refactor: remove dead ultrawork model override code

Remove ultrawork-model-override hook and per-agent ultrawork model swap
config that relied on zen opencode.ai free tier (no longer functional).

Removed:
- src/hooks/ultrawork-model-override/ (hook, test, index)
- ultrawork field from AgentOverrideConfigSchema
- ultrawork-model-override from HookNameSchema
- UltraworkConfig type from model-fallback-types
- Non-max20 sonnet+ultrawork-opus codepath from model-fallback
- Claude subscription model table from installation docs
- All references in plugin-interface, create-session-hooks, schema.json
- Related test cases and updated snapshots

src/cli/__snapshots__/model-fallback.test.ts.snap

@@ -94,11 +94,7 @@ exports[`generateModelConfig single native provider uses Claude models when only
       "variant": "max",
     },
     "sisyphus": {
-      "model": "anthropic/claude-sonnet-4-6",
-      "ultrawork": {
-        "model": "anthropic/claude-opus-4-6",
-        "variant": "max",
-      },
+      "model": "anthropic/claude-opus-4-6",
       "variant": "max",
     },
   },
@@ -483,11 +479,7 @@ exports[`generateModelConfig all native providers uses preferred models from fal
       "variant": "max",
     },
     "sisyphus": {
-      "model": "anthropic/claude-sonnet-4-6",
-      "ultrawork": {
-        "model": "anthropic/claude-opus-4-6",
-        "variant": "max",
-      },
+      "model": "anthropic/claude-opus-4-6",
       "variant": "max",
     },
   },
@@ -1044,11 +1036,7 @@ exports[`generateModelConfig mixed provider scenarios uses Claude + OpenCode Zen
       "variant": "max",
     },
     "sisyphus": {
-      "model": "anthropic/claude-sonnet-4-6",
-      "ultrawork": {
-        "model": "anthropic/claude-opus-4-6",
-        "variant": "max",
-      },
+      "model": "anthropic/claude-opus-4-6",
       "variant": "max",
     },
   },
@@ -1192,11 +1180,7 @@ exports[`generateModelConfig mixed provider scenarios uses Claude + ZAI combinat
       "variant": "max",
     },
     "sisyphus": {
-      "model": "anthropic/claude-sonnet-4-6",
-      "ultrawork": {
-        "model": "anthropic/claude-opus-4-6",
-        "variant": "max",
-      },
+      "model": "anthropic/claude-opus-4-6",
       "variant": "max",
     },
   },
@@ -1257,11 +1241,7 @@ exports[`generateModelConfig mixed provider scenarios uses Gemini + Claude combi
       "variant": "max",
     },
     "sisyphus": {
-      "model": "anthropic/claude-sonnet-4-6",
-      "ultrawork": {
-        "model": "anthropic/claude-opus-4-6",
-        "variant": "max",
-      },
+      "model": "anthropic/claude-opus-4-6",
       "variant": "max",
     },
   },
@@ -1405,11 +1385,7 @@ exports[`generateModelConfig mixed provider scenarios uses all providers togethe
       "variant": "max",
     },
     "sisyphus": {
-      "model": "anthropic/claude-sonnet-4-6",
-      "ultrawork": {
-        "model": "anthropic/claude-opus-4-6",
-        "variant": "max",
-      },
+      "model": "anthropic/claude-opus-4-6",
       "variant": "max",
     },
   },

src/cli/config-manager.test.ts

@@ -240,52 +240,6 @@ describe("config-manager ANTIGRAVITY_PROVIDER_CONFIG", () => {
 })
 
 describe("generateOmoConfig - model fallback system", () => {
-  test("generates sonnet model with ultrawork opus for Claude standard subscription", () => {
-    // #given user has Claude standard subscription (not max20)
-    const config: InstallConfig = {
-      hasClaude: true,
-      isMax20: false,
-      hasOpenAI: false,
-      hasGemini: false,
-      hasCopilot: false,
-      hasOpencodeZen: false,
-      hasZaiCodingPlan: false,
-      hasKimiForCoding: false,
-    }
-
-    // #when generating config
-    const result = generateOmoConfig(config)
-
-    // #then Sisyphus uses sonnet for daily driving with ultrawork opus override
-    const sisyphus = (result.agents as Record<string, { model: string; variant?: string; ultrawork?: { model: string; variant?: string } }>).sisyphus
-    expect(result.$schema).toBe("https://raw.githubusercontent.com/code-yeongyu/oh-my-opencode/master/assets/oh-my-opencode.schema.json")
-    expect(sisyphus.model).toBe("anthropic/claude-sonnet-4-6")
-    expect(sisyphus.variant).toBe("max")
-    expect(sisyphus.ultrawork).toEqual({ model: "anthropic/claude-opus-4-6", variant: "max" })
-  })
-
-  test("generates native opus models without ultrawork when Claude max20 subscription", () => {
-    // #given user has Claude max20 subscription
-    const config: InstallConfig = {
-      hasClaude: true,
-      isMax20: true,
-      hasOpenAI: false,
-      hasGemini: false,
-      hasCopilot: false,
-      hasOpencodeZen: false,
-      hasZaiCodingPlan: false,
-      hasKimiForCoding: false,
-    }
-
-    // #when generating config
-    const result = generateOmoConfig(config)
-
-    // #then Sisyphus uses opus directly, no ultrawork override needed
-    const sisyphus = (result.agents as Record<string, { model: string; ultrawork?: unknown }>).sisyphus
-    expect(sisyphus.model).toBe("anthropic/claude-opus-4-6")
-    expect(sisyphus.ultrawork).toBeUndefined()
-  })
-
   test("uses github-copilot sonnet fallback when only copilot available", () => {
     // #given user has only copilot (no max plan)
     const config: InstallConfig = {

src/cli/model-fallback-types.ts

@@ -11,15 +11,9 @@ export interface ProviderAvailability {
 	isMaxPlan: boolean
 }
 
-export interface UltraworkConfig {
-	model: string
-	variant?: string
-}
-
 export interface AgentConfig {
 	model: string
 	variant?: string
-	ultrawork?: UltraworkConfig
 }
 
 export interface CategoryConfig {

src/cli/model-fallback.ts

@@ -76,15 +76,6 @@ export function generateModelConfig(config: InstallConfig): GeneratedOmoConfig {
         continue
       }
 
-      if (avail.native.claude && !avail.isMaxPlan) {
-        agents[role] = {
-          model: "anthropic/claude-sonnet-4-6",
-          variant: "max",
-          ultrawork: { model: "anthropic/claude-opus-4-6", variant: "max" },
-        }
-        continue
-      }
-
       const resolved = resolveModelFromChain(fallbackChain, avail)
       if (resolved) {
         const variant = resolved.variant ?? req.variant