feat: error handling, retry with backoff, and circuit breaker

Add robust error handling to the evolution loop and LLM adapters:
- Retry utility with exponential backoff for transient errors (429, 5xx, timeouts)
- Per-call error isolation in evaluator and judge adapter
- Circuit breaker in EvolutionLoop (trips after N consecutive failures)
- CLI flags: --max-retries, --error-strategy (skip|retry|abort)
- Config fields: max_retries, retry_delay_base, circuit_breaker_threshold, error_strategy
- 16 new unit tests covering all error handling paths

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/prometheus/cli/app.py

@@ -56,6 +56,16 @@ def optimize(
         "--verbose",
         help="Print detailed progress.",
     ),
+    max_retries: int = typer.Option(
+        3,
+        "--max-retries",
+        help="Max retry attempts for transient LLM errors (429, timeout, 5xx).",
+    ),
+    error_strategy: str = typer.Option(
+        "retry",
+        "--error-strategy",
+        help="How to handle errors: skip | retry | abort.",
+    ),
 ) -> None:
     """Optimize a prompt without any reference data.
 
@@ -115,6 +125,10 @@ def optimize(
         n_synthetic_inputs=raw_config.get("n_synthetic_inputs", 20),
         minibatch_size=raw_config.get("minibatch_size", 5),
         seed=raw_config.get("seed", 42),
+        max_retries=raw_config.get("max_retries", max_retries),
+        retry_delay_base=raw_config.get("retry_delay_base", 1.0),
+        circuit_breaker_threshold=raw_config.get("circuit_breaker_threshold", 5),
+        error_strategy=raw_config.get("error_strategy", error_strategy),
         output_path=output,
         verbose=verbose,
     )
@@ -139,11 +153,23 @@ def optimize(
         **_model_lm_kwargs(config.synth_api_base, config.synth_api_key_env, global_api_base, global_api_key_env),
     )
 
-    # 3. Build adapters (Dependency Injection — each gets its own LM)
+    # 3. Build adapters (Dependency Injection — each gets its own LM + retry config)
     synth_adapter = DSPySyntheticAdapter(lm=synth_lm)
-    llm_adapter = DSPyLLMAdapter(lm=task_lm)
-    judge_adapter = DSPyJudgeAdapter(lm=judge_lm)
-    proposer_adapter = DSPyProposerAdapter(lm=proposer_lm)
+    llm_adapter = DSPyLLMAdapter(
+        lm=task_lm,
+        max_retries=config.max_retries,
+        retry_delay_base=config.retry_delay_base,
+    )
+    judge_adapter = DSPyJudgeAdapter(
+        lm=judge_lm,
+        max_retries=config.max_retries,
+        retry_delay_base=config.retry_delay_base,
+    )
+    proposer_adapter = DSPyProposerAdapter(
+        lm=proposer_lm,
+        max_retries=config.max_retries,
+        retry_delay_base=config.retry_delay_base,
+    )
     bootstrap = SyntheticBootstrap(generator=synth_adapter, seed=config.seed)
     evaluator = PromptEvaluator(executor=llm_adapter, judge=judge_adapter)
     use_case = OptimizePromptUseCase(