sTitle: [contract] Emission Schedule, Anti-Whale, Proposal Cancellation & Token/Staking Lifecycle Tests

[Emeka000]

Description:

Closes #712,

closes #713
Closes #714,

closes #715

This PR implements four Soroban smart contract features for the Nestera protocol in a single cohesive change.

Changes
#712 — Emission Schedule
Introduces
emission.rs
— a new module that defines how new NST tokens are released over time.

EmissionConfig struct stores emission_rate_per_second, max_supply, last_emission_time, total_emitted, and active flag
initialize_emission() — admin-only, one-time setup
update_emission_config() — admin or active governance can adjust rate, cap, or pause emissions
process_emission(recipient) — mints all tokens accrued since the last call; enforces the supply cap automatically
is_supply_cap_reached() — read-only cap status check
All arithmetic uses checked math with overflow protection
Events emitted: EmissionConfigSet, TokensEmitted
#713 — Anti-Whale & Fair Distribution
Extends StakingConfig with two new fields and enforces them in the staking logic.

max_staking_limit: i128 — maximum tokens a single user may have staked in total (0 = no limit). Checked cumulatively on every stake() call
max_wallet_holding: i128 — maximum token balance a single wallet may hold (0 = no limit). Enforced via validate_wallet_holding() helper
default_staking_config() defaults both to 0 (no limits) for backward compatibility
No bypass is possible — limits are checked before any state mutation
#715 — Governance Proposal Cancellation
Upgrades the existing cancel_proposal stub into a fully spec-compliant implementation.

Added canceled: bool field to both Proposal and ActionProposal structs (replaces the previous workaround of setting executed = true)
Cancellation is allowed for: proposal creator OR contract admin / active governance
Already-executed proposals cannot be canceled (TooLate)
Already-canceled proposals cannot be canceled again (TooLate)
Queued proposals can still be canceled before execution
vote(), queue_proposal(), and execute_proposal() all reject canceled proposals
ProposalCanceled event emitted on success
#714 — Token & Staking Integration Tests
New test file
token_staking_lifecycle_test.rs
with 27 tests covering the full token lifecycle and all features in this PR.

Full lifecycle flow:

Mint → distribute rewards → stake → accrue staking rewards → unstake & claim → burn → participate in governance
Emission tests: init, double-init guard, correct amount per elapsed time, supply cap enforcement, pause behavior, rate update, unauthorized access blocked

Governance cancellation tests: creator cancel, admin cancel, unauthorized blocked, executed proposal blocked, double-cancel blocked, queued proposal can be canceled

Anti-whale tests: limit enforced, no limit when zero, per-user isolation, at-limit allowed, one-over-limit rejected, cumulative enforcement across multiple stakes, restake after unstake, below-minimum rejected, disabled staking rejected

Files Changed
File Change
emission.rs
New — emission schedule module
governance.rs
Updated — canceled field, full cancel_proposal implementation
storage_types.rs
Updated — max_wallet_holding, max_staking_limit fields
storage.rs
Updated — anti-whale enforcement in stake(), validate_wallet_holding() helper, updated default config
lib.rs
Updated — mod emission, cancel_proposal, and 5 emission public functions wired in
token_staking_lifecycle_test.rs
New — 27 integration tests
Testing
All 27 new tests pass. No existing tests were broken. All diagnostics are clean across all modified files.

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Project	Deployment	Actions	Updated (UTC)
nestera	Ready	Preview, Comment	Apr 29, 2026 3:05am

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