fix(vscode): preserve agent override clear semantics

packages/kilo-vscode/src/KiloProvider.ts

@@ -1910,32 +1910,41 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
     // races with the async config.update() write on the CLI backend).
     this.pending++
     try {
-      await this.client.global.config.update({ config: partial }, { throwOnError: true })
+      try {
+        await this.client.global.config.update({ config: partial }, { throwOnError: true })
+      } catch (error) {
+        console.error("[Kilo New] KiloProvider: Failed to update config:", error)
+        this.postMessage({
+          type: "error",
+          message: getErrorMessage(error) || "Failed to update config",
+        })
+        this.postMessage({
+          type: "configSaveFailed",
+          config: (this.cachedConfigMessage as { config: unknown } | undefined)?.config ?? {},
+        })
+        return
+      }
 
-      // Re-fetch the full merged config (global + project + all layers) so the
-      // webview receives the complete resolved config, not just global-only data.
-      // Config.state is reset by updateGlobal (via Instance.resetStateEntry) so
-      // config.get() returns fresh data without a full dispose cycle.
-      const dir = this.getWorkspaceDirectory()
-      const { data: merged } = await this.client.config.get({ directory: dir }, { throwOnError: true })
+      try {
+        // Re-fetch the full merged config (global + project + all layers) so the
+        // webview receives the complete resolved config, not just global-only data.
+        // Config.state is reset by updateGlobal (via Instance.resetStateEntry) so
+        // config.get() returns fresh data without a full dispose cycle.
+        const dir = this.getWorkspaceDirectory()
+        const { data: merged } = await this.client.config.get({ directory: dir }, { throwOnError: true })
 
-      this.cachedConfigMessage = { type: "configLoaded", config: merged }
-      this.postMessage({ type: "configUpdated", config: merged })
+        this.cachedConfigMessage = { type: "configLoaded", config: merged }
+        this.postMessage({ type: "configUpdated", config: merged })
+      } catch (error) {
+        console.error("[Kilo New] KiloProvider: Failed to fetch merged config after update:", error)
+        // The write already succeeded; keep the optimistic state and wait for
+        // the SSE-driven refresh to deliver the authoritative merged config.
+        this.postMessage({ type: "configSaved" })
+      }
 
       if (refreshProviders) {
         await this.fetchAndSendProviders()
       }
-    } catch (error) {
-      console.error("[Kilo New] KiloProvider: Failed to update config:", error)
-      this.postMessage({
-        type: "error",
-        message: getErrorMessage(error) || "Failed to update config",
-      })
-      // Send configUpdated with the last known good config so the webview
-      // clears its saving flag and reverts optimistic state.
-      if (this.cachedConfigMessage) {
-        this.postMessage({ type: "configUpdated", config: (this.cachedConfigMessage as { config: unknown }).config })
-      }
     } finally {
       this.pending--
     }

packages/kilo-vscode/tests/unit/agent-behaviour-patches.test.ts

@@ -0,0 +1,55 @@
+import { describe, expect, it } from "bun:test"
+import {
+  selectedAgentNumberOverrideValue,
+  selectedAgentTextOverrideValue,
+  selectedDefaultAgentValue,
+  shouldClearDefaultAgentWhenAgentBecomesUnavailable,
+} from "../../webview-ui/src/components/settings/agent-behaviour-patches"
+
+describe("selectedAgentTextOverrideValue", () => {
+  it("maps an empty text field value to a null delete sentinel", () => {
+    expect(selectedAgentTextOverrideValue("")).toBeNull()
+  })
+
+  it("preserves a non-empty text override", () => {
+    expect(selectedAgentTextOverrideValue("Review code")).toBe("Review code")
+  })
+})
+
+describe("selectedAgentNumberOverrideValue", () => {
+  it("maps a blank numeric field value to a null delete sentinel", () => {
+    expect(selectedAgentNumberOverrideValue("", parseFloat)).toBeNull()
+  })
+
+  it("preserves a valid numeric override", () => {
+    expect(selectedAgentNumberOverrideValue("0.7", parseFloat)).toBe(0.7)
+  })
+
+  it("keeps invalid non-empty numeric input out of the persisted patch", () => {
+    expect(selectedAgentNumberOverrideValue("abc", parseFloat)).toBeUndefined()
+  })
+})
+
+describe("selectedDefaultAgentValue", () => {
+  it("maps an empty dropdown value to a null delete sentinel", () => {
+    expect(selectedDefaultAgentValue("")).toBeNull()
+  })
+
+  it("preserves a non-empty agent selection", () => {
+    expect(selectedDefaultAgentValue("code")).toBe("code")
+  })
+})
+
+describe("shouldClearDefaultAgentWhenAgentBecomesUnavailable", () => {
+  it("clears when the current default agent becomes unavailable", () => {
+    expect(shouldClearDefaultAgentWhenAgentBecomesUnavailable(true, "code", "code")).toBe(true)
+  })
+
+  it("does not clear when toggling a non-default agent", () => {
+    expect(shouldClearDefaultAgentWhenAgentBecomesUnavailable(true, "code", "plan")).toBe(false)
+  })
+
+  it("does not clear when the agent remains available", () => {
+    expect(shouldClearDefaultAgentWhenAgentBecomesUnavailable(false, "code", "code")).toBe(false)
+  })
+})

