Speed up targeted opencode tests

Reduce avoidable setup costs in slow opencode tests while preserving reviewed coverage and recording the benchmark evidence for follow-up test-suite work.

packages/opencode/script/profile-test-files.ts

@@ -0,0 +1,42 @@
+// Per-file profiler for finding candidate test-speed work; see ../../perf/test-suite.md
+// for the benchmark notes, kept wins, and discarded experiments.
+// Example: TEST_PROFILE_GLOB='test/server/**/*.test.ts' TEST_PROFILE_TOP=15 bun run profile:test
+const pattern = Bun.env.TEST_PROFILE_GLOB ?? "test/**/*.test.{ts,tsx}"
+const limit = Number(Bun.env.TEST_PROFILE_LIMIT ?? 0)
+const timeout = Bun.env.TEST_PROFILE_TIMEOUT ?? "30000"
+const files = Array.fromAsync(new Bun.Glob(pattern).scan({ cwd: import.meta.dir + "/..", onlyFiles: true }))
+  .then((files) => files.toSorted())
+  .then((files) => (limit > 0 ? files.slice(0, limit) : files))
+
+const results = []
+for (const file of await files) {
+  const start = performance.now()
+  const proc = Bun.spawn(["bun", "test", "--timeout", timeout, file], {
+    cwd: import.meta.dir + "/..",
+    stdout: "pipe",
+    stderr: "pipe",
+    env: Bun.env,
+  })
+  const [output, error, exitCode] = await Promise.all([
+    new Response(proc.stdout).text(),
+    new Response(proc.stderr).text(),
+    proc.exited,
+  ])
+  const seconds = (performance.now() - start) / 1000
+  results.push({ file, seconds, exitCode })
+  console.log(`${exitCode === 0 ? "PASS" : "FAIL"} ${seconds.toFixed(3)}s ${file}`)
+  if (exitCode !== 0) console.log((output + error).trim())
+}
+
+const sorted = results.toSorted((a, b) => b.seconds - a.seconds)
+console.log("\nSlowest test files:")
+for (const result of sorted.slice(0, Number(Bun.env.TEST_PROFILE_TOP ?? 20))) {
+  console.log(`${result.seconds.toFixed(3)}s ${result.exitCode === 0 ? "PASS" : "FAIL"} ${result.file}`)
+}
+
+if (sorted[0]) {
+  console.log(`METRIC slowest_test_file_seconds=${sorted[0].seconds.toFixed(3)}`)
+  console.log(`METRIC profiled_test_files=${results.length}`)
+}
+
+if (results.some((result) => result.exitCode !== 0)) process.exit(1)