[ChrisRackauckas-Claude]

Please ignore until reviewed by @ChrisRackauckas.

What changed and why

GROUP=SymbolicIndexingInterface on SciMLBase.jl is red (CI run https://github.com/SciML/SciMLBase.jl/actions/runs/35839187919, job "SymbolicIndexingInterface (julia 1)"), from test/downstream/comprehensive_indexing.jl:103: init(ssprob, DynamicSS(Tsit5()); save_everystep = false) on an MTK-lowered SCC steady-state problem throws FieldError: type SCCNonlinearProblem has no field u0.

Root cause: DynamicSS and SICNM only had __solve here, not __init. init(ssprob, DynamicSS(...)) therefore had no matching __init in this package, so it fell through to NonlinearSolveBase's generic fallback, which — because DynamicSS/SICNM are not AbstractNonlinearAlgorithms — treats "no algorithm-specific __init exists" the same as "no algorithm was given" and rewrites the call to NonlinearSolve.jl's default-algorithm converter with ::Nothing in place of the algorithm, silently discarding DynamicSS/SICNM entirely:

# NonlinearSolve.jl src/default.jl
function SciMLBase.__init(prob::SciMLBase.AbstractSteadyStateProblem, ::Nothing, args...; kwargs...)
    nlprob = SciMLBase.NonlinearProblem(prob)
    return SciMLBase.__init(nlprob, nothing, args...; kwargs...)
end

For a plain SteadyStateProblem, NonlinearProblem(prob) still finds an actual NonlinearProblem to hand off to, so init "worked" but silently ignored the requested algorithm. For a SteadyStateProblem whose lowered_problem is an SCCNonlinearProblem (what ModelingToolkit.jl produces for an SCC-decomposable steady-state system, SciML/ModelingToolkit.jl#5155), NonlinearProblem(prob) returns that SCCNonlinearProblem verbatim (correct, already tested in test/scc.jl), and the second NonlinearProblem call — on the already-SCC result — hits SCCNonlinearProblem's missing u0 field. This is the reported FieldError.

Fix

Add SciMLBase.__init(prob::AbstractSteadyStateProblem, alg::DynamicSS/SICNM, ...), mirroring the existing __solve methods (the shared setup is factored into __dynamicss_ode_setup/__sicnm_ode_setup helpers to avoid duplicating the ~40/~90 line problem-construction blocks):

• For a plain problem (or a non-SCC lowering), it returns the live ODE/DAE integrator, so init/solve!/step! compose the way they do for a plain ODEProblem — solve!(init(prob, alg)) == solve(prob, alg).
• For an SCC lowering there is no single integrator to hand back — the blocks solve sequentially (SciMLBase.solve(::SCCNonlinearProblem, ::Union{DynamicSS,SICNM}, ...), already existing) — so it is solved eagerly and the finished solution is returned in place of an integrator, mirroring how a stored NonlinearProblem/LinearProblem lowering is already returned verbatim elsewhere in this file ("stored problem is used verbatim" in SciMLBase's own test suite).

Being a method with a concretely-typed second argument (alg::DynamicSS/alg::SICNM), ordinary Julia dispatch picks it over NonlinearSolveBase's untyped (prob::AbstractNonlinearProblem, args...) fallback, so the buggy conversion path in NonlinearSolve.jl is never reached for these two algorithms at all — this fix does not depend on SciML/SciMLBase.jl#1614 or SciML/NonlinearSolve.jl#1327 (confirmed below; those two are a separate, general-purpose hardening of the "no algorithm given" default path itself).

Verification

Standalone reproducer (init/solve on a manually-built SteadyStateProblem whose lowered_problem is an SCCNonlinearProblem, no ModelingToolkit needed to hit the same dispatch):

Fail-before (unmodified SciMLBase.jl + unmodified SteadyStateDiffEq.jl + unmodified NonlinearSolve.jl):

Calling init(ssprob, DynamicSS(Tsit5())) ...
ERROR: LoadError: FieldError: type SCCNonlinearProblem has no field `u0`, ...
  [3] __init(prob::SCCNonlinearProblem{...}, ::Nothing, args::DynamicSS{...}; ...)
      @ NonlinearSolve .../src/default.jl:61

(matches the CI trace exactly)

Pass-after (this branch + unmodified SciMLBase.jl + unmodified NonlinearSolve.jl — i.e. this fix alone, no companion PRs needed):

Calling init(ssprob, DynamicSS(Tsit5())) ...
init succeeded: NonlinearSolution{...}
Calling solve(ssprob, DynamicSS(Tsit5())) ...
solve succeeded: retcode = Success, u = [-1.9999998629049913]

(u0 = [1.0] converges to the correct root -2.0 of u² = 4, confirming a real solve happened, not just an echoed initial guess)

This repo's own test suite (GROUP=Core, tail):

     Testing SteadyStateDiffEq tests passed

All 427 existing assertions in test/scc.jl still pass unchanged (the __solve refactor into shared helpers is behavior-preserving), plus 16 new assertions added in a new "init on DynamicSS/SICNM does not fall through to NonlinearSolve's default" testset covering: a plain SteadyStateProblem (init returns a live integrator, solve! reproduces the right answer), a manually-built SCCNonlinearProblem lowering, and a real ModelingToolkit SCC decomposition (mirroring the existing "DynamicSS/SICNM on a SteadyStateProblem with an SCC lowering" solve-based testsets, but via init).

Runic --check and typos are clean on both changed files.

What I did not verify

• Did not build the full downstream GROUP=SymbolicIndexingInterface environment from SciMLBase.jl itself (needs a specific newer ModelingToolkit/ModelingToolkitBase resolution); the standalone reproducer above isolates the identical dispatch chain and stacktrace without that heavy environment.
• Did not run GROUP=QA (Aqua/ExplicitImports).

