fix: rewrite Vertex AI Model Garden provider to publisher for capability lookups

pkg/model/provider/vertexai/modelgarden.go

@@ -77,15 +77,63 @@ func IsModelGardenConfig(cfg *latest.ModelConfig) bool {
 //
 //   - publisher: anthropic → Anthropic-native `:streamRawPredict` endpoint.
 //   - other publishers → Vertex AI's OpenAI-compatible `/chat/completions`.
+//
+// The underlying client is constructed with a Provider field rewritten so
+// that downstream capability lookups against models.dev resolve correctly.
+// Without this rewrite, attachments and other capability-gated features are
+// silently dropped because `<provider>/<model>` IDs like
+// `google/claude-sonnet-4-20250514` do not exist in the models.dev database.
+// See modelsDevProvider for the exact mapping.
 func NewClient(ctx context.Context, cfg *latest.ModelConfig, env environment.Provider, opts ...options.Opt) (Client, error) {
 	project, location, err := resolveProjectLocation(ctx, cfg, env)
 	if err != nil {
 		return nil, err
 	}
+	rewritten := withModelsDevProvider(cfg)
 	if strings.EqualFold(publisher(cfg), "anthropic") {
-		return anthropic.NewVertexClient(ctx, cfg, env, project, location, opts...)
+		return anthropic.NewVertexClient(ctx, rewritten, env, project, location, opts...)
+	}
+	return newOpenAIClient(ctx, rewritten, env, project, location, opts...)
+}
+
+// withModelsDevProvider returns a deep copy of cfg with its Provider field
+// rewritten so that `Provider + "/" + Model` becomes a valid models.dev key.
+// The original cfg is never mutated so callers — and the wider runtime —
+// keep their "google" provider view.
+func withModelsDevProvider(cfg *latest.ModelConfig) *latest.ModelConfig {
+	out := cfg.Clone()
+	if p := modelsDevProvider(cfg); p != "" {
+		out.Provider = p
+	}
+	return out
+}
+
+// modelsDevProvider returns the models.dev provider key that hosts the model
+// described by cfg, or "" if the publisher is unset.
+//
+// On Vertex AI Model Garden the model-name format depends on the publisher:
+//
+//   - Anthropic Claude is referenced by a bare model name (no prefix), e.g.
+//     `claude-sonnet-4-20250514`. models.dev keys these under the top-level
+//     `anthropic` provider.
+//   - Other publishers are referenced via Vertex AI's OpenAI-compatible API
+//     with a `<publisher>/<model>` prefix, e.g.
+//     `meta/llama-4-maverick-17b-128e-instruct-maas`. models.dev keys these
+//     under `google-vertex` with the publisher prefix kept in the model name.
+//
+// Returning the publisher name unchanged for non-Anthropic models would
+// produce double-prefixed IDs like `meta/meta/llama-4-...` that do not exist
+// in models.dev.
+func modelsDevProvider(cfg *latest.ModelConfig) string {
+	p := strings.ToLower(strings.TrimSpace(publisher(cfg)))
+	switch p {
+	case "":
+		return ""
+	case "anthropic":
+		return "anthropic"
+	default:
+		return "google-vertex"
 	}
-	return newOpenAIClient(ctx, cfg, env, project, location, opts...)
 }
 
 // publisher returns the provider_opts.publisher string, or "" if unset.

pkg/model/provider/vertexai/modelgarden_test.go

@@ -4,6 +4,9 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
 	"github.com/docker/docker-agent/pkg/config/latest"
 	"github.com/docker/docker-agent/pkg/environment"
 )
@@ -72,6 +75,163 @@ func TestIsModelGardenConfig(t *testing.T) {
 	}
 }
 
