Time models (normative)

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Lockstep

• A lockstep world MUST declare tick_policy: "on_tick" and MUST advance only in response to world.tick. [AWP-TIM-002]
• After each advance, the world MUST send every action.status and world.event produced by the advance on the control channel before the world.tick result, and MUST send exactly one frame carrying the advance’s tick on every subscribed per-tick channel, before accepting the next advance. The agent MUST treat the advance as complete only when it holds the result and, on every subscribed per-tick channel, a frame whose tick equals the result’s; on the inline binding those frames precede the result. [AWP-TIM-003]
• Wall-clock time MUST NOT influence world state in lockstep mode (determinism requirement; see reproducibility). [AWP-TIM-004]
• Initial observations. Immediately after session.ready, and after every obs.subscribe, the world MUST send one frame carrying the current tick on each newly subscribed per-tick channel, and the agent waits for it before acting, so the agent always observes before it acts. [AWP-TIM-009]
• Staging. action.submit in lockstep is admitted immediately (AWP-LIF-002) and the action is staged: the world MUST NOT begin executing it before the next advance, and MUST transition it to executing at the start of that advance so its first effects appear in the advance’s frames. Cancelling a staged action before the advance has no side effects. [AWP-TIM-010]
• Advances. world.tick { expected_tick, count } performs count sequential advances (default 1) from expected_tick, which MUST equal the world’s current tick; otherwise the call fails with AWP_TICK_MISMATCH carrying the current tick in data.tick and nothing advances, so a call retried after a lost result cannot advance twice. Each advance delivers its frames, statuses, and events as in AWP-TIM-003 before the next begins; the result { tick } is sent after the last. Extended actions spanning several ticks report progress on each advance. [AWP-TIM-011]
• Tick authority. The manifest declares tick_authority: any_session (the default for worlds that admit one lockstep session at a time) or barrier (the default when several lockstep sessions may be bound: the world advances once every bound, non-observer lockstep session has called world.tick for the current tick, delivering the same advance to all). world.tick from a session that lacks authority — an observer session, or a session without the tick admin grant where the world requires one — MUST fail with AWP_TICK_NOT_AUTHORIZED. [AWP-TIM-012]

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Wire trace

// 1. session.open → session.ready (lockstep, subscribed to grid_view)
{ "method": "session.open", "params": { "embodiment": "avatar_0", "mode": "lockstep",
  "subscribe": [ { "channel": "grid_view" } ] } }
{ "result": { "session_id": "sess_01", "session_token": "st_9f2…", "reconnect_window_ms": 30000, "heartbeat_interval_ms": 5000,
  "granted": { "channels": [ { "channel": "grid_view", "rate_hz": null, "channel_id": 1 } ],
               "action_types": ["move"], "envelopes": [], "admin": ["tick"] },
  "stream_endpoints": [ { "binding": "inline" } ], "tick": 0 } }

// 2. Initial observation for tick 0 (AWP-TIM-009)
{ "method": "obs.frame", "params": { "channel_id": 1, "seq": 1, "tick": 0, "ts_mono_ns": 0,
  "flags": 1, "payload_b64": "eyJhdmF0YXIiOlsyLDNdfQ==" } }

// 3. Submit → admitted and staged (AWP-TIM-010)
{ "method": "action.submit", "params": { "action_id": "a-1", "type": "move", "params": { "direction": "north" } } }
{ "result": { "action_id": "a-1", "state": "accepted", "status_seq": 1, "received_ts_mono_ns": 0, "ts_mono_ns": 0 } }

// 4. Advance one tick (AWP-TIM-011). Before the result: statuses, then frames.
{ "method": "world.tick", "params": { "expected_tick": 0, "count": 1 } }
{ "method": "action.status", "params": { "action_id": "a-1", "state": "executing", "status_seq": 2, "ts_mono_ns": 1000000 } }
{ "method": "action.status", "params": { "action_id": "a-1", "state": "completed", "status_seq": 3, "ts_mono_ns": 1000000 } }
{ "method": "obs.frame", "params": { "channel_id": 1, "seq": 2, "tick": 1, "ts_mono_ns": 1000000,
  "flags": 1, "payload_b64": "eyJhdmF0YXIiOlsyLDJdfQ==" } }
{ "result": { "tick": 1 } }

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Streaming

• The world advances in real time regardless of agent activity. Observation frames are pushed at negotiated rates, each carrying its capture time ts_mono_ns and its send time ts_send_ns (AWP-OBS-006); the agent relates them to its own clock through the heartbeat exchange (AWP-CLK-006..009). [AWP-TIM-005]
• Telemetry. In streaming sessions the world MUST send a session.telemetry notification at least once per second aggregating, over the preceding window, the quantities defined in Latency and staleness: pipeline latency overall and per channel, admission latency, observation-to-action latency, and command latency, each present whenever at least one sample fell in the window. [AWP-TIM-006]
• Worlds MUST declare safety_policy.safe_state (behavior and watchdog_ms) and enforce it as specified in Liveness and safe state (AWP-SAF-003..008); worlds MAY declare safety_policy.max_basis_age_ms and then enforce stale-intent rejection (AWP-SAF-013). [AWP-TIM-007]

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Wire trace

// 1. Heartbeat as clock synchronization (AWP-CLK-007/008). Agent clock at send: 5000000; at receipt: 5100000.
//    rtt_ns = (5100000 − 5000000) − (913004050000 − 913004000000) = 50000
//    offset_ns = ((913004000000 − 5000000) + (913004050000 − 5100000)) / 2 = 912998975000
{ "method": "ping", "params": { "origin_ns": 5000000 } }
{ "result": { "origin_ns": 5000000, "receive_ns": 913004000000, "transmit_ns": 913004050000 } }

// 2. Frame captured at 913004112000 and sent 8.2 ms later (AWP-OBS-006)
{ "method": "obs.frame", "params": { "channel_id": 1, "seq": 4211, "ts_mono_ns": 913004112000, "ts_send_ns": 913004120200,
  "flags": 1, "payload_b64": "…" } }

// 3. Submit naming its basis and a 200 ms validity window (AWP-ACT-007); admitted with receipt and transition times (AWP-LIF-002)
{ "method": "action.submit", "params": { "action_id": "a-7", "type": "move_to_pose",
  "params": { "pose": { "frame": "base", "p_m": [0.4, 0.1, 0.3], "q": [0, 0, 0, 1] } },
  "basis_ts_mono_ns": 913004112000, "valid_until_ns": 913004312000 } }
{ "result": { "action_id": "a-7", "state": "accepted", "status_seq": 17, "received_ts_mono_ns": 913004141000, "ts_mono_ns": 913004142100 } }
// observation-to-action latency 29.0 ms; admission latency 1.1 ms — both aggregated into the next telemetry notification

// 4. Telemetry on the control channel, once per second (AWP-TIM-006)
{ "method": "session.telemetry", "params": { "window_ms": 1000,
  "observation_latency_ns": { "count": 30, "p50": 8200000, "p95": 21500000 },
  "admission_latency_ns": { "count": 1, "p50": 1100000, "p95": 1100000 },
  "observation_to_action_ns": { "count": 1, "p50": 29000000, "p95": 29000000 },
  "channels": { "1": { "count": 30, "p50": 8200000, "p95": 21500000 } } } }

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Declaration