feat: add Vercel AI Gateway as a provider

Adds 'vercel' as a recognized provider throughout the model resolution
system, enabling users with Vercel AI Gateway to use it as a universal
fallback for OpenAI, Anthropic, and Google models.

The gateway transform infers the sub-provider from canonical model names
(claude->anthropic, gpt->openai, gemini->google) and delegates to the
appropriate provider-specific transform, producing model strings like
vercel/anthropic/claude-opus-4.6.

src/cli/config-manager/detect-current-config.ts

@@ -12,6 +12,7 @@ function detectProvidersFromOmoConfig(): {
   hasZaiCodingPlan: boolean
   hasKimiForCoding: boolean
   hasOpencodeGo: boolean
+  hasVercelAiGateway: boolean
 } {
   const omoConfigPath = getOmoConfigPath()
   if (!existsSync(omoConfigPath)) {
@@ -21,6 +22,7 @@ function detectProvidersFromOmoConfig(): {
       hasZaiCodingPlan: false,
       hasKimiForCoding: false,
       hasOpencodeGo: false,
+      hasVercelAiGateway: false,
     }
   }
 
@@ -34,6 +36,7 @@ function detectProvidersFromOmoConfig(): {
         hasZaiCodingPlan: false,
         hasKimiForCoding: false,
         hasOpencodeGo: false,
+        hasVercelAiGateway: false,
       }
     }
 
@@ -43,8 +46,9 @@ function detectProvidersFromOmoConfig(): {
     const hasZaiCodingPlan = configStr.includes('"zai-coding-plan/')
     const hasKimiForCoding = configStr.includes('"kimi-for-coding/')
     const hasOpencodeGo = configStr.includes('"opencode-go/')
+    const hasVercelAiGateway = configStr.includes('"vercel/')
 
-    return { hasOpenAI, hasOpencodeZen, hasZaiCodingPlan, hasKimiForCoding, hasOpencodeGo }
+    return { hasOpenAI, hasOpencodeZen, hasZaiCodingPlan, hasKimiForCoding, hasOpencodeGo, hasVercelAiGateway }
   } catch {
     return {
       hasOpenAI: true,
@@ -52,6 +56,7 @@ function detectProvidersFromOmoConfig(): {
       hasZaiCodingPlan: false,
       hasKimiForCoding: false,
       hasOpencodeGo: false,
+      hasVercelAiGateway: false,
     }
   }
 }
@@ -78,6 +83,7 @@ export function detectCurrentConfig(): DetectedConfig {
     hasZaiCodingPlan: false,
     hasKimiForCoding: false,
     hasOpencodeGo: false,
+    hasVercelAiGateway: false,
   }
 
   const { format, path } = detectConfigFormat()
@@ -106,12 +112,13 @@ export function detectCurrentConfig(): DetectedConfig {
   const providers = openCodeConfig.provider as Record<string, unknown> | undefined
   result.hasGemini = providers ? "google" in providers : false
 
-  const { hasOpenAI, hasOpencodeZen, hasZaiCodingPlan, hasKimiForCoding, hasOpencodeGo } = detectProvidersFromOmoConfig()
+  const { hasOpenAI, hasOpencodeZen, hasZaiCodingPlan, hasKimiForCoding, hasOpencodeGo, hasVercelAiGateway } = detectProvidersFromOmoConfig()
   result.hasOpenAI = hasOpenAI
   result.hasOpencodeZen = hasOpencodeZen
   result.hasZaiCodingPlan = hasZaiCodingPlan
   result.hasKimiForCoding = hasKimiForCoding
   result.hasOpencodeGo = hasOpencodeGo
+  result.hasVercelAiGateway = hasVercelAiGateway
 
   return result
 }

src/cli/install-validators.ts

@@ -40,6 +40,7 @@ export function formatConfigSummary(config: InstallConfig): string {
   lines.push(formatProvider("OpenCode Zen", config.hasOpencodeZen, "opencode/ models"))
   lines.push(formatProvider("Z.ai Coding Plan", config.hasZaiCodingPlan, "Librarian/Multimodal"))
   lines.push(formatProvider("Kimi For Coding", config.hasKimiForCoding, "Sisyphus/Prometheus fallback"))
+  lines.push(formatProvider("Vercel AI Gateway", config.hasVercelAiGateway, "universal proxy"))
 
   lines.push("")
   lines.push(color.dim("─".repeat(40)))
@@ -153,6 +154,10 @@ export function validateNonTuiArgs(args: InstallArgs): { valid: boolean; errors:
     errors.push(`Invalid --kimi-for-coding value: ${args.kimiForCoding} (expected: no, yes)`)
   }
 
+  if (args.vercelAiGateway !== undefined && !["no", "yes"].includes(args.vercelAiGateway)) {
+    errors.push(`Invalid --vercel-ai-gateway value: ${args.vercelAiGateway} (expected: no, yes)`)
+  }
+
   return { valid: errors.length === 0, errors }
 }
 
@@ -167,6 +172,7 @@ export function argsToConfig(args: InstallArgs): InstallConfig {
     hasZaiCodingPlan: args.zaiCodingPlan === "yes",
 hasKimiForCoding: args.kimiForCoding === "yes",
     hasOpencodeGo: args.opencodeGo === "yes",
+    hasVercelAiGateway: args.vercelAiGateway === "yes",
   }
 }
 
