fix: correct UTC/localtime mismatch in skip_repeated_notifications cooldown

[Copilot]

devSkipRepeated was silently ineffective in any timezone ahead of UTC. SQLite's 'localtime' modifier on the RHS inflated "now" by the UTC offset (e.g. +7200s for UTC+2), making the cooldown window appear expired even for genuinely-recent notifications. A 2-hour cooldown in Europe/Warsaw DST provided zero suppression whatsoever.

Root cause — one-word SQL modifier in server/messaging/reporting.py:

-- Before (buggy): RHS is inflated by UTC offset
strftime('%s','now','localtime')/60

-- After (fixed): both sides are plain UTC epoch seconds
strftime('%s','now')/60

devLastNotification is stored as UTC; the comparison must use UTC on both sides.

Changes:

• server/messaging/reporting.py — remove 'localtime' from the strftime call
• test/backend/test_skip_repeated_notifications.py — four new unit tests:
  • recent notification → suppressed
  • expired cooldown → not suppressed
  • regression: UTC timestamp 20 min ago with 2 h cooldown → suppressed (would fail with the original bug)
  • devSkipRepeated=0 → never suppresses

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🔍 Related Issues

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📋 Type of Change

• 🐛 Bug fix
• 🧪 Test addition or change

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📷 Screenshots or Logs (if applicable)

Before fix (UTC+2, devSkipRepeated=2, last notification 20 min ago):

lhs_min(last_notif+skip)=29776211  rhs_min(now_local)=29776331  would_suppress=0  ← broken
lhs_min(last_notif+skip)=29776211  rhs_min(now_utc)=29776211    would_suppress=1  ← fixed

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🧪 Testing Steps

PYTHONPATH=server python -m unittest test.backend.test_skip_repeated_notifications -v — all 4 tests pass.

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✅ Checklist

• I have read the Contribution Guidelines
• I have tested my changes locally
• I have updated relevant documentation (if applicable)
• I have verified my changes do not break existing behavior
• I am willing to respond to requested changes and feedback

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🙋 Additional Notes

Note: app.conf's TIMEZONE setting does not affect SQLite's 'localtime' modifier — that reads the OS/process TZ. The bug only manifests when the container's actual TZ is non-UTC.

• Fixes Skip Repeated Notifications (devSkipRepeated) is silently inert in most timezones due to a UTC/localtime mismatch in the cooldown comparison #1737

[jokob-sk]

do not create db mocks directly, use existing main/test/db_test_helpers.py if needed

[Copilot]

Updated in commit e5e1e7b — the test now imports make_db, minutes_ago, and DummyDB from db_test_helpers instead of creating its own DB mock.

[jokob-sk]

mac should be always lower case

[Copilot]

Fixed in commit e5e1e7b — all MACs are now lowercase (e.g. aa:bb:cc:dd:ee:01).

[jokob-sk]

@copilot target the next_release branch, not main

[Copilot]

@copilot target the next_release branch, not main

The code changes are already on the copilot/fix-skip-repeated-notifications branch — only the PR's base branch needs to be updated from main to next_release. I don't have the permissions or a token available in this environment to change the PR base via the API. Could you update it directly via the GitHub UI (Edit → Base → next_release) or run gh pr edit 1738 --base next_release?