANTHROPIC_AUTH_TOKEN: alternative to ANTHROPIC_API_KEY for proxy auth
- SPACEBOT_MODEL: override all process types with a single model

Also fixes a bug where build_anthropic_request() hardcoded the API URL
instead of using the provider's configured base_url, making custom
base URLs via TOML config ineffective.

Closes #132

Author: adryserage

src/config.rs

@@ -1803,7 +1803,9 @@ impl Config {
     /// Load from environment variables only (no config file).
     pub fn load_from_env(instance_dir: &Path) -> Result<Self> {
         let mut llm = LlmConfig {
-            anthropic_key: std::env::var("ANTHROPIC_API_KEY").ok(),
+            anthropic_key: std::env::var("ANTHROPIC_API_KEY")
+                .ok()
+                .or_else(|| std::env::var("ANTHROPIC_AUTH_TOKEN").ok()),
             openai_key: std::env::var("OPENAI_API_KEY").ok(),
             openrouter_key: std::env::var("OPENROUTER_API_KEY").ok(),
             zhipu_key: std::env::var("ZHIPU_API_KEY").ok(),
@@ -1826,11 +1828,13 @@ impl Config {
 
         // Populate providers from env vars (same as from_toml does)
         if let Some(anthropic_key) = llm.anthropic_key.clone() {
+            let base_url = std::env::var("ANTHROPIC_BASE_URL")
+                .unwrap_or_else(|_| ANTHROPIC_PROVIDER_BASE_URL.to_string());
             llm.providers
                 .entry("anthropic".to_string())
                 .or_insert_with(|| ProviderConfig {
                     api_type: ApiType::Anthropic,
-                    base_url: ANTHROPIC_PROVIDER_BASE_URL.to_string(),
+                    base_url,
                     api_key: anthropic_key,
                     name: None,
                 });
@@ -1938,8 +1942,16 @@ impl Config {
         // Note: We allow boot without provider keys now. System starts in setup mode.
         // Agents are initialized later when keys are added via API.
 
-        // Env-only routing: check for env overrides on channel/worker models
+        // Env-only routing: check for env overrides on channel/worker models.
+        // SPACEBOT_MODEL overrides all process types at once; specific vars take precedence.
         let mut routing = RoutingConfig::default();
+        if let Ok(model) = std::env::var("SPACEBOT_MODEL") {
+            routing.channel = model.clone();
+            routing.branch = model.clone();
+            routing.worker = model.clone();
+            routing.compactor = model.clone();
+            routing.cortex = model;
+        }
         if let Ok(channel_model) = std::env::var("SPACEBOT_CHANNEL_MODEL") {
             routing.channel = channel_model;
         }
@@ -2039,7 +2051,8 @@ impl Config {
                 .anthropic_key
                 .as_deref()
                 .and_then(resolve_env_value)
-                .or_else(|| std::env::var("ANTHROPIC_API_KEY").ok()),
+                .or_else(|| std::env::var("ANTHROPIC_API_KEY").ok())
+                .or_else(|| std::env::var("ANTHROPIC_AUTH_TOKEN").ok()),
             openai_key: toml
                 .llm
                 .openai_key
@@ -2162,11 +2175,13 @@ impl Config {
         };
 
         if let Some(anthropic_key) = llm.anthropic_key.clone() {
+            let base_url = std::env::var("ANTHROPIC_BASE_URL")
+                .unwrap_or_else(|_| ANTHROPIC_PROVIDER_BASE_URL.to_string());
             llm.providers
                 .entry("anthropic".to_string())
                 .or_insert_with(|| ProviderConfig {
                     api_type: ApiType::Anthropic,
-                    base_url: ANTHROPIC_PROVIDER_BASE_URL.to_string(),
+                    base_url,
                     api_key: anthropic_key,
                     name: None,
                 });

src/llm/anthropic/params.rs

@@ -7,7 +7,6 @@ use super::tools;
 use reqwest::RequestBuilder;
 use rig::completion::CompletionRequest;
 
-const ANTHROPIC_API_URL: &str = "https://api.anthropic.com/v1/messages";
 const CLAUDE_CODE_SYSTEM_PREAMBLE: &str =
     "You are Claude Code, Anthropic's official CLI for Claude.";
 
@@ -32,21 +31,39 @@ fn is_opus(model_id: &str) -> bool {
     model_id.contains("opus")
 }
 
+/// Construct the full messages endpoint URL from a base URL.
+///
+/// If the base URL already ends with a path segment (e.g. `/v1/messages`),
+/// use it as-is. Otherwise append `/v1/messages`.
+fn messages_url(base_url: &str) -> String {
+    let trimmed = base_url.trim_end_matches('/');
+    if trimmed.ends_with("/v1/messages") {
+        trimmed.to_string()
+    } else {
+        format!("{trimmed}/v1/messages")
+    }
+}
+
 /// Build a fully configured Anthropic API request from a CompletionRequest.
 ///
+/// `base_url` is the provider's configured base URL (e.g. `https://api.anthropic.com`
+/// or a custom proxy). The `/v1/messages` path is appended automatically.
+///
 /// `thinking_effort` controls adaptive thinking: "auto" picks max for Opus /
 /// high for others, or pass "max", "high", "medium", "low" explicitly.
 pub fn build_anthropic_request(
     http_client: &reqwest::Client,
     api_key: &str,
+    base_url: &str,
     model_name: &str,
     request: &CompletionRequest,
     thinking_effort: &str,
 ) -> AnthropicRequest {
     let is_oauth = auth::detect_auth_path(api_key) == AnthropicAuthPath::OAuthToken;
     let adaptive_thinking = supports_adaptive_thinking(model_name);
     let retention = cache::resolve_cache_retention(None);
-    let cache_control = cache::get_cache_control(ANTHROPIC_API_URL, retention);
+    let url = messages_url(base_url);
+    let cache_control = cache::get_cache_control(&url, retention);
 
     let mut body = serde_json::json!({
         "model": model_name,
@@ -80,7 +97,7 @@ pub fn build_anthropic_request(
     }
 
     let builder = http_client
-        .post(ANTHROPIC_API_URL)
+        .post(&url)
         .header("anthropic-version", "2023-06-01")
         .header("content-type", "application/json");
 

src/llm/model.rs

@@ -352,6 +352,7 @@ impl SpacebotModel {
         let anthropic_request = crate::llm::anthropic::build_anthropic_request(
             self.llm_manager.http_client(),
             api_key,
+            &provider_config.base_url,
             &self.model_name,
             &request,
             effort,