Improve prediction popup latency: domain settings cache + remove tabs.get pre-flight#291
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bartekplus merged 1 commit intomasterfrom Mar 9, 2026
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…ing tabs.get pre-flight
Two performance bottlenecks were causing ~15-25 ms of avoidable overhead on
every keystroke prediction:
1. `resolveDomainRuntimeSettings` was called on every prediction request,
performing 5 parallel chrome.storage reads (~5-15 ms) even though domain
settings virtually never change between keystrokes.
Fix: introduce `DomainSettingsCache` (500 ms TTL, per-domain key) in
`MessageRouter`. The cache is immediately invalidated when
`CMD_OPTIONS_PAGE_CONFIG_CHANGE` is received so settings changes still
take effect without waiting for expiry.
2. `BackgroundServiceWorker.runPrediction` called `chrome.tabs.get` before
every `sendMessage` as a tab-existence pre-flight, adding ~5-10 ms of
extra IPC latency. `sendMessage` already throws when the tab/frame is
gone, so the pre-flight was redundant.
Fix: call `chrome.tabs.sendMessage` directly and catch the error.
Performance gain per keystroke: ~15-25 ms less background-side overhead.
50 consecutive predictions for the same domain now incur 1 storage read
instead of 250.
Tests added:
- `tests/DomainSettingsCache.test.ts` — 11 unit tests covering cache hit/miss,
TTL expiry, per-domain isolation, invalidation, and a latency benchmark
asserting cached requests are ≥5× faster than uncached ones.
- Two regression tests in `tests/background.routing.test.ts`:
- Verifies `chrome.tabs.get` is NOT called during prediction dispatch.
- Verifies the domain settings cache is invalidated after a config change
so the next prediction sees fresh language/settings values.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
DomainSettingsCache— cachesresolveDomainRuntimeSettingsper domain URL with a 500 ms TTL inMessageRouter. Previously, every keystroke prediction triggered 5 parallelchrome.storagereads (≈5–15 ms overhead). Now 50 consecutive predictions for the same domain cost 1 storage read instead of 250. Cache is immediately invalidated onCMD_OPTIONS_PAGE_CONFIG_CHANGE.chrome.tabs.getpre-flight —BackgroundServiceWorker.runPredictionwas callingchrome.tabs.get(tabId, callback)before everysendMessagejust to check if the tab existed, adding ≈5–10 ms of IPC latency.sendMessagealready throws if the tab is gone, so the check was redundant. Now sends directly.Total saving per keystroke: ~15–25 ms of background overhead.
Tests run
bun run lint✅bun run format:check✅bun run test✅ — 1304 pass, 0 failbun run test:e2e(pending CI)bun run check:e2e:coverage(pending CI)New tests added:
tests/DomainSettingsCache.test.ts— 11 unit tests: cache hit/miss, TTL expiry, per-domain isolation, invalidation, and a latency benchmark (cached path ≥5× faster than uncached with 2 ms simulated storage delay).tests/background.routing.test.ts:chrome.tabs.getis not called during prediction response dispatch.CMD_OPTIONS_PAGE_CONFIG_CHANGEso the next prediction sees the updated language.🤖 Generated with Claude Code