diff --git a/src/renderer/src/components/onboarding/onboarding-folder-agent-startup.test.ts b/src/renderer/src/components/onboarding/onboarding-folder-agent-startup.test.ts
index 1e5710260..180688173 100644
--- a/src/renderer/src/components/onboarding/onboarding-folder-agent-startup.test.ts
+++ b/src/renderer/src/components/onboarding/onboarding-folder-agent-startup.test.ts
@@ -14,8 +14,7 @@ describe('buildOnboardingFolderAgentStartup', () => {
     })
 
     expect(startup).toEqual({
-      command:
-        "codex '-m' 'gpt-5.6-sol' '-c' 'model_reasoning_effort=medium' '--dangerously-bypass-approvals-and-sandbox'",
+      command: "codex '--dangerously-bypass-approvals-and-sandbox'",
       env: {},
       launchAgent: 'codex',
       launchConfig: {
@@ -23,7 +22,7 @@ describe('buildOnboardingFolderAgentStartup', () => {
         agentArgs: '--dangerously-bypass-approvals-and-sandbox',
         agentEnv: {}
       },
-      sessionOptions: { model: 'gpt-5.6-sol', effort: 'medium' },
+      sessionOptions: undefined,
       telemetry: {
         agent_kind: 'codex',
         launch_source: 'onboarding',
@@ -99,8 +98,7 @@ describe('buildOnboardingFolderAgentStartup', () => {
         false
       )
     ).toEqual({
-      command:
-        "echo onboarding-folder-agent '-m' 'gpt-5.6-sol' '-c' 'model_reasoning_effort=medium' '--dangerously-bypass-approvals-and-sandbox'",
+      command: "echo onboarding-folder-agent '--dangerously-bypass-approvals-and-sandbox'",
       env: {},
       launchAgent: 'codex',
       launchConfig: {
@@ -108,7 +106,7 @@ describe('buildOnboardingFolderAgentStartup', () => {
         agentArgs: '--dangerously-bypass-approvals-and-sandbox',
         agentEnv: {}
       },
-      sessionOptions: { model: 'gpt-5.6-sol', effort: 'medium' },
+      sessionOptions: undefined,
       telemetry: {
         agent_kind: 'codex',
         launch_source: 'onboarding',
diff --git a/src/renderer/src/lib/launch-agent-in-new-tab.test.ts b/src/renderer/src/lib/launch-agent-in-new-tab.test.ts
index b3c5029a3..c43f98ef9 100644
--- a/src/renderer/src/lib/launch-agent-in-new-tab.test.ts
+++ b/src/renderer/src/lib/launch-agent-in-new-tab.test.ts
@@ -340,8 +340,7 @@ describe('launchAgentInNewTab', () => {
       environmentId: 'web-runtime',
       targetGroupId: 'group-1',
       activate: true,
-      command:
-        "codex '-m' 'gpt-5.6-sol' '-c' 'model_reasoning_effort=medium' '--model' 'gpt-5' '--reasoning-effort' 'high' 'fix the spinner'",
+      command: "codex '--model' 'gpt-5' '--reasoning-effort' 'high' 'fix the spinner'",
       env: { CODEX_PROFILE: 'captured' },
       startupCommandDelivery: 'shell-ready',
       launchConfig: {
@@ -486,8 +485,7 @@ describe('launchAgentInNewTab', () => {
     expect(mockQueueTabStartupCommand).toHaveBeenCalledWith(
       'tab-1',
       expect.objectContaining({
-        command:
-          "claude '--model' 'sonnet' '--effort' 'high' '--dangerously-skip-permissions' --prefill 'review Bob''s change'"
+        command: "claude '--dangerously-skip-permissions' --prefill 'review Bob''s change'"
       })
     )
   })
@@ -505,7 +503,7 @@ describe('launchAgentInNewTab', () => {
     expect(mockQueueTabStartupCommand).toHaveBeenCalledWith(
       'tab-1',
       expect.objectContaining({
-        command: 'claude "--model" "sonnet" "--effort" "high" "--dangerously-skip-permissions"'
+        command: 'claude "--dangerously-skip-permissions"'
       })
     )
   })
@@ -523,7 +521,7 @@ describe('launchAgentInNewTab', () => {
     expect(mockQueueTabStartupCommand).toHaveBeenCalledWith(
       'tab-1',
       expect.objectContaining({
