Persist Request Insights session history (#97795)
## Summary
- Keep active requests and the latest 100 completed requests live. Page
older summaries and load full details from the current dev-server
session's 50 MiB journal.
- Complete requests when the outer router and HTTP response settle, so
long-running requests and Proxy passes do not finish or disappear
prematurely.
- Append late spans and fetches to the original record without reopening
it or extending its response duration.
- Batch adjacent completed-record writes and append incremental late
updates. Report journal rotation, and prevent discarded records from
being recreated by late work.
- Send only new spans and fetches over HMR, up to 128 records per
update. Absolute offsets handle snapshot overlap without losing or
duplicating records. Initial snapshots and retained history still
contain the full records.
- Expose retained history through the panel, CLI and MCP. Acquire the
dev-directory lock before initializing the journal.
History resets with a new dev-server process. This does not depend on
the pending Server Action, use-cache, cache-revalidation or
after-callback OpenTelemetry producers.
## Verification
- 66 focused store and reducer tests passed at this layer, including
lifecycle, late updates, pagination, rotation and incremental delivery.
- The rebuilt full stack passed 122 focused tests. History loading,
filters, trace inspection and live React timing updates passed in four
selected development scenarios with each bundler.
- Doubling the serialization test from 100 to 200 records now doubles
live-update bytes, rather than nearly quadrupling them.
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Co-authored-by: vercel-fleet-prod[bot] <318278635+vercel-fleet-prod[bot]@users.noreply.github.com>
Co-authored-by: Will Binns-Smith <755844+wbinnssmith@users.noreply.github.com>
