fix(watcher): check both original and realpath against cfgIgnores, add symlink test

Address review feedback on PR #27016:
- Check both pre-realpath (resolved) and post-realpath (vcsDir) against
  cfgIgnores so user configs referencing the symlink path still work.
- Add regression test for symlinked .git directory verifying HEAD change
  events propagate through the resolved real path.

Author: kagura-agent

packages/opencode/src/file/watcher.ts

@@ -135,7 +135,7 @@ export const layer = Layer.effect(
             const vcsDir = resolved
               ? yield* Effect.promise(() => realpath(resolved).catch(() => resolved))
               : undefined
-            if (vcsDir && !cfgIgnores.includes(".git") && !cfgIgnores.includes(vcsDir)) {
+            if (vcsDir && !cfgIgnores.includes(".git") && !cfgIgnores.includes(vcsDir) && (!resolved || !cfgIgnores.includes(resolved))) {
               const ignore = (yield* Effect.promise(() => readdir(vcsDir).catch(() => []))).filter(
                 (entry) => entry !== "HEAD",
               )

packages/opencode/test/file/watcher.test.ts

@@ -247,4 +247,41 @@ describeWatcher("FileWatcher", () => {
       ),
     )
   })
+
+  // Symlink support varies by platform; skip where unavailable
+  const canSymlink = process.platform !== "win32"
+  const testSymlink = canSymlink ? test : test.skip
+
+  testSymlink("publishes .git/HEAD events through a symlinked .git directory", async () => {
+    await using tmp = await tmpdir({ git: true })
+    const dir = tmp.path
+    const actualGit = path.join(dir, "..", "tmp_actual_git_" + Math.random().toString(36).slice(2))
+    // Move .git to a sibling directory and replace with a symlink
+    await fs.rename(path.join(dir, ".git"), actualGit)
+    await fs.symlink(actualGit, path.join(dir, ".git"))
+
+    try {
+      const head = path.join(dir, ".git", "HEAD")
+      const branch = `watch-${Math.random().toString(36).slice(2)}`
+      await $`git branch ${branch}`.cwd(dir).quiet()
+
+      await withWatcher(
+        dir,
+        nextUpdate(
+          dir,
+          (evt) => evt.file === path.join(actualGit, "HEAD") && evt.event !== "unlink",
+          Effect.promise(() => fs.writeFile(head, `ref: refs/heads/${branch}\n`)),
+        ).pipe(
+          Effect.tap((evt) =>
+            Effect.sync(() => {
+              expect(evt.file).toBe(path.join(actualGit, "HEAD"))
+              expect(["add", "change"]).toContain(evt.event)
+            }),
+          ),
+        ),
+      )
+    } finally {
+      await fs.rm(actualGit, { recursive: true, force: true }).catch(() => undefined)
+    }
+  })
 })