Migrate SSH environment callback to bridge (#5116)

> **Stacked PR (part 3 of 7).** Depends on:
  - PR #5114
  - PR #5115
> Diff against `master` includes commits from earlier PRs in the stack —
the new commit in this PR is the topmost one.

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies
> - Agents executing on a remote SSH-backed environment need a way to
call back into
>   the Paperclip control plane (run events, log streaming, signals)
> - When the SSH host can't reach the Paperclip host (NAT, firewalls, or
simply not
> on the same network), the run silently fails or hangs — a recurring
class of
>   failure during SSH testing
> - In sandboxed environments we already solved this with a callback
bridge that
> tunnels back through the existing connection; SSH was the odd one out
> - This PR migrates SSH execution to use the same callback bridge, so
every
> adapter's remote run uses one consistent reverse-channel. Per-adapter
SSH glue
> is deleted in favour of a shared `CommandManagedRuntimeRunner` built
from the
>   SSH spec
> - The benefit is fewer SSH-specific failure modes, a smaller code
surface, and
>   one place to evolve the callback contract going forward

## What Changed

- Added `createSshCommandManagedRuntimeRunner` in
`packages/adapter-utils/src/ssh.ts` that adapts an SSH spec into a
generic
  command-managed-runtime runner (with cwd, env, and timeout handling)
- Removed `paperclipApiUrl` from `SshRemoteExecutionSpec`; the bridge
URL now flows
  through the shared runner
- Reworked `execution-target.ts` to use the SSH runner alongside sandbox
runners
  via a unified `CommandManagedRuntimeRunner` interface
- Simplified `remote-managed-runtime.ts` and
`sandbox-managed-runtime.ts` to consume
  the shared runner abstraction
- Deleted per-adapter SSH callback wiring from claude-local,
codex-local,
  cursor-local, gemini-local, opencode-local, pi-local execute.ts files
- Removed `environment-runtime-driver-contract.test.ts` (the contract is
now
  enforced by `environment-execution-target.test.ts`)
- Added/updated `execute.remote.test.ts` cases for each adapter to cover
the SSH
  runner path

## Verification

- `pnpm --filter @paperclipai/adapter-utils test`
- `pnpm test -- execute.remote` (covers all six local adapters' SSH
paths)
- Manual QA: ran a claude-local agent against an SSH-backed environment,
confirmed
the agent successfully called back to `/api/agent-callback/*` endpoints
during
  the run

## Risks

- Refactor touches all six local adapters. If any adapter had subtle
SSH-specific
behaviour that wasn't captured in tests, it could regress. Mitigation:
each
  adapter's `execute.remote.test.ts` was extended.
- `paperclipApiUrl` removal from `SshRemoteExecutionSpec` is a breaking
type change
for any internal consumer. Verified no external plugins consume this
type.
- The new `CommandManagedRuntimeRunner` shape is a public surface in
`@paperclipai/adapter-utils`; downstream plugins implementing custom
runners may
  need updates, but no such plugins exist in this repo.

## Model Used

- OpenAI GPT-5.4 (reasoning effort: high) via Codex CLI
- Provider: OpenAI
- Used to author the code changes in this PR

## 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 — N/A
- [ ] I have updated relevant documentation to reflect my changes — N/A
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

server/src/__tests__/environment-execution-target.test.ts

@@ -54,14 +54,11 @@ describe("resolveEnvironmentExecutionTarget", () => {
       remoteCwd: DEFAULT_SANDBOX_REMOTE_CWD,
       leaseId: "lease-1",
       environmentId: "env-1",
-      paperclipTransport: "bridge",
       timeoutMs: 30_000,
     });
   });
 
-  it("prefers an explicit Paperclip API URL from lease metadata for sandbox targets", async () => {
-    process.env.PAPERCLIP_API_URL = "https://paperclip.example.test";
-    process.env.PAPERCLIP_RUNTIME_API_URL = "http://paperclip.example.test:3200";
+  it("keeps sandbox targets on bridge mode even when lease metadata includes a Paperclip API URL", async () => {
     mockResolveEnvironmentDriverConfigForRuntime.mockResolvedValue({
       driver: "sandbox",
       config: {
@@ -93,9 +90,11 @@ describe("resolveEnvironmentExecutionTarget", () => {
     expect(target).toMatchObject({
       kind: "remote",
       transport: "sandbox",
-      paperclipApiUrl: "https://paperclip.example.test",
-      paperclipTransport: "direct",
+      providerKey: "fake-plugin",
+      remoteCwd: DEFAULT_SANDBOX_REMOTE_CWD,
     });
+    expect(target).not.toHaveProperty("paperclipApiUrl");
+    expect(target).not.toHaveProperty("paperclipTransport");
   });
 
   it("passes through a provider-declared sandbox shell command from lease metadata", async () => {
@@ -133,4 +132,50 @@ describe("resolveEnvironmentExecutionTarget", () => {
       shellCommand: "bash",
     });
   });
+
+  it("resolves SSH execution targets in bridge mode", async () => {
+    mockResolveEnvironmentDriverConfigForRuntime.mockResolvedValue({
+      driver: "ssh",
+      config: {
+        host: "ssh.example.test",
+        port: 22,
+        username: "paperclip",
+        remoteWorkspacePath: "/srv/paperclip",
+        privateKey: "PRIVATE KEY",
+        knownHosts: "[ssh.example.test]:22 ssh-ed25519 AAAA",
+        strictHostKeyChecking: true,
+      },
+    });
+
+    const target = await resolveEnvironmentExecutionTarget({
+      db: {} as never,
+      companyId: "company-1",
+      adapterType: "codex_local",
+      environment: {
+        id: "env-ssh-1",
+        driver: "ssh",
+        config: {},
+      },
+      leaseId: "lease-ssh-1",
+      leaseMetadata: {},
+      lease: null,
+      environmentRuntime: null,
+    });
+
+    expect(target).toMatchObject({
+      kind: "remote",
+      transport: "ssh",
+      remoteCwd: "/srv/paperclip",
+      leaseId: "lease-ssh-1",
+      environmentId: "env-ssh-1",
+      spec: {
+        host: "ssh.example.test",
+        port: 22,
+        username: "paperclip",
+        remoteWorkspacePath: "/srv/paperclip",
+        remoteCwd: "/srv/paperclip",
+      },
+    });
+    expect(target).not.toHaveProperty("paperclipApiUrl");
+  });
 });