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/services/execution-workspaces.ts

@@ -203,6 +203,7 @@ export function readExecutionWorkspaceConfig(metadata: Record<string, unknown> |
   if (!raw) return null;
 
   const config: ExecutionWorkspaceConfig = {
+    environmentId: readNullableString(raw.environmentId),
     provisionCommand: readNullableString(raw.provisionCommand),
     teardownCommand: readNullableString(raw.teardownCommand),
     cleanupCommand: readNullableString(raw.cleanupCommand),
@@ -226,6 +227,7 @@ export function mergeExecutionWorkspaceConfig(
 ): Record<string, unknown> | null {
   const nextMetadata = isRecord(metadata) ? { ...metadata } : {};
   const current = readExecutionWorkspaceConfig(metadata) ?? {
+    environmentId: null,
     provisionCommand: null,
     teardownCommand: null,
     cleanupCommand: null,
@@ -240,6 +242,7 @@ export function mergeExecutionWorkspaceConfig(
   }
 
   const nextConfig: ExecutionWorkspaceConfig = {
+    environmentId: patch.environmentId !== undefined ? readNullableString(patch.environmentId) : current.environmentId,
     provisionCommand: patch.provisionCommand !== undefined ? readNullableString(patch.provisionCommand) : current.provisionCommand,
     teardownCommand: patch.teardownCommand !== undefined ? readNullableString(patch.teardownCommand) : current.teardownCommand,
     cleanupCommand: patch.cleanupCommand !== undefined ? readNullableString(patch.cleanupCommand) : current.cleanupCommand,
@@ -260,6 +263,7 @@ export function mergeExecutionWorkspaceConfig(
 
   if (hasConfig) {
     nextMetadata.config = {
+      environmentId: nextConfig.environmentId,
       provisionCommand: nextConfig.provisionCommand,
       teardownCommand: nextConfig.teardownCommand,
       cleanupCommand: nextConfig.cleanupCommand,
@@ -739,6 +743,37 @@ export function executionWorkspaceService(db: Db) {
         .then((rows) => rows[0] ?? null);
       return row ? toExecutionWorkspace(row) : null;
     },
+
+    clearEnvironmentSelection: async (companyId: string, environmentId: string) => {
+      return db.transaction(async (tx) => {
+        const rows = await tx
+          .select({
+            id: executionWorkspaces.id,
+            metadata: executionWorkspaces.metadata,
+          })
+          .from(executionWorkspaces)
+          .where(eq(executionWorkspaces.companyId, companyId));
+
+        let cleared = 0;
+        const updatedAt = new Date();
+        for (const row of rows) {
+          const metadata = (row.metadata as Record<string, unknown> | null) ?? null;
+          const config = readExecutionWorkspaceConfig(metadata);
+          if (config?.environmentId !== environmentId) continue;
+
+          await tx
+            .update(executionWorkspaces)
+            .set({
+              metadata: mergeExecutionWorkspaceConfig(metadata, { environmentId: null }),
+              updatedAt,
+            })
+            .where(eq(executionWorkspaces.id, row.id));
+          cleared += 1;
+        }
+
+        return cleared;
+      });
+    },
   };
 }