Related

• Raise a clear ArgumentError converting an SCCNonlinearProblem to NonlinearProblem SciMLBase.jl#1614 — fixes a related but independent latent defect: NonlinearProblem(::SCCNonlinearProblem) threw an opaque FieldError; now raises a clear ArgumentError instead. Not required for this PR (this PR's fix stands alone against unmodified SciMLBase).
• Guard against infinite recursion when NonlinearProblem(prob) makes no progress NonlinearSolve.jl#1327 — an earlier companion PR guarding a recursion hazard from a since-abandoned identity-based version of #1614; closed as unnecessary once #1614 was changed to raise an error instead (an error cannot recurse).
• Original CI failure: https://github.com/SciML/SciMLBase.jl/actions/runs/35839187919

🤖 Generated with Claude Code

https://claude.ai/code/session_01NB3oFTNzGW79UtDt8AyjsM

Risk assessment

• Risk: medium
• Blast radius: Anyone who calls init on a SteadyStateProblem with DynamicSS or SICNM. Code that only calls solve is unaffected, because the __solve refactor preserves behaviour: master's 411 scc.jl assertions all still pass. Known downstream caller: SciMLBase test/downstream/comprehensive_indexing.jl:103. That test only builds ssint; it never adds it to integrators, so it only checks that init does not throw. What init returns changes:
  • Before: when it didn't error, it silently ignored the algorithm and fell through to NonlinearSolve's default.
  • Now, plain problem: a raw ODEIntegrator.
  • Now, SCC lowering: a finished NonlinearSolution.
• Evidence: Head e9bfe04b97327d5984f8a8a349964fdbb66f1acd has 0 commits behind master d81bcf1818a7b3735638579ca067f070bd525c33. No check fails on either commit, so nothing needs a pre-existing comparison.
  • Head, all green: Tests - Core (Julia 1 / Julia 1 x86 / Julia lts / Julia pre), Tests - QA (Julia 1), tests/detect, Build and Deploy Documentation, Runic Format Check, Runic Suggestions, Spell Check with Typos, benchmark (1) and (lts).
  • Master: the same test, QA, docs and Runic checks are green.
  • Julia pre is not real coverage on either commit: it logs "Julia 1.13.0 is not a release candidate … skipping build+test and reporting the pre lane as passing".
  • Test counts (Core, Julia 1): Core/scc.jl goes from 411 on master to 427 on head, so the 16 new assertions really ran. The description is wrong to call 427 the existing count. Core/autodiff.jl runs 0 tests on both commits (already true on master).
  • Undisclosed or wrong in the description:
    1. It claims solve!(init(prob, alg)) == solve(prob, alg). That is false. On a plain problem, solve! returns an ODESolution, not a NonlinearSolution, and for SICNM the state is the extended [y; z]. The new test has to slice sol.u[end][1:1] for exactly this reason.
    2. save_idxs is accepted but silently ignored in the non-SCC __init path.
    3. On an SCC lowering, init returns a finished solution rather than an integrator. So init returns a different type depending on the lowering, and solve!/step! on that result won't work.
    4. Replacing the silent fallback to NonlinearSolve's default with an ODE integrator changes what callers get back, and the description never flags this as a behaviour change.
  • No problems found here: no non-public dependency internals are used (only the SciMLBase.__init/__solve extension points and helpers local to the package). No tests were weakened or skipped.
  • Style: about 16% of added lines are comments, above the ~10% guideline. The test-file comment is retrospective ("init had no … dispatch, so it fell through…"). One comment says "see its docstring" but points at a plain comment, not a docstring.
  • Other: no review comments on the PR, and it is still a draft.
• Independent review: Devin CLI 3000.11.3 / fusion-claude-opus-5-5-high-sidekick-swe-2-medium rated it medium, medium-high confidence: the refactor is small and CI-verified, but it defines new user-visible init semantics (return type depends on the lowering, save_idxs dropped, solve! gives an ODESolution) that a maintainer should decide on, and it partly misdescribes them.
• Merge: needs human review. Findings: init returns a different type depending on the lowering (integrator vs. finished solution); the solve!(init(...)) == solve(...) claim is false; save_idxs is silently dropped in the non-SCC init path; the behaviour change isn't disclosed; comments are over the guideline, and the test comment is retrospective; the PR is still a draft marked "ignore until reviewed".

Links

• PR: Add __init for DynamicSS/SICNM so init() doesn't fall through to NonlinearSolve's default #173
• Head Core (Julia 1) job: https://github.com/SciML/SteadyStateDiffEq.jl/actions/runs/35939086988/job/107446159527
• Head Core (Julia pre) job, which skipped build and test: https://github.com/SciML/SteadyStateDiffEq.jl/actions/runs/35939086988/job/107446159514
• Master commit: d81bcf1
• Original downstream failure: https://github.com/SciML/SciMLBase.jl/actions/runs/35839187919

---

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Conversation: local, non-interactive run; output at /out-SteadyStateDiffEq.jl-173.md (no session URL)

---

Adopted 2026-10-07 (ci-green head)

What changed

• Rebased onto master 735cb01; the original two commits keep their authorship.
• b7e82b4: comment trims and save_idxs handling for the plain-problem init path.
• aabe095 addresses the Codex gpt-6-astra CHANGES review (round 1):
  • init(prob, ::DynamicSS/SICNM) now returns a cache, not the raw ODE integrator. SteadyStateODECache holds the integrator and the setup (including the termination cache). solve! runs the same finalization as solve (termination_condition_result retcode mapping, best-state selection, residual, save_idxs) and returns the same SteadyStateSolution. step!(cache) advances the integrator, which is available as cache.integrator.
  • With an SCCNonlinearProblem lowering, init returns a SteadyStateSCCCache. Its solve! runs the sequential SCC solve with the requested algorithm and keywords. Before this change, init returned a finished solution, and solve! on it raised a MethodError.
  • __solve and solve! share __steady_state_solution and __solve_scc_lowering. __scc_lowering(prob) is factored out so the lowering is built once.
  • docs/src/index.md gains a section "Initialization and stepping". It documents the cache contract, including SICNM's extended [y; z] integrator state.
• This supersedes the correction in the earlier adoption note: solve!(init(prob, alg; kw...)) now matches solve(prob, alg; kw...) on retcode, u and resid. The new tests check this for every case.

Verification (Julia 1.12.4; MTK 11.45.3, NonlinearSolve 4.32.0, SciMLBase#1624 dev'd, same scratch environment as the review)

• New testset init/solve! on DynamicSS/SICNM matches solve in test/scc.jl covers plain problems, save_idxs, step!, finite-time nonconvergence (tspan = 1e-3), protective AbsNormSafeTerminationMode → Unstable, a manual SCC lowering (including save_idxs and a failing block), and an MTK SCC decomposition, for both DynamicSS and SICNM.
• Fail-before (b7e82b4 src with the new test file): scc | Pass 415 Fail 17 Error 24 Total 456. Representative failures:
  • Evaluated: ReturnCode.Success == ReturnCode.Failure: finite tspan.
  • ReturnCode.Terminated == ReturnCode.Unstable: protective termination.
  • MethodError: no method matching solve!(::NonlinearSolution{…SCCNonlinearProblem…}): SCC lowering.
• Pass-after (aabe095): scc | Pass 504 Total 504.
• GROUP=Core (official test/runtests.jl), exit 0: core.jl 2322/2322, developer_interfaces.jl 5/5, precompile_workload.jl 8/8, scc.jl 504/504, sicnm.jl 33/33. autodiff.jl has 0 assertions, the same as on master.
• test/qa/qa.jl: Quality Assurance 21/21, Reexport surface 16/16.
• The reviewer's probes.jl (adapted to the solution-return contract) and safe-probe.jl now give FINITE DynamicSS/SICNM direct=Failure staged=Failure, SAFE direct=Unstable staged=Unstable, and SCC … type=SteadyStateSCCCache, with solve! succeeding with retcode=Success.
• Runic --check and typos are clean on all changed files. The docs build (docs/make.jl) exits 0.

