From 4fe15324c8e6d3efc0f57f121cc04c680fea7128 Mon Sep 17 00:00:00 2001
From: Atte149 <atte149@users.noreply.github.com>
Date: Wed, 24 Jun 2026 15:37:28 +0300
Subject: [PATCH] =?UTF-8?q?feat:=20multi-provider=20support=20=E2=80=94=20?=
 =?UTF-8?q?Ollama=20Cloud=20+=20OpenCode=20Go?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- 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
---
 AGENTS.md                           |  35 ++--
 internal/cli/accounts.go            |  56 ++++--
 internal/config/accounts.go         |  50 ++++-
 internal/config/accounts_test.go    |  54 ++++++
 internal/proxy/balancer.go          |  37 +++-
 internal/proxy/balancer_test.go     |  80 +++++++-
 internal/proxy/handler.go           | 289 ++++++++++++++++++++++------
 internal/proxy/handler_test.go      | 201 +++++++++++++++++++
 internal/proxy/model_router.go      | 116 +++++++++++
 internal/proxy/model_router_test.go |  99 ++++++++++
 internal/proxy/retry.go             |  81 +++++---
 11 files changed, 973 insertions(+), 125 deletions(-)
 create mode 100644 internal/proxy/model_router.go
 create mode 100644 internal/proxy/model_router_test.go

diff --git a/AGENTS.md b/AGENTS.md
index eb949ea..325fb8b 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -2,7 +2,7 @@
 
 ## Контекст
 
-`ollama-proxy` — Go-прокси для Ollama Cloud (`https://ollama.com`). Балансирует запросы по нескольким API-ключам с round-robin и failover на 429/5xx. Слушает `127.0.0.1:11435`, экспонирует нативный Ollama API (`/api/*`) и OpenAI-совместимый (`/v1/*`) passthrough. Деплой — systemd unit `ollama-proxy.service`. Используется opencode через кастомный провайдер `ocp`.
+`ollama-proxy` — Go-прокси для Ollama Cloud (`https://ollama.com`) и OpenCode Go (`https://opencode.ai/zen/go/v1`). Балансирует запросы по нескольким API-ключам с round-robin и failover на 429/402/5xx. Модели общие для обоих провайдеров идут одним пулом, уникальные — маршрутизируются к нужному провайдеру. Слушает `127.0.0.1:11435`, экспонирует OpenAI-совместимый (`/v1/*`) и нативный Ollama (`/api/*`) API. Деплой — systemd unit `ollama-proxy.service`. Используется opencode через кастомный провайдер `oc`.
 
 ## Стек
 
@@ -40,43 +40,50 @@ systemd/ollama-proxy.service   — systemd unit
 
 ## Типичные задачи
 
-- **Добавить аккаунт:** `ollama-proxy accounts add --name <alias>` (промпт) или `... add <key> --name <alias>`
+- **Добавить аккаунт:** `ollama-proxy accounts add --name <alias> --provider ollama-cloud|opencode-go` (промпт) или `... add <key> --name <alias> --provider <P>`
 - **Перезапустить после правки аккаунтов:** `sudo systemctl restart ollama-proxy` (прокси читает accounts.json при старте; runtime-обновления не поддерживаются)
-- **Посмотреть логи:** `journalctl -u ollama-proxy -f` — JSON-структурированные (account, account_id, path, status, latency_ms, stream)
+- **Посмотреть логи:** `journalctl -u ollama-proxy -f` — JSON-структурированные (account, account_id, provider, path, status, latency_ms, stream)
 - **Проверить, что прокси жив:** `curl http://127.0.0.1:11435/api/version` → должен вернуть JSON от ollama.com
-- **Проверить список моделей:** `curl http://127.0.0.1:11435/v1/models | jq '.data | length'` (~35 моделей)
+- **Проверить список моделей:** `curl http://127.0.0.1:11435/v1/models | jq '.data | length'` (~44 модели, merged из Ollama Cloud + OpenCode Go)
 - **Запустить opencode с пулом:** `openlama` (обёртка в `~/.local/bin/openlama`, выставляет NO_PROXY и запускает opencode)
-- **Обновить список моделей в opencode-конфиге:** `curl -sS http://127.0.0.1:11435/v1/models | jq -r '.data[].id'` → обновить `models` блок в `~/.config/opencode/opencode.json`
+- **Обновить список моделей в opencode-конфиге:** `curl -sS http://127.0.0.1:11435/v1/models | jq -r '.data[].id'` → обновить `models` блок в `~/.config/opencode/openlama.json`
 
 ## Интеграция с opencode
 
-**Два отдельных конфига:** `opencode` видит только marg/fireworks, `openlama` видит только ocp.
+**Два отдельных конфига:** `opencode` видит только marg/fireworks, `openlama` видит только `oc` (объединённый пул Ollama Cloud + OpenCode Go).
 
-- `~/.config/opencode/opencode.json` — глобальный конфиг с `marg` + `fireworks` (без `ocp`)
-- `~/.config/opencode/openlama.json` — отдельный конфиг с `ocp` + `"enabled_providers": ["ocp"]`. Содержит те же instructions/mcp/plugins/agent что глобальный, но только провайдер `ocp`.
+- `~/.config/opencode/opencode.json` — глобальный конфиг с `marg` + `fireworks` (без `oc`)
+- `~/.config/opencode/openlama.json` — отдельный конфиг с `oc` + `"enabled_providers": ["oc"]`. Содержит те же instructions/mcp/plugins/agent что глобальный, но только провайдер `oc`.
 - `~/.local/bin/openlama` — обёртка, выставляет `OPENCODE_CONFIG=~/.config/opencode/openlama.json` + `NO_PROXY=127.0.0.1,localhost,::1` + `exec opencode "$@"`
 
 openlama.json (ключевая часть):
 ```json
 {
-  "enabled_providers": ["ocp"],
+  "enabled_providers": ["oc"],
   "provider": {
-    "ocp": {
+    "oc": {
       "npm": "@ai-sdk/openai-compatible",
-      "name": "Ollama Cloud (pool)",
+      "name": "Ollama + OpenCode Go (pool)",
       "options": {
         "baseURL": "http://127.0.0.1:11435/v1",
         "apiKey": "proxy"
       },
       "models": {
-        "gpt-oss:20b": { "name": "gpt-oss:20b" },
-        "...": { "name": "..." }
+        "glm-5": { "name": "glm-5" },
+        "gpt-oss:20b": { "name": "gpt-oss:20b (ollama)" },
+        "mimo-v2.5": { "name": "mimo-v2.5 (go)" }
       }
     }
   }
 }
 ```
-`OPENCODE_CONFIG` мерджится с глобальным конфигом, но `enabled_providers: ["ocp"]` перекрывает глобальный — `marg`/`fireworks` скрыты.
+`OPENCODE_CONFIG` мерджится с глобальным конфигом, но `enabled_providers: ["oc"]` перекрывает глобальный — `marg`/`fireworks` скрыты.
+
+**Маршрутизация моделей:** прокси парсит `model` из тела запроса и выбирает eligible провайдеров:
+- Общие модели (glm-5, kimi-k2.6, deepseek-v4-flash и др.) → пул всех аккаунтов обоих провайдеров
+- Уникальные Ollama (gpt-oss:20b, qwen3-coder, gemma, nemotron) → только ollama-cloud аккаунты
+- Уникальные Go (mimo-v2.5, qwen3.5-plus, qwen3.7-max) → только opencode-go аккаунты
+- Также: `/go/v1/*` path force-рует opencode-go провайдер
 
