fix(add): the playground builds the page's remote before running (#1230)

The backend answered 404 for /assets/mf-manifest.json — the manifest it
advertises in its own /.well-known/solution.json — so a host could
federate nothing and the page had no bundle to load.

The cause was not the address. The solution runtime serves /assets/ from
ASSETS_DIR, which already defaults to ../fe-remote/dist relative to the
backend; there was simply never a build there. The fleet's playground
runs its build-frontend.sh FIRST for exactly this reason, and the
scaffolded Makefile did not build the remote at all.

It now builds it and asserts the manifest exists before the run, so the
failure is a build error at the top rather than a 404 an hour later. The
shell installs the remote as a copy, so it needs it built too.

Verified on a clean scaffold:

    dist/mf-manifest.json                      1.7 kB
    backend /assets/mf-manifest.json           200
            {"id":"notes","exposes":["Page"]}
    edge    /                                  200  (signed in as alex)
    edge    /v1/notes/overview                 200

Co-authored-by: Antoine Toussaint <312536060+antoinetoussaint-byte@users.noreply.github.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: antoinetoussaint-byte

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: