test: cover ErrorFormatter classify, transport seam, and path/session edges

[cursor]

Summary

Adds regression tests for modules extracted in the Jul 16 scraper refactor (c7f46b8). These paths handle network error classification, download progress payloads, transport seam wiring, redirect hardening, and path-builder edge cases — all high-blast-radius download flows with no dedicated coverage on main.

Risky behavior now covered

• ErrorFormatter.classify — connection, timeout, rate-limited (429 with retry delay), access (403/404), generic HTTP, redirect loops, and unknown errors
• DownloadTask — frozen 7-field progress schema used by workers/GUI signals
• LiveBoardApi — safe_get wiring for thread/catalog fetch and streaming range requests (default download timeout)
• safe_get redirect handling — redirect-loop cap (TooManyRedirects) and missing Location header fallback
• PathBuilder / limit_folder_length — catalog naming, empty-board fallback, truncation with trailing-separator strip

Changed files

File	Reason
tests/test_error_format.py	New — ErrorFormatter classification categories
tests/test_signals.py	New — DownloadTask schema/immutability
tests/test_transport_api.py	New — LiveBoardApi → safe_get contract
tests/test_session.py	Redirect loop + missing Location header
tests/test_paths.py	limit_folder_length + catalog/empty-board naming

Why these tests materially reduce regression risk

The Jul 16 refactor moved error handling, retry policy, chunking, and transport behind new seams. Without tests, a rename or signature drift in ErrorFormatter or LiveBoardApi could silently break user-facing error messages or bypass redirect allowlisting. These tests lock the contracts the GUI and workers depend on.

Testing performed

• uv run pytest tests/ -q --ignore=tests/test_gui.py — 97 passed
• uv run ruff check .
• Manual run on macOS / Apple Silicon

Safety notes

Test-only change; no production behavior modified.

Screenshots

N/A — no UI changes.

  

[RazorBackRoar]

Closing as superseded cleanup.

main already contains the needed CI/docs/test fixes. This was an automated draft autofix PR and is no longer needed.