fix(live-runner): per-signer payment type on the LR path (dual-path sibling to #46) (#47)

Sibling to #46. #46 gives the **BYOC** payment path a per-signer
dual-path; this gives the **Live Runner** payment path the same, so
selecting an LR runner doesn't break payment on the default (Daydream)
signer.

## The bug
`_get_runner_payment` (live_runner.py) hardcoded `type="live"` for every
non-scope runner. `signer.daydream.live` only accepts `lv2v` → **`400
invalid job type`** → LR payment fails. The `lr-gateway` `lv2v` patch
only fixed the isolated sidecar; the gateway itself was still broken for
LR + Daydream. Without this, the transparent-routing plan's **Scenario 1
(Daydream + LR) breaks**.

## The fix
- Canonical `_payment_type_for_signer` moved to **`remote_signer.py`**
(the module that owns `LivePaymentSession`) so **both** payment paths
share it and LR does **not** import the soon-deprecated `byoc.py`.
Legacy Daydream → `lv2v`; modern signers → `byoc`.
- `_get_runner_payment`: Scope/LV2V stays `lv2v`; every other runner
uses the per-signer switch.

Two files, +28/−2. Both compile.

## Verified
Generalizes the exact fix proven on-chain via the lr-gateway `lv2v`
patch: LR single-shot + Daydream signer → `Payment tickets processed,
totalTickets=1` on Arbitrum.

## Follow-up
Once #46 merges, `byoc.py`'s local `_payment_type_for_signer` copy
should import this canonical one (trivial dedup) — the two PRs touch
disjoint files so they merge without conflict.

## Test
- [ ] `py_compile` (passes locally)
- [ ] LR + Daydream signer → `type:lv2v` → ticket redeems (the
Scenario-1 gate)
- [ ] LR + modern signer → `type:byoc` (gated on the pymthouse upstream
fix + orch byoc-single-shot verification)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: seanhanca

src/livepeer_gateway/live_runner.py

@@ -21,6 +21,7 @@
     GetPaymentResponse,
     LivePaymentSession,
     _freeze_headers,
+    _payment_type_for_signer,
     get_signer_info,
 )
 
@@ -737,10 +738,19 @@ async def _get_runner_payment(
     signer_url: str,
     signer_headers: Optional[dict[str, str]],
 ) -> tuple[LivePaymentSession, GetPaymentResponse]:
+    # Scope/LV2V is a live-video job → always "lv2v". Every other runner (single-shot
+    # fal/tool caps) pays via the per-signer dual-path: legacy Daydream → "lv2v",
+    # modern signers → "byoc". The old hardcoded "live" was rejected by the Daydream
+    # signer ("invalid job type"), breaking LR payment on the default signer.
+    payment_type = (
+        "lv2v"
+        if runner is not None and runner.app == "live-video-to-video/scope"
+        else _payment_type_for_signer(signer_url)
+    )
     session = LivePaymentSession(
         signer_url=signer_url,
         signer_headers=signer_headers,
-        type="lv2v" if runner is not None and runner.app == "live-video-to-video/scope" else "live",
+        type=payment_type,
         payment_params=challenge.payment_params,
         manifest_id=challenge.manifest_id,
         orchestrator_url=challenge.orchestrator_url,

src/livepeer_gateway/remote_signer.py

@@ -8,8 +8,9 @@
 import ssl
 from dataclasses import dataclass
 from functools import lru_cache
-from typing import Any, Optional
+from typing import Any, Literal, Optional
 from urllib.error import HTTPError, URLError
+from urllib.parse import urlparse
 from urllib.request import Request, urlopen
 
 import aiohttp
@@ -19,6 +20,21 @@
 from .errors import LivepeerGatewayError, PaymentError, SignerRefreshRequired
 _LOG = logging.getLogger(__name__)
 
+_LEGACY_DAYDREAM_SIGNER_HOST = "signer.daydream.live"
+
+
+def _payment_type_for_signer(signer_url: str) -> Literal["byoc", "lv2v"]:
+    """Select the payment payload shape for the target signer.
+
+    Legacy Daydream signer (signer.daydream.live) accepts only type:"lv2v";
+    modern signers (pymthouse DMZ, …) accept type:"byoc". Shared by the BYOC and
+    Live Runner payment paths so both speak the dialect their signer understands.
+    """
+    hostname = (urlparse(signer_url).hostname or "").lower()
+    if hostname == _LEGACY_DAYDREAM_SIGNER_HOST:
+        return "lv2v"
+    return "byoc"
+
 @dataclass(frozen=True)
 class GetPaymentResponse:
     payment: str