refactor(stm): refactor error handling from Midnight library

[hjeljeli32]

Content

Typed StmCircuitError guard failures raised in the non-recursive (certificate) circuit's Relation::circuit implementation were flattened into plonk::Error::Synthesis(String) at the relation boundary (via to_synthesis_error), losing the error type and forcing callers and tests to rely on fragile string matching. Midnight zk 2.3.3 lets a relation surface its own error type end-to-end through the Relation::Error associated type (midnightntwrk/midnight-zk#248).

This types the certificate circuit's error boundary: the circuit returns StmCircuitError directly, the flattening adapter is removed, and the negative tests assert typed variants. The change is confined to the non-recursive circuit (circuits/halo2/).

Changes

• Typed relation error: StmCertificateCircuit::Error is now StmCircuitError (was plonk::Error). A Backend(String) catch-all variant and a From<plonk::Error> conversion satisfy Midnight's new Relation::Error: From<plonk::Error> bound; backend/library errors convert into it while the circuit's own domain guards stay fully typed.
• Removed the flattening adapter: to_synthesis_error is deleted for the non-recursive circuit. The relation (circuit.rs), witness assignment (witness_assignments.rs), and the gadget layer it feeds (merkle_path, comparison_helpers, comparison, lottery) now return StmCircuitError directly; standard-library plonk::Error values convert upward through From.
• Typed source preserved for callers: the prover path keeps StmCircuitError downcastable through the anyhow source chain, so callers and tests match on typed variants instead of parsing synthesis message text.
• Tests: removed the assert_proving_backend_message_contains string-matching helper; the six negative cases now assert exact StmCircuitError variants; the focused test-relation macro is parameterized by error type; and a From<plonk::Error> conversion unit test guards the trait contract.

Pre-submit checklist

• Branch
  • Tests are provided (if possible)
  • Crates versions are updated (if relevant)
  • CHANGELOG file is updated (if relevant)
  • Commit sequence broadly makes sense
  • Key commits have useful messages
• PR
  • All check jobs of the CI have succeeded
  • Self-reviewed the diff
  • Useful pull request description
  • Reviewer requested
• Documentation
  • No new TODOs introduced

Issue(s)

Closes #3382

[github-actions]

Test Results

     5 files  ± 0     209 suites  ±0   42m 30s ⏱️ - 18m 36s
 3 340 tests +31   3 340 ✅ +31  0 💤 ±0  0 ❌ ±0 
11 072 runs  +37  11 072 ✅ +37  0 💤 ±0  0 ❌ ±0 

Results for commit 976d808. ± Comparison against base commit a8b7c9c.

♻️ This comment has been updated with latest results.

[Copilot]

Pull request overview

This PR upgrades the midnight-* dependencies and refactors STM Halo2 circuit/proof plumbing to preserve typed circuit errors (StmCircuitError) across the Relation::circuit boundary (removing prior string-based synthesis error flattening). It also updates IVC fixed-base handling and regenerates/updates golden assets accordingly.

Changes:

