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fix(platform-wallet): auto_select_inputs honors Σ inputs == Σ outputs#3554

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fix(platform-wallet): auto_select_inputs honors Σ inputs == Σ outputs#3554
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@Claudius-Maginificent Claudius-Maginificent commented Apr 28, 2026

Issue

auto_select_inputs in packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs was inserting each selected address with its full balance as the input's Credits value, then returning as soon as accumulated covered output + fee. The address-funds-transfer protocol enforces Σ inputs.credits == Σ outputs.credits (strict equality), so a bank with ~500B credits funding a 50M output produced:

inputs  = { bank: 499_985_086_740 }
outputs = { target: 50_000_000 }
→ rejected: "Input and output credits must be equal"

Verified at rs-dpp/.../address_funds_transfer_transition/v0/state_transition_validation.rs and asserted on-chain by rs-drive-abci/.../address_funds_transfer/tests.rs::test_input_balance_decreased_correctly (new_balance == initial_balance - transfer_amount - fee).

Protocol semantics (now respected)

  • inputs[addr].credits = consumed amount from addr
  • outputs[addr] = credited amount to addr
  • Σ inputs.credits == Σ outputs.credits (strict equality)
  • Fee is deducted from the targeted input's remaining balance (post-consumption) per AddressFundsFeeStrategy. DeductFromInput(0) reduces the remaining balance by the fee — never the inputs map's Credits value
  • Every input must satisfy consumed >= min_input_amount (currently 100_000)

What changed

auto_select_inputs now respects the protocol contract:

  • Σ inputs.credits == Σ outputs.credits (strict equality) — selection trims so the inputs map sums to exactly total_output.
  • Fee headroom on DeductFromInput(0) target — the lex-smallest selected input retains at least estimated_fee of remaining balance.
  • min_input_amount enforcement — candidates below the floor are filtered upfront; Phase-4 distribution rolls sub-minimum residue into the fee target.
  • Output-address exclusion — addresses appearing in both candidate-input and transition-output sets are filtered out before selection (the canonical "self-funded transition" case that the protocol rejects).
  • Descending-balance candidate order — mirrors dash-evo-tool's allocator; collapses many cases to a single input.
  • InputSelection::Auto fee strategies supported: [DeductFromInput(0)] and [ReduceOutput(0)]. Any other shape returns a clear error redirecting to InputSelection::Explicit.
  • Defensive arithmeticchecked_add / saturating_sub on Credits throughout the selector path; overflow produces typed errors instead of wrapping.
  • Phase-3 retry on infeasibility — when fee_target_min > fee_target_max, the algorithm extends the prefix with the next candidate and retries instead of erroring out.

CI gap also closed in this PR: rs-platform-wallet was missing from .github/package-filters/rs-packages-no-workflows.yml, so Rust workspace tests had been skipping silently. The filter entry mirrors the existing pattern (path + *sdk alias). The previously-hidden Rust 1.92 clippy lints (in core_bridge.rs, wallet/apply.rs:316, tests/spv_sync.rs) are cleared in the same PR because they were blocking once CI started exercising the crate.

Commit history (initial 5-commit review wave for blame)

  1. aaf8be74 — initial Σ inputs == Σ outputs fix. Extracted the selection loop into a pure module-scope helper select_inputs that walks candidates and trims the result so the inputs map sums to exactly total_output.

  2. 9ea9e703 — fee-headroom guarantee at DeductFromInput(0) target (CodeRabbit critical). The original fix proved aggregate balance covered the fee but not that the specific fee-bearing input had remaining headroom. Now identifies the prospective fee target (lex-smallest of selected) and reserves at least estimated_fee of remaining balance on it.

  3. 687b1f86 — protocol-level reproduction test. Reconstructs the OLD buggy selector output for the CodeRabbit example, feeds the post-consumption input_current_balances through dpp::address_funds::fee_strategy::deduct_fee_from_outputs_or_remaining_balance_of_inputs, and asserts !fee_fully_covered. Proves the rejection at the protocol layer rather than asserting "the new output looks different."

  4. 60f7850a — sort candidates by balance descending (mirrors dash-evo-tool's allocator). Reduces the frequency of multi-input cases — when the largest single balance covers total_output + fee, the result is a 1-input map and the lex-smallest fee-target headroom logic doesn't fire at all. Bonus: fee_headroom_violation_errors now produces a debuggable error message.

  5. 9ff937ff — second review wave (4 blocking, 1 suggestion):

    • min_input_amount enforcement. auto_select_inputs filters candidates < min_input_amount upfront; Phase 4 distribution rolls any sub-minimum tail residue back into the fee target's consumption rather than producing an InputBelowMinimumError-prone tail.
    • fee_strategy restriction in transfer(). InputSelection::Auto now rejects any shape other than [DeductFromInput(0)] with a clear redirect to InputSelection::Explicit. The previous fallback path was publicly reachable but only protocol-correct for that single shape.
    • Phase 3 retry on infeasibility. When fee_target_min > fee_target_max, the algorithm extends the prefix with the next candidate and retries instead of erroring out — larger prefixes can yield a different lex-smallest fee target with sufficient headroom.
    • Early total_output < min_input_amount error (replaces the internal-error fallthrough).
    • Validator-based test assertions. assert_selection_validates helper builds an AddressFundsTransferTransitionV0 from each selector test's output and runs validate_structure. Catches future protocol-level regressions without depending on testnet.

CI / infrastructure (3 commits)

  1. 79c2b285ci(rs-packages-filter): trigger Rust workspace tests on rs-platform-wallet changes. The path filter at .github/package-filters/rs-packages-no-workflows.yml didn't list rs-platform-wallet, so any crate-only change there evaluated rs-packages = '[]' and Rust workspace tests silently skipped. This PR's prior 5 commits had never been validated by Rust CI — only by local cargo test. The filter entry mirrors the existing pattern (path + *sdk alias for transitive triggers).

  2. d610502 — merge v3.1-dev (9bd37f203a).

  3. 3c4f9199 — Rust 1.92 clippy hardening that the previously-skipped pipeline had been quietly accumulating:

    • field_reassign_with_default in core_bridge.rs::build_core_changeset → struct literal init
    • let_unit_value in wallet/apply.rs:316 (WalletInfoInterface::update_balance returns ()) → drop the let _ =
    • Stale core.chain.synced_height access in tests/spv_sync.rs → flattened to core.synced_height (struct shape changed upstream; the test never recompiled because workspace tests were skipping)

Tests (138 lib tests, all passing)

auto_select_tests module — 13 tests:

  • single_input_oversized_balance_trims_to_output_amount
  • descending_order_picks_single_largest_when_sufficient
  • pre_fix_buggy_selector_output_is_rejected_by_protocol_fee_deduction — protocol-level reproduction (asserts !fee_fully_covered)
  • fee_headroom_violation_errors
  • non_fee_target_below_min_input_redistributes
  • auto_select_inputs_excludes_output_addresses — confirms self-funded-transition filter
  • total_output_below_min_input_amount_errors
  • no_candidates_errors
  • reduce_output_happy_path_single_input — confirms [ReduceOutput(0)] strategy parity with [DeductFromInput(0)]
  • detect_no_selectable_inputs_combines_both_cases — pins the NoSelectableInputs variant fields (funded_outputs, sub_min_count, sub_min_aggregate)
  • augment_outputs_with_change_adds_residual_output
  • augment_outputs_with_change_rejects_duplicate_address
  • augment_outputs_with_change_rejects_no_surplus

Several assert structural validity via assert_selection_validatesAddressFundsTransferTransitionV0::validate_structure.

Note on withdrawal selector

The auto_select_inputs_for_withdrawal rustdoc clarifies the asymmetry: withdrawal validates Σ inputs > output_amount (strictly greater, surplus = fee), so its drain-everything strategy is correct by design. Not the same bug; no code change.

Verification

  • cargo fmt -p platform-wallet --check
  • cargo clippy --workspace --tests -- -D warnings
  • cargo test -p platform-wallet --lib138/138 passing
  • CI exercising the crate (path filter fixed in this PR)

Test plan

  • Unit tests cover trim invariant in single- and multi-input cases
  • Regression test for fee-only-tail-input case
  • Protocol-level reproduction proves the pre-fix output is rejected by deduct_fee_from_outputs_or_remaining_balance_of_inputs
  • Validator-based test assertions on 5 selector tests
  • Signatures stable — transfer(), auto_select_inputs, select_inputs unchanged. Backward-compatible additions only: new WalletError::NoSelectableInputs struct variant (replacing the prior generic insufficient-balance message) and InputSelection::Auto now accepts [ReduceOutput(0)] in addition to [DeductFromInput(0)]. Downstream exhaustive matches on WalletError need updating.
  • Workspace clippy clean under Rust 1.92
  • Rust workspace tests now triggered by path filter
  • Live e2e re-run on testnet via test(platform-wallet): e2e framework + full test suite — triage pins, Found-*/PA-* guards, fail-closed persist, Stage-2 merge #3549 once both merge

Provenance

Originally surfaced and fixed during work on PR #3549 (rs-platform-wallet e2e harness). Split out so the production-code fix can ship independently of the long-running e2e branch. Subsequent commits address review feedback from CodeRabbit and thepastaclaw reviewers and close a CI coverage gap that was hiding pre-existing breaks on v3.1-dev.

🤖 Generated with Claude Code

Triage wave (11 commits, 2026-05-21)

Applied 9 of 11 triaged findings from a fresh grumpy-review + comment-verification pass at HEAD d5d2b3d271. 2 deferred as out-of-scope TODOs.

Commit Finding Sev Summary
098484f34f QA-001 HIGH augment_outputs_with_change now rejects change_amount < min_output_amount via typed ChangeBelowMinimumOutput; platform_version plumbed; (0, min_output_amount) band test added
8ee78a4f60 CMT-001 LOW InputSelection::Auto rustdoc rewritten to current contract (balance-desc, dust filter, output-address exclusion, supported fee strategies, typed errors)
3aeed87bfa CMT-002 LOW is_empty_no_records() now includes addresses_derived, matching canonical CoreChangeSet::is_empty()
6c3fb02b0c QA-003 MED Defensive balance-descending sort in select_inputs_reduce_output and select_inputs_deduct_from_input; invariant documented
e2140bd475 QA-004 MED Post-Phase-4 fee recompute against selected.len() instead of prefix.len(); eliminates false "insufficient funds" on objectively spendable wallets
b85b6a9a90 QA-005 LOW OnlyOutputAddressesFunded now carries sub_min_count + sub_min_aggregate to preserve dust diagnostics under the combined case
cfe3c33247 QA-006 LOW checked_sum_credits + InputSumOverflow for caller-supplied input maps in transfer_with_change_address; trusted call sites still saturate
9854e38674 QA-002 MED (breaking) outputs now typed as IndexMap<PlatformAddress, Credits> so caller controls "output 0" insertion order; [ReduceOutput(0)] + Some(change_addr) rejects when change_addr is lex-smaller than every user output
9c136cd912 CMT-003 LOW New FFI codes ErrorOnlyOutputAddressesFunded = 13 and ErrorOnlyDustInputs = 14; Swift PlatformWalletResultCode + typed PlatformWalletError mirrored; table-driven Rust test pins routing
7c7a2ec585 QA-007 / CMT-004 LOW TODO markers for two deferred follow-ups (pre-existing read-snapshot/broadcast race; missing balance-hydration regression test)
2957623756 cargo fmt --all cleanup

Triage decisions

  • Fixed (9): QA-001, QA-002, QA-003, QA-004, QA-005, QA-006, CMT-001, CMT-002, CMT-003
  • Deferred (2): QA-007 (pre-existing race, out of PR scope), CMT-004 (test gap on file outside PR diff)

Verification

  • cargo fmt --all --check
  • cargo clippy -p platform-wallet -p platform-wallet-ffi --all-targets -- -D warnings
  • cargo test -p platform-wallet --lib144 passing
  • cargo test -p platform-wallet-ffi --lib75 passing (incl. new typed_errors_route_to_dedicated_codes)

Known follow-ups (out of PR scope)

  • DPP AddressFundsTransferTransition outputs are still BTreeMap at the chain layer; the IndexMap is a wallet-only affordance. A doc comment on the DPP transition struct cross-referencing the wallet semantics would help future readers — separate PR.
  • FFI parse_outputs overwrites duplicate-address entries silently. Pre-existing behavior, but worth a sanity rejection in a follow-up.

🤖 Co-authored by Claudius the Magnificent AI Agent

`auto_select_inputs` in `wallet/platform_addresses/transfer.rs` was
inserting each selected address with its FULL balance as the input's
`Credits` value, then returning as soon as accumulated covered
`output + fee`. With a bank holding ~500B credits and a 50M output, the
SDK got `inputs = {bank: 499_985_086_740}, outputs = {target: 50_000_000}`
and the protocol rejected it because address-funds-transfer enforces
`Σ inputs.credits == Σ outputs.credits` (strict equality, verified at
`rs-dpp/.../address_funds_transfer_transition/v0/state_transition_validation.rs`,
asserted on-chain by
`rs-drive-abci/.../address_funds_transfer/tests.rs::test_input_balance_decreased_correctly`,
which checks `new_balance == initial_balance - transfer_amount - fee`).

