Purpose

Explain the selected method completely without re-authoring why the human chose it.

Preconditions

• rigor_profile is submission or writer handoff is explicitly requested.
• Human method choice and result verdicts are recorded in qx_decisions.jsonl.
• Approved code ran and final result/robustness evidence exists.

Sources

Use:

• qx_method_card.md
• qx_decisions.jsonl
• planning/model_assumptions.md
• planning/symbol_table.md
• qx_code_plan.md
• final run summary and result analysis
• robustness summary/report

Read legacy candidate and iteration logs only for migration.

Workflow

1. Resolve the final method and baseline from the latest non-stale human decisions.
2. Transcribe the human's selection rationale faithfully and cite its decision_id.
3. Explain:
   • goal and scope;
   • assumptions, including human-confirmed necessity labels;
   • symbols and units;
   • mathematical formulation;
   • inputs, outputs, objective/criteria, and constraints;
   • solution procedure;
   • baseline and why it is valid;
   • fallback trigger and whether it fired;
   • validation, robustness, limitations, and applicable range.
4. Ensure formulas match code and symbol table.
5. Save methods/Qx/qx_final_method_explanation.md.

Rules

• Do not infer the chosen method from best metrics.
• Do not invent the why-this-method narrative.
• Do not create a new pending decision artifact.
• Do not restate a long iteration diary; include only material eliminated alternatives and evidence.
• Do not include unsupported numerical claims.

Verification

• Final method and rationale trace to decision IDs.
• Assumptions, symbols, formulas, units, and code agree.
• Baseline is usable rather than merely diagnostic.
• Risks, fallback behavior, and limitations are explicit.
• The explanation is self-contained enough for the writer.