diff --git a/cross_eval/agent.py b/cross_eval/agent.py
index 0af5949..b52acf8 100644
--- a/cross_eval/agent.py
+++ b/cross_eval/agent.py
@@ -32,20 +32,33 @@ _NO_CHANGE_ACK_MARKERS = (
 _CHANGE_CLAIM_MARKERS = (
     "summary of all changes made",
     "here's a summary of all changes made",
+    "here is a summary of all changes",
     "implemented",
     "i implemented",
+    "i've implemented",
     "added",
     "i added",
+    "i've added",
     "updated",
     "i updated",
+    "i've updated",
     "modified",
     "i modified",
+    "i've modified",
     "created",
     "i created",
+    "i've created",
     "fixed",
     "i fixed",
+    "i've fixed",
     "completed the changes",
     "finished the changes",
+    "made the following changes",
+    "applied the fix",
+    "changes have been applied",
+    "wrote the code",
+    "refactored",
+    "i refactored",
 )
 
 
@@ -134,6 +147,29 @@ def _classify_agent_failure(detail: str) -> tuple[str, str]:
     )
 
 
+_WRITE_FAILURE_MARKERS = (
+    "permission denied",
+    "read-only file system",
+    "read only file system",
+    "operation not permitted",
+    "cannot write",
+    "failed to write",
+    "could not write",
+    "unable to write",
+    "sandbox",
+    "eacces",
+    "erofs",
+)
+
+
+def _has_write_failure_indicators(stderr: str) -> bool:
+    """Detect stderr patterns indicating the agent could not write files."""
+    if not stderr.strip():
+        return False
+    normalized = stderr.lower()
+    return any(marker in normalized for marker in _WRITE_FAILURE_MARKERS)
+
+
 def _claims_file_changes(output: str) -> bool:
     """Heuristic for agent text that claims code changes were made."""
     normalized = output.lower()
@@ -406,7 +442,8 @@ def invoke_agent_agentic(
         # (avoids OS arg length limits for large prompts)
         cmd.append(
             f"Read the task file at {task_file} and execute all instructions in it. "
-            f"Work in the current directory."
+            f"Work only inside the current directory and do not modify files "
+            f"outside it."
         )
 
     cmd_preview = " ".join(cmd[:6])
@@ -467,7 +504,14 @@ def invoke_agent_agentic(
     if not diff_output:
         stdout_excerpt = (result.stdout or "").strip()
         stderr_excerpt = (result.stderr or "").strip()
-        if _claims_file_changes(stdout_excerpt):
+
+        # Detect two failure modes:
+        # 1. Agent claims changes in stdout but produced no diff
+        # 2. Agent stderr contains permission or write-failure indicators
+        claims_changes = _claims_file_changes(stdout_excerpt)
+        has_write_failure = _has_write_failure_indicators(stderr_excerpt)
+
+        if claims_changes or has_write_failure:
             if spinner:
                 spinner.stop(f"[{step_name}] FAILED (empty diff)")
             raw_error = stdout_excerpt or "(stdout empty)"
@@ -475,16 +519,27 @@ def invoke_agent_agentic(
                 raw_error = f"{raw_error}\n\n[stderr]\n{stderr_excerpt}"
             if len(raw_error) > 2000:
                 raw_error = raw_error[:2000] + "..."
+
+            if has_write_failure:
+                failure_type = "WRITE_FAILURE"
+                suggested_action = (
+                    "Agent encountered file write errors (permission denied, read-only, "
+                    "or sandbox restriction). Check agent permissions and worktree state."
+                )
+            else:
+                failure_type = "EMPTY_DIFF"
+                suggested_action = (
+                    "Agent reported code changes but produced no git diff. "
+                    "Treat this run as failed and require a real worktree diff before continuing."
+                )
+
             raise AgentInvocationError(
                 agent_name=agent.name,
                 step_name=step_name,
                 cmd_preview=cmd_preview,
                 raw_error=raw_error,
-                failure_type="EMPTY_DIFF",
-                suggested_action=(
-                    "Agent reported code changes but produced no git diff. "
-                    "Treat this run as failed and require a real worktree diff before continuing."
-                ),
+                failure_type=failure_type,
+                suggested_action=suggested_action,
             )
 
         diff_output = "(no changes)"
diff --git a/cross_eval/pipeline.py b/cross_eval/pipeline.py
index 7047318..f42e681 100644
--- a/cross_eval/pipeline.py
+++ b/cross_eval/pipeline.py
@@ -6,6 +6,7 @@ import os
 import re
 import subprocess
 import time
+from hashlib import sha256
 from concurrent.futures import ThreadPoolExecutor, as_completed
 from datetime import datetime
 from pathlib import Path
@@ -92,15 +93,110 @@ def _setup_worktree(cwd: Path, run_dir: Path, preset_name: str) -> tuple[Path, s
 
     Returns (worktree_path, branch_name).
     """
-    from cross_eval.worktree import create_worktree, make_branch_name
+    from cross_eval.worktree import create_worktree, make_branch_name, make_worktree_dir
     branch_name = make_branch_name(preset_name)
-    worktree_dir = run_dir / "work"
+    worktree_dir = make_worktree_dir(cwd, branch_name)
     worktree_path = create_worktree(
         base_cwd=cwd, work_dir=worktree_dir, branch_name=branch_name,
     )
+    (run_dir / "worktree_path.txt").write_text(f"{worktree_path}\n", encoding="utf-8")
+    (run_dir / "worktree_branch.txt").write_text(f"{branch_name}\n", encoding="utf-8")
     return worktree_path, branch_name
 
