SystemPromptInvocation class sealed

Describes how a given TCliTool accepts a system prompt for a non-interactive launch.

Sealed hierarchy consumed by the spawn pipeline's argv composer:

• SystemPromptArgv — tool accepts the system prompt via a flag (inline-text or file-path; the distinction lives inside TCliTool.systemPromptInvocation(...) and is already collapsed into a resolved argv fragment here).
• SystemPromptConfigFile — tool configures the system prompt via a file written outside the CLI invocation. Carries the absolute path + contents the consumer must persist plus any argv fragment the launch still requires (often empty).
• SystemPromptUnsupported — tool has no documented non-interactive mechanism. The consumer raises a domain exception.

Instances are ephemeral: created inside TCliTool.systemPromptInvocation and consumed once by SpawnService before being discarded. No serialization, no persistence, no equality semantics expected.