Fix HLS cleanup, investigation playback, backup I/O, and ONVIF handling

[matteius]

HLS cleanup changes process-wide signal dispositions, native investigation play/pause leaves shared controls out of sync, and backup verification repeatedly evicts pages it needs to reread. This PR fixes those behaviors and hardens ONVIF subscription URL handling and empty-response diagnostics.

• Remove HLS alarms, temporary SIGALRM/SIGSEGV handlers, and the freed-memory probe. Preserve FFmpeg-owned codec metadata until input closure, fixing the leak exposed by concurrent stream lifecycle tests.
• Synchronize native investigation play/pause with shared playback state while allowing the shared clock to continue through media reloads and clip boundaries.
• Retain reclaimable file cache during full backup integrity verification; keep copy-batch cache release, final eviction, abort checks, and deadlines. Schedule the next interval from completion and defer failed retries without counting them as successful backups.
• Parse the ONVIF destination from SubscriptionReference, support XML prefixes and escaped query strings, escape wsa:To, reject empty HTTP 200 responses, disable curl signal use, and log the action, curl/HTTP codes, and elapsed time.
• Add a repeatable RTSP/ONVIF harness that checks actual pre-trigger footage, plus a backup I/O benchmark and investigation notes.

Validation: frontend production build; six targeted C suites (backup, ONVIF, packet buffer, HLS cleanup, MP4 timestamps, and system API); two investigation browser tests; and two existing sub-stream/fullscreen browser tests passed. Concurrent HLS shutdown/restart passed with AddressSanitizer and LeakSanitizer enabled. The synthetic ONVIF test produced a decodable 31.4-second MP4 containing red footage before the trigger and blue footage afterward, with approximately eight seconds of pre-buffer.

The repeatable 82 MB audit fixture read 178 MB with repeated eviction versus 82 MB without it; both integrity checks passed. Verification can use more reclaimable OS page cache until completion. This small local benchmark does not predict production backup duration.

Related: #600, #603, #580, #604, #568, #494, #579. The affected cameras are unavailable, so the Tapo report, camera-specific pre-buffer behavior, and connection instability remain unconfirmed. Persistent SQLite I/O errors still need the extended error code and remain separate from backup performance. The reported HLS deadlock did not reproduce. Existing main-stream reuse behavior was verified without changing stream selection.

Detailed results and reproduction commands: backlog reliability notes.

[Copilot]

🟡 Changes recommended

HLS teardown still accesses potentially freed context memory, and the HLS test fixture does not clean up the global shutdown coordinator.

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Pull request overview

Fixes HLS cleanup, investigation playback synchronization, backup verification behavior, and ONVIF subscription handling.

Changes:

• Updates HLS lifecycle cleanup and FFmpeg metadata ownership.
• Synchronizes investigation playback controls and validates pre-buffering.
• Improves backup scheduling/cache handling and ONVIF parsing diagnostics.

File summaries

File	Description
web/js/components/preact/investigation/InvestigationView.jsx	Synchronizes native playback controls.
tests/unit/test_hls_cleanup.c	Adds concurrent HLS lifecycle coverage.
tests/unit/test_detection_system_onvif.c	Adds ONVIF regression tests.
tests/unit/CMakeLists.txt	Registers HLS cleanup tests.
tests/integration/synthetic-onvif-prebuffer.py	Adds repeatable pre-buffer validation.
tests/integration/specs/investigation.ui.spec.ts	Tests investigation playback synchronization.
tests/database/db_backup_test.c	Tests backup retry behavior.
tests/database/benchmark_backup_verification.py	Benchmarks verification I/O.
src/video/onvif_detection.c	Hardens ONVIF parsing and diagnostics.
src/video/hls/hls_unified_thread.c	Updates HLS lifecycle cleanup.
src/video/hls_writer.c	Removes alarm-based cleanup handling.
src/video/ffmpeg_utils.c	Preserves FFmpeg-owned metadata.
src/database/db_core.c	Adjusts backup scheduling and success tracking.
src/database/db_backup.c	Improves verification cache handling.
src/core/main.c	Updates shutdown signal handling.
src/core/daemon.c	Updates daemon signal handling comments.
docs/internal/BACKLOG_RELIABILITY_2026-09-12.md	Documents validation and findings.

Review details

Suppressed comments (1)

tests/unit/test_hls_cleanup.c:85

• setUp reinitializes the process-global shutdown coordinator for every test, but tearDown never calls shutdown_coordinator_cleanup(). After the first test, the next init_shutdown_coordinator() overwrites live pthread mutex/condition-variable objects with memset, which is undefined behavior and leaks their resources. Destroy the coordinator in tearDown before the next test starts.

void tearDown(void) {
    cleanup_all_hls_writers();
    remove_test_files(test_dir);
}

• Files reviewed: 17/17 changed files
• Comments generated: 2
• Review effort level: Lite

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