 **Модель не сделана дефолтной** — выбирается через `/models` в TUI.
 
diff --git a/internal/cli/accounts.go b/internal/cli/accounts.go
index ca7da11..43cd6a8 100644
--- a/internal/cli/accounts.go
+++ b/internal/cli/accounts.go
@@ -37,16 +37,21 @@ func RunAccounts(args []string) int {
 
 func printAccountsUsage() {
 	fmt.Print(`Usage:
-  ollama-proxy accounts add [API_KEY] [--name <alias>]
+  ollama-proxy accounts add [API_KEY] [--name <alias>] [--provider ollama-cloud|opencode-go]
   ollama-proxy accounts list
   ollama-proxy accounts remove <id|name>
   ollama-proxy accounts set-base-url <url>
+
+Providers:
+  ollama-cloud   (default) Ollama Cloud at https://ollama.com — native + OpenAI API
+  opencode-go    OpenCode Go at https://opencode.ai/zen/go/v1 — OpenAI API only
 `)
 }
 
-// accountsAdd implements `accounts add [API_KEY] [--name <alias>]`.
+// accountsAdd implements `accounts add [API_KEY] [--name <alias>] [--provider P]`.
 func accountsAdd(args []string) int {
 	var apiKey, name string
+	provider := config.ProviderOllamaCloud
 	for i := 0; i < len(args); i++ {
 		switch args[i] {
 		case "--name":
@@ -56,8 +61,15 @@ func accountsAdd(args []string) int {
 			}
 			name = args[i+1]
 			i++
+		case "--provider":
+			if i+1 >= len(args) {
+				fmt.Fprintln(os.Stderr, "--provider requires an argument")
+				return 2
+			}
+			provider = config.ProviderType(args[i+1])
+			i++
 		case "-h", "--help":
-			fmt.Println("usage: accounts add [API_KEY] [--name <alias>]")
+			fmt.Println("usage: accounts add [API_KEY] [--name <alias>] [--provider ollama-cloud|opencode-go]")
 			return 0
 		default:
 			if apiKey == "" {
@@ -69,6 +81,11 @@ func accountsAdd(args []string) int {
 		}
 	}
 
+	if !config.ValidProvider(provider) {
+		fmt.Fprintf(os.Stderr, "unknown provider %q (use ollama-cloud or opencode-go)\n", provider)
+		return 2
+	}
+
 	if name == "" {
 		name = promptString("Account name (alias)", "acct"+config.NewID()[:4])
 	}
@@ -78,7 +95,14 @@ func accountsAdd(args []string) int {
 	}
 
 	if apiKey == "" {
-		fmt.Print("Enter Ollama Cloud API key (input hidden): ")
+		label := "API key"
+		switch provider {
+		case config.ProviderOpenCodeGo:
+			label = "OpenCode Go API key"
+		case config.ProviderOllamaCloud:
+			label = "Ollama Cloud API key"
+		}
+		fmt.Printf("Enter %s (input hidden): ", label)
 		b, err := term.ReadPassword(int(os.Stdin.Fd()))
 		fmt.Println()
 		if err != nil {
@@ -106,17 +130,19 @@ func accountsAdd(args []string) int {
 		return 2
 	}
 	acct := config.Account{
-		ID:      config.NewID(),
-		Name:    name,
-		APIKey:  apiKey,
-		Created: nowFn(),
+		ID:       config.NewID(),
+		Name:     name,
+		Provider: provider,
+		APIKey:   apiKey,
+		Created:  nowFn(),
 	}
 	af.Accounts = append(af.Accounts, acct)
 	if err := af.Save(); err != nil {
 		fmt.Fprintln(os.Stderr, "save accounts:", err)
 		return 1
 	}
-	fmt.Printf("added account %s (name=%s key=%s)\n", acct.ID[:8], acct.Name, maskKey(acct.APIKey))
+	fmt.Printf("added account %s (name=%s provider=%s key=%s)\n",
+		acct.ID[:8], acct.Name, acct.Provider, maskKey(acct.APIKey))
 	return 0
 }
 
@@ -133,15 +159,21 @@ func accountsList(args []string) int {
 	}
 	w := bufio.NewWriter(os.Stdout)
 	defer w.Flush()
-	fmt.Fprintf(w, "%-10s %-16s %-18s %-22s\n", "ID", "NAME", "KEY", "CREATED")
-	fmt.Fprintf(w, "%-10s %-16s %-18s %-22s\n", strings.Repeat("-", 8), strings.Repeat("-", 14), strings.Repeat("-", 16), strings.Repeat("-", 20))
+	fmt.Fprintf(w, "%-10s %-14s %-16s %-18s %-22s\n", "ID", "PROVIDER", "NAME", "KEY", "CREATED")
+	fmt.Fprintf(w, "%-10s %-14s %-16s %-18s %-22s\n",
+		strings.Repeat("-", 8), strings.Repeat("-", 12), strings.Repeat("-", 14),
+		strings.Repeat("-", 16), strings.Repeat("-", 20))
 	for _, a := range af.Accounts {
 		id := a.ID
 		if len(id) > 8 {
 			id = id[:8]
 		}
+		prov := string(a.Provider)
+		if prov == "" {
+			prov = string(config.ProviderOllamaCloud)
+		}
 		created := a.Created.Format("2006-01-02 15:04 MST")
-		fmt.Fprintf(w, "%-10s %-16s %-18s %-22s\n", id, a.Name, maskKey(a.APIKey), created)
+		fmt.Fprintf(w, "%-10s %-14s %-16s %-18s %-22s\n", id, prov, a.Name, maskKey(a.APIKey), created)
 	}
 	if af.BaseURL != "" {
 		fmt.Fprintf(w, "\nDefault upstream: %s\n", af.BaseURL)
diff --git a/internal/config/accounts.go b/internal/config/accounts.go
index d214d82..b6bfbf9 100644
--- a/internal/config/accounts.go
+++ b/internal/config/accounts.go
@@ -14,13 +14,44 @@ import (
 	"time"
 )
 
-// Account is a single Ollama Cloud API key with an optional alias.
+// ProviderType identifies which upstream service an account belongs to.
+type ProviderType string
+
+const (
+	// ProviderOllamaCloud is the Ollama Cloud API at https://ollama.com.
+	ProviderOllamaCloud ProviderType = "ollama-cloud"
+	// ProviderOpenCodeGo is the OpenCode Go API at https://opencode.ai/zen/go/v1.
+	ProviderOpenCodeGo ProviderType = "opencode-go"
+)
+
+// DefaultProviderBaseURL returns the canonical upstream root for a provider.
+func DefaultProviderBaseURL(p ProviderType) string {
+	switch p {
+	case ProviderOpenCodeGo:
+		return "https://opencode.ai/zen/go"
+	default:
+		return "https://ollama.com"
+	}
+}
+
+// ValidProvider reports whether p is a recognised provider type.
+func ValidProvider(p ProviderType) bool {
+	switch p {
+	case ProviderOllamaCloud, ProviderOpenCodeGo:
+		return true
+	default:
+		return false
+	}
+}
+
+// Account is a single upstream API key with an optional alias.
 type Account struct {
-	ID      string    `json:"id"`
-	Name    string    `json:"name"`
-	APIKey  string    `json:"api_key"`
-	BaseURL string    `json:"base_url,omitempty"` // overrides ServerConfig.BaseURL; empty = use default
-	Created time.Time `json:"created"`
+	ID       string       `json:"id"`
+	Name     string       `json:"name"`
+	Provider ProviderType `json:"provider,omitempty"` // empty = ollama-cloud (backward compat)
+	APIKey   string       `json:"api_key"`
+	BaseURL  string       `json:"base_url,omitempty"` // overrides the provider default; empty = use default
+	Created  time.Time    `json:"created"`
 }
 
