diff --git a/src/cli/config-manager/add-plugin-to-opencode-config.test.ts b/src/cli/config-manager/add-plugin-to-opencode-config.test.ts
new file mode 100644
index 000000000..0b37fde16
--- /dev/null
+++ b/src/cli/config-manager/add-plugin-to-opencode-config.test.ts
@@ -0,0 +1,109 @@
+import { afterEach, beforeEach, describe, expect, it } from "bun:test"
+import { mkdirSync, readFileSync, rmSync, writeFileSync } from "node:fs"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+
+import { initConfigContext, resetConfigContext } from "./config-context"
+import { addPluginToOpenCodeConfig } from "./add-plugin-to-opencode-config"
+
+describe("addPluginToOpenCodeConfig", () => {
+  let testConfigDir = ""
+  let testConfigPath = ""
+
+  beforeEach(() => {
+    testConfigDir = join(tmpdir(), `omo-add-plugin-${Date.now()}-${Math.random().toString(36).slice(2)}`)
+    testConfigPath = join(testConfigDir, "opencode.json")
+
+    mkdirSync(testConfigDir, { recursive: true })
+    process.env.OPENCODE_CONFIG_DIR = testConfigDir
+    resetConfigContext()
+    initConfigContext("opencode", null)
+  })
+
+  afterEach(() => {
+    rmSync(testConfigDir, { recursive: true, force: true })
+    resetConfigContext()
+    delete process.env.OPENCODE_CONFIG_DIR
+  })
+
+  describe("#given opencode.json with oh-my-opencode plugin", () => {
+    it("replaces oh-my-opencode with new plugin entry", async () => {
+      // given
+      const config = { plugin: ["oh-my-opencode"] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = await addPluginToOpenCodeConfig("3.11.0")
+
+      // then
+      expect(result.success).toBe(true)
+      const savedConfig = JSON.parse(readFileSync(testConfigPath, "utf-8"))
+      // getPluginNameWithVersion returns just the name (without version) for non-dist-tag versions
+      expect(savedConfig.plugin).toContain("oh-my-openagent")
+      expect(savedConfig.plugin).not.toContain("oh-my-opencode")
+    })
+
+    it("replaces oh-my-opencode@old-version with new plugin entry", async () => {
+      // given
+      const config = { plugin: ["oh-my-opencode@1.0.0"] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = await addPluginToOpenCodeConfig("3.11.0")
+
+      // then
+      expect(result.success).toBe(true)
+      const savedConfig = JSON.parse(readFileSync(testConfigPath, "utf-8"))
+      expect(savedConfig.plugin).toContain("oh-my-openagent")
+      expect(savedConfig.plugin).not.toContain("oh-my-opencode@1.0.0")
+    })
+  })
+
+  describe("#given opencode.json with oh-my-openagent plugin", () => {
+    it("keeps existing oh-my-openagent when no version change needed", async () => {
+      // given
+      const config = { plugin: ["oh-my-openagent"] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = await addPluginToOpenCodeConfig("3.11.0")
+
+      // then
+      expect(result.success).toBe(true)
+      const savedConfig = JSON.parse(readFileSync(testConfigPath, "utf-8"))
+      // Should keep the existing entry since getPluginNameWithVersion returns same name
+      expect(savedConfig.plugin).toContain("oh-my-openagent")
+    })
+
+    it("replaces oh-my-openagent@old-version with new plugin entry", async () => {
+      // given
+      const config = { plugin: ["oh-my-openagent@1.0.0"] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = await addPluginToOpenCodeConfig("3.11.0")
+
+      // then
+      expect(result.success).toBe(true)
+      const savedConfig = JSON.parse(readFileSync(testConfigPath, "utf-8"))
+      expect(savedConfig.plugin).toContain("oh-my-openagent")
+    })
+  })
+
+  describe("#given opencode.json with other plugins", () => {
+    it("adds new plugin alongside existing plugins", async () => {
+      // given
+      const config = { plugin: ["some-other-plugin"] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = await addPluginToOpenCodeConfig("3.11.0")
+
+      // then
+      expect(result.success).toBe(true)
+      const savedConfig = JSON.parse(readFileSync(testConfigPath, "utf-8"))
+      expect(savedConfig.plugin).toContain("oh-my-openagent")
+      expect(savedConfig.plugin).toContain("some-other-plugin")
+    })
+  })
+})
diff --git a/src/cli/config-manager/add-plugin-to-opencode-config.ts b/src/cli/config-manager/add-plugin-to-opencode-config.ts
index cbe6fcc42..6d0d40ba3 100644
--- a/src/cli/config-manager/add-plugin-to-opencode-config.ts
+++ b/src/cli/config-manager/add-plugin-to-opencode-config.ts
@@ -1,6 +1,6 @@
 import { readFileSync, writeFileSync } from "node:fs"
+import { LEGACY_PLUGIN_NAME, PLUGIN_NAME } from "../../shared"
 import type { ConfigMergeResult } from "../types"
-import { PLUGIN_NAME, LEGACY_PLUGIN_NAME } from "../../shared"
 import { getConfigDir } from "./config-context"
 import { ensureConfigDirectoryExists } from "./ensure-config-directory-exists"
 import { formatErrorWithSuggestion } from "./format-error-with-suggestion"
@@ -13,11 +13,11 @@ const PACKAGE_NAME = PLUGIN_NAME
 export async function addPluginToOpenCodeConfig(currentVersion: string): Promise<ConfigMergeResult> {
   try {
     ensureConfigDirectoryExists()
-  } catch (err) {
+  } catch (error) {
     return {
       success: false,
       configPath: getConfigDir(),
-      error: formatErrorWithSuggestion(err, "create config directory"),
+      error: formatErrorWithSuggestion(error, "create config directory"),
     }
   }
 