The protocol's actual semantics:
- `inputs[addr].credits` = consumed amount from `addr`
- `outputs[addr]` = credited amount to `addr`
- `Σ inputs.credits == Σ outputs.credits`
- Fee is deducted from the targeted input's REMAINING balance (post-
  consumption) per `AddressFundsFeeStrategy`. `DeductFromInput(0)`
  reduces the *remaining balance* by the fee — never the inputs map's
  `Credits` value.

Fix: extract the selection loop into a pure module-scope helper
`select_inputs(candidates, outputs, total_output, fee_strategy,
platform_version)` that:

1. Walks candidates in DIP-17 order, tentatively appending each to a
   `Vec<(address, balance)>` to drive the per-iteration fee estimate.
2. Stops when `accumulated >= total_output + estimated_fee` (the
   accumulated balance must cover the fee from the last input's
   remaining balance).
3. Builds the returned map front-to-back, consuming each input in
   insertion order until exactly `total_output` is reached. Inputs
   added solely to satisfy the per-input fee margin are excluded
   from the final map — preserving Σ inputs.credits == total_output
   without violating `min_input_amount`.

Side benefits:
- The pure helper is unit-testable without constructing a full
  `PlatformWalletManager` + `PlatformAddressWallet`. Five tests cover
  the fix:
    - `single_input_oversized_balance_trims_to_output_amount`
    - `two_input_selection_trims_only_the_last`
    - `fee_only_tail_input_does_not_inflate_input_sum` (regression for
      the Σ-inputs-greater-than-Σ-outputs case raised in Copilot review)
    - `insufficient_balance_errors`
    - `no_candidates_errors`
- The full per-`PlatformAddressWallet` async method `auto_select_inputs`
  now just gathers `(address, balance)` candidates and calls
  `select_inputs`, which keeps the testability win without changing
  public API.

Doc note in `auto_select_inputs_for_withdrawal` clarifies the
asymmetry: withdrawal validates `Σ inputs > output_amount` (strictly
greater, surplus = fee), so its drain-everything strategy is correct
by design — NOT the same bug as the transfer selector. No code
change there.

Verification:
- `cargo check --tests -p platform-wallet`             OK
- `cargo clippy --tests -p platform-wallet -- -D warnings` OK
- `cargo fmt -p platform-wallet`                        OK
- `cargo test -p platform-wallet --lib`                 115/115

Co-Authored-By: Claudius the Magnificent <noreply@anthropic.com>
@github-actions github-actions Bot added this to the v3.1.0 milestone Apr 28, 2026
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📝 Walkthrough

Walkthrough

Restricts auto input-selection to a single fee-strategy shape and replaces the greedy selector with a deterministic, tested pure selector; plus small refactors and test/adaptations and a package-filter addition.

Changes

Cohort / File(s) Summary
Input selection & tests
packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs
Restricts InputSelection::Auto to the single supported fee-strategy [DeductFromInput(0)]; replaces previous greedy ascending selector with snapshot/filter → sort (descending) → pure select_inputs helper that returns per-address consumed credits summing to total_output, preserves fee headroom for the lexicographically-smallest DeductFromInput(0) target, folds sub-min_input_amount tail into fee target, and exposes estimate_fee_for_inputs_pub. Adds comprehensive unit and protocol-layer regression tests.
Core changeset projection
packages/rs-platform-wallet/src/changeset/core_bridge.rs
Rewrites build_core_changeset projection to compute new_utxos/spent_utxos first and return a constructed CoreChangeSet literal instead of mutating a default via field reassignments.
Restore/apply behavior
packages/rs-platform-wallet/src/wallet/apply.rs
Calls self.core_wallet.update_balance() for side effects (no returned changeset used); updates inline docs to reflect update_balance returns () and to avoid clippy let_unit_value.
SPV sync test update
packages/rs-platform-wallet/tests/spv_sync.rs
Updates RecordingPersister::store to read synced_height from flattened CoreChangeSet (c.synced_height) instead of nested chain.synced_height, adjusting test persistence metadata observation.
Package filter addition
.github/package-filters/rs-packages-no-workflows.yml
Adds new package filter group rs-platform-wallet matching packages/rs-platform-wallet/** and including *sdk dependency set.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~40 minutes

Poem

🐰 I hopped through balances, tails in a row,
Picked the fattest coins so fees still could grow,
Folded tiny crumbs into the pot,
Wrote tests that thumped — no corner forgot,
A tiny rabbit happy to watch ledgers flow.

🚥 Pre-merge checks | ✅ 5
✅ Passed checks (5 passed)
Check name Status Explanation
Title check ✅ Passed The title accurately reflects the main bug fix: it specifies the component (auto_select_inputs), describes the core issue (honoring the sum equivalence property Σ inputs == Σ outputs), and directly addresses the central problem fixed in the PR.
Docstring Coverage ✅ Passed Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check ✅ Passed Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check ✅ Passed Check skipped because no linked issues were found for this pull request.
Description Check ✅ Passed Check skipped - CodeRabbit’s high-level summary is enabled.

✏️ Tip: You can configure your own custom pre-merge checks in the settings.

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  • Create PR with unit tests
  • Commit unit tests in branch fix/rs-platform-wallet-auto-select-inputs

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thepastaclaw commented Apr 28, 2026

✅ Review complete (commit 30e612b)

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs`:
- Around line 341-365: When building the final `selected` map after `accumulated
>= required`, ensure the address referenced by the fee strategy
`DeductFromInput(index)` is reserved the estimated fee before returning: locate
the `chosen` prefix and the loop that constructs `selected` using
`remaining`/`total_output`, compute the required fee headroom for the
fee-bearing input (from `fee_strategy`/`DeductFromInput`) and reduce that
input's available amount by that fee (i.e., instead of consuming up to
`remaining`, cap consumption so the fee-bearing input keeps at least
`estimated_fee`), and if that causes the input to be insufficient, continue
selecting additional candidates or return an error; update uses of `selected`,
`remaining`, `accumulated`, and `required` accordingly so the returned map
guarantees the fee-bearing input still has the reserved fee.
🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

  • Push a commit to this branch (recommended)
  • Create a new PR with the fixes

ℹ️ Review info
⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 56d75786-5d1c-44b8-a304-2e962f372120

📥 Commits

Reviewing files that changed from the base of the PR and between 844edba and aaf8be7.

📒 Files selected for processing (1)
  • packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs

Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
@lklimek lklimek changed the title fix(rs-platform-wallet): auto_select_inputs honors Σ inputs == Σ outputs fix(wallet): auto_select_inputs honors Σ inputs == Σ outputs Apr 28, 2026
@lklimek lklimek changed the title fix(wallet): auto_select_inputs honors Σ inputs == Σ outputs fix(platformwallet): auto_select_inputs honors Σ inputs == Σ outputs Apr 28, 2026
@lklimek lklimek changed the title fix(platformwallet): auto_select_inputs honors Σ inputs == Σ outputs fix(platform-wallet): auto_select_inputs honors Σ inputs == Σ outputs Apr 28, 2026
…arget

CodeRabbit caught a critical bug on PR #3554's `select_inputs`: the helper
ensured `Σ inputs.credits == Σ outputs.credits` (the protocol's structural
invariant) but did NOT ensure that the address targeted by
`DeductFromInput(0)` had post-consumption remaining balance >= the
estimated fee.

Worked example from CodeRabbit:
  candidates    = [(addr_a, 20M), (addr_b, 50M)]   // addr_a < addr_b lex
  total_output  = 30M
  fee_strategy  = [DeductFromInput(0)]
  Old result    = {addr_a: 20M, addr_b: 10M}       // Σ matches; addr_a drained
  Drive applies DeductFromInput(0) over inputs sorted by key (BTreeMap order),
  hitting addr_a — whose remaining balance is 0 — so `min(fee, 0) = 0`,
  `fee_fully_covered = false`, validator rejects with
  AddressesNotEnoughFundsError.

The Wave-8 single-input live e2e accidentally avoided this because the
fee target had ~1B credits left over after consumption — multi-input
auto-selected transfers would have hit it on first contact.

This rewrite:

- Phase 1 (unchanged): pick smallest DIP-17-ordered prefix covering
  total_output + estimated_fee.
- Phase 2: identify the fee target = lex-smallest address in the prefix
  (= `BTreeMap` index 0, what `DeductFromInput(0)` will hit per
   `rs-dpp/src/address_funds/fee_strategy/.../v0/mod.rs`).
- Phase 3: consume the *minimum* allowed amount from the fee target
  (`max(min_input_amount, total_output − Σ other balances)`) so it
  retains the most remaining balance for fee deduction. Error out
  with a descriptive AddressOperation if even that minimum leaves
  less than `estimated_fee` remaining.
- Phase 4: distribute the rest of `total_output` across the other
  prefix entries in DIP-17 order.
- Phase 5: defensive invariant checks.

`min_input_amount` is fetched from
`platform_version.dpp.state_transitions.address_funds.min_input_amount`
(currently 100k across v1/v2/v3 of platform-version).

For non-`[DeductFromInput(0)]` fee strategies the helper falls back to
the previous "consume from front" distribution that only enforces the
Σ invariant — none of the wallet's call sites use anything else today.

Tests:
- updated `two_input_selection_trims_only_the_last` →
  `two_input_selection_keeps_fee_headroom_at_index_zero` to assert the
  new distribution AND the headroom invariant.
- updated `fee_only_tail_input_does_not_inflate_input_sum`'s expected
  outputs (the tail is no longer dropped — it absorbs the consumption
  the fee target sheds).
- added `fee_target_keeps_remaining_for_fee_deduction` (CodeRabbit's
  exact scenario, with the headroom invariant as the load-bearing
  assertion).
- added `fee_headroom_violation_errors` (lex-smallest address too
  small to retain headroom → descriptive error rather than transition
  the validator will reject).
- `single_input_oversized_balance_trims_to_output_amount`,
  `insufficient_balance_errors`, `no_candidates_errors` pass unchanged.

`cargo test -p platform-wallet --lib` → 117 / 117 green
`cargo clippy -p platform-wallet --tests -- -D warnings` → clean
`cargo fmt -p platform-wallet --check` → clean

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Actionable comments posted: 3

🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs`:
- Around line 441-461: The distribution loop that sets each consumed = min(bal,
remaining) can insert inputs below min_input_amount (e.g., consumed <
min_input_amount); after that loop (the one that inserts entries into prefix and
uses variables fee_target_consumed, remaining, consumed, fee_target_addr),
validate all non-zero consumed values against min_input_amount and either (a)
rebalance by moving consumption from fee_target_consumed or other large entries
to bump small entries up to min_input_amount while preserving total consumption,
or (b) return an error indicating distribution impossible; implement the
simplest correct choice for your flow (prefer returning an error if safe
redistribution is complex) and ensure the function returns early on failure so
subsequent debug_asserts aren’t relied on.
- Around line 349-353: The code currently silently falls back to front-trimming
for any AddressFundsFeeStrategy other than the single-item [DeductFromInput(0)]
inside transfer()/where InputSelection::Auto is handled; change this to reject
unsupported auto-selection fee strategies by returning a clear error instead of
performing the unsafe fallback. Locate the branch handling InputSelection::Auto
in transfer.rs (the block that examines fee_strategy and falls back to
front-trimming) and add a guard that checks the strategy sequence—if it is not
exactly the single DeductFromInput(0) pattern, return an Err (with a descriptive
enum/variant or mapped error) indicating unsupported fee strategy for
auto-selection so callers cannot produce inputs that sum to outputs but will
fail on-chain once fees are applied. Ensure the new error flows out of
transfer() consistently with existing error types.
- Around line 363-385: The loop that builds the DIP-17-ordered prefix (variables
prefix, accumulated, covered) currently breaks out as soon as accumulated >=
required, which prevents trying larger prefixes when Phase 3 (fee target
feasibility using fee_target_min/fee_target_max and DeductFromInput(0)
semantics) fails; change the logic so that when a covering prefix is found you
run Phase 3 checks but do not return/error on Phase 3 failure—continue the for
(address, balance) in candidates iteration (calling estimate_fee_for_inputs_pub
as before) to grow the prefix and try later candidates until either Phase 3
succeeds or all candidates are exhausted, only then set covered/error
accordingly.
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Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
lklimek and others added 2 commits April 28, 2026 09:54
…ee-headroom bug

Adds `pre_fix_buggy_selector_output_is_rejected_by_protocol_fee_deduction`
to the `select_inputs` test module. Reconstructs the exact `inputs` map
the pre-fix `auto_select_inputs` would have returned for CodeRabbit's
example (candidates (20M, 50M), total_output 30M, `DeductFromInput(0)`),
runs the post-consumption remaining balances through the live dpp
fee-deduction code path, and asserts `fee_fully_covered == false` —
i.e. the protocol rejects it with `AddressesNotEnoughFundsError`.