 
+def _snapshot_repo_state(cwd: Path) -> str:
+    """Capture the base repository working-tree state.
+
+    This is used to detect agentic runs that accidentally modify the original
+    checkout instead of the isolated worktree.
+    """
+    status = subprocess.run(
+        ["git", "status", "--short", "--untracked-files=all"],
+        cwd=cwd,
+        capture_output=True,
+        text=True,
+    )
+    if status.returncode != 0:
+        return ""
+
+    diff = subprocess.run(
+        ["git", "diff", "--no-ext-diff", "--binary", "HEAD"],
+        cwd=cwd,
+        capture_output=True,
+        text=True,
+    )
+    cached_diff = subprocess.run(
+        ["git", "diff", "--no-ext-diff", "--binary", "--cached"],
+        cwd=cwd,
+        capture_output=True,
+        text=True,
+    )
+    untracked = subprocess.run(
+        ["git", "ls-files", "--others", "--exclude-standard", "-z"],
+        cwd=cwd,
+        capture_output=True,
+    )
+
+    parts = [
+        status.stdout,
+        diff.stdout,
+        cached_diff.stdout,
+    ]
+
+    if untracked.returncode == 0 and untracked.stdout:
+        for rel_path in untracked.stdout.decode("utf-8", errors="replace").split("\0"):
+            if not rel_path:
+                continue
+            file_path = cwd / rel_path
+            if file_path.is_file():
+                digest = sha256(file_path.read_bytes()).hexdigest()
+                parts.append(f"UNTRACKED {rel_path} {digest}")
+            else:
+                parts.append(f"UNTRACKED {rel_path} (non-file)")
+
+    return "\n".join(parts)
+
+
+def _snapshot_repo_status(cwd: Path) -> str:
+    """Capture a human-readable status summary for error reporting."""
+    result = subprocess.run(
+        ["git", "status", "--short", "--untracked-files=all"],
+        cwd=cwd,
+        capture_output=True,
+        text=True,
+    )
+    if result.returncode != 0:
+        return ""
+    return result.stdout.strip()
+
+
+def _assert_base_repo_isolation(
+    cwd: Path,
+    baseline_state: str,
+    *,
+    step_name: str,
+    agent_name: str,
+    worktree_path: Path,
+    baseline_status: str,
+) -> None:
+    """Fail fast if an agentic run leaked changes into the base repo."""
+    current_state = _snapshot_repo_state(cwd)
+    if current_state == baseline_state:
+        return
+
+    current_status = _snapshot_repo_status(cwd)
+    before = baseline_status or "(clean)"
+    after = current_status or "(clean)"
+    raise WorktreeError(
+        "Agent modified the base repository instead of the isolated worktree.\n\n"
+        f"Step: {step_name}\n"
+        f"Agent: {agent_name}\n"
+        f"Worktree: {worktree_path}\n\n"
+        f"Baseline status:\n{before}\n\n"
+        f"Current status:\n{after}"
+    )
+
+
 def _finalize_worktree(
     cwd: Path,
     worktree_path: Path,
@@ -172,10 +268,14 @@ def _run_simple_pipeline(
     # Setup shared worktree for agentic mode
     worktree_path: Path | None = None
     agentic_branch_name: str | None = None
+    base_repo_state: str | None = None
+    base_repo_status: str | None = None
     if not dry_run and _has_agentic_steps(config, config.pipeline):
         worktree_path, agentic_branch_name = _setup_worktree(
             cwd, run_dir, config.preset_name,
         )
+        base_repo_state = _snapshot_repo_state(cwd)
+        base_repo_status = _snapshot_repo_status(cwd)
 
     feedback = "(no feedback — first iteration)"
     iterations: list[IterationResult] = []
@@ -203,6 +303,8 @@ def _run_simple_pipeline(
                 run_dir=run_dir, output_iter=i,
                 worktree_path=worktree_path,
                 runtime_env=runtime_env,
+                base_repo_state=base_repo_state,
+                base_repo_status=base_repo_status,
             )
 
             # Intermediate commit so next iteration's diff only shows new changes
@@ -332,10 +434,14 @@ def _run_phased_pipeline(
     all_phase_steps = [s for p in config.phases for s in p.steps]
     worktree_path: Path | None = None
     agentic_branch_name: str | None = None
+    base_repo_state: str | None = None
+    base_repo_status: str | None = None
     if not dry_run and _has_agentic_steps(config, all_phase_steps):
         worktree_path, agentic_branch_name = _setup_worktree(
             cwd, run_dir, config.preset_name,
         )
+        base_repo_state = _snapshot_repo_state(cwd)
+        base_repo_status = _snapshot_repo_status(cwd)
 
     iterations: list[IterationResult] = []
     feedback = "(no feedback — first iteration)"
@@ -384,6 +490,8 @@ def _run_phased_pipeline(
                     run_dir=run_dir, output_iter=global_iter, phase_name=phase.name,
                     worktree_path=worktree_path,
                     runtime_env=runtime_env,
+                    base_repo_state=base_repo_state,
+                    base_repo_status=base_repo_status,
                 )
 
