[alhermann]

Problem

The served Dirichlet–Neumann participant templates export normal_fluxes, and dump them into interface_level<k>.csv, as minus the conormal derivative on their own outward normal:

• heat: -(k grad u) · n_own, which is the outward normal flux;
• elasticity: -(σ · n_own), which is minus the outward traction.

That convention is right for the exchange. But the instructions that send the agent from these columns to the files its task asks for, after a converged coupling, said nothing about the sign. So a file that asked for the outward traction σ · n received its negative. The coupled solution itself was not affected; only the reported interface traction was.

What this changes

What the coupling exchanges is unchanged. Every place that points the agent from the exported columns to its own output files now states the sign:

• coupling_knowledge:
  • adds FLUX_COLUMNS_SIGN (the rule, per contract kind) and FLUX_COLUMNS_SIGN_SHORT (one sentence for text repeated per level);
  • the vector contract (section 6a, rule 2) and the elastic variant's intro say that the outward traction is -q.
• consolidated:
  • the rule is in couple_levels' all-converged next_step and in couple()'s reporting;
  • the interface tables' _how_to_use carries the short rule;
  • the converged-level leads, the SAVE-VERBATIM verdict and the couple docstring qualify the q columns;
  • interface tables name one column per entry (x, y, u1, u2, q1, q2) where six columns were headed x, y, u, qn;
  • the thermo-elastic exchange is written [q_n, q_x, q_y] (also in the 4C deck grammar note).
• result_audit:
  • the rule appears in the deliverables brief (ladder step 4) and in the missing-fields finding;
  • the deliverable-flux finding says what the q columns hold.
• Elastic participant contracts (FEniCSx, DUNE-fem, FEBio):
  • the console line names the exported traction qx, qy with its definition, instead of tx, ty;
  • FEBio's dump block states what its qx, qy columns hold, as the others do.

Tests

New: tests/test_exchanged_traction_is_not_the_outward_traction.py. It runs:

• the scikit-fem elastic contract, for both interface orientations and both roles;
• the scikit-fem heat contract;
• a real converged couple_levels and couple of two elastic sides.

The contracts run on fields with closed-form stress and flux, and the test checks the replies against the measured columns.

Local run on this branch, which is on top of main (da6f80a):

• pytest tests/, without the LangGraph test: 99 passed, 13 skipped;
• tests/test_web_search_reports_a_block.py in the LangGraph environment: 11 passed.

🤖 Generated with Claude Code

[Copilot]

🟢 Approval recommended

The reporting and header changes preserve numerical exchange behavior, with regression coverage and no identified blocking issues.

0 open findings

What changed in this PR

Clarifies how openPASO converts exported interface fluxes into reported quantities, without changing the numerical exchange.

Changes:

• States that elastic outward traction is -q throughout reporting guidance.
• Gives vector CSV columns individual names and clarifies participant log labels.
• Adds regression tests for flux signs and converged coupling replies.

File	Description
tests/​test_exchanged_traction_is_not_the_outward_traction.py	Tests sign conventions and reporting guidance.
src/​tools/​result_audit.py	Adds sign guidance to deliverable instructions.
src/​tools/​coupling_knowledge.py	Defines shared flux-sign explanations.
src/​tools/​consolidated.py	Updates reporting guidance and vector CSV headers.
src/​backends/​fourc/​deck_grammar.py	Clarifies exchange notation in documentation.
data/​coupling_participants/​participant_fenics_elastic.py	Clarifies exported traction log labels.
data/​coupling_participants/​participant_febio_elastic.py	Clarifies log labels and dump comments.
data/​coupling_participants/​participant_dune_elastic.py	Clarifies exported traction log labels.

🧠 Review effort: Balanced

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