Add sandbox environment support (#4415)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies.
> - The environment/runtime layer decides where agent work executes and
how the control plane reaches those runtimes.
> - Today Paperclip can run locally and over SSH, but sandboxed
execution needs a first-class environment model instead of one-off
adapter behavior.
> - We also want sandbox providers to be pluggable so the core does not
hardcode every provider implementation.
> - This branch adds the Sandbox environment path, the provider
contract, and a deterministic fake provider plugin.
> - That required synchronized changes across shared contracts, plugin
SDK surfaces, server runtime orchestration, and the UI
environment/workspace flows.
> - The result is that sandbox execution becomes a core control-plane
capability while keeping provider implementations extensible and
testable.

## What Changed

- Added sandbox runtime support to the environment execution path,
including runtime URL discovery, sandbox execution targeting,
orchestration, and heartbeat integration.
- Added plugin-provider support for sandbox environments so providers
can be supplied via plugins instead of hardcoded server logic.
- Added the fake sandbox provider plugin with deterministic behavior
suitable for local and automated testing.
- Updated shared types, validators, plugin protocol definitions, and SDK
helpers to carry sandbox provider and workspace-runtime contracts across
package boundaries.
- Updated server routes and services so companies can create sandbox
environments, select them for work, and execute work through the sandbox
runtime path.
- Updated the UI environment and workspace surfaces to expose sandbox
environment configuration and selection.
- Added test coverage for sandbox runtime behavior, provider seams,
environment route guards, orchestration, and the fake provider plugin.

## Verification

- Ran locally before the final fixture-only scrub:
  - `pnpm -r typecheck`
  - `pnpm test:run`
  - `pnpm build`
- Ran locally after the final scrub amend:
  - `pnpm vitest run server/src/__tests__/runtime-api.test.ts`
- Reviewer spot checks:
  - create a sandbox environment backed by the fake provider plugin
  - run work through that environment
- confirm sandbox provider execution does not inherit host secrets
implicitly

## Risks

- This touches shared contracts, plugin SDK plumbing, server runtime
orchestration, and UI environment/workspace flows, so regressions would
likely show up as cross-layer mismatches rather than isolated type
errors.
- Runtime URL discovery and sandbox callback selection are sensitive to
host/bind configuration; if that logic is wrong, sandbox-backed
callbacks may fail even when execution succeeds.
- The fake provider plugin is intentionally deterministic and
test-oriented; future providers may expose capability gaps that this
branch does not yet cover.

## Model Used

- OpenAI Codex coding agent on a GPT-5-class backend in the
Paperclip/Codex harness. Exact backend model ID is not exposed
in-session. Tool-assisted workflow with shell execution, file editing,
git history inspection, and local test execution.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [ ] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