@@ -42,7 +42,6 @@ export async function addPluginToOpenCodeConfig(currentVersion: string): Promise
 
     const config = parseResult.config
     const plugins = config.plugin ?? []
-
     const currentNameIndex = plugins.findIndex(
       (plugin) => plugin === PLUGIN_NAME || plugin.startsWith(`${PLUGIN_NAME}@`)
     )
@@ -69,7 +68,7 @@ export async function addPluginToOpenCodeConfig(currentVersion: string): Promise
       const match = content.match(pluginArrayRegex)
 
       if (match) {
-        const formattedPlugins = plugins.map((p) => `"${p}"`).join(",\n    ")
+        const formattedPlugins = plugins.map((plugin) => `"${plugin}"`).join(",\n    ")
         const newContent = content.replace(pluginArrayRegex, `"plugin": [\n    ${formattedPlugins}\n  ]`)
         writeFileSync(path, newContent)
       } else {
@@ -81,11 +80,11 @@ export async function addPluginToOpenCodeConfig(currentVersion: string): Promise
     }
 
     return { success: true, configPath: path }
-  } catch (err) {
+  } catch (error) {
     return {
       success: false,
       configPath: path,
-      error: formatErrorWithSuggestion(err, "update opencode config"),
+      error: formatErrorWithSuggestion(error, "update opencode config"),
     }
   }
 }
diff --git a/src/cli/config-manager/detect-current-config.test.ts b/src/cli/config-manager/detect-current-config.test.ts
new file mode 100644
index 000000000..304cf70c5
--- /dev/null
+++ b/src/cli/config-manager/detect-current-config.test.ts
@@ -0,0 +1,106 @@
+import { afterEach, beforeEach, describe, expect, it } from "bun:test"
+import { mkdirSync, rmSync, writeFileSync } from "node:fs"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+
+import { initConfigContext, resetConfigContext } from "./config-context"
+import { detectCurrentConfig } from "./detect-current-config"
+
+describe("detectCurrentConfig", () => {
+  let testConfigDir = ""
+  let testConfigPath = ""
+
+  beforeEach(() => {
+    testConfigDir = join(tmpdir(), `omo-detect-config-${Date.now()}-${Math.random().toString(36).slice(2)}`)
+    testConfigPath = join(testConfigDir, "opencode.json")
+
+    mkdirSync(testConfigDir, { recursive: true })
+    process.env.OPENCODE_CONFIG_DIR = testConfigDir
+    resetConfigContext()
+    initConfigContext("opencode", null)
+  })
+
+  afterEach(() => {
+    rmSync(testConfigDir, { recursive: true, force: true })
+    resetConfigContext()
+    delete process.env.OPENCODE_CONFIG_DIR
+  })
+
+  describe("#given opencode.json with oh-my-opencode plugin", () => {
+    it("returns isInstalled: true when plugin array contains oh-my-opencode", () => {
+      // given
+      const config = { plugin: ["oh-my-opencode"] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = detectCurrentConfig()
+
+      // then
+      expect(result.isInstalled).toBe(true)
+    })
+
+    it("returns isInstalled: true when plugin array contains oh-my-opencode with version", () => {
+      // given
+      const config = { plugin: ["oh-my-opencode@3.11.0"] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = detectCurrentConfig()
+
+      // then
+      expect(result.isInstalled).toBe(true)
+    })
+  })
+
+  describe("#given opencode.json with oh-my-openagent plugin", () => {
+    it("returns isInstalled: true when plugin array contains oh-my-openagent", () => {
+      // given
+      const config = { plugin: ["oh-my-openagent"] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = detectCurrentConfig()
+
+      // then
+      expect(result.isInstalled).toBe(true)
+    })
+
+    it("returns isInstalled: true when plugin array contains oh-my-openagent with version", () => {
+      // given
+      const config = { plugin: ["oh-my-openagent@3.11.0"] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = detectCurrentConfig()
+
+      // then
+      expect(result.isInstalled).toBe(true)
+    })
+  })
+
+  describe("#given opencode.json with no plugin", () => {
+    it("returns isInstalled: false when plugin array is empty", () => {
+      // given
+      const config = { plugin: [] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = detectCurrentConfig()
+
+      // then
+      expect(result.isInstalled).toBe(false)
+    })
+
+    it("returns isInstalled: false when plugin array does not contain our plugin", () => {
+      // given
+      const config = { plugin: ["some-other-plugin"] }
+      writeFileSync(testConfigPath, JSON.stringify(config, null, 2) + "\n", "utf-8")
+
+      // when
+      const result = detectCurrentConfig()
+
+      // then
+      expect(result.isInstalled).toBe(false)
+    })
+  })
+})
diff --git a/src/cli/config-manager/detect-current-config.ts b/src/cli/config-manager/detect-current-config.ts
index 3679d5bd6..aada6247f 100644
--- a/src/cli/config-manager/detect-current-config.ts
+++ b/src/cli/config-manager/detect-current-config.ts
@@ -36,12 +36,12 @@ function detectProvidersFromOmoConfig(): {
       }
     }
 
-    const configStr = JSON.stringify(omoConfig)
-    const hasOpenAI = configStr.includes('"openai/')
-    const hasOpencodeZen = configStr.includes('"opencode/')
-    const hasZaiCodingPlan = configStr.includes('"zai-coding-plan/')
-    const hasKimiForCoding = configStr.includes('"kimi-for-coding/')
-    const hasOpencodeGo = configStr.includes('"opencode-go/')
+    const configString = JSON.stringify(omoConfig)
+    const hasOpenAI = configString.includes('"openai/')
+    const hasOpencodeZen = configString.includes('"opencode/')
+    const hasZaiCodingPlan = configString.includes('"zai-coding-plan/')
+    const hasKimiForCoding = configString.includes('"kimi-for-coding/')
+    const hasOpencodeGo = configString.includes('"opencode-go/')
 
     return { hasOpenAI, hasOpencodeZen, hasZaiCodingPlan, hasKimiForCoding, hasOpencodeGo }
   } catch {
@@ -56,8 +56,12 @@ function detectProvidersFromOmoConfig(): {
 }
 
 function isOurPlugin(plugin: string): boolean {
-  return plugin === PLUGIN_NAME || plugin.startsWith(`${PLUGIN_NAME}@`) ||
-         plugin === LEGACY_PLUGIN_NAME || plugin.startsWith(`${LEGACY_PLUGIN_NAME}@`)
+  return (
+    plugin === PLUGIN_NAME ||
+    plugin.startsWith(`${PLUGIN_NAME}@`) ||
+    plugin === LEGACY_PLUGIN_NAME ||
+    plugin.startsWith(`${LEGACY_PLUGIN_NAME}@`)
+  )
 }
 
