feat: multi-provider model support via majordomo (local Ollama, OpenAI-compatible, etc.)

Replace the hardcoded ollama.Cloud binding with majordomo's provider registry,
so Gadfly can target any backend majordomo supports without code changes.

- cmd/gadfly/model.go: resolveModel() — GADFLY_PROVIDER (default ollama-cloud)
  prefixes bare model ids; GADFLY_MODEL may be a full provider/model spec, alias,
  or failover chain (verbatim). GADFLY_BASE_URL constructs openai/ollama/anthropic/
  google directly at a custom endpoint (OpenAI-compatible + local/remote Ollama).
  GADFLY_API_KEY else the provider's standard env var. + buildSpec unit tests.
- run.sh: provider-aware key gate (local Ollama needs none); maps OLLAMA_CLOUD_API_KEY
  -> OLLAMA_API_KEY; provider/base-url/key inherited by the binary. Gadfly-branded comment.
- entrypoint.sh: GADFLY_MODELS alias for OLLAMA_REVIEW_MODELS; provider passthrough.
- examples + README: Models & providers section. Upfront: only the Ollama paths
  (local + OpenAI-compatible-against-Ollama) are tested; OpenAI/Anthropic/Google
  are wired via majordomo but UNTESTED (no spend).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

cmd/gadfly/main.go

@@ -20,8 +20,16 @@
 //
 // Inputs (env):
 //
-//	OLLAMA_API_KEY          Ollama Cloud bearer key (required).
-//	GADFLY_MODEL          model id, e.g. "qwen3-coder:480b-cloud" (required).
+//	GADFLY_MODEL          model id, or a full "provider/model" spec / majordomo
+//	                        alias / failover chain (required). A bare id is
+//	                        prefixed with GADFLY_PROVIDER.
+//	GADFLY_PROVIDER       provider for bare model ids (default "ollama-cloud";
+//	                        e.g. "ollama" for a local daemon, "openai", …).
+//	GADFLY_BASE_URL       override the backend endpoint (OpenAI/Ollama-compatible
+//	                        servers, remote Ollama, gateways). See model.go.
+//	GADFLY_API_KEY        provider key; optional — falls back to the provider's
+//	                        standard env (OLLAMA_API_KEY / OPENAI_API_KEY /
+//	                        ANTHROPIC_API_KEY / GOOGLE_API_KEY|GEMINI_API_KEY).
 //	GADFLY_REPO_DIR       path to the checked-out repo (required; the FS sandbox root).
 //	GADFLY_DIFF_FILE      path to a file holding the full unified diff (required).
 //	GADFLY_SYSTEM_FILE    path to the reviewer system prompt (required).
@@ -54,7 +62,6 @@ import (
 
 	"gitea.stevedudenhoeffer.com/steve/majordomo/agent"
 	llm "gitea.stevedudenhoeffer.com/steve/majordomo/llm"
-	"gitea.stevedudenhoeffer.com/steve/majordomo/provider/ollama"
 )
 
 const (
@@ -92,16 +99,11 @@ func main() {
 }
 
 func run() error {
-	apiKey := os.Getenv("OLLAMA_API_KEY")
-	if apiKey == "" {
-		return errors.New("OLLAMA_API_KEY is required")
-	}
-	model := os.Getenv("GADFLY_MODEL")
 	repoDir := os.Getenv("GADFLY_REPO_DIR")
 	diffFile := os.Getenv("GADFLY_DIFF_FILE")
 	systemFile := os.Getenv("GADFLY_SYSTEM_FILE")
-	if model == "" || repoDir == "" || diffFile == "" || systemFile == "" {
-		return errors.New("GADFLY_MODEL, GADFLY_REPO_DIR, GADFLY_DIFF_FILE and GADFLY_SYSTEM_FILE are all required")
+	if repoDir == "" || diffFile == "" || systemFile == "" {
+		return errors.New("GADFLY_REPO_DIR, GADFLY_DIFF_FILE and GADFLY_SYSTEM_FILE are all required")
 	}
 
 	diffBytes, err := os.ReadFile(diffFile)
@@ -123,9 +125,9 @@ func run() error {
 		return err
 	}
 
-	mdl, err := ollama.Cloud(ollama.WithToken(apiKey)).Model(model)
+	mdl, err := resolveModel()
 	if err != nil {
-		return fmt.Errorf("build model %q: %w", model, err)
+		return fmt.Errorf("resolve model: %w", err)
 	}
 
 	timeout := time.Duration(envInt("GADFLY_TIMEOUT_SECS", defaultTimeoutSecs)) * time.Second