Not verified locally: Julia lts, pre and x86, downgrade, and a run against registered SciMLBase without #1624. CI covers these. CI on the previous head b7e82b4 was green on all checks with registered SciMLBase.

Red checks: CI on b7e82b4 and on master 735cb01 is all green. Checks for aabe095 are pending.

Stacked PR #177 needs a rebase onto this head. src/solve.jl merges cleanly. The using lines in src/SteadyStateDiffEq.jl and test/scc.jl conflict, and so does the tail of the MTK init testset. The conflicts are mechanical: keep both import sets, and append #177's new testset after this one.

Risk assessment

• Risk: medium
• Blast radius: init(::SteadyStateProblem, ::DynamicSS/SICNM) and solve!/step! on its result. init now returns a SteadyStateDiffEq cache (SteadyStateODECache or SteadyStateSCCCache), never a raw integrator or a finished solution, and solve! returns the same SteadyStateSolution as solve. solve keeps its ODE call, and its result building moved into the shared helper unchanged; all 2322 core.jl assertions and the existing scc.jl assertions pass. No new dependencies; solve! and step! are imported from SciMLBase like solve and init.
• Evidence: fail-before/pass-after above (415/17F/24E → 504/504); Core, QA and docs pass locally.
• Independent review: pending. Round 1 of Codex gpt-6-astra returned CHANGES with two P1 findings, both addressed here.
• Merge: needs human review. This adds new user-visible init semantics: the cache types, and cache.integrator as documented.

Please ignore until reviewed by @ChrisRackauckas.

🤖 Generated with Claude Code (model: claude-opus-5-5[1m]) https://claude.ai/code/session_011aK5Xvp9NpdkzKuEwtiMGd

🤖 Automated review section from an AI agent running as Chris Rackauckas's account — not written or reviewed by Chris.

Fresh independent review of aabe095

CHANGES/highH1. New SteadyStateODECache wrapper removes working non-SCC public interfaces: DynamicSS/SICNM symbolic indexing, state_values, parameter_values, getsym and reinit! each error. Dependency-matched clean current base passes14/14; head2pass12errors. Preserve wrapper interfaces and reset extended state/termination caches during reinitialization; commit discriminating regressions and reconcile sibling176 semantics. Intended SCC fix independently fails2cases before and passes6checks after; Core2322/developer5/precompile8/SCC504/SICNM33/QA37/docs positive do not cover wrapper regressions. Analytic ForwardDiff sensitivity8/8 passes. Unchanged large autodiff file has0assertions and returnsFailure on both head and clean base at t367.735; separate baseline investigation queued, not a new PR regression or proof of derivative accuracy. Rewrite stale original description around final cache contract. Full downstream/merged siblings/LTS not locally tested; exact historical generic Sonnet identity remains unverified.

Risk assessment

• Risk: high (H1).
• Blast radius: the affected solver/test/benchmark entrypoints described above; no additional coverage is inferred.
• Evidence: separate reviewer executions and negative controls described above; limitations retained.
• Independent review: Codex CLI 0.163.0 (gpt-6.1-sol), local session 01a1567e-fe58-7ff3-9e45-16bb3f972a14 (no session URL), rated it high (H1), high confidence in the observed findings; VERDICT: CHANGES at head aabe095.
• Merge: needs human review for medium/high; otherwise hold until findings and live gates are resolved.

Links:

• Pull request: Add __init for DynamicSS/SICNM so init() doesn't fall through to NonlinearSolve's default #173
• Reviewed head: aabe095

---

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🤖 Automated review section from an AI agent running as Chris Rackauckas's account — not written or reviewed by Chris.

Assigned correction of aabe095

This correction is queued to a fresh Codex CLI worker, model gpt-6.1-sol, under the SciML submaster’s pipeline ownership. Scope: Fresh CHANGES/H1: wrapper removes base-working non-SCC symbolic indexing/state_values/parameter_values/getsym/reinit; current-base14/14 versushead2pass12errors. Preserve both DynamicSS/SICNM interfaces and reset extended/termination state. Read sibling176/177; do not rescope them. Baseline AD fixture is separate.

The revision must preserve existing assertions and demonstrate the concrete failing-before/passing-after behavior using independent references. Default-branch failures, API or compatibility-policy decisions, and unavailable hardware remain separate findings. No test suppression, unvalidated push or unrelated repair.

The worker does not merge, approve or close PRs. Any pushed revision needs a fresh independent counted review; existing source reviews are not silently repinned. This assignment does not change the PR’s risk level or resolve any finding.

Links:

• Pull request: Add __init for DynamicSS/SICNM so init() doesn't fall through to NonlinearSolve's default #173

---

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🤖 Automated review section from an AI agent running as Chris Rackauckas's account — not written or reviewed by Chris.

Fix by Codex gpt-6.1-sol (head e08daab)

The non-SCC DynamicSS/SICNM cache provides symbolic state indexing, getsym, state_values, parameter_values, and the steady-state time provider. SICNM state access exposes only the steady-state variables, including when save_idxs slices the solution. reinit! rebuilds the integrator and termination setup using the new initial state and parameters, recomputes SICNM's Newton direction, and retains initialization options. The rendered documentation describes this contract and the new integrator instance after a reset. init returns a cache and solve! returns the finalized steady-state solution; SCC solving and sibling initialization/state-mapping work remain separate.

Executed validation

Julia 1.12.4; one Julia process at a time; four Julia threads, BLAS/OMP one thread, precompile tasks one, automatic precompilation off. All writable environments, temporary files, and the depot overlay were job-local. In the commands below, $RUNNER is the executed wrapper for timeout 3600 "$J" --compiled-modules=existing --check-bounds=yes; the environment and probe variables identify the isolated resolved environments and analytic sensitivity script.

