huskies: merge 646_bug_watchdog_from_bug_624_is_not_actually_enforcing_max_turns_max_budget_usd_in_production

server/src/agents/mod.rs

@@ -3,7 +3,7 @@ pub mod gates;
 pub mod lifecycle;
 pub mod local_prompt;
 pub mod merge;
-mod pool;
+pub(crate) mod pool;
 pub(crate) mod pty;
 pub mod runtime;
 pub mod token_usage;
@@ -161,6 +161,27 @@ pub struct TokenUsage {
 }
 
 impl TokenUsage {
+    /// Estimate USD cost from token counts using approximate per-model pricing.
+    ///
+    /// Used by the watchdog to compute in-flight budget from per-message usage
+    /// data in the agent log (since `total_cost_usd` is only available in the
+    /// `result` event at session end).  Uses conservative (high) pricing when
+    /// the model is unknown so budget limits are hit sooner rather than later.
+    pub fn estimate_cost_usd(&self, model: Option<&str>) -> f64 {
+        // Per-million-token pricing (input, output, cache_read, cache_create).
+        let (inp, out, cr, cc) = match model {
+            Some(m) if m.contains("haiku") => (0.80, 4.0, 0.08, 1.00),
+            Some(m) if m.contains("sonnet") => (3.0, 15.0, 0.30, 3.75),
+            // Opus or unknown → most expensive = conservative.
+            _ => (15.0, 75.0, 1.50, 18.75),
+        };
+        (self.input_tokens as f64 * inp
+            + self.output_tokens as f64 * out
+            + self.cache_read_input_tokens as f64 * cr
+            + self.cache_creation_input_tokens as f64 * cc)
+            / 1_000_000.0
+    }
+
     /// Parse token usage from a Claude Code `result` JSON event.
     pub fn from_result_event(json: &serde_json::Value) -> Option<Self> {
         let usage = json.get("usage")?;