@@ -179,6 +185,7 @@ export function detectedToInitialValues(detected: DetectedConfig): {
   zaiCodingPlan: BooleanArg
 kimiForCoding: BooleanArg
   opencodeGo: BooleanArg
+  vercelAiGateway: BooleanArg
 } {
   let claude: ClaudeSubscription = "no"
   if (detected.hasClaude) {
@@ -194,5 +201,6 @@ kimiForCoding: BooleanArg
     zaiCodingPlan: detected.hasZaiCodingPlan ? "yes" : "no",
 kimiForCoding: detected.hasKimiForCoding ? "yes" : "no",
     opencodeGo: detected.hasOpencodeGo ? "yes" : "no",
+    vercelAiGateway: detected.hasVercelAiGateway ? "yes" : "no",
   }
 }

src/cli/model-fallback-types.ts

@@ -11,6 +11,7 @@ export interface ProviderAvailability {
 	zai: boolean
 kimiForCoding: boolean
 	opencodeGo: boolean
+	vercelAiGateway: boolean
 	isMaxPlan: boolean
 }
 

src/cli/model-fallback.ts

@@ -105,7 +105,8 @@ export function generateModelConfig(config: InstallConfig): GeneratedOmoConfig {
     avail.copilot ||
     avail.zai ||
     avail.kimiForCoding ||
-    avail.opencodeGo
+    avail.opencodeGo ||
+    avail.vercelAiGateway
   if (!hasAnyProvider) {
     return {
       $schema: SCHEMA_URL,
@@ -130,6 +131,8 @@ export function generateModelConfig(config: InstallConfig): GeneratedOmoConfig {
         agentConfig = { model: "opencode-go/minimax-m2.7" }
       } else if (avail.zai) {
         agentConfig = { model: ZAI_MODEL }
+      } else if (avail.vercelAiGateway) {
+        agentConfig = { model: "vercel/anthropic/claude-haiku-4.5" }
       }
       if (agentConfig) {
         agents[role] = attachAllFallbackModels(agentConfig, req.fallbackChain, avail)
@@ -145,6 +148,8 @@ export function generateModelConfig(config: InstallConfig): GeneratedOmoConfig {
         agentConfig = { model: "opencode/claude-haiku-4-5" }
       } else if (avail.opencodeGo) {
         agentConfig = { model: "opencode-go/minimax-m2.7" }
+      } else if (avail.vercelAiGateway) {
+        agentConfig = { model: "vercel/anthropic/claude-haiku-4.5" }
       } else if (avail.copilot) {
         agentConfig = { model: "github-copilot/gpt-5-mini" }
       } else {

src/cli/provider-availability.ts

@@ -13,6 +13,7 @@ export function toProviderAvailability(config: InstallConfig): ProviderAvailabil
 		zai: config.hasZaiCodingPlan,
 kimiForCoding: config.hasKimiForCoding,
 		opencodeGo: config.hasOpencodeGo,
+		vercelAiGateway: config.hasVercelAiGateway,
 		isMaxPlan: config.isMax20,
 	}
 }
@@ -27,6 +28,7 @@ export function isProviderAvailable(provider: string, availability: ProviderAvai
 		"zai-coding-plan": availability.zai,
 "kimi-for-coding": availability.kimiForCoding,
 		"opencode-go": availability.opencodeGo,
+		vercel: availability.vercelAiGateway,
 	}
 	return mapping[provider] ?? false
 }

src/cli/tui-install-prompts.ts

@@ -110,6 +110,16 @@ export async function promptInstallConfig(detected: DetectedConfig): Promise<Ins
   })
   if (!opencodeGo) return null
 
+  const vercelAiGateway = await selectOrCancel({
+    message: "Do you have a Vercel AI Gateway API key?",
+    options: [
+      { value: "no", label: "No", hint: "Will use other configured providers" },
+      { value: "yes", label: "Yes", hint: "Universal proxy for OpenAI, Anthropic, Google, etc." },
+    ],
+    initialValue: initial.vercelAiGateway,
+  })
+  if (!vercelAiGateway) return null
+
   return {
     hasClaude: claude !== "no",
     isMax20: claude === "max20",
@@ -120,5 +130,6 @@ export async function promptInstallConfig(detected: DetectedConfig): Promise<Ins
     hasZaiCodingPlan: zaiCodingPlan === "yes",
     hasKimiForCoding: kimiForCoding === "yes",
     hasOpencodeGo: opencodeGo === "yes",
+    hasVercelAiGateway: vercelAiGateway === "yes",
   }
 }

src/cli/types.ts

@@ -11,6 +11,7 @@ export interface InstallArgs {
   zaiCodingPlan?: BooleanArg
 kimiForCoding?: BooleanArg
   opencodeGo?: BooleanArg
+  vercelAiGateway?: BooleanArg
   skipAuth?: boolean
 }
 
@@ -24,6 +25,7 @@ export interface InstallConfig {
   hasZaiCodingPlan: boolean
   hasKimiForCoding: boolean
   hasOpencodeGo: boolean
+  hasVercelAiGateway: boolean
 }
 
 export interface ConfigMergeResult {
@@ -44,4 +46,5 @@ export interface DetectedConfig {
   hasZaiCodingPlan: boolean
   hasKimiForCoding: boolean
   hasOpencodeGo: boolean
+  hasVercelAiGateway: boolean
 }