# Feature Demo: F003 — Dense Reward System

> **Generated:** 2026-03-28T06:07:34Z
> **Context source:** spec + discovery only (implementation not read)
> **Feature entry:** [FEATURES.json #F003](FEATURES.json)

---

## What This Feature Does

Before this feature, agents only got a binary reward at the end of an episode, which made exploration hard to learn from. With F003, agents now get small, meaningful reward signals during non-terminal DESCRIBE/SAMPLE/QUERY steps, plus the final terminal correctness reward.

From the user perspective, this means random exploration should produce low cumulative reward, targeted exploration should produce higher reward, and anti-gaming controls should prevent farming rewards via repeated or low-value behavior.

---

## What Is Already Proven

### Verified in This Demo Run

- Happy-path SQL exploration smoke flow passes locally.
- Non-SELECT query error handling passes locally.
- Budget-exhaustion terminal reward behavior passes locally.
- Clamp boundary unit tests for step-reward floor/ceiling pass locally.
- Full smoke suite passes locally (25/25).

### Previously Verified Evidence

- `specs/FEATURES.json` records verifier-approved evidence for F003: `uv run --with pytest pytest tests/ -v` with `166 passed`.
- `specs/F003-IMPLEMENTATION_SPEC.md` (Section 7, Step 3.2) records final verification evidence and verifier approval.
- `specs/F003-VERIFICATION_SPEC.md` defines unit/integration/e2e scenarios and edge-case checklist used for this demo plan.

---

## What Still Needs User Verification

- Run a real episode manually (`reset` → `DESCRIBE/SAMPLE/QUERY/ANSWER`) and inspect live `observation.reward` progression across steps.
- Confirm training-facing calibration in your own workload (random exploration ~0.1, targeted ~0.3, correct answer total ~1.3) under your runtime conditions.

---

## Quickstart / Verification Steps

> Run these commands to see the feature in action:

```bash
uv run --with pytest pytest tests/test_smoke.py -v -k "sample_and_query_success"
uv run --with pytest pytest tests/test_smoke.py -v -k "query_rejects_non_select"
uv run --with pytest pytest tests/unit/test_reward.py -v -k "compute_reward_clamp_upper or compute_reward_clamp_lower"
```

No extra setup was needed in this environment beyond project dependencies.

---

## Live Local Proof

> This feature is internal server-side reward logic (no direct end-user CLI command for reward computation itself), so strongest truthful local proof is targeted runtime smoke/unit execution.

### Run a happy-path exploration step flow

This validates a representative non-terminal exploration path.

```bash
uv run --with pytest pytest tests/test_smoke.py -v -k "sample_and_query_success"
```

```text
============================= test session starts ==============================
platform darwin -- Python 3.12.3, pytest-9.0.2, pluggy-1.6.0 -- /Users/hjerp/.cache/uv/builds-v0/.tmpjnSgOs/bin/python
cachedir: .pytest_cache
rootdir: /Users/hjerp/Projects/sql-env-F003-dense-reward-system
configfile: pyproject.toml
plugins: anyio-4.13.0
collecting ... collected 25 items / 24 deselected / 1 selected

tests/test_smoke.py::TestEnvironment::test_sample_and_query_success PASSED [100%]

======================= 1 passed, 24 deselected in 3.79s =======================
```

Notice the targeted flow test passes, showing exploration/query behavior remains valid under dense reward integration.

### Verify boundary clamping behavior

This checks upper/lower clamp boundaries for cumulative step rewards.

```bash
uv run --with pytest pytest tests/unit/test_reward.py -v -k "compute_reward_clamp_upper or compute_reward_clamp_lower"
```

```text
============================= test session starts ==============================
platform darwin -- Python 3.12.3, pytest-9.0.2, pluggy-1.6.0 -- /Users/hjerp/.cache/uv/builds-v0/.tmp91LChv/bin/python
cachedir: .pytest_cache
rootdir: /Users/hjerp/Projects/sql-env-F003-dense-reward-system
configfile: pyproject.toml
plugins: anyio-4.13.0
collecting ... collected 66 items / 64 deselected / 2 selected

tests/unit/test_reward.py::TestComputeStepReward::test_compute_reward_clamp_upper PASSED [ 50%]
tests/unit/test_reward.py::TestComputeStepReward::test_compute_reward_clamp_lower PASSED [100%]

======================= 2 passed, 64 deselected in 4.58s =======================
```

This confirms reward accumulation boundaries are enforced at both extremes.

---

## Existing Evidence

- `specs/F003-IMPLEMENTATION_SPEC.md` Section 7 includes recorded per-slice evidence for Layer 1, Layer 2, integration wiring, and full-suite verification.
- `specs/FEATURES.json` includes approved verification evidence (`tests_run: 166`, `tests_passed: 166`).

---

## Manual Verification Checklist

1. Start a fresh episode and run one `DESCRIBE` action.
2. Run at least two distinct `QUERY` actions, then repeat one exact query.
3. Confirm repeat behavior is less rewarding than first-time useful queries.
4. Submit an invalid/non-SELECT query and confirm safe penalty behavior.
5. End with `ANSWER` and verify terminal reward still follows correctness outcome.

---

## Edge Cases Exercised

### Invalid non-SELECT query is safely handled

```bash
uv run --with pytest pytest tests/test_smoke.py -v -k "query_rejects_non_select"
```

```text
============================= test session starts ==============================
platform darwin -- Python 3.12.3, pytest-9.0.2, pluggy-1.6.0 -- /Users/hjerp/.cache/uv/builds-v0/.tmpitwmJ8/bin/python
cachedir: .pytest_cache
rootdir: /Users/hjerp/Projects/sql-env-F003-dense-reward-system
configfile: pyproject.toml
plugins: anyio-4.13.0
collecting ... collected 25 items / 24 deselected / 1 selected

tests/test_smoke.py::TestEnvironment::test_query_rejects_non_select PASSED [100%]

======================= 1 passed, 24 deselected in 4.04s =======================
```

This matters because SQL errors/unsafe query patterns should not break reward flow.

### Budget exhaustion keeps terminal reward contract

```bash
uv run --with pytest pytest tests/test_smoke.py -v -k "budget_exhaustion_sets_done_and_zero_reward"
```

```text
============================= test session starts ==============================
platform darwin -- Python 3.12.3, pytest-9.0.2, pluggy-1.6.0 -- /Users/hjerp/.cache/uv/builds-v0/.tmpRB9qch/bin/python
cachedir: .pytest_cache
rootdir: /Users/hjerp/Projects/sql-env-F003-dense-reward-system
configfile: pyproject.toml
plugins: anyio-4.13.0
collecting ... collected 25 items / 24 deselected / 1 selected

tests/test_smoke.py::TestEnvironment::test_budget_exhaustion_sets_done_and_zero_reward PASSED [100%]

======================= 1 passed, 24 deselected in 3.89s =======================
```

This matters because dense shaping must not corrupt terminal episode semantics.

---

## Test Evidence (Optional)

> Supplementary proof that the feature works correctly across broader scenarios.

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

Representative command:

```bash
uv run --with pytest pytest tests/test_smoke.py -v
```

```text
[... full smoke output ...]
============================== 25 passed in 3.67s ==============================
```

---

## Feature Links

- Implementation spec: `specs/F003-IMPLEMENTATION_SPEC.md`
- Verification spec: `specs/F003-VERIFICATION_SPEC.md`

---

*Demo generated by `feature-demo` agent. Re-run with `/feature-demo F003` to refresh.*