change: Implement 3: Complete the native-process CLI, JSON request handling, status vocabulary and exit codes

Completed the native-process CLI for `python -m tools.example`. Added `tools/envelope.py` with the fixed status vocabulary (`ok`, `dry_run`, `invalid_request`, `no_format`, `no_size`, `access_error`, `partial_download`) mapped to exit codes 0/0/2/3/4/5/6 and the `Response`/`ResponseBuilder` JSON envelope (keys: status, source, request, items, error). Extended `tools/errors.py` with request errors (`RequestError`, `RequestDocumentError`, `RequestFieldError`, `UnsupportedFormatError`) and `ACCEPTED_FORMATS`. Rewrote `tools/example.py` as a plain executable CLI accepting either a JSON request document or flags (--topic, --width, --height, --format png|ico, --source, --count, --download, --output-dir, --resize, --dry-run), with a custom parser that turns usage errors into `invalid_request` envelopes, unknown sources reported together with the available source ids, unsupported formats rejected with the accepted values, and format/size filtering, download and partial-download handling mapped onto the shared status table. `examples/input.json` is now the canonical offline dry_run request, and `tests/test_cli.py` (new) plus a rewritten `tests/test_example.py` cover the status/exit-code table, single-JSON-document output, help text, unknown source/unsupported format rejection and the download branches.

Tests:
Facade checks run from /workspace with the prepared .venv: `python -m compileall tools tests` (tools.validate) OK; `pytest` (tools.test) 76 passed; `python -m tools.example examples/input.json` (tools.smoke) exit 0 with a single `dry_run` JSON document; `python -m tools.example --help` exits 0 and documents every parameter plus the JSON document contract. Origin target branch `origin/task/1-task` (1f929c5) is an ancestor of the work branch, so the target is integrated and the checks above ran on the integrated revision. No dependency changes were needed, so no prepare_environment update was required.

Progress:
Implemented envelope status/exit-code table and response builder, request errors, the full flag/JSON-document CLI in tools/example.py, canonical offline examples/input.json, and CLI tests; facade validate/test/smoke and --help all pass (76 tests).

Published by developer-agent through Tool Backend.

