diff --git a/harness/tests/test_doctor_cli.py b/harness/tests/test_doctor_cli.py
index 1b40418c..58f195df 100644
--- a/harness/tests/test_doctor_cli.py
+++ b/harness/tests/test_doctor_cli.py
@@ -90,7 +90,67 @@ def test_doctor_json_does_not_echo_invalid_config_values(monkeypatch, tmp_path):
     payload = json.loads(result.stdout)
     assert payload["components"]["config"] == {
         "status": "error",
-        "message": "configuration is invalid",
+        "message": "configuration is invalid or unreadable",
     }
     assert "super-secret" not in result.stdout
     assert "pii_user" not in result.stdout
+
+
+def test_doctor_json_normalizes_malformed_yaml(monkeypatch, tmp_path):
+    cfg = tmp_path / "demo.yaml"
+    cfg.write_text("password: super-secret\nroots: [unterminated")
+    monkeypatch.setenv("THT_DATA_ROOT", str(tmp_path / "data"))
+
+    result = runner.invoke(app, ["doctor", "--json", "--config", str(cfg)])
+
+    assert result.exit_code == 1
+    assert json.loads(result.stdout)["components"]["config"] == {
+        "status": "error",
+        "message": "configuration is invalid or unreadable",
+    }
+    assert result.stderr == ""
+    assert "super-secret" not in result.stdout
+    assert "Traceback" not in result.stdout
+
+
+def test_doctor_json_normalizes_unreadable_config(monkeypatch, tmp_path):
+    cfg = tmp_path / "demo.yaml"
+    cfg.mkdir()
+    monkeypatch.setenv("THT_DATA_ROOT", str(tmp_path / "data"))
+
+    result = runner.invoke(app, ["doctor", "--json", "--config", str(cfg)])
+
+    assert result.exit_code == 1
+    assert json.loads(result.stdout)["components"]["config"] == {
+        "status": "error",
+        "message": "configuration is invalid or unreadable",
+    }
+    assert result.stderr == ""
+
+
+def test_doctor_human_output_is_actionable_and_redacted(monkeypatch, tmp_path):
+    cfg = _config(tmp_path / "demo.yaml", absolute_sessions=tmp_path / "patient-private")
+    monkeypatch.delenv("THT_DATA_ROOT", raising=False)
+
+    result = runner.invoke(app, ["doctor", "--config", str(cfg)])
+
+    assert result.exit_code == 0
+    assert "data_root: warning - set THT_DATA_ROOT to enable portable storage" in result.stdout
+    assert "workspace_paths: warning - absolute legacy roots: sessions" in result.stdout
+    assert str(tmp_path) not in result.stdout
+    assert "patient_db" not in result.stdout
+    assert "super-secret" not in result.stdout
+
+
+def test_doctor_human_config_error_is_actionable_and_redacted(monkeypatch, tmp_path):
+    cfg = tmp_path / "patient-private.yaml"
+    cfg.write_text("password: super-secret\nroots: [unterminated")
+    monkeypatch.setenv("THT_DATA_ROOT", str(tmp_path / "data"))
+
+    result = runner.invoke(app, ["doctor", "--config", str(cfg)])
+
+    assert result.exit_code == 1
+    assert "config: error - configuration is invalid or unreadable" in result.stdout
+    assert str(tmp_path) not in result.stdout
+    assert "super-secret" not in result.stdout
+    assert result.stderr == ""
diff --git a/harness/tests/test_portable_paths.py b/harness/tests/test_portable_paths.py
index b24f2b78..2f83fda3 100644
--- a/harness/tests/test_portable_paths.py
+++ b/harness/tests/test_portable_paths.py
@@ -57,6 +57,28 @@ def test_path_escape_is_rejected(tmp_path):
         resolve_workspace_paths(cfg_path, cfg, tmp_path / "data")
 
