feat: apply currentMode preset on startup when config drift detected

package.json

@@ -1,6 +1,6 @@
 {
   "name": "opencode-agent-modes",
-  "version": "0.1.2",
+  "version": "0.2.0",
   "description": "OpenCode plugin to switch agent modes between performance and economy presets",
   "module": "src/index.ts",
   "main": "dist/index.js",

src/modes/manager.test.ts

@@ -1,12 +1,22 @@
 import { beforeEach, describe, expect, test } from 'bun:test'
 import type { OpencodeClient } from '@opencode-ai/sdk'
 import type {
+  ModePreset,
   ModeSwitcherConfig,
   OhMyOpencodeConfig,
   OpencodeConfig,
 } from '../config/types.ts'
 import { createMockOpencodeClient, sampleConfigs } from '../test-utils/mocks.ts'
 
+/**
+ * Creates a deep copy of the sample plugin config for isolated test use.
+ */
+function clonePluginConfig(): ModeSwitcherConfig {
+  return JSON.parse(
+    JSON.stringify(sampleConfigs.pluginConfig)
+  ) as ModeSwitcherConfig
+}
+
 /**
  * Mock implementation of ModeManager for testing purposes.
  *
@@ -23,6 +33,9 @@ class MockModeManager {
   private ohMyConfig: OhMyOpencodeConfig | null = null
   private client: OpencodeClient
 
+  /** Tracks whether a drift-toast was shown during initialize */
+  lastDriftToast: string | null = null
+
   constructor(client: OpencodeClient) {
     this.client = client
   }
@@ -41,11 +54,79 @@ class MockModeManager {
 
   async initialize(): Promise<void> {
     if (!this.config) {
-      // Deep copy to avoid state sharing between tests
-      this.config = JSON.parse(
-        JSON.stringify(sampleConfigs.pluginConfig)
-      ) as ModeSwitcherConfig
+      this.config = clonePluginConfig()
+    }
+    await this.applyCurrentModeIfNeeded()
+  }
+
+  private async applyCurrentModeIfNeeded(): Promise<void> {
+    if (!this.config) {
+      return
+    }
+
+    const preset = this.config.presets[this.config.currentMode]
+    if (!preset) {
+      return
     }
+
+    const drifted = this.hasConfigDrift(preset)
+    if (!drifted) {
+      return
+    }
+
+    // Apply preset to in-memory configs
+    if (this.opencodeConfig) {
+      if (preset.model) {
+        this.opencodeConfig.model = preset.model
+      }
+      this.opencodeConfig.agent = this.opencodeConfig.agent || {}
+      for (const [name, p] of Object.entries(preset.opencode)) {
+        this.opencodeConfig.agent[name] = {
+          ...this.opencodeConfig.agent[name],
+          model: p.model,
+        }
+      }
+    }
+
+    if (this.ohMyConfig) {
+      this.ohMyConfig.agents = this.ohMyConfig.agents || {}
+      for (const [name, p] of Object.entries(preset['oh-my-opencode'])) {
+        this.ohMyConfig.agents[name] = { model: p.model }
+      }
+    }
+
+    this.lastDriftToast = `Applied "${this.config.currentMode}" mode. Restart opencode to take effect.`
+  }
+
+  private hasConfigDrift(preset: ModePreset): boolean {
+    // Check global model
+    if (preset.model && this.opencodeConfig) {
+      if (this.opencodeConfig.model !== preset.model) {
+        return true
+      }
+    }
+
+    // Check opencode agent models
+    if (this.opencodeConfig?.agent) {
+      for (const [name, p] of Object.entries(preset.opencode)) {
+        const actual = this.opencodeConfig.agent[name]
+        if (actual?.model !== p.model) {
+          return true
+        }
+      }
+    }
+
+    // Check oh-my-opencode agent models
+    if (this.ohMyConfig?.agents) {
+      for (const [name, p] of Object.entries(preset['oh-my-opencode'])) {
+        const actual = this.ohMyConfig.agents[name]
+        if (actual?.model !== p.model) {
+          return true
+        }
+      }
+    }
+
+    return false
   }
 
