feat: multi-provider support — Ollama Cloud + OpenCode Go

- Account.Provider field (ollama-cloud | opencode-go), backward compatible
- Model-based routing: common models served by combined pool, unique models
  routed to their provider only
- /go/v1/* path forces OpenCode Go provider (prefix stripped upstream)
- Merged /v1/models endpoint returns union of both catalogs (44 models)
- Failover: 429/402 → cooldown + failover; 5xx → retry without cooldown
- CLI: accounts add --provider flag, list shows provider column
- Body buffering: request body buffered (8 MiB cap) for failover replay
- opencode integration: unified provider 'oc' with all merged models
- 64 tests pass (unit + integration)
- Verified: glm-5 → ollama, mimo-v2.5 → go, gpt-oss:20b → ollama

internal/proxy/model_router_test.go

@@ -0,0 +1,99 @@
+package proxy
+
+import (
+	"testing"
+
+	"github.com/Atte149/ollama-proxy/internal/config"
+)
+
+func TestProvidersForModel_Common(t *testing.T) {
+	for _, m := range []string{"glm-5", "glm-5.1", "glm-5.2", "kimi-k2.5", "kimi-k2.6",
+		"kimi-k2.7-code", "deepseek-v4-flash", "deepseek-v4-pro",
+		"minimax-m2.5", "minimax-m2.7", "minimax-m3"} {
+		ps := ProvidersForModel(m)
+		if len(ps) != 2 {
+			t.Errorf("ProvidersForModel(%q) = %v, want 2 providers", m, ps)
+			continue
+		}
+		if !IsCommonModel(m) {
+			t.Errorf("IsCommonModel(%q) = false, want true", m)
+		}
+	}
+}
+
+func TestProvidersForModel_UniqueOllama(t *testing.T) {
+	for _, m := range []string{"gpt-oss:20b", "gpt-oss:120b", "qwen3-coder:480b",
+		"gemma3:4b", "nemotron-3-ultra", "devstral-2:123b", "rnj-1:8b",
+		"mistral-large-3:675b", "minimax-m2.1", "glm-4.7", "gemini-3-flash-preview",
+		"qwen3.5:397b", "qwen3-coder-next", "ministral-3:3b",
+		"deepseek-v3.1:671b", "deepseek-v3.2"} {
+		ps := ProvidersForModel(m)
+		if len(ps) != 1 || ps[0] != config.ProviderOllamaCloud {
+			t.Errorf("ProvidersForModel(%q) = %v, want [ollama-cloud]", m, ps)
+		}
+		if IsCommonModel(m) {
+			t.Errorf("IsCommonModel(%q) = true, want false", m)
+		}
+	}
+}
+
+func TestProvidersForModel_UniqueGo(t *testing.T) {
+	for _, m := range []string{"mimo-v2.5", "mimo-v2.5-pro", "mimo-v2-omni", "mimo-v2-pro",
+		"qwen3.5-plus", "qwen3.6-plus", "qwen3.7-max", "qwen3.7-plus", "hy3-preview"} {
+		ps := ProvidersForModel(m)
+		if len(ps) != 1 || ps[0] != config.ProviderOpenCodeGo {
+			t.Errorf("ProvidersForModel(%q) = %v, want [opencode-go]", m, ps)
+		}
+		if IsCommonModel(m) {
+			t.Errorf("IsCommonModel(%q) = true, want false", m)
+		}
+	}
+}
+
+func TestProvidersForModel_UnknownDefaultsOllama(t *testing.T) {
+	ps := ProvidersForModel("bogus-model")
+	if len(ps) != 1 || ps[0] != config.ProviderOllamaCloud {
+		t.Errorf("ProvidersForModel(unknown) = %v, want [ollama-cloud]", ps)
+	}
+}
+
+func TestAllModels_DedupSorted(t *testing.T) {
+	all := AllModels()
+	if len(all) == 0 {
+		t.Fatal("AllModels returned empty list")
+	}
+	// Verify sorted.
+	for i := 1; i < len(all); i++ {
+		if all[i-1] >= all[i] {
+			t.Errorf("AllModels not sorted at %d: %q >= %q", i, all[i-1], all[i])
+		}
+	}
+	// Verify no duplicates.
+	seen := make(map[string]bool)
+	for _, m := range all {
+		if seen[m] {
+			t.Errorf("duplicate model in AllModels: %s", m)
+		}
+		seen[m] = true
+	}
+	// Common models must appear once, not twice.
+	common := "glm-5"
+	count := 0
+	for _, m := range all {
+		if m == common {
+			count++
+		}
+	}
+	if count != 1 {
+		t.Errorf("common model %s appeared %d times, want 1", common, count)
+	}
+}
+
+func TestProviderLabel(t *testing.T) {
+	if ProviderLabel(config.ProviderOllamaCloud) != "ollama" {
+		t.Error("ollama label wrong")
+	}
+	if ProviderLabel(config.ProviderOpenCodeGo) != "go" {
+		t.Error("go label wrong")
+	}
+}