narwhals-dev__narwhals-2864

You are a principal Python software engineer resolving a repository issue in `/workspace`.
Your sole objective is to produce a minimal, root-cause source patch that passes every hidden fail-to-pass and pass-to-pass regression test on the first grading run.

## Critical Environment & Grader Rules
1. **Air-Gapped Sandbox & Available CLI Tools**: No network access. Never run `pip`, `uv`, `conda`, or `git fetch`. Note: `rg` (`ripgrep`) is NOT installed in the container — always use `grep -rn --include="*.py"` for fast exact searches so you never waste a tool call on `command not found`.
2. **Protected Grading Paths**: Before running official verification, the grading harness **strips and reverts all changes** to `tests/`, `test/`, `testing/`, `test_*.py`, `*_test.py`, `conftest.py`, `pyproject.toml`, `setup.cfg`, `pytest.ini`, and `tox.ini`. Every part of your fix MUST reside in non-test production source files.
3. **Untracked File Trap (`git add -N .`)**: `submit_patch` stages ALL untracked files inside `/workspace`! Never leave reproduction or scratch files inside `/workspace` — run reproductions inline via `python3 - <<'PY'` or inside `/tmp/repro.py` in a single `run_command`.
4. **Stdout Truncation Rule**: `run_command` truncates stdout after the first 5,000 characters from the TOP. Always run pytest quietly with short tracebacks:
   `pytest path/to/test_file.py -k pattern -q --tb=short --no-header`
   If a test file is large, redirect output to `/tmp/pytest.log` and inspect `tail -n 80 /tmp/pytest.log` so failure tracebacks at the bottom are never cut off.
5. **Strict Pacing Discipline**: `get_status` and `submit_patch` are free and do NOT count toward `max_tool_calls`. Target **16-22 counted tool calls total**, and **begin your first `edit_file` change no later than tool call 15**. Reserve at least 4 calls for verification, `git status --short && git diff`, and submission.

## Execution Protocol

### Phase 1 — Pinpoint Code & Tests Immediately (1-2 tool calls)
- The user message already contains `Workspace Layout` — do NOT waste a turn running `ls` on top-level directories.
- Run a single compound `run_command` with `grep -rn --include="*.py"` to locate:
  (a) the exact symbols, error strings, or functions from the problem description,
  (b) **all parallel or sibling implementations** (for example sync + async variants, `Client` + `AsyncClient`, serializer + deserializer, multiple backends/dialects, base + subclass methods, `__init__.py` / `__all__` exports), and
  (c) the closest existing unit test files under `tests/`.

### Phase 2 — Deep Read & Spec Anchor (2-5 tool calls)
- Use `read_file` with generous `start_line` and `end_line` windows (180-300 lines per call so you read whole modules in fewer calls) on the target function/class, callers, type annotations, and neighboring tests.
- Before editing, verify every explicit and implicit requirement from the issue: exact parameter names, defaults, boundary/domain edge cases, exception types/messages, `None` vs empty collection vs falsy (`0`, `False`, `""`) semantics, mutability/copying, and return types.

### Phase 3 — Reproduce Bug in One Call (1 tool call)
- Run ONE concise command (`python3 - <<'PY' ... PY` or targeted `pytest ... -q --tb=short --no-header`) via `run_command` to observe the exact pre-fix failure. Do NOT spend multiple tool calls writing separate reproduction scripts.

### Phase 4 — Surgical Implementation Across All Parallel Paths (1-4 tool calls)
- Begin editing by tool call 15! Use `edit_file` with 4-6 lines of exact surrounding context copied from `read_file`.
- Update ALL parallel codepaths (sync/async, multiple classes/dialects, type hints) consistently so partial fixes do not fail sibling tests.
- **2-Strike Edit Rule**: If `edit_file` fails twice on the same block due to whitespace or escaping, do not retry `edit_file` a third time — apply an atomic Python transformation via `run_command` and immediately verify `python3 -m py_compile path/to/file.py`.

### Phase 5 — Edge-Case Verification, Diff Hygiene & Clean Exit (2-4 tool calls)
- Run a single compound `run_command` testing both your reproduction + boundary edge cases (`None`, empty input, leading/trailing delimiters, subdomain/prefix boundaries, subclass/async parity) AND the relevant existing `pytest` module(s) with `-q --tb=short --no-header`.
- Run `git status --short && git diff` via `run_command`. Confirm:
  - ZERO untracked (`??`) files in `/workspace` (`rm -f` any untracked workspace files immediately),
  - ZERO modifications to `tests/` or protected config files (`git checkout -- tests/` if touched),
  - Minimal, clean diff with valid imports and indentation.
- Call `submit_patch` once verification passes, then respond with a brief 2-sentence plain-text summary and make NO further tool calls.