 export function detectCurrentConfig(): DetectedConfig {
diff --git a/src/plugin-config-path.ts b/src/plugin-config-path.ts
new file mode 100644
index 000000000..af03f4f44
--- /dev/null
+++ b/src/plugin-config-path.ts
@@ -0,0 +1,65 @@
+import * as fs from "fs";
+import { detectConfigFile, log } from "./shared";
+
+interface ResolveConfigPathOptions {
+  preferredBasePath: string;
+  legacyBasePath: string;
+}
+
+function getDefaultConfigPath(basePath: string): string {
+  return `${basePath}.json`;
+}
+
+function getTargetPath(preferredBasePath: string, format: "json" | "jsonc"): string {
+  return `${preferredBasePath}.${format}`;
+}
+
+function migrateLegacyConfigPath(
+  legacyPath: string,
+  preferredBasePath: string,
+  format: "json" | "jsonc"
+): string {
+  const targetPath = getTargetPath(preferredBasePath, format);
+  const timestamp = new Date().toISOString().replace(/[:.]/g, "-");
+  const backupPath = `${legacyPath}.bak.${timestamp}`;
+
+  try {
+    fs.copyFileSync(legacyPath, backupPath);
+  } catch (error) {
+    log(`Failed to create backup before config path migration: ${legacyPath}`, error);
+    return legacyPath;
+  }
+
+  try {
+    fs.renameSync(legacyPath, targetPath);
+    log(`Migrated legacy config path to new name: ${legacyPath} -> ${targetPath} (backup: ${backupPath})`);
+    return targetPath;
+  } catch (error) {
+    log(`Failed to migrate legacy config path: ${legacyPath} -> ${targetPath}`, error);
+    return legacyPath;
+  }
+}
+
+export function resolveConfigPathWithLegacyMigration({
+  preferredBasePath,
+  legacyBasePath,
+}: ResolveConfigPathOptions): string {
+  const preferredDetected = detectConfigFile(preferredBasePath);
+  const legacyDetected = detectConfigFile(legacyBasePath);
+
+  if (preferredDetected.format !== "none") {
+    if (legacyDetected.format !== "none") {
+      log(
+        `Detected legacy config also exists at ${legacyDetected.path}. Using new config path: ${preferredDetected.path}`
+      );
+    }
+    return preferredDetected.path;
+  }
+
+  if (legacyDetected.format === "none") {
+    return getDefaultConfigPath(preferredBasePath);
+  }
+
+  log(`Legacy config basename detected at ${legacyDetected.path}. Attempting auto-migration to new basename.`);
+  return migrateLegacyConfigPath(legacyDetected.path, preferredBasePath, legacyDetected.format);
+}
diff --git a/src/plugin-config.test.ts b/src/plugin-config.test.ts
index 3d6c82030..0cf77da08 100644
--- a/src/plugin-config.test.ts
+++ b/src/plugin-config.test.ts
@@ -1,6 +1,18 @@
-import { describe, expect, it } from "bun:test";
-import { mergeConfigs, parseConfigPartially } from "./plugin-config";
+import { afterEach, beforeEach, describe, expect, it, spyOn } from "bun:test";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import {
+  loadPluginConfig,
+  mergeConfigs,
+  parseConfigPartially,
+} from "./plugin-config";
 import type { OhMyOpenAgentConfig } from "./config";
+import {
+  CONFIG_BASENAME,
+  LEGACY_CONFIG_BASENAME,
+} from "./shared/plugin-identity";
+import { getLogFilePath } from "./shared";
 
