BashTool ignores context.workspace for default cwd — sub-agent worktrees run commands in parent checkout

[fleitz]

Problem

When a sub-agent is spawned with worktree: true, shell commands that don't specify an explicit cwd run in the parent checkout's workspace instead of the sub-agent's worktree directory.

The BashTool's cwd resolution defaults to None when no cwd is provided, which falls through to the shared ShellManager's default_workspace (set to the parent workspace). The foreground execution path (execute_foreground_via_background) also always passed None as the working directory, so even if the cwd were resolved differently upstream, it was ignored.

Root Cause

Two issues in crates/tui/src/tools/shell.rs:

1. No-op default: BashTool's working_dir resolution returned None when no cwd was given, deferring to ShellManager.default_workspace instead of context.workspace.
2. Missing thread: execute_foreground_via_background hardcoded None as the working directory, so it couldn't receive a resolved directory even if one were provided.

Fix (PR #4673)

• Default no-cwd shell commands to context.workspace instead of None.
• Thread the resolved working_dir through execute_foreground_via_background.
• Added regression test default_cwd_uses_context_workspace_not_shell_manager_default.

Expected Behavior

Shell commands without an explicit cwd should run in the sub-agent's worktree directory when worktree: true is used.

/cc @fleitz

[github-actions]

Thanks @fleitz for the report.

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