Cosmos3 Nano Policy troubleshooting - Reactor

Symptom	Check
Connection rejected or no capacity	Use `https://api.reactor.inc`, the correct model identifier, and an authorized key. Capacity errors can occur before inference; retry with backoff or contact Reactor.
No first chunk	Wait for `READY` before publishing. All three named tracks must deliver frames, and `proprio_json` must parse as row lists.
No next chunk	Acknowledge the last received `step` after execution. Repeating or lowering the acknowledged counter does not open the gate.
State ignored	Encode JSON as a string inside the named command payload. Check the 8,000-character limits and row widths.
Correct shape, wrong motion	Check camera identities, joint ordering/units, and absolute-target interpretation. Tensor shape does not prove embodiment compatibility.
Gripper moves the wrong way	DROID uses `0` open and `1` closed. Convert your driver’s units/polarity explicitly.
Values differ on identical inputs	Sampling is unseeded and video transport can change the received pixels; exact numerical equality is not a supported check.
Unexpected step after reset	Reset restarts the counter but preserves input fields. Use a new session when old acknowledgements or replies could be mistaken for new ones.

Reference-client behavior

Keep the event loop responsive so camera publishing and message handling can continue. Start a fresh session after an uncertain timeout; do not fabricate an acknowledgement to force progress. The documented endpoint supports reset as specified in the reference.

Report a problem

Include the model identifier, SDK/client versions, session ID, timestamps, track names/shapes, proprioception dimensions, last received and acknowledged counters, and exact error text. Never include an API key. State whether the failure occurred during connection, first prediction, or subsequent control steps.

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