Distinct from `fee_target_keeps_remaining_for_fee_deduction`, which
asserts the new selector's output meets the headroom invariant. This
reproduction proves the bug at the protocol layer rather than merely
asserting "the new output looks different" — it would have stayed red
without the fix in 9ea9e70.

Verification:
- cargo check --tests -p platform-wallet                 OK
- cargo clippy --tests -p platform-wallet -- -D warnings OK
- cargo fmt -p platform-wallet                           OK
- cargo test -p platform-wallet --lib                    118/118

Co-Authored-By: Claudius the Magnificent <noreply@anthropic.com>
…descending

Internal-only change to `auto_select_inputs`. Candidates were
previously collected in DIP-17 derivation index order; now they
sort by balance descending before being handed to `select_inputs`.

Mirrors the dash-evo-tool allocator
(`src/ui/wallets/send_screen.rs:155-157`). Effects:

- Single largest balance covering `total_output + estimated_fee`
  => 1-input result, no multi-input case, no lex-smallest fee
  headroom logic firing. Common path simplified.
- Multi-input cases (when the largest alone isn't enough) still
  go through the headroom-respecting distribution introduced in
  9ea9e70 — unchanged, still correct.
- No public API change. `transfer()`, `auto_select_inputs`,
  `select_inputs` signatures all identical.

Adds `descending_order_picks_single_largest_when_sufficient` to
the existing test module to lock in the common-path behavior.
Other tests pass candidates directly to `select_inputs` and are
order-agnostic by design — unchanged.

The `fee_headroom_violation_errors` error message now includes
the fee-target address, its balance, required headroom, and
remaining-after-consumption to ease debugging.

Verification:
- cargo check --tests -p platform-wallet                 OK
- cargo clippy --tests -p platform-wallet -- -D warnings OK
- cargo fmt -p platform-wallet                           OK
- cargo test -p platform-wallet --lib                    119/119

Co-Authored-By: Claudius the Magnificent <noreply@anthropic.com>
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Actionable comments posted: 1

🧹 Nitpick comments (2)
packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs (2)

442-453: Fallback path for non-[DeductFromInput(0)] strategies still risks on-chain rejection.

The docstring at lines 371-375 acknowledges this limitation, but the code silently proceeds with a distribution that only guarantees Σ inputs == Σ outputs without reserving fee headroom on the actual fee-bearing input. If transfer() is ever called with a different fee strategy (e.g., DeductFromInput(1) or multi-step strategies), the returned inputs map could still fail on-chain when the targeted input lacks remaining balance for fee deduction.

A previous review suggested returning an error for unsupported strategies. The current approach documents the limitation but doesn't prevent misuse. Consider whether rejecting unsupported strategies is preferable to silent fallback with potential on-chain failure.

Alternative: Reject unsupported strategies explicitly
     if !single_deduct_from_input_zero {
-        let mut selected: BTreeMap<PlatformAddress, Credits> = BTreeMap::new();
-        let mut remaining = total_output;
-        for (addr, bal) in prefix.iter() {
-            if remaining == 0 {
-                break;
-            }
-            let consumed = (*bal).min(remaining);
-            selected.insert(*addr, consumed);
-            remaining = remaining.saturating_sub(consumed);
-        }
-        return Ok(selected);
+        return Err(PlatformWalletError::AddressOperation(
+            "Auto input selection currently supports only [DeductFromInput(0)] fee strategy. \
+             Other strategies require explicit input selection.".to_string(),
+        ));
     }
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.

In `@packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs` around
lines 442 - 453, The fallback branch that builds `selected` when
`!single_deduct_from_input_zero` must not silently return a transfer that may
fail on-chain; instead make `transfer()` validate the fee strategy up-front and
return an explicit error for unsupported strategies (e.g., when the strategy is
not `FeeStrategy::DeductFromInput(0)` or `single_deduct_from_input_zero` is
false). Replace the current loop-return branch that constructs `selected` with
an Err variant (create or reuse a `TransferError::UnsupportedFeeStrategy` or
similar), and ensure callers handle that error; keep the `prefix`-consumption
logic only for the supported `single_deduct_from_input_zero` path.

405-409: Phase 1 early break may cause false "fee headroom" failures when a larger prefix would succeed.

A previous review noted that because DeductFromInput(0) targets the lex-smallest address (not the first in iteration order), a later candidate joining the prefix can become the new fee target and make an otherwise-infeasible selection work. The current code breaks at the first covering prefix without checking Phase 3 feasibility.

With the descending-balance sort, this scenario is less common (the first candidates are the largest balances), but it can still occur when:

  1. The largest-balance address is also lex-smallest
  2. That address has just enough to cover total_output but not total_output + fee
  3. Adding a lex-smaller address would shift the fee-target role to a smaller-balance address with better headroom characteristics

Consider continuing to accumulate candidates until Phase 3 succeeds or all candidates are exhausted, rather than erroring immediately on the first Phase 3 failure.

🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.

In `@packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs` around
lines 405 - 409, The early break on the first prefix that meets accumulated >=
required causes false failures because Phase 3 (fee-target reassignment via
DeductFromInput(0)) may succeed for a larger prefix; in the loop that checks
accumulated, required and sets covered=true then break, remove the immediate
break and instead, after accumulated >= required, invoke the Phase 3 feasibility
check (the same logic that uses DeductFromInput(0) / the fee-target selection)
and only set covered=true and stop accumulating if that Phase 3 check succeeds;
if Phase 3 fails, continue accumulating more candidates and only error or mark
covered=false after all candidates are exhausted. Ensure you update the
variables used in the Phase 3 check to reflect the extended prefix and keep the
existing semantics for setting covered and returning an error when no prefix
passes Phase 3.
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs`:
- Around line 509-521: The loop that distributes `remaining` across `prefix` may
insert entries below `min_input_amount` because it uses `consumed =
bal.min(remaining)` without validating per-input minimum; update the Phase 4
loop (the block iterating `for (addr, bal) in prefix.iter()`) to only insert a
`consumed` value if `consumed >= min_input_amount`, otherwise do not insert that
address and instead add the small remainder to the `fee_target_addr` (or
accumulate it to be merged into the fee target while preserving any fee
headroom) so no non-fee-target input can be below `min_input_amount`; retain
existing `remaining`/`selected` semantics and keep the Phase 5 `debug_assert`
intact.

---

Nitpick comments:
In `@packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs`:
- Around line 442-453: The fallback branch that builds `selected` when
`!single_deduct_from_input_zero` must not silently return a transfer that may
fail on-chain; instead make `transfer()` validate the fee strategy up-front and
return an explicit error for unsupported strategies (e.g., when the strategy is
not `FeeStrategy::DeductFromInput(0)` or `single_deduct_from_input_zero` is
false). Replace the current loop-return branch that constructs `selected` with
an Err variant (create or reuse a `TransferError::UnsupportedFeeStrategy` or
similar), and ensure callers handle that error; keep the `prefix`-consumption
logic only for the supported `single_deduct_from_input_zero` path.
- Around line 405-409: The early break on the first prefix that meets
accumulated >= required causes false failures because Phase 3 (fee-target
reassignment via DeductFromInput(0)) may succeed for a larger prefix; in the
loop that checks accumulated, required and sets covered=true then break, remove
the immediate break and instead, after accumulated >= required, invoke the Phase
3 feasibility check (the same logic that uses DeductFromInput(0) / the
fee-target selection) and only set covered=true and stop accumulating if that
Phase 3 check succeeds; if Phase 3 fails, continue accumulating more candidates
and only error or mark covered=false after all candidates are exhausted. Ensure
you update the variables used in the Phase 3 check to reflect the extended
prefix and keep the existing semantics for setting covered and returning an
error when no prefix passes Phase 3.
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  • Create a new PR with the fixes

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Code Review

PR fixes the original Σ inputs == Σ outputs bug, but introduces three new protocol violations. The selector reasons about fee headroom in DIP-17 insertion order while the chain applies DeductFromInput(i) over BTreeMap key order — combined with dropping/draining tail inputs, this leaves the actual fee-bearing input with no remaining balance. The trim can also produce inputs below min_input_amount (100_000). The new tests assert only the structural invariant and would not catch any of these regressions.

Reviewed commit: aaf8be7

🔴 2 blocking | 🟡 1 suggestion(s) | 💬 2 nitpick(s)

🤖 Prompt for all review comments with AI agents
These findings are from an automated code review. Verify each finding against the current code and only fix it if needed.

In `packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs`:
- [BLOCKING] lines 321-365: Selector reserves fee headroom in insertion order, but the protocol charges DeductFromInput(0) against the BTreeMap-first input
  `select_inputs` keeps `chosen` in insertion (DIP-17) order and consumes from front to back, fully draining every input except the last to reach exactly `total_output`. It returns a `BTreeMap`, however, and the on-chain validator resolves `DeductFromInput(index)` via `remaining_balances.iter().nth(index)` (verified at `rs-dpp/.../state_transition_estimated_fee_validation.rs:48-69`), i.e. against BTreeMap key order — the lex-smallest selected address.

When the BTreeMap-first address is not the same as the insertion-order tail, all fee headroom ends up on the wrong input. The new test `two_input_selection_trims_only_the_last` demonstrates the failure mode directly: `addr_a = [0x01;20]` (BTreeMap key 0) is consumed for its full 20M balance — remaining = 0; `addr_b` keeps 40M of headroom. With `DeductFromInput(0)` the protocol charges the fee to `addr_a`, which has 0 left, so `fee_fully_covered = false` and the transition is rejected with `AddressesNotEnoughFundsError` (`rs-drive-abci/.../validate_fees_of_event/v0/mod.rs:209-224`).

The `fee_only_tail_input_does_not_inflate_input_sum` test exposes the same root cause via dropping rather than draining: `addr_a` has `total_output + 1` and is consumed for `total_output`, leaving 1 credit of remaining balance on the only returned input — far below any realistic transfer fee. The aggregate guarantee `Σ remaining ≥ fee` is irrelevant because the protocol charges the fee from one specific input, not the aggregate.

The helper must guarantee that the input the protocol will actually charge (BTreeMap-first when `fee_strategy = [DeductFromInput(0)]`) retains at least `estimated_fee` of remaining balance after consumption. Practical options: (a) compute the BTreeMap-first selected address up front and direct the trim residue to it, leaving headroom there; (b) restrict consumption on the fee-target input to `balance − estimated_fee`. The unit tests need to assert remaining balances after consumption, not just `Σ values == total_output`, to catch this class of bug.
- [BLOCKING] lines 351-365: Trimmed tail input can fall below `min_input_amount`, causing structural rejection
  The trim sets `consumed = (*bal).min(remaining)` per input, with no lower bound. The transfer validator rejects any input below `platform_version.dpp.state_transitions.address_funds.min_input_amount` (currently 100_000) with `InputBelowMinimumError` (`rs-dpp/.../address_funds_transfer_transition/v0/state_transition_validation.rs:146-167`).

A perfectly normal multi-input scenario triggers this: candidates A=5M, B=100M with `total_output = 5_050_000` yields `{A: 5_000_000, B: 50_000}`, and 50_000 < 100_000. Or two 100k inputs funding a 150k output: `{first: 100_000, second: 50_000}` — also rejected. None of the new tests exercise this boundary.

Fix options: filter candidates with `balance >= min_input_amount` at the call site and either skip a tail that would trim below the minimum (rolling residue back into a prior input) or refuse to add a candidate whose post-trim consumption would violate the limit. The helper aims to encode protocol correctness, so this should be enforced inside `select_inputs` rather than left to the validator.
- [SUGGESTION] lines 412-539: Tests assert the input-sum invariant only, not full state-transition validation
  `single_input_oversized_balance_trims_to_output_amount`, `two_input_selection_trims_only_the_last`, and `fee_only_tail_input_does_not_inflate_input_sum` all assert only that `Σ values == total_output`. They never assemble the result into an `AddressFundsTransferTransition` and run it through `validate_structure` + the fee-validation pipeline. As a result they pass on inputs maps that the on-chain validator deterministically rejects (see the two blocking findings above). The dpp validators are pure and don't need a live node — wiring an integration assertion into these tests would catch both classes of regression and is the right substitute for the still-pending testnet rerun referenced in the PR description.

Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
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Code Review

The DeductFromInput(0) headroom bug from the prior review is fixed: the selector now targets the BTreeMap-first input via lex-smallest selection, and the new pre_fix_buggy_selector_output_is_rejected_by_protocol_fee_deduction test exercises dpp's actual fee-deduction path. Two prior blockers remain reachable on the current head, however: Phase 4's distribution across non-fee-target inputs has no min_input_amount floor, and the public-API fallback for fee strategies other than [DeductFromInput(0)] produces input maps the validator deterministically rejects.

Reviewed commit: 60f7850

🔴 2 blocking | 🟡 1 suggestion(s) | 💬 2 nitpick(s)

🤖 Prompt for all review comments with AI agents
These findings are from an automated code review. Verify each finding against the current code and only fix it if needed.

In `packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs`:
- [BLOCKING] lines 504-521: Non-fee-target inputs can still be trimmed below `min_input_amount`
  Phase 3 pins `fee_target_min ≥ min_input_amount` (line 484), but Phase 4 then distributes `total_output − fee_target_consumed` across the non-fee-target prefix entries with `let consumed = (*bal).min(remaining)` and inserts any positive value (lines 516-520) — there is no per-input lower bound. The validator at `packages/rs-dpp/src/state_transition/state_transitions/address_funds/address_funds_transfer_transition/v0/state_transition_validation.rs:157-167` iterates `self.inputs.values()` and rejects ANY input below `min_input_amount` (100_000) with `InputBelowMinimumError`.

A construction that survives Phase 1 and Phase 3 but trips the validator:
- candidates after balance-desc sort: `[(addr_X=0x01, 1_000_000), (addr_Y=0x02, 30_000)]`
- `total_output = 950_000`, `min_input_amount = 100_000`
- Phase 1 needs both inputs (e.g. `fee_for_1 = 60_000` → 1_000_000 < 1_010_000; `fee_for_2 = 80_000` → 1_030_000 ≥ 1_030_000 ✓)
- `fee_target = addr_X`, `fee_target_max = 920_000`, `other_total = 30_000`, `fee_target_min = max(100_000, 920_000) = 920_000` — 920_000 ≤ 920_000 ✓
- Phase 4: `remaining = 30_000` → `addr_Y` inserted as 30_000 < 100_000 → rejected.

Fix options: filter candidates with `balance < min_input_amount` at the call site; refuse to insert a non-fee-target consumption that would land below the minimum (rolling residue back to the fee target, which already has remaining headroom); or bail out with a descriptive error. The existing `fee_headroom_violation_errors` test exercises only the fee-target min-input path; an analogous test for the tail input would catch this.
- [BLOCKING] lines 442-454: Fallback path is reachable via public API and produces protocol-invalid input maps
  `transfer()` (line 31) is `pub` and accepts an arbitrary `fee_strategy: AddressFundsFeeStrategy` from any caller. With `InputSelection::Auto`, this routes through `select_inputs()`, which only implements protocol-correct logic for the exact shape `[DeductFromInput(0)]` (line 437-440). For every other strategy, lines 442-453 fall back to a front-consume distribution that guarantees only `Σ inputs == total_output` and ignores both fee-target headroom and `min_input_amount`.

Reachable failure: with `fee_strategy = [DeductFromInput(1)]`, candidates `[(addr_b, 20M), (addr_a, 50M)]` where `addr_a < addr_b`, and `total_output = 30M`, the fallback returns `{addr_b: 20M, addr_a: 10M}`. The protocol resolves `DeductFromInput(i)` against BTreeMap key order (`packages/rs-dpp/src/address_funds/fee_strategy/.../v0/mod.rs`), so index 1 points at `addr_b`, which is fully drained — fee deduction fails exactly like the original bug. `ReduceOutput(...)` strategies can produce structurally invalid trailing inputs for the same reason.

The doc on lines 371-375 acknowledges this as 'must be revisited if [strategy] changes', but the public API surface is wide open today. Either constrain the strategy at the entry point, return an explicit `Err` for unsupported shapes, or extend the fee-target/min-input logic to general strategies. Returning a known-suspect map silently is the riskier option — it forces a future caller to stumble into the same protocol rejection that motivated this PR.
- [SUGGESTION] lines 484-545: `total_output < min_input_amount` falls through to misleading 'Internal selection error'
  When `total_output < min_input_amount` (e.g. caller asks to transfer 50_000 credits with min_input=100_000), the 1-input path computes `fee_target_min = max(min_input_amount, total_output) = 100_000 > total_output`, so `selected = {addr: 100_000}` and `input_sum = 100_000 ≠ total_output`. Phase 4's loop runs once with `remaining = total_output.saturating_sub(100_000) = 0`, then the flow trips the `debug_assert_eq!` at line 527 in debug builds and falls through to the line-538 'Internal selection error' branch in release.

The protocol disallows any transfer with `total_output < min_input_amount` (no input set can satisfy both `Σ inputs == total_output` and per-input `≥ min_input_amount`). This deserves an early, descriptive error like 'Transfer amount X below minimum Y' rather than the internal-error path that's documented as 'should never trip'. Add an early check at the top of `select_inputs` (or in the `transfer` entry-point on `outputs.values().sum()`).

Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
…egy, retry on Phase 3 fail

Addresses the second wave of review findings on PR #3554:

1. [BLOCKING] Phase 4 distribution no longer produces inputs below
   `min_input_amount`. `auto_select_inputs` now filters candidates
   with `balance < min_input_amount` upfront — they cannot legally
   appear in the inputs map. In Phase 4, when a non-fee-target
   tail entry would consume less than `min_input_amount`, the
   residue rolls back into the fee target's consumption (which has
   surplus headroom by construction). Returns a descriptive error
   if rollback would violate the fee-target headroom invariant.

2. [BLOCKING] `transfer()` rejects unsupported `fee_strategy`
   shapes for `InputSelection::Auto`. Auto-select currently only
   implements protocol-correct logic for `[DeductFromInput(0)]`;
   any other strategy returns `PlatformWalletError::AddressOperation`
   with a clear message redirecting callers to
   `InputSelection::Explicit`. Explicit paths still accept
   arbitrary strategies (caller's responsibility).

3. [BLOCKING] When Phase 3 (`fee_target_min > fee_target_max`) fails
   in `select_inputs`, the algorithm now extends the prefix with the
   next candidate and retries instead of erroring out. Larger
   prefixes may yield a different lex-smallest fee target with
   sufficient headroom. Errors out only when candidates are
   exhausted and no covering prefix is feasible.

4. [SUGGESTION] `select_inputs` returns an early descriptive error
   when `total_output < min_input_amount` — the protocol forbids
   this regardless of input shape, so an explicit error beats the
   internal "should never trip" branch that some callers were
   reaching.

5. [SUGGESTION] Existing selector tests now also build a minimal
   `AddressFundsTransferTransitionV0` and run `validate_structure`,
   asserting protocol-level validity in addition to the
   `Σ inputs == total_output` invariant. Catches future regressions
   without needing a live node.

Coderabbit findings DUuz (#3554), DUu1 (#3554), E5L5 (#3554),
thepastaclaw findings F9fo, GMHz, GMH5, GMH_, F9fv addressed.
Outdated F9fk references the renamed test from before 9ea9e70.
Nitpicks F9fz/GMID/F9f5/GMIH deferred (unreachable / low value).

Verification:
- cargo check --tests -p platform-wallet                  OK
- cargo clippy --tests -p platform-wallet -- -D warnings  OK
- cargo fmt -p platform-wallet                            OK
- cargo test -p platform-wallet --lib                     121/121

Co-Authored-By: Claudius the Magnificent <noreply@anthropic.com>
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🧹 Nitpick comments (1)
packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs (1)

607-631: Phase 5 invariant checks are partially release-protected.

The debug_assert statements at lines 611-624 verify critical protocol invariants:

  1. Σ inputs == total_output — also checked in release at line 626 ✓
  2. Fee target is BTreeMap index-0 (lex-smallest)
  3. Fee target retains ≥ estimated_fee remaining balance
  4. Every input ≥ min_input_amount

Invariants 2-4 are only asserted in debug builds. If any of these fail in release (due to a future regression in Phase 1-4 logic), the transition would be submitted and rejected by the protocol layer rather than caught here.

Given the algorithm's structure and test coverage, these should never trip. However, promoting invariant 3 (the fee headroom check) to a release-mode error would provide defense-in-depth for the exact bug this PR fixes.

♻️ Optional: Add release-mode check for fee headroom
     if input_sum != total_output {
         return Err(PlatformWalletError::AddressOperation(format!(
             "Internal selection error: Σ inputs ({}) != total_output ({})",
             input_sum, total_output
         )));
     }
+
+    let fee_target_remaining = fee_target_balance.saturating_sub(fee_target_consumed);
+    if fee_target_remaining < estimated_fee {
+        return Err(PlatformWalletError::AddressOperation(format!(
+            "Internal selection error: fee target {} remaining {} < estimated fee {}",
+            format_address(&fee_target_addr),
+            fee_target_remaining,
+            estimated_fee,
+        )));
+    }
 
     Ok(selected)
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.

In `@packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs` around
lines 607 - 631, The fee-headroom check currently uses debug_assert! on
fee_target_balance.saturating_sub(fee_target_consumed) >= estimated_fee, which
is only active in debug builds; replace that debug-only assertion with a
release-mode runtime check inside the same scope (where selected,
fee_target_balance, fee_target_consumed and estimated_fee are available) so that
if the condition fails you return
Err(PlatformWalletError::AddressOperation(...)) with a clear message including
the computed headroom and required estimated_fee; keep the other debug_asserts
as-is and ensure the new check mirrors the existing error style used for
input_sum != total_output.
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs`:
- Around line 607-631: The fee-headroom check currently uses debug_assert! on
fee_target_balance.saturating_sub(fee_target_consumed) >= estimated_fee, which
is only active in debug builds; replace that debug-only assertion with a
release-mode runtime check inside the same scope (where selected,
fee_target_balance, fee_target_consumed and estimated_fee are available) so that
if the condition fails you return
Err(PlatformWalletError::AddressOperation(...)) with a clear message including
the computed headroom and required estimated_fee; keep the other debug_asserts
as-is and ensure the new check mirrors the existing error style used for
input_sum != total_output.

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Run ID: e663ab0e-42e2-48de-b207-cd8e4fa9740b

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Reviewing files that changed from the base of the PR and between 60f7850 and 9ff937f.

📒 Files selected for processing (1)
  • packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs

lklimek and others added 6 commits April 28, 2026 16:33
…allet changes

Adds `rs-platform-wallet` as a filter entry in
`.github/package-filters/rs-packages-no-workflows.yml`. Without this,
crate-only changes under `packages/rs-platform-wallet/` evaluate to
`rs-packages = '[]'` and the `rs-workspace-tests` job in
`.github/workflows/tests.yml` gates off — meaning the crate's unit
tests never run in CI when only that crate is touched.

This gap surfaced on PR #3554 itself: five commits, 121 unit tests,
none of them executed by `Rust workspace tests` (all reported as
SKIPPED). Local `cargo test -p platform-wallet --lib` was the only
validation. Reviewers seeing "all green" could miss that the actual
Rust validation was skipped.

The filter entry mirrors the existing pattern: list the crate path
and inherit the SDK alias (`*sdk`) so transitive SDK changes also
trigger workspace tests for the wallet, matching how `wasm-sdk` and
`rs-sdk-ffi` are wired.

Co-Authored-By: Claudius the Magnificent <noreply@anthropic.com>
…now run)

The CI filter addition in 79c2b28 made `Rust workspace tests` run
on `rs-platform-wallet` for the first time in a while, surfacing
three pre-existing breaks that the silently-skipped pipeline had
been accumulating:

1. `src/changeset/core_bridge.rs` (`build_core_changeset`) —
   `field_reassign_with_default` lint. `let mut cs =
   CoreChangeSet::default(); cs.new_utxos = ...; cs.spent_utxos = ...;`
   replaced with a struct literal carrying the derived values plus
   `..CoreChangeSet::default()` for forward-compat fields.

2. `src/wallet/apply.rs:316` — `let_unit_value` lint.
   `WalletInfoInterface::update_balance` returns `()`; the `let _ =
   ...` discards a unit value. Calling the method directly is the
   intended shape.

3. `tests/spv_sync.rs:74-78` — stale field access. The integration
   test still walked `core.chain.synced_height` even though
   `CoreChangeSet` was flattened (see existing rustdoc on
   `synced_height` direct field). Replaced with
   `core.synced_height` directly.

None of these are bugs — clippy hardening and a stale test field
that `cargo test --lib` never compiled. Verified:

- `cargo clippy --workspace --tests -- -D warnings` clean
- `cargo clippy -p platform-wallet --tests -- -D warnings` clean
- `cargo test -p platform-wallet --lib` 121/121

Co-Authored-By: Claudius the Magnificent <noreply@anthropic.com>
… work

Apply claudius:coding-best-practices rules: length cap (<=2 preferred,
3 mediocre), present-state only (no Wave/PR-number history), two-tier
(strict for internal, liberal for public API rustdoc).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…o-select

Extends transfer() / auto_select_inputs to accept [ReduceOutput(0)] in addition
to [DeductFromInput(0)]. Output 0 absorbs the fee, so input selection skips the
fee-headroom reservation. Σ inputs == Σ outputs invariant preserved via last-
input trim.

