diff --git a/.github/workflows/quality-gate.yml b/.github/workflows/quality-gate.yml
index 9a8cf79..821ae9a 100644
--- a/.github/workflows/quality-gate.yml
+++ b/.github/workflows/quality-gate.yml
@@ -158,7 +158,11 @@ jobs:
       # Prints a final block accounting for every test: PASSED / FAILED /
       # ERROR / SKIPPED (with reasons) / NOT RUN (deselected). --strict fails
       # the build on any skip.
+      # The API reads PGDATABASE (api/config.py). The schema lives in
+      # te_mgmt_dev, not the job-level default "postgres" (issue #45).
       - name: Full test suite — final result with skip accounting
+        env:
+          PGDATABASE: te_mgmt_dev
         run: python3 scripts/test_report.py --strict
 
       - name: Upload eval reports
diff --git a/evals/runner.py b/evals/runner.py
index c191a49..5a9c0a0 100644
--- a/evals/runner.py
+++ b/evals/runner.py
@@ -596,8 +596,9 @@ def _column_signature(db: str, schema: str) -> Dict[str, List[str]]:
     different namespaces compare equal when their structure matches.
     """
     # The schema name is bound by psql via --set + :'sch' rather than pasted into
-    # the SQL text, so there is no string interpolation to reason about even
-    # though the value comes from the ENV_TARGETS constant.
+    # the SQL text. psql only interpolates variables in SQL it reads from a file
+    # or stdin, never in -c, so the query goes on stdin (issue #45: under -c it
+    # was a syntax error that this function used to report as "0 tables").
     query = (
         "SELECT table_name, column_name, data_type, is_nullable "
         "FROM information_schema.columns "
@@ -605,11 +606,12 @@ def _column_signature(db: str, schema: str) -> Dict[str, List[str]]:
         "ORDER BY table_name, ordinal_position"
     )
     r = subprocess.run(
-        ["psql", "-tA", "-d", db, "--set=sch=" + schema, "-c", query],
-        env=_pg_env(), capture_output=True, text=True, timeout=30,
+        ["psql", "-tA", "-v", "ON_ERROR_STOP=1", "-d", db, "--set=sch=" + schema],
+        input=query, env=_pg_env(), capture_output=True, text=True, timeout=30,
     )
     if r.returncode != 0:
-        return {}
+        raise RuntimeError("schema query on " + db + "." + schema + " failed: "
+                           + r.stderr.strip()[-300:])
     sig: Dict[str, List[str]] = {}
     for line in r.stdout.splitlines():
         parts = line.split("|")
@@ -689,8 +691,13 @@ def _run_envs_have_identical_structure(
 
     deploys = [_deploy_env(env_name) for env_name, _, _ in targets]
     signatures: Dict[str, Dict[str, List[str]]] = {}
+    query_errors: List[str] = []
     for env_name, db, schema in targets:
-        signatures[env_name] = _column_signature(db, schema)
+        try:
+            signatures[env_name] = _column_signature(db, schema)
+        except RuntimeError as exc:
+            signatures[env_name] = {}
+            query_errors.append("env " + env_name + ": " + str(exc))
 
     table_counts = {e: len(sig) for e, sig in signatures.items()}
     result.actual = {
@@ -698,7 +705,8 @@ def _run_envs_have_identical_structure(
         "table_counts": table_counts,
     }
 
-    errors: List[str] = []
+    # A failed query is not an empty schema; report it as what it is.
+    errors: List[str] = list(query_errors)
 
     if exp.get("all_envs_deploy_exit_zero") is True:
         for d in deploys:
diff --git a/tests/run_all_tests.sql b/tests/run_all_tests.sql
index 8dd4034..abec3d9 100644
--- a/tests/run_all_tests.sql
+++ b/tests/run_all_tests.sql
@@ -32,11 +32,17 @@
 
 -- ── Step 1: Load the test framework (results table + assertion functions) ─────
 