                 # Intermediate commit so next iteration's diff only shows new changes
@@ -626,6 +734,8 @@ def _run_steps(
     phase_name: str | None = None,
     worktree_path: Path | None = None,
     runtime_env: dict[str, str] | None = None,
+    base_repo_state: str | None = None,
+    base_repo_status: str | None = None,
 ) -> tuple[dict[str, str], dict[str, AgentResult], str | None]:
     """Execute all steps in one iteration, parallelizing where possible."""
     step_outputs: dict[str, str] = {}
@@ -644,6 +754,8 @@ def _run_steps(
                 run_dir=run_dir, output_iter=output_iter,
                 phase_name=phase_name, worktree_path=worktree_path,
                 runtime_env=runtime_env,
+                base_repo_state=base_repo_state,
+                base_repo_status=base_repo_status,
             )
         else:
             _execute_parallel_batch(
@@ -653,6 +765,8 @@ def _run_steps(
                 run_dir=run_dir, output_iter=output_iter,
                 phase_name=phase_name, worktree_path=worktree_path,
                 runtime_env=runtime_env,
+                base_repo_state=base_repo_state,
+                base_repo_status=base_repo_status,
             )
 
     # Extract verdict from all verdict steps (ALL must PASS; ESCALATE wins over all)
@@ -709,6 +823,8 @@ def _execute_step(
     quiet: bool = False,
     worktree_path: Path | None = None,
     runtime_env: dict[str, str] | None = None,
+    base_repo_state: str | None = None,
+    base_repo_status: str | None = None,
 ) -> None:
     """Execute a single step, updating step_outputs and step_results in place."""
     if not quiet:
@@ -717,9 +833,10 @@ def _execute_step(
     # 1. Resolve template
     template = resolve_template(step.prompt_template)
 
-    # 2. Build context
+    # 2. Build context (include prior step results for evidence)
     context = _build_context(
         input_contents, step_outputs, feedback, iteration, max_iterations,
+        step_results=step_results,
     )
 
     # 3. Apply context overrides
@@ -794,6 +911,16 @@ def _execute_step(
         raise
 
     # 7. Store output
+    if worktree_path is not None and base_repo_state is not None:
+        _assert_base_repo_isolation(
+            cwd,
+            base_repo_state,
+            step_name=step.name,
+            agent_name=step.agent,
+            worktree_path=worktree_path,
+            baseline_status=base_repo_status or "",
+        )
+
     step_outputs[step.output_key] = result.output
     step_results[step.output_key] = result
 
@@ -826,6 +953,8 @@ def _execute_parallel_batch(
     phase_name: str | None = None,
     worktree_path: Path | None = None,
     runtime_env: dict[str, str] | None = None,
+    base_repo_state: str | None = None,
+    base_repo_status: str | None = None,
 ) -> None:
     """Execute multiple steps in parallel using threads."""
     agent_names = ", ".join(s.agent for s in batch)
@@ -838,6 +967,8 @@ def _execute_parallel_batch(
                 iteration, max_iterations, cwd, timeout, dry_run,
                 step_outputs, step_results,
                 run_dir=run_dir, output_iter=output_iter, phase_name=phase_name,
+                base_repo_state=base_repo_state,
+                base_repo_status=base_repo_status,
             )
         return
 
@@ -858,12 +989,15 @@ def _execute_parallel_batch(
                 step_outputs, step_results,
                 run_dir=run_dir, output_iter=output_iter,
                 phase_name=phase_name, worktree_path=worktree_path,
+                base_repo_state=base_repo_state,
+                base_repo_status=base_repo_status,
             )
         return
 
     # Snapshot context before parallel execution (all steps see same state)
     context_snapshot = dict(input_contents)
     context_snapshot.update(step_outputs)
+    results_snapshot = dict(step_results)
 
     # Collect results from parallel threads
     local_outputs: dict[str, str] = {}
@@ -883,6 +1017,7 @@ def _execute_parallel_batch(
         template = resolve_template(step.prompt_template)
         context = _build_context(
             context_snapshot, {}, feedback, iteration, max_iterations,
+            step_results=results_snapshot,
         )
         if step.context_override:
             context = _apply_context_override(context, step.context_override)
@@ -919,6 +1054,16 @@ def _execute_parallel_batch(
     batch_elapsed = round(time.monotonic() - batch_start, 1)
 
     # Persist successful outputs even if a sibling step failed.
+    if worktree_path is not None and base_repo_state is not None:
+        _assert_base_repo_isolation(
+            cwd,
+            base_repo_state,
+            step_name=phase_name or "parallel-batch",
+            agent_name=agent_names,
+            worktree_path=worktree_path,
+            baseline_status=base_repo_status or "",
+        )
+
     for step in batch:
         key = step.output_key
         if key not in local_outputs:
@@ -986,6 +1131,7 @@ def _build_context(
     feedback: str,
     iteration: int,
     max_iterations: int,
+    step_results: dict[str, AgentResult] | None = None,
 ) -> dict[str, str]:
     """Build the template context dict."""
     context: dict[str, str] = {}
@@ -994,9 +1140,42 @@ def _build_context(
     context["feedback"] = feedback
     context["iteration"] = str(iteration)
     context["max_iterations"] = str(max_iterations)
+    # Surface execution evidence from prior steps so reviewers can inspect it
+    if step_results:
+        context["execution_evidence"] = _format_execution_evidence(step_results)
     return context
 