 // AccountsFile is the on-disk JSON structure.
@@ -73,6 +104,13 @@ func LoadAccounts() (*AccountsFile, error) {
 	if err := json.Unmarshal(data, &af); err != nil {
 		return nil, fmt.Errorf("parse accounts: %w", err)
 	}
+	// Backward compat: accounts without an explicit provider default to
+	// ollama-cloud (the original behaviour before multi-provider support).
+	for i := range af.Accounts {
+		if af.Accounts[i].Provider == "" {
+			af.Accounts[i].Provider = ProviderOllamaCloud
+		}
+	}
 	return &af, nil
 }
 
diff --git a/internal/config/accounts_test.go b/internal/config/accounts_test.go
index 342902e..abbf231 100644
--- a/internal/config/accounts_test.go
+++ b/internal/config/accounts_test.go
@@ -77,6 +77,60 @@ func TestValidateName(t *testing.T) {
 	}
 }
 
+func TestProviderType_Constants(t *testing.T) {
+	if ProviderOllamaCloud != "ollama-cloud" {
+		t.Errorf("ProviderOllamaCloud = %q", ProviderOllamaCloud)
+	}
+	if ProviderOpenCodeGo != "opencode-go" {
+		t.Errorf("ProviderOpenCodeGo = %q", ProviderOpenCodeGo)
+	}
+	if !ValidProvider(ProviderOllamaCloud) || !ValidProvider(ProviderOpenCodeGo) {
+		t.Error("ValidProvider returned false for known providers")
+	}
+	if ValidProvider(ProviderType("bogus")) {
+		t.Error("ValidProvider returned true for bogus provider")
+	}
+}
+
+func TestDefaultProviderBaseURL(t *testing.T) {
+	if DefaultProviderBaseURL(ProviderOllamaCloud) != "https://ollama.com" {
+		t.Errorf("ollama base url = %q", DefaultProviderBaseURL(ProviderOllamaCloud))
+	}
+	if DefaultProviderBaseURL(ProviderOpenCodeGo) != "https://opencode.ai/zen/go" {
+		t.Errorf("go base url = %q", DefaultProviderBaseURL(ProviderOpenCodeGo))
+	}
+}
+
+// TestLoadAccounts_BackwardCompatProvider verifies that accounts.json entries
+// without a "provider" field are normalised to ollama-cloud on load.
+func TestLoadAccounts_BackwardCompatProvider(t *testing.T) {
+	p := withTempAccountsPath(t)
+	// Write an old-style file with no provider field.
+	old := `{
+	  "base_url": "https://ollama.com",
+	  "accounts": [
+	    {"id":"abc","name":"legacy","api_key":"sk-xyz","created":"2026-06-19T10:00:00Z"},
+	    {"id":"def","name":"go1","provider":"opencode-go","api_key":"sk-go","created":"2026-06-19T10:00:00Z"}
+	  ]
+	}`
+	if err := os.WriteFile(p, []byte(old), 0o600); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+	af, err := LoadAccounts()
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+	if len(af.Accounts) != 2 {
+		t.Fatalf("len = %d", len(af.Accounts))
+	}
+	if af.Accounts[0].Name != "legacy" || af.Accounts[0].Provider != ProviderOllamaCloud {
+		t.Errorf("legacy account provider = %q, want ollama-cloud", af.Accounts[0].Provider)
+	}
+	if af.Accounts[1].Provider != ProviderOpenCodeGo {
+		t.Errorf("go account provider = %q, want opencode-go", af.Accounts[1].Provider)
+	}
+}
+
 func TestLoadAccounts_MissingFile(t *testing.T) {
 	withTempAccountsPath(t)
 	af, err := LoadAccounts()
diff --git a/internal/proxy/balancer.go b/internal/proxy/balancer.go
index 4f8b9c2..40d3876 100644
--- a/internal/proxy/balancer.go
+++ b/internal/proxy/balancer.go
@@ -27,9 +27,14 @@ type Balancer struct {
 // is applied uniformly to all accounts. At least one account is required;
 // otherwise Next returns ErrNoAccounts on every call.
 func NewBalancer(accounts []config.Account, cooldown time.Duration) *Balancer {
-	// copy to avoid external mutation
+	// copy to avoid external mutation; normalise empty provider to ollama-cloud.
 	accts := make([]config.Account, len(accounts))
-	copy(accts, accounts)
+	for i, a := range accounts {
+		if a.Provider == "" {
+			a.Provider = config.ProviderOllamaCloud
+		}
+		accts[i] = a
+	}
 	return &Balancer{
 		accounts:    accts,
 		cooldown:    make(map[string]time.Time),
@@ -70,21 +75,41 @@ func (e ErrAllCooldown) Error() string {
 // rotates starting from the round-robin counter so consecutive calls land on
 // different accounts when possible. Returns ErrNoAccounts or ErrAllCooldown
 // when nothing is available.
+//
+// Next considers all accounts regardless of provider. Use NextFor to restrict
+// to a set of eligible providers (e.g. for model-based routing).
 func (b *Balancer) Next() (config.Account, error) {
+	return b.NextFor(nil)
+}
+
+// NextFor picks the next available account whose provider is in the eligible
+// list. When eligible is nil or empty, all providers are eligible (matches
+// the original Next behaviour). Accounts in cooldown are skipped.
+func (b *Balancer) NextFor(eligible []config.ProviderType) (config.Account, error) {
 	if len(b.accounts) == 0 {
 		return config.Account{}, ErrNoAccounts{}
 	}
+	allowed := make(map[config.ProviderType]bool, len(eligible))
+	for _, p := range eligible {
+		allowed[p] = true
+	}
+	allAllowed := len(eligible) == 0
+
 	now := time.Now()
 	var earliest time.Time
 	for i := 0; i < len(b.accounts); i++ {
 		idx := int(b.rr.Add(1)) % len(b.accounts)
+		acct := b.accounts[idx]
 		// idx is computed from the *new* counter value; we Add-then-mod so each
 		// call advances even if this loop iteration rejects the candidate.
-		if !b.isCooldown(b.accounts[idx].ID, now) {
-			return b.accounts[idx], nil
+		if !allAllowed && !allowed[acct.Provider] {
+			continue
 		}
-		if earliest.IsZero() || b.cooldownUntil(b.accounts[idx].ID).Before(earliest) {
-			earliest = b.cooldownUntil(b.accounts[idx].ID)
+		if !b.isCooldown(acct.ID, now) {
+			return acct, nil
+		}
+		if earliest.IsZero() || b.cooldownUntil(acct.ID).Before(earliest) {
+			earliest = b.cooldownUntil(acct.ID)
 		}
 	}
 	return config.Account{}, ErrAllCooldown{Until: earliest}
diff --git a/internal/proxy/balancer_test.go b/internal/proxy/balancer_test.go
index 57af6f7..a1a349b 100644
--- a/internal/proxy/balancer_test.go
+++ b/internal/proxy/balancer_test.go
@@ -11,11 +11,25 @@ import (
 func mkAccts(n int) []config.Account {
 	out := make([]config.Account, n)
 	for i := range out {
-		out[i] = config.Account{ID: "id" + string(rune('a'+i)), Name: "a" + string(rune('a'+i)), APIKey: "k" + string(rune('a'+i))}
+		out[i] = config.Account{
+			ID:       "id" + string(rune('a'+i)),
+			Name:     "a" + string(rune('a'+i)),
+			APIKey:   "k" + string(rune('a'+i)),
+			Provider: config.ProviderOllamaCloud,
+		}
 	}
 	return out
 }
 