 
+def test_workspace_symlink_escape_is_rejected(tmp_path):
+    cfg_path = _write_config(tmp_path / "demo.yaml")
+    cfg = load_config(cfg_path)
+    data_root = tmp_path / "data"
+    (data_root / "workspaces").mkdir(parents=True)
+    (data_root / "workspaces" / "demo").symlink_to(tmp_path / "private", target_is_directory=True)
+
+    with pytest.raises(ConfigError, match="outside workspaces root"):
+        resolve_workspace_paths(cfg_path, cfg, data_root)
+
+
+def test_nested_root_symlink_escape_is_rejected(tmp_path):
+    cfg_path = _write_config(tmp_path / "demo.yaml")
+    cfg = load_config(cfg_path)
+    workspace = tmp_path / "data/workspaces/demo"
+    workspace.mkdir(parents=True)
+    (workspace / "sessions").symlink_to(tmp_path / "private", target_is_directory=True)
+
+    with pytest.raises(ConfigError, match="outside workspace root"):
+        resolve_workspace_paths(cfg_path, cfg, tmp_path / "data")
+
+
 def test_data_root_environment_activates_portable_paths(monkeypatch, tmp_path):
     cfg_path = _write_config(tmp_path / "demo.yaml")
     monkeypatch.setenv("THT_DATA_ROOT", str(tmp_path / "data"))
diff --git a/harness/tht/cli/doctor_cmd.py b/harness/tht/cli/doctor_cmd.py
index f97bf469..b1c44621 100644
--- a/harness/tht/cli/doctor_cmd.py
+++ b/harness/tht/cli/doctor_cmd.py
@@ -6,6 +6,7 @@ from pathlib import Path
 from typing import Any
 
 import typer
+import yaml
 
 from tht.cli.config_cmd import CONFIG_OPT
 from tht.config import ConfigError, load_config
@@ -17,7 +18,14 @@ def _emit(payload: dict[str, Any], as_json: bool) -> None:
         typer.echo(json.dumps(payload, sort_keys=True))
         return
     for component, result in payload["components"].items():
-        typer.echo(f"{component}: {result['status']}")
+        detail = ""
+        if result["status"] == "error":
+            detail = f" - {result['message']}"
+        elif component == "data_root" and result["status"] == "warning":
+            detail = " - set THT_DATA_ROOT to enable portable storage"
+        elif component == "workspace_paths" and result["status"] == "warning":
+            detail = " - absolute legacy roots: " + ", ".join(result["legacy_absolute"])
+        typer.echo(f"{component}: {result['status']}{detail}")
 
 
 def doctor(
@@ -32,11 +40,11 @@ def doctor(
     }
     try:
         cfg = load_config(config)
-    except ConfigError as exc:
-        path_error = "outside workspace root" in str(exc)
+    except (ConfigError, yaml.YAMLError, OSError) as exc:
+        path_error = isinstance(exc, ConfigError) and "outside workspace" in str(exc)
         target = "workspace_paths" if path_error else "config"
         # Validation errors can contain Pydantic input excerpts, including credentials.
-        message = str(exc) if path_error else "configuration is invalid"
+        message = str(exc) if path_error else "configuration is invalid or unreadable"
         components[target] = {"status": "error", "message": message}
         payload = {"ok": False, "components": components}
         _emit(payload, as_json)
diff --git a/harness/tht/paths.py b/harness/tht/paths.py
index 073c4ca9..51ea7b9d 100644
--- a/harness/tht/paths.py
+++ b/harness/tht/paths.py
@@ -39,7 +39,11 @@ def resolve_workspace_paths(
     Relative roots are sandboxed to the logical workspace. Absolute roots are a
     compatibility bridge for existing installations and are never rewritten.
     """
-    workspace = (data_root / "workspaces" / config_path.stem).resolve()
+    canonical_data_root = data_root.resolve()
+    workspaces_root = canonical_data_root / "workspaces"
+    workspace = (workspaces_root / config_path.stem).resolve()
+    if not workspace.is_relative_to(workspaces_root):
+        raise ConfigError("workspace resolves outside workspaces root")
     roots = cfg.roots
     return ResolvedPaths(
         workspace=workspace,