FPF Agent Stack

Feature: AgentFS sandbox isolation and auditing All file modifications must occur in an AgentFS copy-on-write session and be auditable. @agentfs @audit Scenario: Changes do not affect the host workspace Given the host workspace contains a file "README.md" with text "original" And an AgentFS session is started for the workspace When the tool "write_file" writes "README.md" with text "modified" inside the session Then reading "README.md" inside the session should return "modified" And reading "README.md" in the host workspace should return "original" @agentfs @audit Scenario: Every operation appears in the audit log Given an AgentFS session is started for the workspace When the tool "write_file" writes "notes.txt" with text "hello" Then the AgentFS audit log should include an entry for "write_file" And the audit log entry should include the path "notes.txt"