fix(team): inject /setup-saved provider config for sub-agents

Sub-agents failed because the main CLI calls inject_config_as_env_fallbacks()
to set CLAWCUSTOMOPENAI_API_KEY / CLAWCUSTOMOPENAI_BASE_URL (and other
provider env vars) before building its provider client, but the sub-agent
spawn path in the tools crate never did. Custom providers set up via /setup
were invisible to spawned agents, so they fell through to the Anthropic
provider and died with 'missing Anthropic credentials'.

Move inject_config_as_env_fallbacks from main.rs private fn into
runtime/src/config.rs as a pub fn, export it via runtime::lib.rs, and call
it at the top of run_agent_job() before the agent runtime is built.

- runtime::inject_config_as_env_fallbacks(): idempotent (only sets env vars
  that aren't already present), reads provider config saved by /setup,
  maps provider kind -> env var names (including custom-openai ->
  CLAWCUSTOMOPENAI_*), injects api_key/base_url/model.
- main.rs now calls runtime::inject_config_as_env_fallbacks() instead of
  the local private version.
- tools::run_agent_job calls runtime::inject_config_as_env_fallbacks()
  before building the agent runtime so custom/exotic providers work for
  spawned agents too.

Together with the earlier model-resolution and chain-fallback fixes
(d8716efb), sub-agents now: (1) use the session's model by default,
(2) inject the /setup-saved provider credentials, and (3) fall through
to the next configured chain entry on a model-not-found 404.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

rust/crates/runtime/src/config.rs

@@ -2608,6 +2608,49 @@ fn deep_merge_objects(
     }
 }
 
+/// Read the provider config saved by `/setup` and inject its credentials
+/// into the environment so `ProviderClient::from_model()` can find them via
+/// the env-var-based provider dispatch. Only sets vars that aren't already
+/// present (preserves explicit env). Idempotent.
+///
+/// Called by the main CLI at startup and by sub-agent threads in the tools
+/// crate so that custom/ exotic providers work for spawned agents too.
+pub fn inject_config_as_env_fallbacks() {
+    let cwd = std::env::current_dir().unwrap_or_default();
+    let Ok(config) = ConfigLoader::default_for(&cwd).load() else {
+        return;
+    };
+    let provider = config.provider();
+
+    // Map provider kind to the expected env var names
+    let (api_key_env, base_url_env) = match provider.kind().unwrap_or("anthropic") {
+        "anthropic" => ("ANTHROPIC_API_KEY", "ANTHROPIC_BASE_URL"),
+        "xai" => ("XAI_API_KEY", "XAI_BASE_URL"),
+        "openai" => ("OPENAI_API_KEY", "OPENAI_BASE_URL"),
+        "dashscope" => ("DASHSCOPE_API_KEY", "DASHSCOPE_BASE_URL"),
+        "custom-openai" => ("CLAWCUSTOMOPENAI_API_KEY", "CLAWCUSTOMOPENAI_BASE_URL"),
+        _ => return, // unknown provider kind — don't inject
+    };
+
+    // Only set env vars that aren't already set (preserve user's explicit env)
+    if let Some(api_key) = provider.api_key() {
+        if std::env::var(api_key_env).is_err() {
+            std::env::set_var(api_key_env, api_key);
+        }
+    }
+    if let Some(base_url) = provider.base_url() {
+        if std::env::var(base_url_env).is_err() {
+            std::env::set_var(base_url_env, base_url);
+        }
+    }
+    // Also inject the saved model so resolve_model_alias sees it
+    if let Some(model) = provider.model() {
+        if std::env::var("CLAWD_PROVIDER_MODEL").is_err() {
+            std::env::set_var("CLAWD_PROVIDER_MODEL", model);
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::{

rust/crates/runtime/src/lib.rs

@@ -68,9 +68,9 @@ pub use compact::{
     get_compact_continuation_message, should_compact, CompactionConfig, CompactionResult,
 };
 pub use config::{
-    clear_user_provider_settings, default_config_home, save_user_provider_settings,
-    suppress_config_warnings_for_json_mode, ApiTimeoutConfig, ConfigEntry, ConfigError,
-    ConfigFileReport, ConfigFileStatus, ConfigInspection, ConfigLoader, ConfigSource,
+    clear_user_provider_settings, default_config_home, inject_config_as_env_fallbacks,
+    save_user_provider_settings, suppress_config_warnings_for_json_mode, ApiTimeoutConfig, ConfigEntry,
+    ConfigError, ConfigFileReport, ConfigFileStatus, ConfigInspection, ConfigLoader, ConfigSource,
     McpConfigCollection, McpInvalidServerConfig, McpManagedProxyServerConfig, McpOAuthConfig,
     McpRemoteServerConfig, McpSdkServerConfig, McpServerConfig, McpStdioServerConfig, McpTransport,
     McpWebSocketServerConfig, OAuthConfig, ProviderFallbackConfig, ResolvedPermissionMode,

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

@@ -1018,7 +1018,7 @@ fn run() -> Result<(), Box<dyn std::error::Error>> {
     // vars are preserved — resolution order remains: env var > .env file >
     // stored config. This only runs in the real binary (run() is not called by
     // unit tests) to avoid leaking user config into the test suite.
-    inject_config_as_env_fallbacks();
+    runtime::inject_config_as_env_fallbacks();
     match parse_args(&args)? {
         CliAction::DumpManifests {
             output_format,

rust/crates/tools/src/lib.rs

@@ -5523,6 +5523,13 @@ fn teardown_agent_worktree(agent_id: &str, worktree_path: &std::path::Path) -> R
 }
 
 fn run_agent_job(job: &AgentJob) -> Result<(), String> {
+    // Inject provider credentials from /setup-saved config into env vars so
+    // sub-agents can reach the same endpoint the user connected the main session
+    // with (e.g. custom-openai's CLAWCUSTOMOPENAI_API_KEY / BASE_URL). Without
+    // this, sub-agents can't find custom/ or exotic providers that were set up
+    // via /setup rather than via explicit env vars.
+    runtime::inject_config_as_env_fallbacks();
+
     // Claim task if task_id is set (prevents duplicate work)
     if let Some(ref task_id) = job.task_id {
         if let Some(ref team_id) = job.team_id {