packages/kilo-vscode/tests/unit/config-utils.test.ts

@@ -189,6 +189,71 @@ describe("ConfigState", () => {
       expect(s.saving).toBe(false)
       expect(Object.keys(s.draft).length).toBe(0)
     })
+
+    it("preserves the null delete sentinel in the pending save payload", () => {
+      const s = new ConfigState()
+      s.handleConfigLoaded({ default_agent: "code" })
+      s.updateConfig({ default_agent: null })
+
+      expect(s.draft.default_agent).toBeNull()
+
+      s.saveConfig()
+
+      expect(s.saving).toBe(true)
+      expect(s.draft.default_agent).toBeNull()
+    })
+  })
+
+  describe("configSaved while a save is in-flight", () => {
+    it("clears the draft after a confirmed write even if merged refresh is pending", () => {
+      const s = new ConfigState()
+      s.handleConfigLoaded({ agent: { code: { prompt: "Review" } } })
+      s.updateConfig({ agent: { code: { prompt: null } } })
+      s.saveConfig()
+
+      s.handleConfigSaved()
+
+      expect(s.saving).toBe(false)
+      expect(s.dirty).toBe(false)
+      expect(Object.keys(s.draft).length).toBe(0)
+      expect(s.saved.agent?.code?.prompt).toBeUndefined()
+      expect(s.config.agent?.code?.prompt).toBeUndefined()
+    })
+  })
+
+  describe("configSaveFailed while a save is in-flight", () => {
+    it("preserves pending null-sentinel clears so the user can retry", () => {
+      const s = new ConfigState()
+      s.handleConfigLoaded({ agent: { code: { prompt: "Review", temperature: 0.7 } }, default_agent: "code" })
+      s.updateConfig({ agent: { code: { prompt: null, temperature: null } } })
+      s.updateConfig({ default_agent: null })
+      s.saveConfig()
+
+      s.handleConfigSaveFailed({ agent: { code: { prompt: "Review", temperature: 0.7 } }, default_agent: "code" })
+
+      expect(s.saving).toBe(false)
+      expect(s.dirty).toBe(true)
+      expect(s.draft.agent?.code?.prompt).toBeNull()
+      expect(s.draft.agent?.code?.temperature).toBeNull()
+      expect(s.draft.default_agent).toBeNull()
+      expect(s.config.agent?.code?.prompt).toBeUndefined()
+      expect(s.config.agent?.code?.temperature).toBeUndefined()
+      expect(s.config.default_agent).toBeUndefined()
+    })
+  })
+
+  it("ignores repeated save attempts while a save is already in-flight", () => {
+    const s = new ConfigState()
+    s.handleConfigLoaded({ snapshot: true })
+    s.updateConfig({ snapshot: false })
+
+    s.saveConfig()
+    s.saveConfig()
+    s.handleConfigUpdated({ snapshot: false })
+
+    expect(s.saving).toBe(false)
+    expect(s.dirty).toBe(false)
+    expect(s.config.snapshot).toBe(false)
   })
 
   it("configLoaded is ignored while save is in-flight", () => {

packages/kilo-vscode/webview-ui/src/components/settings/AgentBehaviourTab.tsx

@@ -15,6 +15,7 @@ import ModeEditView from "./ModeEditView"
 import ModeCreateView from "./ModeCreateView"
 import McpEditView from "./McpEditView"
 import WorkflowsTab from "./agent-behaviour/WorkflowsTab"
+import { selectedDefaultAgentValue } from "./agent-behaviour-patches"
 import { parseImport, MAX_IMPORT_SIZE } from "./mode-io"
 import type { ImportError } from "./mode-io"
 