Closes #5

tests/test_cli.py

@@ -0,0 +1,342 @@
+"""Contract tests for the native-process CLI in :mod:`tools.example`."""
+
+from __future__ import annotations
+
+import json
+import subprocess
+import sys
+from pathlib import Path
+from typing import Any, Sequence
+
+import pytest
+
+from tools import envelope, example
+from tools.errors import SourceAccessError
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+EXAMPLE_REQUEST = REPO_ROOT / "examples" / "input.json"
+
+
+def run_cli(*args: str) -> subprocess.CompletedProcess[str]:
+    return subprocess.run(
+        [sys.executable, "-m", "tools.example", *args],
+        cwd=REPO_ROOT,
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+
+
+def single_document(result: subprocess.CompletedProcess[str]) -> dict[str, Any]:
+    """Assert stdout holds exactly one machine-readable JSON document."""
+
+    lines = [line for line in result.stdout.splitlines() if line.strip()]
+    assert len(lines) == 1, result.stdout
+    assert result.stderr == ""
+    document = json.loads(lines[0])
+    assert isinstance(document, dict)
+    assert set(document) == {"status", "source", "request", "items", "error"}
+    return document
+
+
+def test_status_vocabulary_and_exit_codes_are_fixed() -> None:
+    assert envelope.STATUS_EXIT_CODES == {
+        "ok": 0,
+        "dry_run": 0,
+        "invalid_request": 2,
+        "no_format": 3,
+        "no_size": 4,
+        "access_error": 5,
+        "partial_download": 6,
+    }
+    assert envelope.STATUS_VOCABULARY == (
+        "ok",
+        "dry_run",
+        "invalid_request",
+        "no_format",
+        "no_size",
+        "access_error",
+        "partial_download",
+    )
+
+
+def test_help_documents_every_parameter() -> None:
+    result = run_cli("--help")
+
+    assert result.returncode == 0
+    for fragment in (
+        "REQUEST.json",
+        "--topic",
+        "--width",
+        "--height",
+        "--format",
+        "--source",
+        "--count",
+        "--download",
+        "--output-dir",
+        "--resize",
+        "--dry-run",
+        "png|ico",
+        "JSON",
+    ):
+        assert fragment in result.stdout, fragment
+
+
+def test_example_request_document_is_canonical_dry_run() -> None:
+    document = json.loads(EXAMPLE_REQUEST.read_text(encoding="utf-8"))
+    assert document["dry_run"] is True
+    assert document["format"] in ("png", "ico")
+
+    result = run_cli("examples/input.json")
+
+    assert result.returncode == envelope.EXIT_OK
+    payload = single_document(result)
+    assert payload["status"] == envelope.STATUS_DRY_RUN
+    assert payload["source"] == document["source"]
+    assert payload["items"] == []
+    assert payload["error"] is None
+    assert payload["request"]["topic"] == document["topic"]
+    assert payload["request"]["format"] == document["format"]
+
+
+def test_flags_dry_run_emits_one_document() -> None:
+    result = run_cli("--topic", "fox", "--format", "png", "--width", "640", "--dry-run")
+
+    assert result.returncode == envelope.EXIT_OK
+    payload = single_document(result)
+    assert payload["status"] == envelope.STATUS_DRY_RUN
+    assert payload["request"]["width"] == 640
+    assert payload["request"]["dry_run"] is True
+
+
+def test_unsupported_format_is_invalid_request() -> None:
+    result = run_cli("--topic", "fox", "--format", "gif")
+
+    assert result.returncode == envelope.EXIT_INVALID_REQUEST
+    payload = single_document(result)
+    assert payload["status"] == envelope.STATUS_INVALID_REQUEST
+    assert payload["error"]["code"] == "request_format_unsupported"
+    assert payload["error"]["details"]["accepted_formats"] == ["png", "ico"]
+
+
+def test_unknown_source_lists_available_ids() -> None:
+    result = run_cli("--topic", "fox", "--format", "png", "--source", "nope")
+
+    assert result.returncode == envelope.EXIT_INVALID_REQUEST
+    payload = single_document(result)
+    assert payload["status"] == envelope.STATUS_INVALID_REQUEST
+    assert payload["error"]["code"] == "source_unknown"
+    available = payload["error"]["details"]["available_sources"]
+    assert "nope" not in available
+    assert "wikimedia_commons" in available
+    assert len(available) >= 2
+
+
+def test_no_request_is_invalid_request() -> None:
+    result = run_cli()
+
+    assert result.returncode == envelope.EXIT_INVALID_REQUEST
+    payload = single_document(result)
+    assert payload["status"] == envelope.STATUS_INVALID_REQUEST
+
+
+def test_document_combined_with_flags_is_invalid_request() -> None:
+    result = run_cli("examples/input.json", "--topic", "fox")
+
+    assert result.returncode == envelope.EXIT_INVALID_REQUEST
+    payload = single_document(result)
+    assert payload["error"]["details"]["conflicting_flags"] == ["topic"]
+
+
+@pytest.mark.parametrize(
+    "arguments",
+    [
+        ("--format", "png"),
+        ("--topic", "fox"),
+        ("--topic", "fox", "--format", "png", "--count", "0"),
+        ("--topic", "   ", "--format", "png"),
+    ],
+)
+def test_incomplete_requests_are_invalid(arguments: Sequence[str]) -> None:
+    result = run_cli(*arguments)
+
+    assert result.returncode == envelope.EXIT_INVALID_REQUEST
+    assert single_document(result)["status"] == envelope.STATUS_INVALID_REQUEST
+
+
+def test_missing_document_file_is_invalid_request(tmp_path: Path) -> None:
+    result = run_cli(str(tmp_path / "absent.json"))
+
+    assert result.returncode == envelope.EXIT_INVALID_REQUEST
+    assert single_document(result)["status"] == envelope.STATUS_INVALID_REQUEST
+
+
+def test_malformed_document_is_invalid_request(tmp_path: Path) -> None:
+    broken = tmp_path / "broken.json"
+    broken.write_text("{not json", encoding="utf-8")
+
+    result = run_cli(str(broken))
+
+    assert result.returncode == envelope.EXIT_INVALID_REQUEST
+    assert single_document(result)["status"] == envelope.STATUS_INVALID_REQUEST
+
+
+class FakeCandidate:
+    """Minimal stand-in for :class:`tools.sources.SourceCandidate`."""
+
+    def __init__(
+        self,
+        title: str,
+        file_url: str,
+        mime_type: str,
+        width: int | None,
+        height: int | None,
