fix: facade TaggedArg encoding, native byte arrays, remove broken Ed25519Signer.fromMnemonic

[scarmuega]

Plan

Tx3 Trellis domain plan plans/feedback-cba-04-sdks-imports-utxoref-signer-encoding.md (domain root not yet on a forge; plan ref by path). Executed by org/coder under plan dispatch.

Done criterion (web-sdk share):

• TS Hydra init aggregate args now encode into the TaggedArg wire form on the facade path (previously raw → (-32005) target type not supported: List / value is not bytes) — met, pinned by unit tests.
• Ed25519Signer.fromMnemonic resolved per the plan's decision rule — removed (see below), snippets/e2e already use CardanoSigner.

Draft because: CI's codegen-check type-checks the rendered .trix template against tx3-sdk@latest from npm; the template now calls the new withTxParams/paramsFromSchema API, so that check stays red until the release carrying this PR publishes (verified locally against the built SDK instead — see Verification). Everything else is green. Ordering: merge → release → codegen-check green → re-point codegen-v1beta0.

What changed

1. fix(tii) — the bytes encoder canonicalizes native byte arrays (Uint8Array, or integer arrays — the JSON shape other SDKs' native byte arrays serialize to) to 0x-prefixed hex, per SDK spec §3.9. Previously a Uint8Array fell through to the envelope passthrough and serialized as {"0":1,...}. Regression tests cover the Hydra init and Asteria name shapes.
2. fix(facade) — the type-directed encoder shipped in feat(tii): type-directed argument encoding to the TaggedArg wire form #36 ran only on the dynamic Invocation path; the facade TxBuilder.resolve() (used by Tx3Client and every codegen-generated binding) sent args raw. TxBuilder now carries a ParamMap; Tx3ClientBuilder threads per-tx params — automatic from a loaded Protocol (new Protocol.txParams), explicit for codegen via new withTxParams. fromParts unchanged: existing generated clients keep compiling and behave as before.
3. fix(signer)! — removed Ed25519Signer.fromMnemonic. Plan decision rule applied: this is not a fixable derivation bug. The constructor used mnemonicToSeedSync(phrase).slice(0, 32) as a raw ed25519 key — no CIP-1852 derivation — so its witness vkey can never hash to the payment credential of the caller-supplied Cardano address: the signature was internally valid but never satisfied the tx's required signer (the reported "witness that does not sign"). It cannot be fixed inside a raw-key signer: a CIP-1852 address binds to a BIP32-Ed25519 extended key whose scalar plain RFC 8032 signing cannot accept. The class stays — it is not redundant with CardanoSigner: spec §3.5 requires it as the generic raw-key signer, and fromHex/new serve genuine raw ed25519 keypairs. Mnemonic construction belongs to CardanoSigner.fromMnemonic, which derives m/1852'/1815'/0'/0/0 and verifies the key↔address binding at construction. New cardano.test.ts pins both witness properties (vkey↔address, signature↔vkey) plus mismatch rejection. README and e2e already used the correct constructors; no snippet changes needed. BREAKING CHANGE footer carried on the commit.
4. fix(codegen) — .trix/client-lib/protocol.ts.hbs embeds per-tx params schemas + components.schemas and wires them through withTxParams; standalone package.json floor bumped to ^0.15.0.

Verification

• npm run test:unit: 163 passed (150 baseline + 13 new), 10 suites.
• npm run type-check (tsc --noEmit) and npm run build (tsup): clean.
• Local codegen-check equivalent: tx3c codegen rendered the template against the transfer fixture; the module type-checks (tsc --noEmit --strict --exactOptionalPropertyTypes --module nodenext) in a fresh consumer project against this branch's built SDK.
• Pre-existing finding, not touched: npm run lint fails repo-wide (ESLint 9 installed, no flat eslint.config.js); lint is not in CI.

Escalations / follow-ups

• Release act (org/founder): publish the release carrying this PR, then re-point the codegen-v1beta0 tag so trix users get the new template.
• Parity: rust-sdk carries the reference change (fix: facade TaggedArg encoding, native byte arrays, codegen UtxoRef/Address imports rust-sdk#47); python/go received the mirrored bytes-encoder fix; their facade wiring and their (equally broken) Ed25519Signer mnemonic constructors are filed as a follow-up plan in the domain root.

🤖 Generated with Claude Code

[scarmuega]

Merging with codegen red, by decision — the failure is release ordering, not a defect.

The codegen job type-checks the rendered template against the published
tx3-sdk on npm. This PR raises the template floor to ^0.15.0 (the generated
client now passes per-tx params schemas through the facade), and npm's newest
tx3-sdk is 0.14.0 — so the check cannot pass before the release, and the
release cannot happen before this merges. Same root cause as
tx3-lang/rust-sdk#47.

Order: merge → publish 0.15.0 → codegen goes green on main → re-point the
codegen-v1beta0 tag. Per sdk-spec/release-policy.md ("All SDKs MUST share
the same MAJOR.MINOR release train") 0.15.0 is a coordinated fleet cut across
rust/web/python/go.

Note for the changelog: this carries a breaking removal —
Ed25519Signer.fromMnemonic (a raw-key signer cannot satisfy a CIP-1852
address), which is what makes the fleet cut a minor, not a patch.

Green on this head: unit, e2e.