 
+def _format_execution_evidence(
+    step_results: dict[str, AgentResult],
+) -> str:
+    """Format execution evidence from prior steps for reviewer consumption.
+
+    Produces a compact summary of command, exit code, duration, and a truncated
+    transcript excerpt for each completed step so that reviewers and seniors
+    can verify claims against real execution data.
+    """
+    if not step_results:
+        return "(no prior execution evidence)"
+    parts: list[str] = []
+    for key, result in step_results.items():
+        section = [
+            f"### Step: {result.step_name} ({result.agent_name})",
+            f"- Command: `{result.command_preview}`" if result.command_preview else "",
+            f"- Exit code: {result.exit_code}",
+            f"- Duration: {result.duration_seconds}s",
+        ]
+        section = [line for line in section if line]
+        if result.transcript:
+            # Include a truncated transcript excerpt for debugging
+            excerpt = result.transcript[:2000]
+            if len(result.transcript) > 2000:
+                excerpt += "\n... (truncated)"
+            section.append(f"\n<details>\n<summary>Transcript excerpt</summary>\n\n{excerpt}\n</details>")
+        parts.append("\n".join(section))
+    return "\n\n---\n\n".join(parts)
+
+
 def _build_runtime_inputs(
     config: PipelineConfig,
     input_contents: dict[str, str],
diff --git a/cross_eval/prompts.py b/cross_eval/prompts.py
index 48f1183..e6daa74 100644
--- a/cross_eval/prompts.py
+++ b/cross_eval/prompts.py
@@ -59,9 +59,14 @@ You are tasked with reviewing code against a plan and checklist.
 ## Previous Review Feedback
 {feedback}
 
+## Execution Evidence
+{execution_evidence}
+
 ## Review Instructions
 Explore the project directory to understand the full codebase context, \
-then evaluate the code against ONLY the plan and checklist above.
+then evaluate the code against ONLY the plan and checklist above. \
+Use the execution evidence above to verify agent claims against actual \
+command outputs and exit codes.
 
 For each issue found, classify it with BOTH severity AND category:
 
@@ -164,9 +169,13 @@ REVIEW_TEMPLATE_KO = """\
 ## 이전 리뷰 피드백
 {feedback}
 
+## 실행 증거
+{execution_evidence}
+
 ## 검토 지침
 프로젝트 디렉토리를 직접 탐색하여 전체 코드베이스 맥락을 파악한 뒤, \
-위 기획서와 체크리스트 기준으로만 코드를 평가하세요.
+위 기획서와 체크리스트 기준으로만 코드를 평가하세요. \
+위 실행 증거를 활용하여 에이전트의 주장을 실제 명령어 출력과 종료 코드로 검증하세요.
 
 발견된 각 이슈에 심각도와 카테고리를 모두 부여하세요:
 
@@ -525,8 +534,13 @@ You are adjudicating multiple review results and turning them into an actionable
 ## Previous Issue Tracker
 {previous_senior_tracker}
 
+## Execution Evidence
+{execution_evidence}
+
 ## Instructions
-Explore the project directory to confirm the current codebase state. Then:
+Explore the project directory to confirm the current codebase state. \
+Use the execution evidence above to verify claims against actual command \
+outputs and exit codes. Then:
 1. Deduplicate overlapping issues across reviewers.
 2. Resolve disagreements explicitly.
 3. Keep only issues supported by the plan, checklist, code, or reviewer evidence.
@@ -592,8 +606,13 @@ AGGREGATE_REVIEW_TEMPLATE_KO = """\
 ## 이전 이슈 트래커
 {previous_senior_tracker}
 
+## 실행 증거
+{execution_evidence}
+
 ## 지침
-프로젝트 디렉토리를 탐색하여 현재 코드베이스 상태를 확인한 뒤 다음을 수행하세요.
+프로젝트 디렉토리를 탐색하여 현재 코드베이스 상태를 확인한 뒤, \
+위 실행 증거를 활용하여 에이전트의 주장을 실제 명령어 출력과 종료 코드로 검증하세요. \
+그런 다음 아래를 수행하세요.
 1. 리뷰어들 사이에 중복되는 이슈를 합치세요.
 2. 의견 충돌은 명시적으로 정리하세요.
 3. 기획서, 체크리스트, 코드, 리뷰 근거로 뒷받침되는 이슈만 남기세요.
diff --git a/cross_eval/report.py b/cross_eval/report.py
index eda32ea..a7cbc6d 100644
--- a/cross_eval/report.py
+++ b/cross_eval/report.py
@@ -386,6 +386,11 @@ def _append_iteration_steps(
 
         lines.append(f"### {_t(config, 'step')}: {step.name} ({agent_name}){duration}\n")
 
