diff --git a/solstone/think/cogitate_contract.py b/solstone/think/cogitate_contract.py
index f2826a9c5..914ca60bc 100644
--- a/solstone/think/cogitate_contract.py
+++ b/solstone/think/cogitate_contract.py
@@ -42,6 +42,9 @@ COGITATE_ACCESS_TIERS = (
     "synthesis",
     "diagnostic",
 )
+TALENT_ACCESS_TIERS = tuple(
+    tier for tier in COGITATE_ACCESS_TIERS if tier != "diagnostic"
+)
 
 # `code-agent` is a documented FUTURE tier — NOT part of the current cogitate
 # runtime (it needs write access, broad tools, and a repo cwd, deliberately out of
@@ -110,6 +113,7 @@ __all__ = [
     "COGITATE_ACCESS_TIERS",
     "COGITATE_READ_TOOL_NAMES",
     "FUTURE_ACCESS_TIERS",
+    "TALENT_ACCESS_TIERS",
     "TALENT_FINALIZATION_MODES",
     "capabilities_for_access_tier",
     "expects_emit_final",
diff --git a/solstone/think/providers/openhands.py b/solstone/think/providers/openhands.py
index 24ee320dd..3e056d1a2 100644
--- a/solstone/think/providers/openhands.py
+++ b/solstone/think/providers/openhands.py
@@ -18,6 +18,7 @@ import os
 import re
 import shutil
 import sys
+import tempfile
 import threading
 import traceback
 import uuid
@@ -1604,6 +1605,7 @@ async def run_cogitate(
 
     llm: Any | None = None
     usage_start: dict[str, int] | None = None
+    persistence_tmpdir: tempfile.TemporaryDirectory[str] | None = None
     try:
         with _openhands_import_policy():
             from openhands.sdk import Conversation
@@ -1678,8 +1680,14 @@ async def run_cogitate(
             system_prompt=system_instruction,
         )
 
-        persistence_dir = journal / ".cache" / "cogitate-history" / session_id
-        persistence_dir.mkdir(parents=True, exist_ok=True)
+        if diagnostic:
+            persistence_tmpdir = tempfile.TemporaryDirectory(
+                prefix="solstone-cogitate-diagnostic-"
+            )
+            persistence_dir = Path(persistence_tmpdir.name)
+        else:
+            persistence_dir = journal / ".cache" / "cogitate-history" / session_id
+            persistence_dir.mkdir(parents=True, exist_ok=True)
         translator = _OpenHandsTranslator(
             callback=callback,
             llm=llm,
@@ -1899,6 +1907,9 @@ async def run_cogitate(
         callback.emit(error_event)
         setattr(exc, "_evented", True)
         raise
+    finally:
+        if persistence_tmpdir is not None:
+            persistence_tmpdir.cleanup()
 
 
 def run_generate(
diff --git a/solstone/think/talent.py b/solstone/think/talent.py
index c870433ac..a53c4eb66 100644
--- a/solstone/think/talent.py
+++ b/solstone/think/talent.py
@@ -30,7 +30,7 @@ from typing import Any, Callable
 import frontmatter
 from jsonschema import Draft202012Validator, SchemaError
 
-from solstone.think.cogitate_contract import COGITATE_ACCESS_TIERS
+from solstone.think.cogitate_contract import TALENT_ACCESS_TIERS
 from solstone.think.facets import get_facets
 
 # Import core prompt utilities from solstone.think.prompts
@@ -92,11 +92,11 @@ def _validate_access_tier(raw: Any, talent_type: Any, key: str) -> str | None:
     if talent_type == "cogitate":
         if raw is None:
             return "normal"
-        if raw in COGITATE_ACCESS_TIERS:
+        if raw in TALENT_ACCESS_TIERS:
             return raw
         raise ValueError(
             f"Prompt '{key}' has invalid 'access_tier' value '{raw}' "
-            f"(must be one of {COGITATE_ACCESS_TIERS})"
+            f"(must be one of {TALENT_ACCESS_TIERS})"
         )
 
