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]>

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:' \

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)"