refactor(ai-elements): migrate live event cards

[HomenShum]

What changed

• Migrates FastAgentPanel live tool activity onto the shared AI Elements Tool primitive.
• Adds a single typed projection from unified and legacy event streams with stable semantic IDs and deterministic collision suffixes.
• Preserves honest Pending/Running/Completed/Error/Denied states, including output-denied and lagging nonempty errorText precedence.
• Fails closed for unknown future unified states instead of falsely presenting them as running.
• Adds an accessible compact-sidebar Live Events opener on the canonical Cockpit path without duplicating the global overlay or streaming hook.
• Adds focused projection, card, denied/error, ID-stability, collision, and header reachability coverage.

Why

The previous custom card could not safely adopt the primitive while unified event states, legacy events, and compact sidebar reachability were mixed in the parent. Two rounds of independent review found and then verified fixes for stale error state, unstable IDs, lost denial semantics, and an unreachable canonical opener.

Validation

• Focused Live/Header/Tool/Input/UIMessage contracts: 77 passed
• Full FastAgentPanel: 203 passed, 19 environment-gated skipped
• Explicit streaming guard: 1 passed
• npx tsc --noEmit --pretty false
• Design system: 11 passed; npm run lint:design has 0 high findings
• npm run build
• Bundle guard: FastAgentPanel 1,558,184 B; separate code block 73,341 B; separate Streamdown 163,187 B; 0 Shiki/oniguruma/wasm markers in panel; 0 assets/shiki/ service-worker precache entries; no asset over 10 MiB
• Independent final P0/P1 audit: GO, no findings

Release

Ready for required checks and CI-gated squash auto-merge. No admin bypass.

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Project	Deployment	Actions	Updated (UTC)
nodebench-ai	Ready	Preview, Comment	Jul 14, 2026 12:30pm

[github-actions]

PR size advisory

This PR adds 1113 lines of substantive change. CONTRIBUTING.md defines a soft limit of ~400 LOC.

If the PR is genuinely cohesive (e.g. an architecture map, a generated migration, a deletion of a dead module), no action is needed. Otherwise consider:

• splitting into 2-3 PRs along independent concerns
• pre-discussing the architecture change in a GitHub Discussion before merge

This is advisory — it does not block the merge.

[github-actions]

✅ Dogfood Visual QA Gate: PASSED

Check	Status
Screenshots	23 captured (pass)
Walkthrough	9 chapters (pass)
Key Frames	9 extracted (pass)
Scribe Steps	8 how-to steps (pass)
Build	success

Artifacts

Download the dogfood-evidence-ed088fd artifact from the Actions tab for full screenshots, frames, and walkthrough video.

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Generated by Dogfood QA Gate

[github-actions]

Demo: walkthrough of the surfaces this PR changed is available as a workflow artifact (pr-demo-527) at https://github.com/HomenShum/NodeBenchAI/actions/runs/29333031603