name: channel-assignment description: Decide whether a new observable channel belongs to P (session shape), X (execution), or E (exogenous) per the DAG §A1-A2. Use when adding a new data field, integrating a new signal, or revisiting an ambiguous assignment.

P / X / E Channel Assignment

Read docs/theoretical_framework.md §A1, §A2 before running.

Decision tree

1. Is the channel selected by the athlete in response to prior state Z_{t-1}?
   • Yes → candidate for P (session shape).
   • No → go to 2.
2. Is the channel produced by the body during execution?
   • Yes → X.
   • No → go to 3.
3. Is the channel genuinely exogenous (⊥ Z_{t-1}, ⊥ P_t) — weather, time-of-day, ambient conditions not selected for interaction with state?
   • Yes → E.
   • No → the channel does not fit the framework as stated. Escalate before integration.

Failure modes to check

• "Exogenous" that is actually selected. Did the athlete pick the start time to avoid heat? Then ToD is not purely E — it has a selection component that partly belongs to P. Flag.
• "P" that is actually executed. Planned distance vs realized distance: planned is P, realized is X. If only realized is recorded, the split is unrecoverable — note this.
• "X" that is actually structural. Average pace over a long run captures both route and execution; it mixes P and X. Decompose before assigning.

Output

• Channel: name, source, units.
• Assignment: P / X / E with one-sentence rationale.
• Exogeneity check (if E): ⊥ Z_{t-1} yes/no; ⊥ P_t yes/no.
• Data-contract update: proposed diff to docs/data_contract.md.
• Downstream consumers to update: list (observation model, deconfounding, state estimation, eval harness).
• Risks / caveats.