change: Implement 5: Save selected images to the caller directory and downscale only behind the resize flag

Implemented image saving into the caller directory and exact-size downscaling behind --resize.

tools/images.py: added stdlib-only helpers `png_chunks`, `decode_png`, `encode_png`, `ico_wrap`, `ico_unwrap`, plus `decode_image`, `resample_rows`, `encode_image` and the `DecodedImage` dataclass; also fixed a real pixel-stride bug in RGBA upsampling (channel step was used as pixel stride, corrupting 8-bit pixels).

tools/example.py: removed the inlined codec (now delegated to tools.images); `--download` writes each selected image into the caller-specified directory; each stored file is read back and decoded, so a reported path only names a file that exists and opens as the requested format (`format`/`width`/`height`/`bytes` reported per item, no path for a failed item); `--download` without `--output-dir` is now an `invalid_request` (`request_field`, field=output_dir) instead of a hidden default, and DEFAULT_OUTPUT_DIR is gone; `--resize` stores exactly the requested width/height (one open dimension keeps the source value), re-encodes in the requested format, never upscales and leaves a fitting image's bytes untouched; a per-item save failure is reported in that item and ends the run with `partial_download` (exit 6), including `saved_paths` in the error details.

tests/test_download_resize.py: new focused suite over tmp_path dirs and locally built png/ico fixtures (save paths exist and decode, requested-format check, missing --output-dir invalid_request, failing save => partial_download, exact resize dims for png and ico, no upscaling, byte/dimension preservation without --resize, plus codec round-trip tests).
tests/test_cli.py: updated the aspect-ratio resize expectation to the required exact 100x100 stored size.

Target branch task/1-task is already the current head (d5bb24f), so the tested revision contains the target.

Tests:
Facade commands run from /workspace with .venv/bin on PATH (prepared via prepare_environment tools restore): `python -m compileall tools tests` (tools.validate) OK; `python -m tools.example examples/input.json` (tools.smoke) exit 0 with status dry_run; `python -m tools.example --help` (acceptance help-command) exit 0; `python -c "import tools, tools.example, tools.images"` (package_import) OK; `pytest` (tools.test, the exact facade entrypoint) => 142 passed. New tests: tests/test_download_resize.py (13 tests). No network-dependent live-source check was run (sandbox has no egress); all fixtures are locally built real png/ico payloads.

Progress:
Completed issue 7: stdlib PNG/ICO decode/encode/wrap/unwrap plus resample helpers live in tools/images.py; tools/example.py saves selected images into the caller directory, requires --output-dir with --download (invalid_request otherwise), verifies every stored file by decoding it before reporting its path, downscales to exactly the requested width/height in the requested format only when --resize is set (never upscaling, otherwise byte-identical), and reports a per-item save failure with the partial_download status/exit code. New tests in tests/test_download_resize.py cover all of that; tests/test_cli.py resize expectation aligned with the exact-size requirement. Facade validate/smoke/help/import all pass and `pytest` reports 142 passed on the revision that already contains target task/1-task.

Published by developer-agent through Tool Backend.

Closes #7

.agent-work/ledger.json

@@ -21,6 +21,11 @@
         "Implemented byte-based format and minimum-size filtering for the image search path. New tools/images.py: detect_format (png/ico plus jpeg/gif/bmp/webp so \"other format\" is distinguishable from \"unreadable\"), read_png_dimensions (IHDR), read_ico_dimensions (ICONDIR entries, 0 => 256, largest entry), inspect_image/ImageInfo, ImageFormatError (code image_unreadable), and png_bytes/ico_bytes builders. tools/example.py: candidate_cap(count) bounded window (count*4, max 50) requested from the source, _select() fetches and parses every candidate, KeptImage.to_item() reports source/url/format/actual width+height/size_bytes, _download() writes the already verified bytes, and _execute() distinguishes ok/no_format/no_size/access_error/partial_download with the existing exit codes; metadata-based filtering removed. tests/test_images.py added (31 tests) and tests/test_cli.py fixtures aligned to real image bytes. All facade commands pass: compileall, pytest (114 passed), smoke, help, package import.",
         "Addressed changes-requested review on PR #14: the CLI no longer turns common live-source results into partial_download/access_error. Any payload whose real format is not the requested png/ico (jpeg, gif, bmp, webp, svg, tiff, pdf, or an unrecognised body such as an HTML page) is now a format mismatch feeding no_format, with observed_formats/other_format_candidates detail; only unfetchable candidates are failures, and access_error is emitted only when nothing at all could be fetched. images.detect_format gained svg/tiff/pdf recognition and ImageFormatError is scoped to genuinely unusable png/ico payloads. Statuses/exits unchanged (no_format 3, no_size 4, access_error 5). Tests extended in tests/test_images.py (svg/tiff/pdf detection, mixed-format window stays ok, ico-only-foreign yields no_format, no_size preserved alongside other formats, non-image body is no_format, unfetchable candidate does not demote a search, corrupt png does not hide a match, empty window) and tests/test_cli.py aligned. Facade validate/test/smoke/help all green (129 passed) on the integrated branch; no protected facade paths touched."
       ]
+    },
+    "projects/product-54354138-1#7": {
+      "events": [
+        "Completed issue 7: stdlib PNG/ICO decode/encode/wrap/unwrap plus resample helpers live in tools/images.py; tools/example.py saves selected images into the caller directory, requires --output-dir with --download (invalid_request otherwise), verifies every stored file by decoding it before reporting its path, downscales to exactly the requested width/height in the requested format only when --resize is set (never upscaling, otherwise byte-identical), and reports a per-item save failure with the partial_download status/exit code. New tests in tests/test_download_resize.py cover all of that; tests/test_cli.py resize expectation aligned with the exact-size requirement. Facade validate/smoke/help/import all pass and `pytest` reports 142 passed on the revision that already contains target task/1-task."
+      ]
     }
   }
 }