+        # Show command preview and exit code for execution evidence
+        if agent_result and agent_result.command_preview:
+            lines.append(f"**Command**: `{agent_result.command_preview}`")
+            lines.append(f"**Exit code**: {agent_result.exit_code}\n")
+
         if step.verdict and iter_result.verdict:
             lines.append(f"**{_t(config, 'verdict')}: {iter_result.verdict}**\n")
 
@@ -400,6 +405,16 @@ def _append_iteration_steps(
             lines.append(output)
             lines.append("")
 
+        # Include transcript excerpt for execution evidence visibility
+        if agent_result and agent_result.transcript:
+            transcript_preview = agent_result.transcript[:1500]
+            if len(agent_result.transcript) > 1500:
+                transcript_preview += "\n... (truncated)"
+            lines.append("<details>")
+            lines.append("<summary>Execution transcript</summary>\n")
+            lines.append(transcript_preview)
+            lines.append("\n</details>\n")
+
         if not skip_extraction and step.role == "review":
             oos = _extract_out_of_scope(output)
             if oos:
diff --git a/cross_eval/worktree.py b/cross_eval/worktree.py
index dda710f..7fd0932 100644
--- a/cross_eval/worktree.py
+++ b/cross_eval/worktree.py
@@ -4,6 +4,7 @@ from __future__ import annotations
 import logging
 import shutil
 import subprocess
+import tempfile
 from datetime import datetime
 from pathlib import Path
 
@@ -20,6 +21,22 @@ def make_branch_name(preset_name: str) -> str:
     return f"cross-eval/{preset_name}_{ts}"
 
 
+def make_worktree_dir(base_cwd: Path, branch_name: str) -> Path:
+    """Choose a worktree directory outside the base repo.
+
+    Keeping agentic worktrees outside the source checkout avoids tools that
+    incorrectly walk up to the outer repo and write into the base worktree.
+    """
+    repo_name = base_cwd.resolve().name or "repo"
+    branch_slug = branch_name.replace("/", "__")
+    return (
+        Path(tempfile.gettempdir())
+        / "cross-eval-worktrees"
+        / repo_name
+        / branch_slug
+    )
+
+
 def create_worktree(base_cwd: Path, work_dir: Path, branch_name: str) -> Path:
     """Create a git worktree on a new branch from HEAD.
 
diff --git a/tests/test_agentic.py b/tests/test_agentic.py
index dc3768f..178bf63 100644
--- a/tests/test_agentic.py
+++ b/tests/test_agentic.py
@@ -23,6 +23,7 @@ from cross_eval.models import (
     StepConfig,
 )
 from cross_eval.pipeline import (
+    _assert_base_repo_isolation,
     _commit_iteration,
     _finalize_worktree,
     _has_agentic_steps,
@@ -34,6 +35,7 @@ from cross_eval.worktree import (
     commit_worktree,
     create_worktree,
     make_branch_name,
+    make_worktree_dir,
     remove_worktree,
 )
 
@@ -191,6 +193,41 @@ class TestMakeBranchName(unittest.TestCase):
         self.assertEqual(len(ts_part), 15)  # YYYYMMDD_HHMMSS
 
 
+class TestMakeWorktreeDir(unittest.TestCase):
+    """make_worktree_dir chooses an external temp location."""
+
+    def test_uses_tmp_dir_outside_repo(self) -> None:
+        with tempfile.TemporaryDirectory() as td:
+            base = Path(td) / "repo"
+            base.mkdir()
+            path = make_worktree_dir(base, "cross-eval/review-fix_20260313_123456")
+            self.assertIn("cross-eval-worktrees", str(path))
+            self.assertNotIn(str(base), str(path))
+
+
+class TestBaseRepoIsolation(unittest.TestCase):
+    """Base repo mutations should fail fast during agentic execution."""
+
+    def test_raises_when_base_repo_status_changes(self) -> None:
+        with tempfile.TemporaryDirectory() as td:
+            base = Path(td) / "repo"
+            worktree = Path(td) / "worktree"
+            base.mkdir()
+            worktree.mkdir()
+
+            with self.assertRaises(RuntimeError) as ctx:
+                _assert_base_repo_isolation(
+                    base,
+                    "M cross_eval/agent.py",
+                    step_name="coding",
+                    agent_name="claude-coder",
+                    worktree_path=worktree,
+                    baseline_status="M cross_eval/agent.py",
+                )
+
+        self.assertIn("base repository", str(ctx.exception))
+
+
 # ===================================================================
 # 2. agent.py agentic tests (mocking subprocess)
 # ===================================================================
@@ -513,6 +550,33 @@ class TestSetupWorktreeCalledForAgentic(unittest.TestCase):
             mock_setup.assert_called_once()
 
