Windows native player and floating PiP (alpha)

[simonhagger]

Change

The Windows embedded MPV renderer gains an app-owned floating Picture in Picture window with hover controls, guarded seeking and clipping that keeps Angular controls usable without resizing the video. Opening minimized PiP restores the existing hosts. Returning or closing restores the main window; automatic disposal leaves focus alone. Playback keeps its session and provider connection.

This is the personal-fork integration of an optional upstream proposal. Browser PiP already exists upstream; this contribution adds the specialized Windows native window and shared capability/timeline refinements. External-player availability and earlier fork CI maintenance are already in the base and are not additions in this diff.

Alpha. Only Windows has been used for manual feature testing. macOS/Linux native and PiP runtime behavior remains unverified.

Corrections and validation

Current integration 0d757a0280670a06e88ab1a9863055a41bd43a8a includes both corrections to the previous matrix: playback policies use dedicated public subpath imports so they stay outside the startup bundle, and backend coverage excludes standalone HTML while retaining executable TS/JS/MJS instrumentation. Neither performance nor coverage limits was lowered.

• Production web/backend types and both owning spec programs passed. All three affected lint projects, guidance and release-note checks passed.
• Shared playback policy tests: 12 passed. Full playback tests: 150 suites / 1,630 tests passed. Focused backend regressions with coverage: seven suites / 120 tests passed, one existing skip.
• Coverage collection completed with no ownership errors or standalone HTML entries. Floating overlay JavaScript remains instrumented; its VM tests do not generate Istanbul hits, so no script hit coverage is claimed.
• Integrated production Electron build, including the Windows native addon, passed. Renderer initial payload measured 1,608,350 bytes against the unchanged 1,609,142-byte limit.
• Real Windows Electron smoke on this integration decoded synthetic HEVC, reopened the same minimized PiP hosts, restored/showed/focused the main window on Return, and disposed automatically without activating it. The paused session and media-request count stayed unchanged. All nine observed test-owned processes exited normally.
• Earlier comprehensive coverage evidence on the corrected source accepted all 34 genuine Tier A reports and unchanged aggregate/critical ratchets. The broader local Windows backend exploration still had 83 failed assertions in 15 unchanged platform/path fixture specs; that exploration is not claimed green. An unmodified Windows base run was not performed.
• Fresh GitHub unit/typecheck CI on 0d757a028 accepted all 34 coverage reports and unchanged health gates: statements 83.10%, branches 74.35%, functions 81.34%, lines 83.48%.
• Codex accepted committed integration 0d757a028 in review round two with no actionable regressions. Its own noninteractive dependency bootstrap aborted, so it did not run tests; the execution checks above ran separately on this same head. Greptile CLI is unavailable and was not run.

Publication gate

• Final committed integration Codex review accepted.
• Complete GitHub matrix green on the corrected integration head: all 29 checks passed.

All 29 checks passed on 0d757a028: CI, cross-platform E2E, packaging, CodeQL and Docker. This includes every Windows/Linux/macOS Electron shard and the previously failing startup-size and coverage gates. The optional upstream proposal is PR #1827.

Corrected source 85b2d910277eb133f8d626d90994a2bfde5291ed merges conflict-free with actual upstream master 2738bc28a1335ff19f87d67c5b1bbec3881b8e85. Current upstream itself has a failing performance-inventory check, involving serial-details.test-stubs.ts. Fork CI tests baseline bf3cf87b6 plus separately reviewed maintenance and is not proof of green latest-upstream integration. No automatic upstream merge is requested.

Release note: .changes/windows-native-mpv-alpha.md.