ai: apply changes for #870 (2 review threads)

Addresses:
  - #3600996714 at .github/workflows/engineer-bot.yml:200
  - #3601002346 at CONTRIBUTING.md:156

Signed-off-by: peco-engineer-bot[bot] <peco-engineer-bot[bot]@users.noreply.github.com>

Author: peco-engineer-bot[bot]

.bot/prompts/engineer/system.md

@@ -89,6 +89,14 @@ selection than a single `-k` test — a whole file, or `tests/unit` — append
 the same `--all-extras` install). Skipping this produces a confusing false red
 that has nothing to do with your fix.
 
+**Only the `default` schema is provisioned for this job.** The e2e connection env
+sets `DATABRICKS_SCHEMA` implicitly to `"default"` (it is intentionally left
+unset, mirroring `code-coverage.yml`, so the `schema` fixture falls back to
+`"default"`). Write your repro against the `default` schema — do NOT assume a
+seeded/non-default schema (e.g. staging-ingestion / UC-volume style tests, which
+also require `ingestion_user`), or the test will confusingly fail on a missing
+schema rather than on the bug.
+
 **Always `-k`-filter to your own test** — do NOT run the whole `tests/e2e` suite:
 this job provides a live connection but does not seed the full per-run fixture set
 the broader suite expects, so unrelated E2E tests would fail or skip and that noise

CONTRIBUTING.md

@@ -146,22 +146,21 @@ The suites marked `[not documented]` require additional configuration which will
 
 #### Backends and test tiers
 
-The connector has **three execution backends**, selected per connection. When you
+The connector has **two execution backends**, selected per connection. When you
 reproduce or fix a bug, use the backend the bug is actually on — a Thrift bug won't
 reproduce on a kernel connection, and vice versa:
 
 | Backend | Select via (connect kwarg / `extra_params`) | Where its tests live |
 | --- | --- | --- |
 | **Thrift** (default) | *(nothing — the default path)* | the general `tests/e2e` suite (the `{}` parametrize case) and mocked `tests/unit` |
-| **SEA** | `use_sea=True` | the general `tests/e2e` suite (the `{"use_sea": True}` parametrize case) |
 | **Kernel** (Rust, optional) | `use_kernel=True` | the dedicated `tests/e2e/test_kernel_backend.py` / `test_kernel_tls.py`, plus the offline routing test `tests/unit/test_session.py -m realkernel` |
 
 Notes that matter when running the suite:
 
 - **Kernel is an opt-in extra**, not part of the default install. `use_kernel=True`
   needs `pip install "databricks-sql-connector[kernel]"` (or `poetry install
   --all-extras`); without it the connector raises a clear "install the `[kernel]`
-  extra" error. Most bugs are on the **Thrift/SEA** path — reproduce those there;
+  extra" error. Most bugs are on the **Thrift** path — reproduce those there;
   only reach for kernel when the issue is specifically about `use_kernel`.
 - **`realkernel` tests must run in their own pytest invocation.** When the real
   kernel wheel is installed (`--all-extras`), several unit tests fake