fix(serviceoffercontroller): align well-known/x402 resource path with openapi for inference/agent

[bussyjd]

Problem

For hostname-bound inference and agent ServiceOffers (the common case: spec.type empty/inference/agent, no custom spec.routes), the two discovery surfaces advertised different paths for the same paid operation:

• openapi.json — built by buildOfferScopedOpenAPI → openAPIPathsForOffer, which special-cases inference/agent and always emits a single path /v1/chat/completions, ignoring spec.routes.
• /.well-known/x402 — built by buildOfferWellKnownX402, which iterates EffectiveRoutes() and maps each route path via openAPIRelPathForRoute. With no declared routes, EffectiveRoutes synthesizes a paid catch-all /*; openAPIRelPathForRoute("/*") collapses to "", so the resource URL became <origin>/ (offer root).

An x402 crawler that cross-references openapi.json with /.well-known/x402 therefore saw <origin>/v1/chat/completions vs <origin>/ and treated them as disagreeing resources. HTTP/fine-tuning offers with an explicit route table already agreed; the bug was only the inference/agent hardcoded-path special-case known to one builder.

Fix

In internal/serviceoffercontroller/offerbundle.go only:

1. Added openAPIRelPathForOfferRoute(offer, routePath), which mirrors openAPIPathsForOffer's per-type path selection: inference/agent → fixed /v1/chat/completions; every other type → existing openAPIRelPathForRoute(routePath).
2. buildOfferWellKnownX402 now builds each resource URL with that helper instead of calling openAPIRelPathForRoute directly.

openAPIPathsForOffer, openAPIRelPathForRoute, and buildOfferWellKnownX402FromOpenAPI are unchanged.

Regression pin: TestBuildOfferBundles_InferenceOfferAgreesWithOpenAPI in hostoffer_test.go — hostname-bound inference offer with no Spec.Routes; asserts openapi paths is exactly /v1/chat/completions and x402.json resources[0].resource is https://…/v1/chat/completions.

Diagram

flowchart LR
  subgraph offer [ServiceOffer inference/agent]
    Type["spec.type = inference|agent"]
    Routes["spec.routes empty → EffectiveRoutes synthesizes /*"]
  end

  subgraph builders [Discovery builders]
    OA["openapi.json builder\nopenAPIPathsForOffer"]
    XK["/.well-known/x402 builder\nbuildOfferWellKnownX402"]
  end

  subgraph pathLogic [Shared per-type path logic]
    Helper["openAPIRelPathForOfferRoute\n(or openAPIPathsForOffer equivalent)"]
    Fixed["/v1/chat/completions"]
  end

  Type --> OA
  Type --> XK
  Routes --> XK
  OA --> Helper
  XK --> Helper
  Helper --> Fixed
  Fixed --> OAOut["openapi paths:\n/v1/chat/completions"]
  Fixed --> XKOut["x402 resource:\norigin + /v1/chat/completions"]
  OAOut -.->|agree| XKOut

Loading

Validation

$ gofmt -l internal/serviceoffercontroller/offerbundle.go internal/serviceoffercontroller/hostoffer_test.go
# (no output)

$ go build ./...
# (exit 0)

$ go test ./internal/serviceoffercontroller/... -count=1
ok  	github.com/ObolNetwork/obol-stack/internal/serviceoffercontroller	3.005s

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https://claude.ai/code/session_01PnhCQLz7CHuDBUhWd5xF8v