Route templates: a route named x-* serves any request route x-<something>

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

internal/proxy/proxy.go

@@ -144,13 +144,13 @@ func (p *Handler) route(r *http.Request) (route, rest string, code int, msg stri
 	if hdr != "" {
 		rest := r.URL.Path
 		// A path that also carries a (different) route name is a client mistake: the header is the
-		// operator's intent, but the path disagrees.
+		// operator's intent, but the path disagrees. Compare concrete names.
 		if rname, _, ok := SplitRoute(rest); ok {
-			if _, known := p.cfg.Routes[rname]; known && rname != hdr {
+			if _, _, rok := p.cfg.Route(rname); rok && rname != hdr {
 				return "", "", http.StatusBadRequest, "conflicting route"
 			}
 		}
-		if _, known := p.cfg.Routes[hdr]; !known {
+		if _, _, ok := p.cfg.Route(hdr); !ok {
 			return "", "", http.StatusNotFound, "unknown route"
 		}
 		if !allowedPath(rest) {
@@ -162,7 +162,7 @@ func (p *Handler) route(r *http.Request) (route, rest string, code int, msg stri
 	if !ok {
 		return "", "", http.StatusBadRequest, "missing route"
 	}
-	if _, known := p.cfg.Routes[route]; !known {
+	if _, _, ok := p.cfg.Route(route); !ok {
 		return "", "", http.StatusNotFound, "unknown route"
 	}
 	if !allowedPath(rest) {
@@ -207,7 +207,7 @@ func (p *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		p.writeError(w, code, msg)
 		return
 	}
-	routeCfg := p.cfg.Routes[route]
+	routeCfg, _, _ := p.cfg.Route(route)
 
 	model, body, err := peekModel(r)
 	if err != nil {

internal/proxy/template_test.go

@@ -0,0 +1,85 @@
+package proxy_test
+
+import (
+	"net/http"
+	"testing"
+	"time"
+
+	"git.wntrmute.dev/kyle/crossbar/internal/proxy"
+	"git.wntrmute.dev/kyle/crossbar/internal/store"
+)
+
+const templateHosts = `
+listen = "127.0.0.1:1"
+[hosts.alpha]
+base_url = %q
+models = { "shared" = { parallel = 4 } }
+[routes."opencode-*"]
+hosts = ["alpha"]
+default_model = "shared"
+[routes.opencode-fixed]
+hosts = ["alpha"]
+default_model = "shared"
+`
+
+// One OpenCode instance per route, without listing every instance in the config: a route named
+// "opencode-*" serves any request route "opencode-<something>". Leases and accounting are keyed
+// by the concrete route name, so two instances never share a lease and each gets its own usage
+// row. The literal template name is never a request route.
+func TestRouteTemplateServesConcreteRoutes(t *testing.T) {
+	alpha := newUpstream(t, "alpha")
+	r := newRig(t, templateHosts, alpha)
+
+	resp := r.post("/opencode-projecta-4242/v1/chat/completions", conversation(1, 1))
+	drain(resp)
+	if resp.StatusCode != 200 || resp.Header.Get(proxy.HostHeader) != "alpha" || resp.Header.Get(proxy.LeaseHeader) != "new" {
+		t.Fatalf("first turn on a templated route: %d %q %q, want 200 alpha new", resp.StatusCode, resp.Header.Get(proxy.HostHeader), resp.Header.Get(proxy.LeaseHeader))
+	}
+	resp = r.post("/opencode-projecta-4242/v1/chat/completions", conversation(1, 2))
+	drain(resp)
+	if resp.Header.Get(proxy.LeaseHeader) != "reused" {
+		t.Errorf("second turn should reuse the lease, got %q", resp.Header.Get(proxy.LeaseHeader))
+	}
+	// A second instance with the same conversation shape is a different route: its own lease.
+	resp = r.post("/opencode-projectb-7/v1/chat/completions", conversation(1, 1))
+	drain(resp)
+	if resp.StatusCode != 200 || resp.Header.Get(proxy.LeaseHeader) != "new" {
+		t.Errorf("another instance must get its own lease: %d %q", resp.StatusCode, resp.Header.Get(proxy.LeaseHeader))
+	}
+	// The header form resolves templates too.
+	resp = r.post("/v1/chat/completions", conversation(2, 1), proxy.RouteHeader, "opencode-projectc-1")
+	drain(resp)
+	if resp.StatusCode != 200 {
+		t.Errorf("X-Crossbar-Route with a templated name: %d, want 200", resp.StatusCode)
+	}
+	// An exact route still works and is not shadowed by the template.
+	resp = r.post("/opencode-fixed/v1/chat/completions", conversation(3, 1))
+	drain(resp)
+	if resp.StatusCode != 200 {
+		t.Errorf("exact route: %d, want 200", resp.StatusCode)
+	}
+
+	for _, path := range []string{"/opencode-*/v1/models", "/opencode-/v1/models", "/opencode/v1/models", "/opencodex/v1/models"} {
+		req, _ := http.NewRequest(http.MethodGet, r.front.URL+path, nil)
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			t.Fatal(err)
+		}
+		drain(resp)
+		if resp.StatusCode != 404 {
+			t.Errorf("%s: %d, want 404 unknown route", path, resp.StatusCode)
+		}
+	}
+
+	rows, _ := r.store.Usage(time.Time{}, store.ByRoute)
+	keys := map[string]int64{}
+	for _, row := range rows {
+		keys[row.Key] = row.Requests
+	}
+	if keys["opencode-projecta-4242"] != 2 || keys["opencode-projectb-7"] != 1 || keys["opencode-projectc-1"] != 1 || keys["opencode-fixed"] != 1 {
+		t.Errorf("usage by route = %v, want rows per concrete route", keys)
+	}
+	if _, present := keys["opencode-*"]; present {
+		t.Errorf("the template name must never be an accounting key: %v", keys)
+	}
+}