# Feature Demo: F001 — Core Environment Loop

> **Generated:** 2026-03-24T21:36:32Z
> **Context source:** spec + discovery only (implementation not read)
> **Feature entry:** [FEATURES.json (F001)](./FEATURES.json)

---

## What This Feature Does

F001 turns the SQL environment from a non-functional loop into a usable episode flow: an agent can reset into a question, explore schema/data with structured actions, run SQL safely, and terminate with an answer or budget exhaustion.

From a user perspective, this should feel predictable and teachable: fast query feedback, clear errors when a query/action is invalid, and clean episode boundaries.

---

## What Is Already Proven

### Verified in This Demo Run

- Server startup works locally via `uv run uvicorn server.app:app --host 127.0.0.1 --port 8011` (startup/shutdown logs captured).
- The environment currently fails at `/reset` in this workspace because the required Spider DB file is missing (`FileNotFoundError` for `student_assessment`).
- Downloader CLI is present and runnable (`--help` works).
- Downloader input hardening rejects unsafe DB identifiers (e.g. `../bad`).
- Full local test suite passes (`25 passed`).

### Previously Verified Evidence

- `specs/FEATURES.json` (`features[].id == F001`) records verification evidence: `uv run pytest tests/ -v`, 25/25 passed, verifier `approved` at `2026-03-24T21:27:31Z`.
- `specs/F001-IMPLEMENTATION_SPEC.md` Section 10 states user-value behavior for reset/step lifecycle and structured actions.

---

## What Still Needs User Verification

- Provision `data/databases/student_assessment/student_assessment.sqlite` successfully in your environment.
- Re-run live `/reset` and `/step` API calls after DB provisioning to confirm end-to-end episode behavior (DESCRIBE/SAMPLE/QUERY/ANSWER).

---

## Quickstart / Verification Steps

> Run these commands to see the feature in action:

```bash
uv run uvicorn server.app:app --host 127.0.0.1 --port 8011
uv run python scripts/download_spider_databases.py --db-id student_assessment
uv run pytest tests/ -v
```

If `/reset` fails with missing DB, complete the DB download/provisioning first, then retry API interactions.

---

## Live Local Proof

### Start the Environment Server

This confirms the feature surface is exposed on a local API endpoint.

```bash
uv run uvicorn server.app:app --host 127.0.0.1 --port 8011
```

```text
INFO:     Started server process [26402]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://127.0.0.1:8011 (Press CTRL+C to quit)
INFO:     Shutting down
INFO:     Waiting for application shutdown.
INFO:     Application shutdown complete.
INFO:     Finished server process [26402]

<bash_metadata>
bash tool terminated command after exceeding timeout 8000 ms
</bash_metadata>
```

The API process starts successfully and advertises the expected local URL.

### Attempt Reset Without Database Provisioning (Proof Boundary)

This shows the current environment boundary in this workspace: reset cannot complete until DB assets are present.

```bash
uv run python - <<'PY'
import httpx
from server.app import app

transport = httpx.ASGITransport(app=app)

async def main():
    async with httpx.AsyncClient(transport=transport, base_url="http://local") as client:
        try:
            await client.post('/reset', json={})
        except Exception as exc:
            print(type(exc).__name__)
            print(str(exc))

import asyncio
asyncio.run(main())
PY
```

```text
Loaded tokenizer: mistralai/Mistral-7B-Instruct-v0.1
FileNotFoundError
Database 'student_assessment' not found in /Users/hjerp/Projects/sql-env-F001-core-environment-loop/data/databases
```

The failure is explicit and actionable (missing DB), not a crash or opaque error.

---

## Existing Evidence

- Verification record source: `specs/FEATURES.json` → `features[F001].verification_evidence`.
- Verification spec source: `specs/F001-VERIFICATION_SPEC.md` (unit/integration/API/E2E scenarios and edge-case checklist).

---

## Manual Verification Checklist

1. Download/provision Spider DB files so `student_assessment.sqlite` exists under `data/databases/student_assessment/`.
2. Start server: `uv run uvicorn server.app:app --host 127.0.0.1 --port 8011`.
3. POST `/reset` and confirm `done=false`, question present, and schema table names visible.
4. POST `/step` with `DESCRIBE` and `QUERY` actions; confirm step/budget updates and readable results.
5. POST invalid `QUERY` (non-SELECT) and verify clear error in observation.
6. POST `ANSWER` and verify terminal `done=true` with reward behavior.

---

## Edge Cases Exercised

### Unsafe Database Identifier Rejected

```bash
uv run python scripts/download_spider_databases.py --db-id "../bad"
```

```text
ValueError: Invalid db_id. Only letters, numbers, and underscores are allowed.
```

This confirms input hardening against path-traversal style DB IDs.

### Upstream Database URL Failure Is Surfaced Clearly

```bash
uv run python scripts/download_spider_databases.py --db-id student_assessment
```

```text
RuntimeError: Failed to download 'student_assessment' from Spider raw URL: HTTP Error 404: Not Found
```

This demonstrates an explicit failure mode for data provisioning when upstream URL resolution fails.

---

## Test Evidence (Optional)

> Supplementary proof that the feature works correctly across scenarios.

| Test Suite | Tests | Status |
|---|---|---|
| Smoke / contract regression (`tests/test_smoke.py`) | 25 | All passed |

Representative command:

```bash
uv run pytest tests/ -v
```

```text
============================= test session starts ==============================
...
collected 25 items
...
============================== 25 passed in 6.27s ==============================
```

---

## Feature Links

- Implementation spec: `specs/F001-IMPLEMENTATION_SPEC.md`
- Verification spec: `specs/F001-VERIFICATION_SPEC.md`

---

*Demo generated by `feature-demo` agent. Re-run with `/feature-demo F001` to refresh.*