Harden propose_admin_transfer against unauthorized caller and illegal source state (#346)

[d3vobed]

Summary

Closes #346

Hardens propose_admin_transfer so it rejects unauthorised callers and illegal source states with specific typed errors, performing no ledger mutation on any rejected path.

• Adds an explicit require_initialized() precondition, checked before any other ledger access (the contract's init marker is DataKey::Version, set by initialize).
• The function already enforces require_admin (auth + stored-admin match → Unauthorized) and the AdminTransferPending / InvalidAddress preconditions; the new init check sits first so an uninitialised contract is rejected up-front.
• Adds comprehensive tests asserting the typed errors (Unauthorized, AdminTransferPending, InvalidAddress, NotInitialized) and verifying the pending-admin-transfer ledger entry is never written on a rejected call.

Verification

cargo test in contracts/milestone-escrow — all tests pass (incl. the 5 new ones).

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[godamongstmen897]

FIX FAILED CI @d3vobed

[d3vobed]

Heads-up for reviewers: the 2 failing CI checks (test_tax_withholding_deductions_terminal_milestone_fails_without_event, test_tax_withholding_record_can_be_resolved_as_net_release) are a pre-existing main-wide breakage, not introduced by this PR.

main's Cargo.lock pins soroban-sdk 22.0.11, which forces soroban-env-host = "=22.1.3". That env-host version has an auth regression (Error(Auth, ExistingValue) — "frame is already authorized") that breaks these two tax-withholding tests identically on main itself. Every open PR on the repo hits them.

This PR's own propose_admin_transfer hardening tests all pass. Recommended repo-wide fix: downgrade soroban-sdk (or pin soroban-env-host to a 22.0.x) in main's Cargo.lock.

[godamongstmen897]

Thanks @d3vobed — the hardening here is right, but the branch doesn't compile, and one of the problems isn't something I can fix for you without inventing your test.

1. A test is truncated and spliced into the next one. test_propose_admin_transfer_unauthorized_no_mutation stops mid-setup and the following test's header lands inside its body:

fn test_propose_admin_transfer_unauthorized_no_mutation() {
    ...
    let token = env.register_stellar_asset_contract_v2(admin.clone()).address();
#[test]
fn test_set_platform_fee_allocation_emits_structured_event() {

The two initialize calls then merge into one with ten arguments instead of seven (&admin, &client_addr, &freelancer, &arbiter, &token, followed by &admin_addr, &client_addr, &freelancer_addr, &arbiter_addr, &token_contract_id). test.rs ends up with 602 { against 601 }, so the whole file fails with "this file contains an unclosed delimiter".

test_set_platform_fee_allocation_emits_structured_event I can restore from main. The other half I can't: test_propose_admin_transfer_unauthorized_no_mutation is new in this PR — it isn't on main or in your merge base — so the missing body is your work, and guessing at it would be me writing the test rather than reviewing it. Your other four propose_admin_transfer tests are intact.

2. mod test is declared twice.

#[cfg(test)]
pub(crate) mod test;
mod test;

The second line is left over from before. Only the pub(crate) one should stay.

3. The doc checklist is duplicated. admin_override_cancel_refund's # Checks (in order) now lists 1–4 and then the old 1–3 immediately after.

The actual change is sound and worth landing. require_initialized keyed on DataKey::Version is a clean initialisation marker, and calling it before require_admin in propose_admin_transfer means an uninitialised contract returns NotInitialized rather than Unauthorized — which is the more useful answer and matches how admin_set_yield_rate orders its preconditions.

Suggested path: rebase on main, drop the stray mod test;, fix the doc list, and restore both test functions — test_set_platform_fee_allocation_emits_structured_event verbatim from main, and your unauthorized-no-mutation case with its body intact. I'd expect it to go green after that; nothing else in the branch looked wrong.