fix: register cache writes with waitUntil so they persist on workerd

[bookingseo]

Problem

Five cache-write sites use void setCached(...) — a fire-and-forget promise that is never awaited and never registered with waitUntil:

• DomainService.ts — domain overview (domain.rankOverview, ~100–300 credits/call) and keyword suggestions
• domainKeywordsPage.ts / domainPagesPage.ts — paginated domain keyword/page views
• keywords/services/research/serp.ts — SERP research analysis

On Cloudflare Workers, workerd cancels unregistered pending I/O once the response is sent, so the R2 put behind these calls is dropped before it lands. The 12-hour caches these services advertise never actually persist — every identical call re-issues the full metered DataForSEO request.

Easy to miss because everything looks fine functionally: results come back, the .catch never fires (the promise is cancelled, not rejected), and dev-mode/miniflare often lets the write finish anyway.

Fix

Register the writes with waitUntil from cloudflare:workers, matching the pattern already used elsewhere in the codebase (instrumentation.ts, brandLookup.ts, promptExplorer.ts). Response latency is unchanged — the write still happens after the response, it just isn't cancelled anymore.

No behavior change beyond the writes becoming durable. 613 tests green, tsc clean.

(Found while auditing our deployment's DataForSEO spend — cache hit-rate for get_domain_overview was 0% despite repeated identical calls.)

Greptile Summary

This PR changes R2 cache writes so they persist after the Worker response returns. The main changes are:

• Registers domain overview and keyword suggestion cache writes with waitUntil.
• Registers paginated domain keyword and page cache writes with waitUntil.
• Registers SERP analysis cache writes with waitUntil.
• Keeps existing cache keys, TTLs, DataForSEO calls, and response shaping unchanged.

Confidence Score: 5/5

Safe to merge with minimal risk.

The change is narrowly scoped to an established waitUntil(setCached(...).catch(...)) pattern. Cache keys, TTLs, request inputs, response schemas, and data shaping stay unchanged. No correctness or security issues were found in the changed paths.

No files require special attention.

T-Rex Logs

What T-Rex did

• Validated that the TypeScript compile for server-cache-waituntil completed cleanly with EXIT_CODE: 0.
• Verified the Vitest run for server-cache-waituntil passed, with 3 test files and 19 tests.
• Confirmed the static waitUntil cache registration check passed (RESULT: PASS; EXIT_CODE: 0) for the updated changes.
• Recognized that a verification harness script was generated and used for the static check.

_{Ran code and verified through T-Rex}

Important Files Changed

Filename	Overview
src/server/features/domain/services/DomainService.ts	Replaces fire-and-forget domain overview and keyword suggestion cache writes with waitUntil registration.
src/server/features/domain/services/domainKeywordsPage.ts	Registers paginated domain keyword cache writes with waitUntil while preserving the existing cached/fetch/return flow.
src/server/features/domain/services/domainPagesPage.ts	Registers paginated domain page cache writes with waitUntil without changing request parameters or response shaping.
src/server/features/keywords/services/research/serp.ts	Registers SERP analysis cache writes with waitUntil so successful DataForSEO responses can persist after response completion.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
participant Caller
participant Service as Domain/SERP service
participant R2 as R2 cache
participant DFS as DataForSEO
participant Worker as workerd waitUntil

Caller->>Service: request domain/SERP data
Service->>R2: getCached(cacheKey)
alt cache hit
    R2-->>Service: cached result
    Service-->>Caller: return cached result
else cache miss
    Service->>DFS: fetch metered data
    DFS-->>Service: API result
    Service->>Worker: waitUntil(setCached(cacheKey, result, ttl))
    Service-->>Caller: return fresh result
    Worker->>R2: persist cache write after response
end

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%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
participant Caller
participant Service as Domain/SERP service
participant R2 as R2 cache
participant DFS as DataForSEO
participant Worker as workerd waitUntil

Caller->>Service: request domain/SERP data
Service->>R2: getCached(cacheKey)
alt cache hit
    R2-->>Service: cached result
    Service-->>Caller: return cached result
else cache miss
    Service->>DFS: fetch metered data
    DFS-->>Service: API result
    Service->>Worker: waitUntil(setCached(cacheKey, result, ttl))
    Service-->>Caller: return fresh result
    Worker->>R2: persist cache write after response
end

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_{Reviews (1): Last reviewed commit: "fix: register cache writes with waitUnti..." | Re-trigger Greptile}

[bensenescu]

@greptileai

[bensenescu]

thanks, great find! Appreciate it