The identical official regression file was run against an untouched archive of head aabe095a88153e7a0bfc0a87ad43ce0140f5a139 and the corrected source, with matched dependency manifests differing only in the developed package path:

"$RUNNER" -O0 --project="$UNFIXEDENV" test/cache_interface.jl
GROUP=Core "$RUNNER" -O0 --project="$TESTENV" test/runtests.jl

Unfixed source: exit 1, with wrapper MethodErrors:

ERROR: LoadError: Some tests did not pass: 42 passed, 0 failed, 108 errored, 0 broken.
initialized cache interfaces and reset      |   42    108    150  1m35.8s

Corrected source, full official Core group: exit 0:

Core/autodiff.jl |     0  4m53.7s
Core/cache_interface.jl |  372    372  1m03.7s
Core/core.jl  | 2322   2322  52.3s
Core/developer_interfaces.jl |    5      5  0.2s
Core/precompile_workload.jl |    8      8  2.9s
Core/scc.jl   |  504    504  2m24.9s
Core/sicnm.jl |   33     33  30.6s

The default-branch interface control was also executed on clean default commit 471a4a039f637459ff8625cc832f20a7b85f4f49: the reviewer's cache-probe.jl passes 14/14 with both algorithms. Current PR checks were all successful before this push, so there were no failed CI logs to repair; gh run view --log-failed returned no output. Recent default CI runs inspected were successful.

GROUP=QA "$RUNNER" -O0 --project="$TESTENV" test/runtests.jl
"$RUNNER" -O0 --project="$DOCSENV" docs/make.jl
"$RUNNER" -O0 --project="$TESTENV" "$SENSITIVITY_PROBE"

All exit 0. QA output:

QA/qa.jl      |   37     37  2m41.8s

Docs output:

[ Info: CheckDocument: running document checks.
[ Info: Populate: populating indices.
[ Info: RenderDocument: rendering document.
[ Info: HTMLWriter: rendering HTML pages.

Docs emitted dependency world-age warnings and the local skipped-deployment warning. The analytic 0 = p - u probe independently checks du/dp = 1 for direct and staged solves:

SENSITIVITY DynamicSS staged=false derivative=0.9999999999240353
SENSITIVITY DynamicSS staged=true derivative=0.9999999999240353
SENSITIVITY SICNM staged=false derivative=0.9999999999986849
SENSITIVITY SICNM staged=true derivative=0.9999999999986849
Test Summary:                                                | Pass  Total   Time
analytic sensitivity of direct and staged steady-state solve |    8      8  14.8s

"$RUNNER" -O0 --project="$RUNICENV" -m Runic --check src/SteadyStateDiffEq.jl src/solve.jl test/cache_interface.jl docs/make.jl
typos src/SteadyStateDiffEq.jl src/solve.jl test/cache_interface.jl docs/make.jl docs/src/index.md
git diff --check aabe095a88153e7a0bfc0a87ad43ce0140f5a139..HEAD

All exit 0 with no diagnostic output. Runic formatting was also applied in the job-local formatter environment before these checks. No dependency, exported name, existing assertion, skip, broken marker, tolerance, or warning policy changed.

G1: analytic roots source/rate and independently evaluated residuals, plus the analytic derivative above. G2: actual in-place/out-of-place cache paths, both algorithms, stored/callable non-SCC lowerings, stepping, and the ForwardDiff direct/staged paths. G3: repeated initial-state/parameter resets, SICNM's consistent extended initial state, safe-best termination, full-state access with solution slicing, and retention of earlier solution and original problem values.

Fixture control: the initial safe-best Tsit5 case returned Stalled in both a fresh solve and a reset solve with identical state 3.0000000000673706. An independent Rodas5P control returned Success in both paths at 3.0000000000281273. Safe-best reset coverage uses Rodas5P; default-mode reset coverage retains Tsit5. The success, root, and residual assertions remain intact.

Not verified: the full SciMLBase downstream symbolic-indexing group, merged sibling branches, LTS/pre/32-bit/minimum-compatibility matrices, or GPU paths. The inherited large AD file has zero assertions and emits its solver warning; it is unchanged and is separate from the analytic sensitivity evidence. Remote CI was checked once after the push: eight jobs were in progress. No CI rerun wave, merge, approval, release, or history rewrite was performed. API/release disposition and a new independent risk rating remain with the owning review chain.

Next counted review must come from a smart model in a fresh session, not this fix session (risk.md § Independent reviews).

Links:

• Pull request: Add __init for DynamicSS/SICNM so init() doesn't fall through to NonlinearSolve's default #173
• Corrected head: ChrisRackauckas-Claude@e08daab
• Default control: 471a4a0

---

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🤖 Automated review section from an AI agent running as Chris Rackauckas's account — not written or reviewed by Chris.

Independent review of head e08daab

Documented reinit keyword overrides fail when concrete cache fields change type; prior higher high/H1 assessment is retained for the merge decision.

Support unsliced→sliced and sliced→unsliced cache resets, introducing an ODE option such as dt, and changing termination mode for both DynamicSS and SICNM. The current concrete-field assignments throw conversion errors after partial mutation. Add discriminating official regressions and update cache state consistently; retain every existing assertion.

Other Julia versions and the sibling combined stack remain unverified. Tsit5 safe-best return-code failures reproduce in default controls; they are not attributed to this cache change. The earlier high/H1 assessment remains conservative pending correction.

Risk assessment

• Risk: medium (M1).
• Blast radius: Documented reinit keyword overrides fail when concrete cache fields change type; prior higher high/H1 assessment is retained for the merge decision.
• Evidence: Reviewer ran official Core:3244 assertions, QA37/37 and unchanged warm docs:pass. Identical cache-interface test gives42passes/108errors on unfixed code and372/372 on this head. Independent4/4ForwardDiff checks and48 matched default/unfixed/head numerical controls pass. New override probes reproduce the conversion failures; the existing372 assertions miss changes of field type.
• Independent review: Codex CLI0.163.0 (gpt-6.1-sol), local session 01a15c04-7718-73c0-a27a-d9238d6cb26f (no session URL), rated it medium (M1); VERDICT:CHANGES at head e08daab. Fresh session distinct from the author; original body and historical ratings were not read.
• Merge: Needs changes or verification; medium/high and permission/license decisions remain with Chris through the master.

Links:

• Pull request: Add __init for DynamicSS/SICNM so init() doesn't fall through to NonlinearSolve's default #173

---

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🤖 Automated review section from an AI agent running as Chris Rackauckas's account — not written or reviewed by Chris.

