Player: Stream Quality panel (redesign of the Statistics popup)

[AKnassa]

What this does

Replaces the in-player Statistics popup with a Stream Quality panel that answers "will this play smoothly" in plain language.

What changed

• A colour-coded quality meter (Poor / Fair / Good) with a one-line verdict, e.g. "Smooth playback. No pauses expected."
• Each signal explains itself: Sources ("where your video streams from"), Buffer ("safe to watch before it loads more", in minutes/seconds), Speed ("faster/slower than you're watching").
• Buffer is read from the real player buffer, so it reflects whether playback will actually stall, not just total download progress.
• Raw details (Completed %, Info hash) move into a collapsible More details with a smooth expand animation; tap the info hash to copy it.
• No new dependencies, no extra backend calls (reuses data already fetched). The scoring/formatting logic is pure and covered by 93 unit tests.

How to see it

Play a torrent stream, then open the panel from the network icon in the control bar. Try a fresh stream, a healthy stream, and a fully-cached title.

Notes for reviewers

New user-facing strings are added inline as t('KEY', { defaultValue: '...' }). Here are the new keys that need adding to stremio-translations — I'm happy to open the matching PR there:

PLAYER_STREAM_QUALITY
PLAYER_QUALITY_CHECKING  PLAYER_QUALITY_GOOD  PLAYER_QUALITY_FAIR  PLAYER_QUALITY_POOR  PLAYER_QUALITY_LIMITED
PLAYER_QUALITY_VERDICT_CHECKING  PLAYER_QUALITY_VERDICT_CACHED  PLAYER_QUALITY_VERDICT_GOOD
PLAYER_QUALITY_VERDICT_FAIR  PLAYER_QUALITY_VERDICT_POOR  PLAYER_QUALITY_VERDICT_LIMITED
PLAYER_SIGNAL_SOURCES  PLAYER_SIGNAL_SOURCES_MEANING
PLAYER_SIGNAL_BUFFER  PLAYER_SIGNAL_BUFFER_MEANING  PLAYER_SIGNAL_BUFFER_MEANING_CACHED
PLAYER_SIGNAL_BUFFER_VALUE_CACHED  PLAYER_SIGNAL_BUFFER_VALUE_UNKNOWN
PLAYER_SIGNAL_SPEED  PLAYER_SIGNAL_SPEED_MEANING_OK  PLAYER_SIGNAL_SPEED_MEANING_SLOW  PLAYER_SIGNAL_SPEED_VALUE_CACHED
PLAYER_MORE_DETAILS  PLAYER_COMPLETED  PLAYER_INFO_HASH  PLAYER_COPY_INFO_HASH  PLAYER_INFO_HASH_COPIED
MB_S  COPIED

One deliberate design choice worth calling out: the meter fills to 99% for a perfectly streaming title and only reaches 100% for a fully-downloaded (cached) one, to keep those two states visually distinct.

[Botsy]

I reviewed and tested the changes. Overall, a clean, well-tested PR. Good call reframing raw numbers into a plain-language verdict. Pure logic extracted into streamQuality.js with solid edge-case test coverage; units consistent; conventions followed. 👍

A few non-blocking notes:

1. Cast path reads "Poor" for healthy streams. On the Chromecast sender path buffered is null (vs ms on the HTML path), so bufferAhead returns 0 and cast torrents score near-zero on buffer regardless of health. Regression from the old panel. Handle null-buffer or note cast as out of scope.

2. keepingUp === null scored as "not keeping up." Until duration is known (and for live streams), keepingUp is null, and keepingUp ? 20 : 0 docks 20 points at the moment the panel opens — healthy streams can transiently read Fair/Poor. Noted as a follow-up; flagging since it hits the primary case.

3. Minor: onCopyInfoHash deps are [infoHash] only — missing t/toast (stale translation on mid-stream language switch; likely trips exhaustive-deps).

4. Translations: the inline defaultValue strings are fine as a stopgap, but we'd expect the new PLAYER_QUALITY_* / PLAYER_SIGNAL_* keys to land in a matching PR on the stremio-translations repo before merge.

Thank you for contributing!

[kKaskak]

• Remove tests/streamQuality.spec.js; new tests are prohibited by repo guidance.
• Replace the arbitrary quality score with objective playback signals, or document product-approved thresholds.
• Account for playback speed when calculating buffer runway and required download speed.
• Show Limited when real player buffer data is unavailable; avoid promises like “will not buffer.”
• Add all strings to stremio-translations, bump the dependency when pr merged, and remove inline English fallbacks.
• Make the new helper TypeScript and remove unrelated/refactored code.
  Remove or split the info-hash copy feature into a separate PR.
• Squash into concise commits without commit bodies and shorten the PR description.
• Verify web, desktop shell, Chromecast, cached/fresh torrents, multiple playback speeds, and non-English UI.

[kKaskak]

also for reference we have added a simple contribution guide
https://github.com/Stremio/stremio-web/blob/development/CONTRIBUTING.md