+func mkMixedAccts() []config.Account {
+	return []config.Account{
+		{ID: "idO1", Name: "o1", APIKey: "k1", Provider: config.ProviderOllamaCloud},
+		{ID: "idO2", Name: "o2", APIKey: "k2", Provider: config.ProviderOllamaCloud},
+		{ID: "idG1", Name: "g1", APIKey: "k3", Provider: config.ProviderOpenCodeGo},
+		{ID: "idG2", Name: "g2", APIKey: "k4", Provider: config.ProviderOpenCodeGo},
+	}
+}
+
 func TestBalancer_Next_RoundRobin(t *testing.T) {
 	b := NewBalancer(mkAccts(3), 60*time.Second)
 	seen := make(map[string]int)
@@ -158,3 +172,67 @@ func TestBalancer_CooldownExpires(t *testing.T) {
 		t.Errorf("Next after cooldown expiry: %v", err)
 	}
 }
+
+func TestBalancer_NextFor_FiltersByProvider(t *testing.T) {
+	accts := mkMixedAccts()
+	b := NewBalancer(accts, 60*time.Second)
+	// Request only OpenCode Go accounts: every result must be a Go account.
+	seen := map[string]int{}
+	for i := 0; i < 8; i++ {
+		a, err := b.NextFor([]config.ProviderType{config.ProviderOpenCodeGo})
+		if err != nil {
+			t.Fatalf("NextFor %d: %v", i, err)
+		}
+		if a.Provider != config.ProviderOpenCodeGo {
+			t.Errorf("NextFor returned provider %q, want opencode-go", a.Provider)
+		}
+		seen[a.ID]++
+	}
+	if len(seen) != 2 {
+		t.Errorf("expected 2 distinct go accounts, got %d", len(seen))
+	}
+}
+
+func TestBalancer_NextFor_MixedPool(t *testing.T) {
+	accts := mkMixedAccts()
+	b := NewBalancer(accts, 60*time.Second)
+	// Eligible = both providers: all 4 accounts should be reachable.
+	seen := map[string]bool{}
+	for i := 0; i < 16; i++ {
+		a, err := b.NextFor([]config.ProviderType{
+			config.ProviderOllamaCloud, config.ProviderOpenCodeGo,
+		})
+		if err != nil {
+			t.Fatalf("NextFor %d: %v", i, err)
+		}
+		seen[a.ID] = true
+	}
+	if len(seen) != 4 {
+		t.Errorf("expected 4 distinct accounts in mixed pool, got %d", len(seen))
+	}
+}
+
+func TestBalancer_NextFor_NilEligibleReturnsAll(t *testing.T) {
+	accts := mkMixedAccts()
+	b := NewBalancer(accts, 60*time.Second)
+	seen := map[config.ProviderType]bool{}
+	for i := 0; i < 16; i++ {
+		a, err := b.NextFor(nil)
+		if err != nil {
+			t.Fatalf("NextFor nil %d: %v", i, err)
+		}
+		seen[a.Provider] = true
+	}
+	if !seen[config.ProviderOllamaCloud] || !seen[config.ProviderOpenCodeGo] {
+		t.Errorf("nil eligible should include both providers, got %v", seen)
+	}
+}
+
+func TestBalancer_NextFor_NoEligibleAccounts(t *testing.T) {
+	// Only Ollama accounts configured, but requesting Go.
+	b := NewBalancer(mkAccts(2), 60*time.Second)
+	_, err := b.NextFor([]config.ProviderType{config.ProviderOpenCodeGo})
+	if _, ok := err.(ErrAllCooldown); !ok && err == nil {
+		t.Errorf("NextFor with no eligible accounts: %v, want error or ErrAllCooldown", err)
+	}
+}
diff --git a/internal/proxy/handler.go b/internal/proxy/handler.go
index 12f0941..0eed729 100644
--- a/internal/proxy/handler.go
+++ b/internal/proxy/handler.go
@@ -1,6 +1,7 @@
 package proxy
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -8,41 +9,58 @@ import (
 	"net/http"
 	"strings"
 	"time"
+
+	"github.com/Atte149/ollama-proxy/internal/config"
 )
 
-// Handler is the http.Handler that proxies incoming requests to Ollama Cloud
-// through the balancer, applying per-account Authorization and failover logic.
+// Handler is the http.Handler that proxies incoming requests to upstream
+// providers (Ollama Cloud and OpenCode Go) through the balancer, applying
+// per-account Authorization and failover logic.
 type Handler struct {
 	Balancer *Balancer
-	BaseURL  string // upstream root, e.g. "https://ollama.com"
-	Client   *http.Client
 	Log      *slog.Logger
+	Client   *http.Client
 	Retries  int // max attempts per request (= number of accounts to try)
+	// DefaultBaseURL, when non-empty, overrides the provider-default upstream
+	// root for accounts that have no explicit BaseURL. This is primarily used
+	// by the --base-url flag for local testing; in production accounts rely on
+	// the provider default.
+	DefaultBaseURL string
 }
 
-// NewHandler builds a Handler with sensible HTTP client defaults (no timeout
-// on the overall request — streaming responses can be long; per-read timeout
-// is governed by the caller's context).
+// NewHandler builds a Handler with sensible HTTP client defaults.
 func NewHandler(b *Balancer, baseURL string, retries int, log *slog.Logger) *Handler {
 	return &Handler{
 		Balancer: b,
-		BaseURL:  strings.TrimRight(baseURL, "/"),
+		Log:      log,
 		Client: &http.Client{
-			// No overall timeout: streaming chat may take minutes. The caller's
-			// request context (cancelled when the client disconnects) still
-			// propagates through to upstream via NewWithContext.
 			Timeout: 0,
 			CheckRedirect: func(req *http.Request, via []*http.Request) error {
-				return http.ErrUseLastResponse // don't follow redirects automatically
+				return http.ErrUseLastResponse
 			},
 		},
-		Log:     log,
-		Retries: retries,
+		Retries:        retries,
+		DefaultBaseURL: baseURL,
 	}
 }
 
-// allowedPaths is the allowlist of upstream paths the proxy will forward.
-// Anything else returns 404 — we never proxy arbitrary paths.
+// upstreamBaseURL resolves the canonical upstream root for an account:
+//  1. The account's own BaseURL override (highest priority)
+//  2. The handler's DefaultBaseURL — but ONLY for ollama-cloud accounts,
+//     since --base-url is an Ollama-specific flag used for local testing
+//  3. The provider default
+func (h *Handler) upstreamBaseURL(acct config.Account) string {
+	if acct.BaseURL != "" {
+		return strings.TrimRight(acct.BaseURL, "/")
+	}
+	if h.DefaultBaseURL != "" && acct.Provider == config.ProviderOllamaCloud {
+		return strings.TrimRight(h.DefaultBaseURL, "/")
+	}
+	return strings.TrimRight(config.DefaultProviderBaseURL(acct.Provider), "/")
+}
+
+// allowedPaths is the allowlist of paths the proxy will forward. The same set
+// is used for both providers; the /go/ prefix routes to OpenCode Go.
 var allowedPaths = map[string]bool{
 	"/api/chat":            true,
 	"/api/generate":        true,
@@ -58,13 +76,11 @@ var allowedPaths = map[string]bool{
 	"/v1/files":            true,
 }
 
-// isAllowed reports whether a path (possibly with a trailing slash or query)
-// matches one of the allowed upstream endpoints.
+// isAllowed reports whether a path matches an allowed upstream endpoint.
 func isAllowed(path string) bool {
 	if allowedPaths[path] {
 		return true
 	}
-	// allow sub-paths like /v1/files/<id> under an allowed prefix.
 	for prefix := range allowedPaths {
 		if strings.HasPrefix(path, prefix+"/") {
 			return true
@@ -73,9 +89,72 @@ func isAllowed(path string) bool {
 	return false
 }
 
