fix: second-audit gate findings (B1, I1-I8, M1-M10)

B1: gateway capability check now triggers on walking the sub2api
gateway, not on the gateway having filled a model; task-level
explicit models are audited (worker_capability_gateway_explicit)
but never blocked, preserving explicit priority; gateway-default
models still fail-fast under active.
I1: dry-run adds a gateway-model section, sourced only from
CLOUD_SUB2API_DEFAULT_MODEL (never queries the relay); an active
tier whose requires the gateway model fails or cannot verify
blocks, shadow only warns.
I2: shadow review gate now counts completed samples
(completed >= 20), same basis for sample_shortfall; the endpoint
attaches per-tier capability status (read-only policy load) and
flags capability-failing tiers in the recommendation.
I3: configured-but-broken routing policy logs a warning in
load_routing_policy (unconfigured stays silent); the worker sets
routing_policy_load_failed and audits
worker_routing_policy_load_failed per task.
I4: resume preamble wraps prior output/error as data with an
explicit do-not-execute constraint; position verified in run_one
(tree -> preamble -> project -> original) and the docs corrected
from the false 'closest to the original prompt' claim.
I5: decided model is written back with a CAS UPDATE
(model IS NULL OR model=''), so later attempts reuse it;
explicit models are never overwritten.
I6: agent_* columns added to worker._ensure_result_columns and
db.init_postgres_schema backfill; migrations backfills them for
tasks before insert (sender_task_id pattern); column-level tests
for agent_tool_approvals and task_attempts.
I7: coordinator requeue adds AND status=<snapshot> (rowcount 0
skips requeue/audit) and filters paused_by_user / user_cancel /
user_pause children, which are never revived or cleared.
I8: explicit-model tasks (including coordinator children that
inherited a parent model) audit a source=explicit worker_routing
row; evaluate_shadow counts it as per-tier explicit_n only,
never routed_n, never a dedup slot.
M1/M2/M3/M5/M6/M8/M10: dedup slot moved after tier validation,
shadow sort doc fixed, truncated recommendation notes truncation,
seed cleanup on gateway/quota/goal-cap early returns, tools-only
coordinator definitions rejected, preamble goal branch marked
effectively unreachable, DESIGN.md drift corrected (outside repo).
M4/M7/M9: documentation/new-field only (pass_rate_fully_measured,
whitespace-model shadow-drop note, bound-note race note); old
field semantics unchanged.

cloud/tests/test_p2_migrations.py

@@ -113,6 +113,24 @@ def _make_sqlite(path):
     conn.execute("INSERT INTO environments VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
                  ("e1", "p1", "dev", "main", "docker", "ready", "",
                   "https://example.invalid/r", "u1", 1.0, 1.0))
+    # Audit fix 3（I6）列级覆盖用：tasks 的 agent 列与
+    # task_attempts 整表，表级在清单里已有不算覆盖。
+    conn.execute("CREATE TABLE tasks(id TEXT PRIMARY KEY,"
+                 " project_id TEXT, agent_name TEXT,"
+                 " agent_version TEXT, agent_instructions TEXT,"
+                 " agent_tools TEXT, agent_tool_approvals TEXT)")
+    conn.execute("INSERT INTO tasks VALUES(?, ?, ?, ?, ?, ?, ?)",
+                 ("t1", "p1", "research-brief", "v1", "do x", "[]",
+                  '{"websearch": "ask"}'))
+    conn.execute("CREATE TABLE task_attempts(task_id TEXT,"
+                 " attempt_no INTEGER, kind TEXT,"
+                 " interrupted_reason TEXT, checkpoint_round INTEGER,"
+                 " result_text TEXT, error_text TEXT,"
+                 " created_at REAL,"
+                 " PRIMARY KEY(task_id, attempt_no))")
+    conn.execute("INSERT INTO task_attempts VALUES(?, ?, ?, ?, ?, ?, ?, ?)",
+                 ("t1", 1, "platform_fresh", "worker_shutdown", -1,
+                  "", "", 1.0))
     conn.commit()
     conn.close()
 
@@ -186,6 +204,42 @@ class TestMigrateNewTables(unittest.TestCase):
         self.assertEqual(len(fu_inserts), 1)
         self.assertIn("sender_task_id", fu_inserts[0])
 
+    def test_agent_columns_added_and_attempts_migrated(self):
+        # Audit fix 3（I6）：PG 侧 tasks 尚无 agent 列时，
+        # 迁移必须先 ALTER 补齐 5 列再直插；task_attempts
+        # 行必须按列原样迁过去（表级在清单里不算列级覆盖）。
+        with tempfile.TemporaryDirectory() as tmp:
+            src = os.path.join(tmp, "src.db")
+            _make_sqlite(src)
+            fake = FakePgConn(pragma_columns={
+                "projects": {"repo_url"},
+                "tasks": {"id", "project_id"},
+                "task_followups": {"id", "task_id", "project_id",
+                                   "body", "mode", "status",
+                                   "created_by", "sender_task_id",
+                                   "created_at", "updated_at"},
+            })
+            result = migrate_sqlite_to_postgres(src, pg_conn=fake)
+        self.assertEqual(result.get("tasks"), 1, "tasks")
+        self.assertEqual(result.get("task_attempts"), 1, "task_attempts")
+        for col in ("agent_name", "agent_version",
+                    "agent_instructions", "agent_tools",
+                    "agent_tool_approvals"):
+            self.assertTrue(
+                any("tasks" in a and col in a for a in fake.alters),
+                "未发出 tasks.%s 补列 ALTER：%s" % (col, fake.alters))
+        tasks_inserts = [cols for t, cols in fake.inserts
+                         if t == "tasks"]
+        self.assertEqual(len(tasks_inserts), 1)
+        self.assertIn("agent_tool_approvals", tasks_inserts[0])
+        attempts_inserts = [cols for t, cols in fake.inserts
+                            if t == "task_attempts"]
+        self.assertEqual(len(attempts_inserts), 1)
+        for col in ("task_id", "attempt_no", "kind",
+                    "interrupted_reason", "checkpoint_round",
+                    "result_text", "error_text", "created_at"):
+            self.assertIn(col, attempts_inserts[0])
+
     def test_sender_column_present_skips_alter(self):
         with tempfile.TemporaryDirectory() as tmp:
             src = os.path.join(tmp, "src.db")