fix(config): fall back to legacy path when migration fails and use canonical basename everywhere (#3133)

Root cause: loadPluginConfig() unconditionally switched userConfigPath to the
canonical name after calling migrateLegacyConfigFile(), even when migration
failed (e.g. file lock on Windows, permission denied). This left the config
path pointing to a non-existent file, so the plugin config silently loaded
as empty defaults.

Additionally, several fallback/default paths were hardcoded to the legacy
'oh-my-opencode' basename instead of using CONFIG_BASENAME ('oh-my-openagent'),
causing CLI config commands (writeOmoConfig, detectCurrentConfig) to write to
the wrong filename.

Changes:
- plugin-config.ts: check migrateLegacyConfigFile() return value; only switch
  to canonical path if migration succeeded OR the canonical file already exists
- opencode-config-dir.ts: use CONFIG_BASENAME for omoConfig path in
  getOpenCodeConfigPaths()
- config-context.ts: getOmoConfigPath() now uses detectPluginConfigFile() to
  find whichever name variant actually exists on disk
- plugin-config.ts: default fallback paths use CONFIG_BASENAME instead of
  hardcoded legacy name
- Added test: loadPluginConfig still loads config when migration fails
  (read-only directory simulation)

src/cli/config-manager/config-context.ts

@@ -1,4 +1,4 @@
-import { getOpenCodeConfigPaths } from "../../shared"
+import { getOpenCodeConfigPaths, detectPluginConfigFile } from "../../shared"
 import type {
   OpenCodeBinaryType,
   OpenCodeConfigPaths,
@@ -42,5 +42,8 @@ export function getConfigJsonc(): string {
 }
 
 export function getOmoConfigPath(): string {
+  const configDir = getConfigContext().paths.configDir
+  const detected = detectPluginConfigFile(configDir)
+  if (detected.format !== "none") return detected.path
   return getConfigContext().paths.omoConfig
 }

src/plugin-config.test.ts

@@ -1,5 +1,5 @@
 import { afterEach, describe, expect, it, mock, spyOn } from "bun:test";
-import { existsSync, mkdtempSync, mkdirSync, readFileSync, rmSync, writeFileSync } from "node:fs"
+import { chmodSync, existsSync, mkdtempSync, mkdirSync, readFileSync, rmSync, writeFileSync } from "node:fs"
 import { tmpdir } from "node:os"
 import { join } from "node:path"
 import * as shared from "./shared"
@@ -355,6 +355,42 @@ describe("loadPluginConfig", () => {
     expect(reloadedConfig.agents?.oracle?.model).toBe("openai/gpt-5.4")
   })
 
+  it("should still load config from legacy path when migration fails", () => {
+    // given - legacy config exists but canonical path is not writable
+    const rootDir = mkdtempSync(join(tmpdir(), "omo-plugin-config-fail-"))
+    const userConfigDir = join(rootDir, "user-config")
+    const projectDir = join(rootDir, "project")
+    const projectConfigDir = join(projectDir, ".opencode")
+    const legacyConfigPath = join(projectConfigDir, "oh-my-opencode.json")
+
+    tempDirs.push(rootDir)
+    mkdirSync(userConfigDir, { recursive: true })
+    mkdirSync(projectConfigDir, { recursive: true })
+    writeFileSync(legacyConfigPath, JSON.stringify({ agents: { oracle: { model: "openai/gpt-5.4" } } }))
+
+    // Make the directory read-only so migration write fails
+    // (simulates Windows file lock / permission issues)
+    if (process.platform !== "win32") {
+      chmodSync(projectConfigDir, 0o555)
+    }
+
+    spyOn(shared, "getOpenCodeConfigDir").mockReturnValue(userConfigDir)
+
+    // when
+    let config: OhMyOpenCodeConfig
+    try {
+      config = loadPluginConfig(projectDir, {})
+    } finally {
+      // Restore permissions for cleanup
+      if (process.platform !== "win32") {
+        chmodSync(projectConfigDir, 0o755)
+      }
+    }
+
+    // then - should still load the config from legacy path
+    expect(config.agents?.oracle?.model).toBe("openai/gpt-5.4")
+  })
+
   it("should load migrated legacy project config on the first load", () => {
     // given
     const rootDir = mkdtempSync(join(tmpdir(), "omo-plugin-config-first-load-"))

src/plugin-config.ts

@@ -175,7 +175,7 @@ export function loadPluginConfig(
   let userConfigPath =
     userDetected.format !== "none"
       ? userDetected.path
-      : path.join(configDir, "oh-my-opencode.json");
+      : path.join(configDir, `${CONFIG_BASENAME}.json`);
 
   if (userDetected.legacyPath) {
     log("Canonical plugin config detected alongside legacy config. Remove the legacy file to avoid confusion.", {
@@ -186,11 +186,16 @@ export function loadPluginConfig(
 
