[AAASM-3512] ♻️ (dashboard): Harden Overview page — Sonar fixes + tests

[Chisanan232]

Description

Refactor-only hardening of the dashboard Overview page to clear the four
SonarCloud Reliability/Maintainability issues flagged on
dashboard/src/pages/OverviewPage.tsx, plus broader test coverage. No behaviour
change to the page — rendered output is identical.

SonarCloud rules fixed:

Line	Rule	Fix
L131	typescript:S4624 (nested template literals)	Hoisted the inner ${TONE_CLASS[...]} template into a named toneClass const in LayerCard.
L169	typescript:S3776 (Cognitive Complexity 18 > 15)	Extracted the pure KPI/score/alert derivations into deriveOverviewKpis + compareBySeverity in a sibling OverviewPage.kpis.ts module, and pulled the recent-decisions row into a RecentDecisionRow component. The component now destructures one helper result.
L191	typescript:S3735 (void operator)	Replaced void agentsQuery.refetch() with the repo's existing ignorePromise(...) helper (already used by every other page) — satisfies no-floating-promises, swallows unexpected rejections, tolerates the test mock's undefined return.
L239	typescript:S6772 (ambiguous JSX spacing)	Added explicit {' '} between "Overview" and the zh subtitle <span> in the <h1>.

Note: the helper was placed in a sibling .ts module (matching the repo's
fleetTypes / fleetFilters pattern) rather than exported from the component
file, because react-refresh/only-export-components forbids non-component
exports there. This also makes the pure derivation directly unit-testable.

Type of Change

• ♻️ Refactoring

Breaking Changes

• No

Related Issues

• Related Jira ticket: AAASM-3512

Testing

• Unit tests added / updated

Tests added:

• OverviewPage.kpis.test.ts (new, 9 cases) — deriveOverviewKpis branches:
  empty-fleet total === 0 full-score posture, mode/flag counting, identity &
  capability score degradation, identity clamp-at-zero, blocked/scrubbed
  null-as-zero summation, FIRING-only filtering + most-severe top-alert,
  no-firing undefined case; plus compareBySeverity ordering and the
  equal-severity (0) branch.
• OverviewPage.test.tsx (extended, +14 cases) — default 24h window + all four
  window-toggle states (1h/24h/7d/30d) asserting single-active + subtitle echo;
  singular/plural/healthy hero posture messages; fleet-snapshot mode/flag tile
  derivations; recent-decisions severity→decision mapping (deny/narrow/scrub)
  with agentId-vs-fleet rendering; empty recent note; approvals clear-vs-awaiting
  copy; fleet-wide top-issue with active-policy count. (loading/error/empty
  states were already covered and remain green.)

Local validation (all green):

• pnpm type-check — clean
• pnpm lint (--max-warnings 0) — clean
• pnpm build — succeeds (pre-existing chunk-size warnings only)
• pnpm test — 148 files / 1326 tests passed (Overview suite: 22 + KPI suite: 9)

Checklist

• Self-review of the diff completed
• All local checks passing
• Commits are small and follow the Gitmoji convention

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 95.65217% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
dashboard/src/pages/OverviewPage.tsx	87.50%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

[Chisanan232]

🔎 Review (Claude Code) — ready for approval

CI: ✅ All green — 0 failures (Dashboard tests + coverage, aa-cli build compat, CI Success all pass). The codecov/patch-class acceptance check is non-blocking.

Scope vs AAASM-3512: ✅ Fixes all 4 listed SonarCloud issues in OverviewPage.tsx, refactor-only:

• S4624 nested template → hoisted toneClass const
• S3776 cognitive complexity 18→≤15 → pure KPI/score/alert logic extracted to a sibling OverviewPage.kpis.ts module (matches the repo's fleetTypes/fleetFilters convention; also makes it unit-testable) + a RecentDecisionRow component
• S3735 void operator → replaced with the repo-native ignorePromise(...) idiom
• S6772 ambiguous JSX spacing → explicit {' '} in the <h1>

Tests (2-2): +23 meaningful cases (new OverviewPage.kpis.test.ts covering the extracted derivations' branches + window-toggle/hero/snapshot/recent-decisions in OverviewPage.test.tsx). Full suite 1326 pass; lint/type-check/build clean. No behaviour change.

Verdict: Scope-complete, correct, green, well-tested. Ready to approve & merge.