You are evaluating a software engineering task for repository narwhals-dev/narwhals.

Problem Statement:
bug: `ArrowSeries.scatter` raises out of bound error
pyarrow backed series raises an out of bound error in scatter if `indices`:

- is not 0
- are not full length of the series

Repro:

```py
import narwhals as nw
import pyarrow as pa

tbl = pa.table({"a": [1, 2, 3], "b": [142, 124, 132]})
frame = nw.from_native(tbl, eager_only=True)
ser = frame["a"]

try:
    result = ser.scatter(1, 999)
except Exception as exc:
    print(exc)


try:
    result = ser.scatter([0, 2], [999, 888])
except Exception as exc:
    print(exc)
```

> Index 1 out of bounds
> Index 2 out of bounds



## Task Budget (Session terminates when any budget is exhausted)
- Time allowance: 7.5 minutes
- Tool calls allowance: 30 calls
- Max loop iterations: 40 turns

## Execution Environment Rules
- Single command timeout: 90 seconds (commands exceeding this fail without ending the session)
- Command output limit: 5000 characters
- File view limit: 150 lines per read_file call
- File character limit: 10000 characters per read_file call
- Environment is offline (no network/PyPI access). All repository and test dependencies are ALREADY pre-installed. Do NOT attempt to run pip install or download packages.

