Routes may share one lease (affinity = "route") and skip crossbar's queue (queue = false)

route.go gains Route.Affinity/Queue with PerRoute(), Queues() and affinity
validation (checkRoutes moved here; config.go calls it once). limiter.Track
counts a request without holding or refusing it; a release hands the slot to a
waiter only while in flight <= parallel. The proxy leases a PerRoute() route
under an empty fingerprint (the row keeps the real one) and uses Track when
Queues() is false.

Implemented by Ornith (OpenCode); owner review removed a release-on-first-flush
workaround for a race in the owner's given test (see implementer log).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/config/route.go

@@ -1,13 +1,41 @@
 package config
 
 import (
+	"fmt"
 	"regexp"
+	"sort"
 	"strings"
 )
 
 // templateName matches a route template: a valid route name ending in "-*".
 var templateName = regexp.MustCompile(`^[a-z0-9][a-z0-9-]*-\*$`)
 
+// routeName matches a route (or template) name: the pattern a concrete or template route key must
+// match, so a name with '*' or an invalid prefix never resolves.
+var routeName = regexp.MustCompile(`^[a-z0-9][a-z0-9-]*$`)
+
+// Route is an ordered list of hosts to try, with an optional default model, the peers allowed to
+// reach it, how its requests are placed (affinity), and whether crossbar queues them.
+type Route struct {
+	Hosts        []string `toml:"hosts"`
+	DefaultModel string   `toml:"default_model"`
+	Peers        []string `toml:"peers"`
+	Affinity     string   `toml:"affinity"` // "" or "conversation" (the default), or "route"
+	Queue        *bool    `toml:"queue"`    // nil means true
+}
+
+// PerRoute reports affinity = "route": every request on the route (chat or control) shares one
+// lease per model, so the route lives on one host.
+func (r Route) PerRoute() bool {
+	return r.Affinity == "route"
+}
+
+// Queues reports whether the route's requests wait in (and can be refused by) crossbar's per-(host,
+// model) queue; false only for queue = false, which leaves queueing to the client's own slot.
+func (r Route) Queues() bool {
+	return r.Queue == nil || *r.Queue
+}
+
 // Route resolves a request route name: an exact entry wins; else the longest template
 // "<prefix>-*" whose prefix (including the dash) starts name with a non-empty remainder;
 // else ok is false. key is the config key that matched (the template's name for a template).
@@ -38,3 +66,64 @@ func (c *Config) Route(name string) (r Route, key string, ok bool) {
 	}
 	return best, bestKey, true
 }
+
+// checkRoutes validates and defaults one route's hosts, model, affinity and peers in a fixed order.
+// A name that is neither a valid route nor a template, a missing or unknown host, a default model no
+// host serves, an unrecognised affinity, or a peers list that breaks the identity contract each
+// wins as the first error.
+func (c *Config) checkRoutes(peersDefined map[string]bool, identityDefined bool) *Error {
+	if len(c.Routes) == 0 {
+		return &Error{Field: "routes", Msg: "at least one required"}
+	}
+	names := make([]string, 0, len(c.Routes))
+	for name := range c.Routes {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+	for _, name := range names {
+		r := c.Routes[name]
+
+		if !routeName.MatchString(name) && !templateName.MatchString(name) {
+			return &Error{Field: fmt.Sprintf("routes.%s", name), Msg: "must match [a-z0-9][a-z0-9-]*"}
+		}
+
+		hostsField := fmt.Sprintf("routes.%s.hosts", name)
+		if len(r.Hosts) == 0 {
+			return &Error{Field: hostsField, Msg: "at least one required"}
+		}
+		seen := make(map[string]bool, len(r.Hosts))
+		for _, h := range r.Hosts {
+			if seen[h] {
+				return &Error{Field: hostsField, Msg: "host listed twice"}
+			}
+			seen[h] = true
+			if _, ok := c.Hosts[h]; !ok {
+				return &Error{Field: hostsField, Msg: "unknown host"}
+			}
+		}
+
+		if r.DefaultModel != "" {
+			served := false
+			for _, h := range r.Hosts {
+				if _, ok := c.Hosts[h].Models[r.DefaultModel]; ok {
+					served = true
+					break
+				}
+			}
+			if !served {
+				return &Error{Field: fmt.Sprintf("routes.%s.default_model", name), Msg: "not served by any host in route"}
+			}
+		}
+
+		switch r.Affinity {
+		case "", "conversation", "route":
+		default:
+			return &Error{Field: fmt.Sprintf("routes.%s.affinity", name), Msg: `must be "conversation" or "route"`}
+		}
+
+		if e := checkPeers(name, r.Peers, peersDefined[name], identityDefined, c.Identity); e != nil {
+			return e
+		}
+	}
+	return nil
+}