-// ServeHTTP proxies a single client request to Ollama Cloud with failover.
+// routePath normalises the incoming path and returns (upstreamPath, forcedProvider).
+// Paths under /go/ force the OpenCode Go provider and have the /go prefix
+// stripped before forwarding. Otherwise the provider is chosen by the request
+// body model (or defaults to ollama-cloud when no model is present).
+func routePath(path string) (upstreamPath string, forced config.ProviderType, isGo bool) {
+	if strings.HasPrefix(path, "/go/") || path == "/go" {
+		return "/" + strings.TrimPrefix(path, "/go/"), config.ProviderOpenCodeGo, true
+	}
+	return path, "", false
+}
+
+// modelFromBody extracts the "model" field from a buffered request body.
+// Returns "" when the body is nil, empty, or does not contain a parseable
+// JSON object with a model field. Does not consume the buffer (resets position).
+func modelFromBody(body *bufferedBody) string {
+	if body == nil || len(body.data) == 0 {
+		return ""
+	}
+	var probe struct {
+		Model string `json:"model"`
+	}
+	if err := json.Unmarshal(body.data, &probe); err != nil {
+		return ""
+	}
+	return probe.Model
+}
+
+// bufferedBody wraps a []byte so it can be replayed across failover attempts.
+type bufferedBody struct {
+	data []byte
+	pos  int
+}
+
+func (b *bufferedBody) Read(p []byte) (int, error) {
+	if b.pos >= len(b.data) {
+		return 0, io.EOF
+	}
+	n := copy(p, b.data[b.pos:])
+	b.pos += n
+	return n, nil
+}
+func (b *bufferedBody) Close() error { return nil }
+func (b *bufferedBody) reset()       { b.pos = 0 }
+
+// bufferRequestBody reads the request body (up to a cap) into a buffer so it
+// can be replayed across failover attempts. Bodies larger than the cap are
+// not buffered and the request is not retried. Returns nil for streaming-safe
+// GET/DELETE requests.
+func bufferRequestBody(r *http.Request) *bufferedBody {
+	if r.Body == nil || r.Method == http.MethodGet || r.Method == http.MethodDelete ||
+		r.Method == http.MethodHead {
+		return nil
+	}
+	const cap = 8 << 20 // 8 MiB
+	data, err := io.ReadAll(io.LimitReader(r.Body, cap+1))
+	if err != nil || len(data) > cap {
+		return nil // too large or unreadable; disable retries by returning nil
+	}
+	return &bufferedBody{data: data}
+}
+
+// ServeHTTP proxies a single client request to the upstream with failover.
 func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	if !isAllowed(r.URL.Path) {
+	upstreamPath, forced, isGo := routePath(r.URL.Path)
+	_ = isGo
+	if !isAllowed(upstreamPath) {
 		http.NotFound(w, r)
 		return
 	}
@@ -84,32 +163,101 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Buffer the request body up front so we can both extract the model field
+	// and replay the body across failover attempts. This must happen BEFORE
+	// requestModel reads from r.Body.
+	bodyBuf := bufferRequestBody(r)
+
+	// Determine eligible providers for this request.
+	var eligible []config.ProviderType
+	switch {
+	case forced != "":
+		// /go/* path forces the OpenCode Go provider.
+		eligible = []config.ProviderType{forced}
+	case upstreamPath == "/v1/models" || upstreamPath == "/api/tags":
+		// Listing endpoints: handled specially below (merged response).
+		h.handleModelsEndpoint(w, r, upstreamPath)
+		return
+	case upstreamPath == "/api/version":
+		// Version is Ollama-specific; route to Ollama Cloud.
+		eligible = []config.ProviderType{config.ProviderOllamaCloud}
+	default:
+		// Chat/generate/etc.: route by the model in the body.
+		model := modelFromBody(bodyBuf)
+		if model == "" {
+			eligible = nil // any provider
+		} else {
+			eligible = ProvidersForModel(model)
+		}
+	}
+
 	maxAttempts := h.Retries
 	if maxAttempts < 1 {
 		maxAttempts = 1
 	}
-	if maxAttempts > h.Balancer.Len() {
-		maxAttempts = h.Balancer.Len()
+	if n := h.Balancer.Len(); maxAttempts > n {
+		maxAttempts = n
 	}
 
-	h.proxyWithFailover(w, r, maxAttempts)
+	h.proxyWithFailover(w, r, upstreamPath, eligible, bodyBuf, maxAttempts)
 }
 
-// proxyWithFailover tries up to maxAttempts accounts. The first attempt that
-// begins streaming (returns headers + a 2xx) commits: we copy the rest of the
-// response to the client verbatim and stop retrying. Pre-stream 429/5xx move
-// on to the next account.
-func (h *Handler) proxyWithFailover(w http.ResponseWriter, r *http.Request, maxAttempts int) {
+// handleModelsEndpoint returns a merged list of all known models for
+// /v1/models (OpenAI format) or /api/tags (Ollama format).
+func (h *Handler) handleModelsEndpoint(w http.ResponseWriter, r *http.Request, path string) {
+	now := time.Now().Unix()
+	models := AllModels()
+	if path == "/v1/models" {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(200)
+		var sb strings.Builder
+		sb.WriteString(`{"object":"list","data":[`)
+		for i, m := range models {
+			if i > 0 {
+				sb.WriteByte(',')
+			}
+			// The id is the raw model ID (used in API requests). The name
+			// includes a provider label for unique models so users can tell
+			// them apart in the opencode model picker.
+			name := m
+			if !IsCommonModel(m) {
+				name = m + " (" + ProviderLabel(ProvidersForModel(m)[0]) + ")"
+			}
+			fmt.Fprintf(&sb, `{"id":%q,"object":"model","created":%d,"owned_by":"ollama-proxy"}`,
+				m, now)
+			_ = name // name is conveyed via opencode config, not this endpoint
+		}
+		sb.WriteString(`]}`)
+		_, _ = w.Write([]byte(sb.String()))
+		return
+	}
+	// /api/tags — Ollama format
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(200)
+	var sb strings.Builder
+	sb.WriteString(`{"models":[`)
+	for i, m := range models {
+		if i > 0 {
+			sb.WriteByte(',')
+		}
+		fmt.Fprintf(&sb, `{"name":%q,"model":%q,"modified_at":"","size":0,"digest":""}`, m, m)
+	}
+	sb.WriteString(`]}`)
+	_, _ = w.Write([]byte(sb.String()))
+}
+
+// proxyWithFailover tries up to maxAttempts accounts eligible for the request.
+func (h *Handler) proxyWithFailover(w http.ResponseWriter, r *http.Request,
+	upstreamPath string, eligible []config.ProviderType, body *bufferedBody,
+	maxAttempts int) {
 	ctx := r.Context()
 	var lastErr error
 
 	for attempt := 0; attempt < maxAttempts; attempt++ {
-		acct, err := h.Balancer.Next()
+		acct, err := h.Balancer.NextFor(eligible)
 		if err != nil {
-			// No accounts available.
 			switch err.(type) {
 			case ErrAllCooldown:
-				// All accounts rate-limited upstream → propagate 429 to client.
 				msg := err.Error()
 				if lastErr != nil {
 					msg = msg + "; last upstream error: " + lastErr.Error()
@@ -125,43 +273,58 @@ func (h *Handler) proxyWithFailover(w http.ResponseWriter, r *http.Request, maxA
 			}
 		}
 
-		// Build the upstream request, substituting the account's key.
-		upstreamURL := h.BaseURL + r.URL.RequestURI()
-		// Per-account BaseURL override wins when set.
-		if acct.BaseURL != "" {
-			upstreamURL = strings.TrimRight(acct.BaseURL, "/") + r.URL.RequestURI()
+		// Build the upstream request.
+		base := h.upstreamBaseURL(acct)
+		// Build the upstream URI from the routed path + original query string.
+		uri := upstreamPath
+		if r.URL.RawQuery != "" {
+			uri += "?" + r.URL.RawQuery
 		}
-		req, err := http.NewRequestWithContext(ctx, r.Method, upstreamURL, r.Body)
+		upstreamURL := base + uri
+
+		var bodyReader io.Reader
+		if body != nil {
+			body.reset()
+			bodyReader = body
+		} else if r.Body != nil {
+			bodyReader = r.Body
+		}
+		req, err := http.NewRequestWithContext(ctx, r.Method, upstreamURL, bodyReader)
 		if err != nil {
 			lastErr = fmt.Errorf("build request: %w", err)
 			continue
 		}
-		// Copy headers, replacing Authorization with the account key.
 		copyHeaders(req.Header, r.Header)
 		req.Header.Set("Authorization", "Bearer "+acct.APIKey)
-		req.Host = "" // let the URL determine Host
+		// OpenCode Go uses OpenAI-compatible JSON; ensure content-type is set.
+		if req.Header.Get("Content-Type") == "" {
+			req.Header.Set("Content-Type", "application/json")
+		}
+		// Let the URL determine the Host header (do not clear it; clearing can
+		// cause some CDNs to reject the request with 401/403).
 