 
+class TestSetupWorktreeLocation(unittest.TestCase):
+    """_setup_worktree places agentic worktrees outside the base repo."""
+
+    def test_worktree_is_created_outside_repo(self) -> None:
+        with tempfile.TemporaryDirectory() as td:
+            base = Path(td) / "repo"
+            run_dir = base / ".cross-eval" / "output" / "smoke"
+            base.mkdir()
+            run_dir.mkdir(parents=True)
+            _init_git_repo(base)
+
+            worktree_path, branch_name = _setup_worktree(base, run_dir, "review-fix")
+            try:
+                self.assertTrue(worktree_path.exists())
+                self.assertNotIn(str(base.resolve()), str(worktree_path.resolve()))
+                self.assertEqual(
+                    (run_dir / "worktree_path.txt").read_text(encoding="utf-8").strip(),
+                    str(worktree_path),
+                )
+                self.assertEqual(
+                    (run_dir / "worktree_branch.txt").read_text(encoding="utf-8").strip(),
+                    branch_name,
+                )
+            finally:
+                remove_worktree(base, worktree_path)
+
+
 class TestReviewerRunsInWorktreeCwd(unittest.TestCase):
     """Reviewer runs with worktree cwd (not original cwd) when worktree exists."""
 
diff --git a/tests/test_evidence.py b/tests/test_evidence.py
new file mode 100644
index 0000000..fc66682
--- /dev/null
+++ b/tests/test_evidence.py
@@ -0,0 +1,395 @@
+"""Regression tests for runtime evidence propagation and report visibility.
+
+Covers:
+  1. Execution evidence is surfaced in reviewer/senior prompt context.
+  2. Reports include command preview and transcript excerpts.
+  3. Claude agentic failure detection (empty diff, write failure, expanded markers).
+  4. _format_execution_evidence produces expected output.
+"""
+from __future__ import annotations
+
+import tempfile
+import unittest
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+from cross_eval.agent import (
+    AgentInvocationError,
+    _claims_file_changes,
+    _has_write_failure_indicators,
+    invoke_agent_agentic,
+)
+from cross_eval.config import BUILTIN_AGENTS
+from cross_eval.models import (
+    AgentConfig,
+    AgentResult,
+    IterationResult,
+    PipelineConfig,
+    PipelineResult,
+    ReviewMetrics,
+    StepConfig,
+)
+from cross_eval.pipeline import _format_execution_evidence, run_pipeline
+from cross_eval.report import build_report
+
+
+# ---------------------------------------------------------------------------
+# 1. Execution evidence formatting
+# ---------------------------------------------------------------------------
+
+class TestFormatExecutionEvidence(unittest.TestCase):
+    """_format_execution_evidence produces a compact summary for reviewers."""
+
+    def test_empty_results_returns_placeholder(self) -> None:
+        self.assertIn("no prior execution evidence", _format_execution_evidence({}))
+
+    def test_single_result_includes_key_fields(self) -> None:
+        result = AgentResult(
+            output="some diff",
+            exit_code=0,
+            agent_name="claude-coder",
+            step_name="coding",
+            duration_seconds=12.3,
+            transcript="# Agent Execution Transcript\n\n## Command\nclaude ...",
+            command_preview="claude --setting-sources user",
+        )
+        evidence = _format_execution_evidence({"coding_output": result})
+        self.assertIn("claude-coder", evidence)
+        self.assertIn("coding", evidence)
+        self.assertIn("Exit code: 0", evidence)
+        self.assertIn("12.3s", evidence)
+        self.assertIn("claude --setting-sources user", evidence)
+        self.assertIn("Transcript excerpt", evidence)
+
+    def test_multiple_results_separated(self) -> None:
+        r1 = AgentResult(
+            output="diff1", exit_code=0, agent_name="coder",
+            step_name="coding", duration_seconds=1.0,
+            command_preview="cmd1",
+        )
+        r2 = AgentResult(
+            output="review text", exit_code=0, agent_name="reviewer",
+            step_name="review", duration_seconds=2.0,
+            command_preview="cmd2",
+        )
+        evidence = _format_execution_evidence({
+            "coding_output": r1,
+            "review_result": r2,
+        })
+        self.assertIn("coder", evidence)
+        self.assertIn("reviewer", evidence)
+        self.assertIn("---", evidence)
+
+    def test_transcript_truncated_at_2000_chars(self) -> None:
+        long_transcript = "x" * 3000
+        result = AgentResult(
+            output="out", exit_code=0, agent_name="agent",
+            step_name="step", duration_seconds=1.0,
+            transcript=long_transcript,
+        )
+        evidence = _format_execution_evidence({"key": result})
+        self.assertIn("truncated", evidence)
+        # The full 3000-char transcript should NOT appear
+        self.assertNotIn("x" * 3000, evidence)
+
+
+# ---------------------------------------------------------------------------
+# 2. Evidence in reviewer prompts (integration)
+# ---------------------------------------------------------------------------
+
+class TestEvidenceInReviewerPrompt(unittest.TestCase):
+    """Reviewer prompts include execution evidence from prior coding step."""
+
+    def test_reviewer_receives_evidence(self) -> None:
+        with tempfile.TemporaryDirectory() as tmpdir:
+            steps = [
+                StepConfig(
+                    name="coding", agent="claude-coder", role="coding",
+                    prompt_template="default:coding", output_key="coding_output",
+                ),
+                StepConfig(
+                    name="review", agent="claude-reviewer", role="review",