5 new tests in auto_select_tests cover happy path, multi-input trim, multi-
output isolation, output-too-small error, and structural validation.

Resolves PR #3549 thread r-aCky's production prerequisite.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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codecov Bot commented Apr 29, 2026

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.16%. Comparing base (31e8af2) to head (4965e42).
⚠️ Report is 2 commits behind head on v3.1-dev.

Additional details and impacted files
@@             Coverage Diff              @@
##           v3.1-dev    #3554      +/-   ##
============================================
- Coverage     87.16%   87.16%   -0.01%     
============================================
  Files          2607     2607              
  Lines        319420   319420              
============================================
- Hits         278413   278412       -1     
- Misses        41007    41008       +1     
Components Coverage Δ
dpp 87.67% <ø> (-0.01%) ⬇️
drive 85.95% <ø> (ø)
drive-abci 89.60% <ø> (ø)
sdk ∅ <ø> (∅)
dapi-client ∅ <ø> (∅)
platform-version ∅ <ø> (∅)
platform-value 92.17% <ø> (ø)
platform-wallet ∅ <ø> (∅)
drive-proof-verifier 49.16% <ø> (ø)
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…allet-auto-select-inputs

# Conflicts:
#	packages/rs-platform-wallet/src/changeset/core_bridge.rs
@lklimek lklimek added the ready for final review Ready for the final review. If AI was involved in producing this PR, it has already had a reviewer. label Apr 30, 2026
lklimek and others added 2 commits April 30, 2026 10:08
…educeOutput Phase 4

Annotates `select_inputs_reduce_output`'s Phase 4 fee-headroom check
to document the known dpp-layer bug (platform #3040) where
`estimate_min_fee` models only the static state_transition_min_fees
floor and excludes storage + processing costs. For small `output[0]`,
the auto-selector greenlights selections that then fail on-chain with
AddressesNotEnoughFundsError. Comment-only — no behaviour change.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Code Review

Verified the reported issues against the checked-out head 6c8c5d955e2fb3b896be90fe4e27060a0b1df72d. Four Codex findings are real on this SHA: the SPV shutdown path has a lock-order deadlock, the Swift explicit-change wrapper still mis-targets ReduceOutput, and two wallet/FFI paths still persist or accept ambiguous address state. No CodeRabbit comments were provided for this run, and I did not confirm any resolved prior findings.

🔴 2 blocking | 🟡 2 suggestion(s)

4 additional finding(s) omitted (not in diff).

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Code Review details for review 4356806897

Correction: GitHub accepted review 4356806897, but its body omitted the out-of-diff findings. Full details for the same checked-out head 6c8c5d955e2fb3b896be90fe4e27060a0b1df72d. Four findings are valid on this SHA: one new blocking issue in the latest delta, plus all three prior findings from ceb4fc87 remain STILL VALID and are carried forward below. No prior finding was verified as fixed, outdated, or intentionally deferred.

🔴 2 blocking | 🟡 2 suggestion(s)

Reviewed commit: 6c8c5d9

New finding in latest delta

🔴 blocking: `SpvRuntime::run()` holds the client read lock until `client.run()` returns, so `stop()` cannot ever acquire the write lock it needs

packages/rs-platform-wallet/src/spv/runtime.rs (lines 138-159)

run() reads self.client, borrows the inner client, and then awaits client.run() while the RwLockReadGuard is still alive. stop() is the only public shutdown path, and it starts by taking self.client.write().await before calling c.stop(). Once the sync loop is running, shutdown makes no forward progress: stop() waits on the write lock, while run() keeps the read lock until client.run() exits, and client.run() is exactly what stop() must terminate. The same inversion affects both the Rust test path in tests/spv_sync.rs and the FFI stop entry point in packages/rs-platform-wallet-ffi/src/spv.rs.

Carried-forward prior findings from ceb4fc87 — STILL VALID

🔴 blocking: Swift explicit-change transfers still choose `ReduceOutput` by Swift array index even though Rust/DPP reorders outputs by address

packages/swift-sdk/Sources/SwiftDashSDK/PlatformWallet/ManagedPlatformAddressWallet.swift (lines 296-327)

This wrapper appends the change output last and sends FeeStrategyStepFFI(step_type: 1, index: ffiOutputs.count - 1), assuming the fee target is the last Swift output. That assumption is false on the Rust side. platform_address_wallet_transfer() parses the array, PlatformAddressWallet::transfer() immediately canonicalizes outputs into a BTreeMap, and the SDK/DPP path interprets ReduceOutput(0)-style indexes over that canonical order, not Swift insertion order. The Rust wallet already documents this behavior and only protects it in transfer_with_change_address(), but this Swift wrapper still calls the plain platform_address_wallet_transfer(...) entry point. If the chosen change address sorts before a recipient, the chain deducts the fee from a different output than the UI presented, so the wallet can underpay a recipient while claiming the fee came only from change.

🟡 suggestion: Post-transfer persistence still records foreign recipient addresses as wallet-owned account rows

packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs (lines 121-154)

Sdk::transfer_address_funds*() returns AddressInfos for the union of input and output addresses, and this loop persists every returned P2pkh row. The code updates set_address_credit_balance(...) before proving the address belongs to the managed account, then fabricates address_index = 0 with unwrap_or(0) when the address is not in the account’s derivation pool. Those rows are later replayed through insert_persisted_entry() and initialize_from_persisted() as if they were wallet-owned state. One transfer to an external recipient is therefore enough to poison persisted account state with an address the wallet cannot sign for.

💡 Suggested change
                for (addr, maybe_info) in address_infos.iter() {
                    let PlatformAddress::P2pkh(hash) = addr else {
                        continue;
                    };
                    let p2pkh = PlatformP2PKHAddress::new(*hash);
                    let Some(address_index) = account
                        .addresses
                        .addresses
                        .iter()
                        .find_map(|(&idx, info)| {
                            PlatformP2PKHAddress::from_address(&info.address)
                                .ok()
                                .filter(|found| *found == p2pkh)
                                .map(|_| idx)
                        })
                    else {
                        continue;
                    };
                    let funds = match maybe_info {
                        Some(ai) => dash_sdk::platform::address_sync::AddressFunds {
                            balance: ai.balance,
                            nonce: ai.nonce,
                        },
                        None => dash_sdk::platform::address_sync::AddressFunds {
                            balance: 0,
                            nonce: 0,
                        },
                    };
                    account.set_address_credit_balance(p2pkh, funds.balance, key_source.as_ref());
                    cs.addresses.push(crate::PlatformAddressBalanceEntry {
                        wallet_id: self.wallet_id,
                        account_index,
                        address_index,
                        address: p2pkh,
                        funds,
                    });
                }
🟡 suggestion: `parse_outputs()` still silently overwrites duplicate destination rows at the public FFI boundary

packages/rs-platform-wallet-ffi/src/platform_address_types.rs (lines 203-205)

parse_outputs() feeds the caller-supplied array into an IndexMap with map.insert(addr, entry.balance), so a repeated PlatformAddress silently replaces the earlier amount instead of rejecting the request. Rust-native callers cannot construct duplicate keys, which makes this FFI parser the last boundary that can reject an ambiguous output set before Rust signs and broadcasts it. The Swift wrapper now rejects duplicate recipient hashes for its own call path, but this function is still exported through the public C ABI and remains reachable by other FFI callers.

💡 Suggested change
        for entry in std::slice::from_raw_parts(ptr, count) {
            let addr = PlatformAddress::try_from(entry.address)?;
            if map.contains_key(&addr) {
                return Err("Duplicate output address");
            }
            map.insert(addr, entry.balance);
        }

Prior-finding reconciliation

  • STILL VALID: Swift explicit-change ReduceOutput index mismatch.
  • STILL VALID: transfer persistence records foreign recipient addresses as wallet-owned state.
  • STILL VALID: FFI parse_outputs() silently coalesces duplicate destination rows.
  • FIXED / OUTDATED / INTENTIONALLY DEFERRED: none verified.

lklimek and others added 2 commits May 25, 2026 15:11
…ion addresses (PR #3554 CMT-003)

`parse_outputs` previously kept inserting into the output `IndexMap`
without checking for collisions, so a duplicate `AddressBalanceEntryFFI`
silently overwrote the earlier entry — the wallet would still sum every
output toward change calculation, leaving the transition misbalanced.

The Swift wrapper guards against this today (CMT-001 follow-up tracked
in #3738), but the Rust FFI is the authoritative gate. Reject duplicates
explicitly, naming the offending address hash so the caller can identify
which output collided.

Switched the return type to `Result<_, String>` and added the matching
`From<String> for PlatformWalletFFIResult` impl — the only caller goes
through `unwrap_result_or_return!` which already routes via `.into()`,
so the ripple is one new impl and one signature change.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
…sistence (PR #3554 CMT-002)

`transfer_address_funds` returns address info for the full
`inputs ∪ outputs` set, including external recipients the wallet does
not own. The persistence loop in `transfer` called
`set_address_credit_balance` on every returned `P2pkh` and fell back to
`address_index = 0` when the address was not in the derived pool —
persisting external recipients under a fabricated derivation index that
would poison the account's address map on restore.

Hoist the derived-pool lookup to the top of the loop, skip non-owned
addresses before touching the account, and drop the `.unwrap_or(0)`
fallback. Factor the filter + entry construction into a pure helper
`build_transfer_persistence_entries` so the invariant is unit-testable
without spinning up an SDK + wallet manager.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@Claudius-Maginificent
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@thepastaclaw — addressing your three carried-forward findings from the 2026-05-22 re-validation.

CMT-002 — Transfer persistence filters external recipients (`1fba51c1`)
Refactored `transfer.rs` persistence loop to skip addresses not in the wallet's derived-address pool. The `.unwrap_or(0)` fallback that persisted external recipients under `address_index = 0` is gone. Factored the filter+entry build into pure helper `build_transfer_persistence_entries`. Two new tests: `persistence_filter_drops_external_recipients` (asserts a transfer-to-external-recipient produces no persisted entry for the recipient), `persistence_filter_treats_missing_info_as_zero`.

CMT-003 — `parse_outputs` rejects duplicates (`2eab4f7c`)
Switched `parse_outputs` to `Result<_, String>` so the error message can name the offending address. Returns `Err("Duplicate output address: ")` on collision. Single caller (`transfer.rs:41`) routes via `unwrap_result_or_return!` + `.into()` — no caller code changes. One new `From for PlatformWalletFFIResult` impl. Used `hex::encode` instead of `Debug` because `PlatformAddress::P2pkh([u8;20])`'s default Debug is a decimal byte array (unreadable). 2 new unit tests.

CMT-001 (Swift `ReduceOutput(insertion-index)` BLOCKING) — deferred to dedicated follow-up issue #3738, assigned to @shumkov. The buggy code (`changeIndex = ffiOutputs.count - 1`) is preexisting from #3626; PR #3554 doesn't touch `ManagedPlatformAddressWallet.swift` (zero diff against base). Fixing it inside #3554 would be scope creep on already-merged Swift SDK territory. The issue carries the BLOCKING severity tag and the two fix options you outlined (lex-sort outputs in Swift, OR route through `transfer_with_change_address`).

Validations: `cargo fmt --check` clean, `clippy --tests -- -D warnings` clean, `cargo test --lib` 146 passed (platform-wallet) / 80 passed (platform-wallet-ffi).

🤖 Co-authored by Claudius the Magnificent AI Agent

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One remaining non-blocking concern I still see in the exact head:

auto_select_inputs() still builds its candidate set from a read-only platform-address balance snapshot, with no reservation or pre-broadcast revalidation step. The code itself calls this out around packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs:292-296:

// TODO(QA-007): pre-existing read-snapshot vs broadcast race; new
// headroom math leans harder on snapshot. Hold guard across
// snapshot+broadcast+update, or re-validate headroom right before
// broadcast.

Why it matters: a concurrent platform-address spend can invalidate the selected balances after this snapshot is taken, so the transfer path can still build from stale input state and fail later at broadcast/validation time. The new headroom logic depends more heavily on that snapshot.

Suggested fix: add a reservation/revalidation step for platform-address inputs before broadcasting, or hold the relevant wallet/account state lock across selection and transition submission.

The earlier concrete issues I checked look fixed in this head: external-recipient persistence poisoning, duplicate FFI output-address overwrites, and typed no-selectable-input errors.

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lklimek commented May 25, 2026

This is a pre-existing issue,

auto_select_inputs() still builds its candidate set from a read-only platform-address balance snapshot, with no reservation or pre-broadcast revalidation step.