   private async ensureConfig(): Promise<ModeSwitcherConfig> {
@@ -384,4 +465,114 @@ describe('ModeManager', () => {
       expect(result).toBe(false)
     })
   })
+
+  describe('applyCurrentModeIfNeeded', () => {
+    test('applies preset when opencode.json has drifted', async () => {
+      // Set currentMode to economy but opencode.json has performance models
+      const config = clonePluginConfig()
+      config.currentMode = 'economy'
+      manager.setConfig(config)
+      manager.setOpencodeConfig({
+        model: 'anthropic/claude-sonnet-4',
+        agent: {
+          build: { model: 'anthropic/claude-sonnet-4' },
+          plan: { model: 'anthropic/claude-sonnet-4' },
+        },
+      })
+
+      await manager.initialize()
+
+      expect(manager.lastDriftToast).toContain('economy')
+      expect(manager.lastDriftToast).toContain('Restart opencode')
+    })
+
+    test('applies preset when oh-my-opencode.json has drifted', async () => {
+      const config = clonePluginConfig()
+      config.currentMode = 'economy'
+      manager.setConfig(config)
+      manager.setOhMyConfig({
+        agents: {
+          coder: { model: 'anthropic/claude-sonnet-4' },
+        },
+      })
+
+      await manager.initialize()
+
+      expect(manager.lastDriftToast).toContain('economy')
+    })
+
+    test('does not apply when configs match preset', async () => {
+      // Set currentMode to economy and configs already match
+      const config = clonePluginConfig()
+      config.currentMode = 'economy'
+      manager.setConfig(config)
+      manager.setOpencodeConfig({
+        model: 'opencode/glm-4.7-free',
+        agent: {
+          build: { model: 'opencode/glm-4.7-free' },
+          plan: { model: 'opencode/glm-4.7-free' },
+        },
+      })
+      manager.setOhMyConfig({
+        agents: {
+          coder: { model: 'opencode/glm-4.7-free' },
+        },
+      })
+
+      await manager.initialize()
+
+      expect(manager.lastDriftToast).toBeNull()
+    })
+
+    test('does nothing when preset is not found', async () => {
+      const config: ModeSwitcherConfig = {
+        currentMode: 'nonexistent',
+        showToastOnStartup: true,
+        presets: {
+          performance: {
+            description: 'Test',
+            opencode: {},
+            'oh-my-opencode': {},
+          },
+        },
+      }
+      manager.setConfig(config)
+      manager.setOpencodeConfig({
+        model: 'anthropic/claude-sonnet-4',
+        agent: { build: { model: 'anthropic/claude-sonnet-4' } },
+      })
+
+      await manager.initialize()
+
+      expect(manager.lastDriftToast).toBeNull()
+    })
+
+    test('does nothing when no config files exist', async () => {
+      const config = clonePluginConfig()
+      config.currentMode = 'economy'
+      manager.setConfig(config)
+      // Don't set opencodeConfig or ohMyConfig
+
+      await manager.initialize()
+
+      expect(manager.lastDriftToast).toBeNull()
+    })
+
+    test('detects drift on global model mismatch', async () => {
+      const config = clonePluginConfig()
+      config.currentMode = 'economy'
+      manager.setConfig(config)
+      manager.setOpencodeConfig({
+        model: 'anthropic/claude-sonnet-4', // Mismatch
+        agent: {
+          build: { model: 'opencode/glm-4.7-free' },
+          plan: { model: 'opencode/glm-4.7-free' },
+        },
+      })
+
+      await manager.initialize()
+
+      expect(manager.lastDriftToast).not.toBeNull()
+    })
+  })
 })

src/modes/manager.ts

@@ -59,6 +59,7 @@ export class ModeManager {
    */
   async initialize(): Promise<void> {
     this.config = await initializeConfig()
+    await this.applyCurrentModeIfNeeded()
   }
 