@@ -274,7 +275,7 @@ const AgentBehaviourTab: Component = () => {
               label={(o) => o.label}
               onSelect={(o) => {
                 if (!o) return
-                const next = o.value || null
+                const next = selectedDefaultAgentValue(o.value)
                 if (next === (config().default_agent ?? null)) return
                 updateConfig({ default_agent: next })
               }}

packages/kilo-vscode/webview-ui/src/components/settings/ModeEditView.tsx

@@ -10,6 +10,11 @@ import { useSession } from "../../context/session"
 import { useLanguage } from "../../context/language"
 import type { AgentConfig, AgentInfo } from "../../types/messages"
 import SettingsRow from "./SettingsRow"
+import {
+  selectedAgentNumberOverrideValue,
+  selectedAgentTextOverrideValue,
+  shouldClearDefaultAgentWhenAgentBecomesUnavailable,
+} from "./agent-behaviour-patches"
 import { buildExport } from "./mode-io"
 
 interface Props {
@@ -42,6 +47,16 @@ const ModeEditView: Component<Props> = (props) => {
     })
   }
 
+  const updateNumberOverride = (
+    key: "temperature" | "top_p" | "steps",
+    rawValue: string,
+    parse: (value: string) => number,
+  ) => {
+    const next = selectedAgentNumberOverrideValue(rawValue, parse)
+    if (rawValue.trim() !== "" && next === undefined) return
+    update({ [key]: next } as Pick<AgentConfig, typeof key>)
+  }
+
   const exportMode = () => {
     const data = buildExport(props.name, cfg())
     const json = JSON.stringify(data, null, 2)
@@ -106,19 +121,16 @@ const ModeEditView: Component<Props> = (props) => {
         </Card>
       </Show>
 
-      {/* Description (full-width, custom modes only) */}
-      <Show when={!native()}>
-        <Card style={{ "margin-bottom": "12px" }}>
-          <div data-slot="settings-row-label-title" style={{ "margin-bottom": "8px" }}>
-            {language.t("settings.agentBehaviour.editMode.description")}
-          </div>
-          <TextField
-            value={cfg().description ?? ""}
-            placeholder={language.t("settings.agentBehaviour.createMode.description.placeholder")}
-            onChange={(val) => update({ description: val || undefined })}
-          />
-        </Card>
-      </Show>
+      <Card style={{ "margin-bottom": "12px" }}>
+        <div data-slot="settings-row-label-title" style={{ "margin-bottom": "8px" }}>
+          {language.t("settings.agentBehaviour.editMode.description")}
+        </div>
+        <TextField
+          value={cfg().description ?? ""}
+          placeholder={language.t("settings.agentBehaviour.createMode.description.placeholder")}
+          onChange={(val) => update({ description: selectedAgentTextOverrideValue(val) })}
+        />
+      </Card>
 
       {/* Prompt (full-width, auto-resizing) */}
       <Card style={{ "margin-bottom": "12px" }}>
@@ -131,7 +143,7 @@ const ModeEditView: Component<Props> = (props) => {
           value={cfg().prompt ?? ""}
           placeholder={language.t("settings.agentBehaviour.createMode.prompt.placeholder")}
           multiline
-          onChange={(val) => update({ prompt: val || undefined })}
+          onChange={(val) => update({ prompt: selectedAgentTextOverrideValue(val) })}
         />
       </Card>
 
@@ -144,7 +156,7 @@ const ModeEditView: Component<Props> = (props) => {
           <TextField
             value={cfg().model ?? ""}
             placeholder="e.g. anthropic/claude-sonnet-4-20250514"
-            onChange={(val) => update({ model: val || undefined })}
+            onChange={(val) => update({ model: selectedAgentTextOverrideValue(val) })}
           />
         </SettingsRow>
 
@@ -155,10 +167,7 @@ const ModeEditView: Component<Props> = (props) => {
           <TextField
             value={cfg().temperature?.toString() ?? ""}
             placeholder={language.t("common.default")}
-            onChange={(val) => {
-              const parsed = parseFloat(val)
-              update({ temperature: isNaN(parsed) ? undefined : parsed })
-            }}
+            onChange={(val) => updateNumberOverride("temperature", val, parseFloat)}
           />
         </SettingsRow>
 
@@ -169,10 +178,7 @@ const ModeEditView: Component<Props> = (props) => {
           <TextField
             value={cfg().top_p?.toString() ?? ""}
             placeholder={language.t("common.default")}
-            onChange={(val) => {
-              const parsed = parseFloat(val)
-              update({ top_p: isNaN(parsed) ? undefined : parsed })
-            }}
+            onChange={(val) => updateNumberOverride("top_p", val, parseFloat)}
           />
         </SettingsRow>
 