cmd/gadfly/model.go

@@ -0,0 +1,100 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"gitea.stevedudenhoeffer.com/steve/majordomo"
+	llm "gitea.stevedudenhoeffer.com/steve/majordomo/llm"
+	"gitea.stevedudenhoeffer.com/steve/majordomo/provider/anthropic"
+	"gitea.stevedudenhoeffer.com/steve/majordomo/provider/google"
+	"gitea.stevedudenhoeffer.com/steve/majordomo/provider/ollama"
+	"gitea.stevedudenhoeffer.com/steve/majordomo/provider/openai"
+)
+
+// defaultProvider is the provider used when GADFLY_MODEL is a bare model id
+// (no "provider/" prefix). It keeps existing Ollama Cloud configs — where the
+// model list is just ids like "qwen3-coder:480b-cloud" — working unchanged.
+const defaultProvider = "ollama-cloud"
+
+// resolveModel builds the review model from the environment. Gadfly is powered
+// by majordomo, so it can target any provider majordomo supports — Ollama
+// (local or cloud), OpenAI, Anthropic, Google, or any OpenAI/Ollama-compatible
+// endpoint — without code changes.
+//
+// Env:
+//
+//	GADFLY_MODEL     model id, or a full "provider/model" spec, or a
+//	                 majordomo failover chain / alias (required).
+//	GADFLY_PROVIDER  provider prefix applied when GADFLY_MODEL has no "/"
+//	                 (default "ollama-cloud"). e.g. "ollama" for a local daemon.
+//	GADFLY_BASE_URL  override the backend endpoint (OpenAI/Ollama-compatible
+//	                 servers, a remote Ollama, an OpenRouter-style gateway…).
+//	                 When set, the provider is constructed directly at that URL.
+//	GADFLY_API_KEY   bearer/API key for the chosen provider. Optional; when
+//	                 unset the provider falls back to its standard env var
+//	                 (OLLAMA_API_KEY / OPENAI_API_KEY / ANTHROPIC_API_KEY /
+//	                 GOOGLE_API_KEY|GEMINI_API_KEY). Local Ollama needs none.
+//
+// With GADFLY_BASE_URL unset, resolution goes through majordomo's registry, so
+// LLM_* env DSNs and registered aliases/tiers work too.
+func resolveModel() (llm.Model, error) {
+	model := strings.TrimSpace(os.Getenv("GADFLY_MODEL"))
+	if model == "" {
+		return nil, fmt.Errorf("GADFLY_MODEL is required")
+	}
+	provider := strings.TrimSpace(os.Getenv("GADFLY_PROVIDER"))
+	if provider == "" {
+		provider = defaultProvider
+	}
+	baseURL := strings.TrimSpace(os.Getenv("GADFLY_BASE_URL"))
+	apiKey := os.Getenv("GADFLY_API_KEY")
+
+	// No endpoint override: let majordomo's registry resolve the spec. This
+	// path supports built-in providers (reading their standard key envs),
+	// LLM_* env DSNs, and aliases/failover chains.
+	if baseURL == "" {
+		return majordomo.Parse(buildSpec(provider, model))
+	}
+
+	// Endpoint override: construct the provider directly at the given URL.
+	switch provider {
+	case "openai", "openai-compatible":
+		opts := []openai.Option{openai.WithBaseURL(baseURL)}
+		if apiKey != "" {
+			opts = append(opts, openai.WithAPIKey(apiKey))
+		}
+		return openai.New(opts...).Model(model)
+	case "ollama", "ollama-cloud":
+		opts := []ollama.Option{ollama.WithBaseURL(baseURL)}
+		if apiKey != "" {
+			opts = append(opts, ollama.WithToken(apiKey))
+		}
+		return ollama.New(opts...).Model(model)
+	case "anthropic":
+		opts := []anthropic.Option{anthropic.WithBaseURL(baseURL)}
+		if apiKey != "" {
+			opts = append(opts, anthropic.WithAPIKey(apiKey))
+		}
+		return anthropic.New(opts...).Model(model)
+	case "google", "gemini":
+		opts := []google.Option{google.WithBaseURL(baseURL)}
+		if apiKey != "" {
+			opts = append(opts, google.WithAPIKey(apiKey))
+		}
+		return google.New(opts...).Model(model)
+	default:
+		return nil, fmt.Errorf("GADFLY_BASE_URL is set but GADFLY_PROVIDER %q has no endpoint-override support (use openai/ollama/anthropic/google, or unset GADFLY_BASE_URL to resolve via majordomo)", provider)
+	}
+}
+
+// buildSpec turns (provider, model) into a majordomo spec. A model id that
+// already carries a "provider/" prefix (or is a multi-element failover chain)
+// is passed through verbatim; a bare id is prefixed with the provider.
+func buildSpec(provider, model string) string {
+	if strings.Contains(model, "/") || strings.Contains(model, ",") {
+		return model
+	}
+	return provider + "/" + model
+}

cmd/gadfly/model_test.go

@@ -0,0 +1,25 @@
+package main
+
+import "testing"
+
+func TestBuildSpec(t *testing.T) {
+	tests := []struct {
+		name     string
+		provider string
+		model    string
+		want     string
+	}{
+		{"bare id gets provider prefix", "ollama-cloud", "qwen3-coder:480b-cloud", "ollama-cloud/qwen3-coder:480b-cloud"},
+		{"bare id local ollama", "ollama", "llama3.1", "ollama/llama3.1"},
+		{"already has provider passes through", "ollama-cloud", "openai/gpt-4o", "openai/gpt-4o"},
+		{"slashed model name passes through verbatim", "openai", "openai/meta-llama/Llama-3.1", "openai/meta-llama/Llama-3.1"},
+		{"failover chain passes through", "ollama-cloud", "anthropic/opus-4.8,ollama-cloud/qwen3-coder:480b-cloud", "anthropic/opus-4.8,ollama-cloud/qwen3-coder:480b-cloud"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := buildSpec(tt.provider, tt.model); got != tt.want {
+				t.Errorf("buildSpec(%q, %q) = %q, want %q", tt.provider, tt.model, got, tt.want)
+			}
+		})
+	}
+}