[BunsDev]

What changed

The static routing demo could not save a TypeSafe key, report live usage, or compare an actual CLI host. Replace it with a Next.js App Router application while preserving the pure harness in src/ unchanged.

• Compact dashboard header with active-page underline tabs. Full-width dark React UI with routing, schema/context examples, and an Agent arena. Progressive disclosure keeps the main path focused on tools exposed → observed calls → answer.
• Playground-style masked personal-key override and reported Jev usage, with unknown usage kept distinct from zero. The loopback host rebuilds bounded, pinned-model requests and excludes credentials from receipts and logs.
• Two isolated Codex CLI lanes run concurrently after routing, with independent live activity, elapsed timers, cancellation, and results. Only fixed synthetic MCP handlers are permitted; proposed patches are never applied.
• A responsive, keyboard-navigable run inspector presents usage bars, tool timelines, Jev evidence, and the comparison setup. Raw receipts remain a deeper disclosure.

This is an explicitly requested example-host expansion. Dependencies were landed separately in #19/#8; this PR adds no dependency versions. Auth-only temporary CLI homes, read-only sandboxing, disabled external features, bounded inputs/output/time, and process-group cancellation stay in the host, outside the exported package.

Verdict impact

None. No src/ changes, verdict changes, decision-table changes, proposal-review question changes, or model-pin changes. The fixture host may read invented files and record proposals; it never executes model-proposed source.

Verification

• pnpm typecheck
• pnpm test — 72 offline tests, including parallel-start/settlement, CLI activity transitions, MCP bounds, origin normalization, and usage accounting.
• pnpm build — production build in an isolated copy of the final source so the requested dev preview remains available.
• pnpm check:secrets and signed commits; existing hooks remain enabled.
• 143 browser checks: responsive layouts, keys/usage, progressive disclosure, inspector keyboard controls, parallel progress, partial results, cancellation, and unknown usage. Provider requests were intercepted.
• Manual live parallel arena run through the UI: both lanes returned a real synthetic read_file call. Separate from automated tests; not a quality, cost, or latency benchmark.
• Fresh code review; findings addressed and regression-checked.

The template's no-provider/no-credential/no-execution-path checkbox does not apply to this requested optional local host: those additions are explicitly described above. No provider, React, or CLI I/O enters src/.

Review fixes: fixture contents now stay behind MCP rather than in the common prompt; pending proposals retain their bounded diff and rationale in the inspector/export; Windows CLI execution is explicitly refused before any process or auth workspace starts.

Limitations: the CLI host requires macOS or Linux; file-based Codex sign-in is required; keychain-only auth is unsupported. Browser key storage is origin-local and unencrypted, as disclosed in settings. Independent trajectories, cache effects, and shared host resources affect comparisons. Answer quality is not automatically scored. Human keyboard-only/VoiceOver acceptance and repeated live benchmarking remain outstanding.

[Copilot]

Copilot review overview

🔵 Needs a closer look

The credential-bearing provider path and concurrent Codex/MCP process sandbox have correctness and lifecycle findings requiring fixes and final human security review.

Review effort: Lite
Findings: 3 · 1

Open (4)

• Clean up MCP process trees on Windows cancellation · New
• Avoid embedding fixture contents outside the MCP tool context · New
• Persist propose_patch arguments in the trace · New
• Update stale verifier command from pnpm demo to pnpm dev · New

What changed in this PR

Replaces the static routing demo with a Next.js App Router host while preserving the pure harness in src/.

Changes:

• Adds live Jev routing, key storage, usage reporting, and responsive React UI.
• Adds a synthetic Codex CLI arena with parallel MCP lanes and inspectors.
• Updates tests, documentation, CI, and removes the old static demo host.

File	Description
tsconfig.json	Enables Next.js and React compilation.
tsconfig.demo.json	Removes obsolete demo configuration.
tests/​usage.test.ts	Tests usage parsing and accounting.
tests/​routing-demo.test.ts	Removes obsolete static-server tests.
tests/​routing-bench.test.ts	Adapts benchmark assertions.
tests/​live-host.test.ts	Tests live host validation and failures.
tests/​arena.test.ts	Tests MCP and CLI arena behavior.
scripts/​verify-live-browser.mjs	Adds live UI verification.
scripts/​verify-arena-browser.mjs	Adds arena UI verification.
scripts/​demo-routing.ts	Removes obsolete launcher.
scripts/​arena-mcp.mjs	Adds bounded synthetic MCP server.
README.md	Documents the new demo host.
public/​favicon.svg	Adds application favicon.
package.json	Adds Next.js development and build scripts.
next.config.ts	Configures Next.js aliases and security headers.
examples/​routing/​usage.ts	Implements session usage tracking.
examples/​routing/​server.ts	Removes obsolete static server.
examples/​routing/​live-client.ts	Adds browser live-routing client.
examples/​routing/​index.html	Removes obsolete static page.
examples/​routing/​demo-state.ts	Supports injected live routers.
examples/​routing/​compare.ts	Adds live measurements to comparisons.
examples/​routing/​browser.ts	Removes obsolete browser implementation.
examples/​routing/​api-key.ts	Implements local key storage.
examples/​host/​runtime.ts	Creates server-side live handler.
examples/​host/​live.ts	Adds bounded provider adapter.
examples/​host/​codex.ts	Runs isolated Codex CLI processes.
examples/​host/​arena-lanes.ts	Coordinates parallel arena lanes.
examples/​arena/​cases.ts	Defines synthetic arena fixtures.
docs/​verification/​next-browser-2026-09-22.json	Records browser verification.
docs/​verification/​live-routing-2026-09-22.json	Records live routing smoke test.
docs/​verification/​live-browser-2026-09-22.json	Records live UI checks.
docs/​verification/​live-arena-parallel-2026-09-22.json	Records parallel arena run.
docs/​verification/​live-arena-2026-09-22.json	Records arena smoke test.
docs/​routing-demo.md	Documents the new host and arena.
docs/​roadmap.md	Updates project milestones.
docs/​plans/​routing-demo.md	Tracks requested demo work.
docs/​architecture.md	Documents host boundaries.
components/​routing-room.tsx	Implements routing UI.
components/​header.tsx	Adds navigation, key, and usage controls.
components/​example-lab.tsx	Adds schema/context experiments.
components/​comparison.tsx	Displays routing accounting.
components/​arena.tsx	Implements arena orchestration UI.
components/​arena-results.tsx	Displays lane results and accounting.
components/​arena-inspector.tsx	Adds run inspection tabs.
app/​page.tsx	Defines routing page.
app/​layout.tsx	Defines shared application layout.
app/​globals.css	Styles the application UI.
app/​examples/​page.tsx	Defines examples page.
app/​arena/​page.tsx	Defines arena page.
app/​api/​route/​route.ts	Exposes live routing endpoint.
app/​api/​config/​route.ts	Exposes host configuration status.
app/​api/​arena/​route.ts	Streams arena execution events.
AGENTS.md	Adds host-specific safety guidance.
.gitignore	Ignores Next.js generated files.
.github/​workflows/​checks.yml	Adds production build verification.

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