+                    prompt_template="default:review", output_key="review_result",
+                    verdict=True,
+                ),
+            ]
+            config = PipelineConfig(
+                output_dir=Path(tmpdir),
+                max_iterations=1,
+                min_iterations=1,
+                language="en",
+                inputs={"plan": "Test plan", "checklist": "Test checklist"},
+                agents=dict(BUILTIN_AGENTS),
+                coders=["claude-coder"],
+                reviewers=["claude-reviewer"],
+                pipeline=steps,
+                preset_name="simple",
+            )
+
+            captured_prompts: list[dict] = []
+
+            def _mock(agent_config, prompt, step_name, **kwargs):
+                captured_prompts.append({
+                    "step_name": step_name,
+                    "prompt": prompt,
+                })
+                if step_name == "coding":
+                    return AgentResult(
+                        output="Implemented feature X",
+                        exit_code=0,
+                        agent_name=agent_config.name,
+                        step_name=step_name,
+                        duration_seconds=5.0,
+                        transcript="# Transcript\nclaude ran...",
+                        command_preview="claude --setting-sources user",
+                    )
+                return AgentResult(
+                    output="VERDICT: PASS",
+                    exit_code=0,
+                    agent_name=agent_config.name,
+                    step_name=step_name,
+                    duration_seconds=2.0,
+                )
+
+            with patch("cross_eval.pipeline.invoke_agent", side_effect=_mock):
+                result = run_pipeline(config)
+
+            self.assertEqual(result.final_verdict, "PASS")
+
+            # The reviewer prompt should contain execution evidence
+            review_prompts = [
+                p for p in captured_prompts if p["step_name"] == "review"
+            ]
+            self.assertTrue(len(review_prompts) >= 1)
+            review_prompt = review_prompts[0]["prompt"]
+            # Evidence section should reference the coding step's command
+            self.assertIn("Execution Evidence", review_prompt)
+            self.assertIn("claude-coder", review_prompt)
+
+
+# ---------------------------------------------------------------------------
+# 3. Report includes evidence
+# ---------------------------------------------------------------------------
+
+class TestReportIncludesEvidence(unittest.TestCase):
+    """Report generation includes command preview and transcript excerpts."""
+
+    def _make_pipeline_result(self) -> tuple[PipelineConfig, PipelineResult]:
+        steps = [
+            StepConfig(
+                name="coding", agent="claude-coder", role="coding",
+                prompt_template="default:coding", output_key="coding_output",
+            ),
+            StepConfig(
+                name="review", agent="claude-reviewer", role="review",
+                prompt_template="default:review", output_key="review_result",
+                verdict=True,
+            ),
+        ]
+        config = PipelineConfig(
+            max_iterations=1,
+            language="en",
+            inputs={"plan": "Plan", "checklist": "CL"},
+            agents=dict(BUILTIN_AGENTS),
+            pipeline=steps,
+            preset_name="simple",
+        )
+
+        coding_result = AgentResult(
+            output="diff --git a/file ...",
+            exit_code=0,
+            agent_name="claude-coder",
+            step_name="coding",
+            duration_seconds=10.0,
+            transcript="# Agent Execution Transcript\n## Command\nclaude ...\n## Stdout\nok",
+            command_preview="claude --setting-sources user",
+        )
+        review_result = AgentResult(
+            output="All good.\n\nVERDICT: PASS",
+            exit_code=0,
+            agent_name="claude-reviewer",
+            step_name="review",
+            duration_seconds=5.0,
+            transcript="# Agent Execution Transcript\n## Command\nclaude -p ...\n## Stdout\nAll good.",
+            command_preview="claude -p --setting-sources user",
+        )
+
+        iteration = IterationResult(
+            iteration=1,
+            step_results={
+                "coding_output": coding_result,
+                "review_result": review_result,
+            },
+            step_outputs={
+                "coding_output": "diff --git a/file ...",
+                "review_result": "All good.\n\nVERDICT: PASS",
+            },
+            verdict="PASS",
+        )
+
+        pipeline_result = PipelineResult(
+            iterations=[iteration],
+            final_verdict="PASS",
+            total_duration=15.0,
+        )
+
+        return config, pipeline_result
+
+    def test_report_contains_command_preview(self) -> None:
+        config, result = self._make_pipeline_result()
+        report = build_report(config, result)
+        self.assertIn("claude --setting-sources user", report)
+        self.assertIn("**Command**", report)
+
+    def test_report_contains_transcript_excerpt(self) -> None:
+        config, result = self._make_pipeline_result()
+        report = build_report(config, result)
+        self.assertIn("Execution transcript", report)
+        self.assertIn("Agent Execution Transcript", report)
+
+    def test_report_contains_exit_code(self) -> None:
+        config, result = self._make_pipeline_result()
+        report = build_report(config, result)
+        self.assertIn("**Exit code**: 0", report)
+
+
+# ---------------------------------------------------------------------------