 		start := time.Now()
 		resp, err := h.Client.Do(req)
 		latency := time.Since(start)
 		if err != nil {
-			// Network/timeout error: log and try next account.
 			h.Log.Warn("upstream request failed",
 				"account", acct.Name, "account_id", acct.ID,
+				"provider", string(acct.Provider),
 				"path", r.URL.Path, "latency_ms", latency.Milliseconds(), "err", err)
 			lastErr = err
 			continue
 		}
 
-		// Pre-stream decision: 429 or 5xx → cooldown + failover.
-		if resp.StatusCode == http.StatusTooManyRequests || resp.StatusCode >= 500 {
-			bodyPreview := readPreview(resp.Body, 256)
+		// Pre-stream decision: retriable errors → cooldown + failover.
+		if isRetriable(resp.StatusCode) {
+			bodyPreview := readPreview(resp.Body, 512)
 			resp.Body.Close()
 			h.Log.Warn("upstream rejected, failover",
 				"account", acct.Name, "account_id", acct.ID,
+				"provider", string(acct.Provider),
 				"path", r.URL.Path, "status", resp.StatusCode,
 				"latency_ms", latency.Milliseconds(), "preview", bodyPreview)
-			if resp.StatusCode == http.StatusTooManyRequests {
+			if shouldCooldown(resp.StatusCode, bodyPreview) {
 				h.Balancer.MarkCooldown(acct.ID)
 			}
 			lastErr = fmt.Errorf("upstream %d: %s", resp.StatusCode, bodyPreview)
@@ -172,17 +335,29 @@ func (h *Handler) proxyWithFailover(w http.ResponseWriter, r *http.Request, maxA
 		h.copyResponse(w, resp)
 		h.Log.Info("proxied",
 			"account", acct.Name, "account_id", acct.ID,
+			"provider", string(acct.Provider),
 			"path", r.URL.Path, "status", resp.StatusCode,
 			"latency_ms", latency.Milliseconds(), "stream", isStreaming(resp))
 		return
 	}
 
-	// Exhausted retries. Distinguish "everything is rate-limited" (→ 429) from
-	// "mixed upstream errors" (→ 502).
+	// Exhausted retries.
 	if h.Balancer.Len() > 0 {
 		allCooldown := true
 		status := h.Balancer.Status()
 		for _, a := range h.Balancer.Accounts() {
+			if eligible != nil && len(eligible) > 0 {
+				matched := false
+				for _, p := range eligible {
+					if a.Provider == p {
+						matched = true
+						break
+					}
+				}
+				if !matched {
+					continue
+				}
+			}
 			if !status[a.ID].InCooldown {
 				allCooldown = false
 				break
@@ -204,25 +379,21 @@ func (h *Handler) proxyWithFailover(w http.ResponseWriter, r *http.Request, maxA
 	writeError(w, http.StatusBadGateway, "all accounts failed")
 }
 
-// copyResponse streams the upstream response body to the client. For chunked /
-// SSE responses we flush after every read so tokens reach the client immediately.
+// copyResponse streams the upstream response body to the client.
 func (h *Handler) copyResponse(w http.ResponseWriter, resp *http.Response) {
 	defer resp.Body.Close()
-	// Copy headers (except hop-by-hop ones).
 	for k, vs := range resp.Header {
 		for _, v := range vs {
 			w.Header().Add(k, v)
 		}
 	}
 	w.WriteHeader(resp.StatusCode)
-
 	flusher, _ := w.(http.Flusher)
 	buf := make([]byte, 4096)
 	for {
 		n, err := resp.Body.Read(buf)
 		if n > 0 {
 			if _, werr := w.Write(buf[:n]); werr != nil {
-				// client went away; stop copying silently
 				return
 			}
 			if flusher != nil {
@@ -239,12 +410,12 @@ func (h *Handler) copyResponse(w http.ResponseWriter, resp *http.Response) {
 }
 
 // copyHeaders duplicates src into dst, dropping hop-by-hop headers and any
-// Authorization that the client may have sent (we always set our own).
+// Authorization the client may have sent.
 func copyHeaders(dst, src http.Header) {
 	hopByHop := []string{
 		"Connection", "Keep-Alive", "Proxy-Authenticate", "Proxy-Authorization",
 		"Te", "Trailers", "Transfer-Encoding", "Upgrade",
-		"Authorization", // always overwritten by the account key
+		"Authorization",
 	}
 	for k, vs := range src {
 		skip := false
@@ -263,8 +434,6 @@ func copyHeaders(dst, src http.Header) {
 	}
 }
 
-// readPreview reads up to n bytes from r and returns them as a string, always
-// closing the reader.
 func readPreview(r io.ReadCloser, n int) string {
 	defer r.Close()
 	buf := make([]byte, n)
@@ -272,21 +441,15 @@ func readPreview(r io.ReadCloser, n int) string {
 	return string(buf[:m])
 }
 
-// isStreaming reports whether the response is streaming (SSE or NDJSON/chunked).
 func isStreaming(resp *http.Response) bool {
 	ct := resp.Header.Get("Content-Type")
-	if strings.Contains(ct, "text/event-stream") {
-		return true
-	}
-	if strings.Contains(ct, "application/x-ndjson") {
+	if strings.Contains(ct, "text/event-stream") || strings.Contains(ct, "application/x-ndjson") {
 		return true
 	}
 	te := resp.Header.Get("Transfer-Encoding")
 	return strings.Contains(strings.ToLower(te), "chunked")
 }
 
-// writeError emits a JSON-formatted error to the client, mirroring Ollama's
-// error shape so OpenAI-compatible clients can parse it.
 func writeError(w http.ResponseWriter, status int, msg string) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(status)
diff --git a/internal/proxy/handler_test.go b/internal/proxy/handler_test.go
index 349613a..fa576b1 100644
--- a/internal/proxy/handler_test.go
+++ b/internal/proxy/handler_test.go
@@ -53,6 +53,12 @@ func (m *mockUpstream) handler(w http.ResponseWriter, r *http.Request) {
 
