feat(greenfield): add system metrics overview

[mira-2026]

Summary

• add a strict session-only system.metrics query for bounded CPU, memory, root-disk, aggregate network, uptime, sample-time, and freshness gauges
• collect metrics without shell execution or host/interface identity, coalesce concurrent reads, and serve an explicitly stale last-known-good sample for at most 30 seconds
• render an accessible five-second overview above the cache browser with shared measurement formatting, reusable metric cards, and Storybook coverage
• register generated contract documentation while keeping legacy GET /api/metrics and full / parity planned until their remaining projections are implemented

Behavior and regression coverage

• anonymous and automation principals are rejected before sampler access; the procedure has no automation capability and exposes only fixed safe outage text
• Linux network sampling warms across its first sample, counter resets, and clock regressions; unsafe counters, rates, capacity, and output shapes fail closed
• concurrent reads share one in-flight collection; failed refreshes may return a validated stale snapshot only inside the inclusive 30-second window
• TanStack Query forwards cancellation, polls every five seconds, retains validated data during refresh failures, and labels stale and warming states explicitly
• focused contract, procedure, collector, service, runtime, formatter, query, component, route, parity, and Storybook tests cover the slice

Verification

• bun run test:bun — 1594 passed
• bun run test:browser — 287 passed
• bun run storybook:test — 50 files / 170 tests passed
• bun run test:coverage — 91.77% (52657/57377 lines; required 85%)
• bun run typecheck
• bun run lint
• bun run format:check
• bun run check:boundaries
• bun run docs:check
• bun run db:check
• bun audit --production — no vulnerabilities
• bun run storybook:build
• bun run build:release — exact clean commit 12bca596d0a876cd418d852906e8db166f85c909
• independent read-only security/contract/runtime/UI audit — no blockers

Risk checklist

• No secrets, tokens, .env files, database dumps, runtime state, hostname, CPU model, or interface identity committed
• The new API query enforces browser-session authentication and strict Valibot input/output validation
• Raw collector failures remain internal and map only through the typed fixed-text SERVICE_UNAVAILABLE boundary
• No migration, dependency, configuration, realtime-topic, or control-authority change
• UI behavior is described above and covered by component, route, accessibility, cancellation, and Storybook tests

Deployment / operations

• No deploy, restart, migration, or configuration change needed for review
• Rollback is the ordinary revert of this isolated stacked commit

Notes for reviewers

• Base is frozen PR feat(greenfield): add Storybook and refresh test tooling #405 at 6eb53d8c09b2611f9d03d127f6ac0759f8653ce0.
• effect@4.0.0-beta.106 is the intentional audited parent version; this PR does not change it.
• Review the browser-session-only boundary, network baseline recovery, last-known-good age calculation, and retained-data UI states.

[coderabbitai]

Warning

Review limit reached

@mira-2026, you've reached your PR review limit, so we couldn't start this review.

Next review available in: 36 seconds

You've used all free OSS reviews for now. Wait for the free limit to reset to keep reviewing this public repository.

How can I continue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

To avoid repeated limits, reduce automatic review volume by pausing incremental auto-reviews earlier, using label-based review opt-in, excluding WIP or generated PR titles, or requesting reviews manually when the PR is ready. If your team needs uninterrupted high-volume reviews, an organization admin can enable usage-based reviews.

How do review limits work?

CodeRabbit enforces per-developer PR review limits for each organization. Most developers receive the normal plan review availability.

For paid Pro and Pro+ PR reviews, CodeRabbit uses adaptive limits for sustained high-volume activity. When a developer's recent PR review activity reaches the 95th percentile or higher among CodeRabbit users, additional reviews become available more gradually as earlier reviews age out of the rolling window.

Please refer docs for additional details.

Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 2b7614a3-4e54-4537-bfa6-5e07e0bba436

📥 Commits

Reviewing files that changed from the base of the PR and between 6eb53d8 and 12bca59.

⛔ Files ignored due to path filters (3)

• greenfield/docs/generated/procedures.md is excluded by !**/generated/** and included by **/*
• greenfield/docs/generated/schemas/system.metrics.input.schema.json is excluded by !**/generated/** and included by **/*
• greenfield/docs/generated/schemas/system.metrics.output.schema.json is excluded by !**/generated/** and included by **/*

📒 Files selected for processing (33)

• greenfield/.bun-browser-test-timings.json
• greenfield/.bun-test-timings.json
• greenfield/docs/architecture/greenfield-rewrite/progress.md
• greenfield/scripts/documentation/jsonSchema.ts
• greenfield/src/browser/cache/cachePresentation.ts
• greenfield/src/browser/lib/formatMeasurements.test.ts
• greenfield/src/browser/lib/formatMeasurements.ts
• greenfield/src/browser/overview/OverviewRoute.test.tsx
• greenfield/src/browser/overview/OverviewRoute.tsx
• greenfield/src/browser/overview/SystemMetricsCards.test.tsx
• greenfield/src/browser/overview/SystemMetricsCards.tsx
• greenfield/src/browser/overview/SystemMetricsSection.tsx
• greenfield/src/browser/overview/stories/SystemMetricsCards.stories.tsx
• greenfield/src/browser/overview/systemMetricsPresentation.test.ts
• greenfield/src/browser/overview/systemMetricsPresentation.ts
• greenfield/src/browser/overview/systemMetricsQueries.test.ts
• greenfield/src/browser/overview/systemMetricsQueries.ts
• greenfield/src/browser/ui/MetricCard.test.tsx
• greenfield/src/browser/ui/MetricCard.tsx
• greenfield/src/browser/ui/stories/MetricCard.stories.tsx
• greenfield/src/contracts/system.test.ts
• greenfield/src/contracts/system.ts
• greenfield/src/server/domains/system/procedures.test.ts
• greenfield/src/server/domains/system/procedures.ts
• greenfield/src/server/domains/system/systemMetricsCollector.test.ts
• greenfield/src/server/domains/system/systemMetricsCollector.ts
• greenfield/src/server/domains/system/systemMetricsService.test.ts
• greenfield/src/server/domains/system/systemMetricsService.ts
• greenfield/src/server/platform/runtime/applicationRuntime.test.ts
• greenfield/src/server/platform/runtime/applicationRuntime.ts
• greenfield/src/server/test/support/requestContext.ts
• greenfield/src/server/trpc/procedureErrorPolicy.ts
• greenfield/src/test/parity/fixtures/greenfield-contracts.json

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[codecov]

Codecov Report

❌ Patch coverage is 93.00813% with 43 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ield/src/browser/overview/SystemMetricsSection.tsx	73.75%	21 Missing ⚠️
...rc/server/domains/system/systemMetricsCollector.ts	93.75%	11 Missing ⚠️
.../src/server/domains/system/systemMetricsService.ts	91.66%	5 Missing ⚠️
greenfield/src/contracts/system.ts	95.06%	4 Missing ⚠️
greenfield/src/browser/ui/MetricCard.tsx	95.55%	2 Missing ⚠️

📢 Thoughts on this report? Let us know!