+func TestWithModelsDevProvider(t *testing.T) {
+	tests := []struct {
+		name         string
+		cfg          *latest.ModelConfig
+		wantProvider string
+	}{
+		{
+			name: "anthropic publisher rewrites Provider to anthropic",
+			cfg: &latest.ModelConfig{
+				Provider:     "google",
+				Model:        "claude-sonnet-4-20250514",
+				ProviderOpts: map[string]any{"publisher": "anthropic"},
+			},
+			wantProvider: "anthropic",
+		},
+		{
+			name: "meta publisher rewrites Provider to google-vertex",
+			cfg: &latest.ModelConfig{
+				Provider:     "google",
+				Model:        "meta/llama-4-maverick-17b-128e-instruct-maas",
+				ProviderOpts: map[string]any{"publisher": "meta"},
+			},
+			wantProvider: "google-vertex",
+		},
+		{
+			name: "mistral publisher rewrites Provider to google-vertex",
+			cfg: &latest.ModelConfig{
+				Provider:     "google",
+				Model:        "mistral/mistral-large-2411",
+				ProviderOpts: map[string]any{"publisher": "mistral"},
+			},
+			wantProvider: "google-vertex",
+		},
+		{
+			name: "anthropic publisher is case-folded",
+			cfg: &latest.ModelConfig{
+				Provider:     "google",
+				Model:        "claude-sonnet-4-20250514",
+				ProviderOpts: map[string]any{"publisher": "Anthropic"},
+			},
+			wantProvider: "anthropic",
+		},
+		{
+			name: "publisher with surrounding whitespace is trimmed",
+			cfg: &latest.ModelConfig{
+				Provider:     "google",
+				Model:        "claude-sonnet-4-20250514",
+				ProviderOpts: map[string]any{"publisher": "  anthropic  "},
+			},
+			wantProvider: "anthropic",
+		},
+		{
+			name: "missing publisher leaves Provider untouched",
+			cfg: &latest.ModelConfig{
+				Provider: "google",
+				Model:    "gemini-2.5-flash",
+			},
+			wantProvider: "google",
+		},
+		{
+			name: "empty publisher leaves Provider untouched",
+			cfg: &latest.ModelConfig{
+				Provider:     "google",
+				Model:        "gemini-2.5-flash",
+				ProviderOpts: map[string]any{"publisher": ""},
+			},
+			wantProvider: "google",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			originalProvider := tt.cfg.Provider
+			originalPublisher, _ := tt.cfg.ProviderOpts["publisher"].(string)
+
+			got := withModelsDevProvider(tt.cfg)
+			require.NotNil(t, got)
+			require.NotSame(t, tt.cfg, got, "withModelsDevProvider must return a copy")
+			assert.Equal(t, tt.wantProvider, got.Provider)
+
+			// The original config must be unchanged so the wider runtime keeps its
+			// "google" provider view (used for routing, telemetry, ...).
+			assert.Equal(t, originalProvider, tt.cfg.Provider, "input cfg.Provider was mutated")
+			gotPublisher, _ := tt.cfg.ProviderOpts["publisher"].(string)
+			assert.Equal(t, originalPublisher, gotPublisher, "input cfg.ProviderOpts[publisher] was mutated")
+		})
+	}
+}
+
+// TestWithModelsDevProvider_CapabilityLookupIDs pins the bug fix for issue
+// #2740: the underlying provider client must compute its capability-lookup ID
+// in a form that exists in the models.dev database. Concretely:
+//
+//   - Anthropic Claude on Vertex AI: model name is bare (no prefix) and
+//     models.dev keys it under "anthropic/<model>".
+//   - Other publishers on Vertex AI: model name carries a "<publisher>/"
+//     prefix and models.dev keys it under "google-vertex/<publisher>/<model>".
+//
+// The test guards against the regression where rewriting Provider to the
+// publisher name (e.g. "meta") produced double-prefixed IDs like
+// "meta/meta/llama-..." that do not exist in models.dev.
+func TestWithModelsDevProvider_CapabilityLookupIDs(t *testing.T) {
+	tests := []struct {
+		name   string
+		cfg    *latest.ModelConfig
+		wantID string
+	}{
+		{
+			name: "anthropic claude",
+			cfg: &latest.ModelConfig{
+				Provider: "google",
+				Model:    "claude-sonnet-4-20250514",
+				ProviderOpts: map[string]any{
+					"project":   "my-project",
+					"location":  "us-east5",
+					"publisher": "anthropic",
+				},
+			},
+			wantID: "anthropic/claude-sonnet-4-20250514",
+		},
+		{
+			name: "meta llama keeps the meta/ prefix exactly once",
+			cfg: &latest.ModelConfig{
+				Provider: "google",
+				Model:    "meta/llama-4-maverick-17b-128e-instruct-maas",
+				ProviderOpts: map[string]any{
+					"project":   "my-project",
+					"location":  "us-central1",
+					"publisher": "meta",
+				},
+			},
+			wantID: "google-vertex/meta/llama-4-maverick-17b-128e-instruct-maas",
+		},
+		{
+			name: "mistral keeps its mistral/ prefix exactly once",
+			cfg: &latest.ModelConfig{
+				Provider: "google",
+				Model:    "mistral/mistral-large-2411",
+				ProviderOpts: map[string]any{
+					"project":   "my-project",
+					"location":  "us-central1",
+					"publisher": "mistral",
+				},
+			},
+			wantID: "google-vertex/mistral/mistral-large-2411",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			rewritten := withModelsDevProvider(tt.cfg)
+			gotID := rewritten.Provider + "/" + rewritten.DisplayOrModel()
+			assert.Equal(t, tt.wantID, gotID)
+		})
+	}
+}
+
 func TestPublisher(t *testing.T) {
 	tests := []struct {
 		name string