fix: terminal papi native signer

[decrypto21]

Closes #80 (PJS does not support this signed-extension: AsPgas in dot init).

Swaps getPolkadotSignerFromPjs for PAPI-native getPolkadotSigner in packages/terminal/src/signer.ts. Transaction signing now routes through session.signRaw({ data: { tag: "Payload", value: hex(toSign) } }) - an opaque-bytes wire route that already exists in @novasamatech/host-papp 0.7.7. polkadot-api assembles callData ‖ extras ‖ additionalSigneds for every signed extension declared by the runtime, and the wallet just signs the resulting bytes. Any extension carried by the chain - including ones polkadot-api's PJS adapter doesn't have a built-in mapper for (AsPgas on Paseo Next v2, future runtime extensions) - survives end-to-end.

Root cause

Two stacked limitations on the previous path:

1. @polkadot-api/pjs-signer hard-throws on any signed extension without a built-in mapper. The mapper table covers eight extensions only (CheckGenesis, CheckNonce, CheckTxVersion, CheckMortality, CheckSpecVersion, ChargeAssetTxPayment, ChargeTransactionPayment, CheckMetadataHash). AsPgas isn't in that list.
2. host-papp's SigningPayloadRequest codec has fixed slots (era, nonce, tip, assetId, metadataHash, mode, …) and signedExtensions: Vector(str) - names only, no payload bytes. Even if PJS were patched to pass AsPgas through, the wire format itself can't carry the extension's extra and additionalSigned bytes.

The Payload-tag route on session.signRaw is a tagged-bytes channel the upstream @novasamatech/product-sdk already uses for non-bytes-typed raw requests, so the wallet code path is exercised in the field.

Changes

• packages/terminal/src/signer.ts - replaces PJS-bridged construction with getPolkadotSigner(publicKey, "Sr25519", sign). signBytes is overridden post-construction to keep the Bytes-tag route (so the wallet's <Bytes>...</Bytes> anti-phishing wrap applies exactly once to arbitrary-data signing, not to tx signing).
• packages/terminal/README.md - updates the Signing section to document the new wire path and the AsPgas fix.

Two tiny helpers (makeTxSignCallback, makeRawBytesSignCallback) replace the previous PJS field-translation glue and are unit-tested directly. Net diff: +150 / −288 lines (refactor reduces the file because the PJS field-translation glue is gone).

What this does not fix (explicit scope)

This PR fixes the terminal/QR-paired flow only (createSessionSigner / createSessionSignerForAccount). The in-host signer path - packages/signer/src/providers/host.ts calling accountsProvider.getProductAccountSigner() from @novasamatech/product-sdk - stays PJS-bridged and will still throw PJS does not support this signed-extension: <name> for arbitrary extensions until two things happen upstream:

1. paritytech/triangle-js-sdks#168 merges - adds a signerType: 'createTransaction' option to getProductAccountSigner that builds a PAPI-native signer routing through the new host_create_transaction RPC.
2. We bump @novasamatech/product-sdk to the release containing that change and flip the option in packages/signer/src/providers/host.ts.

The upstream PR is currently OPEN, mergeable, awaiting review. The follow-up here is effectively one line per call site once it ships.

Consumer impact in the meantime: apps using createSessionSigner (CLI/QR-paired) are unblocked by this PR. Apps reaching mobile signing via the in-host host provider still hit the original error on AsPgas-bearing extrinsics. playground-cli uses createSessionSignerForAccount, so dot init is covered.

Validation

• pnpm check (biome lint + format, 205 files) - clean
• pnpm build (all packages + examples) - pass
• pnpm test - 725 tests across 14 packages, 0 failures
  • 13 in packages/terminal/src/signer.ts covering the new wire path and regression guards against the legacy signPayload call
• pnpm exec tsc --noEmit (terminal package) - clean
• Bundle size: no change (terminal stays at 4.6 KB gzip)

Test plan

• pnpm check (biome) — clean
• pnpm build (all packages + examples) - pass
• pnpm test — 725/725 across 14 packages
• Bundle size — no change (terminal: 4.6 KB gzip)
• Local e2e roundtrip against Paseo Next v2 Asset Hub

[github-actions]

📦 Bundle size impact

Comparing 2026-05-13T09:28:22.840Z → 2026-05-13T09:28:19.722Z

No size changes detected. 🟢

[UtkarshBhardwaj007]

LGTM