A staged tag was only retried on the refresh tick or a job completion, so a service with steady remote sessions never swapped in. Session end, expiry and eviction now trigger a single-flight apply, the tick applies after the pull, and serve.services_staged_max_age swaps an overdue tag in even while busy.
Answered login prompts and uploaded cache now count as client auth; the client closes on exit and keeps the remote session alive during long downloads.
Renames 314 defs and 41 module/class-level constants. Keeps 11 names underscored where the stripped form collides in scope, plus 5.5.0 shims for the three symbols external service repos call.
Delete code paths that never executed in the serve/API/remote stack:
- BridgeCancelledError: raised but never caught; replace raises with RuntimeError and drop the class.
- InputBridge.error setter and _error field: written at the handler layer, never read (session.auth_error is the surfaced channel).
- cancel_event param and _check_cancel inner fn on _perform_download: the only caller always passed None (the live job.cancel_event is untouched).
- result_with_progress monkeypatch: its status pings were redundant with the file-polled progress_sink, which is now the sole path.
- session param on _resolve_manifest_data: unused in the body.
Reconcile SessionStore's hardcoded 600s auth-state TTL into a shared AUTH_INPUT_TIMEOUT constant referenced by both the InputBridge input timeout and the store, removing the magic number without changing the longer grace window.
Update input_bridge/session_store tests for the new channels and add an assertion that auth-state entries expire at the single rule.
Missing requested subtitle and audio languages now warn and continue when --best-available is set instead of hard-exiting. Without the flag, missing languages still produce an error and exit, matching the prior strict behavior. Audio missing-lang detection is now symmetric with subtitles.
- add find_missing_langs helper in core/utilities for reuse between s_lang and a_lang paths (skips all/best/orig sentinels)
- refactor dl.py s_lang/a_lang checks to share the helper
- add tests/lang_selection covering match primitives, helper output, and tricky langcodes corners (zh-Hans/zh-Hant/zh-CN/zh-TW/zh-HK, cmn/yue, fil/tl/tgl)
- clean up unused-var ruff F841 in tests/remote/unit/
Covers RemoteClient/RemoteService, REST routes, handlers, SessionStore, InputBridge, DownloadQueueManager, errors, compression, and serve CLI. E2e tier opts in via --live and can auto-spawn its own serve.