-        command: "claude '--model' 'sonnet' '--effort' 'high' '--dangerously-skip-permissions'"
+        command: "claude '--dangerously-skip-permissions'"
       })
     )
   })
@@ -543,8 +541,7 @@ describe('launchAgentInNewTab', () => {
     expect(mockQueueTabStartupCommand).toHaveBeenCalledWith(
       'tab-1',
       expect.objectContaining({
-        command:
-          'codex "-m" "gpt-5.6-sol" "-c" "model_reasoning_effort=medium" "--model" "gpt-5" "fix the spinner"'
+        command: 'codex "--model" "gpt-5" "fix the spinner"'
       })
     )
   })
@@ -564,8 +561,7 @@ describe('launchAgentInNewTab', () => {
     expect(mockQueueTabStartupCommand).toHaveBeenCalledWith(
       'tab-1',
       expect.objectContaining({
-        command:
-          "claude '--model' 'sonnet' '--effort' 'high' '--dangerously-skip-permissions' --prefill 'review Bob'\\''s change'"
+        command: "claude '--dangerously-skip-permissions' --prefill 'review Bob'\\''s change'"
       })
     )
   })
@@ -583,7 +579,7 @@ describe('launchAgentInNewTab', () => {
     expect(mockQueueTabStartupCommand).toHaveBeenCalledWith(
       'tab-1',
       expect.objectContaining({
-        command: "claude '--model' 'sonnet' '--effort' 'high' '--dangerously-skip-permissions'"
+        command: "claude '--dangerously-skip-permissions'"
       })
     )
   })
@@ -620,8 +616,7 @@ describe('launchAgentInNewTab', () => {
     expect(mockQueueTabStartupCommand).toHaveBeenCalledWith(
       'tab-1',
       expect.objectContaining({
-        command:
-          "claude '--model' 'sonnet' '--effort' 'high' '--dangerously-skip-permissions' --prefill 'review Bob'\\''s change'"
+        command: "claude '--dangerously-skip-permissions' --prefill 'review Bob'\\''s change'"
       })
     )
   })
@@ -642,7 +637,7 @@ describe('launchAgentInNewTab', () => {
     expect(mockQueueTabStartupCommand).toHaveBeenCalledWith(
       'tab-1',
       expect.objectContaining({
-        command: "claude '--model' 'sonnet' '--effort' 'high' '--dangerously-skip-permissions'"
+        command: "claude '--dangerously-skip-permissions'"
       })
     )
     expect(mockPasteDraftWhenAgentReady).toHaveBeenCalledWith(
@@ -848,7 +843,7 @@ describe('launchAgentInNewTab', () => {
     expect(mockQueueTabStartupCommand).toHaveBeenCalledWith(
       'tab-1',
       expect.objectContaining({
-        command: "codex '-m' 'gpt-5.6-sol' '-c' 'model_reasoning_effort=medium' '--model' 'gpt-5.5'"
+        command: "codex '--model' 'gpt-5.5'"
       })
     )
   })
diff --git a/src/renderer/src/lib/launch-work-item-direct.test.ts b/src/renderer/src/lib/launch-work-item-direct.test.ts
index 9eedb05be..c76c91bc0 100644
--- a/src/renderer/src/lib/launch-work-item-direct.test.ts
+++ b/src/renderer/src/lib/launch-work-item-direct.test.ts
@@ -402,7 +402,7 @@ describe('launchWorkItemDirect', () => {
       cmdOverrides: {},
       agentArgs: '--dangerously-skip-permissions',
       agentEnv: {},
-      sessionOptions: { model: 'sonnet', effort: 'high' },
+      sessionOptions: undefined,
       platform: 'win32',
       isRemote: false
     })
@@ -526,7 +526,7 @@ describe('launchWorkItemDirect', () => {
       cmdOverrides: {},
       agentArgs: '--yolo',
       agentEnv: {},
-      sessionOptions: { model: 'auto' },
+      sessionOptions: undefined,
       platform: 'linux',
       isRemote: true
     })
@@ -536,7 +536,7 @@ describe('launchWorkItemDirect', () => {
       cmdOverrides: {},
       agentArgs: '--yolo',
       agentEnv: {},
-      sessionOptions: { model: 'auto' },
+      sessionOptions: undefined,
       platform: 'linux',
       isRemote: true,
       allowEmptyPromptLaunch: true
