feat(backend): implement consistency checks for task registration and…

[OkeyAmy]

Close #275

This PR implements consistency checks for task registration and sequential ID allocation in the SoroTask smart contract, as requested by the maintainer.

Changes Made

1. Documentation (contract/src/lib.rs)

• Added comprehensive docstring to register() function explaining:
  • ID Allocation Rules: Monotonically increasing, starts at 1, never reused, invalid registrations don't increment counter
  • Safe Assumptions for Downstream Tooling: IDs are positive integers, always increasing, one-to-one mapping
  • Assumptions to AVOID: IDs are NOT contiguous (cancellations create gaps), counter persists across upgrades

2. Consistency Check (contract/src/lib.rs:170-176)

• Added defensive check in register() to verify the newly allocated ID doesn't already have stored task data
• Guards against counter corruption or storage inconsistencies

3. New Public Function (contract/src/lib.rs:202-213)

• Added get_counter(env) -> u64 to expose current counter value
• Allows downstream tooling to verify ID allocation consistency

4. Expanded Test Suite (5 new tests)

Test	Purpose
test_id_counter_not_incremented_on_invalid_registration	Failed registrations don't waste IDs
test_sequential_ids_multiple_registrations	100 consecutive registrations work correctly
test_id_uniqueness	All 50 task IDs are unique (pairwise verification)
test_id_not_reused_after_cancel	Cancelled task IDs aren't reused
test_id_monotonically_increasing	Each new ID exceeds all previous ones

Test Results

• 72 tests passed, 0 failed
• All new tests pass
• No regressions introduced

Acceptance Criteria Verification

• ✅ Registration and ID behavior are explicitly tested (5 new tests)
• ✅ Downstream assumptions are clearer (docstring on register() and get_counter())
• ✅ Edge cases covered: invalid registration, cancellation, multiple registrations, uniqueness, monotonicity
• ✅ Tests are readable with clear docstrings for contributors unfamiliar with the contract

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[ayomideadeniran]

pr under review, if i find any wrong implementation i will notify you.

[ayomideadeniran]

pr under review, if i find any wrong implementation i will notify you.

[ayomideadeniran]

pr under review, if i find any wrong implementation i will notify you.

[OkeyAmy]

@ayomideadeniran Check pr

[OkeyAmy]

@Henrichy review pr