Record rate-limit waits in benchmark runs, and leave them out of time

The client waits RATE_LIMIT_RETRY_S and retries once on a 429, silently.
A benchmark run that waited looked slower than the model is: on
2026-09-27, fast models under the unit-test key's 200k tokens/minute
limit had 20-45 s runs that were probably waits.

Both clients now report last_rate_limit_wait_s after every call, even
one that then fails. The benchmark sums it per run into
rate_limit_wait_s, the report's time column leaves it out, and a new
429 column counts the runs that waited. Results stored before this
load unchanged.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

nisse-dev/src/nisse_dev/bench/runner.py

@@ -40,6 +40,7 @@ class MeteringClient:
         self.tokens_out = 0
         self.cost = 0.0
         self.fallbacks: list[str] = []
+        self.rate_limit_wait_s = 0.0
 
     def complete(
         self,
@@ -49,7 +50,14 @@ class MeteringClient:
         system: str | None = None,
     ) -> list[CanonicalEvent]:
         self.calls += 1
-        produced = self._inner.complete(events, tools, model, system=system)
+        try:
+            produced = self._inner.complete(events, tools, model, system=system)
+        finally:
+            # Counted even when the call fails: a rate limit that never
+            # cleared still cost the run its wait.
+            self.rate_limit_wait_s += float(
+                getattr(self._inner, "last_rate_limit_wait_s", 0.0) or 0.0
+            )
         usage = getattr(self._inner, "last_usage", {}) or {}
         self.tokens_in += int(usage.get("input", 0))
         self.tokens_out += int(usage.get("output", 0))
@@ -90,6 +98,8 @@ class RunRecord:
     cost: float
     wall_s: float
     fallbacks: list[str] = field(default_factory=list)
+    # Part of wall_s spent waiting out the proxy's rate limit, not working.
+    rate_limit_wait_s: float = 0.0
     check_output: str = ""
 
     def to_json(self) -> dict[str, Any]:
@@ -214,5 +224,6 @@ def run_task(
         cost=round(meter.cost, 6),
         wall_s=round(wall, 1),
         fallbacks=meter.fallbacks,
+        rate_limit_wait_s=meter.rate_limit_wait_s,
         check_output=check_output,
     )