fix(add): the playground builds the page's remote before running

cmd/add/solution_playground.go

@@ -191,7 +191,7 @@ FRONTEND=${endpoint:%s/web/http}
 // playgroundMakefile writes the run line, whose one non-obvious part is that
 // authority/edge is NAMED. Nothing starts it otherwise.
 func playgroundMakefile(name string) string {
-	return fmt.Sprintf(`.PHONY: playground
+	return fmt.Sprintf(`.PHONY: playground remote
 
 # %s on the development authority, as a solution runs in a cell with no saas
 # host: the authority's edge is the one origin the browser opens and signs a
@@ -204,8 +204,19 @@ func playgroundMakefile(name string) string {
 # origin that can sign anyone in.
 PLAYGROUND_SERVICES = authority/edge %s/web %s/backend
 
-playground:
+# THE REMOTE IS BUILT FIRST, and that is not a convenience. The solution
+# runtime serves /assets/ from ASSETS_DIR, which defaults to
+# ../fe-remote/dist relative to the backend — so with no build there, the
+# backend answers 404 for /assets/mf-manifest.json, the manifest it
+# advertises in /.well-known/solution.json, and a host can federate nothing.
+# The shell also installs the remote as a copy, so it needs it built.
+playground: remote
 	cd %s && codefly run service $(PLAYGROUND_SERVICES) --env local
+
+.PHONY: remote
+remote:
+	cd services/fe-remote && npm install --no-audit --no-fund && npm run build
+	test -f services/fe-remote/dist/mf-manifest.json
 `, titleFromName(name), name, name, playgroundDir)
 }
 

cmd/add/solution_test.go

@@ -555,3 +555,25 @@ func TestTheContractDeclaresARoleBesidesInstaller(t *testing.T) {
 		t.Fatalf("the contract must declare installer and viewer, got %v", names)
 	}
 }
+
+// TestThePlaygroundBuildsTheRemoteFirst. The solution runtime serves /assets/
+// from ASSETS_DIR, which defaults to ../fe-remote/dist relative to the
+// backend. With nothing built there the backend answers 404 for
+// /assets/mf-manifest.json — the manifest it advertises in
+// /.well-known/solution.json — and a host can federate nothing. The fleet's
+// own playground builds the remote before the run for exactly this reason.
+func TestThePlaygroundBuildsTheRemoteFirst(t *testing.T) {
+	makefile := playgroundMakefile("notes")
+	if !strings.Contains(makefile, "playground: remote") {
+		t.Fatalf("the playground must build the remote first:\n%s", makefile)
+	}
+	for _, required := range []string{
+		"cd services/fe-remote && npm install",
+		"npm run build",
+		"test -f services/fe-remote/dist/mf-manifest.json",
+	} {
+		if !strings.Contains(makefile, required) {
+			t.Fatalf("the remote target must contain %q", required)
+		}
+	}
+}

docs/commands.md

@@ -2435,8 +2435,9 @@ What it creates:
 `services/fe-remote` — the `./Page` remote itself — is written by the solution
 agent, not by this command: it is an npm package, not a Codefly service.
 
-**Running it.** `make playground` starts the development authority and this
-solution, and prints the one address a browser opens:
+**Running it.** `make playground` builds the page's remote, starts the
+development authority and this solution, and prints the one address a browser
+opens:
 
 ```
 edge listening on :14581, routing 1 module(s)
@@ -2450,6 +2451,12 @@ not behind its sign-in edge") and the authority's REST port (every browser
 path 404s). In a cell the host's gateway plays the edge's part; the playground
 is local only.
 
+The remote is built **before** the run, and that is load-bearing: the solution
+runtime serves `/assets/` from `ASSETS_DIR`, which defaults to
+`../fe-remote/dist` relative to the backend. With nothing built there the
+backend answers 404 for `/assets/mf-manifest.json` — the manifest it
+advertises in `/.well-known/solution.json` — and a host can federate nothing.
+
 Sign in as any of the fixture's acme people in a team — `maya`, `remi`,
 `alex`, `dev` — and the solution's route answers: