[espetro]

Summary

app.route("/", sub) registered the sub-router's paths with a doubled slash (//health), so every root-mounted route fell through to the catch-all and 404'd. This PR normalizes a "/" prefix to "" in route() before mounting, matching Hono's app.route("/", sub) behavior.

Closes #97

Root cause

mountRoutes concatenates prefix and sub-path verbatim (packages/router/src/index.ts):

let path = String(prefix) + a;   // prefix "/" + "/health" => "//health"
if (path === "") {
  path = "/";
}

The path === "" guard only covers the empty-prefix case. In route(), the trailing-slash strip is gated on p.length > 1, so a lone "/" prefix survived verbatim and fell through to //health for every root-mounted route.

Repro

import { createRouter } from "@chttp/router";

const sub = createRouter();
sub.get("/health", (c) => c.text("ok"));

const app = createRouter();
app.route("/", sub);
await app.fetch(new Request("http://t/health"));   // 404 pre-fix — registered as "//health"

Pre-fix the repro prints 404; post-fix 200. app.route("", sub) worked before and is unchanged.

The fix

In route(), collapse "/" to "" ahead of the existing trailing-slash strip:

let p = String(prefix);
if (p === "/") {
  p = "";
} else if (p.length > 1 && p.charAt(p.length - 1) === "/") {
  p = String(p.slice(0, p.length - 1));
}

mountRoutes' empty-path guard then turns "" + "" into "/" for root handlers, and route("/api", sub) / route("", sub) behavior is untouched. The change stays inside the scriptc compilable subset (string equality + slice, same primitives as the existing strip); scripts/scriptc-gate.sh still reports 100% static coverage on all gates.

Tests

Added to packages/router/test/router.test.js (tests written first; the three root-mount cases fail pre-fix):

1. route("/", sub) resolves a sub-route (/health → handler runs, 200).
2. route("/", sub) resolves a handler registered at "/" in the sub-app (/ → 200).
3. Param preservation through the root mount (/item/:id).
4. route("/api", sub) still mounts under the prefix (no regression).

pnpm --filter @chttp/router build && pnpm --filter @chttp/router test: 105/105 pass. Full workspace pnpm -r test: all packages and examples pass, 0 failures.

Context

Found while porting Brioso's web API (briosoco/brioso#859) from Hono to chttp: miscApp mounts at the root and its /health, /ready, /robots.txt, /sitemap.xml routes all 404'd because of this bug.

Changeset

.changeset/router-root-mount.md — @chttp/router patch intent; pnpm change check passes.

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