fix(svdsbtl): skip patch polish for two-phase points

[ibell]

Summary

polish_patch_state_ runs a forward-h TOMS748 polish on every HmassP / HmolarP probe that lands inside the critical-patch bbox, on the assumption that a single-phase solution exists at h(T, p) = h_target on a tight T bracket around T_seed. Inside the saturation dome h(T, p) is multi-valued (it jumps from h_L to h_V across T = T_sat), so the bracket [T_seed-0.5, T_seed+0.5] straddles the dome and resid changes sign without any single-phase root in the range. TOMS748 silently converges to a nonsense T, and the returned state classifies as supercritical_liquid with rho / Q = ±inf.

The auto-calibrated patch bbox for non-water fluids whose critical region overlaps a wide h-range (R245fa, R134a, …) has its HmassP envelope straddle the saturation dome by construction, so any two-phase probe inside the patch hits the failure mode.

This skips the polish entirely when the patched state is iphase_twophase — two-phase points coming out of the patch already have correct (T_sat, Q, rho) from the source's PQ-blend; the forward-h polish was only designed for the ±25 mK backward-equation residual of IF97's single-phase formulations.

Reproducer (R245fa, before the fix):

HmassP probe: h=450.7e3 J/kg, p=2.89e6 Pa   (Q=0.5 dome point)
HEOS truth :  rho = 346.65, phase = twophase, Q = 0.500
SVDSBTL    :  rho = -inf,   phase = sc_liq,   Q = -inf

After the fix all 6 sweep probes (T = 0.96 … 0.999 · Tc, Q = 0.5) match HEOS within ~1e-14.

Test plan

• CatchTestRunner "[SVDSBTL]" — 40 passed / 6 skipped / 0 failed
• Spot-checked R245fa near-critical dome at T/Tc ∈ {0.96, 0.97, 0.98, 0.99, 0.995, 0.999} — all within ~1e-14 of HEOS
• No regressions on single-phase in-patch points (polish path still runs)

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Avoided applying single-phase polishing to points originating from two-phase sources, reducing incorrect or multi-valued results near saturation boundaries.
  • Patched points now reliably inherit and report their source phase after updates, with added safeguards for sources that may not expose phase information.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: f73eda43-84d3-4aee-8389-6297c1bbd425

📥 Commits

Reviewing files that changed from the base of the PR and between ae72c74 and ef6fb1a.

📒 Files selected for processing (1)

• src/Backends/SVDSBTL/SVDSBTLBackend.cpp

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📝 Walkthrough

Walkthrough

Adds phase-aware guards to skip forward-h polishing when the patch source is two-phase, and sets a patched point's phase from patch_source->phase() (with try/catch) instead of leaving it as not-imposed.

Changes

Two-phase critical-patch polishing guards & phase propagation

Layer / File(s)	Summary
Guard polish_patch_state_ for two-phase sources src/Backends/SVDSBTL/SVDSBTLBackend.cpp	Wraps calls to polish_patch_state_ in patch_source_->phase() != iphase_twophase checks for HmolarP_INPUTS (via HmassP_INPUTS using *pt.h_mass, *pt.p) and HmassP_INPUTS; PT_INPUTS behavior unchanged.
Set PointEvaluation _phase from patch source src/Backends/SVDSBTL/SVDSBTLBackend.cpp	When update() resolves a point as PointEvaluation::Kind::Patched, sets _phase = patch_source_->phase() inside a try/catch instead of leaving _phase as iphase_not_imposed on success.

Poem

I’m a rabbit in CoolProp’s glade,
Skipping polish where two-phase is made,
I pass along the phase with care,
So patched points know what they bear—
Hops, checks, and tidy state declared. 🐇✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title directly matches the main change: skipping patch polish for two-phase points in the SVDSBTL backend.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ihb/svdsbtl-skip-polish-twophase

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/Backends/SVDSBTL/SVDSBTLBackend.cpp`:
- Around line 541-546: The patched branch preserves a genuine two-phase patch in
patch_source_ but update() fails to propagate that into the internal _phase,
leaving _phase as iphase_not_imposed; inside the PointEvaluation::Kind::Patched
handling (where only iQ is copied currently) update the code to also copy
patch_source_->phase() into _phase (and any other phase-tracking members used by
state.phase()), so that state.phase() matches the preserved patch_source_ phase
after polish_patch_state_ and in the subsequent logic that relies on _phase.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: b97efb04-709e-4b02-8d06-77747fb1ddbf

📥 Commits

Reviewing files that changed from the base of the PR and between 9e57158 and 330dd04.

📒 Files selected for processing (2)

• .beads/issues.jsonl
• src/Backends/SVDSBTL/SVDSBTLBackend.cpp