diff --git a/doc/plans/2026-10-12-test-audit-r10-db.md b/doc/plans/2026-10-12-test-audit-r10-db.md
new file mode 100644
index 00000000000..8dd3aaf25a2
--- /dev/null
+++ b/doc/plans/2026-10-12-test-audit-r10-db.md
@@ -0,0 +1,30 @@
+# Round 10 database schema test audit
+
+This test-only change is stacked on #16075 at `3432307f95f679e20b991c6a250934c2114b7aaf`. The original matched baseline and control ran on its prior head `e86a747fc028069d2bb4d699bd814e0d82fad558`. The parent correction changes documentation only; the rebased complete owner replay passed 6/6 with no failures or skips. It removes one registered case and six net test lines. It makes no measured CI time claim.
+
+| Retired case | Keeper | Preserved observations |
+| --- | --- | --- |
+| `keeps the owner principal non-null and drops the environment from the key` | `serializes the active slot on company, owner, and adapter` | Copy the exact `started_by_user_id` non-null assertion. The keeper's exact index column list already proves that the owner is present and the environment is absent. |
+
+Both cases inspect the same `adapterAuthSessions` table and active index. The keeper still checks index presence, uniqueness, the exact company/owner/adapter columns, and the partial predicate. The public-session identity, claim marker, active states, secret-column exclusion, and migration SQL cases remain separate. No fixture, helper, schema, migration, or caller changes.
+
+The direct owner is `packages/db/src/schema/adapter_auth_sessions.ts`. Its owner column prevents a null principal from escaping the active unique index. Local login, device login, and setup-token services use this company/owner/adapter scope. The DB project runs in the default `general-workspaces-c` CI group.
+
+Complete-file command:
+
+```sh
+pnpm exec vitest run packages/db/src/adapter-auth-sessions-schema.test.ts
+```
+
+| Run on the exact stacked base | Passed | Failed | Skipped |
+| --- | ---: | ---: | ---: |
+| Baseline | 7 | 0 | 0 |
+| Candidate | 6 | 0 | 0 |
+| Nullability control | 5 | 1 | 0 |
+| Restored-owner candidate | 6 | 0 | 0 |
+
+The deliberate control removes only `.notNull()` from `startedByUserId` in the production schema. The complete file fails only the keeper at the copied non-null assertion (`false` instead of `true`). The other five cases pass. Restore the schema before the positive replay.
+
+A whole-program byte comparison proves that the only test changes are one retired statement and one exact copied assertion. Production schema bytes are restored with SHA-256 `ada8f01da2171306b97e5cb2b14b52dd53f6a7d58dd9dd51414d381c56821235`. Candidate test SHA-256 is `9719104e3f6d79d868dee36b1778ce758da8829ffc4485019cad41a128bcff6f`. The earlier independent proof at `77408fa6c3d7c916d7160760eae2144aaa0f8fe7` is preserved separately. Root review approved the keeper map before this PR.
+
+Risk: the index keeper now reports both index and owner-nullability defects. An earlier index failure can stop the later assertion, but still fails the scenario. Each distinct schema and migration contract remains covered.
diff --git a/packages/db/src/adapter-auth-sessions-schema.test.ts b/packages/db/src/adapter-auth-sessions-schema.test.ts
index d0375816757..d55c56b69fb 100644
--- a/packages/db/src/adapter-auth-sessions-schema.test.ts
+++ b/packages/db/src/adapter-auth-sessions-schema.test.ts
@@ -54,13 +54,7 @@ describe("adapter auth sessions schema", () => {
     ]);
     // The active index is partial; the where clause is present.
     expect(active?.config.where).toBeDefined();
-  });
-
-  it("keeps the owner principal non-null and drops the environment from the key", () => {
     expect(columnIsNotNull(adapterAuthSessions, "started_by_user_id")).toBe(true);
-    const activeColumns = indexColumns(adapterAuthSessions, ACTIVE_INDEX);
-    expect(activeColumns).toContain("started_by_user_id");
-    expect(activeColumns).not.toContain("environment_id");
   });
 
   it("adds the public session id, non-null and unique", () => {