Sanitize remote execution envs at the boundary (#5325)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies
> - Adapters spawn CLIs against local, SSH, and sandbox targets,
threading a runtime env through `runAdapterExecutionTargetProcess` and
the SSH/sandbox runners
> - Host identity vars (HOME, TMPDIR, XDG_*, NVM_DIR, PATH) routinely
leak into the env we send to remote targets — sometimes via test probes,
sometimes via runtime config — and break sandboxed/SSH'd CLIs whose own
profiles set those values correctly
> - The sanitization logic existed but lived alongside other helpers in
`server-utils.ts` and was applied piecemeal at adapter callsites, so it
was easy to bypass
> - This pull request lifts the sanitization into a standalone
`remote-execution-env.ts`, applies it at the SSH and sandbox runtime
boundary so every remote spawn goes through it, and removes the
duplicated callsite-level filtering
> - The benefit is identity-bound host env stops leaking across
SSH/sandbox transports regardless of which adapter calls in

## What Changed

- `packages/adapter-utils/src/remote-execution-env.ts`: new module —
single source of truth for which env keys are identity-bound and how to
strip them when the value matches the host's value
- `packages/adapter-utils/src/server-utils.ts`: remove the inline
sanitization (now in `remote-execution-env.ts`)
- `packages/adapter-utils/src/execution-target.ts`: apply sanitization
at the sandbox runtime boundary
- `packages/adapter-utils/src/ssh.ts`: apply sanitization at the SSH
spawn boundary
- `packages/adapters/opencode-local/src/server/test.ts`: drop
now-redundant callsite filtering
- `packages/adapters/pi-local/src/server/test.ts`: drop now-redundant
callsite filtering
- New tests `execution-target.test.ts` and
`execution-target-sandbox.test.ts` cover the sanitizer flow at both
transports, including positive cases (host-shaped path stripped) and
explicit-override preservation

## Verification

- `pnpm vitest run --no-coverage --project @paperclipai/adapter-utils
--project @paperclipai/adapter-opencode-local --project
@paperclipai/adapter-pi-local`
- `pnpm typecheck` clean

## Risks

Low–medium. The sanitization is now applied at one layer (boundary)
instead of N (callsites), so behavior is more consistent. Any adapter
that previously relied on a leaked host var landing on the remote shell
would now see it stripped — but those reliances were what this change
exists to fix.

## Model Used

Claude Opus 4.7 (1M context)

## 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 — new tests at both
transports
- [x] If this change affects the UI, I have included before/after
screenshots — N/A (no UI)
- [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/ssh.ts

@@ -721,6 +721,7 @@ export async function runSshCommand(
   config: SshConnectionConfig,
   remoteCommand: string,
   options: {
+    env?: Record<string, string>;
     timeoutMs?: number;
     maxBuffer?: number;
   } = {},
@@ -730,12 +731,33 @@ export async function runSshCommand(
     const auth = await createSshAuthArgs(config);
     cleanup = auth.cleanup;
     const sshArgs = [...auth.args];
+    const envEntries = Object.entries(options.env ?? {})
+      .filter((entry): entry is [string, string] => typeof entry[1] === "string");
+    for (const [key] of envEntries) {
+      if (!isValidShellEnvKey(key)) {
+        throw new Error(`Invalid SSH environment variable key: ${key}`);
+      }
+    }
+
+    // Mirror buildSshSpawnTarget: source login profiles first, then run
+    // `env KEY=VAL cmd` so user-supplied identity overrides win over anything
+    // a profile re-exports. Without this, a remote profile that resets HOME
+    // / NVM_DIR / etc. would silently undo the explicit env passed in here.
+    const envArgs = envEntries.map(([key, value]) => `${key}=${shellQuote(value)}`);
+    const remoteScript = [
+      'if [ -f "$HOME/.profile" ]; then . "$HOME/.profile" >/dev/null 2>&1 || true; fi',
+      'if [ -f "$HOME/.bash_profile" ]; then . "$HOME/.bash_profile" >/dev/null 2>&1 || true; fi',
+      'if [ -f "$HOME/.zprofile" ]; then . "$HOME/.zprofile" >/dev/null 2>&1 || true; fi',
+      envArgs.length > 0
+        ? `exec env ${envArgs.join(" ")} sh -c ${shellQuote(remoteCommand)}`
+        : `exec sh -c ${shellQuote(remoteCommand)}`,
+    ].join(" && ");
 
     sshArgs.push(
       "-p",
       String(config.port),
       `${config.username}@${config.host}`,
-      remoteCommand,
+      `sh -lc ${shellQuote(remoteScript)}`,
     );
 
     return await execFileText("ssh", sshArgs, {