 describe("mergeConfigs", () => {
   describe("categories merging", () => {
@@ -237,3 +249,145 @@ describe("parseConfigPartially", () => {
     });
   });
 });
+
+describe("loadPluginConfig", () => {
+  let tempDirectory: string;
+  let opencodeConfigDirectory: string;
+  let projectOpencodeDirectory: string;
+  let originalOpencodeConfigDirectory: string | undefined;
+
+  beforeEach(() => {
+    tempDirectory = fs.mkdtempSync(path.join(os.tmpdir(), "omo-config-test-"));
+    opencodeConfigDirectory = path.join(tempDirectory, "user-config");
+    projectOpencodeDirectory = path.join(tempDirectory, ".opencode");
+    fs.mkdirSync(opencodeConfigDirectory, { recursive: true });
+    fs.mkdirSync(projectOpencodeDirectory, { recursive: true });
+
+    originalOpencodeConfigDirectory = process.env.OPENCODE_CONFIG_DIR;
+    process.env.OPENCODE_CONFIG_DIR = opencodeConfigDirectory;
+
+    fs.writeFileSync(getLogFilePath(), "", "utf-8");
+  });
+
+  afterEach(() => {
+    if (originalOpencodeConfigDirectory === undefined) {
+      delete process.env.OPENCODE_CONFIG_DIR;
+    } else {
+      process.env.OPENCODE_CONFIG_DIR = originalOpencodeConfigDirectory;
+    }
+
+    fs.rmSync(tempDirectory, { recursive: true, force: true });
+  });
+
+  describe("#given new config file exists", () => {
+    describe("#when loading config", () => {
+      it("#then finds oh-my-openagent.jsonc", () => {
+        const newConfigPath = path.join(
+          opencodeConfigDirectory,
+          `${CONFIG_BASENAME}.jsonc`
+        );
+        fs.writeFileSync(newConfigPath, '{"disabled_hooks":["comment-checker"]}\n', "utf-8");
+
+        const config = loadPluginConfig(tempDirectory, {});
+
+        expect(config.disabled_hooks).toEqual(["comment-checker"]);
+      });
+    });
+  });
+
+  describe("#given only legacy config file exists", () => {
+    describe("#when loading config", () => {
+      it("#then falls back to oh-my-opencode.jsonc", () => {
+        const legacyConfigPath = path.join(
+          opencodeConfigDirectory,
+          `${LEGACY_CONFIG_BASENAME}.jsonc`
+        );
+        fs.writeFileSync(legacyConfigPath, '{"disabled_hooks":["think-mode"]}\n', "utf-8");
+
+        const config = loadPluginConfig(tempDirectory, {});
+
+        expect(config.disabled_hooks).toEqual(["think-mode"]);
+      });
+
+      it("#then auto-renames oh-my-opencode.jsonc to oh-my-openagent.jsonc with backup", () => {
+        const legacyConfigPath = path.join(
+          opencodeConfigDirectory,
+          `${LEGACY_CONFIG_BASENAME}.jsonc`
+        );
+        const legacyContent = '{"disabled_hooks":["session-recovery"]}\n';
+        fs.writeFileSync(legacyConfigPath, legacyContent, "utf-8");
+
+        const config = loadPluginConfig(tempDirectory, {});
+
+        const newConfigPath = path.join(
+          opencodeConfigDirectory,
+          `${CONFIG_BASENAME}.jsonc`
+        );
+        expect(config.disabled_hooks).toEqual(["session-recovery"]);
+        expect(fs.existsSync(newConfigPath)).toBe(true);
+        expect(fs.existsSync(legacyConfigPath)).toBe(false);
+        expect(fs.readFileSync(newConfigPath, "utf-8")).toBe(legacyContent);