Fix by Codex gpt-6.1-sol (head 553252a)

Addresses the option-override blocker at e08daab7b8f9fdb30986561719069f89160e2869. Rebuilt problem/integrator/setup/slicing/options are installed through one replaceable state reference, allowing their concrete types to change. reinit! returns the same cache object and commits that state only after initialization succeeds. Readers use one state snapshot when they need related components. The seven-argument constructor and logical properties remain available. The docstring/manual retain type-changing overrides and describe failed-rebuild behavior.

The original cache_interface.jl, including all 372 assertions and safe-best fixtures, is byte-identical to e08daab. The new official cache_reinit_options.jl covers adding/removing slicing, introducing dt=0.01, changing to safe-best termination and back, retaining options across resets, symbolic/full SICNM state, retained outputs/inputs, failed rebuilds, and subsequent reuse.

Executed validation

Julia 1.12.4; one top-level Julia command at a time; four Julia threads; BLAS/MKL/OMP/BLIS and precompile tasks one; automatic precompilation off. Budget gates passed before work and publication. Resource guards before each Julia command checked home availability ≥200 GiB, available memory ≥40 GiB, and load ≤96. All observed checks passed. Environments, writable depot overlays and temporary files were job-local. $RUNNER invokes timeout 3600 "$J" --compiled-modules=existing --check-bounds=yes; environment/probe variables below name the isolated job-local artifacts.

The exact frozen new test file was run against an untouched archive of e08daab and the fixed source. Dependency manifests differ only in the developed package path:

"$RUNNER" -O0 --project="$E08ENV" test/cache_reinit_options.jl
GROUP=Core "$RUNNER" -O0 --project="$TESTENV" test/runtests.jl

Before, exit 1 (conversion errors and inconsistent state after partial assignment):

ERROR: LoadError: Some tests did not pass: 234 passed, 21 failed, 29 errored, 0 broken.
type-changing steady-state cache reset options |  234    21     29    284  27.2s

After, full official Core group, exit 0:

Core/autodiff.jl |     0  5m01.1s
Core/cache_interface.jl |  372    372  1m02.7s
Core/cache_reinit_options.jl |  284    284  15.3s
Core/core.jl  | 2322   2322  52.3s
Core/developer_interfaces.jl |    5      5  0.2s
Core/precompile_workload.jl |    8      8  3.1s
Core/scc.jl   |  504    504  2m29.5s
Core/sicnm.jl |   33     33  31.9s

GROUP=QA "$RUNNER" -O0 --project="$TESTENV" test/runtests.jl
"$RUNNER" -O0 --project="$DOCSENV" docs/make.jl
"$RUNNER" -O0 --project="$TESTENV" "$CONSTRUCTOR_PROBE"
"$RUNNER" -O0 --project="$TESTENV" "$SENSITIVITY_PROBE"

All exit 0. QA and separate seven-argument construction/retained-state probe:

QA/qa.jl      |   37     37  2m03.4s
seven-argument cache constructor integration |   16     16  12.1s

Docs completed doctests, document checks and HTML rendering. Dependency world-age warnings and the local skipped-deployment warning were emitted; warning policies and assertions were unchanged. Tail:

[ Info: CheckDocument: running document checks.
[ Info: Populate: populating indices.
[ Info: RenderDocument: rendering document.
[ Info: HTMLWriter: rendering HTML pages.

Independent analytic 0=p-u, du/dp=1 probe:

SENSITIVITY DynamicSS staged=false derivative=0.9999999999240353
SENSITIVITY DynamicSS staged=true derivative=0.9999999999240353
SENSITIVITY SICNM staged=false derivative=0.9999999999986849
SENSITIVITY SICNM staged=true derivative=0.9999999999986849
Test Summary:                                                | Pass  Total   Time
analytic sensitivity of direct and staged steady-state solve |    8      8  16.6s

"$RUNNER" -O0 --project="$RUNICENV" -m Runic --check src/solve.jl test/cache_reinit_options.jl
typos src/solve.jl test/cache_reinit_options.jl docs/src/index.md
git diff --check e08daab7b8f9fdb30986561719069f89160e2869..HEAD

All exit 0, with no formatter/spelling/diff diagnostics. Formatting was applied in the local formatter environment before freezing the source and tests. Official groups ran directly through test/runtests.jl; no parallel runner was introduced. No existing assertion, tolerance, fixture, dependency, export, version, or warning policy changed.

G1: independent roots u=p, residual zero and consistent SICNM direction z=p-u0, plus the analytic derivative. G2: both algorithms, every requested override transition, stepping, retained options, and direct/staged ForwardDiff paths. G3: unchanged cache identity, coherent failed-rebuild state, preserved earlier outputs and inputs, subsequent reuse and separate seven-argument construction.

Return codes in the new repeated-reset check are compared with a fresh solve at the same operating point, alongside independent analytic root assertions. A fresh solve on published e08daab with Rodas5P, u0=[-2,-3], p=[6,7] returns Stalled, with residual components [1.1093970186948354e-10, 1.3867929027355785e-10] above the requested absolute threshold 1e-10. This numerical stopping behavior is separate from cache option storage; it was not changed. Return-code parity checks that the requested termination mode is honored rather than silently ignored. The existing 372 assertions were not weakened.

Remaining integration and review limits

The inspected sibling state-mapping diff still contains five-argument cache construction. The separate 16/16 probe checks the retained seven-argument contract; it is not a claim that the sibling tree was merged or validated. That branch's constructor update and combined-stack validation remain separate work. No sibling source was merged or changed here.

The original higher high/H1 assessment remains in force. A new independent review is required, and API/version/release disposition remains with the owning review chain. No self-authored counted review or risk downgrade is supplied.

At intake, Core/QA/docs/format/spelling/downgrade checks were successful. A separate Dependabot workflow had startup_failure with zero jobs at e08daab; its log request returned not found. No test-job failure was available to repair or compare, and no default parity is claimed for that startup failure. Recent default runs inspected were successful. The inherited large AD fixture still has zero assertions and its solver warning; it is unchanged and separate from the sensitivity probe.

Not verified locally: the combined sibling tree, full downstream symbolic indexing, LTS/pre/32-bit/minimum-compatibility matrices, GPU paths, or completed new CI. One normal append-only push was made; the post-push check showed six jobs queued. No force push, rebase, rerun wave, merge, approval, closure, settings change or release.

Next counted review must come from a smart model in a fresh session, not this fix session (risk.md § Independent reviews).

