search budget: recalibrated caps after the first measured searches [skip ci]

Settled ~$0.003 per model call; worst-case reservations exhausted the $0.05 task
allowance after 2-4 calls. Now $0.40 per task, $2 per search (maintainer decision).

Co-Authored-By: Claude Fable 5.1 <[email protected]>

src/openultrasast/search/budget.py

@@ -6,8 +6,10 @@ from dataclasses import dataclass
 
 @dataclass(frozen=True)
 class SearchBudget:
-    spend_usd: float = 0.50
-    max_call_usd: float = 0.05
+    # Recalibrated 2026-10-05 on the first three measured searches: settled cost was ~$0.003 per model call,
+    # but worst-case reservations (~$0.027 per call) exhausted the old $0.05 task allowance after 2-4 calls.
+    spend_usd: float = 2.00
+    max_call_usd: float = 0.40
     reason_rounds: int = 4
     intents_per_round: int = 3
     demonstrations: int = 3

tests/test_search_coordinator.py

@@ -71,7 +71,7 @@ def test_claim_checkpoint_survives_interrupt_without_free_spend(tmp_path):
     checkpoint = b.head
     resumed = Board.resume(b.store, "search-1", checkpoint, coordinator="host")
     state = Coordinator(resumed, lambda task: {"status": "ok", "cost_usd": 0, "intents": []}).run()
-    assert state["checkpoint"]["spent_usd"] == 0.05
+    assert state["checkpoint"]["spent_usd"] == SearchBudget().max_call_usd
     assert state["checkpoint"]["tasks"] == 3
 
 
@@ -98,7 +98,7 @@ def test_cleanup_failure_halts_and_charges_unknown_spend(tmp_path):
     with pytest.raises(RuntimeError, match="cleanup"):
         Coordinator(b, broken).run()
     assert len(calls) == 1
-    assert b.state["checkpoint"]["spent_usd"] == 0.05
+    assert b.state["checkpoint"]["spent_usd"] == SearchBudget().max_call_usd
     assert b.state["checkpoint"]["pending"]["id"] == calls[0].id