diff --git a/src/renderer/src/lib/worktree-activation-created-agent.test.ts b/src/renderer/src/lib/worktree-activation-created-agent.test.ts
index 89fcb83c9..dfa23851a 100644
--- a/src/renderer/src/lib/worktree-activation-created-agent.test.ts
+++ b/src/renderer/src/lib/worktree-activation-created-agent.test.ts
@@ -96,8 +96,7 @@ describe('activateAndRevealWorktree created agent reopen', () => {
     expect(result).toEqual({ primaryTabId: reopenedTab?.id })
     expect(reopenedTab).toBeDefined()
     expect(state.pendingStartupByTabId[reopenedTab!.id]).toEqual({
-      command:
-        "codex '-m' 'gpt-5.6-sol' '-c' 'model_reasoning_effort=medium' '--dangerously-bypass-approvals-and-sandbox'",
+      command: "codex '--dangerously-bypass-approvals-and-sandbox'",
       env: {},
       launchAgent: 'codex',
       launchConfig: {
@@ -106,7 +105,7 @@ describe('activateAndRevealWorktree created agent reopen', () => {
         agentEnv: {}
       },
       launchToken: expect.any(String),
-      sessionOptions: { model: 'gpt-5.6-sol', effort: 'medium' },
+      sessionOptions: undefined,
       telemetry: {
         agent_kind: 'codex',
         launch_source: 'sidebar',
diff --git a/src/renderer/src/store/slices/repos-onboarding-folder-startup.test.ts b/src/renderer/src/store/slices/repos-onboarding-folder-startup.test.ts
index b5c44f9ca..18f6cfb1f 100644
--- a/src/renderer/src/store/slices/repos-onboarding-folder-startup.test.ts
+++ b/src/renderer/src/store/slices/repos-onboarding-folder-startup.test.ts
@@ -58,8 +58,7 @@ describe('repo slice skipped-onboarding folder startup', () => {
       {
         sidebarRevealBehavior: 'auto',
         startup: {
-          command:
-            "codex '-m' 'gpt-5.6-sol' '-c' 'model_reasoning_effort=medium' '--dangerously-bypass-approvals-and-sandbox'",
+          command: "codex '--dangerously-bypass-approvals-and-sandbox'",
           env: {},
           launchAgent: 'codex',
           launchConfig: {
@@ -67,7 +66,7 @@ describe('repo slice skipped-onboarding folder startup', () => {
             agentArgs: '--dangerously-bypass-approvals-and-sandbox',
             agentEnv: {}
           },
-          sessionOptions: { model: 'gpt-5.6-sol', effort: 'medium' },
+          sessionOptions: undefined,
           telemetry: {
             agent_kind: 'codex',
             launch_source: 'onboarding',
diff --git a/src/shared/agent-session-option-catalog.test.ts b/src/shared/agent-session-option-catalog.test.ts
index c4e7eca14..ffabb087e 100644
--- a/src/shared/agent-session-option-catalog.test.ts
+++ b/src/shared/agent-session-option-catalog.test.ts
@@ -72,7 +72,7 @@ describe('agent session option catalog', () => {
     })
   })
 
-  it('restores defaults per model without leaking values across models', () => {
+  it('resolves only stored values without leaking values across models', () => {
     let persisted = updateNativeChatSessionOptionDefaults({
       persisted: undefined,
       agent: 'claude',
@@ -96,17 +96,56 @@ describe('agent session option catalog', () => {
     })
 
     expect(resolveNativeChatSessionOptionDefaults(persisted, 'claude')).toEqual({
-      model: 'sonnet',
-      effort: 'high'
+      model: 'sonnet'
     })
     expect(persisted.claude?.valuesByModel?.opus).toEqual({ effort: 'xhigh' })
   })
 
-  it('seeds a fresh launch from the catalog defaults', () => {
-    expect(resolveNativeChatSessionOptionDefaults(undefined, 'claude')).toEqual({
-      model: 'sonnet',
-      effort: 'high'
-    })
+  it('spawns vanilla when the user has not explicitly selected a model', () => {
+    // Regression (#9085): a fresh launch must not force the catalog default
+    // model/effort — the agent must spawn exactly as its own CLI would.
