fix(qwen): un-exempt opencode, and keep the Qwen key in a secret

Two findings this round contradicted each other — one asked me to extend the
engine-spec exemption to a bare "opencode", the other said opencode should not
be exempt at all. The code settles it: that engine drives an ollama-cloud model
through the bundled CLI and authenticates with OLLAMA_API_KEY, so it needs
exactly the key the pre-flight checks. Exempting it, which I did last round,
switched the check off for the one engine it could still help. Only claude-code
is exempt now — it carries CLAUDE_CODE_OAUTH_TOKEN and needs no Ollama key —
and opencode/open-code get table rows so both spellings are covered.

The README told operators to embed the Qwen key in a GADFLY_ENDPOINT_* var,
while the workflow that forwards those vars warns in its own comments that vars
are NOT masked. Rather than only rewording the docs, a keyless kimi/qwen
endpoint now falls back to its own QWEN_API_KEY / KIMI_API_KEY — the same
vendor's key, so the no-cross-vendor rule is untouched — which lets the URL live
in a var and the credential in a secret. Break-checked by pointing that fallback
at OPENAI_API_KEY: the leak test catches it.

Smaller: isBuiltinCompatProvider mirrors isOpenAICompatProvider instead of an
inline slices.Contains, with a test that every builtin is also in the compat
list (a builtin missing from it would never reach the branch that protects it);
the preflight.sh rationale is stated once rather than in two comment blocks;
the Go test locates the shell script relative to its own source file; and the
gofmt step takes GOPROXY=off like its neighbours.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

cmd/gadfly/model.go

@@ -44,6 +44,19 @@ func isOpenAICompatProvider(name string) bool {
 	return slices.Contains(openAICompatProviders, name)
 }
 
+// isBuiltinCompatProvider mirrors isOpenAICompatProvider rather than testing
+// the slice inline, so both memberships are asked the same way.
+func isBuiltinCompatProvider(name string) bool {
+	return slices.Contains(builtinCompatProviders, name)
+}
+
+// builtinCompatKeyEnv is the provider's own credential variable, matching the
+// name majordomo's built-in reads on the registry path — so the same secret
+// works whether or not an explicit endpoint is configured.
+func builtinCompatKeyEnv(provider string) string {
+	return strings.ToUpper(strings.ReplaceAll(provider, "-", "_")) + "_API_KEY"
+}
+
 // openAICompatOptions builds the option set for an openai-compat provider, and
 // is the ONE place the no-cross-vendor-fallback rule lives.
 //
@@ -55,7 +68,17 @@ func isOpenAICompatProvider(name string) bool {
 func openAICompatOptions(provider, baseURL, key, keyHint string) []openai.Option {
 	opts := []openai.Option{openai.WithBaseURL(baseURL)}
 	switch {
-	case slices.Contains(builtinCompatProviders, provider):
+	case isBuiltinCompatProvider(provider):
+		// With no explicit key, fall back to the provider's OWN variable
+		// (QWEN_API_KEY, KIMI_API_KEY). That is not the cross-vendor fallback
+		// this function exists to prevent — it is the same vendor's key — and
+		// it lets an operator keep the credential in a masked secret while the
+		// endpoint URL lives in a var, which is NOT masked.
+		if key == "" {
+			if own := os.Getenv(builtinCompatKeyEnv(provider)); own != "" {
+				key, keyHint = own, builtinCompatKeyEnv(provider)
+			}
+		}
 		opts = append(opts, openai.WithAPIKey(key), openai.WithAPIKeyName(keyHint))
 	case key != "":
 		opts = append(opts, openai.WithAPIKey(key))

cmd/gadfly/model_test.go

@@ -6,6 +6,7 @@ import (
 	"net/http/httptest"
 	"os/exec"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 
@@ -185,7 +186,13 @@ func TestOpenAICompatProvidersAreFullyWired(t *testing.T) {
 		advertised[strings.TrimSpace(n)] = true
 	}
 
-	script := filepath.Join("..", "..", "scripts", "preflight.sh")
+	// Locate the script relative to THIS source file rather than the working
+	// directory, so moving the package does not silently break the lookup.
+	_, thisFile, _, ok := runtime.Caller(0)
+	if !ok {
+		t.Fatal("runtime.Caller failed; cannot locate scripts/preflight.sh")
+	}
+	script := filepath.Join(filepath.Dir(thisFile), "..", "..", "scripts", "preflight.sh")
 	out, err := exec.Command("bash", "-c", ". "+script+"; gadfly_preflight_providers").Output()
 	if err != nil {
 		t.Fatalf("query gadfly_preflight_providers from %s: %v", script, err)
@@ -317,3 +324,52 @@ func assertFailsClosed(t *testing.T, m llm.Model, seen *[]string, foreign, wantH
 		t.Errorf("error = %v, want it to name %s so the operator knows what to set", err, wantHint)
 	}
 }
+
+// TestBuiltinCompatOwnKeyFallback: with no key in the endpoint definition, a
+// built-in falls back to its OWN variable (QWEN_API_KEY, KIMI_API_KEY) — never
+// to another vendor's. This is what lets the credential live in a masked
+// secret while the endpoint URL lives in a GADFLY_ENDPOINT_* var, which Gitea
+// does not mask; the README used to advise embedding the key in that var.
+func TestBuiltinCompatOwnKeyFallback(t *testing.T) {
+	const own, foreign = "sk-qwen-own", "sk-openai-must-not-travel"
+
+	srv, seen := leakServer(t)
+	t.Setenv("OPENAI_API_KEY", foreign)
+	t.Setenv("QWEN_API_KEY", own)
+
+	p, err := endpointProvider("ep", "qwen|"+srv.URL+"/v1") // no key field
+	if err != nil {
+		t.Fatalf("endpointProvider: %v", err)
+	}
+	m, err := p.Model("some-model")
+	if err != nil {
+		t.Fatalf("Model: %v", err)
+	}
+	if _, err := m.Generate(context.Background(), llm.Request{Messages: []llm.Message{llm.UserText("hi")}}); err != nil {
+		t.Fatalf("Generate: %v", err)
+	}
+	if len(*seen) == 0 {
+		t.Fatal("no request reached the server — the own-key fallback did not take effect")
+	}
+	for _, auth := range *seen {
+		if strings.Contains(auth, foreign) {
+			t.Errorf("Authorization carried the OpenAI key: %q", auth)
+		}
+		if !strings.Contains(auth, own) {
+			t.Errorf("Authorization = %q, want the provider's own QWEN_API_KEY", auth)
+		}
+	}
+}
+
+// TestBuiltinCompatProvidersAreOpenAICompat: the two slices are parallel, and a
+// built-in missing from openAICompatProviders would never reach the branch that
+// applies its unconditional-key rule — it would fall through to the generic
+// switch and silently lose the protection.
+func TestBuiltinCompatProvidersAreOpenAICompat(t *testing.T) {
+	for _, p := range builtinCompatProviders {
+		if !isOpenAICompatProvider(p) {
+			t.Errorf("%q is in builtinCompatProviders but not openAICompatProviders, so the "+
+				"no-cross-vendor-fallback branch never runs for it", p)
+		}
+	}
+}