chemthermo-change-loop

name: chemthermo-change-loop description: Use when implementing or reviewing changes in this Chemical-Thermodynamics repository. Apply the repo contract by reading .agents/brain/brain.md first, preserving SI-unit and public-API invariants, shipping thin vertical slices with a runnable golden path, running CI-equivalent quality gates (ruff format, ruff format --check, ruff check, pyright, pytest), verifying editable and non-editable install smoke checks, and updating ADR/brain docs when architecture or public API changes.

Chemthermo Change Loop

Inputs

• User request and acceptance criteria
• Files expected to change
• Whether public API or architecture boundaries are affected
• Local environment status (Python 3.11+, editable install)

Workflow

1. Establish scope and constraints.

• Read README.md and .agents/brain/brain.md before structural edits.
• If the change is architectural or API-facing, read relevant ADRs in .agents/brain/adr/.
• Confirm scope policy remains consistent across docs: VLLE and PC-SAFT are in scope, and no thermodynamic capability class is categorically out of scope.

2. Classify the change.

• Treat edits touching src/chemthermo/__init__.py, src/chemthermo/eos/__init__.py, or src/chemthermo/vlle/__init__.py as public API-sensitive.
• Treat changes to solver/model internals as invariant-sensitive (SI units, composition validation, deterministic flash behavior).
• Treat notebook edits as hygiene-sensitive (strip outputs, keep runnable narrative).

3. Implement a thin vertical slice.

• Prefer the smallest end-to-end usable increment over scaffold-only work.
• Declare the slice explicitly before implementation: "After this change, user can X by running Y."
• Keep interfaces and behavior coherent across code, tests, and examples.
• Avoid opportunistic refactors unrelated to the requested change.

4. Validate in escalating order.

• Run focused tests for touched modules first.
• Run canonical bootstrap, CI gates, and golden path from .agents/dev-contract.md.
• Run installability checks from .agents/dev-contract.md (pip install -e ".[dev]" path and pip install . smoke via tools/smoke_install.py).
• Use the cheap-check subset in .agents/dev-contract.md during iteration, then run full CI gates before finalizing.
• If validation extras are installed, run optional reference checks under tests/validation/.

5. Update docs and decision records.

• Update README/examples/notebooks docs when user-visible behavior changes.
• Update .agents/brain/steering-brief.md when architecture context changes.
• Add or update an ADR for public API or architectural decisions.

6. Report outcomes clearly.

• Summarize what changed, what was validated, and any known risks.
• Include thin-slice evidence from .agents/dev-contract.md (slice declaration, golden path, focused tests, CI checks, install smoke).
• If any checks were skipped, state exactly which checks and why.

Mandatory completion checklist (hard gate)

• Slice declaration is present: "After this change, user can X by running Y."
• At least one golden-path command/test was run and outcome reported.
• Focused tests for touched behavior were run and outcomes reported.
• CI-equivalent checks were run and outcomes reported.
• Editable and non-editable install smoke checks were run and outcomes reported.
• User-visible behavior changes include docs updates in the same slice.

Notebook-specific checklist

• Keep notebooks in notebooks/ runnable top-to-bottom.
• Preserve concise markdown context for each code block.
• Ensure outputs are stripped before commit (nbstripout workflow).
• Keep supporting utilities in notebooks/_nb_utils.py or regular modules when reuse is needed.

Guardrails

• Do not invent thermodynamic constants, component data, or external-reference results.
• Do not loosen CI or invariant checks unless explicitly requested.
• Keep commits small and logically grouped.
• Keep the working tree clean at handoff.