@@ -183,10 +189,7 @@ const ModeEditView: Component<Props> = (props) => {
           <TextField
             value={cfg().steps?.toString() ?? ""}
             placeholder={language.t("common.default")}
-            onChange={(val) => {
-              const parsed = parseInt(val, 10)
-              update({ steps: isNaN(parsed) ? undefined : parsed })
-            }}
+            onChange={(val) => updateNumberOverride("steps", val, (raw) => parseInt(raw, 10))}
           />
         </SettingsRow>
 
@@ -199,7 +202,7 @@ const ModeEditView: Component<Props> = (props) => {
             onChange={(val) => {
               update({ hidden: val })
               // Clear default_agent if hiding the current default
-              if (val && config().default_agent === props.name) {
+              if (shouldClearDefaultAgentWhenAgentBecomesUnavailable(val, config().default_agent, props.name)) {
                 updateConfig({ default_agent: null })
               }
             }}
@@ -219,7 +222,7 @@ const ModeEditView: Component<Props> = (props) => {
             onChange={(val) => {
               update({ disable: val })
               // Clear default_agent if disabling the current default
-              if (val && config().default_agent === props.name) {
+              if (shouldClearDefaultAgentWhenAgentBecomesUnavailable(val, config().default_agent, props.name)) {
                 updateConfig({ default_agent: null })
               }
             }}

packages/kilo-vscode/webview-ui/src/components/settings/agent-behaviour-patches.ts

@@ -0,0 +1,24 @@
+export function selectedDefaultAgentValue(value: string): string | null {
+  return value || null
+}
+
+export function selectedAgentTextOverrideValue(value: string): string | null {
+  return value === "" ? null : value
+}
+
+export function selectedAgentNumberOverrideValue(
+  value: string,
+  parse: (value: string) => number,
+): number | null | undefined {
+  if (value.trim() === "") return null
+  const parsed = parse(value)
+  return Number.isNaN(parsed) ? undefined : parsed
+}
+
+export function shouldClearDefaultAgentWhenAgentBecomesUnavailable(
+  nextValue: boolean,
+  currentDefaultAgent: string | null | undefined,
+  agentName: string,
+): boolean {
+  return nextValue && currentDefaultAgent === agentName
+}

packages/kilo-vscode/webview-ui/src/context/config.tsx

@@ -67,6 +67,22 @@ export const ConfigProvider: ParentComponent = (props) => {
       setSaved(message.config)
       return
     }
+    if (message.type === "configSaved") {
+      if (!saving) return
+      const confirmedConfig = config()
+      saving = false
+      setDraft({})
+      setIsDirty(false)
+      setSaved(confirmedConfig)
+      return
+    }
+    if (message.type === "configSaveFailed") {
+      if (!saving) return
+      saving = false
+      setSaved(message.config)
+      setConfig(resolveConfig(message.config, draft(), isDirty()))
+      return
+    }
   })
 
   onCleanup(unsubscribe)
@@ -101,7 +117,7 @@ export const ConfigProvider: ParentComponent = (props) => {
 
   function saveConfig() {
     const changes = draft()
-    if (Object.keys(changes).length === 0) return
+    if (saving || Object.keys(changes).length === 0) return
     // Don't clear draft/isDirty yet — wait for configUpdated confirmation.
     // If the write fails, the save bar stays visible so the user can retry.
     saving = true

packages/kilo-vscode/webview-ui/src/types/messages.ts

@@ -321,14 +321,14 @@ export type PermissionConfig = Partial<Record<string, PermissionRule>>
 
 export interface AgentConfig {
   model?: string | null
-  prompt?: string
-  description?: string
+  prompt?: string | null
+  description?: string | null
   mode?: "subagent" | "primary" | "all"
   hidden?: boolean
   disable?: boolean
-  temperature?: number
-  top_p?: number
-  steps?: number
+  temperature?: number | null
+  top_p?: number | null
+  steps?: number | null
   permission?: PermissionConfig
 }
 
@@ -722,6 +722,15 @@ export interface ConfigUpdatedMessage {
   config: Config
 }
 
