feat: add ctx.IsRoute for active-nav highlighting

[acoshift]

Summary

The final Tier-2 item. ctx.IsRoute(name) reports whether the named route is the most specific (deepest) registered route matching the current request path — for highlighting the active nav link.

return ctx.View("page", ctx) // pass ctx as the view data

<a href="{{route "users"}}" class="{{if .IsRoute "users"}}active{{end}}">Users</a>

Matching (best-match)

Routes Home=/, Admin=/admin, Users=/admin/users; on /admin/users/42:

IsRoute(...)	result
"users"	true (most specific)
"admin"	false (a deeper route matches)
"home"	false

• Path-segment aware: /admin matches /admin/x but not /administrators.
• / is active only on exactly /.
• A section (/admin) stays active on its sub-paths (/admin/settings) when no deeper route matches.
• A route's query string and trailing slash are normalized away (/docs/ behaves like /docs), via a small routePath helper.

Why a method, not a {{isRoute}} template func

A bare {{isRoute}} func can't see the request: hime's template funcs bind at parse time on the shared app.parent, and rebinding per request would force a template clone on every render (required for thread-safety) plus awkward nested-{{component}} handling. html/template already calls methods on the data, so a Context method used as {{.IsRoute "x"}} (pass ctx as the data) gives request-aware highlighting with zero clone, zero core-render change, thread-safe, and it works inside components too. Bonus: it makes .IsHTMX, .CookieValue, … usable from templates the same way.

Note

Best-match scans the route table per call (O(routes)) and couples a route's result to the whole table (registering a deeper route can change a shallower one's highlight) — that coupling is the intended "most specific wins" behavior. Negligible cost for realistic route tables.

Test plan

• go vet ./...
• go test ./... — 100% coverage on IsRoute, routePath, pathUnder; covers exact / sub-path / section / segment-aware / root / query / trailing-slash / panic cases, plus an in-template test (View("nav", ctx) → {{.IsRoute}})
• go test -race ./...
• gofmt clean
• runnable ExampleContext_IsRoute; CLAUDE.md updated

Completes Tier 2: signed cookies → flash → FormState → IsRoute.

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