Links:

• Pull request: Add __init for DynamicSS/SICNM so init() doesn't fall through to NonlinearSolve's default #173
• Corrected head: ChrisRackauckas-Claude@553252a
• Original reviewed head: e08daab
• Separate state-mapping sibling: Map SCC-lowered steady-state solutions back onto the problem's state (stacked on #173) #177
• Default CI inspected: https://github.com/SciML/SteadyStateDiffEq.jl/actions/runs/39437145810
• Separate startup failure: https://github.com/SciML/SteadyStateDiffEq.jl/actions/runs/39378737766

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Independent review of head 85dfcd0

VERDICT: CHANGES
RISK: high (H1)
SUMMARY: The SCC initialization fix works, but the new cache wrapper removes working symbolic parameter access and state assignment.

Findings

1. src/solve.jl:183 and src/solve.jl:205 — blocking: Preserve the existing symbolic parameter proxy and state assignment interfaces. On the merge-base, init(prob, DynamicSS(Tsit5())) and init(prob, SICNM(Rodas5P())) return caches supporting cache.ps[:a], cache.ps[:a] = value, and cache[:x] = value. The new getproperty forwards :ps to a named tuple with no such field, and the wrapper implements getindex without setindex!. This breaks previously working callers even though read-only cache[:x], getsym, and reset tests pass. Preserve these operations with the appropriate solver/extended-state bookkeeping and commit regression coverage for both algorithms. The unchanged 2.18.0 version does not identify a breaking release.

2. PR body — nit: Consolidate the description around the final implementation. The original Fix/Verification sections still describe a raw integrator for ordinary problems and an eagerly computed solution for SCC problems, whereas this head returns SteadyStateODECache/SteadyStateSCCCache. Later adoption notes supersede those statements, but leave mutually incompatible descriptions in the main body.

Evidence

Independent review by Codex, model gpt-6.1-sol. Reviewed head 85dfcd0f2edda347fc1fcf5851592392fba6912e; merge-base 735cb010cdf47ac93cb7def5bffda8d96dfdada7.

1. Intended fix, fail-before/pass-after. Same analytic 4-u²=0 SCC fixture and script on both trees:
   Base output (exit 1 because the intended-fix test fails):

   SCC DynamicSS ERROR FieldError: type SCCNonlinearProblem has no field `u0`
   SCC SICNM ERROR FieldError: type SCCNonlinearProblem has no field `u0`
   Test Summary:                | Fail  Total  Time
   requested SCC init algorithm |    2      2  3.0s
   

   Head output (exit 0):

   SCC DynamicSS cache=SteadyStateSCCCache retcode=Success u=[1.9999999999915248]
   SCC SICNM cache=SteadyStateSCCCache retcode=Success u=[2.000000000024193]
   Test Summary:                | Pass  Total   Time
   requested SCC init algorithm |    4      4  16.4s
   

2. Blocking symbolic-interface regression (finding 1), pass-before/fail-after:
   Base output (exit 0, 6/6 pass on base-working mutable symbolic interfaces).
   Head output (exit 1 because the six compatibility checks fail; the subsequent official SCC testsets all pass 504/504):

   CACHE DynamicSS SteadyStateODECache
   read_parameter_proxy ERROR FieldError: type NamedTuple has no field `ps`
   write_parameter_proxy ERROR FieldError: type NamedTuple has no field `ps`
   write_state_index ERROR MethodError: no method matching setindex!(::SteadyStateDiffEq.SteadyStateODECache{DynamicSS{...}, Tuple{}}, ::Float64, ::Symbol)
   CACHE SICNM SteadyStateODECache
   read_parameter_proxy ERROR FieldError: type NamedTuple has no field `ps`
   write_parameter_proxy ERROR FieldError: type NamedTuple has no field `ps`
   write_state_index ERROR MethodError: no method matching setindex!(::SteadyStateDiffEq.SteadyStateODECache{SICNM{...}, Tuple{}}, ::Float64, ::Symbol)
   Test Summary:                            | Fail  Total   Time
   base-working mutable symbolic interfaces |    6      6  13.7s
   

Risk assessment

• Risk: high (H1) — the wrapper rejects previously working symbolic proxy/assignment operations (cache.ps[:a], cache.ps[:a] = value, cache[:x] = value), reaching ordinary non-SCC initialized DynamicSS and SICNM users.
• Blast radius: SteadyStateODECache symbolic indexing and parameter proxy access in src/solve.jl.
• Evidence: fail-before/pass-after SCC initialization controls (4/4), base-pass/head-fail mutable symbolic interface controls (6/6), and 1,160 passing PR test assertions on Julia 1.12.7.
• Independent review: Codex CLI (gpt-6.1-sol), local job oss-reviews-2026-10-21-SciML-SteadyStateDiffEq-173 (no session URL), rated high (H1), high confidence, verdict CHANGES at head 85dfcd0.
• Merge: blocked — fix the blocking symbolic parameter proxy and state assignment regression first.

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Fix by Cursor auto (head 439c8c5)

Restores the merge-base symbolic parameter proxy and state assignment interfaces on SteadyStateODECache for DynamicSS and SICNM.

• cache.ps returns SymbolicIndexingInterface.ParameterIndexingProxy(cache); :ps is included in propertynames.
• cache[sym] = value uses setu and marks the integrator modified via SciMLBase.derivative_discontinuity! (the current name of the review's u_modified! notify).
• SICNM residual g now takes live parameters from the integrator. After cache[:x] = value or cache.ps[:a] = value, the algebraic direction is recomputed as z = -J(y)⁻¹ g(y) and refreshed again before step!/solve! when the integrator is marked modified.
• Official regressions in test/cache_interface.jl cover both DynamicSS(Tsit5()) and SICNM(Rodas5P()) (iip and oop): cache.ps[:a], cache.ps[:a] = value, cache[:x], cache[:x] = value, SICNM consistent z, and solve! reflecting the mutated operating point. No @inferred on getu(prob, :x)(cache).

The original PR Fix/Verification text still describes an earlier integrator/eager-solution contract. Later adoption notes and this section describe the current cache types; the original body was not rewritten here.

