diff --git a/.gitea/workflows/build-image.yml b/.gitea/workflows/build-image.yml
index b341cc9..ff62f3a 100644
--- a/.gitea/workflows/build-image.yml
+++ b/.gitea/workflows/build-image.yml
@@ -135,6 +135,7 @@ jobs:
         env: { GOPROXY: "off" }
         run: go vet ./...
       - name: gofmt
+        env: { GOPROXY: "off" }
         run: test -z "$(gofmt -l .)" || { gofmt -l .; exit 1; }
       - name: go test
         env: { GOPROXY: "off" }
diff --git a/README.md b/README.md
index 1592557..d76a175 100644
--- a/README.md
+++ b/README.md
@@ -95,10 +95,16 @@ default swarm, which is Ollama Cloud and keyed by `OLLAMA_CLOUD_API_KEY`.
 > host; point at your own with a named endpoint, which needs no code change:
 >
 > ```
-> GADFLY_ENDPOINT_QWENWS = "qwen|https://<workspace>.ap-southeast-1.maas.aliyuncs.com/compatible-mode/v1|<key>"
+> GADFLY_ENDPOINT_QWENWS = "qwen|https://<workspace>.ap-southeast-1.maas.aliyuncs.com/compatible-mode/v1"
 > GADFLY_MODELS          = "qwenws/qwen3.8-max,..."
+> QWEN_API_KEY           = <secret>
 > ```
 >
+> **Leave the key out of the endpoint var.** `GADFLY_ENDPOINT_*` are Gitea
+> *variables*, which are not masked in logs; the third `|<key>` field would put
+> a credential there. Omit it and a `qwen`/`kimi` endpoint falls back to its own
+> `QWEN_API_KEY` / `KIMI_API_KEY` secret — its own vendor's key, never another's.
+>
 > (Verified the hard way against a live deployment.)
 
 > ### 🧪 Honest status
diff --git a/cmd/gadfly/model.go b/cmd/gadfly/model.go
index 3589fb8..8dbd281 100644
--- a/cmd/gadfly/model.go
+++ b/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))
diff --git a/cmd/gadfly/model_test.go b/cmd/gadfly/model_test.go
index 1ebf2ab..43db0ef 100644
--- a/cmd/gadfly/model_test.go
+++ b/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)
+		}
+	}
+}
diff --git a/scripts/preflight.sh b/scripts/preflight.sh
index e250611..08f2312 100755
--- a/scripts/preflight.sh
+++ b/scripts/preflight.sh
@@ -26,12 +26,18 @@
 gadfly_preflight_key() {
   local provider="$1" model="${2:-}" key_env="" key_hint=""
 
-  # Engine specs are not majordomo providers and carry their own auth. A bare
-  # "claude-code" has no "/" so the caller's provider falls back to
-  # ollama-cloud, which would skip a reviewer that authenticates with
-  # CLAUDE_CODE_OAUTH_TOKEN and needs no Ollama key at all.
+  # claude-code carries its OWN auth (CLAUDE_CODE_OAUTH_TOKEN, else
+  # ANTHROPIC_API_KEY) and needs no Ollama key. A bare "claude-code" has no "/",
+  # so the caller's provider falls back to ollama-cloud and the table below
+  # would skip a perfectly configured reviewer.
+  #
+  # opencode is deliberately NOT exempt: that engine drives an ollama-cloud
+  # model through the bundled CLI and authenticates with OLLAMA_API_KEY, so it
+  # needs exactly the key the table checks. Exempting it — which an earlier
+  # version of this guard did — turns the pre-flight off for the one engine
+  # whose missing key it could still catch.
   case "$model" in
-    claude-code|claude-code/*|opencode/*) echo ""; return 0 ;;
+    claude-code|claude-code/*) echo ""; return 0 ;;
   esac
 
   # Only the registry path has knowable credential rules — see above.
@@ -46,16 +52,6 @@ gadfly_preflight_key() {
     return 0
   fi
 
-  # A provider is absent from this table for one of TWO different reasons — do
-  # not assume the first one and add an arm:
-  #   1. It needs no key, or carries it in its endpoint/DSN: local ollama,
-  #      llama-swap, foreman.
-  #   2. It needs a key but accepts more than one variable, so a single-name
-  #      check would skip a correctly-configured run. **google** is this case:
-  #      GOOGLE_API_KEY *or* GEMINI_API_KEY. Adding
-  #      `google) key_env="GOOGLE_API_KEY"` would silently skip every reviewer
-  #      configured with GEMINI_API_KEY. Pre-flighting google needs an
-  #      either-variable check, not this table's one-name shape.
   # ollama-cloud is checked on OLLAMA_API_KEY but hinted as OLLAMA_CLOUD_API_KEY:
   # run.sh copies the consumer-facing OLLAMA_CLOUD_API_KEY secret into the
   # OLLAMA_API_KEY the provider reads, BEFORE calling this. The hint names the
@@ -102,6 +98,8 @@ gadfly_preflight_key() {
 _gadfly_preflight_table() {
   printf '%s\n' \
     'ollama-cloud:OLLAMA_API_KEY:OLLAMA_CLOUD_API_KEY' \
+    'opencode:OLLAMA_API_KEY:OLLAMA_CLOUD_API_KEY' \
+    'open-code:OLLAMA_API_KEY:OLLAMA_CLOUD_API_KEY' \
     'qwen:QWEN_API_KEY:' \
     'kimi:KIMI_API_KEY:' \
     'openai:OPENAI_API_KEY:' \
diff --git a/scripts/preflight_test.sh b/scripts/preflight_test.sh
index 57b47df..c3093bc 100755
--- a/scripts/preflight_test.sh
+++ b/scripts/preflight_test.sh
@@ -90,7 +90,12 @@ echo "== engine specs carry their own auth and are never pre-flighted =="
 # CLAUDE_CODE_OAUTH_TOKEN, which needs no Ollama key.
 check "bare claude-code, no ollama key" "" "$(GADFLY_TEST_MODEL=claude-code probe ollama-cloud)"
 check "claude-code/opus, no ollama key" "" "$(GADFLY_TEST_MODEL=claude-code/opus probe ollama-cloud)"
-check "opencode/x, no ollama key"       "" "$(GADFLY_TEST_MODEL=opencode/x probe ollama-cloud)"
+# opencode is NOT exempt: it drives an ollama-cloud model and needs that key,
+# so skipping it would disable the pre-flight for the one engine it can help.
+check "opencode/x, no ollama key"       "OLLAMA_CLOUD_API_KEY" "$(GADFLY_TEST_MODEL=opencode/x probe opencode)"
+check "bare opencode, no ollama key"    "OLLAMA_CLOUD_API_KEY" "$(GADFLY_TEST_MODEL=opencode probe ollama-cloud)"
+check "open-code/x, no ollama key"      "OLLAMA_CLOUD_API_KEY" "$(GADFLY_TEST_MODEL=open-code/x probe open-code)"
+check "opencode/x, keyed"               "" "$(GADFLY_TEST_MODEL=opencode/x probe opencode OLLAMA_API_KEY=k)"
 # ...but a genuine ollama-cloud model still is.
 check "ollama-cloud model, no key"      "OLLAMA_CLOUD_API_KEY" "$(GADFLY_TEST_MODEL=glm-5.2:cloud probe ollama-cloud)"