[P0.4] Builtin (react/plan) engines ignore the worktree `workspace_path` — isolation is a silent no-op

[frankbria]

Severity: high | Category: data-integrity | Phase: P0.4

Problem

BuiltinReactAdapter.run(...workspace_path...) never uses workspace_path; it builds ReactAgent(workspace=self._workspace) (the original repo). So --isolation worktree with the default engine edits the MAIN repo and deletes an untouched worktree. The batch path additionally spawns cf work start with cwd=worktree where .codeframe/ doesn't exist → FileNotFoundError, failing every worktree-isolated batch task.

Evidence

codeframe/core/adapters/builtin.py:68

Acceptance criteria

• Builtin engines thread workspace_path into ReactAgent/Agent tool + lint execution, OR worktree isolation is hard-rejected for builtin engines with a clear error.
• Batch worktree path passes the workspace root explicitly instead of relying on cwd.

Dependencies

blocked by #714 ([P0.3])

---

_{Filed from the SaaS launch-readiness audit. Atomic: one developer, one session. Work order: strictly P0.1 → P3.12 (no forward dependencies).}

[coderabbitai]

🔗 Related PRs

#363 - feat: wire ReactAgent into runtime with --engine react CLI flag [merged]
#441 - feat(core): worktree-per-task isolation for parallel batch execution [merged]
#536 - feat(core): ExecutionContext abstraction for task isolation (#532) [merged]
#537 - feat(core): WorktreeRegistry, orphan cleanup, and get_base_branch (#533) [merged]
#705 - fix(security): workspace path allowlist + session ownership (#655) [merged]

---

📝 Issue Planner

_{Check the box below or use the @coderabbitai plan command to generate an implementation plan and prompts that you can use with your favorite coding assistant.}

• Create Plan

---

🧪 Issue enrichment is currently in open beta.

To disable automatic issue enrichment, add the following to your .coderabbit.yaml:

issue_enrichment:
  auto_enrich:
    enabled: false

💬 Have feedback or questions? Drop into our discord!

[frankbria]

Resolved by #714. The bug here (builtin engines ignore workspace_path → --isolation worktree edits the main repo; batch cwd=worktree FileNotFoundError) is only reachable when worktree isolation is active. #714 hard-rejects --isolation worktree for all engines at the single chokepoint (create_execution_context, used by both runtime and conductor) plus both CLI commands, so this path is now unreachable — which is exactly the AC's sanctioned alternative ('OR worktree isolation is hard-rejected for builtin engines with a clear error').

The real workspace_path-threading work is only meaningful when re-enabling worktree, so it's folded into #787 (which now also needs a real test). Closing as resolved-by-#714.