Fail-before / pass-after (interface probe)

Unfixed head 85dfcd0 (6/6 fail):

CACHE DynamicSS SteadyStateODECache
read_parameter_proxy ERROR FieldError: type NamedTuple has no field `ps`
write_parameter_proxy ERROR FieldError: type NamedTuple has no field `ps`
write_state_index ERROR MethodError: no method matching setindex!(::SteadyStateODECache, ::Float64, ::Symbol)
CACHE SICNM SteadyStateODECache
read_parameter_proxy ERROR FieldError: type NamedTuple has no field `ps`
write_parameter_proxy ERROR FieldError: type NamedTuple has no field `ps`
write_state_index ERROR MethodError: no method matching setindex!(::SteadyStateODECache, ::Float64, ::Symbol)
Test Summary:                            | Fail  Total  Time
base-working mutable symbolic interfaces |    6      6  10.8s

After this commit (6/6 pass):

CACHE DynamicSS SteadyStateODECache
read_parameter_proxy 2.0
write_parameter_proxy 6.0
write_state_index 1.0
CACHE SICNM SteadyStateODECache
read_parameter_proxy 2.0
write_parameter_proxy 6.0
write_state_index 1.0
Test Summary:                            | Pass  Total  Time
base-working mutable symbolic interfaces |    6      6   9.7s

Executed validation

julia --project=@runic -m Runic --inplace src/solve.jl src/SteadyStateDiffEq.jl test/cache_interface.jl docs/src/index.md
julia --project=@runic -m Runic --check src/solve.jl src/SteadyStateDiffEq.jl test/cache_interface.jl docs/src/index.md
typos src/solve.jl src/SteadyStateDiffEq.jl test/cache_interface.jl docs/src/index.md
GROUP=Core julia --project -e 'using Pkg; Pkg.test()'
GROUP=QA julia --project -e 'using Pkg; Pkg.test()'
julia --project=docs -e 'using Pkg; Pkg.develop(path="."); Pkg.instantiate(); include("docs/make.jl")'

Runic --check and typos exited 0 with no diagnostics.

Official Core (Julia 1.12.4), exit 0:

Core/autodiff.jl |     0  1m04.0s
Core/cache_interface.jl |  434    434  3m19.8s
Core/cache_reinit_options.jl |  284    284  31.8s
Core/core.jl  | 2322   2322  1m15.0s
Core/developer_interfaces.jl |    5      5  0.3s
Core/precompile_workload.jl |    8      8  5.1s
Core/scc.jl   |  504    504  4m57.5s
Core/sicnm.jl |   33     33  1m15.7s
     Testing SteadyStateDiffEq tests passed

Official QA: Aqua, ExplicitImports (6/6 after accessing ParameterIndexingProxy from SymbolicIndexingInterface), public-API docs, and reexports passed. JET mode=typo threw IOError: FolderMonitor (start): too many open files (EMFILE) on two isolated retries under host file-watcher load. That is not a code finding; CI QA on the previous head was already green.

Docs completed doctests, document checks, and HTML rendering:

[ Info: CheckDocument: running document checks.
[ Info: Populate: populating indices.
[ Info: RenderDocument: rendering document.
[ Info: HTMLWriter: rendering HTML pages.

No existing assertion, skip, broken marker, or warning policy was changed. No @inferred was added on getu(prob, :x)(cache).

Next counted review must come from a smart model in a fresh session, not this fix session (risk.md § Independent reviews).

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Risk assessment (independent review, Codex CLI (gpt-6.1-sol), local job oss-reviews-2026-10-21-SciML-SteadyStateDiffEq-jl-173 (no session URL), head 439c8c5)

• Risk: high (H1)
• Blast radius: reviewed diff at head 439c8c5 (src/solve.jl)
• Evidence: executed independent controls below
• Independent review: Codex CLI (gpt-6.1-sol) independently reviewed this PR at head 439c8c5078c0 and rated it high (H1), high confidence, verdict CHANGES.
• Merge: review blocks (reinit! keyword u0 compatibility regression)

Executed review notes (head 439c8c5)

VERDICT: CHANGES
RISK: high (H1)
SUMMARY: SCC initialization is fixed, but the new cache breaks keyword-based reinitialization and can reuse a stale initial state.

Findings

1. src/solve.jl:279 — blocking: Preserve the existing reinit!(cache; u0=..., p=...) interface. The new method only consumes positional u0; keyword u0 lands in kwargs, bypasses remake, and reaches the ODE initializer. For SICNM, this replaces the extended [y; z] initial state with the caller's y vector and throws Mass matrix size is incompatible with initial condition sizing. For DynamicSS, the first keyword reset appears to work, but stores u0 among the persistent initialization options: after reinit!(cache; u0=[-3.0], p=[4.0]), a subsequent reinit!(cache, [7.0]; p=[8.0]) still starts at [-3.0]. The identical sequence passes on the merge-base for both algorithms. Consume and normalize keyword u0 before rebuilding the problem, keep it out of the stored ODE options, and add keyword-then-positional reset regressions for both algorithms. The PR's reset tests use positional u0, so they miss this compatibility regression. Retaining version 2.18.0 does not designate a breaking release; preserve the working interface.

2. pr.json:1 (body, original “Fix” and “Verification” sections) — nit: Rewrite the description around the final implementation. Those sections still promise a raw integrator for ordinary problems and an eagerly computed solution for SCC problems. The reviewed head returns SteadyStateODECache and SteadyStateSCCCache, respectively. Later appended corrections describe that contract, but leave contradictory claims in the main description.

Evidence

Independent review of head 439c8c5078c07e5aa002b037e309f756f990c0a2 against merge-base 735cb010cdf47ac93cb7def5bffda8d96dfdada7, using Julia 1.12.7. No edits, commits, pushes, or GitHub posts were made in/from repo.

Risk assessment: Before reading the PR body, the diff was provisionally medium (M1). The demonstrated compatibility regression raises it to high (H1), the highest matching criterion. Matching criteria: L1 (documentation), L2 (added assertions without weakening existing ones), L7 (shared setup/finalization refactor under 400 changed non-test source lines), ML8 (cache state/reset bookkeeping with tests), M1 (new methods on SciMLBase interfaces and changed init dispatch/return contract), and H1 (previously accepted reinitialization inputs now error or select the wrong initial state). The affected lane is non-SCC init/reinit! with DynamicSS or SICNM; the SCC initialization fix itself is independently reproduced.

Scratch trees were created with:

git -C repo archive HEAD | tar -x -C tmp/head
git -C repo archive 735cb010cdf47ac93cb7def5bffda8d96dfdada7 | tar -x -C tmp/base

Only scratch project metadata was expanded to include the existing test extras. After Pkg.resolve()/Pkg.instantiate(), the same Project.toml and Manifest.toml were used on both trees. Both loaded SciMLBase 3.58.0 and NonlinearSolve 4.32.0. The head source checksum matches the untouched checkout.