packages/adapter-utils/src/command-managed-runtime.ts

@@ -0,0 +1,152 @@
+import path from "node:path";
+import {
+  prepareSandboxManagedRuntime,
+  type PreparedSandboxManagedRuntime,
+  type SandboxManagedRuntimeAsset,
+  type SandboxManagedRuntimeClient,
+  type SandboxRemoteExecutionSpec,
+} from "./sandbox-managed-runtime.js";
+import type { RunProcessResult } from "./server-utils.js";
+
+export interface CommandManagedRuntimeRunner {
+  execute(input: {
+    command: string;
+    args?: string[];
+    cwd?: string;
+    env?: Record<string, string>;
+    stdin?: string;
+    timeoutMs?: number;
+    onLog?: (stream: "stdout" | "stderr", chunk: string) => Promise<void>;
+    onSpawn?: (meta: { pid: number; startedAt: string }) => Promise<void>;
+  }): Promise<RunProcessResult>;
+}
+
+export interface CommandManagedRuntimeSpec {
+  providerKey?: string | null;
+  leaseId?: string | null;
+  remoteCwd: string;
+  timeoutMs?: number | null;
+  paperclipApiUrl?: string | null;
+}
+
+export type CommandManagedRuntimeAsset = SandboxManagedRuntimeAsset;
+
+function shellQuote(value: string) {
+  return `'${value.replace(/'/g, `'"'"'`)}'`;
+}
+
+function toBuffer(bytes: Buffer | Uint8Array | ArrayBuffer): Buffer {
+  if (Buffer.isBuffer(bytes)) return bytes;
+  if (bytes instanceof ArrayBuffer) return Buffer.from(bytes);
+  return Buffer.from(bytes.buffer, bytes.byteOffset, bytes.byteLength);
+}
+
+function requireSuccessfulResult(result: RunProcessResult, action: string): void {
+  if (result.exitCode === 0 && !result.timedOut) return;
+  const stderr = result.stderr.trim();
+  const detail = stderr.length > 0 ? `: ${stderr}` : "";
+  throw new Error(`${action} failed with exit code ${result.exitCode ?? "null"}${detail}`);
+}
+
+function createCommandManagedRuntimeClient(input: {
+  runner: CommandManagedRuntimeRunner;
+  remoteCwd: string;
+  timeoutMs: number;
+}): SandboxManagedRuntimeClient {
+  const runShell = async (script: string, opts: { stdin?: string; timeoutMs?: number } = {}) => {
+    const result = await input.runner.execute({
+      command: "sh",
+      args: ["-lc", script],
+      cwd: input.remoteCwd,
+      stdin: opts.stdin,
+      timeoutMs: opts.timeoutMs ?? input.timeoutMs,
+    });
+    requireSuccessfulResult(result, script);
+    return result;
+  };
+
+  return {
+    makeDir: async (remotePath) => {
+      await runShell(`mkdir -p ${shellQuote(remotePath)}`);
+    },
+    writeFile: async (remotePath, bytes) => {
+      const body = toBuffer(bytes).toString("base64");
+      await runShell(
+        `mkdir -p ${shellQuote(path.posix.dirname(remotePath))} && base64 -d > ${shellQuote(remotePath)}`,
+        { stdin: body },
+      );
+    },
+    readFile: async (remotePath) => {
+      const result = await runShell(`base64 < ${shellQuote(remotePath)}`);
+      return Buffer.from(result.stdout.replace(/\s+/g, ""), "base64");
+    },
+    remove: async (remotePath) => {
+      const result = await input.runner.execute({
+        command: "sh",
+        args: ["-lc", `rm -rf ${shellQuote(remotePath)}`],
+        cwd: input.remoteCwd,
+        timeoutMs: input.timeoutMs,
+      });
+      requireSuccessfulResult(result, `remove ${remotePath}`);
+    },
+    run: async (command, options) => {
+      const result = await input.runner.execute({
+        command: "sh",
+        args: ["-lc", command],
+        cwd: input.remoteCwd,
+        timeoutMs: options.timeoutMs,
+      });
+      requireSuccessfulResult(result, command);
+    },
+  };
+}
+
+export async function prepareCommandManagedRuntime(input: {
+  runner: CommandManagedRuntimeRunner;
+  spec: CommandManagedRuntimeSpec;
+  adapterKey: string;
+  workspaceLocalDir: string;
+  workspaceRemoteDir?: string;
+  workspaceExclude?: string[];
+  preserveAbsentOnRestore?: string[];
+  assets?: CommandManagedRuntimeAsset[];
+  installCommand?: string | null;
+}): Promise<PreparedSandboxManagedRuntime> {
+  const timeoutMs = input.spec.timeoutMs && input.spec.timeoutMs > 0 ? input.spec.timeoutMs : 300_000;
+  const workspaceRemoteDir = input.workspaceRemoteDir ?? input.spec.remoteCwd;
+  const runtimeSpec: SandboxRemoteExecutionSpec = {
+    transport: "sandbox",
+    provider: input.spec.providerKey ?? "sandbox",
+    sandboxId: input.spec.leaseId ?? "managed",
+    remoteCwd: workspaceRemoteDir,
+    timeoutMs,
+    apiKey: null,
+    paperclipApiUrl: input.spec.paperclipApiUrl ?? null,
+  };
+  const client = createCommandManagedRuntimeClient({
+    runner: input.runner,
+    remoteCwd: workspaceRemoteDir,
+    timeoutMs,
+  });
+
+  if (input.installCommand?.trim()) {
+    const result = await input.runner.execute({
+      command: "sh",
+      args: ["-lc", input.installCommand.trim()],
+      cwd: workspaceRemoteDir,
+      timeoutMs,
+    });
+    requireSuccessfulResult(result, input.installCommand.trim());
+  }
+
+  return await prepareSandboxManagedRuntime({
+    spec: runtimeSpec,
+    client,
+    adapterKey: input.adapterKey,
+    workspaceLocalDir: input.workspaceLocalDir,
+    workspaceRemoteDir,
+    workspaceExclude: input.workspaceExclude,
+    preserveAbsentOnRestore: input.preserveAbsentOnRestore,
+    assets: input.assets,
+  });
+}