+
+        const backupFiles = fs
+          .readdirSync(opencodeConfigDirectory)
+          .filter((fileName) => fileName.startsWith(`${LEGACY_CONFIG_BASENAME}.jsonc.bak.`));
+        expect(backupFiles.length).toBe(1);
+        expect(
+          fs.readFileSync(path.join(opencodeConfigDirectory, backupFiles[0]!), "utf-8")
+        ).toBe(legacyContent);
+      });
+    });
+  });
+
+  describe("#given both new and legacy config files exist", () => {
+    describe("#when loading config", () => {
+      it("#then new name wins and logs warning about old file", () => {
+        const newConfigPath = path.join(
+          opencodeConfigDirectory,
+          `${CONFIG_BASENAME}.jsonc`
+        );
+        const legacyConfigPath = path.join(
+          opencodeConfigDirectory,
+          `${LEGACY_CONFIG_BASENAME}.jsonc`
+        );
+        fs.writeFileSync(newConfigPath, '{"disabled_hooks":["comment-checker"]}\n', "utf-8");
+        fs.writeFileSync(legacyConfigPath, '{"disabled_hooks":["think-mode"]}\n', "utf-8");
+
+        const config = loadPluginConfig(tempDirectory, {});
+
+        expect(config.disabled_hooks).toEqual(["comment-checker"]);
+        const logs = fs.readFileSync(getLogFilePath(), "utf-8");
+        expect(logs).toContain("legacy config also exists");
+      });
+    });
+  });
+
+  describe("#given legacy rename fails", () => {
+    describe("#when loading config", () => {
+      it("#then logs warning and continues loading legacy config", () => {
+        const legacyConfigPath = path.join(
+          opencodeConfigDirectory,
+          `${LEGACY_CONFIG_BASENAME}.jsonc`
+        );
+        fs.writeFileSync(legacyConfigPath, '{"disabled_hooks":["hashline-read-enhancer"]}\n', "utf-8");
+        fs.chmodSync(legacyConfigPath, 0o444);
+
+        const renameError = new Error("EACCES: permission denied");
+        const renameSpy = spyOn(fs, "renameSync").mockImplementation(() => {
+          throw renameError;
+        });
+
+        try {
+          const config = loadPluginConfig(tempDirectory, {});
+
+          expect(config.disabled_hooks).toEqual(["hashline-read-enhancer"]);
+          const logs = fs.readFileSync(getLogFilePath(), "utf-8");
+          expect(logs).toContain("Failed to migrate legacy config path");
+        } finally {
+          renameSpy.mockRestore();
+          fs.chmodSync(legacyConfigPath, 0o644);
+        }
+      });
+    });
+  });
+});
diff --git a/src/plugin-config.ts b/src/plugin-config.ts
index a1154b853..a9fb06708 100644
--- a/src/plugin-config.ts
+++ b/src/plugin-config.ts
@@ -1,14 +1,14 @@
-import { CONFIG_BASENAME } from "./shared/plugin-identity"
+import { CONFIG_BASENAME, LEGACY_CONFIG_BASENAME } from "./shared/plugin-identity"
 import * as fs from "fs";
 import * as path from "path";
 import { OhMyOpenAgentConfigSchema, type OhMyOpenAgentConfig } from "./config";
+import { resolveConfigPathWithLegacyMigration } from "./plugin-config-path";
 import {
   log,
   deepMerge,
   getOpenCodeConfigDir,
   addConfigLoadError,
   parseJsonc,
-  detectConfigFile,
   migrateConfigFile,
 } from "./shared";
 
