[Quality] Build invariant and fuzz coverage for core commitment flows

[1nonlypiece]

Problem

Example-based tests do not sufficiently explore interleavings of create, fund, settle, cancel, fee, and expiry operations.

This issue requires a meaningful production implementation. Typo-only, documentation-only, formatting-only, dependency-only, or cosmetic changes do not satisfy the scope.

Objective

Add a bounded stateful/property test model that checks core financial and ownership invariants.

Scope

Define the model state, generated commands, shrinking, reproducible seeds, and a CI runtime budget.

Acceptance criteria

• Generated sequences preserve principal, fee, and ownership invariants.
• Invalid command sequences fail safely without partial mutation.
• Failures include a replayable seed and minimized command sequence.
• The suite runs deterministically within the CI budget.
• Existing CI/CD checks remain green.
• The PR explains the design, tradeoffs, test evidence, and any remaining limitations.
• The PR references this issue with Closes #{issue-number} or Fixes #{issue-number}.

Implementation notes

Implement only the stated behavior; keep unrelated refactors out of the PR.

Non-goals

• Do not remove tests merely to make CI pass.
• Do not introduce secrets, private keys, credentials, or mainnet-only values.
• Do not change unrelated APIs, UI surfaces, contract behavior, or deployment configuration.

Contributor application

Before starting, comment with relevant experience, a 1–4 bullet implementation approach, and an estimate for opening the first draft PR. Wait for maintainer assignment before coding. Only the assigned contributor is eligible for reward consideration.

Submission requirements

• Use PR title format [#<issue-number>] <short summary>.
• Check off each completed acceptance criterion.
• Include focused automated tests for success, failure, authorization, and boundary behavior where applicable.
• Include the validation commands and results in the PR description.
• Address maintainer review feedback before merge.

GrantFox reward consideration is based on the original scope, implementation quality, tests, security review, CI/CD results, review feedback, and follow-up stability; completion or merge alone is not a guarantee.

[safal207]

Hi — this is a very strong match with my recent lifecycle and invariant-testing work.

Relevant experience:
I focus on state-machine verification for financial and escrow flows. In a recent escrow assessment, lifecycle analysis exposed a material funds-liveness issue that ordinary function-level tests had missed. I also work with deterministic regression/property-style tests around replay, settlement, and conservation.

Approach for #554:

• model create, fund, settle, cancel, fee, and expiry as generated state transitions;
• define principal, fee, ownership, and terminal-state invariants;
• ensure invalid sequences leave state unchanged;
• produce deterministic seeds and minimized replayable failing sequences.

First draft PR: within 1 day after maintainer assignment.

I’ll wait for assignment before implementation.

[1nonlypiece]

Hi @safal207 — good luck, you are now assigned to this issue: #554

Please read the full issue description before starting. This task is specifically about building deterministic, stateful invariant and fuzz coverage for the commitment lifecycle. Your PR should address the complete scope: model create, fund, settle, cancel, fee, and expiry sequences; verify principal, fee, ownership, and terminal-state invariants; ensure invalid sequences leave state unchanged; and provide minimized, replayable failure seeds.

Please raise a quality PR that addresses every acceptance criterion, includes focused success/failure/boundary tests, explains the design and tradeoffs, and reports the validation commands and results. Use the required issue reference in the PR and keep unrelated changes out of scope.

Please open the PR within 48 hours of this assignment, by 2026-08-26 10:03 UTC. If no PR is opened by then, I will unassign the issue. If you hit a blocker, comment here before the deadline so it can be reviewed. Good luck — I look forward to seeing the invariant model and reproducible test coverage.

[safal207]

Thanks for merging #556. I noticed #554 was closed as completed and then reopened a few minutes later. Could you clarify whether the reopened state signals any remaining technical work within the original #554 acceptance criteria, or whether it is only for GrantFox/campaign review bookkeeping?

If there is any concrete in-scope follow-up, please point me to it and I’ll address it. Otherwise, I’ll await the campaign review.

[safal207]

Friendly follow-up on #554: PR #556 has been merged and covers the original acceptance criteria. If the issue was reopened only for campaign bookkeeping, could you please close it as completed so it can proceed to GrantFox review?

If any concrete in-scope work is still required, please point me to the specific missing criterion and I’ll address it promptly.