+        *,
+        payload: bytes = b"payload",
+        fail: bool = False,
+    ) -> None:
+        self.source_id = "fake"
+        self.title = title
+        self.file_url = file_url
+        self.page_url = file_url + ".html"
+        self.mime_type = mime_type
+        self.width = width
+        self.height = height
+        self.license = "CC0"
+        self.creator = "tester"
+        self._payload = payload
+        self._fail = fail
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "source_id": self.source_id,
+            "title": self.title,
+            "file_url": self.file_url,
+            "page_url": self.page_url,
+            "mime_type": self.mime_type,
+            "width": self.width,
+            "height": self.height,
+        }
+
+    def fetch_bytes(self) -> bytes:
+        if self._fail:
+            raise SourceAccessError("download refused", url=self.file_url)
+        return self._payload
+
+
+class FakeRegistry:
+    def __init__(self, candidates: Sequence[FakeCandidate] = (), error: Exception | None = None) -> None:
+        self._candidates = list(candidates)
+        self._error = error
+        self.calls: list[tuple[str, str, int]] = []
+
+    def available_sources(self) -> Sequence[str]:
+        return ["fake"]
+
+    def search(self, source_id: str, topic: str, limit: int = 10) -> list[FakeCandidate]:
+        self.calls.append((source_id, topic, limit))
+        if self._error is not None:
+            raise self._error
+        return self._candidates[:limit]
+
+
+
+
+def run_main(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str], registry: FakeRegistry, *args: str) -> tuple[int, dict[str, Any]]:
+    monkeypatch.setattr(example, "default_registry", lambda: registry)
+    code = example.main(list(args))
+    captured = capsys.readouterr()
+    assert captured.err == ""
+    lines = [line for line in captured.out.splitlines() if line.strip()]
+    assert len(lines) == 1, captured.out
+    return code, json.loads(lines[0])
+
+
+BASE_ARGS = ("--topic", "fox", "--format", "png", "--width", "100", "--height", "100", "--source", "fake")
+
+
+def test_ok_lists_items_without_download(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]) -> None:
+    registry = FakeRegistry([FakeCandidate("fox one", "https://example.test/a.png", "image/png", 100, 100)])
+
+    code, payload = run_main(monkeypatch, capsys, registry, *BASE_ARGS)
+
+    assert code == envelope.EXIT_OK
+    assert payload["status"] == envelope.STATUS_OK
+    assert payload["source"] == "fake"
+    assert [item["file_url"] for item in payload["items"]] == ["https://example.test/a.png"]
+    assert payload["items"][0]["width"] == 100
+    assert registry.calls == [("fake", "fox", 10)]
+
+
+def test_no_format_when_source_has_no_matching_mime(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]) -> None:
+    registry = FakeRegistry([FakeCandidate("fox", "https://example.test/a.jpg", "image/jpeg", 100, 100)])
+
+    code, payload = run_main(monkeypatch, capsys, registry, *BASE_ARGS)
+
+    assert code == envelope.EXIT_NO_FORMAT
+    assert payload["status"] == envelope.STATUS_NO_FORMAT
+
+
+def test_no_size_when_only_smaller_images_exist(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]) -> None:
+    registry = FakeRegistry([FakeCandidate("fox", "https://example.test/a.png", "image/png", 50, 50)])
+
+    code, payload = run_main(monkeypatch, capsys, registry, *BASE_ARGS)
+
+    assert code == envelope.EXIT_NO_SIZE
+    assert payload["status"] == envelope.STATUS_NO_SIZE
+
+
+def test_resize_accepts_larger_images(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]) -> None:
+    registry = FakeRegistry([FakeCandidate("fox", "https://example.test/a.png", "image/png", 400, 300)])
+
+    code, payload = run_main(monkeypatch, capsys, registry, *BASE_ARGS, "--resize")
+
+    assert code == envelope.EXIT_OK
+    assert payload["request"]["resize"] is True
+    assert len(payload["items"]) == 1
+
+
+def test_download_success_writes_files(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str], tmp_path: Path) -> None:
+    registry = FakeRegistry([FakeCandidate("fox", "https://example.test/a.png", "image/png", 100, 100)])
+
+    code, payload = run_main(monkeypatch, capsys, registry, *BASE_ARGS, "--download", "--output-dir", str(tmp_path))
+
+    assert code == envelope.EXIT_OK
+    download = payload["items"][0]["download"]
+    assert download["ok"] is True
+    target = Path(download["path"])
+    assert target.parent == tmp_path
+    assert target.read_bytes() == b"payload"
+
+
+def test_partial_download_reports_status(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str], tmp_path: Path) -> None:
+    registry = FakeRegistry(
+        [
+            FakeCandidate("fox", "https://example.test/a.png", "image/png", 100, 100),
+            FakeCandidate("fox2", "https://example.test/b.png", "image/png", 100, 100, fail=True),
+        ]
+    )
+
+    code, payload = run_main(monkeypatch, capsys, registry, *BASE_ARGS, "--count", "2", "--download", "--output-dir", str(tmp_path))
+
+    assert code == envelope.EXIT_PARTIAL_DOWNLOAD
+    assert payload["status"] == envelope.STATUS_PARTIAL_DOWNLOAD
+
+
+def test_all_downloads_failing_is_access_error(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str], tmp_path: Path) -> None:
+    registry = FakeRegistry([FakeCandidate("fox", "https://example.test/a.png", "image/png", 100, 100, fail=True)])
+
+    code, payload = run_main(monkeypatch, capsys, registry, *BASE_ARGS, "--download", "--output-dir", str(tmp_path))
+
+    assert code == envelope.EXIT_ACCESS_ERROR
+    assert payload["status"] == envelope.STATUS_ACCESS_ERROR
+
+
+def test_search_access_error_maps_to_access_error(monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]) -> None:
+    registry = FakeRegistry(error=SourceAccessError("host unreachable", url="https://example.test"))
+
+    code, payload = run_main(monkeypatch, capsys, registry, *BASE_ARGS)
+
+    assert code == envelope.EXIT_ACCESS_ERROR
+    assert payload["status"] == envelope.STATUS_ACCESS_ERROR
+    assert payload["error"]["code"] == "source_access"