v0.9.0

Minor Changes

• 47184de: Capture Claude Code subagent / workflow session transcripts to the host alongside the main session. Previously only the main <sessionId>.jsonl was copied off the sandbox; transcripts written by the Agent tool and the Workflow tool under <sessionId>/subagents/agent-*.jsonl were lost on teardown. They are now captured with the same sandbox→host cwd rewrite. Failure to capture an individual subagent transcript is best-effort and logs a warning; the main session capture remains fatal on failure.

Patch Changes

• 86aec83: sandcastle init now scaffolds CLAUDE_CODE_OAUTH_TOKEN= (with a commented ANTHROPIC_API_KEY= fallback) for the Claude Code agent, and the next-steps copy points users at claude setup-token instead of the closed issue #191.
• 03dcc25: Guard substitutePromptArgs against undefined/null values in promptArgs. Previously, a present-but-nullish value (e.g. { TITLE: undefined } from an orchestrator's JSON.parse output) bypassed the existence check and crashed with an unguarded TypeError on .toString(). Now surfaces a clean PromptError naming the offending key. findMissingPromptArgKeys also treats present-but-nullish values as missing, so the interactive prompt-fill flow asks the user to supply the value rather than failing through.