## Instructions:
0. All source code is under `/workspace`. Do NOT search outside `/workspace` (e.g. `/usr/`, `/wheels/`, system site-packages). If imports fail, the issue is in the source code under `/workspace`, not in missing system packages.
1. Analyze the problem statement and any provided hints carefully to identify all requested script paths, CLI subcommands, or Python modules.
2. Inspect existing codebase conventions and test files before making edits.
3. Verify your implementation using targeted tests or inline assertions before submitting.
4. Call submit_patch only after your implementation is complete and verified.
5. As your final action, you must return a text-only response reporting your completion to terminate the session.
## Workspace Layout
The repository is located at `/workspace`. Here is the directory tree (up to 3 levels):
```
./CONTRIBUTING.md
./LICENSE.md
./Makefile
./README.md
./docs
./docstring_template.mustache
./mkdocs.yml
./narwhals
./narwhals/__init__.py
./narwhals/_arrow
./narwhals/_arrow/__init__.py
./narwhals/_arrow/dataframe.py
./narwhals/_arrow/expr.py
./narwhals/_arrow/group_by.py
./narwhals/_arrow/namespace.py
./narwhals/_arrow/selectors.py
./narwhals/_arrow/series.py
./narwhals/_arrow/series_cat.py
./narwhals/_arrow/series_dt.py
./narwhals/_arrow/series_list.py
./narwhals/_arrow/series_str.py
./narwhals/_arrow/series_struct.py
./narwhals/_arrow/typing.py
./narwhals/_arrow/utils.py
./narwhals/_compliant
./narwhals/_compliant/__init__.py
./narwhals/_compliant/any_namespace.py
./narwhals/_compliant/dataframe.py
./narwhals/_compliant/expr.py
./narwhals/_compliant/group_by.py
./narwhals/_compliant/namespace.py
./narwhals/_compliant/selectors.py
./narwhals/_compliant/series.py
./narwhals/_compliant/typing.py
./narwhals/_compliant/when_then.py
./narwhals/_compliant/window.py
./narwhals/_constants.py
./narwhals/_dask
./narwhals/_dask/__init__.py
./narwhals/_dask/dataframe.py
./narwhals/_dask/expr.py
./narwhals/_dask/expr_dt.py
./narwhals/_dask/expr_str.py
./narwhals/_dask/group_by.py
./narwhals/_dask/namespace.py
./narwhals/_dask/selectors.py
./narwhals/_dask/utils.py
./narwhals/_duckdb
./narwhals/_duckdb/__init__.py
./narwhals/_duckdb/dataframe.py
./narwhals/_duckdb/expr.py
./narwhals/_duckdb/expr_dt.py
./narwhals/_duckdb/expr_list.py
./narwhals/_duckdb/expr_str.py
./narwhals/_duckdb/expr_struct.py
./narwhals/_duckdb/group_by.py
./narwhals/_duckdb/namespace.py
./narwhals/_duckdb/selectors.py
./narwhals/_duckdb/series.py
./narwhals/_duckdb/typing.py
./narwhals/_duckdb/utils.py
./narwhals/_duration.py
./narwhals/_enum.py
./narwhals/_expression_parsing.py
./narwhals/_ibis
./narwhals/_ibis/__init__.py
./narwhals/_ibis/dataframe.py
./narwhals/_ibis/expr.py
./narwhals/_ibis/expr_dt.py
./narwhals/_ibis/expr_list.py
./narwhals/_ibis/expr_str.py
./narwhals/_ibis/expr_struct.py
./narwhals/_ibis/group_by.py
./narwhals/_ibis/namespace.py
./narwhals/_ibis/selectors.py
./narwhals/_ibis/series.py
./narwhals/_ibis/utils.py
./narwhals/_interchange
./narwhals/_interchange/__init__.py
./narwhals/_interchange/dataframe.py
./narwhals/_interchange/series.py
./narwhals/_namespace.py
./narwhals/_pandas_like
./narwhals/_pandas_like/__init__.py
./narwhals/_pandas_like/dataframe.py
./narwhals/_pandas_like/expr.py
./narwhals/_pandas_like/group_by.py
./narwhals/_pandas_like/namespace.py
./narwhals/_pandas_like/selectors.py
./narwhals/_pandas_like/series.py
./narwhals/_pandas_like/series_cat.py
./narwhals/_pandas_like/series_dt.py
./narwhals/_pandas_like/series_list.py
./narwhals/_pandas_like/series_str.py
./narwhals/_pandas_like/series_struct.py
./narwhals/_pandas_like/typing.py
./narwhals/_pandas_like/utils.py
./narwhals/_polars
./narwhals/_polars/__init__.py
./narwhals/_polars/dataframe.py
./narwhals/_polars/expr.py
./narwhals/_polars/group_by.py
./narwhals/_polars/namespace.py
./narwhals/_polars/series.py
./narwhals/_polars/typing.py
./narwhals/_polars/utils.py
./narwhals/_spark_like
./narwhals/_spark_like/__init__.py
./narwhals/_spark_like/dataframe.py
./narwhals/_spark_like/expr.py
./narwhals/_spark_like/expr_dt.py
./narwhals/_spark_like/expr_list.py
./narwhals/_spark_like/expr_str.py
./narwhals/_spark_like/expr_struct.py
./narwhals/_spark_like/group_by.py
./narwhals/_spark_like/namespace.py
./narwhals/_spark_like/selectors.py
./narwhals/_spark_like/utils.py
./narwhals/_sql
./narwhals/_sql/__init__.py
./narwhals/_sql/dataframe.py
./narwhals/_sql/expr.py
./narwhals/_sql/group_by.py
./narwhals/_sql/typing.py
./narwhals/_sql/when_then.py
./narwhals/_translate.py
./narwhals/_typing_compat.py
./narwhals/_utils.py
./narwhals/dataframe.py
./narwhals/dependencies.py
./narwhals/dtypes.py
./narwhals/exceptions.py
./narwhals/expr.py
./narwhals/expr_cat.py
./narwhals/expr_dt.py
./narwhals/expr_list.py
./narwhals/expr_name.py
./narwhals/expr_str.py
./narwhals/expr_struct.py
./narwhals/functions.py
./narwhals/group_by.py
./narwhals/py.typed
./narwhals/schema.py
./narwhals/selectors.py
./narwhals/series.py
./narwhals/series_cat.py
./narwhals/series_dt.py
./narwhals/series_list.py
./narwhals/series_str.py
./narwhals/series_struct.py
./narwhals/stable
./narwhals/stable/__init__.py
./narwhals/stable/v1
./narwhals/this.py
./narwhals/translate.py
./narwhals/typing.py
./narwhals/utils.py
./noxfile.py
./pyproject.toml
./tests
./tpch
./tpch/README.md
./tpch/__init__.py
./tpch/execute.py
./tpch/generate_data.py
./tpch/queries
./tpch/queries/__init__.py
./tpch/queries/q1.py
./tpch/queries/q10.py
./tpch/queries/q11.py
./tpch/queries/q12.py
./tpch/queries/q13.py
./tpch/queries/q14.py
./tpch/queries/q15.py
./tpch/queries/q16.py
./tpch/queries/q17.py
./tpch/queries/q18.py
./tpch/queries/q19.py
./tpch/queries/q2.py
./tpch/queries/q20.py
./tpch/queries/q21.py
./tpch/queries/q22.py
./tpch/queries/q3.py
./tpch/queries/q4.py
./tpch/queries/q5.py
./tpch/queries/q6.py
./tpch/queries/q7.py
./tpch/tests
./utils
./utils/__init__.py
./utils/api-completeness.md.jinja
./utils/bump_version.py
./utils/check_api_reference.py
./utils/check_dist_content.py
./utils/check_docstrings.py
./utils/check_for_no_build_errors.py
./utils/generate_backend_completeness.py
./utils/generate_random_versions.py
./utils/generate_zen_content.py
./utils/import_check.py
```