+    expect(resolveNativeChatSessionOptionDefaults(undefined, 'claude')).toBeUndefined()
+    expect(resolveNativeChatSessionOptionDefaults({}, 'claude')).toBeUndefined()
     expect(resolveNativeChatSessionOptionDefaults({}, 'future-agent')).toBeUndefined()
   })
+
+  it('resolves an explicitly selected model and only its stored options', () => {
+    let persisted = updateNativeChatSessionOptionDefaults({
+      persisted: undefined,
+      agent: 'claude',
+      modelId: 'opus',
+      optionId: 'model',
+      value: 'opus'
+    })
+    expect(resolveNativeChatSessionOptionDefaults(persisted, 'claude')).toEqual({
+      model: 'opus'
+    })
+    persisted = updateNativeChatSessionOptionDefaults({
+      persisted,
+      agent: 'claude',
+      modelId: 'opus',
+      optionId: 'effort',
+      value: 'xhigh'
+    })
+    expect(resolveNativeChatSessionOptionDefaults(persisted, 'claude')).toEqual({
+      model: 'opus',
+      effort: 'xhigh'
+    })
+  })
+
+  it('keeps catalog option defaults after the user explicitly selects a model', () => {
+    const persisted = updateNativeChatSessionOptionDefaults({
+      persisted: undefined,
+      agent: 'claude',
+      modelId: 'sonnet',
+      optionId: 'model',
+      value: 'sonnet'
+    })
+    const defaults = resolveNativeChatSessionOptionDefaults(persisted, 'claude')
+
+    expect(resolveAgentSessionOptionLaunch('claude', defaults)).toEqual({
+      args: ['--model', 'sonnet', '--effort', 'high'],
+      appliedValues: { model: 'sonnet', effort: 'high' }
+    })
+  })
 })
diff --git a/src/shared/native-chat-session-option-defaults.ts b/src/shared/native-chat-session-option-defaults.ts
index 98bd01871..5edc3c491 100644
--- a/src/shared/native-chat-session-option-defaults.ts
+++ b/src/shared/native-chat-session-option-defaults.ts
@@ -1,10 +1,5 @@
 import type { AgentType } from './agent-status-types'
-import {
-  catalogDefaultModel,
-  findCatalogModel,
-  getAgentSessionOptionCatalog,
-  sessionOptionValueIsValid
-} from './agent-session-option-catalog'
+import { sessionOptionValueIsValid } from './agent-session-option-catalog'
 import type {
   PersistedNativeChatSessionOptions,
   SessionOptionValue
@@ -14,16 +9,10 @@ export function resolveNativeChatSessionOptionDefaults(
   persisted: PersistedNativeChatSessionOptions | null | undefined,
   agent: AgentType
 ): Record<string, SessionOptionValue> | undefined {
-  const catalog = getAgentSessionOptionCatalog(agent)
   const entry = persisted?.[agent]
-  // Why: fresh launches must be authoritative too, so resolve the catalog's
-  // declared fallback before the launch command is assembled.
-  const modelId =
-    typeof entry?.model === 'string' && entry.model.trim()
-      ? entry.model
-      : catalog
-        ? catalogDefaultModel(catalog)?.id
-        : undefined
+  // Why: untouched settings must preserve the agent CLI's configured defaults;
+  // only a model explicitly selected by the user authorizes launch flags.
+  const modelId = typeof entry?.model === 'string' && entry.model.trim() ? entry.model : undefined
   if (!modelId) {
     return undefined
   }
@@ -36,11 +25,6 @@ export function resolveNativeChatSessionOptionDefaults(
       }
     }
   }
-
-  const model = catalog ? findCatalogModel(catalog, modelId) : undefined
-  for (const option of model?.options ?? []) {
-    values[option.id] ??= option.kind.defaultValue
-  }
   return values
 }