fix: add provider warmup to prevent cold-start timeout on first channel message

The first API request after daemon startup consistently timed out (120s)
when using channels (Telegram, Discord, etc.), requiring a retry before
succeeding. This happened because the reqwest HTTP client's connection
pool was cold — no TLS handshake, DNS resolution, or HTTP/2 negotiation
had occurred yet.

The fix adds a `warmup()` method to the Provider trait that establishes
the connection pool on startup by hitting a lightweight endpoint
(`/api/v1/auth/key` for OpenRouter). The channel server calls this
immediately after creating the provider, before entering the message
processing loop.

Tested on Raspberry Pi 5 (aarch64) with OpenRouter + DeepSeek v3.2 via
Telegram channel. Before: first message took 2-7 minutes (120s timeout +
retries). After: first message responds in <30s with no retries.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/channels/mod.rs

@@ -426,6 +426,13 @@ pub async fn start_channels(config: Config) -> Result<()> {
         config.api_key.as_deref(),
         &config.reliability,
     )?);
+
+    // Warm up the provider connection pool (TLS handshake, DNS, HTTP/2 setup)
+    // so the first real message doesn't hit a cold-start timeout.
+    if let Err(e) = provider.warmup().await {
+        tracing::warn!("Provider warmup failed (non-fatal): {e}");
+    }
+
     let model = config
         .default_model
         .clone()

src/providers/openrouter.rs

@@ -51,6 +51,22 @@ impl OpenRouterProvider {
 
 #[async_trait]
 impl Provider for OpenRouterProvider {
+    async fn warmup(&self) -> anyhow::Result<()> {
+        // Hit a lightweight endpoint to establish TLS + HTTP/2 connection pool.
+        // This prevents the first real chat request from timing out on cold start.
+        let api_key = self
+            .api_key
+            .as_ref()
+            .ok_or_else(|| anyhow::anyhow!("No API key for warmup"))?;
+        let _ = self
+            .client
+            .get("https://openrouter.ai/api/v1/auth/key")
+            .header("Authorization", format!("Bearer {api_key}"))
+            .send()
+            .await;
+        Ok(())
+    }
+
     async fn chat_with_system(
         &self,
         system_prompt: Option<&str>,

src/providers/reliable.rs

@@ -25,6 +25,14 @@ impl ReliableProvider {
 
 #[async_trait]
 impl Provider for ReliableProvider {
+    async fn warmup(&self) -> anyhow::Result<()> {
+        if let Some((name, provider)) = self.providers.first() {
+            tracing::info!(provider = name, "Warming up provider connection pool");
+            provider.warmup().await?;
+        }
+        Ok(())
+    }
+
     async fn chat_with_system(
         &self,
         system_prompt: Option<&str>,

src/providers/traits.rs

@@ -14,4 +14,10 @@ pub trait Provider: Send + Sync {
         model: &str,
         temperature: f64,
     ) -> anyhow::Result<String>;
+
+    /// Warm up the HTTP connection pool (TLS handshake, DNS, HTTP/2 setup).
+    /// Default implementation is a no-op; providers with HTTP clients should override.
+    async fn warmup(&self) -> anyhow::Result<()> {
+        Ok(())
+    }
 }