docs(routes): tighten the outage comments and notes

Shorter comments, changelog and CURRENT-STATE text for the 502 outage
path; the CURRENT-STATE paragraph now also names the 429 exception and
which budget expiry answers busy and which answers 502. Text only.

src/layers/directions/source.js

@@ -21,7 +21,7 @@ export function createDirectionsSource({
         signal,
         headers: { Accept: 'application/json' },
       });
-      // A failure page in front of the proxy need not be JSON.
+      // Proxy error pages may not be JSON.
       let payload = null;
       try {
         payload = await response.json();
@@ -45,8 +45,7 @@ export function createDirectionsSource({
           { status: 429, refusal },
         );
       }
-      // A 5xx is a routing outage whatever its body says; only the proxy's
-      // refusals carry an error text worth showing.
+      // A 5xx body may mislabel an outage as a route refusal.
       if (response.status >= 500 || (!response.ok && !payload?.error))
         throw Object.assign(
           new Error(`Routing unavailable (HTTP ${response.status})`),

src/tooling/placeProviders.test.mjs

@@ -236,7 +236,6 @@ test('OSRM routing preserves aliases, cache, span guards and upstream failure be
     assert.equal((await request(route, url)).body.error, error);
   assert.equal(calls, 1);
   now += 600001;
-  // OSRM's own "no route" is a 400 with a JSON code, and stays one.
   t.mock.method(globalThis, 'fetch', async () =>
     Response.json(
       { code: 'NoRoute', message: 'Impossible route between points' },

src/tools/places.js

@@ -189,8 +189,7 @@ export function createRouteService({
       } catch {
         /* the status below is authoritative */
       }
-      // A rate limit or an outage (5xx) is the routing service's failure, not
-      // a missing route, whatever the body says. Voice hears this message.
+      // Handle 429 and 5xx before route refusals, regardless of the body.
       if (response.status === 429) throw httpFailure(response, 'Routing');
       if (response.status >= 500)
         throw new ToolError(

src/tools/queries/places.test.mjs

@@ -283,7 +283,7 @@ test('a routing outage is reported as unavailable, not as invalid arguments', as
     assert.equal(result.structuredContent.error, 'unavailable');
     assert.doesNotMatch(result.content[0].text, /No walk route/);
   }
-  // Voice passes only the message on, so it names the outage itself.
+  // Voice receives only the message, so it must name the outage.
   const outage = createRouteService({
     fetchImpl: async () =>
       Response.json(