Snapshot dev host cleanup environment

[ScriptedAlchemy]

Summary

• snapshot the dev host install environment and home for the full manager lifecycle
• pass that snapshot to host CLI processes during install and teardown
• prevent callers that restore process.env before server close from redirecting cleanup or making host binaries disappear

Follow-up for #677 after the merged main integration matrix exposed the teardown boundary.

Validation

• pnpm build — passed
• pnpm typecheck — passed
• pnpm lint — passed
• pnpm test:unit — passed
• pnpm exec rstest packages/workbench/tests/sessions.e2e.test.ts — passed on the branch rebased onto Fix development host install lifecycle #677; this is the exact test that failed on all three main integration matrix versions

Deslop

Deslop: GPT-5.6 Sol, 0 edits.

Self-review

Reviewer: Claude Fable 5.1 Thinking High

First pass findings and disposition:

• Blocking: branch initially used a stale origin/main, so the test did not include Fix development host install lifecycle #677. Fixed by fetching and rebasing onto merge commit c2e69f20cc.
• Blocking: snapshotting path calculations alone did not control the environment inherited by host CLI processes. Fixed by passing the snapshot through InstallCommandRunner to execFile.
• Residual: implicit homedir() could still change. Fixed by resolving and retaining home at manager construction.

Second pass: both blockers resolved; no blocking findings. The exact merged-main E2E is the regression guard.

[changeset-bot]

🦋 Changeset detected

Latest commit: 957df36

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
agent-bundle	Patch

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[pkg-pr-new]

npm i https://pkg.pr.new/ScriptedAlchemy/agent-bundle@678

npm i https://pkg.pr.new/ScriptedAlchemy/agent-bundle/create-agent-bundle@678

npm i https://pkg.pr.new/ScriptedAlchemy/agent-bundle/rsc-markdown-stream@678

npm i https://pkg.pr.new/ScriptedAlchemy/agent-bundle/@agent-bundle/runtime@678

commit: 957df36