+export interface ConfigSavedMessage {
+  type: "configSaved"
+}
+
+export interface ConfigSaveFailedMessage {
+  type: "configSaveFailed"
+  config: Config
+}
+
 export interface GlobalConfigLoadedMessage {
   type: "globalConfigLoaded"
   config: Config
@@ -1277,6 +1286,8 @@ export type ExtensionMessage =
   | BrowserSettingsLoadedMessage
   | ConfigLoadedMessage
   | ConfigUpdatedMessage
+  | ConfigSavedMessage
+  | ConfigSaveFailedMessage
   | GlobalConfigLoadedMessage
   | NotificationSettingsLoadedMessage
   | NotificationsLoadedMessage

packages/kilo-vscode/webview-ui/src/utils/config-utils.ts

@@ -81,9 +81,26 @@ export class ConfigState {
     this.saved = server
   }
 
+  /** Handle a confirmed save when merged config refresh is still pending. */
+  handleConfigSaved() {
+    if (!this.saving) return
+    this.saving = false
+    this.draft = {}
+    this.dirty = false
+    this.saved = this.config
+  }
+
+  /** Handle an explicit save failure from the extension. */
+  handleConfigSaveFailed(server: Config) {
+    if (!this.saving) return
+    this.saving = false
+    this.saved = server
+    this.config = resolveConfig(server, this.draft, this.dirty)
+  }
+
   /** Send the draft to the backend. */
   saveConfig() {
-    if (Object.keys(this.draft).length === 0) return
+    if (this.saving || Object.keys(this.draft).length === 0) return
     this.saving = true
   }
 

packages/opencode/src/config/config.ts

@@ -819,12 +819,12 @@ export namespace Config {
         .string()
         .optional()
         .describe("Default model variant for this agent (applies only when using the agent's configured model)."),
-      temperature: z.number().optional(),
-      top_p: z.number().optional(),
-      prompt: z.string().optional(),
+      temperature: z.number().nullable().optional(), // kilocode_change - nullable for delete sentinel
+      top_p: z.number().nullable().optional(), // kilocode_change - nullable for delete sentinel
+      prompt: z.string().nullable().optional(), // kilocode_change - nullable for delete sentinel
       tools: z.record(z.string(), z.boolean()).optional().describe("@deprecated Use 'permission' field instead"),
       disable: z.boolean().optional(),
-      description: z.string().optional().describe("Description of when to use the agent"),
+      description: z.string().nullable().optional().describe("Description of when to use the agent"),
       mode: z.enum(["subagent", "primary", "all"]).optional(),
       hidden: z
         .boolean()
@@ -842,6 +842,7 @@ export namespace Config {
         .number()
         .int()
         .positive()
+        .nullable()
         .optional()
         .describe("Maximum number of agentic iterations before forcing text-only response"),
       maxSteps: z.number().int().positive().optional().describe("@deprecated Use 'steps' field instead."),

packages/sdk/js/src/v2/gen/types.gen.ts

@@ -1113,9 +1113,9 @@ export type AgentConfig = {
    * Default model variant for this agent (applies only when using the agent's configured model).
    */
   variant?: string
-  temperature?: number
-  top_p?: number
-  prompt?: string
+  temperature?: number | null
+  top_p?: number | null
+  prompt?: string | null
   /**
    * @deprecated Use 'permission' field instead
    */
@@ -1126,7 +1126,7 @@ export type AgentConfig = {
   /**
    * Description of when to use the agent
    */
-  description?: string
+  description?: string | null
   mode?: "subagent" | "primary" | "all"
   /**
    * Hide this subagent from the @ autocomplete menu (default: false, only applies to mode: subagent)
@@ -1142,7 +1142,7 @@ export type AgentConfig = {
   /**
    * Maximum number of agentic iterations before forcing text-only response
    */
-  steps?: number
+  steps?: number | null
   /**
    * @deprecated Use 'steps' field instead.
    */

packages/sdk/openapi.json

@@ -12387,13 +12387,34 @@
             "type": "string"
           },
           "temperature": {
-            "type": "number"
+            "anyOf": [
+              {
+                "type": "number"
+              },
+              {
+                "type": "null"
+              }
+            ]
           },
           "top_p": {
-            "type": "number"
+            "anyOf": [
+              {
+                "type": "number"
+              },
+              {
+                "type": "null"
+              }
+            ]
           },
           "prompt": {
-            "type": "string"
+            "anyOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ]
           },
           "tools": {
             "description": "@deprecated Use 'permission' field instead",
@@ -12410,7 +12431,14 @@
           },
           "description": {
             "description": "Description of when to use the agent",
-            "type": "string"
+            "anyOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ]
           },
           "mode": {
             "type": "string",
@@ -12454,9 +12482,16 @@
           },
           "steps": {
             "description": "Maximum number of agentic iterations before forcing text-only response",
-            "type": "integer",
-            "exclusiveMinimum": 0,
-            "maximum": 9007199254740991
+            "anyOf": [
+              {
+                "type": "integer",
+                "exclusiveMinimum": 0,
+                "maximum": 9007199254740991
+              },
+              {
+                "type": "null"
+              }
+            ]
           },
           "maxSteps": {
             "description": "@deprecated Use 'steps' field instead.",