Agentic payments demo + swap visualization + installable PWA

[Pattermesh]

Makes SWITCHBOARD demo-ready for agentic payments, adds a focused UI visualization, and ships an installable PWA with a plugin proposal. All additive; the existing lab and tests are untouched.

(1) Agentic payments demo — examples/agentic_demo/

A runnable scenario where Agent A pays Agent B for work via the x402 middleware + on-chain escrow, then Agent B routes the received token through SafeSwap.

Flow: 402 offer -> validate (cap/allowlist/gas budget) -> lock in escrow -> deliver -> confirm/release -> SafeSwap quote -> execute.

• Drives the real switchboard.x402_middleware.X402Middleware + switchboard.gas_tracker.GasTracker against an in-memory chain (MockChain / MockPaymentClient) that implements the PaymentClient + AgentEscrow surface — so it runs node/RPC-free.
• safeswap.py is a SafeSwapClient against the orchestrator API (/v1/quote, /v1/execute) with an in-process MockSafeSwapOrchestrator. Point SafeSwapClient(base_url=...) at the live orchestrator for real routing.
• Run it:

  PYTHONPATH=. python examples/agentic_demo/run.py
  PYTHONPATH=. python examples/agentic_demo/run.py --swap-to LUX --price 8 --json

• tests/test_agentic_demo.py asserts the full flow: the 402 offer carries the escrow scheme + price, the escrow ends Released (not just Locked), funds move payer -> escrow -> payee, the SafeSwap orchestrator is genuinely called (quote then execute), and the swap routes.

Note: X402Middleware._validate_offer calls gas_tracker.can_send_transaction(wallet, amount) but the stdlib GasTracker takes a single arg and is a process singleton. The demo wraps it in a small BudgetGuard adapter (and reset_all()s the singleton) rather than changing shared middleware behavior — see scenario.py.

(2) UI — web/lab/swap.html

A new lab page that visualizes the A2A pay + swap demo: an animated canvas (payer / escrow / payee / SafeSwap nodes with in-flight packets), a step-by-step flow ledger, and live balances, with swap-into / job-price controls. Reuses the lab's shared.css / shared.js and the Luxury-Observatory aesthetic. Wired into the lab dashboard, sidebar, and _build.js. The strict agents-demo.html scene engine is not touched.

(3) PWA — web/manifest.json + web/sw.js + docs/PWA.md

• Installable + offline-capable: manifest (standalone, icons any+maskable, shortcuts), service worker (app-shell precache, network-first navigations with offline fallback, stale-while-revalidate assets, cross-origin font cache).
• Registration injected via shared.js (every lab page) and web/index.html (root, scope ./).
• docs/PWA.md proposes the "switchboard plugin" PWA: install/consent flow, offline architecture, and how a host PWA embeds switchboard payments (402 interception -> budget-gated pay -> retry with proof, optional SafeSwap rebalance), reusing the same wire types as the Python library.
• tests/test_pwa.py validates the manifest + icons + start_url/shortcut targets, that sw.js is valid JS precaching a real on-disk shell with an offline fallback, and that registration is wired into root + lab pages. swap.html JS is node --checked too.

Gate

PYTHONPATH=. python3 -m pytest -q
245 passed, 62 skipped, 6 subtests passed

(baseline was 223 passed; +22 new tests across the demo + PWA). swap.html and sw.js pass node --check.

🤖 Generated with Claude Code

[abhicris]

🤖 Audit skipped — diff is 96KB (limit 64KB). Labelling for human review.