   /**
@@ -78,6 +79,104 @@ export class ModeManager {
     return this.config
   }
 
+  /**
+   * Checks if actual config files have drifted from the current
+   * mode preset and applies the preset if needed.
+   *
+   * This handles the case where a user manually edits
+   * `agent-mode-switcher.json` to change `currentMode` while
+   * OpenCode is not running. On next startup, the actual config
+   * files are updated to match the expected preset values,
+   * and a toast notification prompts the user to restart.
+   *
+   * @private
+   */
+  private async applyCurrentModeIfNeeded(): Promise<void> {
+    if (!this.config) {
+      return
+    }
+
+    const preset = this.config.presets[this.config.currentMode]
+    if (!preset) {
+      return
+    }
+
+    const drifted = await this.hasConfigDrift(preset)
+    if (!drifted) {
+      return
+    }
+
+    // Apply the preset to actual config files
+    await this.updateOpencodeConfig(preset.model, preset.opencode)
+    await this.updateOhMyOpencodeConfig(preset['oh-my-opencode'])
+
+    // Notify user to restart (fire-and-forget to avoid blocking
+    // plugin initialization when UI is not yet ready).
+    // TODO: Currently toast is likely not displayed because UI is
+    // not initialized at this point. To reliably show the toast,
+    // use setTimeout for delayed execution or an onReady lifecycle
+    // hook if OpenCode adds one in the future.
+    this.client.tui
+      .showToast({
+        body: {
+          title: 'Mode Applied',
+          message: `Applied "${this.config.currentMode}" mode. Restart opencode to take effect.`,
+          variant: 'warning',
+          duration: 5000,
+        },
+      })
+      .catch(() => {
+        // Toast might not be available during early initialization
+      })
+  }
+
+  /**
+   * Compares a mode preset against the actual opencode.json and
+   * oh-my-opencode.json files to detect configuration drift.
+   *
+   * Checks global model and per-agent model values. Returns true
+   * if any expected value differs from the actual file content.
+   *
+   * @param preset - The mode preset to compare against
+   * @returns True if actual configs differ from the preset
+   * @private
+   */
+  private async hasConfigDrift(preset: ModePreset): Promise<boolean> {
+    const opencodeConfig = await loadOpencodeConfig()
+    const ohMyConfig = await loadOhMyOpencodeConfig()
+
+    // Check global model in opencode.json
+    if (preset.model && opencodeConfig) {
+      if (opencodeConfig.model !== preset.model) {
+        return true
+      }
+    }
+
+    // Check opencode agent models
+    if (opencodeConfig?.agent) {
+      for (const [agentName, agentPreset] of Object.entries(preset.opencode)) {
+        const actual = opencodeConfig.agent[agentName]
+        if (actual?.model !== agentPreset.model) {
+          return true
+        }
+      }
+    }
+
+    // Check oh-my-opencode agent models
+    if (ohMyConfig?.agents) {
+      for (const [agentName, agentPreset] of Object.entries(
+        preset['oh-my-opencode']
+      )) {
+        const actual = ohMyConfig.agents[agentName]
+        if (actual?.model !== agentPreset.model) {
+          return true
+        }
+      }
+    }
+
+    return false
+  }
+
   /**
    * Gets the name of the currently active mode.
    *
@@ -316,13 +415,11 @@ export class ModeManager {
       }
 
       // Update agent section (preserve other settings)
-      if (Object.keys(agentPresets).length > 0) {
-        opencodeConfig.agent = opencodeConfig.agent || {}
-        for (const [agentName, preset] of Object.entries(agentPresets)) {
-          opencodeConfig.agent[agentName] = {
-            ...opencodeConfig.agent[agentName],
-            model: preset.model,
-          }
+      opencodeConfig.agent = opencodeConfig.agent || {}
+      for (const [agentName, preset] of Object.entries(agentPresets)) {
+        opencodeConfig.agent[agentName] = {
+          ...opencodeConfig.agent[agentName],
+          model: preset.model,
         }
       }