Avoid unnecessary model reviews and speculative type repairs

src/re_agent/agents/loop.py

@@ -25,6 +25,7 @@
 from re_agent.llm.observed import CallBudget, ObservedProvider
 from re_agent.llm.protocol import LLMProvider
 from re_agent.parity.source_indexer import SourceIndexer
+from re_agent.verification.candidate import extract_candidate_body
 from re_agent.verification.objective import verify_candidate
 
 
@@ -128,8 +129,25 @@ def run_fix_loop(
             log_path = log_dir / f"round{round_num}-{timestamp}-reverser.json"
             log_path.write_text(json.dumps(log_entry, indent=2), encoding="utf-8")
 
-        # Check
-        verdict = checker.check(code, target)
+        # Avoid spending a reviewer call on output the configured candidate gate
+        # cannot consume. Keep the same repair/checkpoint path as other failures.
+        preflight_error = None
+        if candidate_gate is not None:
+            try:
+                extract_candidate_body(code)
+            except ValueError as exc:
+                preflight_error = str(exc)
+        if preflight_error:
+            checker.last_prompt = ""
+            checker.last_response = ""
+            verdict = CheckerVerdict(
+                verdict=Verdict.FAIL,
+                summary="Local candidate preflight failed; model review skipped",
+                issues=[preflight_error],
+                fix_instructions=["Return exactly one complete function definition without helper definitions."],
+            )
+        else:
+            verdict = checker.check(code, target)
         last_verdict = verdict
 
         objective_verdict: ObjectiveVerdict | None = None
@@ -148,6 +166,7 @@ def run_fix_loop(
                 "round": round_num,
                 "timestamp": timestamp,
                 "phase": "check",
+                "checker_skipped": preflight_error is not None,
                 "prompt": checker.last_prompt,
                 "response": checker.last_response,
                 "verdict": verdict.verdict.value,

src/re_agent/agents/prompts/checker_system.md

@@ -2,7 +2,7 @@ You are a reverse engineering quality checker. Your job is to verify that revers
 
 Verification standards:
 - Every line of Ghidra logic must have corresponding source code
-- Every struct offset must map to a named member
+- Use supplied type evidence to verify named members. When no layout is available, accept explicit byte offsets that preserve access widths and semantics; do not fail code solely for lacking member names or demand invented structs.
 - Every function call must be identified and matched
 - Expression order must match exactly (floating point is order-sensitive)
 - No missing branches, conditions, or edge cases

src/re_agent/agents/prompts/reverser_task.md

@@ -24,8 +24,8 @@ ${project_rules}
 
 Requirements:
 1. Match every branch and call from the decompile
-2. Map all offsets (e.g. param_1 + 0x88) to real member names
+2. Use member names only when supported by supplied type evidence. Otherwise preserve the exact byte offset and access width, and document the unresolved layout; do not invent structs or member names.
 3. Preserve exact expression/operand order
 4. Use existing project patterns and naming conventions
-5. Output the complete function implementation in a ```cpp block
+5. Output exactly one complete function implementation in a ```cpp block. Do not wrap it in namespace/class definitions or add helper type/function definitions; report missing declarations outside the code block.
 6. End with: REVERSED_FUNCTION: ${class_name}::${function_name} (${address})

tests/test_agents/test_preflight.py

@@ -0,0 +1,39 @@
+"""Reject unusable candidate shapes before spending reviewer calls."""
+import json
+
+import pytest
+
+from re_agent.agents.loop import run_fix_loop
+from re_agent.backend.stub import StubBackend
+from re_agent.core.models import FunctionTarget
+from tests.test_agents.test_loop import MockLLM
+
+
+@pytest.mark.parametrize("invalid", [
+    "struct Layout { int field; }; int f(Layout* p) { return p->field; }",
+    "int f() { return 0;",
+    "int f() { return 0; } int g() { return 1; }",
+])
+def test_invalid_candidate_skips_reviewer_then_repairs_within_budget(tmp_path, invalid):
+    reverser = MockLLM([f"```cpp\n{invalid}\n```", "```cpp\nint f() { return 0; }\n```"])
+    checker = MockLLM(['{"verdict":"PASS","summary":"Matches","issues":[],"fix_instructions":[]}'])
+    result = run_fix_loop(FunctionTarget("100", "", "f"), StubBackend(), reverser, checker,
+                          candidate_gate=lambda result: result, objective_verifier_enabled=False,
+                          max_rounds=2, max_llm_calls=3, log_dir=tmp_path)
+    assert result.success
+    assert result.rounds_used == 2
+    assert reverser._idx == 2
+    assert checker._idx == 1
+    log = next(tmp_path.glob("*/round1-*-checker.json"))
+    assert json.loads(log.read_text())["checker_skipped"] is True
+
+
+def test_repeated_invalid_candidates_never_call_reviewer(tmp_path):
+    reverser = MockLLM(["```cpp\nint f() {\n```"])
+    checker = MockLLM(["VERDICT: PASS"])
+    result = run_fix_loop(FunctionTarget("100", "", "f"), StubBackend(), reverser, checker,
+                          candidate_gate=lambda result: result, objective_verifier_enabled=False,
+                          max_rounds=3, log_dir=tmp_path)
+    assert not result.success
+    assert checker._idx == 0
+    assert result.error and "without progress" in result.error

tests/test_agents/test_prompt_contract.py

@@ -0,0 +1,18 @@
+"""Keep reconstruction/review instructions consistent with missing type evidence."""
+from re_agent.agents.checker import PROMPTS_DIR
+from re_agent.utils.templates import render_template
+
+
+def test_missing_layout_does_not_require_invented_members():
+    reverser = render_template(PROMPTS_DIR / "reverser_task.md")
+    checker = render_template(PROMPTS_DIR / "checker_system.md")
+    assert "preserve the exact byte offset and access width" in reverser
+    assert "do not invent structs or member names" in reverser
+    assert "accept explicit byte offsets" in checker
+    assert "do not fail code solely for lacking member names" in checker
+
+
+def test_requested_candidate_matches_single_body_overlay_contract():
+    prompt = render_template(PROMPTS_DIR / "reverser_task.md")
+    assert "exactly one complete function implementation" in prompt
+    assert "report missing declarations outside the code block" in prompt