This is a pre-existing issue, out of scope.

@lklimek lklimek added the ready for final review Ready for the final review. If AI was involved in producing this PR, it has already had a reviewer. label May 25, 2026
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Code Review

I confirmed three real issues on head 1fba51c16c4182a0d8cb00d631a4c9883f545500. Two are blocking regressions that remain unchanged: SPV shutdown can deadlock, and the Swift transfer wrapper still computes ReduceOutput against Swift insertion order even though Rust/DPP interpret that index in lexicographic address order. I also confirmed that the duplicate-output parser bug and the foreign-recipient persistence bug are fixed in this SHA.

🔴 2 blocking | 🟡 1 suggestion(s)

3 additional finding(s) omitted (not in diff).

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Code Review details for review 4357135284

Correction: the review body GitHub accepted omitted the out-of-diff finding details. I confirmed three real issues on head 1fba51c16c4182a0d8cb00d631a4c9883f545500. Two are blocking regressions that remain unchanged: SPV shutdown can deadlock, and the Swift transfer wrapper still computes ReduceOutput against Swift insertion order even though Rust/DPP interpret that index in lexicographic address order. I also confirmed that the duplicate-output parser bug and the foreign-recipient persistence bug are fixed in this SHA.

🔴 2 blocking | 🟡 1 suggestion(s)

Prior findings resolved on this SHA

  • Post-transfer persistence still records foreign recipient addresses as wallet-owned account rows — Fixed in this SHA. transfer() now builds an owned address lookup and only persists entries returned by build_transfer_persistence_entries(...), which skips addresses outside the wallet's derived pool (packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs:121-149 and 416-451).
  • parse_outputs() still silently overwrites duplicate destination rows at the public FFI boundary — Fixed in this SHA. parse_outputs() now rejects duplicate destination addresses and the unit test parse_outputs_rejects_duplicate_destination_address covers that behavior (packages/rs-platform-wallet-ffi/src/platform_address_types.rs:194-214 and 430-467).

Verified findings

blocking: SPV shutdown deadlocks because `run()` holds the read lock for the entire sync loop while `stop()` requires the write lock

Location: packages/rs-platform-wallet/src/spv/runtime.rs:138-159

SpvRuntime::run() acquires self.client.read().await and keeps that guard alive across client.run().await. SpvRuntime::stop() is the only shutdown path, but it starts by acquiring self.client.write().await before it can call c.stop(). That creates a lock inversion: once the background sync loop is running, stop() cannot obtain the write lock until run() returns, and run() cannot return until stop() signals the client to stop. The FFI stop entry point in packages/rs-platform-wallet-ffi/src/spv.rs:269-275 routes directly into this method, so foreign callers can hang indefinitely as well.

blocking: Swift explicit-change transfers target `ReduceOutput` by Swift array index even though Rust canonicalizes outputs by address before applying the fee strategy

Location: packages/swift-sdk/Sources/SwiftDashSDK/PlatformWallet/ManagedPlatformAddressWallet.swift:296-316

This wrapper appends the change row last and then sends FeeStrategyStepFFI(step_type: 1, index: ffiOutputs.count - 1), assuming the fee target is the last Swift output. That assumption is false in the called Rust path: platform_address_wallet_transfer() parses the array, then PlatformAddressWallet::transfer() converts outputs into a BTreeMap (packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs:27-48), and its own docs state that ReduceOutput(0) refers to the lexicographically smallest output, not insertion order. If the chosen change address sorts before a recipient, the fee is deducted from a different output than Swift presented to the caller, so the broadcast transfer can underpay a recipient while claiming the fee came only from change. The new Rust-side guard in transfer_with_change_address() does not protect this path because the Swift wrapper still calls the plain platform_address_wallet_transfer(...) FFI entry point.

suggestion: The public FFI explicit-input parsers still silently overwrite duplicate rows instead of rejecting ambiguous caller input

Location: packages/rs-platform-wallet-ffi/src/platform_address_types.rs:129-162

Both parse_explicit_inputs() and parse_explicit_inputs_with_nonces() build a BTreeMap with unconditional map.insert(...). If a foreign caller passes the same address twice, the later row silently replaces the earlier balance, and in the nonce-bearing form it also replaces the earlier nonce. This is reachable from public FFI through parse_input_selection() in packages/rs-platform-wallet-ffi/src/platform_addresses/mod.rs:32-58 and is used by both transfer and withdrawal entry points. Rust-native callers cannot construct duplicate keys in these maps, so the FFI parser is the last trust boundary that can reject this ambiguity before Rust signs and broadcasts a different effective input set than the caller supplied or displayed.

🤖 Prompt for all review comments with AI agents
These findings are from an automated code review. Verify each finding against the current code and only fix it if needed.

- [BLOCKING] In `packages/rs-platform-wallet/src/spv/runtime.rs`:138-159: SPV shutdown deadlocks because `run()` holds the read lock for the entire sync loop while `stop()` requires the write lock
  `SpvRuntime::run()` acquires `self.client.read().await` and keeps that guard alive across `client.run().await`. `SpvRuntime::stop()` is the only shutdown path, but it starts by acquiring `self.client.write().await` before it can call `c.stop()`. That creates a lock inversion: once the background sync loop is running, `stop()` cannot obtain the write lock until `run()` returns, and `run()` cannot return until `stop()` signals the client to stop. The FFI stop entry point in `packages/rs-platform-wallet-ffi/src/spv.rs:269-275` routes directly into this method, so foreign callers can hang indefinitely as well.
- [BLOCKING] In `packages/swift-sdk/Sources/SwiftDashSDK/PlatformWallet/ManagedPlatformAddressWallet.swift`:296-316: Swift explicit-change transfers target `ReduceOutput` by Swift array index even though Rust canonicalizes outputs by address before applying the fee strategy
  This wrapper appends the change row last and then sends `FeeStrategyStepFFI(step_type: 1, index: ffiOutputs.count - 1)`, assuming the fee target is the last Swift output. That assumption is false in the called Rust path: `platform_address_wallet_transfer()` parses the array, then `PlatformAddressWallet::transfer()` converts outputs into a `BTreeMap` (`packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs:27-48`), and its own docs state that `ReduceOutput(0)` refers to the lexicographically smallest output, not insertion order. If the chosen change address sorts before a recipient, the fee is deducted from a different output than Swift presented to the caller, so the broadcast transfer can underpay a recipient while claiming the fee came only from change. The new Rust-side guard in `transfer_with_change_address()` does not protect this path because the Swift wrapper still calls the plain `platform_address_wallet_transfer(...)` FFI entry point.
- [SUGGESTION] In `packages/rs-platform-wallet-ffi/src/platform_address_types.rs`:129-162: The public FFI explicit-input parsers still silently overwrite duplicate rows instead of rejecting ambiguous caller input
  Both `parse_explicit_inputs()` and `parse_explicit_inputs_with_nonces()` build a `BTreeMap` with unconditional `map.insert(...)`. If a foreign caller passes the same address twice, the later row silently replaces the earlier balance, and in the nonce-bearing form it also replaces the earlier nonce. This is reachable from public FFI through `parse_input_selection()` in `packages/rs-platform-wallet-ffi/src/platform_addresses/mod.rs:32-58` and is used by both transfer and withdrawal entry points. Rust-native callers cannot construct duplicate keys in these maps, so the FFI parser is the last trust boundary that can reject this ambiguity before Rust signs and broadcasts a different effective input set than the caller supplied or displayed.

@lklimek lklimek moved this to In review / testing in Platform team May 26, 2026
…allet-auto-select-inputs

# Conflicts:
#	packages/rs-platform-wallet-ffi/src/error.rs
#	packages/swift-sdk/Sources/SwiftDashSDK/PlatformWallet/PlatformWalletResult.swift
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Code Review

I verified the reported code paths on the checked-out head 911dffe76d9ea4dbf52d73d06eb5e2679d9445a5. All three reported behaviors are real in the current tree, but none are introduced or modified by this PR’s incremental merge: the actual diff from 1fba51c16c4182a0d8cb00d631a4c9883f545500 only touches FFI error-code mapping, identity-manager accessors, a Swift error enum mirror, and a DAPI trace log. Because these defects live in unchanged files and predate this delta, they should be tracked separately rather than block this PR.

Out-of-scope follow-up suggestions (4)

These are valid observations, but they are outside this PR's scope and should be handled in separate PRs/issues rather than blocking this review.

  • SPV runtime shutdown still has a read/write lock inversionpackages/rs-platform-wallet/src/spv/runtime.rs still holds self.client.read().await across client.run().await, while stop() still requires self.client.write().await before it can call c.stop(). That makes the hang reported by the agents a real bug on the current head, and the FFI stop entry point still routes into it via packages/rs-platform-wallet-ffi/src/spv.rs. However, none of those files changed in this PR delta, and git blame shows the relevant lines come from earlier commits outside PR #3554’s current changeset, so this should not block the auto-select/input-selection work here.
    • Follow-up: Create a separate fix PR that releases the client lock before awaiting client.run() or otherwise restructures shutdown so stop() can signal the running client without first acquiring the write lock.
  • Swift explicit-change transfer still mismatches Rust fee-target orderingpackages/swift-sdk/Sources/SwiftDashSDK/PlatformWallet/ManagedPlatformAddressWallet.swift still appends the change output last and emits ReduceOutput(lastIndex), while packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs still canonicalizes outputs into a BTreeMap and documents that ReduceOutput(0) is interpreted by lexicographic address order. That mismatch is a real integrity bug on the current head. But the affected Swift wrapper and Rust transfer code are unchanged in the diff being reviewed here, so it is outside this PR’s scope even though it remains worth fixing separately.
    • Follow-up: Create a separate PR that routes explicit-change transfers through an ABI that resolves the fee target by address, or enforces/derives the Rust-side canonical index instead of using the Swift array position.
  • FFI explicit-input parsers still silently overwrite duplicate rowspackages/rs-platform-wallet-ffi/src/platform_address_types.rs still uses unconditional map.insert(...) in both parse_explicit_inputs() and parse_explicit_inputs_with_nonces(), so duplicate caller-supplied addresses collapse silently. packages/rs-platform-wallet-ffi/src/platform_addresses/mod.rs still exposes those parsers on the public input-selection boundary, so the ambiguity is reachable. This is a valid trust-boundary hardening gap, but those parser files are unchanged in the reviewed delta, so it should be handled in a separate follow-up instead of blocking this PR.
    • Follow-up: Create a separate PR that rejects duplicate explicit-input addresses in both FFI parsers and adds coverage for the duplicate-row error path.
  • Auto-selection still has a documented snapshot-versus-broadcast racepackages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs still contains TODO QA-007 describing a pre-existing race between reading the wallet snapshot and broadcasting/updating state. The comment itself marks this as deferred, and the file is unchanged in the current incremental merge, so it is not an actionable review finding for this PR. It is still worth tracking because the newer headroom logic depends on that snapshot remaining valid until broadcast.
    • Follow-up: Create a separate PR or issue to hold the relevant wallet/account state across snapshot, broadcast, and update, or re-validate headroom immediately before signing and broadcast.

…ct duplicate input addresses (PR #3554 CMT-003)

Mirror of the parse_outputs hardening shipped in 2eab4f7 — both explicit-input
parsers previously called map.insert(addr, ...) unconditionally, so a duplicate
ExplicitInputFFI/ExplicitInputWithNonceFFI silently overwrote the earlier entry.
The wallet would then compute the input sum against an under-populated map,
leaving the resulting state transition misbalanced.

The Swift wrapper guards against this today, but Rust FFI is the authoritative
gate — reject explicitly, naming the offending address hash so the caller can
identify which input collided.

Switched return type to Result<_, String> matching the parse_outputs precedent;
no caller adjustments needed (unwrap_result_or_return! already routes through
.into() and the From<String> impl was added in 2eab4f7).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@Claudius-Maginificent
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Status update on the 2026-05-25T14:00 review @thepastaclaw

Finding Disposition Reference
CMT-001 SPV shutdown deadlock Defer — pre-existing Issue #3741, fix in flight: PR #3742
CMT-002 Swift ReduceOutput insertion-index Defer — pre-existing Issue #3738
CMT-003 parse_explicit_inputs[_with_nonces] duplicates Fixed Commit 302943ad4b

CMT-001 — SPV shutdown deadlock (defer)

Pre-existing v3.1-dev bug. The lock-inversion in runtime.rs:138-159 was introduced by PR #3730 (Borja Castellano / @ZocoLini, commit 9f3bfa3ca3, merged 2026-05-22), not by this PR. Filed as issue #3741 (priority: high, assigned @ZocoLini). Fix already in flight as PR #3742 (fix(platform-wallet): fix spv client deadlocking himself when trying to stop) — Closes #3741, approach: clone the inner SpvClient (Arc fields) so run() operates on its own clone without holding the read lock across the await. When #3742 merges to v3.1-dev, it cascades into this PR via the next merge-base. Same defer pattern we used for prior cycles.

