feat: persist AI analysis with Vercel Workflow DevKit

[sergical]

Summary

• Extract analysis orchestration into a durable workflow (workflows/analysis.ts) using DurableAgent from @workflow/ai — survives navigation, hard refreshes, and server restarts
• Replace DefaultChatTransport with WorkflowChatTransport for automatic stream reconnection via localStorage run ID persistence
• Convert internal <a> tags to <Link> for client-side navigation (CoreWebVitalsSection, VitalsReport, DemoHeader)
• Fix "Analyze another" reset to clear workflow state and use router.push instead of window.location.reload()

Regression fixes

• Upgrade web-vitals to 5.1.0-soft-navs-2 with reportSoftNavs: true so metrics re-fire on soft navigations
• Remove onChatEnd callback that cleared the run ID — workflow now persists across soft navigation round-trips
• Widen loading UI condition to include "submitted" status so loading facts appear immediately when starting a scan

Test plan

• Start analysis → loading facts should appear immediately (not blank)
• After analysis completes → click vital metric link → soft nav, web-vitals report updates
• From vital page → click "Home" → workflow results still visible
• "Analyze another" → clean state, ready for new scan
• Hard refresh during streaming → should reconnect to in-flight workflow
• Follow-up suggestions still work after initial analysis
• npx workflow web — inspect workflow runs in the WDK dashboard
• Verify Sentry spans/metrics still fire (domain, outcome, duration)

🤖 Generated with Claude Code

[vercel]

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Project	Deployment	Actions	Updated (UTC)
webvitals-com	Ready	Preview, Comment	Feb 17, 2026 5:03pm
webvitals.com	Ready	Preview, Comment	Feb 17, 2026 5:03pm

[sentry]

Bug: In Safari private mode, localStorage.removeItem() fails silently. The subsequent hard navigation with window.location.href causes the old run ID to persist, resuming the previous workflow.
_{Severity: HIGH}

Suggested Fix

Replace the hard navigation window.location.href = "/" with a soft navigation, for example using Next.js's router.push("/"). This would allow the in-memory state to be reset correctly without relying on localStorage clearing, which is unreliable in private browsing modes. Alternatively, implement a more robust reset mechanism that doesn't depend on localStorage.removeItem() succeeding before navigation.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: components/ChatInterface.tsx#L47-L48

Potential issue: When a user in Safari's private browsing mode clicks "Analyze another",
the `handleReset` function attempts to clear the session by calling
`localStorage.removeItem("webvitals-run-id")`. This operation fails silently in Safari's
private mode. The code then performs a hard page navigation via `window.location.href =
"/"`. Upon reload, the application reads the stale `activeRunId` from `localStorage`,
which was never removed, and incorrectly calls `resumeStream()` to continue the previous
analysis workflow instead of initiating a new one. This prevents affected users from
starting a new analysis.

[sergical]

Not a real issue. Safari's private browsing mode has supported localStorage since Safari 11 (2017). The old behavior where localStorage.setItem() threw in private mode was removed years ago. In modern Safari private browsing, localStorage
works normally — it's just scoped to the session and cleared when the window closes.

The try/catch is already defensive enough for any truly exotic edge case. The removeItem call won't fail silently — it'll work fine or get caught.