fix: 7702 authorization/legacy-tx signature encoding and Simple7702 revoke guard

[sherifahmed990]

Signature-encoding fixes on the EIP-7702 paths.

• Legacy transactions with leading-zero r/s were rejected by nodes: createAndSignLegacyRawTransaction encoded r and s from the 32-byte zero-padded hex, so any signature whose
  r or s has a leading zero byte (~0.8% of transactions, deterministic per key/payload under RFC 6979) produced rlp: non-canonical integer (leading zero bytes). Both are now encoded
  as minimal RLP integers via bigintToBytes, like the EIP-7702 path.
• High-s external signatures silently never applied delegation: EIP-7702 requires s <= n/2 in authorization tuples, and nodes silently skip high-s tuples during set-code processing — a signer callback returning a standard high-s signature failed with no error surfaced. parseRawSignature now normalizes to the complementary low-s form (s' = n − s,
  flipped parity), matching the private-key path.
• Simple7702 revoke could revoke the wrong account's delegation: createRevokeDelegationTransaction fetched delegation status and the nonce for accountAddress but signed with
  eoaPrivateKey unconditionally — with a mismatched key, the broadcast transaction revoked the signer's delegation instead. The same up-front key/address check the Calibur revoke
  path has is now applied.

Also moves the secp256k1 constants above parseRawSignature for read-before-use ordering (no behavior change).

Summary by CodeRabbit

• Bug Fixes

  • Prevented delegation revocation when the supplied private key does not match the account address.
  • Improved transaction signature encoding to use canonical, minimal formats.
  • Normalized high-s signatures for EIP-7702 authorizations, improving compatibility and validation.

• Tests

  • Added coverage for canonical signature encoding and low-s normalization.

[coderabbitai]

📝 Walkthrough

Walkthrough

The change canonicalizes legacy ECDSA signature encoding, normalizes EIP-7702 signatures to low-s values, adds coverage for both behaviors, and validates that revoke-delegation private keys match the account address.

Changes

Signature and delegation correctness

Layer / File(s)	Summary
Canonical legacy signature encoding src/utils7702.ts, test/utils7702.test.js	Legacy transaction signatures use minimal big-endian RLP integers, with tests verifying encoding and sender recovery.
EIP-7702 low-s normalization src/utils7702.ts, test/utils7702.test.js	Standard and compact signatures normalize high-s values and flip parity, with authorization tests covering the result.
Revoke-delegation signer validation src/account/simple/Simple7702Account.ts	Revoke-delegation creation rejects private keys whose derived address differs from the configured account address.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• candidelabs/abstractionkit#80: Introduced or expanded the revoke-delegation helper refined here.
• candidelabs/abstractionkit#86: Also changed parseRawSignature signature component handling.
• candidelabs/abstractionkit#215: Modifies the same delegation validation and signature canonicalization areas.

Suggested reviewers: sednaoui, andrewwahid

Poem

I’m a rabbit with signatures neat,
Low-s hops make the encoding complete.
Keys now match the account they defend,
High-s flips to its canonical friend.
RLP sheds each needless byte—
Hoppy correctness, sealed tight!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description covers the main changes, but it does not follow the required Summary/Test/Risk / Compatibility template.	Add the required ## Summary, ## Test, and ## Risk / Compatibility sections, and include test evidence plus any compatibility or rollout notes.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main changes: 7702 signature encoding fixes and the Simple7702 revoke guard.
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.

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[coderabbitai]

🧹 Nitpick comments (1)

src/utils7702.ts (1)

483-506: 🎯 Functional Correctness | 🔵 Trivial | ⚡ Quick win

Low-s normalization logic is correct; consider bounding r/s before trusting external signer output.

The flip (s = n - s, yParity = 1 - yParity) and the strict s > SECP256K1_HALF_N boundary correctly implement the EIP-2/EIP-7702 canonicalization rule. One gap: r and the pre-normalization s from an external signer callback are never checked against (0, n); a malformed compact/standard signature (e.g. s >= n) would still be "normalized" and returned as a well-formed-looking tuple instead of being rejected early, deferring the failure to silent on-chain tuple-skipping described in the docstring.

Optional validation

 	const r = BigInt(`0x${sig.slice(0, 64)}`);
+	if (r <= 0n || r >= SECP256K1_N) {
+		throw new RangeError(`invalid signature r value: out of range`);
+	}
 	let yParity: 0 | 1;
 	let s: bigint;

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/utils7702.ts` around lines 483 - 506, Validate the parsed r and
pre-normalization s values in the signature parsing flow before applying low-s
normalization: both must be greater than zero and less than SECP256K1_N,
otherwise reject the external signer output. Preserve the existing yParity
handling and complementary low-s flip for valid values, using the parsed r
symbol alongside s.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@src/utils7702.ts`:
- Around line 483-506: Validate the parsed r and pre-normalization s values in
the signature parsing flow before applying low-s normalization: both must be
greater than zero and less than SECP256K1_N, otherwise reject the external
signer output. Preserve the existing yParity handling and complementary low-s
flip for valid values, using the parsed r symbol alongside s.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: fcf52971-4b18-40ea-acfa-b66f57c6d555

📥 Commits

Reviewing files that changed from the base of the PR and between a4f98c7 and a2fd5ac.

📒 Files selected for processing (3)

• src/account/simple/Simple7702Account.ts
• src/utils7702.ts
• test/utils7702.test.js

[Sednaoui]

LGTM