Cache Similar Jobs tab with stale-while-revalidate

[camd]

Problem

The Similar Jobs tab in the job-details panel is unmounted by react-tabs when inactive and remounted on return, which resets its state (list, "Show previous jobs" pagination, selected job, and the "Exclude successful jobs" filter) and refetches everything — page 1 of similar jobs, the push data, and the auto-selected job's detail (JobModel.get + text-log-errors). Switching back felt like a full reload and lost the user's place.

Unlike bug suggestions, Similar Jobs is a live query over the Job table: new jobs of the same type land on nearly every push, and statuses of already-listed jobs change (a running job finishes, another user classifies/retriggers). That list is its own fetch, not fed by the main job-view poll, so it never self-updates today.

Change

Add a per-session snapshot cache (similarJobsCache) keyed by the investigated jobId, and restore it on mount, then stale-while-revalidate:

• Instant restore of the full tab state (list, loaded pages, selected job + its detail, filter) with no spinner.
• Background revalidate when the snapshot's list is older than a 30s dedup window: refetch all loaded pages in one request and refresh the selected job's detail, then swap the fresh data in — picking up newly-arrived same-type jobs and status changes on listed rows.
• Dedup window (30s) avoids refetching on rapid tab toggling.
• Mount guard lets a revalidate that resolves after the user tabs away update the cache while skipping setState.
• Bounded to 50 jobIds, evicting the oldest.

The tab's fetch logic is refactored into reusable fetchAndEnrich (page range) and fetchJobDetail helpers.

Out of scope / unaffected

The left job-info panel is untouched: the selected job's own status and log-parse status still update live via useJobDetails + the push poll (its effect re-runs on selectedJob.state/.result/.failure_classification_id). Only the other jobs listed in the Similar Jobs tab live in the snapshot, which is exactly what the revalidate refreshes. Continuous polling while the tab is visible is intentionally out of scope (revalidate-on-open only).

Tests

• similarJobsCache_test.js — store/retrieve, eviction, recency refresh, freshness window.
• SimilarJobsTab_test.jsx — cache-miss fetch+render, fresh-hit hydrate with no revalidate (dedup), stale-hit hydrate + background revalidate swap.

Note

Not yet driven in a real browser (needs a dev server + a job with similar-job history); the interaction flows are best confirmed with a live smoke test.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 84.54545% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.77%. Comparing base (740daac) to head (6f27069).

Files with missing lines	Patch %	Lines
ui/job-view/details/tabs/SimilarJobsTab.jsx	82.47%	15 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9669      +/-   ##
==========================================
+ Coverage   82.59%   82.77%   +0.17%     
==========================================
  Files         622      623       +1     
  Lines       36580    36647      +67     
  Branches     3279     3353      +74     
==========================================
+ Hits        30213    30334     +121     
+ Misses       6217     5929     -288     
- Partials      150      384     +234     

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