Flow replay cache

Flow replay cache — contract and behavior

• Replay stores action-level interaction structure, not a reusable authenticated browser session.
• A replay attempt validates the expected page state and stops when selectors or transitions no longer match.
• Failed replay falls back to the normal trajectory/agent path and records why the cached flow was not usable.
• Cache identity includes the action context needed to prevent a flow for one platform or lifecycle stage from leaking into another.