[P2] frontend: Finish ADR-007 tooling modernization

[Cataldir]

Problem inventory

The frontend has made partial modernization progress but still drifts from the accepted ADR-007 target stack.

Type: tech debt / modernization drift

Evidence

• frontend/package.json uses next 15.5.10 and pnpm, but still uses react/react-dom 18.3.1, @types/react 18, TypeScript 5.6.3, Tailwind 3.4.14, ESLint 8, and Zustand 4.
• ADR-007 targets React 19, TypeScript 5.7+, Tailwind 4, ESLint 9, and Zustand 5.
• frontend/package-lock.json still exists and contains stale Next 14-era lock data while pnpm-lock.yaml is the declared package manager lockfile.

Impact assessment

User impact: medium/high. Tooling drift slows feature delivery and makes design modernization riskier, especially once Playwright and React 19 behavior are introduced.
Blast radius: frontend dependency graph, build pipeline, styling tokens, React hydration/runtime behavior, and CI reproducibility.

Acceptance criteria

• Decide whether ADR-007 still targets React 19/Tailwind 4 immediately or needs an explicit phased migration note; document the decision.
• Upgrade React, React DOM, TypeScript, Tailwind, ESLint/Biome-adjacent tooling, Zustand, and type packages according to the chosen migration path.
• Remove stale package-lock.json if pnpm is the only supported package manager, or document why dual locks are intentionally retained.
• Fix any React 19, Tailwind 4, or strict TypeScript regressions introduced by the upgrade.
• pnpm --dir frontend install, lint, and build pass on Node 22.
• Update frontend README and modernization documentation if commands or requirements change.

Agent assignment

Primary specialist: TypeScriptDeveloper
Supporting specialist: PlatformEngineer

Dependency notes

Can run in parallel with design inventory, but should avoid broad UI rewrites until the route/functionality map is stable.

Related backlog

• ADR-007 is the primary source of truth for the target stack.

[Cataldir]

Delegation status

Primary specialist: PlatformEngineer
Supporting specialist: TypeScriptDeveloper
UI/accessibility validation: UIDesigner
Status: delegated; implementation not started.

Platform findings:

• No Playwright config/scripts exist today.
• Default PR E2E should use mocked APIM fixtures via NEXT_PUBLIC_APIM_BASE_URL; live APIM tests should be tagged/manual until contracts are stable.
• Browser smoke should cover public routes, role workspace routes, primary nav, redirects, and core APIM-backed flows.
• Accessibility checks should combine axe with explicit keyboard/focus/status/reflow assertions; automation alone is not a WCAG conformance claim.

Next PR slice:

1. Clean package-manager/tooling drift under chore(deps-dev): bump postcss from 8.4.35 to 8.5.10 in /frontend #225.
2. Add Playwright config, scripts, mocked APIM fixtures, and public/workspace smoke tests.
3. Add SWA frontend quality gate before deploy upload.

[Cataldir]

Correction and delegation status

A previous comment on this issue referenced E2E coverage and was intended for #223. This issue is the canonical tooling modernization issue.

Primary specialist: TypeScriptDeveloper
Supporting specialist: PlatformEngineer
Status: delegated; implementation not started.

Tooling findings:

• Use a phased ADR-007 migration; do not combine React 19, Tailwind 4, and route feature work in one PR.
• Next.js is already 15.5.10, but React/React DOM remain 18, Tailwind remains 3, TypeScript is 5.6, Zustand is 4, and package-lock.json is stale npm drift.

Next PR slice:

1. Make pnpm the only package-manager artifact and remove/document package-lock drift.
2. Upgrade low-risk tooling first: TypeScript 5.7+ and @types/node 22.
3. Verify pnpm install, lint, and build on Node 22.
4. Split React 19 and Tailwind 4 into later dedicated PRs.

[Cataldir]

Correction and delegation status

A previous comment on this issue referenced E2E coverage and was intended for #223. This issue is the canonical tooling modernization issue.

Primary specialist: TypeScriptDeveloper
Supporting specialist: PlatformEngineer
Status: delegated; implementation not started.

Tooling findings:

• Use a phased ADR-007 migration; do not combine React 19, Tailwind 4, and route feature work in one PR.
• Next.js is already 15.5.10, but React/React DOM remain 18, Tailwind remains 3, TypeScript is 5.6, Zustand is 4, and package-lock.json is stale npm drift.

Next PR slice:

1. Make pnpm the only package-manager artifact and remove/document package-lock drift.
2. Upgrade low-risk tooling first: TypeScript 5.7+ and @types/node 22.
3. Verify pnpm install, lint, and build on Node 22.
4. Split React 19 and Tailwind 4 into later dedicated PRs.