fix(auto-update): treat only explicit semver pins as user-pinned

Fixes #1920

Installer-written exact versions (e.g., oh-my-opencode@3.5.2) were incorrectly treated as user-pinned, blocking auto-updates for all installer users.

Fix isPinned to only block auto-update when pinnedVersion is an explicit semver string (user's intent). Channel tags (latest, beta, next) and bare package name all allow auto-update.

Fix installer fallback to return bare PACKAGE_NAME for stable versions and PACKAGE_NAME@{channel} for prerelease versions, preserving channel tracking.

src/cli/config-manager.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, test, mock, beforeEach, afterEach } from "bun:test"
+import { describe, expect, test, mock, afterEach } from "bun:test"
 
 import { ANTIGRAVITY_PROVIDER_CONFIG, getPluginNameWithVersion, fetchNpmDistTags, generateOmoConfig } from "./config-manager"
 import type { InstallConfig } from "./types"
@@ -58,7 +58,7 @@ describe("getPluginNameWithVersion", () => {
     expect(result).toBe("oh-my-opencode@next")
   })
 
-  test("returns pinned version when no tag matches", async () => {
+  test("returns prerelease channel tag when no dist-tag matches prerelease version", async () => {
     // #given npm dist-tags with beta=3.0.0-beta.3
     globalThis.fetch = mock(() =>
       Promise.resolve({
@@ -70,22 +70,22 @@ describe("getPluginNameWithVersion", () => {
     // #when current version is old beta 3.0.0-beta.2
     const result = await getPluginNameWithVersion("3.0.0-beta.2")
 
-    // #then should pin to specific version
-    expect(result).toBe("oh-my-opencode@3.0.0-beta.2")
+    // #then should preserve prerelease channel
+    expect(result).toBe("oh-my-opencode@beta")
   })
 
-  test("returns pinned version when fetch fails", async () => {
+  test("returns prerelease channel tag when fetch fails", async () => {
     // #given network failure
     globalThis.fetch = mock(() => Promise.reject(new Error("Network error"))) as unknown as typeof fetch
 
     // #when current version is 3.0.0-beta.3
     const result = await getPluginNameWithVersion("3.0.0-beta.3")
 
-    // #then should fall back to pinned version
-    expect(result).toBe("oh-my-opencode@3.0.0-beta.3")
+    // #then should preserve prerelease channel
+    expect(result).toBe("oh-my-opencode@beta")
   })
 
-  test("returns pinned version when npm returns non-ok response", async () => {
+  test("returns bare package name when npm returns non-ok response for stable version", async () => {
     // #given npm returns 404
     globalThis.fetch = mock(() =>
       Promise.resolve({
@@ -97,8 +97,8 @@ describe("getPluginNameWithVersion", () => {
     // #when current version is 2.14.0
     const result = await getPluginNameWithVersion("2.14.0")
 
-    // #then should fall back to pinned version
-    expect(result).toBe("oh-my-opencode@2.14.0")
+    // #then should fall back to bare package entry
+    expect(result).toBe("oh-my-opencode")
   })
 
   test("prioritizes latest over other tags when version matches multiple", async () => {

src/cli/config-manager/plugin-name-with-version.ts

@@ -3,6 +3,15 @@ import { fetchNpmDistTags } from "./npm-dist-tags"
 const PACKAGE_NAME = "oh-my-opencode"
 const PRIORITIZED_TAGS = ["latest", "beta", "next"] as const
 
+function getFallbackEntry(version: string): string {
+  const prereleaseMatch = version.match(/-([a-zA-Z][a-zA-Z0-9]*)\./)
+  if (prereleaseMatch) {
+    return `${PACKAGE_NAME}@${prereleaseMatch[1]}`
+  }
+
+  return PACKAGE_NAME
+}
+
 export async function getPluginNameWithVersion(currentVersion: string): Promise<string> {
   const distTags = await fetchNpmDistTags(PACKAGE_NAME)
 
@@ -15,5 +24,5 @@ export async function getPluginNameWithVersion(currentVersion: string): Promise<
     }
   }
 
-  return `${PACKAGE_NAME}@${currentVersion}`
+  return getFallbackEntry(currentVersion)
 }