   // Auto-copy legacy config file to canonical name if needed
   if (userDetected.format !== "none" && path.basename(userDetected.path).startsWith(LEGACY_CONFIG_BASENAME)) {
-    migrateLegacyConfigFile(userDetected.path);
-    userConfigPath = path.join(
+    const migrated = migrateLegacyConfigFile(userDetected.path);
+    const canonicalPath = path.join(
       path.dirname(userDetected.path),
       `${CONFIG_BASENAME}${path.extname(userDetected.path)}`
     );
+    // Only switch to canonical path if migration succeeded OR canonical file already exists
+    if (migrated || fs.existsSync(canonicalPath)) {
+      userConfigPath = canonicalPath;
+    }
+    // Otherwise keep loading from the legacy path that was detected
   }
 
   // Project-level config path - prefer .jsonc over .json
@@ -199,7 +204,7 @@ export function loadPluginConfig(
   let projectConfigPath =
     projectDetected.format !== "none"
       ? projectDetected.path
-      : path.join(projectBasePath, "oh-my-opencode.json");
+      : path.join(projectBasePath, `${CONFIG_BASENAME}.json`);
 
   if (projectDetected.legacyPath) {
     log("Canonical plugin config detected alongside legacy config. Remove the legacy file to avoid confusion.", {
@@ -210,11 +215,16 @@ export function loadPluginConfig(
 
   // Auto-copy legacy project config file to canonical name if needed
   if (projectDetected.format !== "none" && path.basename(projectDetected.path).startsWith(LEGACY_CONFIG_BASENAME)) {
-    migrateLegacyConfigFile(projectDetected.path);
-    projectConfigPath = path.join(
+    const projectMigrated = migrateLegacyConfigFile(projectDetected.path);
+    const canonicalProjectPath = path.join(
       path.dirname(projectDetected.path),
       `${CONFIG_BASENAME}${path.extname(projectDetected.path)}`
     );
+    // Only switch to canonical path if migration succeeded OR canonical file already exists
+    if (projectMigrated || fs.existsSync(canonicalProjectPath)) {
+      projectConfigPath = canonicalProjectPath;
+    }
+    // Otherwise keep loading from the legacy path that was detected
   }
 
   // Load user config first (base). Parse empty config through Zod to apply field defaults.

src/shared/opencode-config-dir.test.ts

@@ -289,7 +289,7 @@ describe("opencode-config-dir", () => {
       expect(paths.configJson).toBe(join(expectedDir, "opencode.json"))
       expect(paths.configJsonc).toBe(join(expectedDir, "opencode.jsonc"))
       expect(paths.packageJson).toBe(join(expectedDir, "package.json"))
-      expect(paths.omoConfig).toBe(join(expectedDir, "oh-my-opencode.json"))
+      expect(paths.omoConfig).toBe(join(expectedDir, "oh-my-openagent.json"))
     })
 
     test("returns all config paths for desktop binary", () => {
@@ -305,7 +305,7 @@ describe("opencode-config-dir", () => {
       expect(paths.configJson).toBe(join(expectedDir, "opencode.json"))
       expect(paths.configJsonc).toBe(join(expectedDir, "opencode.jsonc"))
       expect(paths.packageJson).toBe(join(expectedDir, "package.json"))
-      expect(paths.omoConfig).toBe(join(expectedDir, "oh-my-opencode.json"))
+      expect(paths.omoConfig).toBe(join(expectedDir, "oh-my-openagent.json"))
     })
   })
 

src/shared/opencode-config-dir.ts

@@ -2,6 +2,8 @@ import { existsSync, realpathSync } from "node:fs"
 import { homedir } from "node:os"
 import { join, resolve, win32 } from "node:path"
 
+import { CONFIG_BASENAME } from "./plugin-identity"
+
 import type {
   OpenCodeBinaryType,
   OpenCodeConfigDirOptions,
@@ -97,7 +99,7 @@ export function getOpenCodeConfigPaths(options: OpenCodeConfigDirOptions): OpenC
     configJson: join(configDir, "opencode.json"),
     configJsonc: join(configDir, "opencode.jsonc"),
     packageJson: join(configDir, "package.json"),
-    omoConfig: join(configDir, "oh-my-opencode.json"),
+    omoConfig: join(configDir, `${CONFIG_BASENAME}.json`),
   }
 }