Add adapter environment testing infrastructure

Introduce testEnvironment() on ServerAdapterModule with structured
pass/warn/fail diagnostics for all four adapter types (claude_local,
codex_local, process, http). Adds POST test-environment endpoint,
shared types/validators, adapter test implementations, and UI API
client. Includes asset type foundations used by related features.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/adapters/process/index.ts

@@ -1,9 +1,11 @@
 import type { ServerAdapterModule } from "../types.js";
 import { execute } from "./execute.js";
+import { testEnvironment } from "./test.js";
 
 export const processAdapter: ServerAdapterModule = {
   type: "process",
   execute,
+  testEnvironment,
   models: [],
   agentConfigurationDoc: `# process agent configuration
 

server/src/adapters/process/test.ts

@@ -0,0 +1,89 @@
+import type {
+  AdapterEnvironmentCheck,
+  AdapterEnvironmentTestContext,
+  AdapterEnvironmentTestResult,
+} from "../types.js";
+import {
+  asString,
+  parseObject,
+  ensureAbsoluteDirectory,
+  ensureCommandResolvable,
+  ensurePathInEnv,
+} from "../utils.js";
+
+function summarizeStatus(checks: AdapterEnvironmentCheck[]): AdapterEnvironmentTestResult["status"] {
+  if (checks.some((check) => check.level === "error")) return "fail";
+  if (checks.some((check) => check.level === "warn")) return "warn";
+  return "pass";
+}
+
+export async function testEnvironment(
+  ctx: AdapterEnvironmentTestContext,
+): Promise<AdapterEnvironmentTestResult> {
+  const checks: AdapterEnvironmentCheck[] = [];
+  const config = parseObject(ctx.config);
+  const command = asString(config.command, "");
+  const cwd = asString(config.cwd, process.cwd());
+
+  if (!command) {
+    checks.push({
+      code: "process_command_missing",
+      level: "error",
+      message: "Process adapter requires a command.",
+      hint: "Set adapterConfig.command to an executable command.",
+    });
+  } else {
+    checks.push({
+      code: "process_command_present",
+      level: "info",
+      message: `Configured command: ${command}`,
+    });
+  }
+
+  try {
+    await ensureAbsoluteDirectory(cwd);
+    checks.push({
+      code: "process_cwd_valid",
+      level: "info",
+      message: `Working directory is valid: ${cwd}`,
+    });
+  } catch (err) {
+    checks.push({
+      code: "process_cwd_invalid",
+      level: "error",
+      message: err instanceof Error ? err.message : "Invalid working directory",
+      detail: cwd,
+    });
+  }
+
+  if (command) {
+    const envConfig = parseObject(config.env);
+    const env: Record<string, string> = {};
+    for (const [key, value] of Object.entries(envConfig)) {
+      if (typeof value === "string") env[key] = value;
+    }
+    const runtimeEnv = ensurePathInEnv({ ...process.env, ...env });
+    try {
+      await ensureCommandResolvable(command, cwd, runtimeEnv);
+      checks.push({
+        code: "process_command_resolvable",
+        level: "info",
+        message: `Command is executable: ${command}`,
+      });
+    } catch (err) {
+      checks.push({
+        code: "process_command_unresolvable",
+        level: "error",
+        message: err instanceof Error ? err.message : "Command is not executable",
+        detail: command,
+      });
+    }
+  }
+
+  return {
+    adapterType: ctx.adapterType,
+    status: summarizeStatus(checks),
+    checks,
+    testedAt: new Date().toISOString(),
+  };
+}