• Upgrade midnight-circuits/curves/proofs/zk-stdlib and adapt call sites to new APIs (MidnightCircuit::from_relation(..., None), SRS downsizing, verifier params usage).
• Preserve typed StmCircuitError end-to-end in the non-recursive certificate circuit and update negative tests to assert on typed variants.
• Update IVC accumulator/fixed-base handling (prefix renames, removal of com_instance dummy entry, pre-flight MSM/fixed-base consistency check) and refresh related golden assets/tests.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
mithril-stm/src/protocol/aggregate_signature/clerk.rs	Adjust test setup to new MidnightCircuit/SRS downsizing API.
mithril-stm/src/protocol/aggregate_signature/ancillary_data.rs	Update expected digest constant to match regenerated assets/behavior.
mithril-stm/src/proof_system/ivc_halo2_snark/verifier_setup.rs	Remove tau_g2 storage/extraction; rely on verifier params and updated fixed-base prefixes.
mithril-stm/src/proof_system/ivc_halo2_snark/prover_setup.rs	Add MSM/fixed-base pre-flight checks; construct accumulators via from_dual_msm; update prefixes.
mithril-stm/src/proof_system/ivc_halo2_snark/prover_input_helpers.rs	Propagate new StmResult return from certificate_collapsed_accumulator.
mithril-stm/src/proof_system/ivc_halo2_snark/proof.rs	Update accumulator verification to use verifier params; adjust tests accordingly.
mithril-stm/src/proof_system/halo2_snark/setup.rs	Switch to MidnightCircuit::from_relation(..., None).k() and new SRS downsizing flow.
mithril-stm/src/proof_system/halo2_snark/proof.rs	Refresh golden proof/verifier-data fixtures; add ignored generator test helper.
mithril-stm/src/circuits/halo2/witness_assignments.rs	Return StmCircuitError from witness assignment helpers and propagate backend errors via From.
mithril-stm/src/circuits/halo2/tests/test_helpers.rs	Parameterize test harness over relation error type; update circuit degree derivation.
mithril-stm/src/circuits/halo2/tests/golden/helpers.rs	Remove backend string-matching helper; update proving error propagation and cost model calls.
mithril-stm/src/circuits/halo2/tests/golden/cases/negative.rs	Convert negative tests from string matching to typed StmCircuitError assertions.
mithril-stm/src/circuits/halo2/mod.rs	Update module docs to reflect backend error conversion (not synthesis flattening).
mithril-stm/src/circuits/halo2/keys.rs	Update circuit degree discovery and expose degree as u32; adapt keygen sizing.
mithril-stm/src/circuits/halo2/key_serialization.rs	Update test keygen path to new circuit degree/SRS handling.
mithril-stm/src/circuits/halo2/gadgets/unique_schnorr_signature.rs	Update focused test relation macro usage with explicit error type.
mithril-stm/src/circuits/halo2/gadgets/merkle_path.rs	Return StmCircuitError directly for guard failures; map backend assertion errors upward.
mithril-stm/src/circuits/halo2/gadgets/lottery.rs	Return StmCircuitError for lottery gadget assertions; adjust focused tests.
mithril-stm/src/circuits/halo2/gadgets/comparison.rs	Propagate StmCircuitError from comparison helpers and assertions.
mithril-stm/src/circuits/halo2/gadgets/comparison_helpers.rs	Convert helper APIs to StmCircuitError for typed propagation.
mithril-stm/src/circuits/halo2/errors.rs	Add backend catch-all + From<plonk::Error> to satisfy new Relation::Error bound; add unit test.
mithril-stm/src/circuits/halo2/circuit.rs	Set Relation::Error = StmCircuitError; remove synthesis flattening; update cost model calls and chips.
mithril-stm/src/circuits/halo2/bench_helpers.rs	Update cost model and MockProver API usage; update circuit degree calculation.
mithril-stm/src/circuits/halo2_ivc/witness_assignments.rs	Rename VK name constants to fixed-base prefixes throughout witness assignment.
mithril-stm/src/circuits/halo2_ivc/tests/off_circuit/proof_verification.rs	Use verifier params (not tau_g2) in accumulator checks.
mithril-stm/src/circuits/halo2_ivc/tests/off_circuit/mod.rs	Rename extraction-focused module references to resolution-focused ones.
mithril-stm/src/circuits/halo2_ivc/tests/off_circuit/fixed_base_resolution.rs	New tests for resolve_fixed_bases behavior/idempotency.
mithril-stm/src/circuits/halo2_ivc/tests/off_circuit/fixed_base_extraction.rs	Removed extraction tests (superseded by resolution approach).
mithril-stm/src/circuits/halo2_ivc/tests/off_circuit/accumulator_verification.rs	Use verifier params for accumulator checks.
mithril-stm/src/circuits/halo2_ivc/tests/off_circuit/accumulator_update.rs	Update pipeline to from_dual_msm/verifier params; remove extract step assumptions.
mithril-stm/src/circuits/halo2_ivc/tests/off_circuit/accumulator_construction.rs	Add negative test for fixed-base prefix mismatch detection.
mithril-stm/src/circuits/halo2_ivc/tests/off_circuit/accumulator_collapse.rs	Align collapse tests with from_dual_msm + verifier params flow.
mithril-stm/src/circuits/halo2_ivc/tests/golden/positive.rs	Update golden checks to pass verifier params into accumulator checks.
mithril-stm/src/circuits/halo2_ivc/tests/encoding/positive.rs	Add golden serialization test for recursive proof accumulator bytes.
mithril-stm/src/circuits/halo2_ivc/tests/common/helpers.rs	Update MockProver usage and accumulator construction via from_dual_msm; remove stored tau_g2.
mithril-stm/src/circuits/halo2_ivc/tests/common/generators/verification_key.rs	Update circuit degree computation for new MidnightCircuit API.
mithril-stm/src/circuits/halo2_ivc/tests/common/generators/transitions.rs	Update fixed-base prefix usage and accumulator construction via from_dual_msm.
mithril-stm/src/circuits/halo2_ivc/tests/common/generators/setup.rs	Rename constants and fixed-base prefix usage in setup generators.
mithril-stm/src/circuits/halo2_ivc/tests/common/generators/proofs.rs	Adjust proof generation call signature ordering.
mithril-stm/src/circuits/halo2_ivc/tests/common/generators/asset_generation.rs	Update accumulator construction/checks to verifier params + from_dual_msm; add ignored asset generator.
mithril-stm/src/circuits/halo2_ivc/tests/common/asset_readers.rs	Stop extracting/storing tau_g2 from embedded verifier params bytes.
mithril-stm/src/circuits/halo2_ivc/tests/assets/README.md	Document new ignored asset-generation command.
mithril-stm/src/circuits/halo2_ivc/mod.rs	Rename VK-name constants to fixed-base prefix constants; update foreign ECC chip imports.
mithril-stm/src/circuits/halo2_ivc/errors.rs	Add error variant for MSM/fixed-base mismatch detection.
mithril-stm/src/circuits/halo2_ivc/constraint_builder.rs	Update to ForeignWeierstrassEccChip API and verifier gadget prepare signature changes.
mithril-stm/src/circuits/halo2_ivc/config.rs	Adapt IVC circuit configuration to new weierstrass foreign-ECC chip configuration API.
mithril-stm/src/circuits/halo2_ivc/accumulator.rs	Remove com_instance dummy fixed base; add MSM/fixed-base consistency check helper.
mithril-stm/CHANGELOG.md	Add 0.11.0 entry describing dependency upgrades and key/fixed-base changes.
mithril-stm/Cargo.toml	Bump crate version and pin upgraded midnight-* crate versions.
mithril-common/Cargo.toml	Update mithril-stm dependency version to 0.11.0.
docs/runbook/update-circuit-keys/README.md	Update runbook checklist with nr_pow2range_cols guidance.
Cargo.lock	Lockfile updates for upgraded dependencies and new transitive crates.

[damrobi]

LGTM 👍

[jpraynaud]

LGTM 👍