@@ -161,22 +161,16 @@ export function loadPluginConfig(
   directory: string,
   ctx: unknown
 ): OhMyOpenAgentConfig {
-  // User-level config path - prefer .jsonc over .json
   const configDir = getOpenCodeConfigDir({ binary: "opencode" });
-  const userBasePath = path.join(configDir, CONFIG_BASENAME);
-  const userDetected = detectConfigFile(userBasePath);
-  const userConfigPath =
-    userDetected.format !== "none"
-      ? userDetected.path
-      : userBasePath + ".json";
+  const userConfigPath = resolveConfigPathWithLegacyMigration({
+    preferredBasePath: path.join(configDir, CONFIG_BASENAME),
+    legacyBasePath: path.join(configDir, LEGACY_CONFIG_BASENAME),
+  });
 
-  // Project-level config path - prefer .jsonc over .json
-  const projectBasePath = path.join(directory, ".opencode", CONFIG_BASENAME);
-  const projectDetected = detectConfigFile(projectBasePath);
-  const projectConfigPath =
-    projectDetected.format !== "none"
-      ? projectDetected.path
-      : projectBasePath + ".json";
+  const projectConfigPath = resolveConfigPathWithLegacyMigration({
+    preferredBasePath: path.join(directory, ".opencode", CONFIG_BASENAME),
+    legacyBasePath: path.join(directory, ".opencode", LEGACY_CONFIG_BASENAME),
+  });
 
   // Load user config first (base)
   let config: OhMyOpenAgentConfig =