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Level 4 / Project 10 - Run Manifest Generator

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— This project — — Flashcards — Browser

Estimated time: 65 minutes

Focus

  • artifact manifest and run metadata

Why this project exists

This project gives you level-appropriate practice in a realistic operations context. Goal: run the baseline, alter behavior, break one assumption, recover safely, and explain the fix.

Run (copy/paste)

Use <repo-root> as the folder containing this repository's README.md.

cd <repo-root>/projects/level-4/10-run-manifest-generator
python project.py --dir data --output data/manifest.json --run-id my-batch-001
pytest -q

Expected terminal output

{
  "run_id": "my-batch-001",
  "file_count": 2,
  "total_size_bytes": 123
}
6 passed

Expected artifacts

  • data/manifest.json — file inventory with checksums and metadata
  • Passing tests
  • Updated notes.md

Checkpoint: Baseline code runs and all tests pass. Commit your work before continuing.

Alter it (required) — Extension

  1. Add a --algorithm flag supporting sha256 in addition to md5.
  2. Add a --exclude glob pattern to skip certain files (e.g., *.json).
  3. Re-run script and tests — add a test for SHA-256 checksums.

Break it (required) — Core

  1. Point --dir at a non-existent directory and observe the error.
  2. Create a very large file (10 MB+) and verify the chunked checksum still works.
  3. Create a directory with symlinks and see if they are followed or skipped.

Fix it (required) — Core

  1. Add a --no-follow-symlinks option to skip symbolic links.
  2. Handle permission errors gracefully (log a warning, skip the file).
  3. Re-run until all tests pass.

Checkpoint: All modifications done, tests still pass. Good time to review your changes.

Explain it (teach-back)

  1. Why does compute_checksum read in 8192-byte chunks instead of the whole file at once?
  2. What is the difference between iterdir() and rglob("*") in scan_files?
  3. Why does the manifest include timestamps and how would you use them for change detection?
  4. What are the security considerations of using MD5 vs. SHA-256 for checksums?

Mastery check

You can move on when you can: - run baseline without docs, - explain one core function line-by-line, - break and recover in one session, - keep tests passing after your change.

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