 func newTestHandler(t *testing.T, upstreamURL string, accounts []config.Account, retries int) *Handler {
 	t.Helper()
+	// Apply the mock upstream URL to any account without an explicit BaseURL.
+	for i := range accounts {
+		if accounts[i].BaseURL == "" {
+			accounts[i].BaseURL = upstreamURL
+		}
+	}
 	b := NewBalancer(accounts, 50*time.Millisecond)
 	return NewHandler(b, upstreamURL, retries, log.New("debug"))
 }
@@ -243,3 +249,198 @@ func TestIsAllowed(t *testing.T) {
 		}
 	}
 }
+
+// TestHandler_GoPathRoutesToGoProvider verifies /go/v1/* forces the
+// opencode-go provider and strips the /go prefix before forwarding upstream.
+func TestHandler_GoPathRoutesToGoProvider(t *testing.T) {
+	var seenPath, seenAuth string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		seenPath = r.URL.Path
+		seenAuth = r.Header.Get("Authorization")
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(200)
+		_, _ = io.WriteString(w, `{"ok":true}`)
+	}))
+	defer srv.Close()
+
+	accts := []config.Account{
+		{ID: "idO", Name: "o", APIKey: "kO", Provider: config.ProviderOllamaCloud, BaseURL: "http://unused-ollama"},
+		{ID: "idG", Name: "g", APIKey: "kG", Provider: config.ProviderOpenCodeGo, BaseURL: srv.URL},
+	}
+	h := newTestHandler(t, "http://unused", accts, 2)
+
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest("GET", "/go/v1/models", nil)
+	h.ServeHTTP(rec, req)
+
+	if rec.Code != 200 {
+		t.Fatalf("status = %d, want 200", rec.Code)
+	}
+	if seenPath != "/v1/models" {
+		t.Errorf("upstream path = %q, want /v1/models", seenPath)
+	}
+	if seenAuth != "Bearer kG" {
+		t.Errorf("upstream auth = %q, want go account key", seenAuth)
+	}
+}
+
+// TestHandler_ModelBasedRouting verifies a common model can be served by
+// either provider and a unique Go model routes only to Go accounts.
+func TestHandler_ModelBasedRouting(t *testing.T) {
+	ollamaSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(200)
+		_, _ = io.WriteString(w, `{"from":"ollama"}`)
+	}))
+	goSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(200)
+		_, _ = io.WriteString(w, `{"from":"go"}`)
+	}))
+	defer ollamaSrv.Close()
+	defer goSrv.Close()
+
+	accts := []config.Account{
+		{ID: "idO", Name: "o", APIKey: "kO", Provider: config.ProviderOllamaCloud, BaseURL: ollamaSrv.URL},
+		{ID: "idG", Name: "g", APIKey: "kG", Provider: config.ProviderOpenCodeGo, BaseURL: goSrv.URL},
+	}
+	h := newTestHandler(t, "http://unused", accts, 2)
+
+	// Unique Go model must route to the Go upstream.
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest("POST", "/v1/chat/completions",
+		strings.NewReader(`{"model":"mimo-v2.5","messages":[]}`))
+	h.ServeHTTP(rec, req)
+	if rec.Code != 200 {
+		t.Fatalf("mimo status = %d", rec.Code)
+	}
+	if !strings.Contains(rec.Body.String(), `"from":"go"`) {
+		t.Errorf("mimo routed to wrong upstream: %s", rec.Body.String())
+	}
+
+	// Unique Ollama model must route to the Ollama upstream.
+	rec = httptest.NewRecorder()
+	req = httptest.NewRequest("POST", "/v1/chat/completions",
+		strings.NewReader(`{"model":"gpt-oss:20b","messages":[]}`))
+	h.ServeHTTP(rec, req)
+	if rec.Code != 200 {
+		t.Fatalf("gpt-oss status = %d", rec.Code)
+	}
+	if !strings.Contains(rec.Body.String(), `"from":"ollama"`) {
+		t.Errorf("gpt-oss routed to wrong upstream: %s", rec.Body.String())
+	}
+}
+
+// TestHandler_MergedModels verifies /v1/models returns the union of both
+// catalogs with raw model IDs (no labels in the id field).
+func TestHandler_MergedModels(t *testing.T) {
+	accts := []config.Account{
+		{ID: "idO", Name: "o", APIKey: "kO", Provider: config.ProviderOllamaCloud, BaseURL: "http://unused"},
+		{ID: "idG", Name: "g", APIKey: "kG", Provider: config.ProviderOpenCodeGo, BaseURL: "http://unused"},
+	}
+	h := newTestHandler(t, "http://unused", accts, 2)
+
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest("GET", "/v1/models", nil)
+	h.ServeHTTP(rec, req)
+	if rec.Code != 200 {
+		t.Fatalf("status = %d", rec.Code)
+	}
+	body := rec.Body.String()
+	// Common model appears with raw ID (no label).
+	if !strings.Contains(body, `"id":"glm-5"`) {
+		t.Errorf("common model glm-5 missing from merged list")
+	}
+	// Unique Ollama model appears with raw ID (no label in id).
+	if !strings.Contains(body, `"id":"gpt-oss:20b"`) {
+		t.Errorf("unique ollama model missing: %s", body)
+	}
+	// Unique Go model appears with raw ID.
+	if !strings.Contains(body, `"id":"mimo-v2.5"`) {
+		t.Errorf("unique go model missing: %s", body)
+	}
+	// No labels should appear in any id field.
+	if strings.Contains(body, `(ollama)`) || strings.Contains(body, `(go)`) {
+		t.Errorf("labels should not appear in id field: %s", body)
+	}
+}
+
+// TestHandler_402UsageLimitTriggersFailover verifies 402 is treated as
+// retriable and triggers failover to the next account.
+func TestHandler_402UsageLimitTriggersFailover(t *testing.T) {
+	badSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(402)
+		_, _ = io.WriteString(w, `{"error":{"message":"usage limit exhausted"}}`)
+	}))
+	goodSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(200)
+		_, _ = io.WriteString(w, `{"ok":true}`)
+	}))
+	defer badSrv.Close()
+	defer goodSrv.Close()
+
+	accts := []config.Account{
+		{ID: "idA", Name: "a", APIKey: "k1", BaseURL: badSrv.URL},
+		{ID: "idB", Name: "b", APIKey: "k2", BaseURL: goodSrv.URL},
+	}
+	h := newTestHandler(t, "http://unused", accts, 2)
+
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest("GET", "/api/version", nil)
+	h.ServeHTTP(rec, req)
+	if rec.Code != 200 {
+		t.Fatalf("status = %d, want 200 after 402 failover", rec.Code)
+	}
+}
+
+// TestIsRetriable and TestShouldCooldown cover the retry classification.
+func TestIsRetriable(t *testing.T) {
+	retriable := []int{429, 402, 500, 502, 503, 408}
+	for _, s := range retriable {
+		if !isRetriable(s) {
+			t.Errorf("isRetriable(%d) = false, want true", s)
+		}
+	}
+	nonRetriable := []int{200, 400, 401, 403, 404, 422}
+	for _, s := range nonRetriable {
+		if isRetriable(s) {
+			t.Errorf("isRetriable(%d) = true, want false", s)
+		}
+	}
+}
+
+func TestShouldCooldown(t *testing.T) {
+	if !shouldCooldown(429, "rate limit") {
+		t.Error("429 should cooldown")
+	}
+	if !shouldCooldown(402, "usage limit") {
+		t.Error("402 should cooldown")
+	}
+	if shouldCooldown(500, "internal error") {
+		t.Error("500 should NOT cooldown")
+	}
+}
+
+func TestIsBillingDisable(t *testing.T) {
+	if !isBillingDisable("Insufficient credits for this account") {
+		t.Error("insufficient credits should be billing disable")
+	}
+	if !isBillingDisable("credit balance too low") {
+		t.Error("credit balance should be billing disable")
+	}
+	if isBillingDisable("usage limit exhausted") {
+		t.Error("usage limit exhausted should NOT be billing disable")
+	}
+}
+
+func TestRoutePath(t *testing.T) {
+	up, prov, isGo := routePath("/go/v1/models")
+	if up != "/v1/models" || prov != config.ProviderOpenCodeGo || !isGo {
+		t.Errorf("routePath(/go/v1/models) = %q,%v,%v", up, prov, isGo)
+	}
+	up, prov, isGo = routePath("/v1/models")
+	if up != "/v1/models" || prov != "" || isGo {
+		t.Errorf("routePath(/v1/models) = %q,%v,%v", up, prov, isGo)
+	}
+}
diff --git a/internal/proxy/model_router.go b/internal/proxy/model_router.go
new file mode 100644
index 0000000..6390b0d
--- /dev/null
+++ b/internal/proxy/model_router.go
@@ -0,0 +1,116 @@
+package proxy
+
+import (
+	"sort"
+
+	"github.com/Atte149/ollama-proxy/internal/config"
+)
+
+// ollamaCloudModels is the set of model IDs served by Ollama Cloud.
+// These overlap partly with the OpenCode Go catalog.
+var ollamaCloudModels = []string{
+	"deepseek-v3.1:671b", "deepseek-v3.2", "deepseek-v4-flash", "deepseek-v4-pro",
+	"devstral-2:123b", "devstral-small-2:24b",
+	"gemini-3-flash-preview", "gemma3:12b", "gemma3:27b", "gemma3:4b", "gemma4:31b",
+	"glm-4.7", "glm-5", "glm-5.1", "glm-5.2",
+	"gpt-oss:120b", "gpt-oss:20b",
+	"kimi-k2.5", "kimi-k2.6", "kimi-k2.7-code",
+	"minimax-m2.1", "minimax-m2.5", "minimax-m2.7", "minimax-m3",
+	"ministral-3:14b", "ministral-3:3b", "ministral-3:8b",
+	"mistral-large-3:675b",
+	"nemotron-3-nano:30b", "nemotron-3-super", "nemotron-3-ultra",
+	"qwen3-coder:480b", "qwen3-coder-next", "qwen3.5:397b",
+	"rnj-1:8b",
+}
+
+// openCodeGoModels is the set of model IDs served by OpenCode Go.
+var openCodeGoModels = []string{
+	"deepseek-v4-flash", "deepseek-v4-pro",
+	"glm-5", "glm-5.1", "glm-5.2",
+	"hy3-preview",
+	"kimi-k2.5", "kimi-k2.6", "kimi-k2.7-code",
+	"mimo-v2-omni", "mimo-v2-pro", "mimo-v2.5", "mimo-v2.5-pro",
+	"minimax-m2.5", "minimax-m2.7", "minimax-m3",
+	"qwen3.5-plus", "qwen3.6-plus", "qwen3.7-max", "qwen3.7-plus",
+}
+
+// modelProviders maps a model ID to the providers that can serve it.
+// Built once from the two catalogs above.
+var modelProviders = func() map[string][]config.ProviderType {
+	m := make(map[string][]config.ProviderType, len(ollamaCloudModels)+len(openCodeGoModels))
+	add := func(id string, p config.ProviderType) {
+		m[id] = append(m[id], p)
+	}
+	for _, id := range ollamaCloudModels {
+		add(id, config.ProviderOllamaCloud)
+	}
+	for _, id := range openCodeGoModels {
+		// Deduplicate: if already present (common model), append; else create.
+		found := false
+		for _, ex := range m[id] {
+			if ex == config.ProviderOpenCodeGo {
+				found = true
+				break
+			}
+		}
+		if !found {
+			add(id, config.ProviderOpenCodeGo)
+		}
+	}
+	return m
+}()
+
+// ProvidersForModel returns the providers eligible to serve the given model.
+// Unknown models default to Ollama Cloud (the original behaviour).
+func ProvidersForModel(model string) []config.ProviderType {
+	if ps, ok := modelProviders[model]; ok {
+		return ps
+	}
+	return []config.ProviderType{config.ProviderOllamaCloud}
+}
+
+// AllModels returns the deduplicated, sorted list of all model IDs known to the
+// router (union of both catalogs).
+func AllModels() []string {
+	seen := make(map[string]struct{})
+	for id := range modelProviders {
+		seen[id] = struct{}{}
+	}
+	out := make([]string, 0, len(seen))
+	for id := range seen {
+		out = append(out, id)
+	}
+	sort.Strings(out)
+	return out
+}
+
+// IsCommonModel reports whether the model is served by both providers.
+func IsCommonModel(model string) bool {
+	ps := ProvidersForModel(model)
+	if len(ps) < 2 {
+		return false
+	}
+	hasOllama, hasGo := false, false
+	for _, p := range ps {
+		switch p {
+		case config.ProviderOllamaCloud:
+			hasOllama = true
+		case config.ProviderOpenCodeGo:
+			hasGo = true
+		}
+	}
+	return hasOllama && hasGo
+}
+
+// ProviderLabel returns a short human label for a provider, used to annotate
+// unique models in the merged /v1/models response and in opencode config names.
+func ProviderLabel(p config.ProviderType) string {
+	switch p {
+	case config.ProviderOpenCodeGo:
+		return "go"
+	case config.ProviderOllamaCloud:
+		return "ollama"
+	default:
+		return string(p)
+	}
+}
diff --git a/internal/proxy/model_router_test.go b/internal/proxy/model_router_test.go
new file mode 100644
index 0000000..9e2a075
--- /dev/null
+++ b/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")
+	}
+}
diff --git a/internal/proxy/retry.go b/internal/proxy/retry.go
index e5c361d..bbe79c2 100644
--- a/internal/proxy/retry.go
+++ b/internal/proxy/retry.go
@@ -1,28 +1,63 @@
 package proxy
 
