Add SSH environment support (#4358)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies
> - The environments subsystem already models execution environments,
but before this branch there was no end-to-end SSH-backed runtime path
for agents to actually run work against a remote box
> - That meant agents could be configured around environment concepts
without a reliable way to execute adapter sessions remotely, sync
workspace state, and preserve run context across supported adapters
> - We also need environment selection to participate in normal
Paperclip control-plane behavior: agent defaults, project/issue
selection, route validation, and environment probing
> - Because this capability is still experimental, the UI surface should
be easy to hide and easy to remove later without undoing the underlying
implementation
> - This pull request adds SSH environment execution support across the
runtime, adapters, routes, schema, and tests, then puts the visible
environment-management UI behind an experimental flag
> - The benefit is that we can validate real SSH-backed agent execution
now while keeping the user-facing controls safely gated until the
feature is ready to come out of experimentation

## What Changed

- Added SSH-backed execution target support in the shared adapter
runtime, including remote workspace preparation, skill/runtime asset
sync, remote session handling, and workspace restore behavior after
runs.
- Added SSH execution coverage for supported local adapters, plus remote
execution tests across Claude, Codex, Cursor, Gemini, OpenCode, and Pi.
- Added environment selection and environment-management backend support
needed for SSH execution, including route/service work, validation,
probing, and agent default environment persistence.
- Added CLI support for SSH environment lab verification and updated
related docs/tests.
- Added the `enableEnvironments` experimental flag and gated the
environment UI behind it on company settings, agent configuration, and
project configuration surfaces.

## Verification

- `pnpm exec vitest run
packages/adapters/claude-local/src/server/execute.remote.test.ts
packages/adapters/cursor-local/src/server/execute.remote.test.ts
packages/adapters/gemini-local/src/server/execute.remote.test.ts
packages/adapters/opencode-local/src/server/execute.remote.test.ts
packages/adapters/pi-local/src/server/execute.remote.test.ts`
- `pnpm exec vitest run server/src/__tests__/environment-routes.test.ts`
- `pnpm exec vitest run
server/src/__tests__/instance-settings-routes.test.ts`
- `pnpm exec vitest run ui/src/lib/new-agent-hire-payload.test.ts
ui/src/lib/new-agent-runtime-config.test.ts`
- `pnpm -r typecheck`
- `pnpm build`
- Manual verification on a branch-local dev server:
  - enabled the experimental flag
  - created an SSH environment
  - created a Linux Claude agent using that environment
- confirmed a run executed on the Linux box and synced workspace changes
back

## Risks

- Medium: this touches runtime execution flow across multiple adapters,
so regressions would likely show up in remote session setup, workspace
sync, or environment selection precedence.
- The UI flag reduces exposure, but the underlying runtime and route
changes are still substantial and rely on migration correctness.
- The change set is broad across adapters, control-plane services,
migrations, and UI gating, so review should pay close attention to
environment-selection precedence and remote workspace lifecycle
behavior.

## Model Used

- OpenAI Codex via Paperclip's local Codex adapter, GPT-5-class coding
model with tool use and code execution in the local repo workspace. The
local adapter does not surface a more specific public model version
string in this branch workflow.

## 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

server/src/routes/agents.ts

@@ -23,6 +23,7 @@ import {
   updateAgentInstructionsPathSchema,
   wakeAgentSchema,
   updateAgentSchema,
+  supportedEnvironmentDriversForAdapter,
 } from "@paperclipai/shared";
 import {
   readPaperclipSkillSyncPreference,
@@ -37,6 +38,7 @@ import {
   approvalService,
   companySkillService,
   budgetService,
+  environmentService,
   heartbeatService,
   ISSUE_LIST_DEFAULT_LIMIT,
   issueApprovalService,
@@ -76,6 +78,7 @@ import {
   resolveDefaultAgentInstructionsBundleRole,
 } from "../services/default-agent-instructions.js";
 import { getTelemetryClient } from "../telemetry.js";
+import { assertEnvironmentSelectionForCompany } from "./environment-selection.js";
 
 const RUN_LOG_DEFAULT_LIMIT_BYTES = 256_000;
 const RUN_LOG_MAX_LIMIT_BYTES = 1024 * 1024;
@@ -139,6 +142,17 @@ export function agentRoutes(db: Db) {
   const instanceSettings = instanceSettingsService(db);
   const strictSecretsMode = process.env.PAPERCLIP_SECRETS_STRICT_MODE === "true";
 
+  async function assertAgentEnvironmentSelection(
+    companyId: string,
+    adapterType: string,
+    environmentId: string | null | undefined,
+  ) {
+    if (environmentId === undefined || environmentId === null) return;
+    await assertEnvironmentSelectionForCompany(environmentService(db), companyId, environmentId, {
+      allowedDrivers: allowedEnvironmentDriversForAgent(adapterType),
+    });
+  }
+
   async function getCurrentUserRedactionOptions() {
     return {
       enabled: (await instanceSettings.getGeneral()).censorUsernameInLogs,
@@ -407,6 +421,10 @@ export function agentRoutes(db: Db) {
     return Object.hasOwn(value, key);
   }
 
+  function allowedEnvironmentDriversForAgent(adapterType: string): string[] {
+    return supportedEnvironmentDriversForAdapter(adapterType);
+  }
+
   async function resolveCompanyIdForAgentReference(req: Request): Promise<string | null> {
     const companyIdQuery = req.query.companyId;
     const requestedCompanyId =
@@ -1609,6 +1627,7 @@ export function agentRoutes(db: Db) {
       createInput.adapterType,
       normalizedAdapterConfig,
     );
+    await assertAgentEnvironmentSelection(companyId, createInput.adapterType, createInput.defaultEnvironmentId);
 
     const createdAgent = await svc.create(companyId, {
       ...createInput,
@@ -2065,6 +2084,15 @@ export function agentRoutes(db: Db) {
         effectiveAdapterConfig,
       );
     }
+    if (touchesAdapterConfiguration || Object.prototype.hasOwnProperty.call(patchData, "defaultEnvironmentId")) {
+      await assertAgentEnvironmentSelection(
+        existing.companyId,
+        requestedAdapterType,
+        Object.prototype.hasOwnProperty.call(patchData, "defaultEnvironmentId")
+          ? (typeof patchData.defaultEnvironmentId === "string" ? patchData.defaultEnvironmentId : null)
+          : existing.defaultEnvironmentId,
+      );
+    }
 
     const actor = getActorInfo(req);
     const agent = await svc.update(id, patchData, {