CMT-002 — Swift ReduceOutput(insertion-index) underpayment (defer)

Pre-existing Swift-wrapper bug originating from merged PR #3626, not in this PR's diff. The wrapper appends change last and sends ReduceOutput(array.count - 1) assuming insertion-order semantics; Rust canonicalizes outputs into a BTreeMap resolved by lex address order. Filed as issue #3738 (assigned @llbartekll). The Swift surface lives outside this PR's rs-platform-wallet* scope. Same defer-to-issue path as the previous review cycle.

CMT-003 — parse_explicit_inputs[_with_nonces] duplicate rejection (fixed)

Fixed in commit 302943ad4b. Both parse_explicit_inputs and parse_explicit_inputs_with_nonces in packages/rs-platform-wallet-ffi/src/platform_address_types.rs now reject duplicate input addresses with a hex-encoded hash diagnostic, mirroring the parse_outputs precedent shipped earlier this cycle in commit 2eab4f7c. Two new unit tests pin the rejection:

  • parse_explicit_inputs_rejects_duplicate_input_address
  • parse_explicit_inputs_with_nonces_rejects_duplicate_input_address

Return type widened to Result<_, String>; zero caller ripple — unwrap_result_or_return! already routes through From<String> for PlatformWalletFFIResult (added in 2eab4f7c).

Other changes since the 14:00 review

Merge-base from v3.1-dev landed at commit 911dffe76d. Net effect: this PR absorbs #3651's FFI error-code consolidation. All three PlatformWalletError typed variants (OnlyOutputAddressesFunded, OnlyDustInputs, NoSpendableInputs) now route to a single FFI code ErrorNoSelectableInputs = 14; the dust-breadcrumb fields survive on the Rust enum and surface in the Display message string. Slot 13 is reserved as ErrorArithmeticOverflow (no producer yet).

Quality gates at HEAD 302943ad4b

  • cargo fmt --all — clean
  • cargo clippy --workspace --all-targets -- -D warnings — clean
  • cargo test -p platform-wallet --lib — 146 / 146
  • cargo test -p platform-wallet-ffi --lib — 83 / 83

0 unresolved inline review threads.

Ready for re-review.

🤖 Co-authored by Claudius the Magnificent AI Agent

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Code Review

I verified the checked-out head at 302943ad4b4fa7661ec4382a04c91d85c18161c0 and the reviewed delta from 911dffe76d9ea4dbf52d73d06eb5e2679d9445a5. The PR only changes packages/rs-platform-wallet-ffi/src/platform_address_types.rs, and that change is correct: both explicit-input parser paths now reject duplicate caller-supplied addresses and the new tests cover those error cases. I found no new in-scope defects introduced by this PR. A focused cargo test -p platform-wallet-ffi duplicate_input_address run could not complete in this environment because tenderdash-proto attempts to download Tenderdash sources during build.

Out-of-scope follow-up suggestions (3)

These are valid observations, but they are outside this PR's scope and should be handled in separate issues or author/maintainer-requested PRs rather than blocking this review.

  • SPV runtime shutdown still has a read/write lock inversionpackages/rs-platform-wallet/src/spv/runtime.rs:138-160 still holds self.client.read().await across client.run().await, while stop() begins by taking self.client.write().await before it can call c.stop(). If run() is active, stop() can block behind the write lock while the read guard remains held for the lifetime of the run loop, leaving the runtime vulnerable to a shutdown hang. This is outside PR #3554's scope because the delta only changes explicit-input parsing in packages/rs-platform-wallet-ffi/src/platform_address_types.rs.
    • Follow-up: Create a separate issue or author/maintainer-requested PR to let stop() signal shutdown without first waiting on the write lock, or to avoid holding the read guard across client.run().await.
  • Swift explicit-change transfers still target ReduceOutput by Swift array index while Rust canonicalizes outputs by addresspackages/swift-sdk/Sources/SwiftDashSDK/PlatformWallet/ManagedPlatformAddressWallet.swift:296-316 still appends the change output last and sends ReduceOutput(lastIndex) through platform_address_wallet_transfer(). That FFI entrypoint calls Rust transfer(), which canonicalizes outputs into a BTreeMap keyed by PlatformAddress before DPP interprets ReduceOutput(index); unlike Rust's separate transfer_with_change_address() helper, this path does not reject a lexicographically smaller change address. A change address that sorts before a recipient can therefore cause the on-chain fee target to differ from the Swift-visible target. This remains outside PR #3554 because none of the changed files touch the Swift wrapper or transfer bridge.
    • Follow-up: Create a separate issue or author/maintainer-requested PR to route Swift explicit-change transfers through a Rust API that resolves the fee target by canonical output identity, or to pre-validate that the change address cannot sort before the intended recipient outputs.
  • Auto-selection still has the documented snapshot-versus-broadcast racepackages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs:292-295 still carries TODO QA-007, and the code still reads wallet state under a snapshot before later broadcast and persistence steps. That race is real and the file explicitly documents it, but it predates this PR and the reviewed delta does not touch the transfer execution path.
    • Follow-up: Create a separate issue or author/maintainer-requested PR to hold the relevant state across snapshot plus broadcast, or to re-validate balances and fee headroom immediately before signing and broadcast.

…instead of IndexMap

IndexMap is not part of our official public API surface. Public `transfer`
and `transfer_with_change_address` now accept
`impl IntoIterator<Item = (PlatformAddress, Credits)>` and canonicalize
directly to BTreeMap at the public boundary — DPP's downstream contract
is already BTreeMap-keyed, so there is no intermediate IndexMap step.

No behavior change. FFI callers (which build IndexMap via parse_outputs)
compile unchanged — IndexMap implements IntoIterator. `BTreeMap` callers
now compile too, pinned by a new unit test
(`transfer_with_change_address_accepts_btreemap_outputs`) that reaches
the Auto+Some(change_addr) rejection arm via a BTreeMap input.

`transfer_with_change_address` previously collected `outputs_with_change`
back into IndexMap solely to satisfy `transfer`'s old parameter type;
that re-collection is now gone (BTreeMap is passed straight through).

Module-level `use indexmap::IndexMap` moved to `auto_select_tests` —
production code no longer references the type.

Internal helpers (`saturating_sum_credits`, `checked_sum_credits`,
`build_auto_select_candidates`, `detect_no_selectable_inputs`,
`validate_change_address`, `build_transfer_persistence_entries`) keep
their existing `IntoIterator` bounds — each performs a single iter walk
without random access, so a concrete map would only narrow the input
shape without simplifying the body.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@Claudius-Maginificent
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Policy iteration — public API no longer exposes IndexMap (commit ece54f9369)

Per maintainer guidance, IndexMap is not part of the official rs-platform-wallet public surface. Two public functions flipped:

- pub async fn transfer<S: Signer<PlatformAddress> + ...>(
-     ...,
-     outputs: IndexMap<PlatformAddress, Credits>,
-     ...
- ) -> Result<...> { ... }
+ pub async fn transfer<S: Signer<PlatformAddress> + ...>(
+     ...,
+     outputs: impl IntoIterator<Item = (PlatformAddress, Credits)>,
+     ...
+ ) -> Result<...> { ... }

Same shape for transfer_with_change_address.

Bonus simplification

The original "collect to IndexMap internally" step turned out to be dead weight — both functions immediately canonicalized to BTreeMap next. The IndexMap layer never carried load-bearing insertion-order semantics. Dropped: public boundary now collects directly into BTreeMap. Fewer allocations, identical observable behavior.

Callers unchanged

  • FFI's parse_outputs still returns IndexMap<PlatformAddress, Credits> (needed for the duplicate-rejection check from CMT-003). It passes straight through to transfer(...)IndexMap impls IntoIterator<Item = (K, V)>, so the call-site compiles untouched.
  • BTreeMap, Vec<(K, V)>, HashMap, arrays — all valid callers now. New unit test transfer_with_change_address_accepts_btreemap_outputs pins this so future refactors don't tighten the bound.

Internal helpers

Surveyed 6 internal helpers currently using IntoIterator bounds (saturating_sum_credits, checked_sum_credits, build_auto_select_candidates, detect_no_selectable_inputs, validate_change_address, build_transfer_persistence_entries). All are single-pass walks with no random access — concrete map would be strictly more restrictive without simplifying. Kept as IntoIterator.

Verification

  • Insertion-order audit: no code between collect() and the downstream BTreeMap canonicalization depends on the input's insertion order. The one next() read in transfer_with_change_address deliberately reads the lex-smallest entry (BTreeMap-canonical "output 0" under [ReduceOutput(0)] semantics) — was always BTreeMap-order, not insertion-order.
  • cargo fmt --all: clean
  • cargo clippy --workspace --all-targets -- -D warnings: clean
  • cargo test -p platform-wallet --lib: 147 / 147 (+1 new)
  • cargo test -p platform-wallet-ffi --lib: 83 / 83

🤖 Co-authored by Claudius the Magnificent AI Agent

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Code Review

The head commit ece54f9369d70d7b682c228b7349aa5b92e73405 does introduce one real in-scope regression in the Rust wallet API. The rest of the reviewed concerns are either unchanged pre-existing issues or in untouched codepaths, so they should be tracked separately rather than block this PR.

🔴 1 blocking

1 additional finding(s)

blocking: `IntoIterator` outputs reintroduce silent duplicate-destination collapse at the public API boundary

packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs (line 41)

Changing transfer() from IndexMap<PlatformAddress, Credits> to impl IntoIterator<Item = (PlatformAddress, Credits)> removes the old type-level uniqueness guarantee, and the immediate collect::<BTreeMap<_, _>>() silently keeps only the last row for any repeated address. That behavior is newly exposed by this PR: direct Rust callers can now pass Vec/slice data such as [(A, 10), (A, 20), (B, 5)], and the signed transition becomes {A: 20, B: 5} with no error. The same unchecked canonicalization was added to transfer_with_change_address() at lines 195-206, so duplicate user_outputs are also collapsed before change and fee-target validation runs. This changes the total requested outputs, can drop an intended recipient amount, and can move the effective ReduceOutput target after canonicalization. The FFI path still rejects duplicate outputs in parse_outputs(), so this is a real regression introduced by widening the Rust API surface in this commit.

🤖 Prompt for all review comments with AI agents
These findings are from an automated code review. Verify each finding against the current code and only fix it if needed.

- [BLOCKING] In `packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs`:41-47: `IntoIterator` outputs reintroduce silent duplicate-destination collapse at the public API boundary
  Changing `transfer()` from `IndexMap<PlatformAddress, Credits>` to `impl IntoIterator<Item = (PlatformAddress, Credits)>` removes the old type-level uniqueness guarantee, and the immediate `collect::<BTreeMap<_, _>>()` silently keeps only the last row for any repeated address. That behavior is newly exposed by this PR: direct Rust callers can now pass `Vec`/slice data such as `[(A, 10), (A, 20), (B, 5)]`, and the signed transition becomes `{A: 20, B: 5}` with no error. The same unchecked canonicalization was added to `transfer_with_change_address()` at lines 195-206, so duplicate `user_outputs` are also collapsed before change and fee-target validation runs. This changes the total requested outputs, can drop an intended recipient amount, and can move the effective `ReduceOutput` target after canonicalization. The FFI path still rejects duplicate outputs in `parse_outputs()`, so this is a real regression introduced by widening the Rust API surface in this commit.

Inline posting hit GitHub HTTP 422, so I posted the same verified findings as a top-level review body.

@lklimek lklimek removed the ready for final review Ready for the final review. If AI was involved in producing this PR, it has already had a reviewer. label May 26, 2026
…r APIs

ece54f9 flipped `transfer` / `transfer_with_change_address` to accept
`impl IntoIterator<Item = (PlatformAddress, Credits)>` and immediately
`.collect::<BTreeMap<_, _>>()` it. That collect is last-write-wins on
duplicate keys — a direct Rust caller passing
`Vec<(A, 10), (A, 20), (B, 5)>` silently produces `{A: 20, B: 5}`, with
no error, no warning, and the intended recipient amount dropped. Under
`[ReduceOutput(index)]` the canonical target can shift after
canonicalization, compounding the silent drop with a wrong fee target.

The FFI path is unaffected — `parse_outputs` already rejects duplicates
at the FFI boundary (CMT-003 in commit 2eab4f7). The regression exposed
direct Rust callers only.

Mirror the CMT-003 pattern at the Rust API boundary: walk the iterator
once, build the `BTreeMap` while checking `contains_key`, and return a
new typed `PlatformWalletError::DuplicateOutputAddress { address }` on
the first duplicate. Same allocation profile as the previous collect.

The new variant maps to `ErrorInvalidParameter (2)` at the FFI boundary
— it is a caller-supplied parameter bug, mirroring how `parse_outputs`'s
String-based duplicate rejection already routes via `From<String>`. No
new FFI code is introduced; no Swift mirror change is needed.