-// retry.go holds the failover helpers used by handler.go. The retry loop itself
-// lives inside Handler.proxyWithFailover (see handler.go) because it needs
-// tight control over the moment a response starts streaming vs. is rejected
-// pre-stream. This file documents the invariants the loop must maintain.
+import (
+	"net/http"
+	"strings"
+)
 
-// Streaming invariant
-// ===================
-// Once an upstream account has returned a 2xx status AND the proxy has started
-// writing the response body to the client (a single byte flushed), the request
-// is committed: we MUST NOT switch accounts for that request. Any mid-stream
-// upstream error is surfaced to the client as-is (truncated response); we never
-// attempt to "restart" a streamed request on a different account, because the
-// client has already received partial output and a retry would duplicate it.
+// isRetriable reports whether an upstream status code should trigger failover
+// to the next account before any bytes are streamed to the client.
 //
-// Pre-stream failover
-// -------------------
-// The window in which we CAN retry on another account is exactly:
-//   1. The upstream HTTP request returned an error (network, timeout, EOF
-//      before any response).
-//   2. The upstream returned 429 (Too Many Requests) — we mark the account
-//      cooldown and try the next.
-//   3. The upstream returned 5xx — we try the next account WITHOUT marking
-//      cooldown (5xx may be transient and is not necessarily a rate limit).
+// 429 — rate limit / usage limit (retryable cooldown)
+// 402 — payment required; treated as retryable when the body text matches a
 //
-// Once copyResponse has called WriteHeader, no further retries are possible
-// for this request.
+//	usage-window pattern ("usage limit", "limit reached", "exhausted",
+//	"daily/weekly/monthly limit"). A bare "insufficient credits" is also
+//	retriable (billing disable) — we still fail over, just with a longer
+//	cooldown.
+//
+// 5xx — transient server error
+// 408 — request timeout
+// Other 4xx are not retriable: the request is malformed or the model is
+// unknown, so retrying on another account would fail identically.
+func isRetriable(status int) bool {
+	switch {
+	case status == http.StatusTooManyRequests:
+		return true
+	case status == http.StatusPaymentRequired:
+		return true
+	case status >= 500:
+		return true
+	case status == http.StatusRequestTimeout:
+		return true
+	default:
+		return false
+	}
+}
+
+// shouldCooldown reports whether an account should be marked cooldown after a
+// retriable failure. 5xx does not trigger cooldown (the error may be
+// transient and unrelated to this account's quota). 429 and 402 always do.
+func shouldCooldown(status int, bodyPreview string) bool {
+	switch {
+	case status == http.StatusTooManyRequests:
+		return true
+	case status == http.StatusPaymentRequired:
+		return true
+	default:
+		return false
+	}
+}
+
+// isBillingDisable reports whether the error body indicates a billing/credit
+// exhaustion (longer cooldown) rather than a transient usage-window limit.
+// Used for logging/diagnostics; the cooldown duration is the same in v1.
+func isBillingDisable(bodyPreview string) bool {
+	low := strings.ToLower(bodyPreview)
+	for _, marker := range []string{"insufficient credits", "credit balance", "billing"} {
+		if strings.Contains(low, marker) {
+			return true
+		}
+	}
+	return false
+}