feat: Enforce EVM-stringent validation on proposal action ABI inputs

[thekidnamedkd]

Description

In relation to #719 -- this hardens ProposalActionsDecoder form validation based on findings from the review of #719. The principle applied: validate the shape of ABI types exactly as strictly as the ABI spec defines them — no stricter, no looser (#719 fixed a too-strict case; this fixes the too-loose ones).

Why

The decoder's live encoding wraps encodeFunctionData in a silent try/catch (proposalActionsDecoder.tsx). When form validation passes but viem throws, the data field silently stays 0x — and a submitted action with data: 0x isn't a failed action, it's a different action (a bare call / ETH transfer to the target). In a governance context that output gets voted on, not double-checked. Three validation gaps could reach that state (all verified empirically against viem 2.52.2):

1. Signed int* types had no validation branch at all — only the required check. A lone - passed validation; viem throws Cannot convert - to a BigInt; the error was swallowed. (Also: BigInt('') === 0n, so only the required check stood between an empty int and silently encoding as zero.)
2. No bit-width range validation — uint8 with value 300 passed the ^[0-9]*$ regex; viem throws not in safe 8-bit unsigned integer range; swallowed.
3. Address checksums were not verified — addressUtils.isAddress defaulted to strict: false, so a mixed-case address with a wrong EIP-55 checksum validated. That discards the checksum's entire purpose: catching typos/corruption on the one field where a mistake is irrecoverable. All-lowercase addresses still pass (verified — viem's strict mode only enforces the checksum when the input is mixed-case).

Changes

• proposalActionsDecoderUtils: new validateSignedNumber (format) and validateNumberRange (BigInt bounds per bit-width, signed and unsigned, default 256); validateValue now covers int* and checks ranges after format; address validation uses { strict: true }.
• ProposalActionsDecoderTextFieldEdit: the numeric input sanitizer no longer allows a leading - for unsigned types (it previously did, and only the regex validator caught it afterwards).
• New copy messages signedNumber and numberRange under proposalActionsDecoder.validation (minor bump — additive copy API, same as previous copy additions e.g. feat(APP-823): Decoded action form input UX improvements #701).

With these in place, no value that passes validation can make encodeFunctionData throw, which closes the silent-0x channel from the input side. The try/catch remains as intended for transient keystroke states.

Not included (deliberately)

• Surfacing encode failures in the UI: with spec-exact validators the catch should now only see transient states; if we ever want a visible error there it needs a small design decision and its own PR.
• bytes fields still require an explicit 0x for empty bytes rather than accepting a blank field — that's the canonical representation (viem's Hex contract; JSON-RPC DATA requires the prefix) and blank-vs-empty ambiguity on calldata is worth keeping explicit.

How to test: Storybook → ProposalActions.Decoder → ArrayType story with mode: EDIT: paste a mixed-case address with one letter's case flipped → checksum error appears; all-lowercase or correctly-checksummed → accepted. Unit tests cover the int/range branches (uint8 255/256, int8 ±127/128/−129, uint256 boundary, lone -, unparsable values).

Type of change

• New feature (non-breaking change which adds functionality)

Developer Checklist:

• Manually smoke tested the functionality locally
• Confirmed there are no new warnings or errors in the browser console
• Made the corresponding changes to the documentation
• Added tests that prove my fix is effective or that my feature works
• Confirmed there are no new warnings on automated tests
• Selected the correct base branch
• Commented the code in hard-to-understand areas
• Followed the code style guidelines of this project
• Reviewed that the files changed in GitHub's UI reflect my intended changes
• Confirmed the pipeline checks are not failing

Review Checklist:

• Tested locally that all Acceptance Criteria or Expected Outcomes are satisfied
• Confirmed that changes follow the code style guidelines of this project

[Copilot]

Pull request overview

Hardens the ProposalActionsDecoder edit-mode form validation so ABI inputs are validated to EVM/ABI constraints (signed ints, bit-width bounds, and strict EIP-55 checksum checking) to prevent cases where invalid inputs silently fall back to data: 0x due to encodeFunctionData errors being swallowed.

Changes:

• Add signed int* validation and numeric bit-width range checks (signed/unsigned), and enable strict checksum validation for address.
• Update numeric input sanitization to disallow - for unsigned number types while preserving it for signed types.
• Add new validation copy strings and a changeset entry for the minor release.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/modules/components/proposal/proposalActions/proposalActionsDecoder/proposalActionsDecoderUtils.ts	Adds signed int validation, range checking, and strict address validation.
src/modules/components/proposal/proposalActions/proposalActionsDecoder/proposalActionsDecoderUtils.test.ts	Adds/extends unit tests for new numeric validation branches.
src/modules/components/proposal/proposalActions/proposalActionsDecoder/proposalActionsDecoderTextField/proposalActionsDecoderTextFieldEdit.tsx	Updates numeric sanitization to treat signed/unsigned differently for -.
src/modules/components/proposal/proposalActions/proposalActionsDecoder/proposalActionsDecoderTextField/proposalActionsDecoderTextFieldEdit.test.tsx	Updates component tests for the sanitizer behavior.
src/modules/assets/copy/modulesCopy.ts	Adds signedNumber and numberRange validation copy strings.
.changeset/evm-stringent-abi-validation.md	Declares a minor version bump and documents the validation hardening.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[milosh86]

Looks good 👍