+# 4. Claude agentic hardened failure detection
+# ---------------------------------------------------------------------------
+
+class TestClaimsFileChangesExpanded(unittest.TestCase):
+    """Expanded change-claim markers detect more Claude output patterns."""
+
+    def test_ive_implemented(self) -> None:
+        self.assertTrue(_claims_file_changes("I've implemented the feature"))
+
+    def test_ive_updated(self) -> None:
+        self.assertTrue(_claims_file_changes("I've updated the config"))
+
+    def test_made_the_following_changes(self) -> None:
+        self.assertTrue(_claims_file_changes("I made the following changes to the file"))
+
+    def test_applied_the_fix(self) -> None:
+        self.assertTrue(_claims_file_changes("Applied the fix for the bug"))
+
+    def test_changes_have_been_applied(self) -> None:
+        self.assertTrue(_claims_file_changes("Changes have been applied successfully"))
+
+    def test_wrote_the_code(self) -> None:
+        self.assertTrue(_claims_file_changes("Wrote the code for the new module"))
+
+    def test_refactored(self) -> None:
+        self.assertTrue(_claims_file_changes("I refactored the pipeline"))
+
+    def test_no_changes_still_returns_false(self) -> None:
+        self.assertFalse(_claims_file_changes("No changes were necessary"))
+
+    def test_empty_string_returns_false(self) -> None:
+        self.assertFalse(_claims_file_changes(""))
+
+
+class TestWriteFailureIndicators(unittest.TestCase):
+    """_has_write_failure_indicators detects stderr patterns."""
+
+    def test_permission_denied(self) -> None:
+        self.assertTrue(_has_write_failure_indicators("Error: Permission denied"))
+
+    def test_read_only_filesystem(self) -> None:
+        self.assertTrue(_has_write_failure_indicators("read-only file system"))
+
+    def test_sandbox_restriction(self) -> None:
+        self.assertTrue(_has_write_failure_indicators("Blocked by sandbox policy"))
+
+    def test_eacces(self) -> None:
+        self.assertTrue(_has_write_failure_indicators("EACCES: operation not permitted"))
+
+    def test_empty_stderr_returns_false(self) -> None:
+        self.assertFalse(_has_write_failure_indicators(""))
+
+    def test_normal_stderr_returns_false(self) -> None:
+        self.assertFalse(_has_write_failure_indicators("Downloading model..."))
+
+
+class TestAgenticWriteFailureRaisesError(unittest.TestCase):
+    """Agentic mode raises AgentInvocationError on stderr write-failure indicators."""
+
+    @patch("cross_eval.worktree.capture_diff", return_value="")
+    @patch("subprocess.run")
+    def test_write_failure_detected_from_stderr(
+        self, mock_run: MagicMock, mock_diff: MagicMock,
+    ) -> None:
+        mock_run.return_value = MagicMock(
+            returncode=0,
+            stdout="Done.",
+            stderr="Error: Permission denied writing to /src/main.py",
+        )
+
+        agent = AgentConfig(
+            name="claude-coder", command="claude",
+            args=["--setting-sources", "user"], agentic=True,
+        )
+
+        import subprocess as _sp
+        import tempfile as _tf
+
+        with _tf.TemporaryDirectory() as td:
+            wt = Path(td)
+            _sp.run(["git", "init"], cwd=wt, capture_output=True, check=True)
+            _sp.run(["git", "config", "user.email", "t@t.com"], cwd=wt, capture_output=True)
+            _sp.run(["git", "config", "user.name", "T"], cwd=wt, capture_output=True)
+            (wt / "README.md").write_text("# init\n")
+            _sp.run(["git", "add", "."], cwd=wt, capture_output=True, check=True)
+            _sp.run(["git", "commit", "-m", "init"], cwd=wt, capture_output=True, check=True)
+
+            with self.assertRaises(AgentInvocationError) as ctx:
+                invoke_agent_agentic(
+                    agent, "implement feature", "coding",
+                    worktree_path=wt, quiet=True,
+                )
+
+        self.assertEqual(ctx.exception.failure_type, "WRITE_FAILURE")
+        self.assertIn("Permission denied", ctx.exception.raw_error)
+
+
+class TestAgenticExpandedClaimMarkers(unittest.TestCase):
+    """Agentic mode detects expanded claim markers in empty diff scenarios."""
+
+    @patch("cross_eval.worktree.capture_diff", return_value="")
+    @patch("subprocess.run")
+    def test_ive_implemented_triggers_empty_diff_error(
+        self, mock_run: MagicMock, mock_diff: MagicMock,
+    ) -> None:
+        mock_run.return_value = MagicMock(
+            returncode=0,
+            stdout="I've implemented the requested changes to the pipeline.",
+            stderr="",
+        )
+
+        agent = AgentConfig(
+            name="claude-coder", command="claude",
+            args=["--setting-sources", "user"], agentic=True,
+        )
+
+        import subprocess as _sp
+        import tempfile as _tf
+
+        with _tf.TemporaryDirectory() as td:
+            wt = Path(td)
+            _sp.run(["git", "init"], cwd=wt, capture_output=True, check=True)
+            _sp.run(["git", "config", "user.email", "t@t.com"], cwd=wt, capture_output=True)
+            _sp.run(["git", "config", "user.name", "T"], cwd=wt, capture_output=True)
+            (wt / "README.md").write_text("# init\n")
+            _sp.run(["git", "add", "."], cwd=wt, capture_output=True, check=True)
+            _sp.run(["git", "commit", "-m", "init"], cwd=wt, capture_output=True, check=True)
+
+            with self.assertRaises(AgentInvocationError) as ctx:
+                invoke_agent_agentic(
+                    agent, "implement feature", "coding",
+                    worktree_path=wt, quiet=True,
+                )
+
+        self.assertEqual(ctx.exception.failure_type, "EMPTY_DIFF")
+
+
+if __name__ == "__main__":
+    unittest.main()