4.2.0c

API layer

• Introduce Update.fetch_raw_api(...) that performs a single-shot v3 request
  and, on failure, falls back to v2. We suppress chatter on a v3 success; on
  fallback we emit one concise notice to aid support triage. The first working
  endpoint becomes the new default for subsequent calls. :contentReference[oaicite:0]{index=0} :contentReference[oaicite:1]{index=1}
• Replace ad-hoc JSON fetches with decode_json_metadata(...), which reads
  once and caches by URL to reduce network churn. :contentReference[oaicite:2]{index=2}

Integrity & security

• Paper artifact downloads now always print a positive, single-line checksum
  confirmation on success and explicitly state when integrity checks are
  skipped (either forced or unavailable from the API). :contentReference[oaicite:3]{index=3}
• Script self-upgrade gains a separate SHA-256 verification path that derives
  the sidecar URL from GITHUB_RAW (.../.server_update.py.sha), prints the
  remote hash suffix before download, and validates post-download prior to
  install. This is isolated from the Paper jar flow. :contentReference[oaicite:4]{index=4} :contentReference[oaicite:5]{index=5}

Networking & timeouts

• Classify network failures with precise exits: timeout, HTTP, URL, connection,
  and unreachable. v2 is attempted on v3 timeouts/HTTP/URL/connection errors
  before fatal; both failing yields a single consolidated fatal. :contentReference[oaicite:6]{index=6} :contentReference[oaicite:7]{index=7}
• Tight, explicit timeouts on GitHub release fetch and sidecar download to keep
  CLI snappy and predictable during outages. :contentReference[oaicite:8]{index=8} :contentReference[oaicite:9]{index=9}

UX / operator feedback

• Standardize the upgrade transcript: “Starting Download”, progress bar, “Integrity
  test passed …”, and final completion banners; batch mode prints compact lines. :contentReference[oaicite:10]{index=10}
• Add explicit “Integrity check skipped” lines when disabled or when the API
  lacks a checksum, so logs are unambiguous. :contentReference[oaicite:11]{index=11}

CLI & flags

• --server-version reports local version/build and the remote build + full
  SHA256 from the API, aligning with the integrity display style elsewhere. (Code paths flow through the same metadata decode/cache as other commands.) :contentReference[oaicite:12]{index=12}
• Force/skip semantics emit clear one-liners (e.g. forced upgrade, skipped
  integrity/version check) to make intentional behavior obvious in logs. :contentReference[oaicite:13]{index=13}

Refactors & readability

• Rename legacy “get vs _get” split into descriptive roles:
  • “wire” → fetch_raw_api (returns a live HTTP stream with v3→v2 fallback)
  • “decode” → decode_json_metadata (parses + caches JSON)
    This reduces ambiguity between “fetching bytes” and “parsing structures.” :contentReference[oaicite:14]{index=14} :contentReference[oaicite:15]{index=15}

Safety & recovery

• Guard installs behind verified checksums; integrity mismatch prints an
  Expected/Actual diff and terminates with an actionable fatal. :contentReference[oaicite:16]{index=16}
• Self-upgrade refuses to operate on frozen binaries and exits cleanly. :contentReference[oaicite:17]{index=17}

Docs & comments

• Strengthened docstrings and inline explanations around version/build selection,
  API fallbacks, and integrity rationale to help future maintainers. :contentReference[oaicite:18]{index=18}
• The networking stack is now predictable: v3 once, v2 once, then fail—no loops,
  no silent hangs, and clear reasons on exit.