     if raw is not None:
diff --git a/tests/test_cogitate_contract.py b/tests/test_cogitate_contract.py
index 1560285d8..555a6e288 100644
--- a/tests/test_cogitate_contract.py
+++ b/tests/test_cogitate_contract.py
@@ -12,6 +12,7 @@ from solstone.think.cogitate_contract import (
     COGITATE_READ_TOOL_NAMES,
     COGITATE_RUNTIME_PREAMBLE,
     FUTURE_ACCESS_TIERS,
+    TALENT_ACCESS_TIERS,
     TALENT_FINALIZATION_MODES,
     expects_emit_final,
 )
@@ -81,6 +82,12 @@ def test_cogitate_vocabulary_lock():
         "grep_search",
     )
     assert FUTURE_ACCESS_TIERS == ("code-agent",)
+    assert TALENT_ACCESS_TIERS == (
+        "normal",
+        "system-read",
+        "outbound",
+        "synthesis",
+    )
     assert TALENT_FINALIZATION_MODES == ("emit_final", "FinishTool", "quiet")
     assert "repair" not in COGITATE_ACCESS_TIERS
     assert "repair" not in FUTURE_ACCESS_TIERS
diff --git a/tests/test_cogitate_diagnostic.py b/tests/test_cogitate_diagnostic.py
index 0388dfc05..f1baa58c4 100644
--- a/tests/test_cogitate_diagnostic.py
+++ b/tests/test_cogitate_diagnostic.py
@@ -4,6 +4,7 @@
 from __future__ import annotations
 
 import asyncio
+from pathlib import Path
 from types import SimpleNamespace
 
 from solstone.think.cogitate_contract import (
@@ -94,15 +95,24 @@ def test_diagnostic_run_registers_only_emit_final_and_writes_no_files(
     _install_emit_final_arun(fake_openhands, "diagnostic ok")
     config = _run_config(monkeypatch, tmp_path)
     events: list[dict] = []
+    created_temp_dirs: list[Path] = []
 
-    before_files = {path.relative_to(tmp_path) for path in tmp_path.rglob("*")}
+    real_tempdir = openhands.tempfile.TemporaryDirectory
+
+    def tracking_tempdir(*args, **kwargs):
+        kwargs.setdefault("dir", tmp_path.parent)
+        tempdir = real_tempdir(*args, **kwargs)
+        created_temp_dirs.append(Path(tempdir.name))
+        return tempdir
+
+    monkeypatch.setattr(openhands.tempfile, "TemporaryDirectory", tracking_tempdir)
+
+    before_tree = {path.relative_to(tmp_path) for path in tmp_path.rglob("*")}
     result = asyncio.run(openhands.run_cogitate(config, events.append))
 
     conversation = fake_openhands.Conversation.instances[0]
     agent_tool_names = {tool.name for tool in conversation.agent.tools}
-    after_files = {
-        path.relative_to(tmp_path) for path in tmp_path.rglob("*") if path.is_file()
-    }
+    after_tree = {path.relative_to(tmp_path) for path in tmp_path.rglob("*")}
 
     assert result == "diagnostic ok"
     assert agent_tool_names == {"emit_final"}
@@ -119,7 +129,9 @@ def test_diagnostic_run_registers_only_emit_final_and_writes_no_files(
     assert "grep_search" not in conversation.agent.system_prompt
     assert "through the `sol` tool" not in conversation.agent.system_prompt
     assert "sol call" not in conversation.agent.system_prompt
-    assert before_files == set()
-    assert after_files == set()
+    assert before_tree == set()
+    assert after_tree == set()
+    assert created_temp_dirs
+    assert not any(path.exists() for path in created_temp_dirs)
     assert [event["event"] for event in events] == ["finish"]
     assert events[0]["result"] == "diagnostic ok"
diff --git a/tests/test_talent.py b/tests/test_talent.py
index fef4f7e4e..f25a4076a 100644
--- a/tests/test_talent.py
+++ b/tests/test_talent.py
@@ -123,6 +123,14 @@ def test_validate_access_tier_rejects_unknown_tier():
         _validate_access_tier("repair", "cogitate", "test-agent")
 
 
+def test_validate_access_tier_rejects_internal_diagnostic_tier():
+    with pytest.raises(
+        ValueError,
+        match="Prompt 'test-agent' has invalid 'access_tier' value 'diagnostic'",
+    ):
+        _validate_access_tier("diagnostic", "cogitate", "test-agent")
+
+
 def test_validate_access_tier_rejects_generate_with_access_tier():
     with pytest.raises(
         ValueError,