flowchart TB
    REQ["Agent wants\nto act"]
    CHECK{"HITL\nTier?"}

    T0["Tier 0: BLOCKED\nAgent cannot act\nHuman decides directly"]
    T1["Tier 1: APPROVE BEFORE\nAgent proposes action\nHuman must approve first"]
    T2["Tier 2: REVIEW AFTER\nAgent acts immediately\nHuman reviews async"]
    T3["Tier 3: AUTONOMOUS\nAgent acts and logs\nNo mandatory review"]

    HUMAN["Human\ndecides"]
    APPROVE{"Human\napproves?"}
    EXEC_T1["Execute\n+ Audit"]
    REJECT["Reject\n+ Log reason"]
    EXEC_T2["Execute immediately\n+ Audit + Queue review"]
    EXEC_T3["Execute immediately\n+ Audit only"]

    REQ --> CHECK
    CHECK -->|0| T0 --> HUMAN
    CHECK -->|1| T1 --> APPROVE
    CHECK -->|2| T2 --> EXEC_T2
    CHECK -->|3| T3 --> EXEC_T3

    APPROVE -->|yes| EXEC_T1
    APPROVE -->|no| REJECT

    style T0 fill:#c62828,color:#fff
    style T1 fill:#e65100,color:#fff
    style T2 fill:#1565c0,color:#fff
    style T3 fill:#2e7d32,color:#fff
    style EXEC_T1 fill:#2e7d32,color:#fff
    style EXEC_T2 fill:#2e7d32,color:#fff
    style EXEC_T3 fill:#2e7d32,color:#fff
    style REJECT fill:#c62828,color:#fff
    style HUMAN fill:#b71c1c,color:#fff