Pinned with two new unit tests:
- `transfer_rejects_duplicate_output_address`
- `transfer_with_change_address_rejects_duplicate_user_output_address`

The existing `transfer_with_change_address_accepts_btreemap_outputs`
still passes — `BTreeMap` callers with unique keys remain valid input.

Flagged by @thepastaclaw on PR #3554.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@Claudius-Maginificent
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Fixed in commit d991a91736 @thepastaclaw — the blocker on the IntoIterator boundary.

What changed

Mirror of the CMT-003 pattern at the Rust API boundary. New typed error variant:

PlatformWalletError::DuplicateOutputAddress { address: PlatformAddress }

Both transfer() and transfer_with_change_address() now run their iterator through a single helper before the BTreeMap collect:

fn collect_outputs_unique<I>(outputs: I) -> Result<BTreeMap<PlatformAddress, Credits>, PlatformWalletError>
where
    I: IntoIterator<Item = (PlatformAddress, Credits)>,
{
    let mut map = BTreeMap::new();
    for (addr, credits) in outputs {
        if map.contains_key(&addr) {
            return Err(PlatformWalletError::DuplicateOutputAddress { address: addr });
        }
        map.insert(addr, credits);
    }
    Ok(map)
}

A direct Rust caller passing Vec<(A, 10), (A, 20), (B, 5)> now gets Err(DuplicateOutputAddress { address: A }) instead of a silently-canonicalized {A: 20, B: 5}. Same allocation profile as the previous collect (single BTreeMap, no intermediate). ReduceOutput target indices can no longer shift after canonicalization because canonicalization can no longer drop rows.

FFI mapping

DuplicateOutputAddress routes to ErrorInvalidParameter (2) — symmetric with parse_outputs's String-based duplicate rejection (which lands on the same code via impl From<String> for PlatformWalletFFIResult). No new FFI code minted, no Swift/Kotlin mirror churn. Typed Display rendering survives the boundary as the message string, so callers can still distinguish duplicate-output from other invalid-parameter cases by message-match if needed.

Pins

  • transfer_rejects_duplicate_output_address
  • transfer_with_change_address_rejects_duplicate_user_output_address
  • duplicate_output_address_maps_to_invalid_parameter (FFI mapping)

Existing transfer_with_change_address_accepts_btreemap_outputs still passes — BTreeMap callers with unique keys remain valid.

Gates at HEAD d991a91736

  • cargo fmt --all — clean
  • cargo clippy --workspace --all-targets -- -D warnings — clean
  • cargo test -p platform-wallet --lib149 / 149 (+2)
  • cargo test -p platform-wallet-ffi --lib84 / 84 (+1)

0 unresolved inline review threads. Ready for re-review.

🤖 Co-authored by Claudius the Magnificent AI Agent

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Code Review

I verified the worktree at d991a91736bf9ff78d52bf35a4c39bc2946fb013 against the cited findings and the actual PR scope. The duplicate-output regression is fixed in the Rust transfer APIs, the new typed error is present, and the FFI layer now maps it to ErrorInvalidParameter; I found no new in-scope defects in this delta. I also re-checked the previously noted follow-ups and they still exist, but they remain outside this PR's stated goal of rejecting duplicate output addresses. Targeted cargo test commands could not be completed in this sandbox because the workspace build tries to download Tenderdash sources during dependency build.

Out-of-scope follow-up suggestions (3)

These are valid observations, but they are outside this PR's scope and should be handled in separate issues or author/maintainer-requested PRs rather than blocking this review.

  • Swift explicit-change fee targeting still uses Swift array position while Rust/DPP interpret ReduceOutput after canonicalization — This mismatch is still real on the current head. ManagedPlatformAddressWallet.swift still appends the change output and sets ReduceOutput(lastIndex), while the Rust wallet documents and enforces DPP's lexicographic BTreeMap ordering for outputs, so a lexicographically smaller change address can still become the actual fee-bearing output. It remains outside this PR because the delta only touches the Rust duplicate-output rejection path and FFI error mapping, not the Swift caller or the ABI contract for fee-target identity.
    • Follow-up: Create a separate issue or author/maintainer-requested PR to resolve explicit-change fee targeting by canonical Rust/DPP output identity rather than Swift insertion order.
  • Auto-selection still relies on a wallet snapshot that can diverge before broadcast — The documented TODO(QA-007) in auto_select_inputs() is still present: balances and fee headroom are selected from a read snapshot and then later used for signing and broadcast after state may have changed. That is a real robustness concern, but this PR explicitly targets duplicate output rejection and does not change the selection/broadcast lifecycle, so it should remain a separate tracked follow-up rather than an in-scope blocker here.
    • Follow-up: Create a separate issue or author-requested PR to re-validate balances and fee headroom immediately before signing/broadcast, or hold the relevant wallet state stable across selection and broadcast.
  • SPV runtime shutdown still depends on acquiring a write lock after run() holds a read lock across client.run().await — This liveness risk still exists on the current head: SpvRuntime::run() keeps the read guard alive while awaiting client.run(), and stop() still requires a write lock before it can call c.stop().await. The issue is unrelated to the transfer/output validation changes in this PR, so it should be tracked separately instead of being carried forward as an in-scope review finding for #3554.
    • Follow-up: Create a separate issue or author-requested PR to restructure SPV shutdown so the running client can be signaled without first waiting on the write lock.

… type signature

Revert transfer() and transfer_with_change_address() from
`impl IntoIterator<Item = (PlatformAddress, Credits)>` to
`BTreeMap<PlatformAddress, Credits>`.

Investigation of the DPP state-transition layer confirmed the
immediate BTreeMap canonicalization in these functions is
load-bearing: `AddressFundsTransferTransitionV0.outputs` is itself
a BTreeMap on the wire, and the chain's fee-deduction logic resolves
`ReduceOutput(index)` via `outputs.keys().collect::<Vec<_>>()` — see
rs-dpp/src/address_funds/fee_strategy/v0.rs:29-56. Caller-supplied
insertion order vanishes at serialization, so IntoIterator
misleadingly implied a contract the protocol does not honor.

Type-level effects:
- Duplicate output addresses are now structurally impossible at the
  API boundary; the explicit `DuplicateOutputAddress` variant and
  `collect_outputs_unique` helper added in d991a91 are removed
  as dead weight.
- FFI `parse_outputs` no longer needs IndexMap; returns BTreeMap
  with the same `contains_key`-based duplicate rejection.
- Rustdoc on both public APIs now documents the lex-canonical
  contract and the `ReduceOutput(i)` index space.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@Claudius-Maginificent
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Design pivot — outputs type signature flipped from impl IntoIterator to BTreeMap (commit b38e1237ee)

@thepastaclaw — this supersedes the DuplicateOutputAddress helper approach from d991a91736. Posting because that previous reply is now stale.

Why we pivoted

Investigation of the DPP layer confirmed the lex-order canonicalization inside transfer() is load-bearing, not vestigial:

  • AddressFundsTransferTransitionV0.outputs is a BTreeMap<PlatformAddress, Credits> on the wire.
  • Consensus fee deduction in rs-dpp/src/address_funds/fee_strategy/v0.rs#L29-L56 resolves ReduceOutput(index) by indexing into outputs.keys().collect::<Vec<_>>() of the BTreeMap. Index 0 is the lex-smallest address, not the first one supplied.
  • Caller-supplied insertion order vanishes at serialization.

impl IntoIterator accepted Vec<(addr, credits)> but no caller order ever reached the chain. The wallet was running a runtime helper (collect_outputs_unique) to reject duplicates and emit DuplicateOutputAddress — fixing a regression that the type system can prevent outright.

What changed in b38e1237ee

Item Before (d991a91736) After (b38e1237ee)
transfer() signature outputs: impl IntoIterator<Item = (PlatformAddress, Credits)> outputs: BTreeMap<PlatformAddress, Credits>
transfer_with_change_address() signature same shape user_outputs: BTreeMap<PlatformAddress, Credits>
Duplicate rejection Runtime check in collect_outputs_unique helper → Err(DuplicateOutputAddress) Structural — BTreeMap cannot contain duplicates by construction
PlatformWalletError::DuplicateOutputAddress Added Removed — unreachable
FFI parse_outputs return Result<IndexMap<…>, String> Result<BTreeMap<…>, String> — keeps the contains_key duplicate-rejection at the FFI boundary for Swift/Kotlin callers
indexmap crate dep Used Dropped from both rs-platform-wallet and rs-platform-wallet-ffi Cargo.toml
Rustdoc Both APIs now document the lex-canonical contract and ReduceOutput(i) index space

Net: 7 files changed, +50 / −209.

Tests

Crate Before After Δ
platform-wallet --lib 149 147 −2 (dup-rejection tests removed — type system enforces it)
platform-wallet-ffi --lib 84 83 −1 (dup-rejection FFI mapping test removed)

Side cleanup spotted in-passing: parse_outputs_preserves_insertion_order_for_distinct_addresses was misnamed and its fixture was accidentally in lex order, so it would have passed silently under a wrong implementation. Renamed to parse_outputs_yields_lex_order_for_distinct_addresses and the fixture flipped to non-lex order so the test now actually exercises the canonicalization.

Rustdoc excerpt

/// # Output order semantics
///
/// Outputs are stored on-chain in `AddressFundsTransferTransitionV0` as a
/// `BTreeMap<PlatformAddress, Credits>` — keyed by address, iterated in
/// lexicographic order. This is also the index space resolved by the
/// fee-strategy `ReduceOutput(i)`: index 0 is the lex-smallest output
/// address, not the first one supplied by the caller. The parameter type
/// `BTreeMap` is chosen to make this canonical ordering explicit at the
/// type signature.

Gates at HEAD b38e1237ee

  • cargo fmt --all — clean
  • cargo clippy --workspace --all-targets -- -D warnings — clean
  • cargo test -p platform-wallet --lib — 147 / 147
  • cargo test -p platform-wallet-ffi --lib — 83 / 83

0 unresolved inline review threads. Ready for re-review.

🤖 Co-authored by Claudius the Magnificent AI Agent

Comment thread packages/rs-platform-wallet-ffi/src/platform_address_types.rs Outdated
Comment thread packages/rs-platform-wallet-ffi/src/platform_address_types.rs Outdated
Comment thread packages/rs-platform-wallet-ffi/src/platform_address_types.rs Outdated
Comment thread packages/rs-platform-wallet/src/wallet/platform_addresses/transfer.rs Outdated
lklimek and others added 2 commits May 26, 2026 15:56
…surface

Three follow-ups on the auto-select-inputs PR:

- Revert the duplicate-address error type on parse_explicit_inputs,
  parse_explicit_inputs_with_nonces, and parse_outputs from
  Result<_, String> back to Result<_, &'static str>. The formatted
  hex breadcrumb in the diagnostic isn't worth widening the public
  surface; flat constant messages are sufficient.

- Add a tracing::warn! on the silent PlatformP2PKHAddress::from_address
  conversion drop in transfer.rs inside the filter_map building the
  owned-address lookup. Conversion failures are now visible in logs
  instead of being filtered out without a trace.

- Convert four debug_assert! invariants in transfer.rs to real runtime
  checks (or delete redundant pairs). debug_assert! is compiled out in
  release builds, so the Σ-inputs-equals-Σ-outputs guarantees at the
  end of select_inputs_deduct_from_input and select_inputs_reduce_output
  weren't actually defended in production. Two debug_asserts that were
  paired with following if-checks are removed as duplication.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…EnoughFunds

The output-centric variant name described the wallet's internal
address-graph state ("only output addresses are funded") rather than
the user-facing problem ("not enough funds to spend"). Renamed to an
input-centric narrative matching how callers reason about the error.

No semantic change: same fields, same FFI code (ErrorNoSelectableInputs
= 14 under the umbrella mapping), same Display payload survives the
boundary — only the variant name and the Display message wording change.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Code Review

Re-reviewed head 4965e425ae921723c391d8d7f1d45c99f09f9041 with focus on the delta since d991a91736bf9ff78d52bf35a4c39bc2946fb013: the IndexMapBTreeMap API/ordering pivot, transfer_with_change_address behavior, the OnlyOutputAddressesFundedNotEnoughFunds rename, and the tightened platform-address FFI error surface.

No new in-scope blocking findings from this pass. The latest changes are internally consistent with the canonical BTreeMap ordering decision, keep the FFI parse helpers on BTreeMap + &'static str, preserve ErrorNoSelectableInputs mapping for the renamed wallet error, and make the formerly silent P2PKH conversion skip visible via logging.

Checks run locally:

  • cargo check -p platform-wallet --lib
  • cargo check -p platform-wallet-ffi --lib
  • platform-wallet auto-select tests: 23 passed
  • platform-wallet-ffi platform address parsing tests: 4 passed

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