--- Set search_path so framework objects and assertions resolve without schema prefix.
+-- The harness keeps its own objects (test_run_results, assert_*, report_*) in
+-- te_test_harness so they never land in the schema under test, where Tier E
+-- would see them as drift (issue #45). It comes first on search_path, so the
+-- framework's unqualified CREATEs go there; T&E tables still resolve unqualified
+-- from the env schema, and the suites address it via te.schema_name anyway.
+CREATE SCHEMA IF NOT EXISTS te_test_harness;
+
 -- Expose per-env vars via current_setting() for PL/pgSQL DO blocks (:'var' doesn't
 -- substitute inside $dollar-quoted$ strings in psql 18).
 SELECT
-   set_config('search_path',    :'schema_name' || ',public', false),
+   set_config('search_path',    'te_test_harness,' || :'schema_name' || ',public', false),
    set_config('te.schema_name', :'schema_name',              false),
    set_config('te.app_user',    :'app_user',                 false),
    set_config('te.conn_limit',  :'conn_limit',               false);
@@ -70,7 +76,7 @@ SELECT
    skipped,
    pass_rate,
    suite_status
-FROM :"schema_name".report_suite_summary();
+FROM te_test_harness.report_suite_summary();
 
 \echo ''
 \echo '============================================================'
@@ -83,7 +89,7 @@ SELECT
    expected,
    actual,
    message
-FROM :"schema_name".report_failures();
+FROM te_test_harness.report_failures();
 
 \echo ''
 \echo '============================================================'
@@ -97,7 +103,7 @@ SELECT
    expected,
    actual,
    message
-FROM :"schema_name".report_detail();
+FROM te_test_harness.report_detail();
 
 \echo ''
 \echo '============================================================'
@@ -111,7 +117,7 @@ SELECT
    skipped,
    pass_rate,
    overall
-FROM :"schema_name".report_totals();
+FROM te_test_harness.report_totals();
 
 \echo ''
 \echo '============================================================'
diff --git a/tests/test_evals_tier_e_x.py b/tests/test_evals_tier_e_x.py
index 1088f84..51efa99 100644
--- a/tests/test_evals_tier_e_x.py
+++ b/tests/test_evals_tier_e_x.py
@@ -9,8 +9,10 @@
 
 from __future__ import annotations
 
+import subprocess
 import sys
 import unittest
+from unittest.mock import patch
 from pathlib import Path
 
 import pytest
@@ -83,6 +85,47 @@ def test_env_targets_cover_all_four_environments(self):
         self.assertEqual(len({e[2] for e in runner.ENV_TARGETS}), 4)
 
 
+@pytest.mark.unit
+class TierEColumnSignatureQuery(unittest.TestCase):
+    """Issue #45: the schema query itself, not just the comparison.
+
+    psql never interpolates :'var' inside -c, so the query must go on stdin, and
+    a failed query must not be reported as an empty schema.
+    """
+
+    def _scenario(self, completed):
+        expected = {"expected": {"min_tables_per_env": 12},
+                    "envs_under_test": ["dev"]}
+        result = runner.ScenarioResult(tier="e", name="t")
+        with patch.object(runner, "_deploy_env",
+                          return_value={"env": "dev", "exit_code": 0}), \
+             patch.object(runner.subprocess, "run", return_value=completed) as run:
+            runner._run_envs_have_identical_structure(result, expected)
+        return result, run
+
+    def test_query_is_sent_on_stdin_not_via_dash_c(self):
+        ok = subprocess.CompletedProcess([], 0, stdout="t|c|text|NO\n", stderr="")
+        _, run = self._scenario(ok)
+        args, kwargs = run.call_args
+        self.assertNotIn("-c", args[0])
+        self.assertIn(":'sch'", kwargs["input"])
+
+    def test_query_failure_is_reported_as_a_query_error(self):
+        bad = subprocess.CompletedProcess([], 1, stdout="",
+                                          stderr='ERROR:  syntax error at or near ":"')
+        result, _ = self._scenario(bad)
+        self.assertFalse(result.passed)
+        self.assertTrue(any("schema query" in e and "syntax error" in e
+                            for e in result.errors), result.errors)
+
+    def test_genuinely_empty_schema_still_fails(self):
+        empty = subprocess.CompletedProcess([], 0, stdout="", stderr="")
+        result, _ = self._scenario(empty)
+        self.assertFalse(result.passed)
+        self.assertIn("env dev has 0 tables in its schema, expected >= 12 "
+                      "(deploy may have partially failed)", result.errors)
+
+
 @pytest.mark.unit
 class TierXSqliteStructure(unittest.TestCase):
     """O-08: SQLite DDL execution and structural readback."""