Intended fix, failing on base and passing on head:

JULIA_NUM_THREADS=4 timeout 2400 julia --project=tmp/base tmp/probes.jl > tmp/base-probes.log 2>&1
JULIA_NUM_THREADS=4 timeout 2400 julia --project=tmp/head tmp/probes.jl > tmp/head-probes.log 2>&1

The discriminating test initializes and solves an SCC lowering with residual 4 - u^2, initial state [1.0], and independent expected root [2.0].

Base, exit 1:

SCC DynamicSS ERROR FieldError: type SCCNonlinearProblem has no field `u0`
SCC SICNM ERROR FieldError: type SCCNonlinearProblem has no field `u0`
Test Summary:                | Fail  Total  Time
requested SCC initialization |    2      2  2.6s

Head, exit 0:

SCC DynamicSS cache=SteadyStateSCCCache ret=Success u=[1.9999999999915263]
SCC SICNM cache=SteadyStateSCCCache ret=Success u=[1.9999999999928297]
Test Summary:                | Pass  Total  Time
requested SCC initialization |    2      2  7.1s

Blocking regression, passing on base and failing on head:

JULIA_NUM_THREADS=4 timeout 2400 julia --project=tmp/base tmp/reset_regression.jl > tmp/base-reset.log 2>&1
JULIA_NUM_THREADS=4 timeout 2400 julia --project=tmp/head tmp/reset_regression.jl > tmp/head-reset.log 2>&1

The fixture is SteadyStateProblem((u,p,t)->p .- u, [0.0], [2.0]); each algorithm receives the same keyword reset to [-3.0], followed by the same positional reset to [7.0].

Base, exit 0:

DynamicSS keyword reset state=[-3.0]
DynamicSS positional reset state=[7.0]
SICNM keyword reset state=[-3.0]
SICNM positional reset state=[7.0]
Test Summary:                       | Pass  Total  Time
keyword then positional cache reset |    4      4  7.4s

Head, exit 1:

DynamicSS keyword reset state=[-3.0]
DynamicSS positional reset state=[-3.0]
DynamicSS: Test Failed
  Expression: state_values(cache) == [7.0]
   Evaluated: [-3.0] == [7.0]
SICNM: Error During Test
  Got exception outside of a @test
  Mass matrix size is incompatible with initial condition
  sizing. The mass matrix must represent the `vec`
  form of the initial condition `u0`, i.e.
Test Summary:                       | Pass  Fail  Error  Total   Time
keyword then positional cache reset |    1     1      1      3  10.9s

Independent derivative checks:

JULIA_NUM_THREADS=4 timeout 2400 julia --project=tmp/head tmp/followup.jl > tmp/head-followup.log 2>&1
JULIA_NUM_THREADS=4 timeout 2400 julia --project=tmp/base tmp/followup.jl > tmp/base-followup.log 2>&1

For f(u,p)=p[1]-2u, the analytic steady state is p[1]/2 and its derivative is 0.5. All eight explicit derivative assertions pass on each tree: both algorithms, in-place/out-of-place, direct solve/staged solve!(init(...)). Head output:

DynamicSS AD staged=false iip=false => 0.499999999990248
DynamicSS AD staged=false iip=true => 0.4999999999904638
DynamicSS AD staged=true iip=false => 0.499999999990248
DynamicSS AD staged=true iip=true => 0.4999999999904638
SICNM AD staged=false iip=false => 0.5000000000003417
SICNM AD staged=false iip=true => 0.5000000000003444
SICNM AD staged=true iip=false => 0.5000000000003417
SICNM AD staged=true iip=true => 0.5000000000003444

The head follow-up process exits 1 because its subsequent keyword-reset test reproduces finding 1; the base follow-up exits 0. The exploratory probes also exposed scalar-assignment and post-termination mutation limitations on the base, which are not counted as introduced regressions.

Official Core runner, exit 0, 3,590 assertions pass:

JULIA_NUM_THREADS=4 GROUP=Core timeout 2400 julia --project=tmp/head tmp/head/test/runtests.jl > tmp/core.log 2>&1

Test Summary:    | Total     Time
Core/autodiff.jl |     0  1m12.8s
Test Summary:           | Pass  Total     Time
Core/cache_interface.jl |  434    434  1m35.6s
Test Summary:                | Pass  Total   Time
Core/cache_reinit_options.jl |  284    284  22.6s
Test Summary: | Pass  Total   Time
Core/core.jl  | 2322   2322  45.8s
Test Summary:                | Pass  Total  Time
Core/developer_interfaces.jl |    5      5  0.2s
Test Summary:               | Pass  Total  Time
Core/precompile_workload.jl |    8      8  3.2s
Test Summary: | Pass  Total     Time
Core/scc.jl   |  504    504  3m12.2s
Test Summary: | Pass  Total   Time
Core/sicnm.jl |   33     33  45.4s

The unchanged autodiff.jl fixture logs a NaN error estimate and aborts integration at t=367.7350295054817, while its zero-assertion testset remains green. This also occurs on the base; it is not an introduced regression. Independent baseline check, exit 0:

JULIA_NUM_THREADS=4 timeout 2400 julia --project=tmp/base -e 'include("tmp/base/test/autodiff.jl"); println("BASE_AD_RETCODE=", sol.retcode); println("BASE_AD_TEST_ASSERTIONS=0")' > tmp/base-autodiff.log 2>&1

Relevant real output:

│   step error estimate EEst = NaN (a step is accepted when EEst <= 1)
BASE_AD_RETCODE=Failure

Static/CI checks: git -C repo diff --numstat <base> HEAD shows no dependency, compat, version, or license changes. All imported packages were already dependencies; the package retains its MIT license. Existing assertions/tolerances/skips are preserved. The new tests include analytic equilibrium/residual checks rather than relying solely on equality between two paths sharing implementation. The supplied pr.json reports 13 checks, all SUCCESS, including Core, QA, docs, downgrade, and benchmarks; this is supplied CI metadata, not a local rerun of each job. test/autodiff.jl still has no assertions, as on base, so its successful execution alone does not demonstrate derivative accuracy.

Not verified

• Full SciMLBase downstream SymbolicIndexingInterface environment, merged sibling PRs, or downstream packages beyond the independent reproducer.
• Local Julia LTS/prerelease/x86, downgrade, QA/JET, documentation build, or performance benchmarks; supplied CI metadata covers those named jobs but was not independently audited job-by-job.
• General AD coverage beyond the eight analytic ForwardDiff checks; no new GPU/MPI/AD-rule extension is introduced by this diff.

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